The effect of composition and heat treatment (solutionizing at 1200 degrees C and aging at 750 degrees C) on the room temperature mechanical properties (hardness and impact toughness) and dry sliding wear resistance of Fe-0.4C-25Cr-XNi steels (where nominal Ni contents were 4, 12 and 20 wt.%) have been investigated. The steel containing 4 wt.% Ni had ferritic and others (12 and 20 wt.% Ni) had austenitic matrixes along with M23C6 type chromium carbides. The applied heat treatment resulted in precipitation of sigma phase in austenitic matrix, which was accompanied by an improvement in hardness and a decrease in impact toughness. Ferritic matrix steel exhibited higher hardness and lower impact toughness than austenitic matrix steels. The results of the wear tests conducted on an unlubricated M2 quality tool steel disc revealed that at test pressures lower than 2.2 N/mm(2), the dominant wear mechanism was mild wear. However, at high test pressures (> 2.2 N/mm(2)) severe wear mechanism was operative. Increase of hardness and decrease of toughness resulted in a decrease in wear resistance under mild wear conditions. However, these mechanical properties were not effective on wear resistance under severe wear testing conditions. (c) 2005 Elsevier B.V. All rights reserved.