Effect of prior warm rolling on the retained austenite content and hardening response of (VIM-VAR)--AISI M-50 steel

Abstract

The objective of warm rolling M-50 bearing steel is microstructural refinement which may lead to increases in rolling contact fatigue life. A consequence of this final hardening is that the austenitizing temperature used in the final hardening cycle should be reduced. This is because warm rolling leads to faster dissolution of finer soluble carbides at the austenitizing temperature. This thesis effort determined the temperature decrease that warm rolling allows in austenitizing to produce a microstructure of finer grain and carbide size but equivalent carbide dissolution. Here, this has been inferred by measurement of the volume fraction of retained austenite in the as-hardened microstructure, retained austenite being a function of the amount of carbides taken into solution during austenitization. It was found that the standard austenitizing temperature of 110 degrees C used to harden stock M-50 can be reduced by 63 Centigrade degrees with warm-rolled M050 steel.