Simultaneous Transformation Kinetics

1
Simultaneous Transformation Kinetics

• Avrami theory
• Adapted for many reactions occurring together
• Ferrite, Widmanstatten ferrite, pearlite.
• Complex carbide-precipitation reactions
• Competition between inter- and intra-granularly
  nucleated reactions
• Some difficulties

2
DISPLACIVE
RECONSTRUCTIVE
3
1.00

Allotriomorphic
PREDICTED FRACTION

Widmanstatten

Pearlite
0.75
0.50
0.25
0.00
0.00
0.25
0.50
0.75
1.00
MEASURED FRACTION
Jones Bhadeshia, 1996
4
?
?
?
?
?
CONSTRAINED
UNCONSTRAINED
5
100 microns austenite grain size
PEARLITE
?
w
11 K/min
?
101 K/min
Jones Bhadeshia, 1996
Temperature / C
6
30 microns austenite grain size
PEARLITE
?
11 K/min
?
w
101 K/min
Jones Bhadeshia, 1996
Temperature / C
7
Robson, Jones Bhadeshia, 1996
8
Steel F (10Cr1MoV)
Robson Bhadeshia, 1996
9
Baker Nutting 2.25Cr1Mo Steel
Robson Bhadeshia, 1996
10
NF 616
Robson Bhadeshia, 1996
11
Driving force for M2X precipitation
Robson Bhadeshia, 1996
12
Steel F (10CrMoV)
Robson Bhadeshia, 1996
13
M2X precipitation
Robson Bhadeshia, 1996
14
M23C6 precipitation
Robson Bhadeshia, 1996
15
Laves phase precipitation
Robson Bhadeshia, 1996
16
Robson Bhadeshia, 1996
17
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18
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19
Kasuya, Ichikawa, Fuji and Bhadeshia, 1999
20
Kasuya, Ichikawa, Fuji and Bhadeshia, 1999
21
0.7
0.6
Prestrain
0.5
0.0
0.4
0.18
0.3
0.36
0.2
0.63
0.1
0.0
Singh Bhadeshia, 1996
0
100
200
300
400
500
600
Time / s
22
0.7
Prestrain
0.6
0.0
0.5
0.4
0.63
0.3
0.2
0.1
0.0
Singh Bhadeshia, 1996
0
100
200
300
400
500
600
Time / s
23
M
of the alloy
s
400
350
300
0.0
0.2
0.4
0.6
Singh Bhadeshia, 1996
Prestrain
24
o

500
C
o

475
C
0.6
o

450
C
o

400
C
0.4
0.2
0.0
0.0
0.2
0.4
0.6
0.8
1.0
Prestrain
25
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