INFLUENCE OF THE LAYER THICKNESS OF THE S PHASE ON THE ABRASIVE WEAR RESISTANCE OF PLASMA-NITRIDED AISI 316L AUSTENITIC STAINLESS STEEL

摘要

Pulsed DC plasma nitriding experiments performed under a treatment atmosphere of 75%N2 + 25%H2, at a temperature of 430 °C and for nitriding times from 2 h to 8 h allowed the formation of nitrided layers of different thicknesses on AISI 316L stainless steel. The results indicated that all of the nitrided layers were composed of the S-phase with thicknesses ranging from 1.7 to 9.3 μm, exhibiting a wear resistance greater than that of the untreated steel. The wear resistance of the material continuously increases with the thickening of the S-phase layer; however, a decreasing in the wear resistance associated with the S-phase decomposition was noted for layers with thicknesses greater than 3.0 μm. Three-body wear rolling is the dominant wear mechanism for both the untreated and the nitrided steel despite the significant differences between their wear resistances.