atlas of formabilitymicrostructures. experimental procedure commercially available ultimet wrought...

AD-A268 352

Atlas of Formability

Ultimet

DTIC.ELECTE

AUG-18984,

NCMA

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1. AGENCY USE ONLY (Leave blank) 2. REPORT DATE 3. REPORT TYPE AND DATES COVEREDMarch 24, 1993 Final, Dec. 28, 1992 - Mar. 24, 1993

4. TITLE AND SUBTITLE S. FUNDING NUMBERS

ATLAS OF FORMABILITY C-N00140-88-C-RC21Ultimet Alloy

6. AUTHOR(S)

7. PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES) 8. PERFORMING ORGANIZATIONREPORT NUMBER

National Center for Excellence in Metalworking Technology (NCEMT)1450 Scalp AvenueJohnstown, PA 15904

9. SPONSORING /MONITORING AGENCY NAME(S) AND ADDRESS(ES) 10. SPONSORING / MONITORINGAGENCY REPORT NUMBER

Naval Industrial Resources Support ActivityBuilding 75-2, Naval BasePhiladelphia, PA 19112-5078

11. SUPPLEMENTARY NOTES

12a. DISTRIBUTION /AVAILABILITY STATEMENT 12b. DISTRIBUTION CODE

13. ABSTRACT (Maximum 200 words)

In this investigation, flow behavior of Ultimet alloy was studied by conducting compression tests over awide range of temperatures (950-1200 C) and strain rates (0.001-20 s-1 ). The true stress-true strain flowcurves are presented for each test condition. Constitutive relations were determined from the flowbehavior, and a dynamic material modeling was performed on this material. Thus, the optimumprocessing condition in terms of temperature and strain rate was identified as 1012 C and 0.001 s-1 forthis alloy. Workability of the material as a function of strain rate and temperature was also determined.Microstructural changes during high temperature deformation were characterized, and selectivemicrographs are presented together with corresponding flow curves. Dynamic recrystallization andgrain growth occurred during high temperature deformation in some test conditions. This reportsupplies ample mechanical and microstructural data on Ultimet alloy for engineers in the field ofmetalworking process design.

14. SUBJECT TERMS .15. NUMBER OF PAGES

Ultimet Alloy, Deformation Processing, High Temperature Deformation, (4Processing Map, Metalworking, Deformed Microstructure 16. PRICE CODE

17. SECURITY CLASSIFICATION 18. SECURITY CLASSIFICATION 119. SECURITY CLASSIFICATION 20. LIMITATION OF ABSTRAS

OF REPORT OF THIS PAGE OF ABSTRACT

Unclassified Unclassified Unclassified__________NSN 7540-01-280-5500 " Standard Form "98 (Rev 2-89

NSN 7540i-0 ld t' S

ATLAS OF FORMABEIITY

ULTIMET

by

National Center for Excellence in Metalworking Technology1450 Scalp Avenue

Johnstown, PA 15904

for

Naval Industrial Resource Support ActivityBuilding 75-2, Naval Base

Philadelphia, PA 19112-5078

March 24, 1993

This work was conducted by the National Center for Excellence in MetalworkingTechnology (NCEMT), operated by Concurrent Technologies Corporation (CTC), undercontract to the U.S. Navy as part of the U.S. Navy Manufacturing Technology Program.

The views, opinions, and/or findings contained in this report should not be construed asan official Department of the Navy position, policy, or decision, unless so designated byother documentation.

ATLAS OF FORMABILITY

Process design and modeling engineers typically rely on materials suppliers to providethe data needed to successfully design metalforming processes. However, thisinformation is often not sufficient or appropriate for increasingly sophisticated industrialprocesses and applications. In some cases, there is a total lack of mechanical andmicrostructural data at forming temperatures and speeds. Without proper data, engineersrely on trial-and-error methods of process development and optimization.

The National center for Excellence in Metalworking Technology (NCEMT) has begundeveloping an Atlas of Formability to address this problem. The objective of the Atlas isto provide the mechanical and microstructural data required to develop accurate andrealistic metalforming simulations. These simulations can reduce or eliminate the needfor trial-and-error approaches, thereby streamlining process development andoptimization. To achieve its objective, the NCEMT uses state-of-the-art materials testingand characterization methodologies to develop workability data for advanced alloysystems. This effort is sponsored by the U.S. Navy Manufacturing Technology Program,which selects materials for the Atlas based on priorities set by the Navy. The NCEMTpublishes Atlas Bulletins on a continuing basis.

ULTIMET

ABSTRACT

In this bulletin, flow behavior of Ultimet alloy has been determined by conductingcompression tests over a wide range of temperatures (950-1200 C) and strain rates (10-3-20 s-1). The true stress-true strain flow curves are presented for each test condition.Constitutive relations were determined from the flow behavior, and dynamic materialmodeling was performed. Thus, the optimum processing condition in terms oftemperature and strain rate was identified as 1012 C and 10-3 s-1. Microstructuralchanges during high temperature deformation were also characterized, and selectedmicrographs are presented together with corresponding flow curves. Dynamicrecrystallization and grain growth occurred during high temperature deformation over therange of temperatures tested. This report supplies ample mechanical and microstructuraldata on Ultimet alloy for engineers in the field of metalforming process design.

TABLE OF CONTENTS

Introduction ................................... 1

Experimental Procedure ............................ 1

Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

Summ ary .................................... 64

Implementation of Data Provided by the Atlas of Formability ........ 64

LIST OF TABLES

Table 1. Chemical composition of Ultimet alloy ................. 1

Table 2. List of figures, testing conditions and microstructuralobservations for Ultimet alloy ..................... 2

MTIC QGAx 1s- 4 'F'F'TED 3

Accession ForNTIS GRA&IDTIC TAB 0]Unannounc ed [Justification .-

ST #A, AUTH USNAVIRSA (MR PLONSKY 8/443-6684) A id

PER TELECON, 17 AUG 93 CB ByJ rALA t

Availability CodesAvail and/or

Dist Speocial

Hi

Ultimet

Introduction

Ultimet alloy possesses both the wear-resistant characteristics of cobalt-based Stellite alloysand the corrosion-resistant properties of nickel-based Hastelloy alloys. The alloy also has goodforming and welding characteristics, but work hardening involves mechanical twinning. Theunderstanding of mechanical and microstructural behavior during high temperature deformation is veryimportant in forming this material. In this investigation, flow behavior of Ultimet alloy was studied byconducting compression tests over a wide range of temperatures and strain rates. Constitutiverelations were determined from the flow behavior and subsequently, a dynamic material modeling forthis alloy was performed. Thus, the optimum processing condition in terms of temperature and strainrate was determined. Microstructural changes during high temperature deformation were alsocharacterized to help process design engineers select processing conditions for the desiredmicrostructures.

Experimental Procedure

Commercially available Ultimet wrought bars in annealed condition were used in thisinvestigation. The bars were approximately 19 mm in diameter. The typical microstructure of the as-received material is shown in Figure 1. The chemical composition of the alloy is shown in Table 1.

Table 1. Chemical composition of Ultimet alloy.

Element Co Ni Fe Cr Mo W C N Si Mn B S P

Wt% bal. 8.81 3.22 26.2 5.08 2.47 .07 .092 .37 .69 .002 <.002 <.005

Cylindrical compression test specimens with a diameter of 12.7 mm and a height of 15.9 mmwere machined from the bars. Isothermal compression tests were conducted in vacuum on an MTStesting machine. The test matrix was as follows:

Temperature, C (F): 950 (1742), 1000 (1832), 1050 (1922), 1100 (2012), 1125 (2057), 1150(2102), and 1200 (2192);

Strain rate, s-1: 0.001, 0.01, 0.05, 0.1, 0.5, 1, 5 and 20.

Load and stroke data were acquired during the tests by a computer and later converted totrue stress-true strain curves. Immediately after the compression test, the specimens were quenchedwith forced helium gas in order to retain the deformed microstructure. Longitudinal sections of thespecimens were examined by optical microscopy. The photomicrographs presented are electronicimages and were taken from the center of the longitudinal section of the specimens.

Results

Table 2 is a list of the figures, test conditions, and the observed microstructures. Truestress-true strain flow curves with selected corresponding deformed microstructure are shown fromFigure 2 to Figure 57. True stress vs. strain rate was plotted in log-log scale in Figure 58 at a truestrain of 0.5. The slope of the plot gives the strain rate sensitivity m., which is not constant over theranges of temperatures and strain rates tested. Log stress vs. I/N at the same true strain is shown inFigure 59. A processing map at this strain was developed, Figure 60. The optimum processingcondition is obtained by selecting the temperature and strain rate combination which provides themaximum efficiency in the stable region. This condition is 1012 C and 10-3 s-1 for this material.

I

Table 2. List of figures, testing conditions and microstructural observations for Ultimet alloy.

Figure Temperature Strain Rate Microstructure PageNo C (F) s-I No

Optical MicroscopyAs received Equiaxed grains with an average size of 51.6 pin, 4

large cuboidal-like precipitates (ppt) and extensivetwinning, some inclusions.

2 950 (1742) 0.001 60% dynamically recrystallized (DRX) grains with 5deformed (elongated) original grain boundaries stillvisible, necklacing at large original grainboundaries.

3 950 (1742) 0.01 Same as above, 50% DRX. 64 950 (1742) 0.05 75 950 (1742) 0.1 Same as above. 86 950(1742) 0.5 97 950 (1742) 1 Same as above. 108 950(1742) 5 Same as above. 119 950(1742) 20 60% DRX, the new recrystallized grains have an 12

average size of 5ln, less elongation of the originalgains.

10 1000 (1832) 0.001 95% DRX equiaxed grains with an average size of 13lOwxn, prior deformed grain boundaries are still

, _visible, some ppt. and inclusions.11 1000(1832) 0.01 1412 1000 (1832) 0.05 Same as above, but 90% DRX (prior deformed 15

grains are well defined).13 1000 (1832) 0.1 1614 1000 (1832) 0.5 Same as above. 1715 1000(1832) 1 80% DRX grains with an average size of 8 Wn, prior 18

_ deformed grains are still visible.16 1000 (1832) 5 1917 1000 (1832) 20 Same as above, but -95% DRX. 2018 1050 (1922) 0.001 100% DRX equiaxed grains with an average size of 21

16gm, some grain growth and twinning.19 1050(1922) 0.01 Same as above except smaller grains and some prior 22grain boundaries.20 1050 (1922) 0.05 2321 1050(1922) 0.1 80% DRX equiaxed grains with an average size of 24

_lOjM, deformed prior grain boundaries visible.22 1050 (1922) 0.5 2523 1050(1922) 1 100% DRX equiaxed grains with an average size of 26

lOman in size, some deformed prior grain boundariesvisible.

24 1050 (1922) 5 Same as above, but with some twinning. 2725 1050(1922) 20 Same as above. 2826 1100 (2012) 0.001 100% DRX equiaxed grains with an average size of 29

34pan, extensive twinning.27 1100 (2012) 0.01 3028 1100 (2012) 0.05 Same as above, except that the average grain size is 31

25Mi.29 1100 (2012) 0.1 Same as above, except that the average grain size is 32

21gm.

2

30 1100 (2012) 0.5 Same as above, except that the average grain size is20}M.

31 1100(2012) 1 Same as above, except slightly smaller grains. 3432 1100(2012) 5 3533 1100(2012) 20 Same as above, except that the average grain size is 36

17Mu.

34 1125 (2057) 0.001 100% DRX equiaxed grains with an average grain 37size of 45gM, much twinning.

35 1125 (2057) 0.01 Same as above, except smaller grains. 3836 1125(2057) 0.05 3937 1125 (2057) 0.1 Same as above, except even smaller grains. 4038 1125(2057) 0.5 4139 1125 (2057) 1 Same as above. 4240 1125(2057) 5 Same as above. 4341 1125 (2057) 20 Same as above, except that the grain size is -25ýpm. 4442 1150(2102) 0.001 100% DRX equiaxed grains with an average grain 45

size of 65Fan, extensive twinning.43 1150(2102) 0.01 4644 1150 (2102) 0.05 Same as above, except that the grains are smaller. 4745 1150(2102) 0.1 4846 1150(2102) 0.5 Same as above. 4947 1150(2102) 1 Same as above, but the average grain size is 40pm. 5048 1150(2102) 5 5149 1150(2102) 20 Same as above, except that the average grain size is 52

30±m.50 1200(2192) 0.001 100 % DRX with extensive grain growth, with an 53

average size of 79gm, much twinning.51 1200 (2192) 0.01 Same asabove, except that the grains are smaller. 5452 1200(2192) 0.05 5553 1200 (2192) 0.1 Same as above, except that the average grain size is 56

40pgn.54 1200 (2192) 0.5 5755 1200 (2192) 1 Same as above, but smaller grain size. 5856 1200 (2192) 5 5957 1200 (2192) 20 Same as above, except that the grains are smaller 60

with an average size of 351im.

3

..... 11

..... ......

'Mg

.. ......I

Figure~ ~ ~ ~~~~. 1.. Asrc.e.irsrutr fLlie

K WKS4

300 *

o Ultimet250 .

o_ 20G

¢• 150

• 100I--

50 Temperature: 950 C

Strain Rate: 0.001 s-'

0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8

True Strain

Figure 2. True stress-true strain curve and an optical micrograph from the center of the compressed

sample cut through the compression axis, 950 C and 0.001 s-1.

5

320

'*'240

0 1 1 1

0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8

True Strain


sample cut through the compression axis, 950 C and 0.01 s-1 .

6

500

Ultimet

400

v 3000 2(3

(1) 200

I.-

100 Temperature: 950 0

Strain Rate: 0.05 a-'

0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8

True Strain

Figure 4. True stress-true strain curve, 950 C and 0.05 s- 1.

7

500-Ultimet

0 0

",-" 300Unen

M 2200

I--



0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8

True Strain

Figure 5. True stress-true strain curve and an optical micrograph from the center of the compressedsample cut through the compression axis, 950 C and 0.1 s"1 .

8

600 • , , , *

Ultimet500 .

40

a.Co)U)

if 300

: 200

1 O0 -Temperature: 950 C

Strain Rate: 0.5 8-1

0 ' - 1 ., | . I I I

0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8

True Strain

Figure 6. True stress-true strain curve, 950 C and 0.5 s-1.

9

500

500

400

W 300

2) 200

100 Temperature: 950 CStra In Rate: 1 .0 a-'

0. 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8

True Strain


sample cut through the compression axis, 950 C and I s-1

10

700Ultimet

600

500

C) 400-CO)

-'' 300

L.200


$train Rate: 5.0 a-'

0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8

True Strain


sample cut through the compression axis, 950 C and 5 s-1.

700 *

600

500400

3l 00

~- 200

100 Temperature: 950 C100 Strain Rate: 20.0 e-i

0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8

True Strain

Figure 9. True stress-true strain curve and an optical midcrograph from the center of the compressed

sample cut through the compression axis, 950 C and 20 s-1 .

12

200

Ultimet

160;

120Cl)EL2 1 21

80

4-0 Temperature: 1000 C

Strain Rate: 0.001 e-1

0 I I , I , I , . - .I

0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8

True Strain


sample cut through the compression axis, 1000 C and 0.001 s-.

13

400

Ultimet

'-- 300

¢ 200

Temperature: 1 000 C

Strafn Rate: 0.01 a-'

0 1 1 10.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8

True Strain


14

Ultimet

"-- ~300

CL)

t 200

L..

1-- 100Temperature: 1 000 C

Strain Rate: 0.05 s-i

O0 1 I- -1 1 1

0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8

True Strain

50mFigure 12. True stress-true strain curve and an optical micrograph from the center of the compressed


15

Ult~imet

S300

m 200L.

4-J-

42)

I- 100Temperature: 1000 C


0 - L l . I , I I

0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8

True Strain

Figure 13. True stress-true strain curve, 1000 C and 0. 1 s'l.

16

500Ultimet

400

300

U) 200

100 -Temperature: 1000 CStrain Rate: 0.5 a-'

0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8

True Strain


sample cut through the compression axis, 1000 C and 0. 5 s-.

17

500Ultimet

400

300U')

L.

&o 200

I-


Strain Rate: 1 .0 -'

0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8

True Strain


sample cut through the compression axis, 1O00 C and I s-1 .

18

600Ultimet

500

4 4300

ci)- 300

• 200

1100 Temperature: 1000 CStrain Rate: 5.0 a-'

0 1/ 1 .I .- I- - . I

0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8

True Strain

Figure 16. True stress-true strain curve, 1000 C and 5 s-1.

19

600Ultimet

500

440o_ 4-QQ

S300

ca 200

10 O0 Temperature: 1 000 C


001 .,1 . . I I0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8

True Strain

50.~

Figure 17. True stress-true strain curve and an optical micrograph from the center of the compressedsample cut through the compression axis, 1000 C2 and 20 s-1.

20

200 *

Ultimnet

-'1.50

S 100

50 Temperature: 1 050 C

Strain Rate: 0.001 s-

010.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8

True Strain



21

300 *

-Uti~met250

20

S 1.50

~'1001

50 Temperature: 1050 CStrain Rate: 0.01 a-

0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8True Strain


sample cut through the compression axis, 1050 C and 0.01 s-1

22

300

-Ultime!t

250

n- 200

m• 150

S100


Strain Rate: 0.05 a-'0 0 .1 I • I , I0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8

True Strain


23

300

-Ult.imet

250

a_ 200

cn• 1 50L.

0 100

50 'Temperature: 1050 C


0 1 I I *. I . II

0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8

True Strain


sample cut through the compression axis, 1050 C and 0. 1 s- 1.

24

400-Ultimet

34-0

_ 280-

n 220

160L.

1- 100Temperature: 1050 C

40 Strain Rate: 0.5 a-'

0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8

True Strain


25

Ultimet

400

CL

300CO

(1 200

100 -Temperature: 1 050 C

Strain Rate: 1 .0 9-

0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8

True Strain


sample cut through the compression axis, 1050 C and I s-1

26

500

Ultimet

400

CL

300

U) 200

I--



0 , I , I . I I0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8

True Strain


sample cut through the compression axis, 1050 C and 5 s-1 .

27

500 , , ,-Ultimet

400

300

S200

100- Temperature: 1050 C


0 1 1 1 10.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8

True Strain



28

Ultimet

80

00

60CD

L.



0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8

True Strain

50mFigure 26. True stress-true strain curve and an optical micrograph from the center of the compressed


29

200

Ultimet

1600~

1 20Cl)Cl)

:J3


Strain Rate: 0.01 s-1

0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8

True Strain


30

300U Ultimek

250

a- 200

> 1504-,

U)

:3 100


Strain Rate: 0.05 s-I

0 . I . I I0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8

True Strain

Figure 28. True stress-true strain curve and an optical micrograph from the center of the compressedsample cut through the compression axis, 1100 C and 0.05 s-1.

31

300 *

-Uli~met250-

Q- 200

q~150

S 100

50 Temperature: 11 00 CStrain Rate: 0.1 s-i

0 -1 1 -. I

0 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8

True Strain


sample cut through~ the compression axis, 1 100 C and 0. 1 s-.

32

"400 * .*

Ultimet

"-' ,300

C')Q 200

L.

I- 100Temperature: 11 00 C


0 * - L . I I I ,

0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8True Strain

501Jp



33

400

Ultimet

300

CL

CI) o 2004-

Temperature: 11 00 CStrain Rate: 1 .0 9-1

00.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8

True Strain

0..g

Figure 3 1. True stress-true strain curve and an optical micrograph from the center of the compressedsample cut through the compression axis, T100 C and I s-

34

400 I I I I I i

Ultimet

'- 300

CDU 200I-

-4-.,Co41)

k- 1O00 Temperature: 11 00 C


o0f0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8

True Strain

Figure 32. True stress-true strain curve, 1100 C and 5 s-1.

35

500.Ultimet

400-

300

3,00

.50.

smple~~~~~~~Tepraue cut 00rug Ch opeso xs 0 n 0s

St3nRa6 0. -

100

Ultimet

80

C-%ýý 60-U)

L..

Li) 4o04)



0 I 1 1 .I I I ,

0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8

True Strain



37

200

Ultimet

'-' 150C_

0 50Tempera1ure: 1125 C

Strain Rote: 0,01 a-'

O0 -1 1 1

0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8True Strain

L.L 500•



38

200Ultimet

CL

• 150Temperature: 11 25 C

Strain Rate,. 0.05 a-'H 501

0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8

True Strain


39

300

Ultimet250

nO 200

p 150

4-40

50 Temperature: 1125 CStrain Rate: 0.1 8-i

0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8

True Strain

•501km

Figure 37. True stress-true strain curve and an optical micrograph fr'om the center of the compressedsample cut through the compression axis, 1125 C and 0. 1 s-1.

40

300

Ultimet250

•; 200

a)a,q0 150

L.

S 100I-

,50 Temperature: 1125 CStrain Rate: 0.5 a-'

0 1 -* I - . I

0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8

True Strain


41

Ultimet

S300

CO,

t 200L.

L..- 100


Strain Rate: 1 .0 a-'

0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8

True Strain

5Lm


sample cut through the compression axis, 1125 C and I s-1.

42

4"00

Ultimet

S300

n 200

.- 100Temperature: 1125 C


0 , t I .I * I I . I

0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8

True Strain

501pm


sample cut through the compression axis, 1125 C and 5 s- 1.

43

400Ultirnet

"300

n 200

4)1.~

I- 100Temperature: 11 25 C


0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8

True Strain

Figure 4 1. True stress-true strain curve and an optical micrograph from the center of the compressed

sample cut through the compression axis, 1125 C and 20 s"1.

44

100

Ultimet

80so_

S 60

U)

4.0-

20 Temperature: 11 50 CStrain Rate: 0.001 a-'

0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8

True Strain


sample cut through the compression axds, 1150 C and 0.001 s-.

45

200 * i * ,

Ultimet

160

1 20'J~

80



0 1 -I . - I

0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8

True Strain


46

200Ultime!:

160

"120

L.I--



010.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8

True Strain



47

300 , , • * , ,

Ultimet250

a. 200

CnCn S, 150

4-J

w) 100I--



o0 1 . -I I

0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8

True Strain

Figure 45. True stress-true strain curve, 1150 C and 0.1 s-.

48

300 '

Ultimet250

o_ 200cn

ff 150L.

M 100



0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8

True Strain


sample cut through the compression axis, 1150 C and 0.5 s 1 .

49

300

SUlti met250

a. 200

, 150L.

-I-,/

¢' 100L.


Strain Rate: 1 .0 a-'

00.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8

True Strain


sample cut through the compression axis, 1150 C and I s-1.

50

"400 | i * I * |

Ultimet

" " 300

CD)Co> 200

:3)

-- 100Temperature: 1150 C

Strain Rate: 5.0 s-1

0 1 1 10.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8

True Strain

Figure 48. True stress-true strain curve, 1150 C and 5 s- 1.

51

400Ul+timef

"-'n 300

CI)

(D 200L-

I'- 100Temperature: 11 50 C

Strain Rate: 20.0 s-I

0 , .-I, I - I - . I I I

0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8

True Strain



52

60

Ultimet

,-- 45

ci) 30

L=.

1-- 15Temperature: 1200 C


0 -- I - I I

0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8

True Strain

Figure 50. True stress-true strain curve and an optical micrograph from the center of the compressedsample cut through the compression axis, 1200 C and 0.001 s-1 .

53

80

60

en4.0

L.


Strain Rate: 0.01 e- 1

0 1 A I

0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8

True Strain

5%m

Figure 5 1. True stress-true strain curve and an optical micrograph from the center of the compressed


54

200Ultimet

160 -

r•

1 20CI)a,

L.


Strain Rate: 0.05 e-t

0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8

True Strain


55

200 *

Ultimei

1 60

120UO

41)L..

I-4-



0 * I , I * I I • * I , I ,

0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8

True Strain


sample cut through the compression axis, 1200 C and 0. 1 s'1.

56

300

Ultimet

240 -

180 -Cn

120



0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8

True Strain


57

300

.Ultimet

240

", 1800

S120


Strain Rate: 1 .0 a-'00 : . . I • , • . I I0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8

True Strain


sample cut through the compression axis, 1200 C and I s-1 .

58

4300Ultimet

' 300C_0

Cn 200

I - 100Temperaiure: 1 200 C

Strain Rate: 5.0 a-I

0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8

True Strain



59

400

UItime:

S300

S200

i1)

I.- 1 00

Temperature: 1 200 0

Strain Rate: 20.0 e-'L I I. . - I I

0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8

True Strain


sample cut through the compression axis, 1200 C and 20 s-.

60

10W3

Ultimetx

0 x xx x C

xx"

x A +n 1 ) 2 A2+ Temperature:

-4' A

0 losaco 1100CA 1125C+ 1150CA 1200C

10' 1 0-3 1 0-2 1 0-1 1 00 101

Strain Rate (s-1)

Figure 58. Effect of strain rate on stress in log-log scale at a true strain of 0.5 for Ultimet alloy.

61

103 , ,

Ultimet

CD U AA 1 2 a Strain Rate (s-1)4- A * • 0.001

A •0.01U •0.05

+ 0.5* 1.0

V 5.0o 20.0

101 IL I

0.65 0.68 0.72 0.75 0.78 0.82 0.85

1 /T(1 000/K)

Figure 59. Effect of temperature on stress at a true strain of 0.5 for Ultimet alloy.

62

0.

! -2 0

950 1000 1050 1100 1150 1200

Temperature (C)

Figure 60. Processing map of Ultimet ailoy at a true strain of 0.5.

63

Summary

"Compression tests were performed on a commercially available Ultimet alloy over a widerange of temperatures and strain rates. The experimental conditions in this work were representativeof those in metalforming practice. From the true stress-true strain curves, the flow behavior wascharacterized and a processing map, indicating the optimum processing condition, was generated.This condition is 1012 C and 10-3 s-1 .

The deformed microstructures were characterized from the quenched specimens by opticalmicroscopy and were presented for selected test conditions together with stress-strain curves.

Implementation of Data Provided by the Atlas of Formability

The Atlas of Formability program characterizes the flow behavior of engineering materialsin the temperature and strain rate regime commonly used by metalforming industry. The data arevaluable in design and problem solving in metalforming processes. Microstructural changes duringdeformation are also provided in the Bulletin. This information helps the design engineer to selectprocessing parameters leading to the desired microstructure.

The data can also be used to construct processing maps using the dynamic materialmodeling approach to determine stable and unstable regions in terms of temperature and strain rate.The temperature and strain rate combination at the highest efficiency in the stable region provides theoptimum processing condition. In some metalforming processes, such as forging, the strain rate varieswithin the workpiece. Finite Element Analysis of the process can ensure that strain rates andprocessing temperatures throughout the workpiece fall into the stable regions in the processing map.Furthermore, FEM analysis based on the data from the Atlas of Formability can be coupled withfracture criteria to predict defect formation in metalforming processes.

Concurrent Technologies Corporation uses the Atlas of Formability data to designmetalforming processes, including dynamic material modeling, FEM analysis, and defect prediction.CTC can apply its expertise to develop and optimize metalforming processes. For more information,please contact Dr. Prabir K. Chaudhury, Manager, Forming Department, by calling (814) 269-2594.

64

atlas of formabilitymicrostructures. experimental procedure commercially available ultimet wrought...

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