Effect of warm rolling process on phase transformation, microstructure and mechanical properties of nano-bainite steel

Nanostructured bainite steel with an ultimate tensile strength of 2127 MPa, elongation of 4% has been obtained by warm rolling followed with isothermal heat treatment. The effect of deformation temperature on transformation of nano bainites has been investigated. The results show that with a proper warm defromation, the time required for the transformation of the supercooled austenite into bainite can be shortened from 50 h to 20 h. The deformation rates of supercooled austenite adopted at all temperatures in the experiments can accelerate the low temperature nanobainite transformation, while the transformation rate increased with the decreasing deformation temperature. With a deformation rate above 30%, the retained austenites were sharply refined and the blocky austenites were diminished. The low temperature nano bainite transformation can be accelerated by warm rolling process without harm to the strength, thus shortening the time of heat treatment resulting in cost saving of the steel production. © Copyright.