AbstractA successive grinding technique was used to examine the changes in microstructure generated by fretting of a 1C–1·5 Cr steel. The findings indicated that the white phase was precipitation hardened austenite and that it grew laterally by coalescence of initial areas of a few micrometres. Frequently, very small modifications of the initial microstructure were found near the white phase. This is explained by the small quantity of heat generated and its rapid dissipation in the steel. Similar carbide precipitates to those in the white phase were found in areas of residual austenite in rapidly solidified water atomised particles of the same type of steel.MST/3151