How different steel grades react to a low pressure nitriding process: influence of alloying elements
A sensor is placed inside an industrial furnace to regulate the nitriding potential during a low pressure nitriding gaseous treatment at 300 mbar. This accurate control of the KN allows to compare metallurgical results between two different steel grades (42CrMo4 and 32CrMoV13) but also between this process and conventional ones at atmospheric pressure. XRD patterns were realised to control the phases present on the surface, some micro-hardness profiles are presented to measure the diffusion layers and micrographies were done to check the thickness of combination layers. Three different cycles are proposed, KN=0,2, KN=0,3 and KN=2 to see the evolution of the microstructure with the nitriding potential. The analysis of diffusion layers shows that this process seems faster than nitriding at atmospheric pressure and the thickness of combination layers strongly depend on the alloying elements.
Keywords: low-pressure nitriding; sensor; 42CrMo4; 32CrMoV13; XRD; nitriding potential.