Effect of vacuum carburizing on surface properties and microstructure of a tungsten heavy alloy

Abstract

Vacuum carburizing of the R2M tungsten alloy was carried out to obtain a carburized layer that improves the surface properties. The effects of various carburizing temperatures and times on the structure and hardness were studied by Optical microscopy(OM), x-ray Diffraction(XRD) and Scanning electron microscope(SEM). In this work, the microstructure of the carburized layer, the relative content of the surface layer, the depth of the layer and the microhardness of the carburized sample were studied. The results show that the microstructure exhibited three layers from the surface to the bulk of the sample after carburizing. The outside layer comprised a 40 ∼ 60 μm deep WC carburized layer. The hardness of the surface layer (396 HV) was significantly higher than that of the substrate (282 HV). As the carburizing temperature and time increased, the WC and W content of the surface layer of the sample gradually increased, and the depth of the carburized outer layer increased.