Process Optimization of a Fe-Based Coating Laser Clad onto a 42CrMo Steel Coal Mine Roller

The coal mine roller is a key component in the mine belt conveyor system. The work described herein involved a Fe-based clad prepared on a 42CrMo steel roller substrate by laser cladding in order to improve the service life and performance of the coal mine roller. The chemical composition, microstructure, properties, microhardness, wear resistance and salt spray corrosion performance of the laser clad layer and substrate under the optimum process parameters were systematically studied. The results showed that laser scanning speed and laser power mainly affect the width, height and depth of the clad. The process parameters were optimized by a series of orthogonal experiments. The optimal process parameters were a laser power of 1700 W, scanning speed of 6 mm/s and powder feed rate of 15 g/min. The laser clad mainly composed gamma-Fe and the compounds of Fe and Cr, such as CrFe4and CrFe19. Along the depth direction of laser clad the microstructure gradually changed from planar crystal and bits of dendrite crystal to equiaxed crystal. The grains at the top of the direction of the laser cladding layer were further refined. The hardness of the laser clad was increased by about 2.2 times that of the substrate. The friction and the loss of weight from wear test and salt spray corrosion of the laser clad show that the weight gain is much smaller than that of the substrate. The experimental results show that the wear resistance and corrosion resistance are improved significantly.