Continuous cooling transformation of 600 MPa grade low carbon bainite steel produced by CSP process

The static and dynamic CCT curves of low carbon bainite steel microalloyed with Nb, V, Ti, Mo and Cr were tested with a Formaster-Digital dilatometer and a Gleeble-1500 thermo-mechanical simulator, respectively. The transformation microstructures were observed by SEM and TEM. It is shown that the transformation microstructures are bainite after continuous cooling when the cooling rate is more than 10℃·s^-1 due to the fact that alloy additions inhibit the transformation from austenite to ferrite, which results in excellent strength; in addition, deformation promotes bainite transformation, and the start temperature and final temperature of bainite transformation are 610 to 668℃ and 520 to 551℃, respectively.