22-WIS5 Weldability 2006

7/25/2019 22-WIS5 Weldability 2006

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Copyright 2006, TWI LtdWorld Centre for Materials Joining Technology

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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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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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


7/89 Copyright 2006, TWI LtdWorld Centre for Materials Joining Technology

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'



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&



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




,lain Carbon Steels),lain Carbon Steels)o" Carbon Steelo" Carbon Steel 7'7: 7'




.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




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


13/89Copyright 2006, TWI LtdWorld Centre for Materials Joining Technology


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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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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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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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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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



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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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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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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



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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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,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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The Chilling Effect of the *ointThe Chilling Effect of the *oint


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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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.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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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



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Liuid !ron "u#$ide

&i#'

"o#idi&ication

crac

Contractiona# train

Q



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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


.4.4 .4.4

Intergranular li-ui# filmIntergranular li-ui# film

ColumnarColumnargrainsgrains ColumnarColumnargrainsgrains



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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




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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




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,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



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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



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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



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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



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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!



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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



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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/



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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




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Critical areaCritical area

CriticalCritical

areaarea

Critical areaCritical area




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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!




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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




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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




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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


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



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igh contractional

strains

amellar tear

Restraint

Text ,age Ref 22)=




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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



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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


Crac'sCrac's


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Crac'sCrac's

Wel# DecayWel# Decay

Inter-+ran$lar CorrosionInter-+ran$lar Corrosion


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.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



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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'



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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



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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



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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



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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"

Documents

22-WIS5 Weldability 2006