Study of the Surface Nanocrystallization Pulse Plasma Nitriding at 360

Plasma nitriding of surface nanocrystallized 3J33 maraging steel at 360 ℃ for different time was studied.Microhardness test shows that the thickness of nitriding layer is up to 50 μm when nitriding at 360 ℃ for 8 h and the surface hardness is about 800 HV0.05.But nitriding layer is not growing remarkably with prolonging nitriding time after 8 h;The XRD results indicate that the nitriding layer is not composed of Fe4N and Fe3N,but low nitrogen nitride FeN0.0324;Nano-indentation test shows that the hardness of the nitrided layer is about 13 GPa,which is about 3 times higher than that of the original one.