Study on pressurized gas nitriding characteristics for steel 38CrMoAlA

Abstract

The effects of nitriding pressure on the microstructure, surface hardness, thickness and wear resistance of the nitrided layer on 38CrMoAlA steel were investigated. Gas nitriding was conducted in flowing NH3 gas at 510°C for 5h under nitriding pressures ranging from 1 to 6atm. The results show that, compared with conventional gas nitriding (1atm), the increase in nitriding pressure markedly accelerated the gas nitriding kinetic process and promoted the rapid thickening of the nitrided layers. Both the microstructure and the microhardness of the nitrided surface layer were strictly controlled by nitriding pressure. The nitrided layer of the sample nitrided under 6atm for 5h exhibited the best wear resistance, and its thickness (410μm) was almost equal to that (440μm) of the conventional gas nitriding at 510°C for 50h, which would result in higher production efficiency and lower cost in industrial application.