NITRIDED PISTON RING RESISTANT TO CRACK PROPAGATION

摘要

The present invention addresses the problem of how to prevent the nitrided layer on piston rings for flex-fuel engines from becoming detached, without affecting wear resistance. For that purpose, a nitrided piston ring (100, 100') is provided with two nitrided layers (1, 2) and a metallic base (3) mainly composed of iron, the surface hardness of which is of about 800 Vickers and decreases in a substantially linear manner down to 400 Vickers at a distance from the surface of up to 90 micrometres (µm).