Producing superfine low-carbon bainitic structure through a new combined thermo-mechanical process

Recently, many steel researchers have been attempting to develop superfine low-carbon bainitic microstructure; however, the results are not satisfactory. In this paper, we applied a new thermo-mechanical process for achieving low-carbon superfine bainitic structure. By applying the new process, i.e. ausforming at temperatures above Ms followed by austempering at 355 °C, which is below Ms, we successfully obtained a superfine, ladder-like bainitic structure, with bainitic laths as thin as ∼100 nm and Vickers hardness as high as ∼500 HV, being of the same level of medium-carbon bainitic steels. This new process shows a potential for wide industrial applications.