Predicting the Microstructure and Properties of Steel Welds.
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Transcript of Predicting the Microstructure and Properties of Steel Welds.
Predicting the Microstructure and
Properties of Steel Welds
MULTIPASS ARC WELD
L.-E. SVENSSON
L.-E. SVENSSON
a
ca
yx
z
100 µm
20 µmBarrite, 1982
120100806040200200
400
600
800
1000
Time / s
120100806040200200
400
600
800
1000
Time / s
Manual Metal Arc Weld
180 Amps
34 Volts
4 mm/s
200 °C interpass
Manual Metal Arc Weld
180 Amps
34 Volts
4 mm/s
200 °C interpass
12
3 45
6
1. Fe-0.4C2. Fe-0.4C-2Si3. Fe-0.4C-1Ni4. Fe-0.4C-1Mn5. Fe-0.4C-1Mn-1Cr6. Fe-0.4C-2Mn
0 1 2 3 4 5 10 10 10 10 10 10
Time / s
800
700
600
500
400
300
200
Tem
pera
ture
/
C
calculations
Barrite, 1982
5 µm
Barrite, 1982
0.110.090.070.050.03
0.2
0.4
0.6
0.8
1.0
Carbon / wt %
Volu
me f
ract
ion Allotriomorphic
Widmanstatten
Acicular
Fe-1Mn-C wt % manual metal arc welds
Bhadeshia & Svensson
Bhadeshia & Svensson
Charpy toughnes
s
Murugananth & Bhadeshia
7Ni 2Mn
7Ni 0.5Mn
7Ni 2Mn
7Ni 0.5Mn
Weld Shape - Stitch Weld at 2.26 kW Laser OutputWith Ar shieldinggasv=45 mm/s; L=5mmv=45 mm/s; L=5mmv=45 mm/s; L=10mmv=40 mm/s; L=15mmv=50 mm/s; L=15mmv=50 mm/s; L=15mmv=40 mm/s; L=20mmv=35 mm/s; L=10mmv=27 mm/s; L=10mmv=35 mm/s; L=5 mmv=27 mm/s; L=5 mmv=50 mm/s; L=20mmWithout shieldinggas2 mm
PARTIALPENETRATIONFULLPENETRATION2.26 kW LASER BEAM
Laser beam
Keyhole
Laser beam
Fusion Zone
m
w
Optically: mainly -ferrite some w-ferrite <5% martensiteTEM: -ferrite much w-ferrite
155, 157 and 170 HVMean Hardness: 161 HV
Grain size100 ±20 m
46% -ferrite21% w-ferrite30% acicular ferrite & bainite 3% martensite
168 HV
Grain size103 m
Measured Calculated
Charpy
fatigue
corrosion
tensile
critical stress intensity
Variables
• C, Mn, Si, Ni, Cr, Mo, V, Co, B, N, O…..
• Thermomechanical processing of steel
• Welding consumable• Welding parameters• Subsequent heat treatment
Empirical Equations
y = a + b (%C) +c (%Mn)
+ d (%Ni) ....
y = a + b (%C) +c (%Mn)
+ d (%Ni) ....
1223
y = a + b (%C) +c (%Mn)
y = a + b (%C) +c (%Mn)
+ d(%C x %Mn)
y = a + b (%C) +c (%Mn)
y = a + b (%C) +c (%Mn)
+ d(%C x %Mn)
y = a + b (%C) +c (%Mn)
y = a + b (%C) +c (%Mn)
+ d(%C x %Mn)
y = sin (%C) + tanh (%Mn)
y = a + b (%C) +c (%Mn)
y = a + b (%C) +c (%Mn)
+ d(%C x %Mn)
y = sin (%C) + tanh (%Mn)
Hyperbolic Tangents
y
f{x }j
1
2(a) (b)
non-linear functions
765432100
1
2
3
4
5
6
7
x
86420-100
0
100
200
300
400
x
86420-100
0
100
200
300
400
x
86420-100
0
100
200
300
400
x
Complexity of model
test error
training error
(a) (b)
(c)(d)
Predict what the next two numbers are likely to be:
2, 4, 6, 8, …….
0.0 0.2 0.4 0.6 0.8 1.00
50
100
150
200
250
300
Nickel / wt.%
10CrMoW
104 h, 550 °C
0.00 0.02 0.04 0.06 0.080
50
100
150
200
250
300
Aluminium / wt.%
10CrMoW
104 h, 600 °C
Brun, Robson, Narayan, MacKay & Bhadeshia
precipitates
solid solution
iron + microstructure550 °C
600 °C
Murugananth & Bhadeshia
Components of Creep Strength, Components of Creep Strength, 2.25Cr1Mo2.25Cr1Mo
0 5000 100000
100
200
300
400
Life / hours
GTA weld at 923 K (data from Nippon Steel)
Cole & Bhadeshia
Cool, 1996
Cool, 1996
As-welded 600 °C
650 °C700 °C
Cool, 1996
Siemens
Mitsui Babcock
Nippon Steel
ABB
Thank you.