Friction-induced phase transformations and evolution of microstructure of austenitic stainless steel observed by operando synchrotron X-ray diffraction

•The γ−α′ transformation in austenitic stainless steel under dry sliding was studied.•The decomposition of austenite occurs via the formation of intermediate ε-martensite.•The surface layer after the friction consists entirely of α′-martensite.•The main mechanism of wear is the delamination of the mechanically-mixed layer.