Wear behavior of nanostructured carbo-austempered cast steels under rolling-sliding conditions

Carbo-austempered steels with a nanobainitic microstructure in the case are established as an exciting alternative in applications demanding high stability and reliability against wear and fatigue. In this work, the effect of heat treatment conditions, i.e. austenitizing and isothermal transformation temperatures, on the wear behavior under rolling/sliding conditions of a carburized cast steel with a nanobainitic structure in the surface was examined. The results show that wear damage is mainly due to contact fatigue, with a small extent of oxidative wear, abrasion and adhesion. The results were compared with the conventional tempered martensite plus retained austenite microstructure obtained by means of carburizing followed by quenching and tempering. The nanobainitic microstructures show a better wear resistance than the quenched and tempered microstructures. Also, the specific wear rate in carbo-austempered steels was lower as the isothermal heat treatment temperature decreased. Results are explained in terms of the microstructural differences, hardening behavior and plasticity of the materials under study.The authors want to thank the CODI-Universidad de Antioquia for the financial support for the development of this research through the project PRG2017-15869, the National Center for Metallurgical Research - CENIM - and the Tribology and Surfaces Laboratory at the Universidad Nacional de Colombia, Medellin, for the support provided for the experimental development of this work