| Prashant, In a nutshell: The basic difference is in carrying out the initial rolling operation at temp above Ac3 and below it in a controlled manner, then rapid cooling it to a little above Ac1 - ~10°C/sec. This refines austenite (austenite-ferrite) and renders it equi-axed..At a temp slightly above Ac1, the controlled rolling is stopped to introduce rapid cooling to an intermediate temp or even ambient temp as required. Fine ferrite + pearlite is the normal microstructure though you can have tougher and stronger bainite - all depends on deformation temp and strain rate. TMCP steels are much more superior in strength (also in toughness) as compared to the conventional steels of same composition and physical material content (weight). Even better than normalized steels in the same aspects. Optimum grain refinement and phase dispersion is obtained when the controlled finish rolling temperature is around 700-800°C. These steel plates are now extensively used in marine sub zero temp applications - lessons learned from Titanic disaster had a lot to contribute to their development.Please see attached a schematic comparison chart between conventional and TMCP process. I could not place it here. Regards, Shashank Vagal --- On Tue, 14/9/10, prashant pansare <prashantpan_99@yahoo.co.in> wrote:
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