Weld Cracking in a Cast Ni-based Superalloy
Transcript of Weld Cracking in a Cast Ni-based Superalloy
Weld Cracking in a Cast Ni-basedSuperalloy
Sukhdeep Singh1, Joel Andersson2
1. Department of Industrial and Materials Science, Chalmers University of Technology, Sweden
2. Department of Engineering Science, University West, Sweden
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Hot Structural PartsShaft
Vanes
Fan/compressor structures
Turbine structures
Compressor rotorsCombustor structure
LPT-Case
Fan Case
Introduction
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Composition in wt%
Ni Fe Cr Co Nb Mo Ti Al … Si B
Cast 282 Bal. 0.1 19.4 10.2 0.1 8.4 2.12 1.5 … 0.01 0.005
Cast 718 52.98 Bal. 18.11 0.07 5.30 2.98 0.99 0.42 … 0.07 0.03
Haynes® 282®
Alloy 718
Strengthening phase
γ´ (gamma prime)
γ´´ (double-prime)
Segregating phase
Mo-enriched
Nb-enriched
Cast Haynes® 282®
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Heat Treatments
As Cast
1120°C/4h
1160°C/4h
1190°C/4h
1135°C/0.5h
Pseudo-HIP
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Research Objective
How different heat treatments affect the HAZ liquation crackingsusceptibility of cast Haynes® 282® ?
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Heat Treatments
1120°C/4h
1160°C/4h 1190°C/4h
As Cast
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Heat Treatments
1120°C/4h
1190°C/4h
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Parameters: Welding Speed = 1 mm/s
Stroke rate = 10 mm/s
Current = 70 A
Arc =2 mm
Ar gas flow = 15 l/min
Radii: 60,100,150 (mm)
Varestraint Testing
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HAZ Cracking
1.0 1.2 1.4 1.6 1.8 2.0 2.2 2.4 2.6 2.8
0
1
2
3
4
5
Avg
.TC
L(m
m)
Augmented Strain (%)
As Cast
1120°C/4h
1160°C/4h
1190°C/4h
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Avg.TCL
1190As Cast 1120-1160
As Cast 1120°C/4h 1160°C/4h 1190°C/4h
GS 1.6±0.4 1.5±0.2 1.6±0.3 1.6±0.2
HV 245±40 215±10 230±20 220±10
Vv% 1.5±0.2 0.9±0.1 0.7±0.1 0.5±0.1
HAZ Cracking
°C
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Avg.TCL
1190As Cast 1120-1160
HAZ Cracking
°C
As Cast 1120°C/4h 1160°C/4h 1190°C/4h
GS 1.6±0.4 1.5±0.2 1.6±0.3 1.6±0.2
HV 245±40 215±10 230±20 220±10
Vv% 1.5±0.2 0.9±0.1 0.7±0.1 0.5±0.1
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Avg.TCL
1190As Cast 1120-1160
HAZ Cracking
°C
As Cast 1120°C/4h 1160°C/4h 1190°C/4h
GS 1.6±0.4 1.5±0.2 1.6±0.3 1.6±0.2
HV 245±40 215±10 230±20 220±10
Vv% 1.5±0.2 0.9±0.1 0.7±0.1 0.5±0.1
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Avg.TCL
1190As Cast 1120-1160
HAZ Cracking
°C
As Cast 1120°C/4h 1160°C/4h 1190°C/4h
GS 1.6±0.4 1.5±0.2 1.6±0.3 1.6±0.2
HV 245±40 215±10 230±20 220±10
Vv% 1.5±0.2 0.9±0.1 0.7±0.1 0.5±0.1
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• Objective :
• Primary : recorded B distribution in grain boundaries, variations among heattreatments
• Secondary : Si and P imaging
• Conditions :
• 1120,1160,1190°C/4h
NanoSIMS Analysis
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NanoSIMS analysis at 1120°C
C Si P
B
0.0 0.5 1.0 1.5 2.0
0
200
400
600
800
1000
1200
Inte
nsi
ty(C
ou
nts
)
Distance (µm)
11B12C2
3-4
Carbon Boron
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NanoSIMS analysis at 1160°C
C Si P
B
Carbon Boron
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NanoSIMS analysis at 1190°C
C Si
P B
0 1 2 3 4 5 6
15
20
25
30
35
40
Inte
nsity
(Cou
nts
)Distance (µm)
11B
0 1 2 3 4 5
15
20
25
30
35
40
45
50
Inte
nsi
ty(C
ou
nts
)
Distance (µm)
11B
0 1 2 3 4 5
15
20
25
30
35
40
45In
ten
sity
(Co
unts
)
Distance (µm)
11B
1-2 3-4
5-6
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Hot Ductility - On Heating
Gleeble Parameters:
Heating rate
Peak temperature
Stroke rate
Holding time at peak temperature
Holding time at test temperature
111 °C/s
1200 °C
55 mm/s
0.03 s
0.03 s1050 1100 1150 1200 1250
0
10
20
30
40
50
60
70
80
90
W. 282 On-H.1120°C/4h1190°C/4h
Are
aR
ed
uct
ion
(%)
Temperature (ºC)
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Hot Ductility - On heating at 1150°C
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Hot Ductility - On heating at 1200°C
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Summary
• Ranking according to Varestraint weldability study:• 1190°C/4h higher cracking• 1120-1160°C/4h lower cracking sensivity
• NanoSIMS analysis:• B is found only in compound at 1120° and 1160° together with C• B segregates at the grain boundaries at 1190°• Complete dissolution of C-B particles and the segregation at the grain
boundaries contributed to exacerbated HAZ cracking
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Thank You!
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• Occurs during cooling from hightemperature due to diffusion of vacancy-solutes to vacancy sinks
• Increases with increasing temperature
• Occurs when a material is held at hightemperature sufficiently long to permitappreciable diffusion of solute atomsfrom the matrix to the grain boundaries
• Decreases with increasing temperature
Equilibrium vs Non-Eq. Segregation
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NanoSIMS analysis at As cast
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NanoSIMS analysis at As Cast
C Si P
B
0 1 2 3 4
0
5
10
15
20
25
30
35
40
45
50
55
60
65
70
75
80
Inte
nsi
ty(C
ou
nts
)
Distance (µm)
11B
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NanoSIMS analysis at 1160°C
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NanoSIMS analysis at 1160°C
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HAZ Cracking
HAZ FZ HAZ FZ
1120°C/4h 1190°C/4h
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Hot Ductility - On heating at 1200°C
1120°C/4h
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Mo-rich precipitates
As Cast 1120°C/4h 1160°C/4h 1190°C/4h
Vv Mo(%) 0.14±0.2 0.31±0.2 0.13±0.2 00±00
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On-Heating/On-Cooling f(B)
Influence of B content on Hot Cracking sensivity of weld heat affected zone in Incoloy 800Saito et al., Transactions ISIJ, Vol. 27, 1987
1050 1100 1150 1200 1250
0
10
20
30
40
50
60
70
80 Wrought 282As Cast1120°C/4h1160°C/4h1190°C/4h
Are
aR
ed
uction
(%)
Temperature (ºC)
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Hot Structural PartsShaft
Vanes
Fan/compressor structures
Turbine structures
Compressor rotorsCombustor structure
LPT-Case
Fan Case
Introduction
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Heat Treatments
1120°C/4h
1160°C/4h
1190°C/4h
As Cast
0.9±0.1
0.7±0.1
0.5±0.1
1.5±0.2
1.5±0.2
1.6±0.3
1.6±0.2
1.6±0.4
215±10
230±20
220±10
245±40
Vv% GS HV
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Heat Treatments
1120°C/4h
1160°C/4h
1190°C/4h
As Cast
0.9±0.1
0.7±0.1
0.5±0.1
1.5±0.2
0.31±0.2
0.13±0.2
00±00
0.14±0.2
1.5±0.2
1.6±0.3
1.6±0.2
1.6±0.4
215±10
230±20
220±10
245±40
Vv% Vv Mo% GS HV
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Avg.TCL
1190As Cast 1120-1160
HAZ Cracking
Boron
Enrichment factor: grain size, starting temperature, coolingrate…
Karlsson, Non-equilibrium grain boundary segregation of B in austenitic stainless steel_III.Computer simulations, Acta metall. Vol. 36, 1988
Enrichment factor: grain size, starting temperature, coolingrate…
Karlsson, Non-equilibrium grain boundary segregation of B in austenitic stainless steel_III.Computer simulations, Acta metall. Vol. 36, 1988
Peak Temp.: NDT+50
0.01 B0.002 B
West, S.L. Phd Thesis, A study of weld heat-affected zone liquation in cast nickel-base superalloys,The Ohio State University, 1991.
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Stress relaxation through liquid
TCL
Liquid film thickness
σ = 2γSL/h
1120
1190
As Cast ??
(50nmresolution)
Moveable
Primary Ions (PI)
Secondary Ions (SI)
SampleSurface
SIMS NanoSIMS
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Outline
• Introduction
• Experimental
• Results & Discussion
• Summary
• Future Work
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It is function of:• Heat treatment temperature• Cooling rate• Concentration of solute atoms• Binding energy between solute atoms and vacancies
Karlsson, Non-equilibrium grain boundary segregation of B in austenitic stainless steel_III.Computer simulations, Acta metall. Vol. 36, 1988
Non-equilibrium segregation
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• High tendency of B to segregate at the grain boundary vacancies• Surface active element affecting the grain boundary wettability
Varestraint Testing
• Cracking increases • Reduces the NDT and NST• BTR increases
Gleeble Testing
Effect of B on weldability
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• SETTINGS :
• Implantation 1017Cs+.cm-2 with D11 and ~ 180pA
• ES4 AS3 EnSopen, mass resolving power is put at ~10000
• mass table for (11B-), 11B12C-, 12C-, (12C2-), 28Si-, 31P-, 11B16O2-
• Current measurement ~ 1pA with D12,
• SAMPLES :
• As Cast, 1120,1160,1190°C/4h
• Objective :
• Primary : recorded B distribution in grain boundaries, variations among heattreatment
• Secondary : Si and P imaging
NanoSIMS for B analysis