Effects of Laser Scanning Speed on Microstructure and Wear Resistance of Inconel 718 Coatings

IN718 coatings with the scanning speeds of 6 mm/s, 10 mm/s, 14 mm/s and 18 mm/s were successfully fabricated by coaxial powder feeding laser cladding. The macro morphology, microstructure and composition of IN718coating at four scanning speeds were studied, and the effects of four scanning speeds on the microhardness and friction and wear properties of IN718 coating were analyzed. The results show that when the scanning speed is 14 mm/s, the macro forming quality of the coating is best, and the thickness of the cladding layer is uniform. With the increase of laser scanning speed, the energy density of laser line scanning decreases and the geometry size of molten pool decreases. The microstructure of the cladding layer at each scanning speed is mainly composed of cellular crystal, columnar dendrite and equiaxed crystal.When the scanning speed is 14 mm/s, the cladding layer has more compact grains and smaller size, and the cladding layer is closely bonded with the substrate, without slag, micro cracks and other defects. With the increase of scanning speed, the wear rate of the cladding layer first decreases and then increases. When the scanning speed is 14 mm/s, the lowest wear rate of the cladding layer is 0.02114 mg/m.