Effects of Alloying Element V on Microstructure and Mechanical Properties of Low Alloy CrMo Steel for Power Fittings

The effects of alloying element V on the microstructure and mechanical properties of low-alloy CrMo steel used for power fittings were contrastive by studied by mechanical property testing and microstructure observation. The results show that with the increase of V content, the size of M-A component on the granular bainite gradually increases after annealing. The decomposition degree of M-A component is related to the V content during tempering. The higher the V content, the more insufficient the decomposition of the M-A component, and the more M₂₃C₆ precipitates at the grain boundary. The higher the V content, the more insufficient the decomposition of the M-A component result in an increase in the strength of the material. With the increase of V content, the insufficient dissolution of M-A components, the precipitation and growth of M₂₃C₆ at the grain boundary and in the subcrystal boundary are the main reasons for the decline of the impact toughness of the material.