Influence of friction-induced retained austenite transformation to martensite on the wear properties of a carburized layer of 23CrNi3MoA steel

This paper investigates the effect of the friction-induced retained austenite (RA) transformation to martensite on the surface wear performance of steel. 23CrNi3MoA steel was subjected to different carburizing processes to explore the effects of the RA volume fraction, carbon content and size on the stability of the metal. The results show that RA size is the key to controlling the mechanical stability of austenite in friction experiments. When the RA content is 20%–30%, the RA is small and has a uniform distribution and high mechanical stability. A small amount of friction-induced martensite is present in nanosheet form, and the particle size of the wear-stripped martensite is small, thereby reducing the amount of wear. When the content of RA is 30%–50%, the size of the RA is coarse, its distribution is uneven, the mechanical stability of the steel is low, the size of the exfoliated particles is coarse, and the wear performance of the steel is reduced. Through microstructural characterization of the worn surface, subsurface and matrix, it was found that cracks formed at the interface of the transformation induced martensite and the RA of the matrix during wear and penetrated the entire transformation induced martensite along the longitudinal direction of the interface. The bulk layer even extends into the deep matrix, thus eventually forming large exfoliations. The wear mechanism of RA during dry sliding friction is clarified, and a basis for the reasonable control of RA during production is provided.