Cold-Cracking Control in Low-Alloy Steel Welds
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Transcript of Cold-Cracking Control in Low-Alloy Steel Welds
McMaster UniversityDigitalCommons@McMaster
Open Access Dissertations and Theses Open Dissertations and Theses
9-1-1979
Cold-Cracking Control in Low-Alloy Steel WeldsVivek Pavaskar
This Thesis is brought to you for free and open access by the Open Dissertations and Theses at DigitalCommons@McMaster. It has been accepted forinclusion in Open Access Dissertations and Theses by an authorized administrator of DigitalCommons@McMaster. For more information, pleasecontact [email protected].
Recommended CitationPavaskar, Vivek, "Cold-Cracking Control in Low-Alloy Steel Welds" (1979). Open Access Dissertations and Theses. Paper 2753.http://digitalcommons.mcmaster.ca/opendissertations/2753
McMaster Univer~ity ~
Handlton; Ontario•r ..
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S.eptembcr 1979
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LOW-ALLOY S'1'E!:L WELDS
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. ' . - .MSUR Of' DCD+Rnax: (197'9)
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(MetaUurcJY aDd ICateria1.a SC1eftCe) . -
AT11'HOR:
SUPERVISOR:
Vivek Pavaskar. B.'1'ech. (I~ InSt!tute of'recbnology. BcGlbay)
Dr. J _ S. JCirkaldy
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BAZ microst:ructure" s~ess anc1'1-lyckogen level a~.,the-fun~n-, \ -
t&J. faet="<; tDt'l~5!"'. cold '~rac:1dng s""ceptihlUty '~l1:he RAZ. •
Implant testin~4't:v ~ ious hYdroqen leve'1.s over A range of steel. CCIIIpO-
I, , ':. . ...
sition~ and he 1n s ..shows how the ~mi.cros~ctur~~.hydrogen, ,~'
level influence the cx::itic4l -stress necess~ry for cold-cracking.
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•. 'Based on implant test da~cr. 4 cOrrelation fOrlUula prC'dieting. the. ~ ,
, ~critical stress necessary for cold cracking for given HAZ ~ness. ,
he~ transfet ~alculations. , martensit~~si-
'"marten'site in the HAZ -4nd hydrogen -revel, is proposed. Elnpioying this. ....... ,w~ prediction'of ~ mar~e~te 'in the ~AZ'and,. .
correlation. together
~'HAZ hardness. ~ed on ..
.\ tion-cooling rat~ relations anc h~rdness-compositiOn-cooi~grate.r~la-"
tions, an algorith~ which can p!cdict the criti~al stress necessary for
~)cracking f~ given implant c~~p~~it~on, cooling rate and hydrog~n level,
.p
is constructed.•
....niis, method of predicting the-critical stress'necessary for cold
cracki.ng is an improvem~nt over tht: ex.isting regression formulas fo'l;
,~. ,-
estindting cold-,racking susceptibility., . ~ .
This formula has been s~cJ~5sfullY addpt~d to predict cold-crack-
ing susceptibility data as obtained through'othe~ test~ such as rigid
rcstraiot~ and to re~omme~d preh~a~,levels necess~~y to aV~d cold-crack-
ing. Development and use of <l:"l inplant t~sting machine ""ith·-an automatic
w~ldin9 and loading facility i~ al~o reported.
I'n
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........ . ......'1'be.. abthoc.1a indebted ~to his aaperviaor, Dr. J. S. J:1%'ka1dy,,
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for ~u1jges~n9'~p~oblelD de< ~th here~ ~ 'for hia cont.iJluoua- ... •• .. 1# •
9ui~ance throughout the course of this ~rk. 'nlanks. are a1.so'due to
"many\ of t~ ,s~tf.and gradUoite students in the De-partment of Meta11urgy
and-~teria.fs S<:~ence. for their advice and assistance. X wou1d al.so
like to thank the technical staff of the Department of Metallurw and
.Materi~ls SCience.'~~ the machine shop for their assjstan<:e in de-
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veloping the lmpl~t ~sting Equipment, Thanks are also due to Mrs.
S~ Saracini'f~ the excellent typing 'of this thesis./'", , .
~<:ial suppOrt of the Natural Sciences and Engineering
Research Couneil of Canada is gratefully acknowledged ../
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OIAP1'ER 1 .IN'l'RODOCTION 1
• •CHAP'1"ER 2 ASSESSDlC THE C;:O~RACnNC. SUS~arLITY OF THE HEAT ,
. .AFP'EX:"tEO ZONE (HAZ) IN S'l"EEL t~LC:~:TS
'-.
2.1 Weldability Formulas for !,-ssessi{\g Cold~rackinq
Susceptibility/
4
2.2 Implant Testin; for Assessin;.Cold-cra~kin~·
: Susceptibi li t.y . 15J
CHAPTER 3 INFLUENCE OF HAZ r-~ICR05'!'ROC'I'URE .;.:::> HYOROGEtl LEVEL ON, ,
3.1• •
Correlatio~ For~~ Base~.o~ !~lant. Test Data.. 19
3.2 Influence of ·~~z , ~~rtc~sitc ~~d Harcness on aCR
20
3. 3· (' ~.odi f i ed' Corre l~ ti·cnt"Forr..u Ill, . : or aCR
3.~ ROle of.Hydro~en in A:f~c~in~ o. •. c~ .
23
25
3.4.1 Calcula~ion o~ Hydrog~n Concentration and•, . . '
Str*:;ss I::tensity in tl'\t: ~egion of Haximum
Tria~ial i ~y" 36
3.4.2 Discussi~~. , . 38
CHAPTER ~ ~R-~ICTION O~ 0 . O~ TH~ BAS!S 0; ~~~7 ·tNPG1, PLATECR .~
pred~tiono! ~~~~ hffcc~d Z~n; Cooling Rate
4.2.1 He<lt-.Tran:ifer wit'h 30"r.",=,H. Fl'Ow
42
46
o• •
4,_2..1.1 Applic<ltio:'\ 0: 3:) HC<1t F.lm" Relation~
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51
PACZ,';-
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2D, Heat Flow
2.SD Heat Flow .
4.2.2 Heat 'transfer With
4.2.~ Heat ~~sferli~( .4.2.4 Craphi~~l Representation of Heat Flow
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Conditions as a Function of Plate 'l'hiclcness 52
."4.2.5 Procedure for Preaicting Cooling Rate 53
4.2'.6 Discussion
4.3 Prediction of Heat Affected Zone Microstructure
55
4.3,i , Klcroconstituent -.Composition - COoling,Rate R~lations 57
4.3.2-Hardness - Composition -'Cooling Rate
Reiationst
59
;(--4.3.3 Prediction of HAZ , Martensite and Hardness, w
59
4.3.4 Discussion 63
CHAPTER 5 DETERMINATION OF PRACTICAL WELDING PROCEDURES ON THE
BASIS OF IMPLANT TEST 82
5.1 General Remarks 82
5.2 R~lation Between Implant Test and Otht!T kstraint
Tests 82
'5.3 Determination of Prehea.t to Avoid Cracking 84
5.3.1 Estimation of Reuction Stress Developed in
the Welc 87 .'5.3.2 Influenc~ of Preh~dt on Resicual Hydrogen
Level 88
5.'.3 Prediction of Prehedt Level to Prcv~nt Crucking 91
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CHA?:=:~ 7 CONCLUSIONS
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110
110
110
111
113
113
115
115
120
126
126
- 133
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6.2.3 The Pressure Systeo for the Implant Test
6.2.1 AutO!Datic Deposition of ~.5MAW Electrodes
6.2.2 '!'he Il:lpl4nt Loadinc;'S~tem
6.3.2 Implant 7est'Details.
6.3.1 Welding Con~tions
6.4 Prelic1nary ?ests
6.5 DisCI..-ssion
6.3 Standardization of the- Iop1a."1': Testing Procedure
6.1 General Remarks
~.2 ~sign of th"e ~lant Testinc; Machine
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APPEt'DIX I 1-3§
APPENDIX II 137
APPE~:Dn: III 139
REFE~JCES ~ 144
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LIST 'OPTJU3LES
TABLEi
PACE
,
Steel weldments
1
2
3
5
6
7
8
9
10
Formulas Develo~ to Assess Cold-craddng of HAZ in, , ~
•~ldin<J Precautions for Various carbon
Equivalents
~~~litY Index Proposed by Bradstreet
Re1.a.t.ion Between carbon Equivalent and weldability .
.Inde~ fo~ Low Hydrogen Electrodes
Weldin~ Procedure,for Prevention",of Cold-Cracking
'~ristensen's Implant Test' Datd \
Comparison Between Our's and Christensen's Correlation
Influence of Hydrogen Lever on,oCR
Calculated Stress Intensity and HeR Level~ ,at 0C~
Comparison Between Reported dnd Calculated Cooling
.I
6-7'::'
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10
10
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26 •" '31
39J
Times' Between 800°C - 500·C .. 56
11 Prediction of OCR o~ ~e Basis of Heat Input, ~late
Thickness, Plate Co~position and Hydrogen Leve~
"12 Prediction of HAZ Hdrdn~ss and OCR for the Ito-Bcssyo
Data 73-81
13-16 Prchaat Levels Predicted for Various-Steel Compositions,
Plate Thickness, Heat Inp~t, ~nd Hydrogen Level With
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Fillet Weld Configuration
Welding Hcat Input Details
viii
102-109
116
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.19
t)- . .
Compar~ Be~ (bserved &.~d·?:~c:ted Coo~
. tiJDeS~4 eoo.~·C - _soo·Ct
0Mtmic:al CoD:posi.tiCXlS of ...the Steels used for
_ l)apl.ant: Testing
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PACE--..123·
.129
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..PACE
1
2
3
5
6
7
8
9
10
11
12•
13
14
Bai.ley' s (14) Nomog%4JD of safe Welding Procedures
for C-Mn Steels
Ito-Bessyo (1'6) System for Determining' safe Weldi.ng
Procedures
!m;)lanting Steel .Specimen by Welding'
SChematic Diagram Showing Implant Te9t
Typical Stress VS Fracture Time Curve fo'r an
"Implant Test .. (23)
Variati~~ of 0ck With HAZ Hardness
, Weld Cracking and HAZ Hardness Plot C1S)
'COrrelation Between OCR and Both , Martensite and
Hardness as Parameters
Correlation Between OCR and HAZ INDEX
COmparison Between COrrelated and Observed 0C~ With
, Ma~site ,as p~~ter
Comparison Between Correlated and Observed ° WithCR
, Martensite and Hardness, as Parameters
Influence of Hydrogen Level on OCR
Variation of Hydrogen Index Wi th HydrC?3en Level
,Stress Intensity and Hydrogen Concentration Combina- ...
12
14
16
16
17
21
22
27
29
30
32
33
'\
tions for Fracture(4)
as Suggested,~y Beachem...
15 Influence of Notch Radius on the Location of the
Hy,drogen Assisted • C35)Crack1ng ,-
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37
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18
19
20
21
22
23-25
CUWbiua' of St:ress."Intensity· and~~ ".' .-
.CoDceDt:raj:ion~critical ~ion at (Sea
'Block D1a~"for PridictiDg (Sea on the Ba~~ of ... -~ ........."
Wel.di:D9 Beat anput, Plate Thickness," Plate C'omposi-.....
tieD.. and Hydrogen Level~
Beat F~9'" Cone.it:i.ons in Welding
vari&t5:-on. of~A3D .with:- . . ~
varla~~- of B3D with
va.r~ation of Coo1i:lg Rate 'with Plate ickness (~l) ,
Tr· f .' d Cool' . Cha (42).ans ODDa:'t:ion an ~ng Rate· rtJ ":-
" Martensite and Cooling Rate ~s for Three c-Mn
SteelS'
40
49
54
58
61-62
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26 . Cqmpa.rison Between predicted and Observed " Martensite
.' (for.Christense:\"s :,)ata(22,23»'.'.
27 ~ison Between Predicted ·A."\d ObserVed HAZ H~dness
(fOr Christensen's Data(22,23» ..
'64
65
....
28
29
30
". "31
Cpmparison .Beo.:ee,n 'Predicted A."\d Observed RAZ Hardness
(f. (lS} .
or lto-~ssyo . Data)
...C~ison Between'Predicted and Observed OCR (for
Chri~tensen's(22). Data)
, Plot of " weld Cracki:\g ~gainst Predicted 0CR'!for
lto-Be~'SYO(15) Data)
. (15tPlot of " Weld Crac~ing ~gainst Ito-Bessyo Cracking..Parameter Pc
66
68
69
'70
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P:tGORE
32 CoIIIpari.saD Between Lower Critical. .Fra~ S~.
Obtained frcm Implant '!'est and from RIC and TBr:::
'.Tests
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'34
350
Critericn £or A'V'Oiding Cold-Cracks in Welded
Structures
Procedur; fOr Rec:ommend.ing Preheat.to A'V'Oid Cracking
. ~Intensity of Restraint vs Plate Thickness for Welded
85
86
- (43)Construction
1.
-.89
•36
37-44
45
46
47
Bead .Model for Bydrog~..Diffusion Analysis
CompaJ';~son Be.bleen Predicted Preheats and ReCOlllJDended
(B.S. Standard) Preheats
System for AutOmatic Deposi ti6n of MSMAW Electrodes
Implant l.oading System .-Pre~~e System for Implan~~est
89
94-107
112
114
114.. <
48 General View of the Implant Tes~ing Equi~nt Complete
Wi th ~utomatic Weldi~g ana Loading Facility 117
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49
so
51.
S2
53
5~
- .Details of the weld;ing Arrangement
Detailed View of the Loading System
Weld Bead Sections for Three Heat Inputs
Typical Thermal Cycle Profile in Welding
Implant Specimen Details
.Base Plat~ Used for Implant Test
118
119
121
122
124
125
•55 Section of Implant Specimen Showing the Location
•of the Notch 127
56.
. Typical Variation of Hardness Across the ~eld
xii' •
128
58
57
·FIGtIBE
Stress-Pra~~Diagam for St2e1 No.:
~-Fra~e ~~gram"~or 'S~l 50.
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CHAPTER 1....
Hydrogen induced cold-crac:king has ~n one of the .major problems'
~n~ ~ls. ~c:ks of this' type can take many fonlS _ although
they have some qene.r'a1 characteristics and are influenced by CO""IDOn
basic factors.
, As the name implies, these cracks form at low temperatures
generally below ~OOOC, and often exhibit a delay phenomenon. Even after
the weld has cooled to room temperature, there may be a further lapse of
time ranging from a' few minutes to severa1 hours.
Cold~cracks ~re not tolerated in a.structure, and since they are
'0.
..often' difficult to detect and expensive to repair, it becomes essential
fo~ the fabricator to take precautions during welding to prevent their
formation,J
Even though the general causes of hydrogen cracking and the means
of preventing these cracks are known" recent industrial surveys have
shown that cold-cracking is ~till widely encountered, indicating that
the ability to satisfactorily predict cold-cracking susceptibility has.
not been developed.
Hence, development of a t'el;'able, quick and economic method for
predicting hydrogen craclcing in a real welded.. joint is desirable to 00-
termine when conventional welding techniques can be used wi thout the
likelihood of failure from hydrogen cracking. In addition, needless
expense of preheating and low-hydrogen techniques cou1d be avoided; re-
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