The Structure and Mechanical Properties of Cr4Mo4V Steel Treated by PⅢ Carbonitriding

摘要

The composition and structure of PHI (plasma immersion ion implantation) carbonitrided Cr4Mo4V steel were analyzed using X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), optical microscopy (OM) and SEM. The results indicate that the nitride and carbide are dispersion phase precipitation and except formation of compound other implantation atoms dissolve into martensite matrix. The total concentration of carbon and nitrogen is about 30 at% near the surface, and still keeps at about 20 at% even at the depth of 8 μm. The effect of treatment temperature, implantation time and ratio of N2 to CH4 on the hardness and wear resistance of carbonitrided layer are investigated. It is found that the hardness of Cr4Mo4V steel increases after treatment. The highest hardness of samples is 22.3 GPa, which is about 1.8 times than initial steel. The dry-wear resistance of the samples is also improved after treatment, and the sample with higher hardness shows the better wear resistance.