Characterisation of Hot-work Tool Steel Treated by a Combined Nitriding and Oxidation Process

摘要

A process that combines gas nitriding and oxidation was used to treat hot-work tool steels by using a pit-type multipurpose furnace. Various properties of the specimen treated by the combined process were investigated and compared to those of an untreated specimen, a nitrided specimen and an oxidised specimen. X-ray diffraction (XRD) analysis of the surface of treated specimen revealed the presence of Fe_3O_4, CrO, Fe_(2-3)N, Fe_4N and CrN. In addition, Cr and O were concentrated in the upper oxide layer of the specimen. Although the surface hardness of the treated specimen was lower than that of the nitrided specimen, the treated specimen exhibited excellent tribological properties, as well as superior soldering and erosion resistance in a molten aluminium die-casting alloy, compared to other specimens.