studi kasus heat treatment pada baja asi

7/25/2019 studi kasus heat treatment pada baja asi

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THE WELDING

OF ALLOYSWITH HIGHERHARDENABILITY:Case Studies

aster Flo Valve Inc (MFV) utilizes many alloys in the construction

requirements of Section IX of the ASME oiler and !ressure VesselCode (herein ASME IX) and A"SI#"ACE M$%&'#IS &&* (herein"ACE) are adhered to+ End,user requirements ty-ically require thatlo.,tem-erature im-act tou/hness testin/ 0e included+ 1he "ACE2standard is invo3ed .hen the end,user service environment is42S,containin/ (sour)+ 1he 0utt .eldin/ of for/ed 5an/es or -i-e(5an/e herein) sections to valve 0odies are e6am-les of ty-icalconstruction methods+ 1he valve 0odies may 0e for/ed or castmaterial de-endin/ on their size and com-le6ity+ 1here are manyalloys availa0le that are suita0le for valve 0ody and 5an/e construction7material used for valve 0odies and 5an/es include AISI 8&9%: AISI;*2% and AS1M A&;2 F&+ In many instances: the valve 0ody materialand the 5an/e metal are dissimilar+ 1his metallur/ical mismatchmayresult in -oor -ro-erties .ithin the .eld metal () + In this case: the en/ineer must consider theheat treated condition: the .elda0ility: the metallur/ical -ro-ertiesand the mechanical -ro-erties of 0oth of the 0ase metals to 0e.elded to ensure that a sound .eldment is -roduced+

&; ?@$"A


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In recent years: end,users have required increased stren/th a

im-act

tou/hness values for .eldments: forcin/ manufacturers to utialternate/rades of materials to meet these demands+ Materials such a8&9%:AISI ;*2% enBoy .ides-read use: ho.ever: im-rovements inmechanical and

corrosion -ro-erties throu/h heat treatment and claddin/ hav0ecomecommon-lace today+ In cases .here these 0ase metals cannoachievethe requisite -ro-erties: it is ty-ical to em-loy material furtheenhancedthrou/h alloyin/+ For these enhanced alloys: the correctcom0inationof .eldin/ -rocess(es): ller metals: -reheat and inter-asstem-erature:heat in-ut: coolin/ rate and !


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1he most common heat treatment cycle for 0oth of these met

an

austenitizin/ -rocess (.ater quench) follo.ed 0y a tem-erin/treatment+

1he .ater quench results in the formation of martensite .hiletem-er,in/ treatment restores ductility and reduces hardness+ A -re,austenitizin/normalization cycle can 0e used to o0tain increased Char-y imtou/h,

ness -ro-erties throu/h recrystallization and /rain renement

Welding:

1he nominal com-ositions of 8&9% and ;*2% (Table 1) sho. th

8&9% is

more richly alloyed than ;*2%+ Gue to the metallur/ical mism0et.eenthe metals: ller metal(s) .ith a decreased C content and incrMncontent: .hen com-ared to the 0ase metals: is required+ 1hereduction inC content decreases the hardena0ility of the .eld metal (): there0y lessenin/ the li3elihood of crac3-ost,.eld+y reducin/ the hardena0ility: the -ro0a0ility of formin/ martdurin/the thermal cycles of .eldin/ is reduced+ 1he increase in Mncontent.ithin the .eld metal com-ensates for the lost hardena0ility -rovidin/solid,solution hardenin/: lo.erin/ of the tem-erature at .hich

austenitetransforms to ferrite and -romotin/ /rain renement : furtherim-rovin/stren/th+ A -reheat of at least 9%%HF (&%HC) and a ma6imuminter-asstem-erature of %%HF , *%%HF (2*%HC 9&HC) is required to-roduce sound.eldments7 1he choice of these tem-eratures is al.ays de-eu-onthe alloy(s) 0ein/ .elded+ Im-ro-er monitorin/ of thesetem-eratures may

S-ecial Gecem0er Issue J Kdition s-Lciale

GLcem0re 2%&8


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Ta+le 1: Ally C,-sitins ! "1#$ and %&'$

Figure 1: Standard Weld Joint Configuration.

Ta+le ': Welding .a/a,ete/s

lead to hydro/en crac3in/: usually .ithin the

and

de/radation of the mechanical -ro-erties+

For .eldin/ these materials: the /as tun/sten

.eldin/(D1A


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tment: and: as such: is availa0le in several heatted conditions+ In this case study: normalized:tenitized: and tem-ered ("P1) F22 .as used+

lding:

choice of .eldin/ -rocess and ller metal is of

icular im-ortance .hen qualifyin/ a 0utt .eldin/cedure .ith F22+ 1he nal .eldment .as required

meet '3si (2%M!a) for the yield stren/th andsi (*2%M!a) for the tensile stren/th+ In addition: the

end,user required that a ma6imum hardness 224$cma6imum in the 0e met+ 1o incrthe-ro0a0ility of meetin/ these requirements: th.eldller metal .as restricted to a ma6imum car0content of %+&.t: restrictin/ the e6tent of thmartensite transformation on coolin/7 too mumartensite .ill cause an increased hardness

2%

?@$"A

0rittle .eldment+ In addition: restrictin/ elements

such

as -hos-horus and sul-hur aided in the-reventionof harmful inclusion formation+ A -reheat of 8%%HF(2%8HC) and a ma6imum inter-ass of *%%HF

(9&HC).as used+ A/ain: the choice of thesetem-eratures isalloy,de-endant+

1o .eld F22 to F22: a novel .eldin/ -rocess: 1I!,

1ID:

.as selected+ 1his -rocess is a semi,automatedversionof the D1A< -rocess + 1he 1I!,1ID -rocess uses ahi/h,s-eed: linear .ire feed system+ 1his system-reheatsand ra-idly oscillates the .eldin/ .ire in and outof the.eld -ool resultin/ in the /eneration of thermalandmechanical ener/y and the reduction of -uddlesurfacetension'+ Also due to the additional: im-osedener/ies:the arc ener/y requirements are reduced resultin/in a

narro.er 4A> and lo.er inter-ass tem-eratures'+1hisis si/nicant since the 4A> is a re/ion of the .eldthat isty-ically -ro0lematic+ Finally: -roductivity isincreased.hen usin/ this -rocess 0y .ay of increasedde-ositionrates: travel s-eeds and: since less arc ener/y isrequired': lo.er inter-ass tem-eratures+

A standard V,Droove: full -enetration 0utt .eldcon/u,

ration .as utilized (Figure 1)+ 1he ma6imthat .asutilized durin/ all sta/es of .eldin/ .asaround 9'3?#in(&+83?#mm)+ 1he .eldin/ -arameters th.ere utilizedare summarized in 1a0le 8+ 1he .eld Boinrequired!


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-reheat and inter-ass tem-eratures and the needfor!


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S-ecial Gecem0er Issue J Kdition s-Lciale

GLcem0re 2%&8

Rt .ass Welding


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hardena0ility and solidication characteristics

the

t.o 0ase metals to 0e considera0ly di=erent+1y-icallyX*% is utilized in the non,!


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%HF%HC) .as com-leted on the *2 inlay+ It is im-ortantote that: as a result of this inlay !


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ARC EQUIPMENT

GAS APPARATUS

WELDINGAUTOMATION

CONSUMABLES

MANUAL PLASMA

CUTTING SYSTEMS

AUTOMATEDPLASMA


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Ta+le : AWS D1$*1% Suggested Heat In-ut

Ranges7.

Figure 6: Co$-leted Weld Joint /u-lex to

Su-erdu-lex StainleSteel &*)&* 10 Oxali! t!#.

Ta+le &: Welding ./8ess 9e/sus I,

and C//sin.e/!/,an8e*


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ses .ere com-leted usin/ semi,automated: -ulsed:D1A


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causin/ -oor .eldment quality+ ften: themanufacturertest re-orts (M1$) that are -rovided are notre-resentativeof the material as a .hole+ 1o avoid qualicationfailure:resultin/ in lost time and money: it is not onlyrecommended0ut necessary that all 0ase materials 0e tested-rior to.eld -rocedure qualication+ 1his ensures that it

is the.eld Boint that is 0ein/ tested: rather than the 0asemetal+

1he im-ortance of selectin/ the correct ller

metal andthermal cycle .as illustrated in case study &+ Inthis study:the .eldin/ of AISI 8&9% to AISI ;*2% .asdiscussed+ Forsuccessful .eldin/ of this dissimilar Boint: a llermetal.ith reduced C content is required7 this is toreduce the.eldment hardena0ility: aidin/ in the -reventionofmartensite formation durin/ the thermal cyclin/of.eldin/+ Carefully chosen -reheat and inter-asstem-era,tures further assist this martensite -revention as.ell ashel-in/ to avoid the formation of hydro/en

crac3s:ensurin/ the .eld maintains its mechanical-ro-erties+

1he selection of .eldin/ -rocess is another tool

that can

0e used to -roduce quality .eldments+ In 0othmediumalloy steels: such as AS1M A&;2 F22: and hi/hlyalloyedstainless steels: such as du-le6 stainless steel: thechoiceto utilize the 1I!,1ID .eldin/ -rocess .as made+In casestudy 2A: F22 .as 0utt .elded usin/ 1I!,1ID:-roducin/a .eld .ith a reduced 4A> .ith su-erior yieldandtensile stren/th+ 1he im-act tou/hness testin/resulted ina sin/le insucient test: therefore: .eldin/ -arameterandller metal modication is 0ein/ considered to

correct thisdeciency+

1he .eldin/ of stainless steels -rovided ao--ortunity toa/ain utilize the 1I!,1ID -rocess+ Gu-le6 asu-erdu-le6


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nless steel .eldin/ -resents an even /reater

len/en com-ared to .eldin/ the lo.er alloyed steels+/1I!,1ID -rocess for these alloys resulted in a 4A> ofreased .idth: .hich did not contain deleterioussesh as si/ma -hase and e6cessive -reci-itates+ 1hed

t also e6ceeded the mechanical stren/th and im-act/hness required 0y the end,user+ 1his .eldment:ned accordin/ to the AS1M D8;A test method:

orded.ei/ht loss+ 1hese results .ere a si/nicantrove,nt over -erformance of .elds com-leted usin/ thei,automated D1A< .eldin/ -rocess+ Additionally: aicant im-rovement in -roductivity .as noted+

ome cases: a non,standard .eld Boint must 0e

sidereden the alloys to 0e Boined -ossess si/nicantlyerentda0ility+ In case study 2: the Boinin/ of F22 and X*%required7 in this case it .as also necessary to inlay

material .ith Inconel *2 for corrosion resistance+

alloys: F22 and X*%: have con5ictin/ .elda0ilityerequires !

studi kasus heat treatment pada baja asi

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