Piston ring and process for manufacturing the same

摘要

The object of the present invention is to provide a piston ring which is free from occurrence of cracks on the nitrided layer and having enhanced abrasion resistance and fatigue strength, and to provide a process for manufacturing the piston ring. In the invention, a surface of the steel body is subjected to a two-stage nitriding treatment consisting of low-temperature nitriding and high-temperature nitriding. A white layer on the slidable surface along the inner periphery surface of a cylinder is removed, and a white layer on each of the upper and lower surfaces and the corner portions each being adjacent to the slidable surface is removed to have a thickness of not more than 5 (my)m.