Effect of laser scanning rate on microstructure and wear resistance of SLM high speed steel layer

Based on the fretting wear failure of key parts of short stress line rolling mill, selective laser melting was chosen to repair the failure parts. The effect of laser scanning rate on microstructure, hardness and wear resistance of cladding layer was studied. The results show that the microstructure of the cladding layer is mainly lamellar martensite with a little retained austenite and carbide. The hardness of the cladding layer increases with the increase of scanning rate and the decrease of energy density. The maximum hardness is about 950 HV0.2. The friction coefficient of the cladding layer varies little with different laser scanning rate. The wear rate of the cladding layer increases firstly and then decreases with the increase of laser scanning rate. The wear rate of the sample with scanning rate of 6 mm/s is the smallest, which is 2.0466•10-5 mm3/(N·m) .