1. Interstitial-Free Steels: Structure of Spot Welds

2. Interstitial-free steel Fe-0.002C wt% Interstitial-free and unalloyed

4. Extremely fast transformations Extremely fast cooling rates Phase diagram similar to pure iron Difficult to interpret structure

5. Interstitial-free steel Fe-0.002C wt%

6. Bundy (1965)

9. J. Khan, L. Xu and Y. J. Chao, Science and Technology of Welding and Joining 4 (1999) 201 Completed in a time period much less than a second

10. austenite ferrite cementite

11. Bhadeshia, Vitek and David, Materials Science and Technology 7 (1991) 50 austenitic stainlessferritic stainless Physical metallurgy of spot welds in interstitial-free steels

12. Bhadeshia, Vitek and David, Materials Science and Technology 7 (1991) 50

14. UPPER BAINITE (High Temperature) LOWER BAINITE (Low Temperature) Carbon supersaturated plate Carbon diffusion into austenite Carbon diffusion into austenite and carbide precipitation in ferrite Carbide precipitation from austenite

16. Ohmori and Honeycombe

18. Widmanst ä tten ferrite

19. Hayat, Demir, Acarer, Aslanar, Kovove Materialy 47 (2009) 11 Reproduced with permission

20. Bayraktar, Kaplan, Devillers and Chevalier, J. Mat. Proc. Techn. 189 (2007) 114 Reproduced with permission

22. Bhadeshia, Metal Science 16 (1982) 159

24. 1 2 3 4 5 6 1. Fe-0.4C 2. Fe-0.4C-2Si 3. Fe-0.4C-1Ni 4. Fe-0.4C-1Mn 5. Fe-0.4C-1Mn-1Cr 6. 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 Temperature / C calculations

26. Mukhopadhyay, Bhattacharya and Ray, J. Mat. Proc. Techn. 209 (2009) 1995 Reproduced with permission

27. Mukhopadhyay, Bhattacharya and Ray, J. Mat. Proc. Techn. 209 (2009) 1995 Reproduced with permission

28. Mukhopadhyay, Bhattacharya and Ray, J. Mat. Proc. Techn. 209 (2009) 1995 Reproduced with permission

31. Bhadeshia, Svensson & Gretoft, Acta Metallurgica 33 (1985) 1271