Effects of Hot Deformation on γ→α Isothermal Transformation for High Niobium Low Carbon Steel

Using thermal simulation tester,austenite to ferrite isothermal transformation for a low carbon high niobium steel with and without hot deformation was investigated．It was obtained that curves of austenite to ferrite isothermal transformation at 700℃ for the tested steel in un-deformation, deformation 20% and 30% at 875℃,respectively. Influence of hot deformation and niobium on was discussed. The results show that the ferrite transformation is accelerated by hot deformation，because incubation period of the transformation is shortened by hot deformation，and the kinetics of austenite to ferrite isothermal transformation for high niobium steel is two stage that is ferrite transformation rate is lower in the first period and is higher in the second.