Effects of Vacuum Annealing on Microstructure and Properties of Nitriding Layer of 1Cr11Ni2W2MoV Steel

In view of obvious hardness difference between the heart and the surface of aviation stainless steel, which is easy to cause the peeling of the parts, the vacuum annealing process was adopted to form the nitrogen and carbon co-seepage diffusion layer to enhance the toughness of the part surface and significantly improve the sample quality. The microstructure,properties and surface quality of 1Cr11Ni2W2MoV steel were observed and analyzed by means of metallographic microscope,microhardness tester and laser confocal microscope. The element distribution characteristics in the direction from the surface layer to the core were determined by electron probe analysis. The results show that a compound layer of 18 μm thickness can be formed between the infiltrated layer and the substrate, and the vacuum annealing treatment makes the distribution gradient of N and C elements more gentle and reduces the hardness difference between the surface layer and the substrate. Annealing treatment at 590℃ for 90 min of 1Cr11Ni2W2MoV steel can make the permeability transition more uniform, mircrostructure stability and surface quality better, which plays the role of reducing embrittlement and toughness.