Wear resistance behavior between gaseous carburising followed by salt bat nitriding and gaseous nitrocarburising of microalloyed steels

Full text.The effect of salt bath nitriding and nitrocarburising on the microstructure, and the microhardness and the wear resistance of microalloyed steels was investigated. The wear tests were carried out on the specimens nitrocarburised in the ambient atmosphere and the results are compared with those of the nitrided specimens. Nitrocarburising and nitriding process have been carried out respectively at 1203 degreK for 5h in CH4/ NH3 atmosphere and 853 degreK for 7h. The heat treatment applied after the nitrocarburising process and which consists to an quenching and tempering induces in the near surface, one composed structure of martensite and the very fine precipitation of nitrides and carbonitrides. However, this structural state improves the microhardness profile and the wear resistance. It was found that the weight loss of nitrocarburised samples is more less pronounced than that the nitrided samples. The microstructures of the nitrided and nitrocarburised cases and worn surface topographies were observed by optical microscope and scanning electron microscope (SEM. The phases structures formed since the near surface to the substrat were determined by x-ray diffraction (XRD) using Cu Kα radiation