Effect of laser remelting on internal defects and properties of Ni-based coatings reinforced by multi-channel WC in situ

In order to investigate the effect of laser remelting on the properties of hot work die steel, WC reinforced Ni base remelting layer was prepared on H13 steel surface. Optical metallography microscope, X-ray diffractometer and scanning electron microscope were used to analyze the macroscopic defects, phase evolution and microstructure of the coating before and after laser remelting. Microhardness tester and friction and wear tester were used to test the microhardness and wear resistance of the remelted layer, and compared with the coating without remelting. The results show that the inner porosity of the coating decreases with the increase of laser power. With the dissolution of WC/W2C ceramic particles and the uniform distribution of W element, the distribution of reinforcement particles in the coating becomes more and more uniform. When the laser power reaches 1500 W, the WC/W2C ceramic particles inside the coating basically disappear, the porosity is reduced to the lowest, the coating uniformity is the best, and the microhardness and wear resistance are the highest.