Retained austenite stabilisation in low carbon high silicon steel during isothermal holding

Abstract

We elucidate here the role of isothermal hold temperature of 300–500°C after intercritical annealing at 760°C on bainitic transformation and in governing the stabilisation of retained austenite in a 0.23C-1.35Si-1.82Mn steel. A critical analysis was attempted to explain the observations using displacive mechanism of bainite formation in the attempt to endeavour to understand the kinetics of bainitic transformation during isothermal holding. The model predicted that carbon enrichment in austenite was of particular significance in governing the stability of retained austenite. Thus, through the contribution of transformation induced plasticity effect of retained austenite, high tensile strength (964 MPa) and excellent ductility (uniform elongation of 24.5% and total elongation of 32%) was obtained on isothermal holding at 400°C.