MICROSTRUCTURAL EVALUATION OF SALT NITROCARBURIZING AS FUNCTION OF TIME

A set of H13 steels were studied with the aim of improving their performance. Austenitzed in a vacuum furnace at 1015°C for 180 minutes and quenched with nitrogen (2 bar) followed by two temperings at 540°C and 560°C for a period of 3 hours each. The nitrocraburizing process was performed in liquid salt bath at 570°C for 45, 60, 90, 120, 150 and 180 minutes in order to evaluate the effect of time in the nitrocarburizing layer. After the quenching and tempering treatments, the steels exhibited a 52 to 54 HRc and a surface hardness of 950 to 1100 HV with a nitrocraburizing layer  of 20 microns. Microstructural evolution of the compound and diffusion layers were studied by scanning electron microscopy and by X-ray diffraction analysis. From microstructural characterization, it was observed a continuous nitrocraburizing e/g´ layer with nitrocraburizing times between 45 and 60 minutes and also better wear performance.