Enhanced toughness of bearing steel by combining prior cold deformation with martensite pre-quenching and bainite transformation

This work reasonably utilizes the decreasing of martensite start (Ms) temperature caused by prior cold deformation, combining martensite pre-quenching and bainite transformation to develop ultrafine martensite-bainite duplex microstructures for improves toughness of GCr15 bearing steel. Comparison with the conventional quenched and tempered (QT) specimen, the remarkable improvement of impact toughness (similar to 87 J) and fracture toughness (similar to 39 MPa.m(1/2)) were achieved in 30% prior cold deformed specimen, while with a slight decrease in the hardness. The enhanced toughness was attributed to the nanometric martensite-bainite duplex microstructures and the formation of film-like retained austenite. (C) 2018 Elsevier B.V. All rights reserved.