1. Silicon-Rich Bainitic
Steel Welds
M. Lord
L.-E. Svensson

2. Previous work
Inspiration from steels
Novel weld microstructure
Two weld design models
Experimental results
Difficulties

3. G. M. Evans, Metal Construction, 1986Mn
Si wt%

4. 100 µm

5. Allotriomorphic ferrite Widmanstätten ferrite Acicular ferrite
Microstructures:
Allotriomorphic ferrite
Widmanstätten ferrite
Acicular ferrite
Recrystallise easily

6. Carbon supersaturated plate
diffusion
Cementite
precipitation
UPPER BAINITE
LOWER BAINITE

7. g g a a a
20 nm

10. 50 µm

12. T-zero curves

14. kilocycles to Crack Initiation
Pearlite
Martensite
Bainite
1200
1000
800
600
400
200
kilocycles to Crack Initiation
Yates, Jerath

15. Yates, Jerath

17. Design criteria for welds
T0 curve at high carbon
Sufficient hardenability

18. MULTIPASS ARC WELD
L.-E. SVENSSON

19. 20 µm
Barrite, 1982

21. Manual Metal Arc Weld
Amps
34 Volts
4 mm/s
200 °C interpass

22. calculations 800 700 600 Temperature / C 500 400 300 2001 3 4
700 5 6
600
Temperature / C
500
1. Fe-0.4C
2. Fe-0.4C-2Si
400
3. Fe-0.4C-1Ni
4. Fe-0.4C-1Mn
5. Fe-0.4C-1Mn-1Cr
300
6. Fe-0.4C-2Mn
200
Time / s

24. Bhadeshia & Svensson, 1989

25. Fe-1Mn-C wt % manual metal arc welds
0.2
0.4
0.6
0.8
1.0
Allotriomorphic
Volume fraction
Widmanstatten
Acicular
0.11
0.09
0.07
0.05
0.03
Carbon / wt %

27. wt%

37. equilibrium Si Fe

38. paraequilibrium Si Fe

41. Weld microstructures, with good properties, containing mixtures of austenite and bainitic-ferrite can be created.
Data and theory for silicon in steel needs improvement

42. Best wishes for the next 30 years