Extreme High Speed Laser Cladding 316L Coating

Abstract

Using extreme high speed laser cladding technology, 316L coating was prepared on 45 steel shaft. The microstructure of the coating was observed by scanning electron microscope (SEM), and the wear resistance and corrosion resistance of the coating were tested. The results show that the coating prepared by the extreme high speed laser cladding technology has high surface flatness, no obvious cracks, voids and other defects, high density, good combination with the substrate, and fine grains. The middle and lower crystal grains are dendritic, which grows perpendicularly to the surface preferentially, and no obvious secondary dendrites are seen. The size of the dendrites in the lower part of the coating gradually decreases from the bottom to the top of the molten pool, and the top layer transforms to equiaxed grains. The dilution rate is 4.4%. The fine-grain strengthening mechanism improves the wear resistance of the coating, and the wear resistance is increased by about 31.8%. The wear mechanism is mainly abrasive wear. A stable chromium-rich oxide film is formed on the surface of the coating, and its corrosion resistance is greatly improved, but this film will be destroyed by highly concentration of Cl-.