H11 steel discs were tested by considering sliding/rolling friction under dry and lubricated conditions. The H11 discs were plasma nitrided at 500 degrees C and 550 degrees C for 9 h. Wear tests were conducted at different slip ratios of 1.79%, 10.53% and 22.22%. The test loads were 100 N, 150 N and 200 N. It was determined that plasma-nitrided H11 discs had a surface hardness of 1200-1400 HV0.1. Plasma nitriding produced wear performance much higher than those of the un-nitrided but hardened samples. The wear mechanism of the plasma-nitrided discs was a mixture of adhesive wear, abrasive wear and plastic yielding. (C) 2012 Elsevier Ltd. All rights reserved.