1
Linking Processing, Microstructure and Property
Models
2
g
g
a
a
a
20 nm
3
Carbon supersaturated plate
Carbon diffusion into
Carbon diffusion into
austenite and carbide
austenite
precipitation in ferrite
Carbide precipitation
from austenite
LOWER BAINITE
UPPER BAINITE
(Low Temperature)
(High Temperature)
4
Swallow and Bhadeshia, 1996
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(No Transcript)
6
Peet, Babu, Miller, Bhadeshia, 2004
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(No Transcript)
8
(No Transcript)
9
(No Transcript)
10
(No Transcript)
11
Okabayashi and Tomita
12
1 µm
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brazing data from Bredzs Case
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Young Bhadeshia
15
Young Bhadeshia
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Young Bhadeshia
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(No Transcript)
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hard phase elastic, soft phase plastic
average plastic strain
elastic constants
stress, hard
flow stress, soft
fraction hard
19
hard phase yields at a lower stress than in
homogeneous sample
soft phase yields at a higher stress than in
homogeneous sample
20
(No Transcript)
21
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22
g
g
a
a
a
20 nm
23
transformation-induced plasticity
24
general invariant-plane strain
simple shear
uniaxial dilatation
s
s
d
d
1
1
1
s0.26 d0.03
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Bhadeshia, 1982
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(No Transcript)
27
polycrystalline austenite
s
50 mm
Bhadeshia, 1982
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(No Transcript)
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z3
z1
30
v
u
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Sakuma et al. (1991)
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Need to improve mechanical stability of austenite
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Very poor toughness!
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50 µm
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(No Transcript)
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Impact Energy
Test temperature / C
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Hard Bainite
m1/2
18 wtNi maraging steel

MPa
Fracture toughness /
QT
Ultimate tensile strength /
MPa
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(No Transcript)
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g
g
a
a
a
20 nm
41
2500 MPa, 40 MPa m1/2
42
Scifer, 5.5 GPa with ductility!
Kobe Steel
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1 Denier weight in grams, of 9 km of fibre
50-10 Denier
Scifer is 9 Denier
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700
600
500
400
o
B
350
C
Temperature/ oC
S
300
200
o
M
120
C
S
100
0
1.E00
1.E02
1.E04
1.E06
1.E08
Time / s
45
thank you !