The effect of heat treatment temperature on the wear resistance of 42CrMo steel hardfacing with Fe–Cr–C alloy

Fe–Cr–C hardfacing alloys are widely used in hardfacing applications because of their high strength. In this study, a Fe–Cr–C hardfacing layer was deposited on a 42CrMo steel plate by manual arc welding. The effects of post-weld heat treatment at 400 ℃, 600 ℃, and 800 ℃ on residual stress in the hardfaced layer were examined by finite element simulation. The simulation results showed that heat treatment at 600 ℃ effectively reduced the residual stress. Optical microscopy, X-ray diffraction, energy-dispersive spectroscopy, microhardness, wear testing and scanning electron microscope were then used to evaluate how heat treatment influences the microstructure and wear behavior of the hardfacing alloy. After hardfacing, a dendritic structure formed at the weld interface. Following heat treatment at 600 ℃, carbides diffused along grain boundaries into the ferrite matrix, and the dendritic structure transformed into a carbide-rich dendritic morphology. After heat treatment at 600 °C, the hardness of the hardfacing alloy increased to 551.3 HV, the friction coefficient rose to 1.17, and the volume wear loss decreased by 26.1%. The wear mechanism of the hardfacing alloy was dominated by abrasive wear. These results indicate that, for 42CrMo steel hardfaced with a Fe–Cr–C alloy, selecting an appropriate heat treatment temperature can not only relieve residual stress but also enhance the wear resistance of the material.