PISTON RING EXCELLENT IN RESISTANCE TO SCUFFING, CRACKING AND FATIGUE AND METHOD FOR PRODUCING THE SAME, AND COMBINATION OF PISTON RING AND CYLINDER BLOCK

摘要

A piston ring comprised of a high chromium martensitic stainless steel having a nitrided layer on the surface thereof, characterized in that the stainless steel has a chemical composition, in wt %: C: 0.3 to 1.0 %, Cr: 14.0 to 21.0, N: 0.05 to 0.50, the total of one or more of Mo, V, W and Nb: 0.03 to 3.0, Si: 0.1 to 1.0 %, Mn: 0.1 to 1.0 %, P: 0.05 % or less, S: 0.05 % or less, and balance: Fe and inevitable impurities, and the sliding nitrided layer has hard particles mainly comprising nitrides which have an average diameter of 0.2 to 2 ñm and a maximum diameter of 7 ñm or less and are dispersed on the surface thereof with an area percentage of 5 to 30 %. The high chromium martensitic stainless steel exhibits improved resistance to scuffing, cracking and fatigue.