Effects of hot deformation and subsequent austempering on mechanical properties of high silicon and low silicon TRIP steel

In the present paper, effects of hot deformation and subsequent austempering on the mechanical properties of high silicon and low silicon transformation induced plasticity (TRIP) steel were investigated. The results have shown that polygonal ferrite, granular bainite and a large amount of stabilised retained austenite can be obtained by thermomechanical processing (TMP). Mechanical properties increase with increasing finish rolling reduction and decreasing finish rolling temperature because of the stabilisation of retained austenite. The tensile strength and the total elongation of both steels reach the maximum (791, 794 MPa and 36, 37% respectively). Isothermal holding for 20 min at 400°C after hot deformation is the optimal process. Low silicon TRIP steel shows a larger uniform elongation owing to a stable n value, and it exhibits better mechanical properties than conventional high silicon TRIP steel.