Ferrite formation from deformed austenite in Nb-V and Nb-V-Ti microalloyed steels

A study of the grain coarsening characteristics in C-Mn, Nb-V and Nb-V-Ti steels has shown that the grain coarsening occurs at a low temperature (< 950®C) in the cast C-Mn steel. This seems due to the low solution temperature of the AIN grain boundary pinning particles. However, the grain coarsening temperature ( GCT) can be increased by microalloy additions for Nb-V and Nb-V-Ti steels. Ferrite formation from deformed austenite has been investigated in C-Mn, Nb-V and Nb-V-Ti steels after single pass hot rolling. Rolling reductions were given in the range 20%-60% in temperature range 850°C - 1050°C and the deformed samples were transformed isothermally to ferrite at 680*'C for up to 1800 sec.