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AD-753 417
L.IGHTWEIGHT GEARBOX DEVELOPMENT FORPROPELLER GEARBOX SYSTEMS APPLICATIONSPOTENTIAL COATINGOS FOR TITANIUM ALLOYGEARS
Richard A. Hirsch
General Motors Corporation
Prepared for:
Air Force Aero Propulsion Laboratory
December 1972
DISTRIBUTED BY:
National Technical Information ServiceU. S. DEPARTMENT OF COMMERCE5285 Port Royal Road, Springfield Va. 22151
AFAPL-TR-72-90
LIGHTWEIGHT GEARBOX DEVELOPMENT
FOR PROPELLER GEAUbOX SYSTEM APPLICATIONS
POTENTIAL COATINGS FOR
TITANIUM ALLOY GEARS
R. A. Hirsch
Detroit Diesel Allison Division
LO• General Motors Corporation
Indianapolis Operations
TECHNICAL REPORT AFAPL-TR-72-90
December 1972
Approved for public release; -r '-)distribution unlimited -
Re0r•cc d by
NATIONAL TECHNICALINFORMATION SERVICE -....
U S Dopato~t c'•n C _,,mn-,.* A 22151
Air Force Aero Propulsion LaboratoryAir Force Systems Command
Wright-Patterson Air Force Base, Ohio
NOTICE
When Government drawings, specifications, or other data are used
for any purpose other than in connection with a definitely related Govern-
ment procurement operation, the United States Government thereby incurs
no responsibility nor any obligation whatsoever; and the fact that the
government may have formulated, furnished, or in any way supplied the
said drawings, specifications, or other data, is not to be regarded by
implication or otherwise as in any manner licensing the holder or any
other person or corporation, or conveying any rights or permission to
manufacture, use, or sell any patented invention that may in any way berelated thereto.
Copies of this report should not be returned unless return is required
by security considerations, contractual obligations, or notice on a specific
document.
UNCLASSIFIED-ISpcuuit Classification
DOCUMENT CONTROL DATA - R & DISecurity classification of title, body of abstract and indexing annotetior" must be entered when the overall report is clarsllled)
SORIGINATING ACTIVITY (Corporate afuthor) 20. REPORT SECUR'TY CLASSIFICATION
DETROIT DIESEL ALLISON DIVISION OF UNCLASSIFIEDGENERAL MOTORS CORPORATION 2b. GRoup
INDIANAPOLIS, INDIANA 462063 REPORT TITLE
LIGHTWEIGHT GEARBOX DEVELOPMENT FOR PROPELLER GEARBOXAPPLICATIONS POTENTIAL COATINGS FOR TITANIUM ALLOY GEARS
4 OESCRIPTIVE NO rES (T7v e- of report and inclusive dates)
Final ReportS AU THORtSI (FIset neme. middle Initial, last name)
Richard A. Hirsch
6 REPORT DATE 78. TOTAL NO OF P AJES 7b. NO. or REFS
December 1972 . Oy 17 None. CONTRACT OR GRANT NO 90- ORIG!9*ATORQS REPORT NUIABERIS1
F33615-70-C- 1383b. PROJECT NO DDA EDR 7326
306636 9b. OTHER REPORT NOISI (Any other numbers Mlat may be asslined
this erport)
d.
Itn O'STRIOUTION STATEMAENT
11 SU*PLEMENTARY NOTFS 112 SPONSORING UIL! TA"Y ACT!VITY
D034086 _ *,$' 0it-,I.s•4..;. lAir Force Aero Propulsion LaboratoryJ Air Force Systems Command
13 ABSTRACT • Wright-Patterson Air Force Base, Ohio131 AA•ST•AC T
The objective of this program is to develop the capability of titanium gears to sustain 126 millionrepetitive stress cycles at a surface contact stress of 132, 000 psi (based on steel modulus of elas-ticity. The achievement of this goal will make titanium gears significantly attractive for the 1975time period.Optimum titanium material composition was selected to provide desirable strength properties undcompatibility to the selected surface coating !system. Plated surface coatings, bonding techniques,heat treat processes, and surface lubrication coatings were investigated to provide an optimum sys-tem which would withstand the scheduled test requirements. Iron-plated coatings which were diffu-sion bondect to the titanium core and then cartonitrided to provide surface hardness were selected asthe most promising system.Test specimens were fabricated and tested or, the Tribometer to evaluate the surface durability andresistance to scoring. Additional specimens were tested on :he threo-ball-and-cone rigs to evaluatepitting fatigue life under high Hertzian rolling contact loads.Three s(-ts of test gears were designed and manufactured utilizing the dev2loped system. Experi-mental evaluation of the test gears estanlished their 107 cycle surface contact fatigue strength(baIsed on steel modulus of elasticity) at: Phase 1 96.000 psi Phase II 120, 000 psi Phase III152, 000 pbi.Secondary goals of oil starvation, oil contamination, and full-scale endurance tests were not accom-plished in order that process development could be continued to improve the small scale gear strength.
DD , O 1473 ]T 6c, VNCLASSLFLLI)
UNCLASSIFIEDSecurity Classification
24 LINK A -INK S LIIC CKEY WODOs I - i
ROLE WT ROLE WT ROLE WT
Titanium gears
Coated titanium gears
Aircraft gearing
Iron-plated titanium gears
Lightweight gearing applications
Diffusion bonding
UNC LASSIFIEDSe'urIt' CIa-irgcalon
AFAPL-TR-72-90
LIGHTWEIGHT GEARBOX DEVELOPMENT
FOR PROPELLER GEARBOX SYSTEM APPLICATIONS
POTENTIAL COATINGS FOR
TITANIUM ALLOY GEARS
R. A. Hirsch
Detroit Diesel Allison Division
General Motor! Corporation
Indianapolis Operations
TECHNICAL REPORT AFAPL-TR-72-90
IDecember 1972
Approved for public release;distribution unlimited
Air Force Aero Propulsion Laboratory
Air Force Systems CommandWright-Patterson Air Force Base, Ohio
_z-
FOREWORD
This final technical report was prepared by Detroit Diesel Allison Division, (DDA), of General
Motors Corporation, Indianapolis. Indiana, under USAF Contract F33615-?G-C-1383. The
contract was initiated under Project No. 3066, Task No. 306612. The contract was adm..•r'i-
stered by the Air Force Aero Propulsion Laboratory, Air Force Systems Command, Wright-
Patterson Air Force Base, Ohio. Mr. M. P. Wannemacher, (AFAPL/TBP) was Project
Engineer for the Air Force.
Mr. R. A. Hirsch, Section Chief, Mechanical Technologies, was Program Manager at DDA
for the project. Acknowledgment is made to the many contributors within DDA, especially
J. A. Burger, J. F. Kildsig, L. W. McBride, Q. 0. Shockley, P. L. Colcord, F. K. Lea,
and M. R. Chaplin.
This report covers the development of coated titanium gears from February 2, 1970 to
September 1, 1972, and is assigned DDA supplementary report number EDR 7326.
This report was submitted by the author December 1972. Publicition of this report do not
constitute Air Force approval oi the reports findings or conclusions. It is publishd crnly for
the exchange and stimulation of ideas.
Ernest C. Simp/nDirector
Turbine Engine Divi.ion
Air Force Aero Propulsion Laboratory
II
ABSTRACT
The objective of this program was to develop the capability of titanium geax. to sustain 126
million repetitive stress cycles at a surface contact stress of 132, 000 psi (based on steel
modulus of elasticity). The achievement of this goal will make titanium gears significantly
atu'z!cive for the 1H75 time period.
Optimum t.tanium material composition was selected to provide dcsirable strength properdies
an() compatibility to the selected surface coating system. Plated surface coatings, bonding
techniques, heat treat processes, and surface lubrication coatings were investigated to pro-
vide an optimum system which wc•-d withstand the scheduled test requirements. Iron-plated
coatings which were diffusion bonded to the titanium core and then carl~onitrided to provide
surface hardness were selected as the most promising :'ystem.
Test specimens were fabricated and tested on the Tribometer to evaluate the surface durab'.lity
and resistance to -coring. Additional specimens were tested on the thrce-ball-ano-cone rigs
to evaluate pitting fatigue life under high Ilertzian rolling contact loads.
Three sets of test gears were designed and manufactured utilizing the developed system. Ex-
periment,-d evaluation of the test gears established their 107 cycle surface contact fatigue
strength (based on ,:teel modulus of elasticity) at:
* 0 Phase I 96, 000 psi
0 Phase H 120, 000 psi
0 Phase 111 152, 000 psi
Secondary goals of oil starvition, oil contamination, and full-scale endurance tests were not
accomplished in order th-.t process development could be continued to improve tYhe small-scale
gear strength.r
!
II
TABLE OF CONTENTS
Section Title Page
Introduction ................... ................................. 1
1 Technical Discussion ................ ............................ 3
Titanium Alloy Selection .............. ........................ 3
Hard Surface Coating ............ .......................... 7
Electroless Nick.A (GI Nichen,) C0mating ..... .............
Electrodeposited Iron-Nickel Coating ....... ............... 9
Electrodepositad Iron Coatings ........... .................. 9
Hard Surface Coat Bonding ............ ....................... 18
Heat Treatment .......... ............................. .... 23
Nitride Process ................ .......................... 23
Carburizing Process ............. ........................ 24
Carbonitriding Process ............................. .... 24
Treatment Process ....... ......................... .... 26
Surface Lubricant Coatings ............ ....................... 31
Dow-Cornir- !-3M43 (AFMiL-41) ........ .................. 33
Silver + Telluride Ag-N-bTe2. ......... .................... 34
Teflon + Molybdenum Disulfide (Teflon- loS2 ) ............... 34
III Gear Design ................ .................................. 35
Phase I Gear Design ........ ........................... ... 35
Phase 1I and Il Gear Design ............ ...................... 36
IV Gear 'Manufac!ure ...... .............................. 43
V Testirng!Analysis .......... ............................... .... 49
Triborneter Tests ............. ............................. 49
Electroless Nickel (Nichem) Ward Coating ................... 51
Carbonitrided Iron and Iron Nickel Hard Coating ............ .1
STriborneter Test Conclusions ........... ................... 52
Three- Ball- ,.nd-Cone Tests ............. ...................... 56
Test Pa-ameters ......... .......................... ... 56
Oil Starvation Testing ............ ....................... 60
Three-Ball-And-Cone Test Conclusions ....... .............. 60
R. R. ".Wore Test'.. ................................... i. 2
R. R. Moor'e Test Conclusions ........... .................. 65
Crushing Tests .............. ............................. 65
('ru.l!ing 7Tst :coýclusions ........ .................... 65
V , Preceding gage blank
w
Section Title-_ _. Page_ _
Ryder Gear ............................ 66
Test Parameters................................... 68rtst Gear Load Schedules ........ ..................... 68Test Gear Inspection ............. . . . . ... ........
Ryder Gear Test Data.................................. 69MlAllugIy Analysis ....... ........................ .... 69
Gear Test Su- ...mary ..................................... 79
VI Conclusions and Reczrmu:endations :33...................................................... 3
Appendix 1. Comp.ter Output of the TIDA Gear Design Program ...... .... 85Appendix Hi. Ryder Gear Test Inspection Data Sheets For i.Hrd Coated,
Small-Scaf.• Titanium Gears..........................
Appendix ILL Gear Manuiacture Process Routing .................. 105
|vi
LIST OF ILLUSTRATIONS
Figure Title Page
1 Comparison of minimum tensile ultimate strengths at various
temperatures .................................. 5
2 Comparison -.f rm'inimum 0. 2% yield strengths at various temperatures . 5
3 Comparison of 107 fatigue strength ............ ..................... 6
4 Fatigue -4 rength vs section thickness and hardenability . .......... 6
5 Iron-nickel alloy segregation in tooth flank ........ ................. 9
6 Small volume plating rank ............ ........................... 10
7 Large volume plating tat;k ............. ......................... 11
8 •ijxi.U-ry anode plating fixtur..: .............................. ... 12
9 Silicone '-ubucr plating mask ........ ......................... .... 13
10 Micarta mask with gear tooth form spaces ............................ 14
11 Mask with z 1justable slot sizes ............ ....................... 15
12 Gear plated in adjustable slo'ted mask (0. 01-in. plate thickness) ..... 15
13 Fifth plate mask ...... ....... .............................. ... 16
14 Gear plated in fifth mask (0. 015-in, plate thickness) ...... ............ 16
15 Optimum plating mask .......... ........................... .... 17
16 Final optimum plated gear (0. 018-in. min plate thickness) .............. 17
17 Shielded plating anode .............. ............................. 18
16 Plated titanium diffusion test specimens ....................... . . 19
19 Vacuum diffusion zone ....... .............................. .... 21
20 Electroi, -nicroprobe study of iron coating and titanium . ......... 22
21 Electron micruy-obe study of iron-nickel coat;Ing and titanium ....... ..... 22
22 Iron coating structurt. with Tufftride heat treatment ...... ............ 24
23 Typical carbonitride of iron ,.,• titanium ...... .................. .... 26
24 Heat treatment hardness gradient ............ ...................... 27
25 Bending stress geometry ............. ........................... 36
26 Phase I wide gear design ............. ........................... 36
27 Phase I narrow gear design ....... ......................... .... 37
28 Subsurface stress distribution . . ...................... 38
29 Phast, 11 narrow gear design ....... .................... ...... ... 39
30 Phase II wide gear design .............. .......................... .39
31 A;arvufacture of gear tooth profile ............ ...................... 43
32 'ypical gear inspection charts ............. ........................ 46
33 Phase I finished gear set ........ ........................... ... 47
34 Phase III finished gear set ....... .......................... .... 47
35 Tribometer test rig and test parameters ......... .................. 49
36 Tribometer rotating specimen ............. ........................ 50
vii
Figure Title Page
37 Tribometer stationary platen specimen ........ ................... 50
38 Typical Tribometer test cylinder and platen ......... ................ 51
39 Typical failure Fe and Fe-Ni coating with electroless Ni bond medium . 52
40 Results of Tribometer testing of bare finish ground electroless Ni . . .. 53
41 Results of Tribometer testing of carbonitrided Fe + AFML (DC1-3943) . 5442 Summary of Tribometer friction testing ........ .................... 55
43 Three-ball-and-cone test rigs ...... ......................... .... 56
44 Three-ball-and-cone fatigue tester schematic ...... ................. 56
45 Three-ball-and-cone rig test specimens .. .... ................ .... 57
46 Three-ball-and-cone teat specimens ......... ...................... 58
47 Three-ball-and-cone test summary ...... ..................... .... 58
48 Typical cone specimen failure ...... ......................... .... 58
49 Typical microsection of pitting fatigue failure .................. .... 62
50 R. R. Moore test specimen ............ ......................... 63
51 R. R. Moore fatigue test summary ...... ..................... .... 63
62 R. R. Moore test specimens ............ ........................ 64
53 Phi,, :e I type gear: 36 teeth, hard coated with Fe-Ni alloy .............. 66
54 Phase 1i.11 typc gear: 21 teeth, hard coated with Fe ...... .......... 67
55 Ryder-ERDCO gea.' testei -.-:th antifriction gear head and CRC oil cart 68
56 Wide gear tooth fracture ........... ........................... 71
57 Fractured gear teeth induced by fatigue failh,re ............... 71
58 Phase II. 1 contact pattern of mislocated geac... ................. ... 72
59 Phase I. 2 gear tooth damage ................................... .. 73
60 Tooth plate thickness macro section..., . ..................... ..... 73
61 Photomicrograph of diffusion zone cracking. ,................. 74
62 Phase II. 3 gear teeth damage ....... ........................ .... 75
63 View of gear tab lock failure ......... ............................ 75
64 Phase III. 1 and . 2 gear damage by loose retaining nut ............. .... 76
65 Phase III. 3 test gear damage . ................... ........ .. 76
66 Phase III plating line defect ..................................... 77
67 Gear web failure .... .. ....................... 77
68 Case condition adjacent +o failure ........................... 78
69 Phase III. 5 test gear failure .................................... 78
70 Photomicrugraphs typical of the case strLuture. ...... ............... 79
71 S/N test schedule. ............. .. ............................. 80
viii
LIST OF TABLES
Table Title Page
I Composition of titanium alloys .............. ........................ 4
H Diffusion depth, inches, of iron and iron-nickel in Ti 6AI-2Sn-4Zr-6Mo . . 20
IL! Tensile properties after vacuum diffusion ......... .................. 21
!V Carbonitride surface hardness-depth ........... .................... 25
or Effects of low temperature treatment on surface hardness 15N- ...... 27
VI i•15N hardness values of specimens given final high-temperature temper
treatment of 450.F ............. ............................ .... 28
V_!! R 15- hardness values o~f specimens given final high-temperature temper
treatment of 550*F ............... ............................ 29
VIII R 15 , hardness values of specimens given final high-temperature temper
treatment of 650, 750, ant: 500*F.. ............................. 30
DX R 15N hardness values of specimens given final high-tomperature temper
treatment of 500°F ............... ........................... 31
X Tensile properties after simulated 600OF carbonitride and 350 to 950 0 F
temper ................. ................................... 32
Xi Tenitile properties after simulated 1550°F carbonitride and 350 to 950*F
temper ................ .................................... 33
XII Titanium material properties with 2. 0-2. 25 hr carbonitride cycle ..... 34SXIII Phase I test scheduik -surface stress ........... .................... 37
XIV Phase I test schedule--bending stress ..... ...................... .... 38
XV Phase II and III test schedule--surface stress ..... ............... .... 40
XVI Phase II and Ill test schedule--bending stress ..... ................ .... 41
XVII Phase I, II, and JI- narrow gear process dimensions (in.) ...... .......... 44
XVIII Phase I, II, and III wide gear process dimensions (in.) ..... ............. 45
XLX Summary of Tribometer wear scars ......... ........................ 55
XX Three-ball-and-cone test results iron-nickel alloy .................. ... 59
XXI Three-ball-and-cone test results iron-nickel alloy and iron ..... ......... 60
XXII Three-ball-and-cone test results--electroless nickel ...... ............ 61
XXIII Thermal prcecssing of R. R. Moore plated fatj test specimens ....... 63
XXIV R. R. Moore fatigue test results ......... ... ...... ................. 64
XXV Load schedules for small-scale titanium gears tested in Phase I, I1, and
XXVI Summary of Ryder gear tests conducted on -mnll-scale gears during
Phase I, II, and IIJ .............. ............................. 70
ix (Page x blank)
SYMBOLS
Sc - Calculated hertzian stress, psi
i , p - Poisson's ratio
E - Young's modulus of elasticity, psi
Wt - Tangential load, lb
#t - ?. essure angle at the operating pitch diar'e-ter
Fe - Effective face width, in.
R - Gear pitch radius, in.
R p - Pinion pitch radius, in.
TQ - Torque, lb in.
Sb - Calculated bending stress, psi
Dv - Stress parabola vertex
Fmin - Minimum face width
XHPSTC - X factor calculated from high point of single tooth contact
xi
SECIMON
Future technolocj" has establizher the need to consider the weight savings tha could be achieved
if high strength-to-weigh ra!'i materials could be used in aircraft gear applicatious.. The
a eight advantage and versatility of titanium eStablishes ift as a desirable gear malterial if its
contact su-faces could be conditianed tL withstand the high aint loadmg required for gear teeth.
Prior Military funded projects since 1954 have advanced the potetial of satisfactory opertitOn
of titanium gears up to the operating level of approxfiately 112. 000-psi hertzian contact stress.
Present. hardened steel gears have z comparable stress capability between 180,000 to 242,000
psi at 107 cycles.
Detroit Diesel Allison (DD.A) has completed a 30-month developmerit program La which iron
coated gears were developed and tested on a Ryder gear test rig.. The program was divided
into thret pLa4es with the ccncluning test gears achieving a stress level of !.2, 000-psi hertzia2n
contact stress.
The success of this program presents a technological advancement toward the ultimate goal of
- replacing steel gears with reduced weight components.
:1?
SECTJMr- 1
TEHUND-CAL DRSCL-SSM
TflANIUM ALLOY SEELFýBQN
Pabis!hed iniformatioa related to thte ase oz Uknlzý alliys; as a gea--r -erdrere-aed the iL--
portance 2atd sece~ssity for a soft.-,e 'ce btni~at off a high strength bAs lm. and the oz
systemn. TUt seleu-ton of the til-r-i- ailor had to be eapKiDe --d dewe!o~pen base mtl~-nt
properties ani at the s2=e time the bat tre-Az s reqau-d foe- "bese pr-ope•r•es =asc be
,ompauible with the processing 7aramesers for appling the co•ing system.
T1he design crLeria used for selecting m tiEta-ium gear allay x.-as s'm-iar to the seleetica. process
used for cartmrtzed and/or nit-rided steel gears: since tine r,&uremýe=s for the tiluei ma-
teral sheuld be very similar to th•a of the steel gear =••aer-iL Botii reqamre a hith yield
s -. w-a. good fai--gue i•c to resist cxcessihe ti.
It w-as rreferable that- the tizanium gear cor,ý materia! exhibit a imrde-ss off RC34 minimum to
reduce the hardness gradieu between coatmng a•. core and to prese= 2 core rel-ioaýhip, sut -
lar to that of steel gears.
T.he r.itanium material u-as required to have good hzrdenaiihtV- and prov-ide adequate Sreng.-
for coating support. regardless of section size.
The proposed surfzce hardening procedure and op.ur.urn core propervi de-elopment tempera-
ture should be compatible.
The ability of the alloy to accept the coating was believed to be of paraum-ount importance; how-
ever, m the selection of a titanium allov there appeared to be no great Jifference in coatability
of the materials considered. Other properties that cou!d influence material selection are
density, modulus of elasticity, Poisson's ratio, and thermal conductivity.
After considering the basic requirements for a titanijm gear material, it Lecomes apparent
that the alloys closest to meeting these requirements are the high strength alpha-beta titanium
alloys such as:
* Ti 6A1-4V (AMS-4928) 0 Ti 6A1-2Sn-4Zr-6Mo
* Ti 6A1-6V-2.Sn (AMS-4971) * Ti 6AI-5Zr-4Mo-lCu-0.2.Si (IMI Ti 700)(EMS-59030)
Composition of these allw.vs is shown in Table I.
3
Ta•ina L
______= Ti C-2-4-64" TR 6-44 TS S!-2 m '*4,
Var- 3.50-4.5-0 5. 0-6.C cc
0 ~e . ... 0._ax-0.O'" -. -i_,° 0
G-rro ~ 04ira 0- .0 Omax 10.05 =rax 0.. 15 max,
o.vge~ i0 no-- 0. 2"0 =2M 0.. 20 mTr: -
ir ogen 0.. 002 Max 0- 05 ='ZZ 0. 04 En --
pwda-ogean O.0.05z-a 0- 0! 25 n-3 0- G!5m 0..OIN3z
Other ele•-•ens --- O. --0 --ax 0. 40 m-- - - -
TfRi=femainder Ht-ma,-er Re- er -Icmder
tTi 6Al-Z2 S-4AZr-6l7o
tTi 6AI-SZr-4Mo- lCu-0- 251
•, ~(l..1 700) (E•,1•-5.•030)
1These materials exhibited ultimate strernths of i40, 000 .o 160, 000 psi in the solution :reated
and 190, 000 to 200, 000 in the -Aged condision.
The coatability of the listed alloys is essentilly the sa,. howeier, the compatibility of the
base metal heat treatment and coatin, heat treatment can vary- and is of great imp<, lance. If
the ahoy" is to be used in the solutioen hcat treated and aged (ondition, then the greatest flexibilitv
and strength response can be achieved with the alloys that a -e capable of being ai;--cooled from
the solution treating temperature. This would allow a marriage of the solution heat treatment
and coating thermal treatment.-i without the need for an integral rapid qr:ench facility, It also
minimized distortion and residual stresses caused by rapid quenching. With such a material a
selected coating treatment in the range of 1550 to 1650'F would also serve as the solution treat-
ment of the titanium alloy: any treatment below I l00', i.,e., ritriding. could be done within the
aging treatment or after the aginz treatment.
4
A ca=Prism 'o te~sik pspe!¶iiks as s&DUM Fie~rws I = 2 ufci shw tr;ý th& c.- - led
z alloys fail saso 2: respect~abe stre~g~ raege The aan-co d Ta 2---d42b-63ýr_ _coaled lIM! 7-TOO0 devetfla aDtine3L-ehs of 175. ~O PSIL or abon X.-
tm the falz~e=& properrt is sb" = Figmm- 3 =idzc-- tham e s lc- iztr dnfft-.e=, i*
the fative smerl of the wxEf_ q~r_--tbd Zd Oxr-CM'kd Tt aa~~4Z-h d fLUI Tz 7W_
As sbs4 lot of thes 2alr ?cate h~.I iO3er 1=!Voe SttCP: ftR. Tr. 9A-4Vi
* ~Ti ~-~~
qEsa UBC
Figuire 1. Comparison of minimm tensiie ultima e *rengths at rarious tempe-ratures..
4 a4-
All 3llavE are in the solution tzIIT
treated'and aged condition- 11.
M36- 3
Figure 2. Comparison of niinimum 0. V, yield strengths at various temperatures.
FuCcm 4 gbv" t;- -- le-i2i I SCMCOM2s reialie to Sectim tbkýs Z~~x&DdT
2=6 W. Ti Ts are the bký; the Water-*=Xr.ýt1d =atra WO~ re h B=
also ~±~i~ ~ ~z~a~re_ The Basmer swn'f~r ~ztS
Ls f=U- Cqf v'w marlutil ac-Bmcd br&- wtm~ 2--d~r M !f-set
Tý*~~ OtE
,- - +
31D --
CI M
fture~~7 3. -Z--&4of10
fatigue stmrgtb.
1 2
~1E~ ~&I~s-i~7326-5
Figure 4. Fatigue strength vs sectionthickness and hardenability.
~Tue~Eir seirn-=r tb as2 c~waxw at~ti aa=--cmbiei Tt Ir - _ Areter
semmvr4 BiDU Tz -a5 Th* air-c=Oe Tz VJ-25m-4Zr--S3&* -x3= Seý- &w tfs Ctar grom
T' Dba--tj zmsdrr cima±ng pirtw r¶-6ts, L e- . m-rcintme cace &=- ems am
Fe-91
A-I-.Wm __*fm -rswmntwst rt=e etr tPrerun 2#s ofr zhad nor :0~e 6v srrazl aopphd 2C W&u~ o St in * (1 ==& Ls=~ fO inese
Bczd*==; tmic~ess of1-1 MEDs t:-aS pCifie =oS Mxc fm-es. i core oamm~vh =;-ccn tn
0 ~ ~ ~ ~ F -lcrjs ncke (GZNch5n
*~~~~~~~~k Elcrdeoie Brn~mkl(a''nd
S Elcctroiepcs~ted iro Stac..
tt-ýIU Mmre ft -pca fe IA. 4p*m l'
:~terne Outimt -g s5 Mir za k tav stmixal 2**
-- DC mar- j as!c3 5c-!
Loc* Si* , 2zCIiTz- at 2- l !I-~rtg c-to~audw~
= = :"0eS~t tim-neg ev- f~u_- =2:is.. Th5±rA-_ etoa gS C= R:) fa& 4rvoyr :c1.0
* ~ ~ ~ ~ i p r~erove-2~tr.-e:5~'- -a~ :i'tes e.0c- fk_- CrM~-c -. e -t=
~~C all-. ic-oce~sst-e tetst gear :Ocr& Lse d'e-ie5- -n~ -~%s -nf Sion
,o--gor &6ring subseqz-m final opnan ez-al Cc-.
I h~e it.se of z1ass be.Ad pe~eninz Tras Irnplt-entede 10 Induce c es~esarfac42 sqt!s5ss and
:~,r.reduic- e cracking vendenc-. 01 `.e Ncheni plate- 'Glass pe-ening -A~s 5=d i-
sequ',ýv -o tne eievated temperature diffusion cycle (00GOý P- aszuLseouve.t to e-ad-. pi
opera-:on.. Alihou&h glass bead peening mezsurablh reduced the cracking ze=oency, tne condi-
.Ion Lojl-- -A *-e elimarnate-, ;ýecause of thi~s ckr-ditzon. fi~rthzer heý! v-. Xihr':kr p.-Ite de-.elop-
mrent on F-ea7-sWas SUSpe-Ided. FIrtiiermore. in the minital efforts to I-ond iron ad- iron-r.ieke1
e~ectrod~eposits to *hc titaniumn A~lu% test specimens. an elec-roless nickei: ýoalzinr 0. 1 to 0- 2
m.i `-uc' was used. T-he thi-I Nichemn .xa~ings, processetd and vacuum he~at treatedl (as pre'-
-iu.docscrmil. r.*) were lighill fine gril wet blasted and elect rochem icalli activated prior to
imncmrsion ir, tht. ironl and ir(,n-nickel platinz solution,5. TI- s-.stern worked well until the
; -"Fr --- p'r rluure htat treatrfl~cnlis 4,rl rcpid quern hts wecre use-d. NI, thlis time it was !earned
th.-r in# jiffL~sd' \;cerr would not withsliind the iherrmal shorks.
% ... ir=e ofarz tkes=2 o(dt zaqinrw diý !mwt~Ea offcr-w 6 cOS
Ttvx 2=*f= -ce Utvsr __m- Cm -C4 O phte! moz a -- twtz *# eaif t!
fot-_~=~ tw-d am t~~v& gearP~l sw-Em ~wit acý a~ sfi.= tie r_ 5et-r oas e
LE '-~ss ac-o n ta s -== Bt=-, bn~- adm_-t_. C=--% --- 6tm=-s- co:tý ~ I
=LS Of
F~gtre 6. SqmaL Tehme platimg WAr
Reszli!ns of -Ork eDiec ~~ e~-71=4 -,7-ra-o.s gea.r Comfigurairwc-s, ledi to sh cor---lusion-
thtat accem.able unifor= :hick6~~i of iron -. Or lroNM- nickel dt-.osa: Were notr n-aal~e o-.
gear'~~~~~~etb,-- bro I! sOff this e-asion, tnr-e'ý- ifr
technia. ,es for p-Tirý. ipezx wer ere o-ec :s folHOWS:
"* * -se a large sarnk -amere ithe ~na-xe " '--, lc;,-teý z: coddriie d rx.nc-Z ffron the sur-
faccs to0 be plate'd.
"* Use Various n-askirng hxt..,,rt s designezc -!o aid in equ;Alizing the plating distrii~ution over the
gear surfaces.
* 0 Use insolubie- auxilaxa-. anodes located near tne gear root surfaces.
Since plating accc-niplisned instl volu...e plating tank- ha.d de onstratced ansatisfactory,
*throwing power" to plate it-to recessed surface ar~eas of the ge~ar teetih, it was decided to tr-.
a large v-olume tarAk- where the nrode to cathode distance w.ould ierelu:1v.-i: ILrgc in co-mpari-
son to that obtained irn the small volume baths.
The enlarged plating ssic,-, *-o%%:- in iiu orsi of .. 200 :al 1i i:.pr'ryhne lin~ed tank-
with an acid re~i:F*ar~t pumnp anc filter -,nit, Four ih rmos,-ticz.ll\ controikdr electric quartz
irnnt-rsion hea: rs rn;flt~in soij~or *( :rpo rturf ---, thic u.,i, ib cqaipp( V. Iith .,n oscillhding
rod cathode agitatzor zinu ;:impl(, r -ul.t.or-2,O~
rim u.•.-___• T26-9
Fg-ure 7. Large vokmae pbtung taL
T-.e su.face o4• :he sant3m•n is covered '-itffi polyprog_-lere blJJs to reduce evaporati mn and'•r. losses.
The t,•ak was _•.•e,1•i GNIR L-on. Plating Solutio-r. (U. S. P--e.nt 3, 40(4-, 074) which is nominall~y
a-S folJoirs:
Ferrous chloride 465 gmin!
Ferrous iron 205 gm/ I
Dispers--t additive I gm/1
pl1 0.5
Temperature 190OF
Anodes Armro iror,
It wa• believed that the greater anode to cathode distan.ces obtainable in the large tank system
wJ-.ild equalize the plate thickness over the gear surfaces. While there was some small im -
pro% cment as compared to the small tank plated gears, the plating distribution was considered
to be unsatisfactory. A PR (periodic current reversal) control unit was added to the plating
current s. sem and periodic reversal current procedures were tried without any appreciable
improvement in -,ating distribution being noted. It wis hoped that PIN processing would reduce
the excess Ilate from the pitch hne outward while at the same time permitting greater deposi-
lion in the zear root area
II
Auxiliary anode plating feasibilit,' was tested by fabricating a fixture, Figure 8 which provided
the auriliary anoding on a gear segment. Insoluble auxiliary anodes were fabricated from
platinum pins placed parallel to thte root surfaces 1/8 in. from the root surfaces. Addition of
the auxiliary anodes appeare', "o provide additio:nal plate to £he root surfaces and was deemed
sufficiently promising to warra:nt addil ional testing,
By varing the anode to roo- distances, plate depths of 0. 008 to 0. 021 in. were obtained.
Although auxiia,- insoluble anodes were found to be helpful in depositing iron in the gear root
areas, use of the fixture was found to be 'oo difficult to cor.trol. As the plate depth built up,
oae or more of the anodes would short out due to misalignment or more rapid deposition in the
i, medte area causing the whole auxiliary anode unit to malfunction and cease plating in the
r(,,Pt .4rea. For these reasons the use of auxiliary anodes for this application was deemed un-
usable.
At this stag-c cf ;:i iLng development, the difficulty preventing attainment of a satisfact )ry
plated gear w.:.' lack of sufficient plating thickness in uhe root area of the gear. Up ,o this
time all plated gears nad .hown excessive build-up from the pitch line outward whvch resulted
in large nodules at tlie OD o: the gear teeth. While this was occurring tihe gear oot surfaces
were still deficient in pla,!ting tlhckness. Extended plating time, up to 32 hr, i. as of little help,
since the nodules grew larger with little improvement tn root plate thicknes,. It was concluded
tnat the formulation of the large nodules was the principle "eason for the' d, ficio., pl.,, ng thick-
ness being obtained in the root a'ea due to the fact that the nodules were st,, ing to shield and
rob the rest of the gear during the plating cycle. To remedy this situat ion, it was decided to
use the "through-the-window" plating principle.
7326-9
Figure 8. Auxiliary anode f 1iti,•g fxture.
12
Several through-the-window plating masks and fixtures were built and tested. The first one
was fabricated from filled -silicone rubber and was made to fit arid plate a 36 tooth gear. This
mask, Figure 9 was fabricated so that the effective window location, was (entered over the gear
tooth space with 0. 125 in. clearance above th. root surfaces. Plating accompiished with this
mask was more uniform in plate thickness than was obtainable by prior methoas. The plate
depth at the tooth pitch line of 0. 022 in. resulted in a plate depth of 0. 0: in. at the root in a
24 hr plating period.
The second mask was fabricated from Micarta to fit a 21 tooth gear. This mask was designed
similar to the rubber mask except the effective window opening was located with 0. 188 in.
clearance above the root surfaces.
Gears plated with this mask were unsatifactory because most of the plating occurred on the
upper half of the teeth while very little plkte was deposited on the root surfaces. Results of
the test indicated the effective window opening was too far away from the root surface.
The third mask, Figure 10, was fabricated from M'carta with 21 gear tooth form spaces whichprovide 0. 070 in. clearance with the gear teeth. The window openings were again located just
opposite the root fillet area. Plating with this mask was unsuccessful because the clearances
were too close, allowing plating buildup to contact the masi and made it difficult to remove
the gear from the mask.
7326-10Figure 9. Silicone rubber plating mask.
13
-- '
7326-11
Figure 10. Micarta mask with gear tooth form spaces.
The fourth mask was fabricated from Micarta to fit a 21 tooth ge.tr. The mask differed from
the previous ones in that the effective window openings are i~cated beyond the .)D of the gear.
The window slots of this mask were much longer than those of the previous masks. Several
plating runs were made with Lnis mask with the slot openings ranging from full open to very
small openings. The mask side opening vents were also varied in size to determine proper
size necessary to produce the desired web plate thickness. Figure 11 shows this mask and
Figure 12 the optimum gear plated with restricted slot openings with 0. 010-in. plate thickness.
The fifth Micarta mask was fabricated using the design configurations found to be most success-
ful when using the adjustable slot mask.
Figure 13 shows the mask and Figure 14 the optimum gear plated with 0. 015 in. min plate
thickness.
The sixth and final mask which incorporates the optimum features of the earlier development
masks is shown in Figure 15 and the optimum plated rx ask. The final optimum gear with 0. 018
in. min plate thickness is shown in I gure 16.
Platlin procedu, - and parameters were as follows:
1. De, rease
14
r
Sq F
7326-12
Figure 11. Mask with adji.Aable slot sizes.
%. I.
7326-13
Figure 12. Gear plated in adjustable slotted mask (0. 01-in,. plate thickness).
15
7326-14Figure 13. Fifth plate mask.
7326-15
Figure 14. Gear plated in fifth mask (0.015-in. plate thickness).
7326-16
Figure 15. Optimum pLAinig nia A
M36-17
Fig-ure 16. Final optimum plated gear.(0. 018-in. min plate thickness)
X CZV Wrt -- =ds ktt7 =It- Add~ 'ItR 94t~ 7L~r± rB 2,41t~
,xt:ý C=!Wr =
4- FLbie 2r- 6-. 5 toTa i w 2~4 ir Lh±- M== Saea P1Sa-iC 6zi-m sxg C~ivru- yýpe
ofsas s~ow= t-- F:C=e I-
5. Sa~icwvm ag==& ý'i roa~mg a--zd &4ar asdmIBy 2Mt zr =G*etr- Sao== z~tD
EIARD SURIFACE COAJT RONSNNAý
Toe f botn teýard Srnfagec ck~i.= to th ha~s cCM~is~ed of zieiti
ef- a s~r-rike of e! -ctro-sess -dckel Mceru- tre2=eýz) to tR bae tbi- qrtor to pva-L-& =I
R%ýge-ereme ab~ =fficif' Strt=CtB- to l ow ne ~ rýr ease e = ..
be:vhte Li-lasioan of hikerzt~e-~ (L e..- , 150OF or abee an q), sss -of-
DO=d !a.i1 '"eS *e'CancZ o'-~.e co=-ition Was c rnnab Zppartn~t M thet firs. -. f.
So4 rifrb sez O a~nd -E-1-ii -- on pcnit ~ r'~ ~c res we~re
obst-rvem on- arer half the Traibommeter and three-ha~l -cane specieins Thbe faiJu'2-e-s occmurred
prin-cipally duing th ie carb dsriding cycle or t"n C~xenc?: oera-tiw-
Titanin= samples incorpora-ving a -Xichbe-rmm strike tn ro-n-nickel s-Lrface coazing were szeý.cted
zo a v-actumn at 1675 -F temperature for four hocurs. Faiaiof ot '-e bond uinerface revealed
tie diffusion zone to be narrow with- th;e Nich-em a~aem acting as a barri-er to deep diffUsio-n.
Mficroh-ardiness; examination revealled a_ considerable reduction in hardness of the zone as conm -
pared with the base titaniumi. It was recognized that an improirenent migim be obte-in-ed by in-
creasing the dew-h of diffusion penetration since an increase in bohhardness and strength
M36-18
Figure 17. Shielded plating anode.
18
Ub:* an-~ e- 2o f t :adr -- 'ffI&e .rtovpm~r tbt ý=oc ~c± r Sa~i b
t ~c a~be~re
Mf -b-t-i
ce-ng:!,4- fffc- 4-F-igure a8.Plte t otn-u dhe Izwfu fsion ts specmens.
x~~tBan D.e 3, ifk-i
The efereOfdf=MC deI** 'z-s rebted to Mad- t~t3 7-M&S.r-WM-ntierl o- r
Cross-~t ati~~~ a.c~-e :be~t .aniý- rar L' imr, e-t-~e 6amt arie adeZe. -Strio e f-i
erazos ccrte z=Vsren ,ýft ZM=As oe-6 -<me f,- 72??dk Hii4r-]t alkr :zýt *-a=== :tm
Micape~te z- -= ,i~e-'- Mabk s Mae S - i ---- ~-~-i~~Ž
cpc~~a--D cfUSI* sei-mle 2nC:s RW, = of 4~ ff- =n
Cros d-f~sso O--wtT :e mnier-atre ?- Z-- te of)
Coating (%F) 1 3 6Diffusion depthi !:nches
Iron 1700 0.002 --- -- -
16715 0. 002 0. 0025 0. 00351600 0.001 0.002 0.003
1500 0.0005 0.001 0.002
1300 Nil Ni.1 0. 0005
Iron -nickel 1700o 0.002 ---
1675 0.002 0.003 0.004
1600 0.001 0.0025 0.0031500 0.0005 0.001 0.002
1300 Nil Nil 0.0005
20
f
Tau* mm MIL5Zw ~ *~
__.En.. 1S E51.- -" 5 - - 151-. si. - - - E . "s. 1
. SEe!Yc• • u !zOi . a --- E 5 5 3--- ! 2.
15ZO- 3 --- 15-L .5
!52~ .- 0 - - 151-3 14ý 7
U e-e, . £ "..5 --- 70. 5 --- I6.Yield stre=rsh, ksi P38..! --- 162.0 --- 157. 5Elongatzien, 15.3 --- 13.1 --- 15.0
"" -"--11- - -- ---
,. " .• . "* .. V6 :. - ;•-z - -o.- "
-0. - _ *
500)X 500XFe Fe-Ni 50OX
M~6-20Figure 19. Vacuum diffusion zone.
2,
£t.U1-z~wtxk_ 5 cb taw ~z=& £=IIW M L*-tL =Lum Emuthwxt af =u L 1i -Lnta
Iran Aqn 44W Titanium
Figue 20. EkeCtrwa micrqwobie Satu& it UrM emti amd fib-i~
FeNi FeNi
14t-.
~~i f1"2r. Ti Ti
7326-22
Mgn 444X I ron Nickel Titanium
Figure 21. Electron microprobe study of iron-nickel coating and titanium.
IM:M ad~uaiar dev-, c a~~i~w *4= ier mu 5Ufa3ri cionrastt- zore*3w aart1 M& _-vMt ontra CIOMt4 :Mir12.i
Mh~ m._-a'x G N.E.-ar rn-.'M MEX-m of1~ =ek : Wlo~ ~us =Fivt. foo tqaiwrt-4 ThsZC-
-r2.z~rb ie= 10t=UM7 ar BMW'F, b a.r~t sfiAxv ther-~l :~avs ruto ns7i
ZWr.rrede :ahe Crc-rk=4 ~ Qerfc thbe v~E= la~zk. Glas~s bt'eaXd Peenarg W-ts Msted stcb-
seqz-sr :o :_Le krtraa' daf:n Cyrcle (1009F) 2zvd s~-eC- to e2ct+i gmFL
Ahbaa gkzass ibezod eC-aarig !-I. rk'y5dced; the Cra,_CkLag* ze~ei. he cea -
dition coabm __ be elMCd !Btcrzse off thins ca~driow, farzter heý-M Nicheti-i plzate &w-rop-
Mrenz oa ge:r~s -zz_ a. s~n~l.Frt~rtoret, =z t. argissa! effforts to lx~d tr~an 5d iron-=aekel
electrodeiOSILS To thoe ti ;-aint 2!10oý tesz sz caneemS. ý_ electroiess nij-:kel cm-- mag 0- 1 to 0. 2
=il thick was Used. 7Tr.4 tNiI ~Chiti l~ proCteSSsec Z a~o ine~.. tra-atec (aS pre-
vicash- 6described) were lighatl, firne gri: -me, blastee -;aýi lcocci~~ ac-ivaed prior- to
s~erslor ir. 1ne IrO' an-; aroxi-nckel pl-tazng s-lutlanrjs_. T-he s-Lste= worked wc-l;it uil the
htgh~er zenniperature heat tre-ý_mei'ts d rapid quen-ches -vere usfed. r-e -t was learned timt
tle diffused Nichenl would not withstard the thermal shocks.
Earlier work b~- GM Researchi LaJhorztories had deter-nined f;aror-Able processes for the harden-
ing of iron deposits b%> suitable heat treatment, 1)eposiis of iroe.-nickel having good harden-
abilit:. were plated on the regular sections of the Tribornetr and three -ball-and -cone test
specimens- The typilcal irregular sections of gear teeth resulted in rich deposits of nickel to
be deposited' on the gear tooth root areas. AXlthough Phase I gears were processed with iron-
.nckel plating, it was found that thei nickel rich areas did not respond favorably to the heat
treatment process.
I-nase 11 and III gears .ver. i - n plated, therefore, efforts were made to provide opt imumn heat
treatment for the iron plated titanium combination. A review of the heal processes follows.
Nitride Proress
ANtte-mpts to h~jrdfn thc iron platc !.,; nitriding were unsuccessful. Nitriding v~as attempted at
lico to I1!00'1 ..rd with %%trious atmosphere changes, hut suff- 'ant surface h. rdnt-ss was not
a c-om plished.
23
=Cl;1 to (:ade-r- ýardk'= amt retzat-m t.fre ptýQ*-ttw- ;k 5a t
T'zi ~i~rtsar ~e~~tnn. _ ttem-iaZre- to - -'st-* :H&e !Ca~ ~t of !a& care
~ ~.-'--~e~ -- ~~as ptcv'-'- proc:SS Carbriziag pron'lde--
~~i- -! eSe SUM-rM-Me a h -rume~s after - oCcSSi t= = z-e m excess off 1E59W..r.L& Co-e M*04Z 2zk zha ar ocessip -2 Wf~Oct -r --6itora. h.'aZt tft-- stpWE
~V ~ZL~Kh rtd¶=, Ca-Se tacis i- e- , Ca~ixfrEZed LO cc zt1jeX) zar4, :eeoe a
F~ro-=-*~~Lr!rg the ao.'irie process orOm-rded suhstaniz snrowc-nern~ tL' t~te hardn~ess
oftro 'W i~e. ~~i~ !lt as accor-ttis-hed 2t 16506F-. The use of thiis t~rtr
__I-, a~ C-.enci :Povided OctInmam case hardnesz of He 55 or higher. Th,-e I 65Oz F leniperat-are,
h',meyer, o):-Oed L~z~tawe izh the ziiardarn tase aIlo'm; stre:gth pro- eries of th i-wt-we:7e drastilcaiv redu~ced-. Reduct-ion of the tem-peratu!-e to 1550'F proved-, o be nnore compat~ibe
-- J
Mg: n: 5M W.n
42
sith the tiftan and stil provided the necessar? hardants in the case. Following an oil
opewah and ternpoing the iron specimens were 1(c 55 to 57 (microhardness). To establish
eamplew beat treatmenu parameters for boh the ir o -ated case and the titanium alloy core,
the foRlowing beat cycles were evaluate, rith results as shown in Table IV.
The 1550OF12.25 hr cycle was selected to achieve ha-.-. •ing of the complete iron plate without
producing excessive carbon at the iron-titanium inter fa: t. Typical microsections are shown
in Figure~ 23.
T•_e finalized carboitiride proces is as follows:
0 Pre-eat gears to 500"F
* C-2rbonitride at 1550"F/2. 25 hr:
o 35 min- 1. 5 ft 3 propane gas
2.0 ft ammonia
Table IV.
Carbonitride surface hardness-de , h.
Temperature Time Surface hardness Depth
(OF) (hr) ( 1 5N) (in.)
1750 6 89.0
4--
1700 6 .. .
4 89.0
1650 6 90.5
4 90.5
1600 6 90.5 ---
4 91.0 ---
1550 6 88.5 ---
4 90.0 ---
3 91.0 0.017
2.75 91.0 0.016
2.5 91.0 0.016
1550 2.25 91.0 0.015
2.0 89.0 0.010
1.5 89.0 0.0085
0. 75 88.0 0. 007
1500 6 88.5 ---
4 91.5
• 25
RePo •lable coPY-be~st 8
i ./
1.5 hr Mgn 2.0 hr 7326-24bOox
Figure 23. Typical carbonitride of iron on titanium.
9 90 min-1.0 ft 3 propane gas
2. 0 ft 3 ammonia
o 10 min-generator gas
0 Oil quench at 350°F
* Temper at 350 0 F/2 hr
* Air-cool to room temperature
0 Temper at 3500F/2 hr
This process produces the gradient shown in Figure 24.
Temper Process
The effect of temper on the case hardness of iron and iron-nickel is shown in Tables V through
IX. The effect on the core properties is shown in Tables X and XI.
The finalized process used on the final gear sets was the 2. 0-2. 25 hr cycle at 1550'F tempera-
ture followed by two 350°F/2 hr temper cycles. The final properties ace shown in Table XII.
26
5045 - •C ting interface
S40
02 4 6 810 1214 1618 2022 24Depth x 0. 001
326 -25
Figure 24. Heat treatment hardness gradient.
Table V.
Effects of low temperature treatment on surface hardness (H 15N).
Carbonitride cycle Oil quench + Low temp-- i00°Ff/ 1 hr
Temperatare Time 350°oF/1 hr temper plus second 350°F/1 hr temper
(°F) (hr) Fe Fe+Ni Fe Fe+Ni
1700 6 89 83--84 92--93 91--91. 5
4 89 81--83 92--93 90--90.5
1650 6 90--91 87--88 92--92. 5 90--91
4 90--91 83. 5--84 92 90--91
1600 6 90--91 87--88 92--93 91. 5-92
4 90--92 85--86 92--94 90. 5-911550 6 88-89 89 90-91 90
4 90 88.5--89 91--93 90. 5--91.5
1500 6 88-88. 5 87 90 89. 5-90
4 91--92 86.5--87 91--92 90--91
27
Table VI.
R15N hardness values of specimens given final high-
temperature temper ireatment of 450 0F.
Carbonitride cycle Ternp.r time (hr)
Temperature Time 2 4 a 12 16
(OF) (hr) Plating Hardness
1700 6 Fe 92 91 91.5 91 91
1700 4 Fe 92 92 91 91 91
1700 6 Fe-Ni 90. 5 90.5 90 90.5 90
1700 4 Fe-Ni 89.5 89.5 90.5 89 90.5
1650 6 Fe 91 91 91.5 90.5 90
1650 4 Fe 92 91.5 90 90 90.5
1650 6 Fe-Ni 90.5 90 90 89.5 89.5
i650 4 Fe-Ni 90 89.5 89. 5 89 89
1600 6 Fe 91 91.5 90 90.5 90.5
1600 4 Fe 92 91.5 91 91 90.5
1600 6 Fe-Ni 90.5 89.5 89.5 89.5 89
1600 4 Fe-Ni 89 89.5 89.5 89. 5 90.5
1550 6 Fe 89.5 89.5 89.5 89.5 89.5
1550 4 Fe 91 90.5 90.5 89.5 90.5
1550 6 Fe-Ni 90 89.5 89.5 89 89.5
1550 4 Fe-Ni 89.5 89.5 89.5 89 89.5
1500 6 Fe 90.5 89.5 89. , F9.5 89.5
1500 4 Fe 9! 92 90.b 90.5 90.5
1500 6 Fe-Ni 88.5 88.5 87 89 88.5
1500 4 Fe-Ni 90 89.5 88 89 89.5
Note: Heat treatment prior to final temper treatment.
Diffuse 1600°F/3 hr + carbonitride cycle as indicated + temper
3500F/1 hr + -100°F/1 hr +350°F/1 hr.
28
Table VII.
R 15N hardness values of specimens given final high-
temperature temper treatment of 550*F.
Carbonitride cycle Temper time (hr)
Temperature Time 2 4 8
(OF) (hr) Plating Hardness
1700 6 Fe 89 88.5 88.5
1700 4 Fe 88.5 88.5 89
1700 6 Fe-Ni 88 88 87.5
1700 4 Fe-Ni 88 87 87.5
1650 6 Fe 89.5 88 88.5
1650 4 Fe 89.5 88.5 88.5
1650 6 Fe-Ni 88.5 88 86.5
1650 4 Fe-Ni 87.5 88 86.5
1600 6 Fe 89 89 88.,5
1600 4 Fe 89.5 89 88
1600 6 Fe-Ni 87.5 88 87.5
1600 4 Fe-Ni 88 88 87.5
1550 6 Fe 88.5 88 87.5
1550 4 Fe 89 89 88
1550 6 Fe-Ni 88 87.5 87
1550 4 Fe-Ni 88.5 88 87.5
1500 6 Fe 87.5 87.5 88
1500 4 Fe 89.5 89.5 89
1500 6 Fe-Ni 86.5 86.5 85.5
1500 4 Fe-Ni 87.5 86.5 86.5
Note: Heat treatment prior to final temper treatment.
Diffuse 1600°F/3 hr + carbonitride cycle as indicated +
complex temper 350oF/1 hr + -100°F1I hr + 3500F/1 hr.
29
Table V11L
R 5N hardness values of specimens given final high-
temperature tcmoer treatment of 6500F, 7500F, and 9000F.
Carbonitride cycle Final temper
Temperaturc Time 670°F 750IF 900°F
(OF) (r Plating 2 hr 2 hr I hr
1700 6 Fe 86.5 86.5 79.5
1700 4 Fe 87 86.5 79
1700 6 Fe-Ni V5.5 85 80
1700 4 Fe-Ni 85 85 80.5
1650 6 Fe 86.5 86.5 79.5
1650 4 Fe 87 86 80
1650 6 Fe-Ni 85 85.5 80
1650 4 Fe-Ni 84.5 84 79
1600 6 Fe 86 86 79.5
1600 4 Fe 86.5 86 80
1600 6 Fe-Ni 85 85 77.5
1600 4 Fe-Ni 86 85.5 79.5
1550 6 Fe 85.5 84 78
1550 4 Fe, 86.5 86.5 78
1550 6 'Fe-Ni 85 84.5 79
1550 4 Fe-Ni 85.5 84 77.5
1550 6 Fe 85 83.5 77
1500 4 Fe 86.5 85.5 79
1500 6 Fe-Ni 83.5 83 78
1500 4 Fe-Ni 84.5 83.5 78
Note: Heat treatment prior to final temper treatment.
Diffuser 1600°F/3 hr + carbonitride cycle as indicated +
complex temper 350°F/1 hr + -100 0F/1 hr + 3500F/1 hr.
30
Table MX.
R 15N hardness values of specimens given final high-
temperature temper treatment of 5000F.
Carbonitride cycle Temper !ime (hr)
Temperature Time 4 12 18
(0F) (hr) Plating H!-ardness
1700 6 Fe 90 89.5 88.5
1700 4 Fe 91 90 89
1700 6 Fe-Ni 89.5 88.5 88
1700 4 Fe-Ni 89.5 88.5 87.5
1650 6 Fe 90 89.5 88.51650 4 Fe 90.5 8o.5 88
1650 6 Fe-Ni 89.5 88.5 88
1650 4 Fe-Ni 88.5 88 88
1600 6 Fe 90 90 89
1600 4 Fe 90.5 ... ...
1600 6 Fe-Ni 89.5 88.5 87.5
1600 4 Fa-Ni --- 89 88.5
Note: Heat treatment prior to final temper treatment.
Diffuser 1600°F/3 hr + carbonitride cycle as
indicated + t-rnper 350°F/1 hr + -100 0F/1 hr +
350°F/l hr.
31
I*Ta TPe -X.
Tezsi~ ~ierues ~ersi ate 60SF arbowiridead€ 350 to 950-F tenper.
Only the fi-I temper time Processin
a wd temperaures being Temperantre (OF) Time (hr)
varied as indic2-d.1 1600 3
Slm cool
1600 (Simul2te carbonitride)
Oil Vuench
350 1!-100 !
350 !
Final temper as indicated
Ultimate Yield
Temperature Time strength strength Elongation Reduction of area
(OF) (hr) (ksi) (ksi) r ) (M)
950 2 203.2 184.1 6.5 11.6
750 2 193.8 169.5 11.9 24.8
650 2 168.4 154.8 11.8 25.0
550 12 171.5 163.1 11.0 23.2
550 8 162.6 158.4 14.7 30.0
550 4 151.9 146.7 17.0 30.4
550 2 152.9 144.5 14.6 21.9
500 18 159.5 157.8 16.0 38.5
5 00 12" 157.3 153.6 16.3 30.2
500 8 156.6 154.8 13.5 23.3
500 4 160.4 154.8 14.0 27.0
500 2 150.1 142.5 19.4 23.2
450 24 151.9 148.9 16.8 33.6
450 18 150.9 148.8 19f. 35.6
450 2 149.3 141.9 16.0 21. 7
350 2. 149.9 138.0 17.6 36.2
Notes: Hardness values of specimens below the line meet or exceed R 15N88
minimum value for iron cases.
'Optimum cycle for titanium core strength and iron case hard.**No low temperature treatment (-100°F).
32
Table XL
Tecsile, wopmutes aifte siV~ed 155O'? carban"Ideand 350 to $9S0WF te~per.
00ily the ri~ma temper iti Proe~iesirand temper~eres beiag Tempez-znwe (-F) Tirme V=)
aried as iii-cwed.1550 3
slow cool
1550 5Cimle carboafride)
350 I
-100 1
350 I
Final temper as indica1ed
Ultim2te Yield
Temperature Time stre•gth strength Elong•tion. Reduction of are2(OF) thr) (ksi) (kS) r") (M)
950 2 193.9 167.7 7. 7 8. 7
750 2 162.9 147.9 17.7 32.6
650 2 149.3 142.7 17.4 28-6
550 8 149. 9 143.2 22.1 29.4
550 2 149.3 142.6 16.3 28.2
450 8 149.5 145.3 17.1 37.1
450 2 150.3 145.6 15.7 30.3
z,50 2* 150.3 144.1 18.5 40.0
Note: Hardness values of specimens below the line meet or exceed the R 15N 8 8
minimum value for iron cas-s. Iron-nickel values are 1-2 points less.
*No low temperature treatment (-100 F).
SURFACE LUBRICANT COATINGS
Solid surface lubricant coatings offer a means of preventing sliding friction damage during
periods of limited lubrication or failure of the primary lubrication system. The solid lubri-
cants are of great importance during the original break-in running of near assemblies because
of their ability to shear internally and to move and accommodate to surfact. discrepancies.
Furthermore, they are very adherent to loaded surfaces and have the capacity to retain oil
films which can supply lubrication for appreciable periods of time after failure of an oil supply
system.
33
Tab*e ..JL
3 !-4& 3 45... " .7 E-0.--5O. 256 ..,.'
5 1483 * ,;3 ... 1.•8
r .- M,3 14:_ .
8 ;48..5 W-G. z-.8
Average !4-. 2 143.6 7." 13A
Core !iard-ness (tizaniat) =Rc37_
* Th7-e solid surfiace subrica...ts chossen for tnis programn had de~sr~e zi.eof gooc
prop - ties at ambie-n a- d e!ev•-ed tem:e.:-aures.
Dow Corning 1-34M? L-FML-4!)
This solid surface luhricant is a developrnent of t;h- Air Force .Mlaer:x-4 s Laboratories which
has been licensed to Dow-Corning for manufacture and s Aes. It c.,sz=s of nolyieen.,-
disulfide a.d antirmony trioxide in a resin bince. and was spra% gun applied. r-i&ms of *.he
coating in thicknesses of 0. 5 to 1.0 mil were applied "o Trihometer, three-ball-and-cone,
and Ryder gear test specimens. After spray application, the films were air cured at 350'F
temperature for two hours.
Silver - Niobium Telluride Ag-NbTe2
This solid surface lubricant which is applied electrophoretically is a proprietar'. development
of Detroit )iesel Allison and is the subject of current patent proceedings. The frie particles
of silver and niobium telluride are codeposited at room temperature to a thickness of 0. 2 to
0. 3 mils and require no further treatment.
Teflon + Molybdenum Disulfide (Teflon-MoS 2 )
IFinely divided particles of Teflon dnd molybdenum disulfide are electrophoretic-all., codeposited
to a thickness of 1. 0 to e. 0 mils. This also is a proprietary process of Detroit I),csel Allison
and is a aubje t of current patent proceedings. The coating was tested on Tribometer speci-
mens onl'y. Its properly of extruding under pressure and tniling up outside the lo.td pattcrrn
made it less desira±ble for the three-lhdll-and-cone and |ixder gear surfaces.
34
Th* gears were Y soi to fe.ate cc th Rue gar tster-irtM 3.. 5•- Cemer d1as re
Two sets were desigsttbi are deszemaeed as P"w I apc Mase Ui as 25 x ears..
PHASE I GEAR DE5JG!N
Fse * gears w fa es tid o r .1360 pst bsfZiaM C= SZC*SS hSed Wn. Se*I O Of
elasicizy of 30. 0 X 106 psL. The e iwafii coata1 stu es- fer :xiuasmi _s T_ v.,00 psi based
om a medm~ c 16-5. Jv, 106 PSI- TbC be rtZi-&- Stres eSStU9 ti 9, t d Efo -- ~~-t-.RL
WT RP
whiere:
p=Poisson's rat!.:,
E =Young's modui s.2,f e~asticity n'x IC .si
W, tangential load - 667, lb# pressure angle al pitch di~a- 25 :egrre,
Fe effective face wid _h = 0- 360 in.
RG pitch radius-gt~a.-" = 1. 750 in.
Rp - pitch radius-pinion - 1.750 in.
TQ torque = 1058 lb-in.
The face width of the gears was modified to accom.- c-.':e -. e arxiAl travi it- t e loading mech-
anism of the Ryder z ig, thereby providing full enga-, :nit (.. the r. rr-)w gea- ti , ughout the
operating range of the test schedule.
The tooth thickness of both gears was modified to Mai1 .;i.. bal;.nced bendir-g delection between
the narrow and wide gears. The Lewis stress equatic used *o -aicu'ite th.• n di-., stress
with the load applied at the high point of single tooth co:,' c: (OIV TC) is as follo•.s:
3TQ
D V min XI PSTC
35
x factuor- x: EIpsmT
* Phas-e U a0d 111 Gear Design
ie&= : Pha tse gea =rs Y iso~ sb-m Figue vmar 0wre detn.w riue 8,C-i!i
coTab.t s.ress bse. o. .he s.eel rotiuu of elasticit., of 30. ; , !0• •.d a !'o1sao.w s ---.tio of
0. 30. Th"e 185. 000 :si st.ress is eqii'-i-.ne.• t.o 1-40. 000 •si hertz cont•act for tita•rdu.n. i-i-'. a.mnocal~us of elasticity of cc.5 " 10" and a Posson's .- o of (. 3. "-is st ess ts de.e.o•-d oiaC etlfectiye f -ce tidh of 0. 250 fis&,d tig oa r he a'r " et riga- n- 14, 0 7.
5 piessure angle 40.004Distance over bro 0.1128 mo- pins '-3. of1916 -a.0000
Roof dia 3.263 ±O0.Oi3Pilchdoia'-3.5000Active PrOfile oulside - 3.33301035 diG
I Referenceco-sArc toobh thickness ao PD -0.1 39416 ; O0.001
Dia--fetTC 0.00- to 0.010 .ack0ash with mating geOr on standard centersiv Base ircle dia 3.1720 pn31 0.526
Ro 9 0.5-6
P~hda- 3-50.47
--rc -thickness at P-3.64
Figure 25. Bending stress geometry. Figure 26. Phase I wide gear design.
36
00L9' .1
;lmedie - ~ tie
F•,ure 27. Phase I narzo gear desige..
Tabh XHL
!•.ase I test schedule- surface stress-
Surface stress a- pitch
Test time Total cycles Torque Normal toorth line (psi) (Hz)
(hr) (X 106) (lb-in.) load (1i) Titanium* SteelF
10. 0 8.4 470. 3 296.5 80, 000 105, 928
10.0 16.8 530. 9 334.7 85,000 112,549
10.0 25. 2 595.2 375.3 90,000 113, 169
20.0 42.0 663.2 418.1 95,000 125, 710
20.0 58.8 734.9 463.3 100,000 132,410
20.0 75.6 810. ? 510.8 105,000 139,031
20.0 92.4 889.2 560.6 110,000 145,651
20.0 10M.2 971.9 612.8 115,000 152,272
20.0 126.0 1,058.2 667.2 120,000 158,892
"-Young's modulus--titanium 16. 5 X 106; Poissoi's ratio-titanium 0. 35.
Young's modulus-steel 30.0 / 106: Poisson's ratio-steel 0.30
37
Table XIV.
Pae I teat ,wdi-ed s-ess.
Beaing suvess at Hp c Bending ea- at Ha pTc'
Test time 0i) ToWa pinioe O-.)
04) pinion Gear _______
10.0 8, a2 8,317 0.00041
10.0 9,959 9.389 .00046
10.0 11,165 10,526 0.00052
20.0 12,440 11,728 0.00058
20.0 13,784 12, 995 0.00064
20.0 15, 197 14, 327 0.00071
20.0 16,679 15, 724 0. 00077
20.0 18,230 17, 186 0. 00085
20.0 19,849 18,713 0.00092
HPSTC-h& poin silWje tooth conaci.
20Dwron hertz
!stress150-
50 Senrdingstress
0 5M0 100O M 2000 2500
Normal tooth load-PPI1326-28
Figure 28. Subsurface stress distribution.
3S
D -
W All am~iI are in nhxW.C.02Y4
to- S~C•
26 7 003 0.030S_- 0-02 326-29
Figure 29. Phase H narrow gear design.
Gear todhspaeandsplinetooth to be inline within OdG 5 olin
0 0396 ref
D - etion 0-DNote. All dimensions are in inches.
0.022- 0.012
2. ODO -re! 0.0350.03045 deg 07326-30
Figure 30. Phase U- wide gear design.
31)
To provide a reduced Lewis bending stress of 17, 849 psi, 6.0 diametral pitch, 21 teeth, and
25 degrees pressure angle was selected. The minimum profile contact ratio for this selection
is 1.362. The selection of this gear tooth geometry reduces the total tooth Hertzian and Weber
bending deflection to 0. 0009 at the high point of single tooth contact for the maximum load con-
dition to produce the 185, 000 psi Hertz stress.
The face width of the gears was modified to accommodate the axial travel for the loading mech-
anism of the Ryder rig and thereby providing full engagement of the narrow gear throughout
the operating range up to the design test objective of 185, 000 psi Hertz contact stress.
The load schedule and related data for the Phase II and III gears is shown in Table XV and
Table XVI. Complete assessment of the 6. 0 diametral pitch gears is made by DDA spur gear
computer program and is shown in Appendix I.
Table XV.
Phase II and III test schedule -surface stress.
Surface stress at
Test time Total cycles Torque NorlAal tooth pitch line (psi)
(hr) (X 106) (lb-in.) load (lb) Titanium" Steel**
2 1.68 176.3 111.1 60,000 79,430
2 3.36 239.9 151.3 70, 000 92,650
2 5.04 313.4 197.6 80,000 105,910
2 6.72 396.6 250.1 90,000 119,150
2 8.40 489.7 308.7 100,000 132,380
10 16.80 592.5 373.6 110,000 145,640
10 25.20 705. 1 444.6 120, OCO 158,750
10 33.60 827.5 521.8 130, 0(;0 172,000
10 42.00 959.7 605.1 140, 000 185,000
"*16.5 X `16
**30. 0 X 106
40
Table XVI.
Phase U and III test schedule bending stress.
Test time Bending stress HPSTC Bending deflection HPSTC
(hr) (psi) total pinion (in.)
2 3,279 0.0002
2 4, 462 0. 00032 5,828 0.0004
2 7,377 0. 0006
2 9, 107 0. 000710 11,019 0,000810 13,114 0.001010 1,391 0.0012
10 17,849 0.0014
41 (page 42 blank)
SECTION IV
GEAR %1ANU'CICTURE
The manufacture of hard coated titanium gears consists of 35 manufacturing operations re-
quirmg 24.0 hr set-up time and 30. 3 hr manufacturing time for Model Shop fabricativn. Manu-
facturin•g details sre described in the routing sheets shown in Appendix 11. Figure 31 shows
dre gear too!h profile as manufactured.
Process sequence for Phase !, I1, and IIl gears is as follows:
0 10ob
* Preplate grind (Phase I and II only)
* Plate (FeNi for Phase 1, Fe for Phases II and I11)
* Diffusion bond
* Preheat treat g- nd
* Carbonitride
* Finish grind
* Lube coat
The involute profiles were full form ground using cams manufactured by a numerical control
(NIC) system developed at DDA. This grind process ensured plating uniformity ol the entire
root fillet and involute profile.
Process dimensions are shown iD. Tables XVII and XVIII.
STooth
0.017 min0.001 min
0.002-0.0030.012-0.013
Plate
Preplate grindFigure 31. Manufacture of gear tooth profile. Preheat
treat grind
Finish grind
43 7326-31
:L _______
Table XVII.
Phase I, H, and III narrow gear process dimensions (in.).
Arc tooth Root fillet FacePhase Dimension over pins thickness Root dia Outside dia radius width
0. 3631 3. 750L0. 002 --- 3. 250±0. 005 3. 656±0. 005 ---
0.373
Hob II 3. 875±0. 002 --- 3.110+0. 000 +0.000 0.2603.803 0.-60
-0. 005 -0. 005 0.270
+0. 000 0. 266III 3.875±0.002 --- 3. 100±0. 005 3.803 " ---
-0.001 0.268
SPreplate +0. 004 0. 130 0. 363PrI 3.704 -0 3.234±0. 005 3.656±0.003 0. 048grind -0. 000 0.132 0.373
S+0.006 0.238 3.0700+0. 000 +0.000 0.075 0. 260
-0. 000 0.241 -0. 005 -0. 005 0.085 0.270
+90 000 0.240 +0. 000 +0.000 0. 079 0.266III 3.852 " 3. 075 3.808+0
-0. 003 0.242 -0. 001 -0. 001 0.085 0.268
1 0. 025 minimum
Plate II 0. 020 minimum
Tfl G. 017 minimum
Preheat 774+0. 005 0. 165 694+0. 000 0.405S 3.77 - 3.273±0. 005 3.69 0. 032treat -0.000 0.167 -0.005 0.415
grind920+0. 006 0. 278 +0.000 +0. 000 0. 058 0. 300
_-0. 000 0. 281 -0. 005 -0. 005 0.068 0.310
111 3.915+0. 000 0. 277 3.106+0. 000 +0. 000 0. 064 0. 294III .91 - 31063.839 -"
-0. 008 0.275 -0. 001 -0. 001 0.070 0.300
Fia 0 0 .17+0. 000 0 0Final 1 3.759 +0.004 0.157 3,263±0.005 3.694 " 0.034 0.400grind _-0.000 0.158 -0.005 0.410
0+0.006 0.268 3 +0. 000 +0. 000 0.062 0. 290I! 3902+0 -0 6 3. 100 3. 833 " -
.-0.000 0.271 -0. 005 -0. 005 0.072 0.300
III 3.904+0. 000 0. 268 4-0. 000 +0 000 0. 067 0. 290-I .0. 00 • 3. 100~o 00 3.833~~ 00"-0.003 0.269 -0.001 -0.001 0.073 0.294
44
"F Table XVIH.
Phase I, 11, and M wide gear pracess dimnensi-ons (in.).
Arc tooth . Root fillet FacePhase Dimension over pins thickness Root dia Outside dia radius width
3.680±0.005 -'- 3 250±0. 005 3.656±0.005 0.379
• 0.389
+00000 0.356
Ho I 3.875±0.002 -- 3.10I0±0.005 3.803 --
-0.005 0.366
+0. 000 0.210 +0000 +0.000 0.097 0.370
1In 3.79088 -- 3.075 3.808 1- .. . .-0.003 0.212 -0.001 -0.001 0. 0.372
I . 0. 025 minimum
*i
Plate * I0. 020 minimum
III 0. 017 minimum
Preheat +0. 004 0. 146 +0.000 0.521I 3.76581 3.273±0.005 3.694 0.032treat -0. 000 0.148 -0.005 0.531
grind+0. 006 0.248 +0. 000 +0. 000 0.075 0. 396
ii 3.863 - 3.110 3.843-0. 000 0.251 -0. OG5 -0.005 0.085 0.406
I 1I 3.8 0000 3.0254 3. 833+0. 000 0. 082 O. 400
S-0.003 0.249 -0. 001 -0. 001 0.1088 0.406
Final.02 mniu
Final2+0.004 0.140 0.000 0.516grind -0. 000 0.138 3.-0t0 0 .60 0005 0, 0. 0526
11 3.8+0. 006 0.'146 3.0 8 +0. 000 3.694+0. 000 0.086 0. 386
-0.000 0.241 -0.1005 -0. 005 0.090 0.396
+6. 000 0.238 +0. 000 +0 000 0. 084 0.396IIi 3.847 3.100 , 3.833 --0. 003 0.239 -0. 001 -0. 001 0.090 0.400
45
Typical inspection charts of manufacturing control are shown in Figure 32.
Manufacture of iron coated titanium gears revealed a strong tendency for the coating system to
crack during processing. A number 13 BT glass bead peen at 40 psig was implemented to pro-
v.ide compressive stresses superimposed over any residual tensile processing stresses. This
procedure also tends to unify stress distribution across the gear surface. In addition to elimi-
nating surface cracking the peen operation improved the surface finish to 16 rms. Further
improvement in the surface finish was accomplished by the Hone operation which reduced the
finish to approximately 4 rms.
Electron probe and micrographic analysis of gears with defective plate revealed residual sili-
cone carbide particles at the iron and titanium interface. These particles were suspected to
have come from the blasting or cleaning operation prior to plating. Several tests were made
and aluminum oxide was selected as a replacement media. Subsequent examination revealedvery little aluminum oxide adhered to the gears and what was present appeared to disperse
ODB- -r
S[-0.0002 in
SI"Pitch'-.....-
LPSTCtca1
7-,
•, A,
"" ..0.~~0002 i n ' " .
Typical profile chart- Typical tooth spacing chartnarrow and wide gears
OD - outer diameterODB - outer diameter breakHPSTC - high point single tooth contactLPSTC - low point single tooth contactAPD - active profile diameter 7326-32
Figure 32. Typical gear inspection charts.
46
during thec vacuurm dififusion treattinen-. The silicon carbide was no longer in evidence a-nd the
- percc-ntage of defective tivtanitum to iron difffusion bonded gears dropped to near zero.
Postheat treatment cr-acking was primarily Laused by grind induced stresses which were cor-
rected b -modification to low stress grinding procedures consisting of reduced grinding w-heel- speeds, softer grade grinding wheels, a-nd reduced infeed rates. This process was followed
by glass bead peening of t'he parm.
Finished gears are shown in Figures 33 and 34.
-~ 1
P. -1f4q
Figure 33. Phase II finished gear set.7364
47 (Miagc 48 Mi~rk)
TESTL'XGIA-IALVSiS
T'-t. T rio..e:er, designtd an.d con:.ruczed b DDA, permits the determination of static co-
e'-"IL~t- w: o. f-rIction as weli as E'.' c. .!ile of the vrea-r surfaces- This rig consists of a loading.
S:- s:t. , S-Z:orL.•. s.pei.m..en L.I.o*:r, os:-UL-.ing test shaft, and recording instrumentation.
.r .. 35 is a front vi-ie' of :he -es: rig wit;, its test parameters.
-Fr,'Lo=eter rozt ing and fiu=:ed -est secimens w..-ere fabricated from Ti 6A-2S-i-4Zr-6.Mo,
p!z-td ".,:d inis.ed as shown in I.!gure 3; and Figure 37 to maintain 0. 015 inch plate thickness
I. c 55-53 surface ha".rdness.
"Temperature-ambient
"Applied load (static)-100 lb
Angular motion-60 degrees
Oscillation frequency-16 liz
Test time-1000 cycles
t2 3 6 --
Figure 35. Tribometer test rig and test parameters.
N4
ARom - 33 M516 Beor0e .htng-f 0ish
0.515 , Indb 0±0.OO1 /lslbt
AbskMafkD and bothAfter coating-finish end faces during 0. 750 in.grind to L ODD U0.001 coating ±0.010 in.
7326-36
Figure 36. Trlbometer rcbati specimen.
300
±301
0.750 ]16±0.010 1 r 164"
±,O, 0. 600 in.
-. L0 Finish grind requirement +0.6010Si 0.500 on all surfaces except this±0.010 and opposite
Coat this surfaceprotect all others -4 11] 7T26-37
Figure 37. Tribometer stationary platen specimen.
50
•% , L . . .. . ...... ..
The fouOWAig test SecieM Stu were tested to denwmine the 09= mtenal and lIIcaat_
Ptlitinz Nome AC-INbTe, Te-IUS, vAEr,%S6 3
Irom-Ticke~l 6 6-6
Electroless nickel 6 6 6 6
TyýpiC2l I rihnometr test specimen set is shown in Figure 38.
Electroless N-ickel (N-%idimem) Hard Coating
The Ti 6Al-2Sn-4Zr-;Io, Tribometer cvir~lners aird pzat1en3 were plaed with 18 to 24 mils of
electroless nickel (Nichem), thernWIav diffuWea a1 lOOOOF in vacuum, and finish ground to 15
inils of hard coating with a hardness off Rc 55 to 58.
Because of the extrusion and piling up around the wear scars of the Tribemet-er teAts of the
electroless nickel (Nichem) hard coatings, the electrophtretic Teflon-NMOS 2 surface lubricant
coating was dropped fr( n further consideration for this programi. Accordingly, Tribometer
tests were performed with carbonitrided iron and iron-nickel alloys on the Ti 6A%1-2Sn--4Zr-
6110~ in the finish ground condition and with the spray-coated AFML (DC 1-3943) and the electro-
phoretic: Ag-N-bTe 2 solid lubricant coatings.
Carbonitrided Iran and Iron-Nick-el Hard Coating
The program originally included the use of diffused electraless nickel (Nichem) as the bonding
medium for the iron and the iron-nickel alloy hard coatings. Unfortunately, by the timie it wras
7326-38
Figure 38. Typical Tribometer test cylinder and platen.
51
iii-M, "I'-
01=e hh =ca Sarke LWBze4. thefoe VMS ded to beat treat tib'e- spetipens toTale L if Sui =M"t 2tq=e boa we :.ec scr a m Ib for the TrKWoftt tests.
Pw~~ i.u tcc tbws ae ob rue; hXr~, 2S te teuSM~ bereM it w~uas e~d~ umha the
bedng syste voald rze s.rtive the Trzbeter tests. Figure 3-2 illmstrafes the faiinres
~eiece:the veak bo aild E21- ME applied 102ad t2- I_~ E"COatiuns fatigued and Ir2C-tc"!d ~ strp -i -y Laie in the pw Ygram it w-as then aecessary to produce iron a--d iron-
rCiekel 2110T Tr70 erW SPeCi-meMS WEi X hed been beaded bv thee thermal difso procedu~re..
Figure 40 and Figare 41 show the eatrc-e li-is of uwear scarr profiles; with their test speci-
Tanle XMX is a summaryt of the u-ear scar deptrhs and a summary of friction tests is shown inFigure 42.
Tribometer Test Conclusions
* Tribmeter testing reveals little difference between vacuum diffasec, double tempered,
carbonitrided iron and iron-nickel as hard coating materials.
o The electrophoretic Teflon-iMoS2 surface lubricant shows good properties. Howe-er, this
lubricant's appreciable alteration of surface geometry by extrusion displacement make it
a questionable choice for highly loaded lubricated surfaces.
* AFML-41, surface lubricant prov-ides optinum protection for all of the materials tested.
* Carbonitrided iron + AFML-41 produced the least surface disruption.
7326-39
Figure 39. Typical failure Fe and Fe-Ni coating with
electroless Ni bond medium.
52
~7No.
____ -bdt W-41---o.
_______ ~No. 1
.- o
3 2X
~ Figure 40. Results of Tribometer testing of bare finish ground electrol s- Ni.
-72 No 2 .
- No. 2
-~ew - no.- ~. 4;
Magn: 2X
Figure 41. Results of Triborneter testing, of carbonitrided Fe + AFML (DCI-3943).
Table M(LX.
somrna.-Y of tribameter wear Scars.
Cwcdiica Wear scar dceph (in.)
Ejectroless nickel (bare) 0.000290
Elect-oless nickel -AFMIL-41 0.000063
F-Jecroleb- -nickel - Ag-N-bTe-v 0.000110
Electroless -nickel t-Trflon-1MoS7 0.000028
Carbonit-ridei iroei fbare) 0-.000048
Carbonitrided ironI Ag-N\bTe,, 0.000026
Carbon-itrided L-on AFAML-41 0.000013
Carbonifridc-d iron-nickel (baz-e) 0.000026
Carbowntrided iron-nickel Ag-MoTeg 0. 000077
Carbor-itridedi iron-nickel AFNIL-41 0. 0000 Is
Static coefficient of friction
- %0 Zý 0% hi _J 00
Electroless nickel (bare)
Electroless nickei + AFML -41
Electroless nickel + Ag-Ntire
Electroless nickel + Teflon-MoS2
Carbonitrided iron (bare) ý U ý UHCarbonitrided iron + Ag-NbTe2
Carbonitrided iron + AFML -41Carbonitrided iron-nickel (bare'?nhiuuinlsinCarbonitrided iron-nickel + Ag-NbTe2 niinlniCarbonitrided iron-nickel + AFML-41
Be-,i n n jg of testAfter 1000 cycles lllll
7326-42
Figure 42. Summary of Tribometer friction testing.
5.5
THREE-BALL-A ND-CONE TESTS
The DDA-designated three-ball-and-cone test facility consists of eight units for the evaluation
of materials under high Hertzian rolling contact fatigue loads. Figure 43 is a view of the
typical test rigs in DDA Materials Laboratories and Figure 14 shows a schematic of the rig
system. The test facility consists essentially of a high speed shaft which holds and drives the
test cone specimen; a bottom fixture which retains the three ball bearings and outer race; a
temperature controllable positive pressure lubricating system; loading piston; and automatic
shut-off controls. The test performed with this facility is comparable to the cyclic compres-
sive or crushing load in gear and bearing usage. Both lubricated and oil-starved testing can
be performed up to 600, 000 psi HIertzian stress levels.
Test Parameters
* Test machine speed, rpm 10, 770
* Stress cycles/hr 1,518,570
0 Test cone surface fiaish, rms 4
* Total system vibration at origin of test, rms volts max 0. 3; optimum 0. 1
* Contact ball permanent set None
* Lubricant temperature, OF 190 to 200
* Lubricant MIL-L-7808
RaceTCC O0i1 return
Test oil Oil supply
Loading piston
7326-43 7326-44Figu..e 43. Three-ball-and-cone test rigs. Figure 44. Three-ball-and-cone fatigue
tester schematic.
56
-- ____ __ ______
Cone Test Specimens, Figure 45 were manufactured with 15 mils of iron-nickel or electroless
nickel plating over Ti 6AI-2Sn-4Zr-6Mo. The specimens were tested bare and with Ag-Nb-
TeO2 and MoS2 -SbO 3 lubricant coatings as follows.
Surface lubricant coating
Plating None Ag-NbTe 2 MoS2 -Sb 2O 3
Iron-nickel
Single temper 8 - -
Double temper 18 8 10
Electroless nickel 14 8 8
Figure 46 shows a finished test specimen together with the bearing balls and outer race used
on the three-ball-and-cone tests.
The following cone fatigue tests shown in Tables XX, XXI, and XXII were run to determine the
endurance limit of the various combination of materials and surface coatings.
Figure 47 is a summary of the cone fatigue tests which show their respective fatigue life values
relative to AMS-6265 carburized steel.
A typical pitting fatigue failure is shown in Figures 48 and 49.
324 (Pol ish)
109.60°0
109.28
O. 500 dia.0. 4%
±0.301. 000 "
Break edges 0. 015 - 0. 030 RScale - 4 x size 7326-45
Figure 45. Th'-ee-ball-and-cone rig test specimens.
57
7326-46
Fgure 46. ThreeoIm1-and-cone test specimens.
:I .I_,-AMS 6,-aruized steel
amE
L)
10N jo g 8 io'• 1010Celes-Hz
7326-41
S~Figure 47. Three-ball-and-cone test summary.
S77326-48
Figure 48. Typical cone specimen failure.
58
Table XX.
Three-ball-and-cone test results--iron-nickel alloy.
Specimen Load level Stress
SNo. Hertizian (psi) cycles Dispositon
Carbonitrided iron-nickel alloy vacuum diffused, single temper-lubricant: none
4 600,000 3.9 X 105 Failed
6 600,000 3.1 X 105 Failed
2 500,000 6.8 X 106 Failed
5 500,000 4.2 X 106 Failed
7 400,000 1.5 X 107 Failed8 400,000 6.9 X 107 *1 300,000 4.0 X 108 Failed
3 300,000 1.0 X 108 **
Carbonitrided iron-nickel alloy vacuum diffused, double temper--lubricant: none
S11 600,000 2.5 X 108 Terminated
13 600,000 1. 1 X 108 Terminated14 600,000 3. 1 X 108 Terminated
17 600,000 8. 7 X 107 Terminated
20 600,000 2.5 X 105 **
21 600,000 2. 6 X 108 Terminated
22 600,000 1.6 X 107 Failed
12 500,000 5. 8 X 108 Terminated
23 500,000 6.9 X 108 Terminated
24 500,000 9.2 X 107 Failed
25 500,000 --- **
26 .500,000 6.8 X 108 Terminated
9 400,000 1.1 X 109 Terminated
10 400,000 1. 1 X 109 Terminated
Carbonitrided iron-nickel alloy vacuum diffused, double temper, peen-lubricant: none15* 600,000 7.7 X 105 Failed
16* 600,000 1.4 X 106 Failed18* 600,000 5. 7 X 106 Failed
r 19* 600,000 1.4 X 107 Failed
*Abnormally high vibration--surface finish: rms 15 to 17.
**Abnormal failures are those which show eccentric wear patterns, fail at test inception,
or experience high initial vibration.
59
Table XX1f.
Three-ball-and-cone teq results-iron-nickel alloy and iron.
Specim'en i Loaq level Stress
No. Hertizian (psi) cycles Dispositon
"Iron-nickel alloy vacuum diffused, double temper-,lubricant: MoS2 -SbO3
3 600,d00 1. 1 x 108 Terminated
4 600,000 i - *
10 600 000 2.3 X107 *
.5 500,C00 2.5 X 10 7 *
6 500,00) 1 7.9 X 108 Terminated
7: 500,000 4.7 X 10 8 Terminated
8 500,000 7.7 )ý 107 Failed
9 500,000 --- .
1 400,000 2.5 X 107 Failed
2 400,000 4.4 X 10 8 Failed
Iron-nickel alloy vacuum diffused, double temper-7lubricant: Ag-Nb-te 2
1 600,000 A.-
2 600,000 ---
3 600,000 --- *
4 60,0 000 1 1.8 x 108 Te. .ninated5" 500,000 2. 1 X 108 Terminated
6 500,000 5.7 X 108 Terminated
7 500,000 6.8 X 10 7 Terminategd
8 500,000 6.8 X10 7 Terminated
*Abnormal failures are those'which show ecdentric wear patterns, fail at test
inception" or experience high initlal vibration.
Oil Starvation Testing
Oil starvation testing attempts to shut-off the lubridant and create an oil starvation failurewere unsuccessful. tResidua.l lubrication was sufficient to allow' test termination (over 1.0 X
* 108 stress cycles) on bare specimens without failure.
Three-Ball-And-Cone Test Conclusions
The followinb Lonclusions have been made concerning the compressive load capabilities of the
systemis based upon three-ball-and-cope testing. Also refei to Tables XX through XXII,
0 The Nichem system has extenpive scatter of results not attributable to test variations and
is inferior to carbonitrided iron-nickel. Further pursuit of the Nichem syptem is not
recotnmended ac this time.
60'__ _ _
Table XXIL
Three-ball-and-cone test results-electroless nickel.
Specimen Load level StressSNo. Hertizian (psi) cyvcles Dispositon
Electroless nickel (Nichem) hardened and aged-lubricant: nonei
1 600,000 1.3 X 104 Failed
2 600,000 1.3 X 104 Failed
11 500,000 7.2 X 105 Failed
12 500,000 6.1 X 108 Failed
14 500,000 3.7 X 105 Failed
5 400,000 4.9 X 105 Failed
6 400,000 2.5 X 108 Failed
9 400,000 5.0 X 107 Failed
10 400,000 9.2 X 107 Failed
3 300,000 1.4 X 106 Failed
4 300,000 1.4X 106 *
7 300,000 4.8 X 104 *
8 300,000 6.1 X 107 Failed13 300,000 7.6 X 108 Terminated
Electroless nickel (Nichem) hardened and aged-lubricant: MoS2 -SbO 3
Si 3 400,000 1.5 X10 6 Failed
S4 400,000 1.1 X 106 Failed
1 300,000 9.0 X 106 Failed
2 300,000 1.2 X 107 Failed
5 300,000 2.1 X 106 Failed
6 300,000 8.7X 108 Failed
7 300,000 4.1 X 108 Failed
8 300,000 4.0 X 106 Failed
Electroless nickel (Nichem) hardened and aged-lubricant: Ag-Nb-Te 2
1 300,000 3.1 X 107 Failed
2 300,000 1.3 X 106 Failedi3 300,000 1.5 X 108 Failed
4 300,000 3.5 X 106 Failed5 300,000 2.8 X 106 Failed6 300,000 3.2 X 106 Failed7 300,000 3.6 X 106 Failed
8 300,000 --- *
*Abnormal failures are those which show eccentric wear patterns, fail at test inception, or
experience high initial vibration. 61
S~7326-49
Figure 49. Typical microsection of pitting fatigue failure.
0 The iron-nickel alloy system appears competitive with cased steel test results.
0 T£est termination to accomplish the greatest quantity of evaluations precludes determina-
tion of the maximum fatigue capabilities for the material. However, the data to depict
minimum values.
0 Double temper of the specimens is a definite improvement and is considered a direct asset
to both bearing and gear life.
0 Lubri•cation coatings do not appear to have any positive influence on three -ball-and- cone
{ test specimens.
!R. R. MOORE TESTS
} Three groups of Re R. Moore test specimens were fabricated of Ti 6A1-2Sn-4Zr-6Mo. One
i group was tested bare after being processed through the thermal treatment that the gears
} would receive. The second group was iron plated and the third group was iron-nickel plated.
S~Both plated groups were processed as shown in Table XXIII.
S~The Re R. Moore specimens as shown in Figure 50 t,,ere tested to establish their fatigue en-
I durance limits. Test results are shown in Table XXIV.
: Both iron and iron-nickel coated titanium show lower fatigue life than bare titanium, with
relative summary shown in Figure 51.
Electron Microscope Analysis
Representative fractures of each group are shown in Figure 52.
62
I
Table XXIIL
Thermal processing of R. R. Moore plated
fatigue test specimens.
Temperature (*F) Time (hr)
Diffusion 1600 3
Slow cool
Carbonitride 1600 6
Quench Oil
Temper 350 1
-100 1
350 1
500 12
7326-50
Figure 50. R. R. Moore test specimen.
00 B tita nium90 - .
80
Ce7-j I 5 Iron-plated titanium
603
.Iron-nckel-plated titanium
0105 106 107 108
Cycles-Hz 7326-51 7326-51
Figure 51. RI =R. Moore fatigue test summary.
63
Table XXIV.
Results of R.R. Moore fatigue tests.
Condition Stress (-ksi) Cycles X 10 6 Results
Bare Ti 100 0.046 Failed
100 0.043 Failed
90 6.587 Failed
75 33.827 Tervinated
75 18. 519 Terminated
50 14.677 Terminated50 13. 135 Terminated
90 0. 125 Failed
90 9.022 Failed
Fe plated 100 Failed on load
50 4.646 Failed on load
50 0. 075 Failed on load
50 0. 030 Failed on load
45 4. 3E4 Failed on load
45 ,. 960 Failed on load
40 59.037 Failed on load
FeNi plated 60 0.057 Failed
55 1.061 Faileu50 7. 84t6 Failed
50 2. 945 Failed
50 2.848 Failed
40 63. 578 Terminated
40 37.2.76 Terminated
7326-52
Iron Iron-Nickel Bare Titanium
Figure 52. R. R. Moore test specimens.
64
Fractographic studies were made of both the iron and iron-nickel plated titanium specimens
show the following results.
0 No striations typical of fatigue were present in either the Fe or Fe-Ni coating areas.
Fatigue appears to initiate in the titanium at the interface below the coating.
0 * While the iron or iron-nickel coating appears to have failed in a simple overload at the
beginning of the test, the subsurface titanium then progressed for a period in fatigue
originating at or just below the diffusion zone.
R. R. Moore Test Conclusions
0 Both iron and iron-nickel have lower fatigue capabilities than bare titanium.
0 Fractographic studies indicate that fatigue appears to initiate in the titanium at the inter-
Lfce below the coating.
CRUSHING TESTS
Crushing tests were performed to determine the effect of 2 mils of up-hardened iron at the iron-
titaiium interface.
A block of Ti 6A1-2Sn-4Zr-6Mo was constructed and iron plated to a finish ground depth of
approxima.ely 0. 015 inch.. This surface was given a 2 hr carbonitride.
Subsequent load tests revealed the following:
Load, ksi Deformation
300 Yes275 Yes
250 Yes
225 Yes
200 Marginal
155 None
Subsequent examination revealed no indication of subsurface cracking in the areas of plasticdeformation.
Crushing Test Conclusions
* Static Hertz crushing stress up to 200 ksi will not produce visual deformation of an iron
plated surface of Rc 55 nrin hardness.
* Static Hertz crushing stress above 200 ksi produces permanent set of an iron plated sur-
face of Rc 55 min hardness but will not cause subsurface cracking.
65
RYDER GEAR
Small-scale titanium gears submitted for Ryder Gear Machine testing during this program
"were grouped into three phases:
Phase I Gear material: Ti 6A1-2Sn-4Zr-6Mo
36 teeth, 10. 29 pitch
Hard coated with iron-nickel alloy
Lubricant coated with AFML-41 (MoS2-SbO 3 )
Phase R Gear material: Ti 6AI-2Sn-4Zr-6Mo
21 teeth, 6.0 pitch
Hard coated with iron
Lubricant coated with AFML-41
Phase III Gear material: Ti 6A1-2Sn-4Zr-6Mo
21 teeth, 6.0 pitch
Hard coated with iron
Two sets lubricant coated with AFML-41
One set black oxide surface treated
Typical Phase I and Phase 1/III gear sets, before lubricant coating, are shown in Figures 53
and 54.
7326-53
Figure 53. Phase I type gear: 36 teeth, hard coated with Fe-Ni alloy.
66
ii
I
T326-54
Figure 54. Phase 11/MI type gear: 21 teeth, hard coated with Fe.
Dynamic testing of the small-scale gears was conducted on a Ryder Gear Tester modified by
DDA and consisted of the following major components:
* Ryder-ERDCO Universal Drive Stand and Control Console
* ERDCO Antifriction Ryder Gear Head, Model R-5589
0 ERDCO-CRC Test Oil Cart, Model 2300S-2
* Moore "Nullmatic" Load Control System
The modified Ryder Gear Tester is capzble of performance testing a wide variety of gear ma-
terials and designs, heat-treatment techniques, bonded coating materials, and coated and
liquid lubricants.
Conditions simulating ful]-scale gear tooth crushing loads and tooth bending stresses can be
readily applied and accurately maintained at temperatures up to 300°F. Equipment features
are shown in Figure 55.
67
7326-55
Figure 55,, Ryder-ERDCO gear tester with antifriction gear head and CRC oil cart.
Test Parameters
The following test parameters were maintained throughout the test program as specified:
0 Test gear speed, rpm 14, 000 ±50
e Test oil specification MIL-L-7808G
• Test oil flow rate, ml/min 1, 300 ±25
* Test oil in temperature, OF 135 ±5
0 Test oil system capacity, gal 2
• Test oil filter, microns 10
0 Test gear load, psig As shown ±0. 25
"4Increased to 1, 600 ±25 during last three tests of Phase III gears.
Test Gear Load Schedules
The small-scale gear teeth scuffing and pitting fatigue limits were determined under conditicns
simulating full-scale gear teeth crushing loads and bending stresses. The Phase I gears were
36 teeth, and the Phase II/III gears were 21 teeth gears. The differences between the two gear
designs necessitated two separate load schedules, and these are compared in Table XXV.
68
Table XXV.
Load schedules for small-scale titanium gears tested in Phases I and 11/11L
Normal tooth load Surface stress at pitch
Test time (hr) Torque (IbIin.) (M) line (psi Hz)**
Phase I 11/111 I 11/I I 11,/1 1 11/111
10.0 2.0 470.3 176.2 296.5 111.1 105,930 79,430
10.0 2.0 530.9 239.9 334.7 151.2 112,550 92,650
10.0 2.0 595.2 313.3 375.3 197.5 119,170 105,910
20.0 2.0 663.2 396.6 418.1 250.0 125,790 119,150
20.0 2. 0 734. 9 489.9 463.3 308.7 132, 410 132, 380
20.0 10.0 810.2 592.4 510.8 373.5 139,030 145,640
20.0 10.0 889. 2 705.1 560. 6 444. 5 145, 650 158, 870
20.0 10.0 971.9 827.5 612.8 521.7 152,270 172,000
20. 0 10. 0 1, 058. 2 959.7 667.2 605. 1 158, 890 185, 370
*Phase I is a 36-tooth load schedule.
Phase Ul/III is a 21-tooth load schedule.**Based upon Young's Modulus: 30. 0 X 106
Test Gear Inspection
The narrow test gear teeth were inspected under magnification upon the completion of each
timeiload increment, and after each equipment shut-down, whether scheduled or unscheduled.
Gear teeth were evaluated on the bases of relative rate of tooth face scuffing, pitting fatigue,
compression cracking of the hard coating, loss of hard coating, or other isually observable
distress. Wide test gear teeth were inspected without magnification at thc same time. De-
tailed metallurgical investigations were conducted on the gears only after test termination.
Ryder Gear Test Data
A tabular summary of each gear set installed and tested on the Ryder Gear Tester during this
program, the maximam test time, and the condition of the gears at test termination is pre-
sented in Table XXVI. Detailed data recorded at each inspection of the gears will be found in
Appendix III.
Metallurgy Analysis
Phase I Analysis
Test I. 1-Tooth fracture of wide gear shown in Figure 56 progressed from surface blemish.
Narrow gear showed only minor tooth scuffing.
69
Table XXVL
Summary of Ryder gear tests conducted on small-scale gears
during Phases I, H, and Ill.
Phase I
Test Gear Gear Total time Maximum
No. set No. width (hr) stress (psi) Gear condition at test termination
I i-A Narrow 30.0 119, 170 No failure, normal scuff wear only
1-B Wide Tooth 35 broken: all others normal scuff wear
2 2-A Narrow 14.0 105, !30 Overtemperature due to lubricatior, loss
2-A Wide Overtemperature due to lubrication loss
3 1-B Narrow 10.0 105,930 Teeth 13-18 broken: others show impact damage
2-B Wide Lmpact damage on numerous teeth
4 3-A Narrow 2.5 86, 100 Mtisalignment: excessive wear on all teeth
3-A Wide Misalignment; excessive wear on all teeth
5 4-A Narrow 17.4 112,550 Tooth 34 broken; plate loss on other tips
4-A Wide Plate loss on tips of numerous teeth
Phase 11
I 2-A Narrow 6.0 105, 910 Misalignment; no observable damage
2-A Wide Misalignment; no observable damage
2 2-B Narrow 12.5 158,870 Plate damage on teeth 6, 7, 12, 15, & 19
2-B Wide Minor scuffing, no observable damage
3 3-A Narrow 12.3 158, 870 Plate loss on all teeth*2-A Wide Plate cracked on all teeth
Phase III
I I-A Narrow 1.0 79, 430 Loose nut permitted misalignment; compression damage
1-A Wide Misalignment:. some compression damage
2 I-B Narrow 0.1 79,4-.0 Loose nut permitted misalignment: compression oamage
1-B Wide Misahigr;'cnt.. plate loss on teeth 10-13
3 2-A Narrow 29.2 158, 870 Tooth 7 plate loss;: plate smeared on other teeth
2-A Wide Plate smeared on numerous teeth
4 3-A Narrow 19.5 145, 640 Gear web fractured:, minor scuffing on all teeth
3-A Wide Minor scuffing on all teeth
5 2-13 Narrow 21.7 158, 870 Tooth 7 broken; scuff damage on all teeth
2-B Wide Minor scuff damage on all teeth
6 4-A Narrow 8.0 119, 150 Tooth 18 plate loss; minor scuffing on all teeth
4-A Wide Minor scuffing on all teeth
Note:, Phase I-Gear sets 1, 2, and 3 coated with iron-nmckel alloy,
Gear set 4 coated with iron only.,
Phases II/I1--All sets ,oated with iron only.
'ýPreviously used in Test 1 for 6. 0 hours under load,
70
L
Test I. 2-Test rig failure causing loss of lubrication caused premature gear failure. No gear•. analysis made.
Test I. 3-Fracture of narrow gear teeth resulted from multiple indications of fatigue failurein the area of high nickel concentration in the tooth root fillet area. Figure 57 shows the frac-tured tooth failures.
-7326-5,6
Figure 56. Wide gear tooth fracture.
7326-57
Figure 57. Fractured gear teeth induced by fatigue failure.
71
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prne 59.. Phase IL.2 gear ktoth damage.
Fracturing of the iron was predominantly along a plane at the irohi to titanium interface see
Figure 61. Microexamination revealed localized areas of diffusion zone cracking in a plane
relatively parallel to the interface., In addition, 'light cracking of the iron plate was observed
normal to the gear face.
Test 3-Heavy spelling and loss of case was noted on nearly every tooth of both gears as shown
in Figure 62. Daxmiage is attributed to poor bond of the iron coating.
Phase III Analysis
Test 1 and 2-The gears were installed with low retaining nut torque which resulted in fatiguefailure of the lock washer tab. This allowed the lock nut to back off resulti-g in misalignment
and damage to the gear teeth. The gears were turned over and the same hsembly conditionduplicated. A sifrAlar failure resulted as shown in Figure 63. Gear tooth dimage is shown in
Figure 64.
Test 3-Damage to the gears is shown in Figure 65. Photomicrograph typifying the narrow
gear case structure is shown in Figure 66. Microexamivation subsequent to test showed a
plating line defect which led into the diffusion zone and provided a weak junction at Vhich failure
occurr'd.
.I
T26-e1
Fr=e 61- CEc~z 60=5imair r4e -jacd~r
Mgfl: ix7326-62
Figure 62. Phase H1.3 gear teeth damage.
A2- l *uC ,=tbkc
724 A
Figure 64. Phase 1l1. 1 and .2 ;ýear damage by loose retaining nut.
pj
M-3 !ttI
Test 4-Metallurgical examination revealed a fatigue gear we. failure originating in a process-
ing defect and progressing from tht gear tooth root fillet toward the hub, see Figure '37.
7326-66
Figure 66. Phase EEI plating line defect.
M6-67
llre 67. Gear web fait=re.
Test 5-Photomicrograph Figure 68 shows satisfactory case condition in areas adjacent to the
tooth fracture.
Tooth failure of the narrow gear is shown in Figure 69. Fractographic analysis indicated noevidence of fatigue. The extremely rapid fracture is indicative of an overload such as foreign
material going through mesh of the teeth.
P-26-08
Figure 68. Case condition adjacent to failure.44
2ge - t
7326-68
Fiue68-aecodto adaettofiue
>t7 * .
/'.4
Test 6-Photomicrographs shown in Figure 70 are typical of the case structure. Surface
spalling or fracturing is along the diffusion interface. Although fracturing is in the diffusion
zone, titanium base metal can be seen breaking away with the iron case. The bond integrity
in the gears is considered excellent.
Gear Test Summary
The common basis selected was i07 cycles 'o evaluate the fatigue strength of the test gears
relative to hardened steel gears. Figure 71 shows the pitting fatigue stress level of the titanium
gears relative to hardened steel gears. DDA experience design criteria for hardened steel
gears is 242, 000 psi with a negative reciprocal slope value of the S/N curve of 12. 08. The
AGIVMA standard 210. 02 allowable contact stress for 107 cycles is 180-225 ksi for Rc55-60 case
hardness for steel gears.
6The initial contract objective was to achieve 150 hr of operation or 126 X 10 stress cycles at
132, 000 psi (based on steel modulus of elasticity or 100, 000 psi based on titanium modulus of'7
elasticity). This stress related to 107 stress cycles by the slope of the stress-cycle curve is
163, 000 psi.
As the program progressed the objective was established at stated loading cycles of different
stress amplitudes starting at 105, 500 psi and progressing up to 158, 000 psi at 150 hr of test
time. The cumulative damage in fatigue based on Miner's rule is 147,300 psi at 150 hr or
181,600 psi at 10' cycles.
73O6-70
F4•re 70.. P•..-omi- typical of the cae structare.
190, 100 psi Phase II, Ill equivalent objective181,600 psi Phase I equivalent objective
1000 1 163,000 psi equivalent contract objective-f -_ - 152,000 psi Phase III equivalent accomplishment
Steelgear pitting fatigue life- 120,000 psi Phase II equivalent accomplishment
St.147, 300 psi Phase I objectiveS100 --- * - __ 132, 000 psi contract objective
- f 169, 000 psi Phase'l i,'l objective
__Phase I testscheduleSX --- \Phase I I test scheduleý
_ _ '143,000 psi Phase III accomplishment__ 120,200 psi Phase I I accomplishment
94,800 psi Phase I accomplishment96,000 psi Phase I equivalent accomplishment
1 1 1 1 I 11 1 1 1 1 1 1111006 107 108 109
Number stress cycles 7326-71
Figure 71. S/N test schedule.
Phase II and III objective was also a step loading with the stress amplitude starting at 79, 500psi and progressing up to 185, 000 psi at 50 hr of test time. The cumulative fatigue damage at50 hr is 169, 000 psi or 190, 100 psi at 107 cycles.
The average cumulative life of Phase I test results is 94, 800 psi at 12. 07 X 106 cycles or96, 000 psi at 107 cycles for Phase I.
Phase II average cumulative life is 120, 200 psi at 9. 9 X 106 cycles or 120, 000 psi at 107 cycles.
Phase HI average cumulative lif, is 143, 000 psi at 1.9. 9 x 10 cycles or 152, 000 psi at 107cycles.
The equivalent stress levels compared at 107 cycles are:
242,000 psi DDA experience
180. (*0-225. 009 psi AG!(;A allkoable
1"0. 100 psi ?ha.-e 2 dx 11d Il Ct•T!-,e
Vi.
181, 600 psi Phase I objective
163, 000 psi Contract objective
152, 000 psi Phase HI test achievement
120, 000 psi Phase II test achievement
96, 000 psi Phase I test achievement
k ~SECTION VI
CONCLUSIONS AND RECOMMENDATIONS
The coated titanium gears achieved 93% of the initial contract objective or 63% of the fatigue
strength of hardened steel gears. A review of the developed processes for hard coated titanium
gears indicates:
* The plating procedure required excessive attention in the program and will continue to
present a plating challenge due to the problem of obtaining equal plating distribution on the
irregular geometry of the gear teeth
0 The wear surfaces of carbonitrided iron were excellent and appear to be comparable with
hardened steel gears
0 The predomir.nte failure mode of the tested gears was at the interface of the iron and
titanium
o Specimen testing displayed excellent compressive strength properties for iron-coated
titanium
* Model shop fabrication costs for titanium gears was 20le greater than hardened steel gears
It is recommended that further exploration of iron-plated coatings be attempted to develop
added strength and ductility in the diffusion zone by solid solution forming elements at the in-
terface. The relative improveme.' -'-:.,ald oe explored by free-free bending tests followed by
additional Ryder gear manufacture and test.
Since iron-coated titanium three-ball-and-cone tests showed a pitting fatigue strength com -
parable to hardened steel, it is recommended that a program be initiated to adapt this process
to rolling eleaiunt bearing inner and ou,-r races and their rolling elements, titanium shaft
splines, and to the technology of making bearing races integral with titanium shafting by the
iron coating process.
83 $g 4 b1ank)
Appendix I
COMPUTER OUTPUT OF THE DDA GEAR DESIGN PROGRAM
ýXjLLIL Sf'aJF 'W HEt IC I. GEAR OATA-- -
P~iiW,~'±l' ~j'~t ~ 41S AL-) ~ - - ~--)r cC,'rLVT) 07/0)3/67 - -
- (~.4Rl1vIsF'1 c;IO/70 -
C'u'*(P4~týT OATE IS 72/054
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[coo
4I S rL LA EqUS r' A IA S F T1LI V(N
CINTCA LA'Jt k;:Fck4 - pnINr OF T'AN,ENqCY WItq VDLLITE)I TH soC Acc.Crt'IlT ICN CENTER LINE TOOTH RlEFERFqCE -
Y V y y 14TPX0.O 44C'7 1. oaO4,ý b (*)CU91U 1.52257S73 411' Rs MA OR 3.21778?222 O1812 1605
- 0._o)207I 1.6226M'q_ 14A Rl PIN OR -3. 21741395-- o. -6842542 -T.,549051-0.V09., 1. .C )2 SCe. C.CC0750.S) 1.6192ge1 4IN V9 MIN I) ct 3.21659177 0 16q45206 1.59944977 -
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_______99
DEFLECTION SECTION
11G ~* -~ -- ~ ~ *~q~) T~ O.~79O AG- 0.166667 FG= 0.39600d.*qf~ ',i *9~ TNP- n2.2677)C Ap. 0.1'666567_ _FP.G 0.290000
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* 455* *0 0*59 S t080 14 ii95 4SS* S t wo' s ii 4 - .*SSaaae
Nt~ ~ 21.00 RVE'J1a 1.156-0b00 REO". 1.7S0D0066 RA'FCG- 1.51663S6 RS-0OD . -
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V~f -Z[!t. - 1.540jo200 lsR'ýs 1.5,025 - 94Pi IT.S4925
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'TTa-0fVLV Pr*IrrjI C-Nt'-y~ ToiuS, i., aa~n. ACTU-L 0INrI.M 'CCv1.tCT RA0US _____________Tl:F's P C2R.~ECTIC4WIUtA'XE 47; PflTVTTC----------------- V___________
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-;X3-t5 . .s7ZZ12'.6 .21 -ý252s. 1.9076±07a .764cC033 0.0002'7960 03.00391755 C.fed4Wb 6.W 0 r6-6-2 1-4- .5~Z~5 155.5L12.1157C6 94~ 1.6J341455 ?.324C5342 0.003j2a5! 0.00,379677 0.36o'd15ol 6.010~I -v -
I. 07,( 1 32,. '~267L 773I5IZ.B3757533Bc3017 0.356! C.'v60-TG7U~T~6 1T ~f7113 1.z7ocSA_ e. t 3Cr.6 ,*, a.65.70s.3t- 2.9102S255 6.000?1524 0.00061561 0O.,0042&9)-rO-.661Tn7182
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_~1;7525ý1Z) 1.711-i5z,7 '..5117it.E- 3..36_6C0i 2.477O'.6a 30f0057155 0.00031-826 0'. )0 043 574 0.001'32555T1a1761t5, .~A.' S.4--3701., ;.Eql;290*3 i..94463777 0.00070375 -3.01026776 O.u05anZI96 0.aol~R"3A -
i~3~c..7.1r57i T3I7 ~7.9,147a53-. 2.72227S66T ; 0t;324.V4 0OD3DO42461!.e5L5o42 1.cbS.2,5 7..175503C 2.50a~219OO; 2.;4!0!31 0.0004.3225 0.000a23229 0.00042411 0353W
1 ."72117Z!, J.M5"1252 2..AA.~ .35710726s 2.'3-34C5'5 3.00107r1a 0.0032IS;Q 0.0004178S 0.'016A6131
';3- _z .6...,-I- ,.'1376t& 2.22571014 2.7492-,2:5 03.01171"5 0.0)020640 0. -00917 0.00170151- .iOl& i4, 'j2' .793'9 ;0.12054105 ?.714560Z7 3.00135350 0.0001961a 0.03039674 13.001952"63
go0
EQUIVALT LOAD LEVELS FOR S2"1L GEARS-
S±*;,A S:A.E COATED TIT•'•'JIJ- G5AQS - TEST DATA - 'YDEU E = 30.0 C 13•P5
-6 - .30effective, face. width r- .25
TEST RYt-P. HERTZ %TS,-lVIJ ':!PXAL TANCE.ITIAL HP rP! 4 4!A•!TIh.E GAII 51F S TISS *Lit 1 !LB) (I.P.) TPA"EIL
7.n17 400O. ',.,9 28.17 25.!? 9.9?. 1,12.70 C0.00252 iVO00.%...66 45000. 6,. •6 35.66 -. 32.I32 .... I.2°56. -14-Z.b3 .. 0.0031-f! 1,4000.,4. 41) 5fl000. 6.1?. 44.402-- 3 .-.-- 5S- 170-.-C.3? i4000.5..27 55n0n. .4.4q 5:3.;.7 48.'r. -- .18.77 - 213.07 0.004•7, lADO.6.339 0W000 .30n.'. (,'. 39 57.25 22.33 253.57 C.0C56( 2/OC.7.440 65000. 11,1.0n 74.40 .67.43 26.21 297.59 0.00664ý 14000.8a62R 70000. ! ll..85 r6.28 78.2(0 30.40 345. 14 0.00770 1"ocC.o9.3 0 -5 75000. 157. i0 99.05 F90-77 34.90 39".20 0.00(04 ý 140'0,.
- 11.770 0000. 18.7-V, 112.70 102.•4 39.71.- 450.79 C.,UO, -24",00C.12.72? P5000. 1111.7- 127.23 115.?.! 4.011-2 . 50, 8.90 0.01136 1'.00014.263 90000. 226.22 142.63 !29.27 50.25 570.53 0.0127,' ,'W0C.15.392 95000. 252.06 158.92 144.03 55.99 635.69 14.0:19/!n 11000.17.600 100009. 279.20 176.0A9 159.5S - 62.0V 70°.36 C.0!ý572 211COO.19.414 105000. '07.! 1,94..14 175.95-------68.0 776.56 0.C1173- 1A0C0..21 .?307 10000. - 77.O1, 213.07 793-1- . 75.01- -_52.28 - .0L9e0 2/ -CO.23.. 1F.5qIIP,". 141.% 232.,8- . 211.06 82.05 931.52 0.02079 ".4CCO..25.'3,57 120'100. A02.17 253.57 229.CL 89.34 10 14.-.28 0.022%,' V&0O20.2"7.51 A 12,1000°. A' fl.39 275.14 249.36 96.9W.. 1100.57 0.02457 1'40c0.20.750 13"000. 1,' 09 207.59 269.71 104.35 1190.37 C.02- - le 000.32.003 135600. "no.00 320.03 290 .D.b 113.0.7 1283.70 0.ý2365 _7 900.31,. 51, d 4 0n000. ';.7.1.n 345.14 ;..1Z. tO 121.6C . 1380.55 C.030Z0 !4,,01.37"X23 1',5000. ;37.2n 370.23 335.54. 130.44IM 14980.92 0.03326. 1-'00.30.620 15(1000. 62n.1.1 396.20 359.0n 139.5e 1584.82 - 3?5 21 f '.000427. M 6 155000. 470.00) 423.06 3F3.,'2 1'. 05 1692o.23 03777 .0(0°." " 160000. 7!!/,.7 450.79 408.56 158.02 1C03.17 C.!9'C25 i'.00.47.041 165001. 7"3).36 '.79.141 434.3/,(. 16a.9f0 l%7.63 0.11.2111 -14001..50..190 17000. !(7.1V. 503.00 '161.22 179.29 2035.61 C .0 f. " V CP"O.53.n2l 175000. =15.32 539.28 £.-o.75 189'.99 2-157.11 0.&0;, 2,'.57.C -3 ll,r•O0. 0:n...,9 570.53 517.00 201.01 2232..14 0.65e.09 140 P.60.267 11; 3C0. q. .16 602.67 546.221 - 212.33 2410.6,, ,.n55n: 1/.-,,0.6.3. 1110 1s*0000. 1n00.2?, 635.69 576.1? 223.9S 2542.75 e.56T71 ! 1'CC0.66.659 195000. 1'Oi.qo 669. r 5f06 .Ift5 .235.90 267r.34. 0.05978. 0,,.70 . 45,6 2.100000. !! 37. I 7v')4.:36 •3A.37 241,1.16 2,.17. 45 C..,n28e ',oca3-
Ito
C)
:A Ll"tT'-: Tl!?.**I39P rU.,S -TEST flAT! - 5YVE- 2 lc.:;
6- .35effective face widdth - .250
TI^:' -4 q InF~ ST~cSS flnV IL3) UpL r "2 STIMSS F- .25
A..75 2.~ 5"' 2 55 f- 22.OZ 230.1)7 'A:2t'1CC
2-0 i'' ~ 11~4 10'3.12 0:.1L t'.I.57 3279.
7-0 O~~~d'f*~'*~~"~.9 1~.' 69.6! 7SA.35 Nl !,C(C 5828.
2.0 7i4.!...,.. '1Q" 1. 12 2sr.07 '2s.6' 2 ZE~.*1CO' %C223; !1Z.. 7377.
'7"ý"O ac.".V 30r 73 79.ni McX7? !234f..92 I.ft2Th5 1 9107.
100 10'~" 2.41 3 73. 5 33E;.:;( i-.0 12.:G.*.f, M436 i~ix. 019.
170 Li..C . t'.7 "Z."2 156.61 177r..29 c.36 ': 13114.
4F.770 ~ ~ ~ ~ ~ ~ ~ e 12#C.7S.$3.9 43.0 1"S
-I O 1 . -z.Anf)- 27 '2 2i76 47 .P I3..2 Zf:7029591
APPENDIX I1
RYDER GEAR TEST INSPECTION DATA SHEETS
FOR HARD COATED, SMALL-SCALE TITANIUM GEARS.
PHASE I PHASE III
Test No. 1, Gear.Set 1-A/B Test No. 1, Gear Set 1-A
Test No. 2, Gear Set 2-A Test No. 2, Gear Set I-B
Test No. 3, Gear Set 1/2-B Test No. 3, Gear Set 2-A
Test No. 4, Gear Set 3-A Test No. 4, Gear Set 3-A
Test No. 5, Gear Set 4-A Test No. 5, Gear Set 2-B
Test No. 6, Gear Set 4-A
PHASE II
Test No. 1, Gear Set 2-A
Test No. 2, Gear Set 2-B
Test No. 3, Gear Set 312-A
Test Data-Phase I, Test No. 1,
Accumulated Calculated surface
Time cycles stress levels (psi)(hr) (millions) Steel Titanium Condition of gear teeth
Break-in schedule
< 1 0. 14 74,816 56,502 Slight buvrish at and below pitch line
< 1 0.42 74,816 56,502 Relatively unchanged
1 0.84 74,816 56,502 Bonded lubricant confined to bottom 1/3 of most
teeth
2 1.68 81,595 61,640 Unchanged
3 2.52 88,396 66,765 Mlore pronounced wear-in pattern on most teeth
4 3.36 95,220 71,910 Relatively unchanged
5 4. 2n 102,042 77,043 Narrow gear teeth relatively unchanged; plating
bubble or blister on wide gear tooth No. 35 near
center below pitch line
Endurance test
6 5.04 108,829 82, 191 No appreciable change on narrow gear; bubble onwide gear tooth partially healed
9 7.56 108,829 82, 191 Relatively little change in either gear
12 10.08 108,829 82,191 Same
15 12. 60 115,643 87,330 Narrow teeth No. 2 and 34 initiated scuffing be-
low pitch line; approx 1/16-in. area of bubble
spalled out on wide tooth No. 35
93
Test Data--Phase I, Test No. 1, (contd)
Accumulated Calculated surface
Time cycles stress levels (psi)
(hr) .(millions) Steel Titanium Condition of gear teeth
20 16. 80 115,643 87,330 Narrow teeth No. 2 and 34 unchanged; No. 12,
13, 15, and 19 show rust-type stains near frpag
face above pitch line25 21.00 122,400 92,459 Narrow teeth No. 1,2,Z,8, 9,13,14,15,17,19,20,
Z9,33,34, and 36 show slight scoring below pitch
line; No. 12, 13, and 18 show rust-type stain nearfront of tooth above pitch line
30 25.20 122,400 92,459 Narrow teeth No. 2,32,34, 35, and 36 showed 11,
4, 7, 5 and 3% scuffing, respectively; wide tooth
No. 35 chipped through the plate on front face;
see Figure 53. (A detailed view of the wide gear
is shown in Figure 54.)
Test No. I terminated
Test Data-Phase I, Test No. 2,
Accumulated Calculated surface
Time cycles stress levels (psi)
(hr) (millions) Steel Titanium Condition of gear teeth
Break-in schedule
<1 0.14 73,754 55,701 Light burnishing affecting approx 1/2 of teethnear front face and 1/2 near rear face
< 1 0.42 73,754 55,701 No change
1 0.84 73,754 55,701 No change
2 1.68 80,431 60,744 Narrow teeth No. 21,22,23,24,26,27, and 32
show increased wear pattern above pitch line
near rear face; teeth No. 25,28,29,30,31,33,34,
35, and 36 same height near front
3 2.52 87,155 65,822 No change
4 3.36 93,856 70,883 No change
5 4.20 100,557 75,944 Narrow teeth unchanged; wide teeth shAw rust-
type stain near front face of No. 5
Endurance test
14 11.76 107, 276 81,018 Test rig fail'are caused loss of lubrication.
Narrow teeth No. 19, 26, 28, and 29 cracked
Test No. 2 terminated
94
Test Data--Phase I, Test No. 3,
Ac:curnulated Calculated surface
Time cycles stress levels (psi)
h hr) (millions) Steel Titanium Condition of gear teeth
Break-Ln sbedule
'1 0.14 75,675 57, 152 Nearly aU teeth of narrow gear had surface
irregularities near the edge breaks at front and
rear faces; wide gear was unchanged
<1 0.42 75,675 57,152 No change
1 0.84 75,675 57,1152 Rust-type stain appeared on 33 teeth of both gears,primarily near rear face
2 1.68 82, 526 62,326 Initiated scuffing near the roots of narrow teeth
No. 1,4,11,16,20,24,27,29, and 31, wide gear
satisfactory
3 2. 52 89,426 6-,537 Surface irregularities readily visible on narrow
teeth No. 5 through 17 and 32 through 36; wide
gear unchanged
4 3.36 96,301 72,729 Narrow gear relatively unchanged, scoring is
negligible; wide gear unchanged
5 4. 20 103, 177 77,922 Narrow teeth No. 5 and 28 showed minor spalling
damage to working surface near front edge break;
surface irregularities on all other teeth except
No. 6 and 33; wid2 gear unchanged. (See Figure
55 for typical gear tooth wear pattern after 4
million cycles.)
Endurance test
10 8.40 110,803 83,681 Fracture of narrow teeth No. 12 through 18; see
Figure 56. (A detailed view of the narrow gear
is shown in Figure 57.)
Test No. 3 terminated
95
Test Data-Phase I, Test No. 4.
S;mall-scale gears
Accumulated Calculated surface
Time cycles stress levels (psi)
(hr) (millions) Steel Titanium Condition of goar teeth
Break-in schedule<1 0. 14 74,137 55,990 Excessive tooth wear indicated
<1 0.42 74, 137 55,990 Increased wear on all teeth
1 0.84 74, 137 55,990 Increased wear on all teeth
2 1.68 80,881 61,084 Increased wear on all teeth
2.5 2.10 87,618 66,171 Approx 507o of teeth showed misaligned tooth wear
pattern
Test No. 4 terminated
Note: The test gears were reground to have 0. 005-in. average coating thickness.
When shotpeened, the coating came off in the nickel-rich areas of the tooth
flanks; the gears were not suitable for retesting.
Test Data-Phase I, Test No. 5,
Accumulated Calculated surface
Time cycles stress levels (psi)
(hr) (millions) S~teel Titanium Condition of gear teeth
Break-in schedule
:10 0. 14 74, 146 55,997 Narrow teeth No. 23 and 27 show nicks at tips;
wide gear unchanged
:30 0.42 74,146 55,997 Narrow teeth 14c. 3• 23, and 27 show nicks at
tips; wide gear unchanged
1 0. 84 74, 146 55,997 Unchanged
2 1.68 80,859 61,067 Narrow tooth No. 32 scored at tip; wide gear un-
changed
3 2.32 87,619 66,172 Narrow tooth No. 27 chipped through plate at OD
for two-thirds face widths from front side; wide
gear unchanged
4 3.36 94,353 71,260 Narrow teeth No. 6, 27, and 36 chipped through
plate at OD one-third, three-fourths, and two-
thirds of face width; wide gear unchanged
5 4.20 101,092 76,348 Narrow teeth No. 8 and 32 chipped through plate
at OD two-thirds and three-fourths of face width;wide gear unchanged
96
f Test Data-Phase 1, Test Na. 5, (contd)
Accumulated Calculated surface
Time cycles stress levels (psi)
(hr) (millions) Steel Titanium Condition of gear teeth
Endurance Test
6 --- 114,583 86,537 Narrow teeth No. 1, 4, 5, 6, 8, 10, 27, 30, 32,
33, 35, and 36 had broken tips through iron plate
at OD; wide gear unchanged7 --- 114,583 86,537 Length and width of tip breakage gradually in-
creasing; wide gear und anged
10 --- 114,583 86,537 Additional broken tips on narrow teeth No. 25 and
34; wide teeth No. 33 and 35 show axial cracks near
tip
11 --- 134,7,93 101,800 Narrow gear shows wear and scoring near root of
j i some teeth; broken tip on tooth No. S513:30 --- 134,793 101,800 Additional broken tips on narrow teeth No. 2, 14,
and 24-also increased scoring and wear; addi-tional broken tips on wide teeth No. 30 and 32
16 --- 134,793 101,800 Axial crack near tip of narrow tooth No. 3, no
other change; wide gear unchanged
17 --- 153,236 115,729 Ad.iional broken tips on narrow teeth No. 3, 11
and 12--also approxc one-third of tooth No. 36
missing; adrizonal broken tips on wide teeth No.1,4,5,28, and 29
17:24 --- 173,228 13-q,827 Complete loss of narrow tooth No. 34 (root fracture),
additional broken tips on teeth No. 9 and 16, scoringranged between 6 and 34%; wide gear relatively un-
changed
Test No. 5 terminated
97
Test. Data-Phase II, Test No. 1,
Accuwgulated
Time cycles Hertz stress (psi)
(hr) (X 106) Steel Titanium Condition of the gear teeth
1 0.14 76, 430 60,000 Slight burnishing below pitch line on most teeth,
wear-in pattern
1 0.84 79,430 60,000 No change
2 1.68 79,430 60,000 Wear-in pattern slightly more pronounced, no
scuffing
4 3.36 92,650 70,000 No change
6 5.04 105,010 80,000 Wear-in pattern irdicatesirome misalignment ofgears; test terminated before any observable
damage to gear teeth
Test Data-Phace II, Test No. 2,
Accumulated
Time cycles Hertz stress (psi)
(hr) (x 106) Steel Titanium Condition of the gear teeth
1 0. 14 79,430 60,000 Slight burnishing below pitch line on most teeth,normal wear-in pattern
1 0.84 79,430 60,000 No change
S1.68 79,430 60,000 Wear-in pattern slightly more pronounced, no
scuffing
4 3.36 92,650 70,000 No change
6 5.04 o$bt 9!0 80,000 Narrow No. 7-19: fretting stains no change in
wear-in pattern
8 6.72 119,155 90,,000 N 8-12, 15-17, 19, 20: fretting stains. Indication
of light scuffing above pitch line on numerous
teeth
10 8.40 132.385 100,000 N 4-20: fretting stains: no increase in scuffing
patterns
Endurance Test
12.5 10.50 145,640 110,000 N 3-19: fretting stains; N 6, 12, 15, 19: axial cracks
above pitch line. N 7: plating missing from tip of
tooth. The test terminated before further damage to
narrow gear. No damage observed on wide gear
98
Test Data-Phase II, Test No. 3,
Accumulated
Time cycles Hertz stress (psi)
(hr) (X 106) Steel ritanium Condition of the gear teeth
Break-in schedule
L-1 0.14 79,430 60,000 Narrow No; 1: small pit above pitch line, right
side. Narrow No. 9 - 12, 14, 18: axial cracks
above pitch line. Narrow gear 14, 18: fretting
1stains
1 0.84 79,430 60,000 N 1: no change• N 4-14, 18: axial cracks N3, 11, 12, 14, 15;
fretting stains
2 1.68 79,430 60,000 N 1: no change
N 4-14: axial cracksN 1-21: fretting stains
, IN 11-15, 18, 19: contact in root area
4. 3.36 92,650 70,000 NI: no change
N 4-14, 17, 18: axial cracksN 3-7, 11, 13: fretting strains
6 5.04 105,910 80,000 N 1: no change
N 4-14: axial cracks
N 1-14, 21. fretting stains
8 6.72 119,155 90,000 N 1: no change
N 4: small chip of plate missing from right margin
above pitch line
N 4-14: axial cracksN 1-14, 21: fretting stains
10 8.40 132,385 100,000 N 1: no change
N 4: no change
N 4-14: axial cracks
N 1-14, 21: fretting stains
Endurance
12.3 .0.33 145, 640 110,000 Test terminated because of loss of plating
from all narrow and wide teeth
99
Test Data-Phase I1l, Test No. 1,
Accu=mdated Calculated surface
Time cycles stress levels (psi-)
(b4r (X( 106) Steel Titanium Condition of yesteeth
1 0-. 14 79,430 60,000 Some burn-ishing beow PD
1 . 84 79,430 60.000 Test gear wandered on drive shaft after the zero-
torque drive shaft nut backed of. Plaingon ge2r
teeth appears to be distressed, but not con-
sidered to be sz-fing damage
Tet No.. 1 T-,rnaed
Test Data-Phase III, Test No. 2,
A.ccumulaed Calculated surface
Time ccles' st-ress levels (psi)
(E.r) (X 106) Steel Titanium Condition of oear teeth
<1 0.14 79,430 60.000 Plate cr.,.cked on four teeth after the zero-'orque
drive shaft nut again backed off
Test No. 2 Terminated
Test Data-Phase III, Test No. 3,
Accumulated Calculated surface
Time cycles stress levels (psi)
(hr) (X 106% Steel Titanium Condition of gear teeth
C1 0. 14 79,430 60,000 Light burnishing below PD
<1 0.28 79,430 60,000 No change
<1 0.42 79,430 60,000 No chan-re1 0.84 79,430 60,000 No change
2 1.68 79,430 60,000 No change4 3.36 92,650 70,000 No change
6 5. C4 105,910 80,000 No ceange
8 6.72 119,155 90,000 N-- change10. 0 8.40 132,385 100,000 Teeth 8-13 show initial scuffing (0. 6%)
12. 5 10. 50 145,640 110,000 Significant scuffing all teeth; heaviest on 5, 7-12,21 (21%). Test oil flow increased to 1600 ml/min.,
auxiliary oil cooler installed
13.7 11.51 145,640 110,000 Minor scuffing increese to .23%"
100
Test Data-Phase III, Test No. 3
Accumulated Calculated surface
Time cycles stress levels (psi)
(hr) (X 10-) Steel Titari-am Condition 6 fe_- teeth
15,0 12.60 145,640 119,.000 &Minor scuIng increase to 252.
17-5 14.70 145,640 110,000 No cbange
20.0 16.80 145,640 i10I.00 Sc-- increase to 20j
21-2 17.81 153,875 120,000 Scuffing increase to 33%
22.5 18.90 158,875 120,600 No change
23-5 19.74 158,875 120,000 No cbange
25.0 21.00 158,875 120,000 Moderate increase in scuffing (36%)27. 5 23.10 158,875 120,000 Cracked plating on tooth No. 7. Moderate in-
crease in scuffing of other teeth (40%)
Test s _spended briefly, and then-restarted after nondestructive metallurgical
examination.
27.7 23.27 158,875 120, 000 Cracked plating on tooth No. 7 shows burnishing.
No increase in average scuffing rate (40%)
29.2 24.53 158,875 120,000 Cracked platin: on tooth No. 7 separated along
left edge. Face of mating tooth on driven gear
shows heavy damage, and adjacent teeth show
extensive scuffing. Average scuffing of teeth on
test gear shows sudden increase (75Q)
Test No. 3 Terir inated
Test Data-Phase III, Test No. 4
Accumulated Calculated surface
Time cycles stress levels (psi)
(hr) (X 106 Steel Titanium Condition of gear teeth
<1 0.14 79,430 60,000 Gear teeth were honed prior to lube coating.
Average scuffing was 51 after initial run.
<1 0.42 79,430 60,000 No change
1 0.84 79,430 60,000 No change
2 1.68 79,430 60,000 No change
4 3.36 92,650 70,000 No change
6 5.04 105,910 80,000 No change
8 6.72 119,155 90,000 Average scuffing was 6%
10 8.40 132,.385 100,000 No change
101
Test Data-Phase M1., Test No.. 4. (coatc)
Accunuled CalcuEaed surace
Time cycles stress levels (psi)
(hr) (;K IA~ Steel Titauium Conditiomnof gear teeth
15 12.60 145,640 110,000 No ha•ge
19.5 16.38 14,5.640 110,000 Testin wa• eerted when the tea
indiated a su!ena c~mage in the gear, overaffo-L
Visual etazriiationi revealed that the test gear
bad f.-actured from the root radius between teeth
No. 6 & 7 to the root radius of"a spWine at !he gear
hub -
Test No. 4 Terminated'
I
Test Data-Phase II, Tes. No., 5
Accumulated Calcullted-surface.
Time cycles stress levels (psi)
(hr) (x I0O) Steel Titanium Conditiori of gear teeth
<1 0. 14 79,430 60,000 Gear teeth wvere honed prior to lube coating.
Average scuffing after initial run was
<1 0.42 79,430 60,000 No change
1 0.84 79j430 60,000 No change
2 1.68 79,436 60,000 Average scuffing was 4%
4 3.36 92,650 70,000 No change
6 5.04 105,-910 .80,000 No change
8 6.72 119,155. 90,000 No change
10 8.40 132,385 100,000 Average scuffing was 5%
12.5 10. 50 145,640 110,000 Average scuffing increase to 91
20.0 16.80 145,640 110,000 Average scuffing was 11%o
21.7 18.19 i58,875 120,000 Testing was interrupted when the instrumentatiohi
indicated a sudden change in gear operation. Visualexamination revealed that test gear tooth No. 7 had
fractutred from the gear. The broken tooth did not
appear to be deformed. The average scuff rate on-
the remaining 20 teeth was 17-7
Test No. 5 Terminated
102 ..
LLTest DabL-Phase ME, Testlvo. 6
AccbIaed C*3kmizted S!face
CK (hGS1E) Ree TimmOr ___ ___ Ceimfru= of gear teejm
2 1.L68 79, 430 60,0W0 Awera~ge scuffing mas 34 3-36 -02,650 70.000 No dhappge
-5 5- W- 10 5,09 10 W.000~ Aw-e'rage scufing was 4
- 61219,15 C30,!O 2iui~~z1o e~e htapoi~t25% of the plate on the face of No.. IS tooth was
missfing. The average scuffng of the other
teet-h was stifl 4%
-Test No~. 6 Terminated
4
103 (Page 104 Blank)
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