The depth of the diffusion of nitrogen in 16MnCr5 steel after gas nitriding

Abstract

This research aims to determine the depth of diffusion of nitrogen in steel 16MnCr5 after gas nitriding. Nitriding was performed in the ammonia atmosphere at three temperatures (510, 550 and 590°C), with four different durations for each temperature. The research techniques were metallographic and electron probe micro-analysis (EPMA). According to the first method, with the optical microscope Neophot 30 of the firm Carl Zeiss Jena, the surfaces of all samples were observed. The nitriding layers were photographed with the help of a microscope, from which the depths of nitrogen diffusion were determined. The hardness-depth profiles of nitride specimens were determined with a Vickers automatic micro-hardness tester from LECO, and the distance between two consecutive points was 50 μm. The depth of nitrogen diffusion into the nitride samples was determined from the hardness curves. The nitrogen concentration-depth profiles of the nitrided specimens were determined with EPMA using a Joel JXA-8900RL microanalyser operated at 20 kV. A comparison of the results of the different experimental methods was made, which allowed conclusions to be made as regards the depth of nitrogen diffusion in 16MnCr5 steel.