22-wis5 weldability 2006
TRANSCRIPT
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CSWIP 3.1 Welding InspectionCSWIP 3.1 Welding Inspection
TWI Training & ExaminationTWI Training & ExaminationServicesServices
Weldability of SteelsWeldability of Steels
Course Reference WIS 5
Course notes section reference 22
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Weldability of SteelsWeldability of Steels
DefinitionDefinition
It relates to the ability of the metal or alloy! to be "el#e# "ithIt relates to the ability of the metal or alloy! to be "el#e# "ith
mechanical soun#ness by most of the common "el#ingmechanical soun#ness by most of the common "el#ing
$rocesses% an# the resulting "el#e# oint retain the $ro$erties$rocesses% an# the resulting "el#e# oint retain the $ro$erties
for "hich it has been #esigne#'for "hich it has been #esigne#'
is a function of many inter(relate# factors but these may beis a function of many inter(relate# factors but these may be
summarise# as)summarise# as)
Com$osition of $arent materialCom$osition of $arent material
*oint #esign an# si+e*oint #esign an# si+e
,rocess an# techni-ue,rocess an# techni-ue
.ccess.ccess
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Weldability of SteelsWeldability of Steels
The "el#ability of steel is mainly #e$en#ant on carbon & otherThe "el#ability of steel is mainly #e$en#ant on carbon & otheralloying elements content'alloying elements content'
If a material has limite# "el#ability% "e nee# to ta/e s$ecial measuresIf a material has limite# "el#ability% "e nee# to ta/e s$ecial measuresto ensure the maintenance of the $ro$erties re-uire#to ensure the maintenance of the $ro$erties re-uire#
,oor "el#ability normally results in the occurrence of crac/ing,oor "el#ability normally results in the occurrence of crac/ing
. steel is consi#ere# to have $oor "el#ability "hen). steel is consi#ere# to have $oor "el#ability "hen)
an acce$table oint can only be ma#e by using very narro"an acce$table oint can only be ma#e by using very narro"range of "el#ing con#itionsrange of "el#ing con#itions
great $recautions to avoi# crac/ing are essentialgreat $recautions to avoi# crac/ing are essential (e.g., high pre-(e.g., high pre-heat etc)heat etc)
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The ffect of !lloying on SteelsThe ffect of !lloying on Steels
Elements may be a##e# to steels to $ro#uce the $ro$ertiesElements may be a##e# to steels to $ro#uce the $ro$erties
re-uire# to ma/e it useful for an a$$lication're-uire# to ma/e it useful for an a$$lication'
0ost elements can have many effects on the $ro$erties of0ost elements can have many effects on the $ro$erties ofsteels'steels'
1ther factors "hich affect material $ro$erties are)1ther factors "hich affect material $ro$erties are)
The tem$erature reache# before an# #uring "el#ingThe tem$erature reache# before an# #uring "el#ing
eat in$uteat in$ut
The cooling rate after "el#ing an# or ,WTThe cooling rate after "el#ing an# or ,WT
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Iron 3e!)Iron
3e!)0ain steel constituent' 1n its o"n% is relatively soft%0ain steel constituent' 1n its o"n% is relatively soft%
#uctile% "ith lo" strength'#uctile% "ith lo" strength'
Carbon C!)Carbon
C!)0aor alloying element in steels%0aor alloying element in steels% a strengtheninga strengtheningelement "ith maor influence on .4 har#nesselement "ith maor influence on .4 har#ness' Decreases' Decreases
"el#ability'"el#ability'
ty$ically 6 7'258ty$ically 6 7'258
0anganese 0n!)0a
nganese 0n!)Secon#ary only to carbon for strength% toughnessSecon#ary only to carbon for strength% toughnessan# #uctility% secon#ary #e(oxi#iser an# also reacts "ithan# #uctility% secon#ary #e(oxi#iser an# also reacts "ith
sul$hur to form manganese sul$hi#e'sul$hur to form manganese sul$hi#e'
67'98 is resi#ual from steel #e(oxi#ation 67'98 is resi#ual from steel #e(oxi#ation
u$ to 6:';8 in C(0n steels! im$roves strength & toughnessu$ to 6:';8 in C(0n steels! im$roves strength & toughness
Silicon Si!)Silicon
Si!)Resi#ual element from steel #e(oxi#ation'Resi#ual element from steel #e(oxi#ation'
ty$ically to 67'
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Steel !lloying le"entsSteel !lloying le"ents
,hos$horus ,!),hos
$horus ,!)Resi#ual element from steel(ma/ing minerals'Resi#ual element from steel(ma/ing minerals'
#ifficult to re#uce belo" 6 7'7:58 brittleness#ifficult to re#uce belo" 6 7'7:58 brittleness
Sul$hur S!)Sul
$hur S!)Resi#ual element from steel(ma/ing mineralsResi#ual element from steel(ma/ing minerals
6 7'7:58 in mo#ern steels 6 7'7:58 in mo#ern steels
6 7'77
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Steel !lloying le"entsSteel !lloying le"ents
>ic/el >i!>ic/el>i!))?se# in stainless steels% high resistance to corrosion?se# in stainless steels% high resistance to corrosionfrom aci#s% increases strength an# toughnessfrom aci#s% increases strength an# toughness
0olyb#enum 0o!0olyb#enum 0o!)) .ffects har#enability' Steels containing.ffects har#enability' Steels containingmolyb#enum are less susce$tible to tem$er brittleness thanmolyb#enum are less susce$tible to tem$er brittleness thanother alloy steels'other alloy steels' Increases the high tem$erature tensile an#Increases the high tem$erature tensile an#cree$ strengths of steel' ty$ically 6 7'5 to :'78cree$ strengths of steel' ty$ically 6 7'5 to :'78
>iobium >b!>iobium>b!))a grain refiner% ty$ically6 7'758a grain refiner% ty$ically6 7'758
@ana#ium @!@ana#ium@!))a grain refiner% ty$ically 6 7'758a grain refiner% ty$ically 6 7'758
Titanium Ti!TitaniumTi!))a grain refiner% ty$ically 6 7'758a grain refiner% ty$ically 6 7'758
Co$$er Cu!Co$$er Cu!))$resent as a resi#ual% ty$ically 6 7'
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MaterialsMaterialsIronIron FeFe
CarbonCarbon
CC
is for Strengthis for Strength
ManganeseManganese MnMn is for Toughnessis for Toughness
SiliconSilicon SiSi < 0.3% eo!idiser< 0.3% eo!idiser
"lu#iniu#"lu#iniu# "l"l $rain rener&
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Classification of SteelsClassification of Steels
Steels are classifie# into grou$s as follo"s)Steels are classifie# into grou$s as follo"s)
,lain Carbon Steels,lain Carbon Steels
.lloy Steels.lloy Steels
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Classification of SteelsClassification of Steels
,lain Carbon Steels),lain Carbon Steels)o" Carbon Steelo" Carbon Steel 7'7: 7'
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Classification of SteelsClassification of Steels
.lloy Steels).lloy Steels)o" .lloy Steelso" .lloy SteelsF8 alloying elementsF8 alloying elements
igh .lloy Steelsigh .lloy SteelsGF8 alloying elementsGF8 alloying elements
.lloy Steels are consi#ere# the ty$e of steels that.lloy Steels are consi#ere# the ty$e of steels that
$re#ominantly contain$re#ominantly contain extraextraalloying elements other than Ironalloying elements other than Iron
& Carbon& Carbon
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Classification of SteelsClassification of Steels
Ty$es of Wel#ableTy$es of Wel#able CC%%C(0nC(0n &&o" .lloy Steelso" .lloy Steels
Carbon SteelsCarbon Steels
Carbon contents u$ to about 6 7'258Carbon contents u$ to about 6 7'258
0anganese u$ to 6 7'980anganese u$ to 6 7'98
o" strength an# mo#erate toughnesso" strength an# mo#erate toughness
Carbon(0anganese SteelsCarbon(0anganese Steels
0anganese u$ to 6 :';80anganese u$ to 6 :';8
Carbon steels "ith im$rove# toughness #ue to a##itions ofCarbon steels "ith im$rove# toughness #ue to a##itions of0anganese0anganese
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Classification of SteelsClassification of Steels
Ty$es of Wel#ableTy$es of Wel#able CC%%C(0nC(0n &&o" .lloy Steelso" .lloy Steels
o" .lloy Steelso" .lloy Steels
Strength & toughness raise# even higher by very smallStrength & toughness raise# even higher by very small
a##itions of grain refining elements li/e .luminium%a##itions of grain refining elements li/e .luminium%
>iobium% @ana#ium>iobium% @ana#ium
igher strength gra#es may be referre# to as S. steelsigher strength gra#es may be referre# to as S. steels
igh Strength o" .lloy steels% e'g'% .,I 5 H;5 & higher!igh Strength o" .lloy steels% e'g'% .,I 5 H;5 & higher!
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Classification of SteelsClassification of Steels
Ty$es of Wel#ableTy$es of Wel#able o" .lloy Steelso" .lloy Steels
Steels for Elevate# Tem$erature ServiceSteels for Elevate# Tem$erature Service Chromium Cr! & 0olyb#enum 0o! a##itions give im$rove#Chromium Cr! & 0olyb#enum 0o! a##itions give im$rove#
strength at high tem$erature an# goo# cree$ resistancestrength at high tem$erature an# goo# cree$ resistance Ty$ical steels are)Ty$ical steels are)
2'2582'258Cr :8 0oCr :8 0o =8Cr :80o=8Cr :80o
Steels for o" Tem$erature ServiceSteels for o" Tem$erature Service >i a##itions give goo# toughness at lo" tem$eratures>i a##itions give goo# toughness at lo" tem$eratures
Steels may be referre# to as cryogenic steelsSteels may be referre# to as cryogenic steels Ty$ical exam$les are)Ty$ical exam$les are)
i steel =8>i steels=8>i steels
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Classification of SteelsClassification of Steels
Ty$es ofTy$es of Stainless SteelsStainless Steels
.ustenitic Jra#es.ustenitic Jra#es
.lloye# "ith Chromium & >ic/el.lloye# "ith Chromium & >ic/el
Exam$les ( on(magnetic
o" thermal con#uctivity they Ahol#B the heat #uring "el#ing!o" thermal con#uctivity they Ahol#B the heat #uring "el#ing!
igh ex$ansion coefficient ( more #istortion #uring "el#ingigh ex$ansion coefficient ( more #istortion #uring "el#ing
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Classification of SteelsClassification of SteelsTy$es ofTy$es of Stainless SteelsStainless Steels
3erritic & 0artensitic Jra#es3erritic & 0artensitic Jra#es
.lloye# "ith Chromium but have no or lo" >ic/el content!.lloye# "ith Chromium but have no or lo" >ic/el content!
Exam$les (Exam$les ( :
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Classification of SteelsClassification of Steels
Ty$es ofTy$es of Stainless SteelsStainless Steels
Du$lex Jra#esDu$lex Jra#es
.lloye# "ith Chromium & some >ic/el.lloye# "ith Chromium & some >ic/el
Exam$les (Exam$les ( 228Cr 58>i & 258Cr F8>i228Cr 58>i & 258Cr F8>i
Calle# #u$lex because there are 2 $hases ( 578 ferrite Calle# #u$lex because there are 2 $hases ( 578 ferrite 578 austenite578 austenite
The $resence of ferrite means that the steels can beThe $resence of ferrite means that the steels can bemagnetise#magnetise#
Stronger than
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Stainless SteelStainless Steel
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Carbon e#$i%alent &or"$laCarbon e#$i%alent &or"$la
The "el#ability of the material "ill also be affecte# by the amountThe "el#ability of the material "ill also be affecte# by the amountof alloying elements $resent'of alloying elements $resent'
TheThe Carbon E-uivalentCarbon E-uivalentof a given material also #e$en#s on itsof a given material also #e$en#s on itsalloying elementsalloying elements
The higher theThe higher the CC% higher the susce$tibility to brittleness%% higher the susce$tibility to brittleness%
an# lo"er the "el#abilityan# lo"er the "el#ability
TheThe CCor CE@ is calculate# using the follo"ing formula)or CE@ is calculate# using the follo"ing formula)
CE@CE@K 8C K 8C 0n0n Cr 0o @Cr 0o @ Cu >iCu >i
;; 55 :5:5
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Classification of SteelsClassification of Steels
0il# steel CE 7'!0il# steel CE 7'!
Rea#ily "el#able% $reheat generally not re-uire# if lo"Rea#ily "el#able% $reheat generally not re-uire# if lo"hy#rogen $rocesses or electro#es are use#hy#rogen $rocesses or electro#es are use#
,reheat may be re-uire# "hen "el#ing thic/ section,reheat may be re-uire# "hen "el#ing thic/ sectionmaterial% high restraint an# "ith higher levels of hy#rogenmaterial% high restraint an# "ith higher levels of hy#rogenbeing generate#being generate#
C(0n% me#ium carbon% lo" alloy steels CE 7' to 7'5!C(0n% me#ium carbon% lo" alloy steels CE 7' to 7'5!
Thin sections can be "el#e# "ithout $reheat but thic/erThin sections can be "el#e# "ithout $reheat but thic/ersections "ill re-uire lo" $reheat levels an# lo" hy#rogensections "ill re-uire lo" $reheat levels an# lo" hy#rogen$rocesses or electro#es shoul# be use#$rocesses or electro#es shoul# be use#
igher carbon an# alloye# steels CE G 7'5!igher carbon an# alloye# steels CE G 7'5!
,reheat% lo" hy#rogen $rocesses or electro#es% $ost "el#,reheat% lo" hy#rogen $rocesses or electro#es% $ost "el#heating an# slo" cooling may be re-uire#heating an# slo" cooling may be re-uire#
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Process Crac'sProcess Crac's
y#rogen In#uce#y#rogen In#uce# .4.4Crac/ingCrac/ingCL0n steels!CL0n steels!
y#rogen In#uce#y#rogen In#uce# Wel# 0etalWel# 0etalCrac/ingCrac/ingS. steels!'S. steels!'
Soli#ification or ot Crac/ingSoli#ification or ot Crac/ing.ll steels!.ll steels!
amellar Tearingamellar Tearing.ll steels!.ll steels!
Re(heat Crac/ingRe(heat Crac/ing.ll steels% very susce$tible [email protected] steels% very susce$tible CrL0oL@
steels!steels!
Inter(Crystalline Corrosion or Wel# DecayInter(Crystalline Corrosion or Wel# Decaystainless steels!stainless steels!
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Crac'ingCrac'ing
When consi#ering any ty$e of crac/ing mechanism% threeWhen consi#ering any ty$e of crac/ing mechanism% threeelements must al"ays be $resent)elements must al"ays be $resent)
StressStress
Resi#ual stress is al"ays $resent in a "el#ment%Resi#ual stress is al"ays $resent in a "el#ment%through unbalance# local ex$ansion an# contractionthrough unbalance# local ex$ansion an# contraction
RestraintRestraint
Restraint may be a local restriction% or through $latesRestraint may be a local restriction% or through $latesbeing "el#e# to each otherbeing "el#e# to each other
Susce$tible microstructureSusce$tible microstructure
The microstructure may be ma#e susce$tible toThe microstructure may be ma#e susce$tible tocrac/ing by the $rocess of "el#ingcrac/ing by the $rocess of "el#ing
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Crac'sCrac's
y#rogen In#uce# Col# Crac/ingy#rogen In#uce# Col# Crac/ing
d I d d C ld d I d d C ld
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ydrogen Ind$ced Coldydrogen Ind$ced Cold
Crac'ingCrac'ing.lso /no"n as CC% y#rogen% Toe% ?n#erbea#% Delaye#%.lso /no"n as CC% y#rogen% Toe% ?n#erbea#% Delaye#%
Chevron Crac/ing'Chevron Crac/ing'
1ccurs in)1ccurs in)
Carbon SteelsCarbon Steels
Carbon(0anganeseCarbon(0anganese o"% 0e#ium an# igh .lloy Steels)o"% 0e#ium an# igh .lloy Steels)
0ainly in 3erritic or 0artensitic steels'0ainly in 3erritic or 0artensitic steels'
@ery rarely in Du$lex stainless steels%@ery rarely in Du$lex stainless steels%
>ever in >ic/el or Co$$er alloys'>ever in >ic/el or Co$$er alloys'
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Crac/ ty$e)Crac/ ty$e) y#rogen .4 & Wel# 0etaly#rogen .4 & Wel# 0etal
crac/ingcrac/ing
ocation)ocation) .4 ongitu#inal!.4 ongitu#inal!
Wel# metal Transverse!Wel# metal Transverse!
Steel ty$es)Steel ty$es) .ll har#enable steels.ll har#enable steels
inclu#ing)inclu#ing) S. igh Strength o" .lloy!S. igh Strength o" .lloy!
steelssteels
Muench & Tem$ere# steelsMuench & Tem$ere# steelsT0C, thermal mechanicallyT0C, thermal mechanically
controlle# $rocesse#! steelscontrolle# $rocesse#! steels
Susce$tible 0icrostructure)Susce$tible 0icrostructure) 0artensite0artensite
ydrogen Ind$ced Cold Crac'ingydrogen Ind$ced Cold Crac'ing
d I d d C ld d I d d C ld
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There is a ris/ of hy#rogen crac/ing "hen all of the factorsThere is a ris/ of hy#rogen crac/ing "hen all of the factors
occur together)occur together)
y#rogeny#rogen 0ore than :5mlL:77g of "el# metal0ore than :5mlL:77g of "el# metal
StressStress 0ore than N the yiel# stress0ore than N the yiel# stress
Tem$eratureTem$erature
Oelo"
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ydrogen Ind$ced Coldydrogen Ind$ced Cold
Crac'ingCrac'ing0ay occur)0ay occur)
u$ to F2hrs after com$letionu$ to F2hrs after com$letion
In "el# metal% .4% $arent metal'In "el# metal% .4% $arent metal'
.t "el# toes.t "el# toes
?n#er "el# bea#s?n#er "el# bea#s
.t stress raisers'.t stress raisers'
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y#rogen is the smallest atom /no"ny#rogen is the smallest atom /no"n
y#rogen enters the "el# via the arcy#rogen enters the "el# via the arc
Source of hy#rogen mainly from moisture $ic/(u$ on theSource of hy#rogen mainly from moisture $ic/(u$ on the
electro#es coating% "el#ing fluxes or from the consumableelectro#es coating% "el#ing fluxes or from the consumable
gasgas
22
22
22
2222
0oisture on0oisture onthe electro#ethe electro#eor grease onor grease on
the "irethe "ire
Water va$ourWater va$ourin the air orin the air orin thein the
shiel#ing gasshiel#ing gas
1xi#e or grease on1xi#e or grease onthe $latethe $late
ydrogen Ind$ced Cold Crac'ingydrogen Ind$ced Cold Crac'ing
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Steel in ex$an#e#Steel in ex$an#e#
con#itioncon#itionSteel un#er contractionSteel un#er contraction
.tomic
.tomic
y#rogeny#rogen
!!
.bove
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ydrogen Ind$ced Cold Crac'ingydrogen Ind$ced Cold Crac'ing
Susce$tible 0icrostructure)Susce$tible 0icrostructure)
ar# brittle structure 0.RTE>SITE ,romote# by)ar# brittle structure 0.RTE>SITE ,romote# by)
.!.!igh Carbon Content% Carbon E-uivalent CE!igh Carbon Content% Carbon E-uivalent CE!
eat in$ut PLmm!eat in$ut PLmm!K .m$s x @olts x arc timeK .m$s x @olts x arc time
Run out length x :7Run out length x :7iCu>iCu
; 5 :5; 5 :5O!O!high alloy contenthigh alloy content
C!C!fast cooling rate)fast cooling rate) Ina#e-uate ,re(eatingIna#e-uate ,re(eating
Col# 0aterialCol# 0aterial
Thic/ 0aterialThic/ 0aterial
o" eat In$ut'o" eat In$ut'
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0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 1.2 1.4 1.6
%Carbon
Ductility
ar#nessTensile
Strength
0.83 % Carbon
(Eutectoid)Q
Increasing the carbon content "ill increase the strength% but
"ill also increase greatly the ris/ of formation of 0artensite
ffect of Carbon in the Properties of Ironffect of Carbon in the Properties of Iron
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ydrogen Ind$ced Cold Crac'ingydrogen Ind$ced Cold Crac'ing
Ty$ical locations for Col# Crac/ingTy$ical locations for Col# Crac/ing
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y#rogen in#uce#y#rogen in#uce#
"el# metal crac/ing"el# metal crac/ingy#rogen in#uce#y#rogen in#uce#
.4 crac/ing.4 crac/ing
0icro .lloye# Steel0icro .lloye# Steel Carbon 0anganese SteelCarbon 0anganese Steel
ydrogen Ind$ced Cold Crac'ingydrogen Ind$ced Cold Crac'ing
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ydrogen Ind$ced Cold Crac'ingydrogen Ind$ced Cold Crac'ing
Toe crac/ingToe crac/ing?n#er bea# crac/ing?n#er bea# crac/ing
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ydrogen Scalesydrogen Scales
list of hy#rogen scales from OS E> :7::)$art 2'list of hy#rogen scales from OS E> :7::)$art 2'
y#rogen content relate# to :77 grams of "el# metaly#rogen content relate# to :77 grams of "el# metal
#e$osite#'#e$osite#'
ScaleScale.. igh)igh)GG:5 ml:5 ml
ScaleScaleOO 0e#ium)0e#ium):7 ml ( :5 ml:7 ml ( :5 ml
ScaleScaleCC o")o") 5 ml ( :7 ml5 ml ( :7 ml
ScaleScaleDD @ery lo")@ery lo") < ml ( 5 ml< ml ( 5 ml
ScaleScaleEE ?ltra(lo")?ltra(lo") < ml< ml
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Potential ydrogen e%el ProcessesPotential ydrogen e%el Processes
list of "el#ing $rocesses in or#er of $otential lo"est hy#rogenlist of "el#ing $rocesses in or#er of $otential lo"est hy#rogen
content "ith regar#s to :77g of #e$osite# "el# metal'content "ith regar#s to :77g of #e$osite# "el# metal'
ESWESW < ml < ml
TIJTIJ < ml < ml
0IJ0IJ 5 ml 5 ml
00. Oasic Electro#es!00. Oasic Electro#es! 5 ml 5 ml
S.WS.W :7ml :7ml
3C.W3C.W :5 ml :5 ml
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y#rogeny#rogen
StressStress
Tem$eratureTem$erature
ar#nessar#ness
00. basic electro#es!' 0.J00. basic electro#es!' 0.J
Cleaning "el# $re$ etc'Cleaning "el# $re$ etc'
Design% Oalance# "el#ing'Design% Oalance# "el#ing'
eat to
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ydrogen Cold Crac'ing !%oidanceydrogen Cold Crac'ing !%oidance
Re#uce y#rogen evelRe#uce y#rogen evel
Select lo"er hy#rogen $otential $rocess e'g'Select lo"er hy#rogen $otential $rocess e'g'
O.SIC vs' R?TIEO.SIC vs' R?TIE
0.J vs' 00.0.J vs' 00.
Increase hy#rogen #iffusion "ith increase# $reheatIncrease hy#rogen #iffusion "ith increase# $reheat 0aintain $reheat after "el#ing allo"ing #iffusion from "el#0aintain $reheat after "el#ing allo"ing #iffusion from "el#
Oa/e basic 00. electro#esLS.W fluxes ( manufacturersOa/e basic 00. electro#esLS.W fluxes ( manufacturers
recommen#ationsrecommen#ations
CleanlinessL#ryness of consumables an# "el# $re$arationsCleanlinessL#ryness of consumables an# "el# $re$arations
e'g' rust scale grease cutting flui#se'g' rust scale grease cutting flui#s
?se austenitic or nic/el fillers?se austenitic or nic/el fillers
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ydrogen Ind$ced Cold Crac'ingydrogen Ind$ced Cold Crac'ing
,recautions for controlling hy#rogen crac/ing,recautions for controlling hy#rogen crac/ing
,re heat% removes moisture from the oint $re$arations% an#,re heat% removes moisture from the oint $re$arations% an#slo"s #o"n the cooling rateslo"s #o"n the cooling rate
Ensure oint $re$arations are clean an# free fromEnsure oint $re$arations are clean an# free from
contaminationcontamination
The use of a lo" hy#rogen "el#ing $rocess an# correct arcThe use of a lo" hy#rogen "el#ing $rocess an# correct arclengthlength
Ensure all "el#ing is carrie# out is carrie# out un#erEnsure all "el#ing is carrie# out is carrie# out un#er
controlle# environmental con#itionscontrolle# environmental con#itions
Ensure goo# fit(u$ as to re#uce# stressEnsure goo# fit(u$ as to re#uce# stress
The use of a ,WTThe use of a ,WT
.voi# $oor "el# $rofiles.voi# $oor "el# $rofiles
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eat in$ut Keat in$ut K :'; /*Lmm:'; /*Lmm
.m$s K 277.m$s K 277
@olts K
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eat Inp$teat Inp$t
igh heat in$ut ( slo" coolingigh heat in$ut ( slo" cooling
o" toughness grain gro"th!o" toughness grain gro"th!
Re#uction in yiel# strengthRe#uction in yiel# strength
o" heat in$ut ( fast coolingo" heat in$ut ( fast cooling
Increase# har#nessIncrease# har#ness
y#rogen entra$menty#rogen entra$ment
ac/ of fusionac/ of fusion
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*esid$al Stress*esid$al Stress
Resi#ual stress "ill be increase# by)Resi#ual stress "ill be increase# by)
Increasing $late thic/nessIncreasing $late thic/ness
Restraint (Restraint ( rigi# fixturesrigi# fixtures
"el# volume"el# volume
insert in $lateinsert in $late
0ulti($ass vs' single $ass0ulti($ass vs' single $ass
Small "el# bea#s vs' large "el# bea#sSmall "el# bea#s vs' large "el# bea#s
ydrogen Cold Crac'ingydrogen Cold Crac'ing
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ydrogen Cold Crac'ingydrogen Cold Crac'ing
!%oidance!%oidance
o" to Re#uce Resi#ual Stresso" to Re#uce Resi#ual Stress Ensure goo# fit(u$) ( minimum root ga$ an# misalignmentEnsure goo# fit(u$) ( minimum root ga$ an# misalignment
.voi# restraints) ( ,reset the oin.voi# restraints) ( ,reset the oin
,reheat may hel$) ( to slo" #o"n cooling rate,reheat may hel$) ( to slo" #o"n cooling rate
arge "el# $asses) ( higher #e$osition ratearge "el# $asses) ( higher #e$osition rate
0inimise volume of "el# metal) ( ess resi#ual stress0inimise volume of "el# metal) ( ess resi#ual stress
,WT from $reheat tem$,WT from $reheat tem$
Dress "el# toes at $reheat tem$Dress "el# toes at $reheat tem$
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Co"bined Thic'nessCo"bined Thic'ness
Combine# chilling effect of oint ty$e an#Combine# chilling effect of oint ty$e an#thic/ness'thic/ness'
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Co"bined Thic'nessCo"bined Thic'ness
The Chilling Effect of the *ointThe Chilling Effect of the *oint
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Co"bined Thic'nessCo"bined Thic'ness
The Chilling Effect of the *ointThe Chilling Effect of the *oint
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Pre-heat !pplicationPre-heat !pplication
.$$lication 1f ,reheat.$$lication 1f ,reheat
eat either si#e of ointeat either si#e of oint
0easure tem$ 2mins after heat removal0easure tem$ 2mins after heat removal
.l"ays best to heat com$lete com$onent rather than local.l"ays best to heat com$lete com$onent rather than local
if $ossible to avoi# #istortionif $ossible to avoi# #istortion ,reheat al"ays higher for fillet than butt "el#s #ue to,reheat al"ays higher for fillet than butt "el#s #ue to
#ifferent combine# thic/nesses an# chill effect factors'#ifferent combine# thic/nesses an# chill effect factors'
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Pre-heat !pplicationPre-heat !pplication
3urnace3urnace((heating entire com$onent ( bestheating entire com$onent ( best
Electrical elementsElectrical elements(controllable ,ortable Site use Clean(controllable ,ortable Site use Clean
Com$onent cannot be move#'Com$onent cannot be move#'
Jas burnersJas burners( #irect flame im$ingement ,ossible local( #irect flame im$ingement ,ossible local
overheating ess controllable,ortable 0anualoverheating ess controllable,ortable 0anual
o$eration $ossible Com$onent can be move#'o$eration $ossible Com$onent can be move#'
Ra#iant gas heatersRa#iant gas heaters( ca$able of automatic control >o flame( ca$able of automatic control >o flame
im$ingement >o contact "ith com$onent ,ortable'im$ingement >o contact "ith com$onent ,ortable'
In#uction heatingIn#uction heating( controllable Ra$i# heating mins not( controllable Ra$i# heating mins not
hours! arge $o"er su$$ly Ex$ensive e-ui$menthours! arge $o"er su$$ly Ex$ensive e-ui$ment
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!%oiding ICC!%oiding ICC
0aintain calculate# $reheats% an#0aintain calculate# $reheats% an#
nevernever
allo" the inter($assallo" the inter($ass
tem$erature to go belo" the $re(heat valuetem$erature to go belo" the $re(heat value
?se?se o" y#rogeno" y#rogen$rocesses "ith short arcs & ensure$rocesses "ith short arcs & ensureconsumables are correctly ba/e# & store# as re-uire#consumables are correctly ba/e# & store# as re-uire#
If using a cellulosicIf using a cellulosic E ;7:7E ;7:7for the root run% insert the for the root run% insert the ot $assot $assUUas soon as $ossible' Oefore .4
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Crac'sCrac's
Soli#ification Crac/ingSoli#ification Crac/ing
S lidifi i C 'i
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?sually 1ccurs in Wel# Centerline?sually 1ccurs in Wel# Centerline
Solidification Crac'ingSolidification Crac'ing
S lidifi ti C 'i
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Solidification Crac'ingSolidification Crac'ing
.lso referre# as.lso referre# as ot Crac'ingot Crac'ing
Crac/ ty$e)Crac/ ty$e) Soli#ification crac/ingSoli#ification crac/ing
ocation)ocation) Wel# centreline longitu#inal!Wel# centreline longitu#inal!
Steel ty$es)Steel ty$es) igh sul$hur & $hos$horigh sul$hur & $hos$hor
concentration in steels'concentration in steels'
Susce$tibleSusce$tible0icrostructure)0icrostructure) Columnar grains In #irection ofColumnar grains In #irection of
soli#ificationsoli#ification
S lidifi ti C 'iSolidification Crac'ing
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Solidification Crac'ingSolidification Crac'ing
Sul$hur in the $arent material may #ilute in the "el# metalSul$hur in the $arent material may #ilute in the "el# metal
to form iron sul$hi#es lo" strength% lo" melting $ointto form iron sul$hi#es lo" strength% lo" melting $ointcom$oun#s!com$oun#s!
During "el# metal soli#ification% columnar crystals $ushDuring "el# metal soli#ification% columnar crystals $ush
still li-ui# iron sul$hi#es in front to the last $lace ofstill li-ui# iron sul$hi#es in front to the last $lace of
soli#ification% "el# centerlinesoli#ification% "el# centerline The bon#ing bet"een the grains "hich are themselvesThe bon#ing bet"een the grains "hich are themselves
un#er great stress' may no" be very $oor to maintainun#er great stress' may no" be very $oor to maintain
cohesion an# a crac/ "ill result% "el# centerlinecohesion an# a crac/ "ill result% "el# centerline
S lidifi ti C 'iS lidifi ti C 'i
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3actors for soli#ification crac/ing3actors for soli#ification crac/ing
Columnar grain gro"th "ith im$urities in "el# metalColumnar grain gro"th "ith im$urities in "el# metal
sul$hur% $hos$hor an# carbon!sul$hur% $hos$hor an# carbon!
The amount of stressLrestraintThe amount of stressLrestraint
*oint #esign high #e$th to "i#th ratios*oint #esign high #e$th to "i#th ratios
i-ui# iron sul$hi#es are forme# aroun# soli#ifying grains'i-ui# iron sul$hi#es are forme# aroun# soli#ifying grains'
igh contractional strains are $resentigh contractional strains are $resent
igh #ilution $rocesses are being use#'igh #ilution $rocesses are being use#'
There is a high carbon content in the "el# metalThere is a high carbon content in the "el# metal
0ost commonly occurring in sub(arc "el#e# oints0ost commonly occurring in sub(arc "el#e# oints
Solidification Crac'ingSolidification Crac'ing
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Liuid !ron "u#$ide
&i#'
"o#idi&ication
crac
Contractiona# train
Q
S lidifi ti C 'iS lidifi ti C 'i
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Dee$% narro"er "el# bea#Dee$% narro"er "el# bea#
1n soli#ification the1n soli#ification the
bon#ing bet"een the grainsbon#ing bet"een the grains
may no" be very $oor tomay no" be very $oor tomaintain cohesion an# amaintain cohesion an# a
crac/ may resultcrac/ may result
Shallo"% "i#er "el# bea#Shallo"% "i#er "el# bea#
1n soli#ification the1n soli#ification the
bon#ing bet"een thebon#ing bet"een the
grains may be a#e-uate tograins may be a#e-uate tomaintain cohesion an# amaintain cohesion an# a
crac/ is unli/ely to occurcrac/ is unli/ely to occur
Solidification Crac'ingSolidification Crac'ing
.4.4 .4.4
Intergranular li-ui# filmIntergranular li-ui# film
ColumnarColumnargrainsgrains ColumnarColumnargrainsgrains
S lidifi ti C 'iS lidifi ti C 'i
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Crac/ing li/ely
27mm
5mm
Wi#th K 7'FDe$th
5 K 7'2527
igher #ilution levels
faster cooling
Crac/ing unli/ely
Wi#th K G 7'FDe$th
:5 K 7'F527
:5mm
27mm
o"er #ilution levels
slo"er cooling
De$th to Wi#th RatiosDe$th to Wi#th Ratios
Solidification Crac'ingSolidification Crac'ing
S lidifi ti C 'iS lidifi ti C 'i
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,recautions for controlling soli#ification crac/ing,recautions for controlling soli#ification crac/ing
The first ste$s in eliminating this $roblem "oul# be to chooseThe first ste$s in eliminating this $roblem "oul# be to choose
a lo" #ilution $rocess% an# change the oint #esigna lo" #ilution $rocess% an# change the oint #esign
Jrin# an# seal in any lamination an# avoi# further #ilutionJrin# an# seal in any lamination an# avoi# further #ilution
.## 0anganese to the electro#e to form s$herical 0nLS "hich.## 0anganese to the electro#e to form s$herical 0nLS "hich
form bet"een the grain an# maintain grain cohesionform bet"een the grain an# maintain grain cohesion
.s carbon increases the 0nLS ratio re-uire# increases.s carbon increases the 0nLS ratio re-uire# increases
ex$onentially an# is a maor factor' Carbon content 8 shoul#ex$onentially an# is a maor factor' Carbon content 8 shoul#
be a minimise# by careful control in electro#e an# #ilutionbe a minimise# by careful control in electro#e an# #ilution
imit the heat in$ut% hence lo" contraction% & minimiseimit the heat in$ut% hence lo" contraction% & minimise
restraintrestraint
Solidification Crac'ingSolidification Crac'ing
S lidifi ti C 'iS lidifi ti C 'i
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Solidification Crac'ingSolidification Crac'ing
,recautions for controlling soli#ification crac/ing,recautions for controlling soli#ification crac/ing The use of high manganese an# lo" carbon content fillersThe use of high manganese an# lo" carbon content fillers
0inimise the amount of stress L restraint acting on the oint0inimise the amount of stress L restraint acting on the oint
#uring "el#ing#uring "el#ing
The use of high -uality $arent materials% lo" levels ofThe use of high -uality $arent materials% lo" levels ofim$urities ,hos$hor & sul$hur!im$urities ,hos$hor & sul$hur!
Clean oint $re$arations contaminants oil% grease% $aintsClean oint $re$arations contaminants oil% grease% $aints
an# any other sul$hur containing $ro#uct!an# any other sul$hur containing $ro#uct!
*oint #esign selection #e$th to "i#th ratios*oint #esign selection #e$th to "i#th ratios
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"$erica# *n "u#$ide ba##
&or' bet"eeno#idi&ied
+rainCoeion and tren+t
bet,een +rainre'ain
Contractiona# train
Q.## 0anganese to "el#
metal
Text ,age Ref 22)9
S lidifi ti C 'iS lidifi ti C 'i
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Solidification Crac'ingSolidification Crac'ing
Soli#ification crac/ing in .ustenitic Stainless SteelSoli#ification crac/ing in .ustenitic Stainless Steel
$articularly $rone to soli#ification crac/ing$articularly $rone to soli#ification crac/ing
large grain si+e gives rise to a re#uction in grain boun#arylarge grain si+e gives rise to a re#uction in grain boun#ary
area "ith high concentration of im$uritiesarea "ith high concentration of im$urities
.ustenitic structure very intolerant to contaminants.ustenitic structure very intolerant to contaminantssul$hur% $hos$horous an# other im$urities!'sul$hur% $hos$horous an# other im$urities!'
igh coefficient of thermal ex$ansion Lo" coefficient ofigh coefficient of thermal ex$ansion Lo" coefficient of
thermal con#uctivity% "ith high resultant resi#ual stressthermal con#uctivity% "ith high resultant resi#ual stress
same $recautions against crac/ing as for $lain carbonsame $recautions against crac/ing as for $lain carbon
steels "ith extra em$hasis on thorough cleaning an# highsteels "ith extra em$hasis on thorough cleaning an# high
#ilution controls'#ilution controls'
C 'Crac's
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Crac'sCrac's
amellar Tearingamellar Tearing
ll T ia"ellar Tearing
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Ste$ li/e a$$earanceSte$ li/e a$$earance
Cross sectionCross section
a"ellar Tearinga"ellar Tearing
a"ellar Tearinga"ellar Tearing
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a"ellar Tearinga"ellar Tearing
Crac/ ty$e)Crac/ ty$e)
amellar tearingamellar tearing
ocation)ocation) Oelo" "el# .4Oelo" "el# .4
Steel ty$es)Steel ty$es) igh sul$hur & $hos$horous steelsigh sul$hur & $hos$horous steels
0icrostructure)0icrostructure) amination & Segregationamination & Segregation
a"ellar Tearinga"ellar Tearing
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a"ellar Tearinga"ellar Tearing
ocation)ocation)
,arent metal,arent metal
Steel Ty$e)Steel Ty$e).ny steel ty$e $ossible.ny steel ty$e $ossible
Susce$tible 0icrostructure)Susce$tible 0icrostructure),oor through thic/ness,oor through thic/ness
#uctility#uctility
a"ellar Tearinga"ellar Tearing
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a"ellar Tearinga"ellar Tearing
amellar tearing has a ste$ li/e a$$earance #ue to the soli#amellar tearing has a ste$ li/e a$$earance #ue to the soli#
inclusions in the $arent material e'g' sul$hi#es an#inclusions in the $arent material e'g' sul$hi#es an#silicates! lin/ing u$ un#er the influence of "el#ing stressessilicates! lin/ing u$ un#er the influence of "el#ing stresses
o" #uctile materials in the short transverse #irectiono" #uctile materials in the short transverse #irection
containing high levels of im$urities are very susce$tible tocontaining high levels of im$urities are very susce$tible to
lamellar tearinglamellar tearing
It forms "hen the "el#ing stresses act in the shortIt forms "hen the "el#ing stresses act in the short
transverse #irection of the material through thic/nesstransverse #irection of the material through thic/ness
#irection!#irection!
a"ellar Tearinga"ellar Tearing
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a"ellar Tearinga"ellar Tearing
3actors for lamellar tearing to occur3actors for lamellar tearing to occur
o" -uality $arent materials% high levels of im$uritieso" -uality $arent materials% high levels of im$urities
*oint #esign% #irection of stress*oint #esign% #irection of stress
The amount of stress acting across the oint #uring "el#ingThe amount of stress acting across the oint #uring "el#ing
>ote) very susce$tible oints may form lamellar tearing>ote) very susce$tible oints may form lamellar tearingun#er very lo" levels of stressun#er very lo" levels of stress
a"ellar Tearinga"ellar Tearing
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a"ellar Tearinga"ellar Tearing
1ccurs "hen)1ccurs "hen)
igh contractional strains are through the short transverseigh contractional strains are through the short transverse
#irection' There is a high sulfur content in the base metal'#irection' There is a high sulfur content in the base metal'
There is lo" through thic/ness #uctility in the base metal'There is lo" through thic/ness #uctility in the base metal'
There is high restraint on the "or/There is high restraint on the "or/
a"ellar Tearinga"ellar Tearing
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.ssessment of susce$tibility to amellar
Tearing)
Carry out through thic/ness tensile test
Carry out cruciform "el#e# tensile test
Carry out ?ltra(sonic testing
Carry out $enetrant testing of $late e#ges
Carry out full chemical analysis S
7'758!Q
a"ellar Tearinga"ellar Tearing
a"ellar Tearinga"ellar Tearing
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Critical areaCritical area
CriticalCritical
areaarea
Critical areaCritical area
a"ellar Tearinga"ellar Tearing
a"ellar Tearinga"ellar Tearing
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Susce$tible oint ty$esSusce$tible oint ty$es
Tee fillet "el#Tee fillet "el# Tee butt "el#Tee butt "el#
#ouble(bevel!#ouble(bevel!
Corner butt "el#Corner butt "el#
single(bevel!single(bevel!
a"ellar Tearinga"ellar Tearing
a"ellar Tearinga"ellar Tearing
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0o#ifying a Tee oint to avoi# lamellar tearing0o#ifying a Tee oint to avoi# lamellar tearing
Susce$tibleSusce$tible
Susce$tibleSusce$tible Im$rove#Im$rove#
>on(susce$tible>on(susce$tible
>on(susce$tible>on(susce$tible
Jouge base metalJouge base metalan# fill "ith "el#an# fill "ith "el#metal beforemetal before"el#ing the oint"el#ing the oint
Susce$tibleSusce$tible ess susce$tibleess susce$tible
,rior buttering of the oint,rior buttering of the oint"ith a #uctile layer of "el#"ith a #uctile layer of "el#metal may avoi# lamellarmetal may avoi# lamellartearingtearing
a"ellar Tearinga"ellar Tearing
a"ellar Tearinga"ellar Tearing
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0o#ifying a corner oint to avoi# lamellar tearing0o#ifying a corner oint to avoi# lamellar tearing
Susce$tibleSusce$tible >on(Susce$tible>on(Susce$tible
,rior "el#ing both,rior "el#ing both$lates may be groove#$lates may be groove#to avoi# lamellar tearingto avoi# lamellar tearing
.n o$en corner oint.n o$en corner ointmay be selecte# tomay be selecte# toavoi# lamellar tearingavoi# lamellar tearing
a"ellar Tearinga"ellar Tearing
a"ellar Tearinga"ellar Tearing
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,recautions for controlling lamellar tearing,recautions for controlling lamellar tearing
The use of high -uality $arent materials% lo" levels ofThe use of high -uality $arent materials% lo" levels of
im$uritiesim$urities
The use of buttering runsThe use of buttering runs
. ga$ can be left bet"een the hori+ontal an# vertical. ga$ can be left bet"een the hori+ontal an# vertical
members enabling the contraction movement to ta/e $lacemembers enabling the contraction movement to ta/e $lace
*oint #esign selection*oint #esign selection
0inimise the amount of stress L restraint acting on0inimise the amount of stress L restraint acting on thethe
ointoint
#uring "el#ing#uring "el#ing
y#rogen $recautionsy#rogen $recautions
a"ellar Tearinga"ellar Tearing
Short Tensile (Thro$gh Thic'ness)Short Tensile (Thro$gh Thic'ness)
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The short tensile test or through thic/ness test is aThe short tensile test or through thic/ness test is a
test to #etermine a materials susce$tibility totest to #etermine a materials susce$tibility tolamellar tearinglamellar tearing
3riction Wel#e# Ca$s3riction Wel#e# Ca$s
Short Tensile S$ecimenShort Tensile S$ecimen
ThroughThrough
Thic/nessThic/ness
DuctilityDuctility
Sam$le of ,arent 0aterialSam$le of ,arent 0aterial
The results are given as aThe results are given as a STR.STR.valuevalue
Short Transverse Re#uction in .reaShort Transverse Re#uction in .rea
TestTest
a"ellar Tearinga"ellar Tearing
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igh contractional
strains
amellar tear
Restraint
Text ,age Ref 22)=
a"ellar Tearinga"ellar Tearing
a"ellar Tearinga"ellar Tearing
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0etho#s of avoi#ing amellar Tearing)Q:! .voi# restraintQ
2! ?se controlle# lo" sulfur $late Q
! Change oint #esign Q
5! ?se a forge# T $iece Critical
.$$lications!Q
a"ellar Tearinga e a ea g
a"ellar Tearinga"ellar Tearing
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-edei+n
,e#dQ/rind and in&i## ,it
ducti#e ,e#d 'eta#QContro#
retraintQ
or critica# ,or a
&or+ed $iece 'a be
uedQ3orge# T
,iece
a"ellar Tearinga"ellar Tearing
Crac'sCrac's
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Crac'sCrac's
Wel# DecayWel# Decay
Inter-+ran$lar CorrosionInter-+ran$lar Corrosion
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Inter-+ran$lar CorrosionInter-+ran$lar Corrosion
.lso /no"n as Wel# Decay.lso /no"n as Wel# Decay
ocation) Wel# .4' longitu#inalocation) Wel# .4' longitu#inal
Steel Ty$e) .ustenitic stainless steelsSteel Ty$e) .ustenitic stainless steels
Susce$tible 0icrostructure) Sensitise# .4 grainSusce$tible 0icrostructure) Sensitise# .4 grain
boun#ariesboun#aries
Inter-+ran$lar CorrosionInter-+ran$lar Corrosion
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Inter-+ran$lar CorrosionInter-+ran$lar Corrosion
Wel# Decay%Wel# Decay% Intergranular CorrosionIntergranular Corrosion or /nife line attac/%or /nife line attac/%
may occur in austenitic stainless steelsmay occur in austenitic stainless steels
.t the critical range of ;77(957.t the critical range of ;77(957ooC Chromium carbi#eC Chromium carbi#e
$reci$itation at the grain boun#aries ta/es $lace$reci$itation at the grain boun#aries ta/es $lace
.t this tem$erature range chromium is absorbe# by the.t this tem$erature range chromium is absorbe# by the
carbon at the grain boun#aries% "hich causes a localcarbon at the grain boun#aries% "hich causes a local#e$letion of chromium content in the a#acent areas#e$letion of chromium content in the a#acent areas
The #e$letion of chromium content in the affecte# areasThe #e$letion of chromium content in the affecte# areas
results in lo"ering the materials resistance to corrosionresults in lo"ering the materials resistance to corrosion
attac/% allo"ing rusting to occur'attac/% allo"ing rusting to occur'
Inter-+ran$lar CorrosionInter-+ran$lar Corrosion
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Inter-+ran$lar CorrosionInter +ran$lar Corrosion
Sensitisation range "here $ea/ tem$eratures in the .4Sensitisation range "here $ea/ tem$eratures in the .4reaches about ;77reaches about ;7777C to 957C to 95777CC
Inter-+ran$lar CorrosionInter-+ran$lar Corrosion
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Inter-+ran$lar CorrosionInter +ran$lar Corrosion
When heate# in the range ;77When heate# in the range ;7777CC
to 957to 95777C Chromium Carbi#esC Chromium Carbi#esform at the grain boun#ariesform at the grain boun#aries
Chromium migrates to site ofChromium migrates to site of
gro"ing carbi#egro"ing carbi#e
Inter-+ran$lar CorrosionInter-+ran$lar Corrosion
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Inter +ran$lar CorrosionInter +ran$lar Corrosion
Jrain boun#ary a#acent areas become #e$lete# of chromiumJrain boun#ary a#acent areas become #e$lete# of chromium
an# lose their corrosion resistancean# lose their corrosion resistance
.reas #e$lete# of.reas #e$lete# of
Chromium belo" :2'58Chromium belo" :2'58
Inter-+ran$lar CorrosionInter-+ran$lar Corrosion
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Inter +ran$lar CorrosionInter +ran$lar Corrosion
W C!W C!
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W C!W C!
,recautions against Wel# Decay,recautions against Wel# Decay
?sing lo" carbon gra#e stainless steel e'g'
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M? :'M? :' Oriefly #iscuss the four essential factors for hy#rogen
crac/ing to occur
M? 2'M? 2' State four $recautions to re#uce the chance of
hy#rogen crac/ing
M?
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*eheat Crac'ing*eheat Crac'ing
Reheat or Stress relaxation crac/ingReheat or Stress relaxation crac/ing
1ccurs in the .4 of "el#s in o" alloy steels #uring ,WT or1ccurs in the .4 of "el#s in o" alloy steels #uring ,WT or#uring service at elevate# tem$eratures#uring service at elevate# tem$eratures
3actors contributing for Reheat crac/ing)3actors contributing for Reheat crac/ing)
Susce$tible alloy com$ositionSusce$tible alloy com$osition
Susce$tible microstructureSusce$tible microstructure
igh level of resi#ual strain combine# "ith some #egree of tri(igh level of resi#ual strain combine# "ith some #egree of tri(axialityaxiality
Tem$erature in the strain relaxation cree$! rangeTem$erature in the strain relaxation cree$! range
0ost alloy steels suffer some #egree of embritlement in the0ost alloy steels suffer some #egree of embritlement in the
coarse grain area of the .4 "hen heate# at ;77Ccoarse grain area of the .4 "hen heate# at ;77CThe crac/s are intergranularThe crac/s are intergranular
Iron-Carbon #$ilibri$"Iron-Carbon #$ilibri$"ii
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iagra"iagra"