Wear of nano-structured carbide-free bainitic steels under dry rolling–sliding conditions

Specially designed steels with carbon contents from 0.6 to 1.0 wt% were isothermally transformed at very low temperatures, between 220 and 270 °C, in order to obtain a nano-structured bainitic microstructure. It is shown that the wear resistance in dry rolling–sliding of these nano-structured steels is significantly superior to that of bainitic steels transformed at higher temperatures with similar hardness values. In addition to the highly refined microstructure, the transformation under strain to martensite (TRIP effect), contributes to the plasticity of the nano-scaled steels, increasing surface hardness during testing, thus reducing the wear rate.

► High-Si steels were austempered yielding nano-scaled bainitic ferrite/austenite microstructure.
► Nanobainitic steels were compared with reference steels using dry rolling–sliding tests.
► At similar hardness, the nanobainitic steels presented an improvement in wear resistance.
► Rolling contact fatigue and adhesion were the main mechanisms of material removal.
► The TRIP effect can have a high influence on wear resistance.