Research On Repairing Cold Mold With Concave Surface By Laser Cladding

Due to the constant friction with the material being processed, the cold mold can bear great pressure or impact. As the cold mold is easy to be damaged, so it need to be repaired. Laser cladding is a new surface repair technology. It has a small heat affected zone and a low dilution rate. What’s more, it is easy to be realize automation. It has great economic value and theoretical significance to apply the technology on the repair of mold with complex curved surface.For the process parameters of laser cladding Ni-based powder on Cr12 cold mold steel, single factor and single channel orthogonal experiments were carried out in turn. The suitable process parameters of the experiments are laser power is 1500 W, scanning speed is 2 mm/s, rotational speed is 10 r/min, carrier gas is 6 L/min, and the amount of out of focus is +2 mm.In order to solve the problem of cracking of Ni-based powder laser cladding layer, ANSYS was applied to the temperature field simulation of the multi-channel cladding layer to analysis the temperature field and stress field. Multi-channel cladding experiments and multi-layer cladding experiments were carried out to get better lap ratio and process parameters. The results show that: when the lap ratio is 1/2, the laser power in the first layer is 1 300 W and the laser power in the second layer is 1 300 W the laser cladding layers are the best.Path planning experiments were carried out on the Cr12 cold mold steel with concave surface to get the laser cladding forming parameters on concave curved surface. The scanning path of reciprocating motion from low to high is the best in single channel repair experiments. And the cladding surface which the starting points of the first layer and the second layer has offset of 1.5 mm is more smooth.The microstructure, hardness testing and friction and wear test of Ni-based powder laser cladding repair layer were studied. The microstructure investigation shows that the cladding layer and substrate has realized the metallurgical combination, and the microstructure of the cladding layer is dense dendrite. The hardness of the cladding layer is from 390 HV to 540 HV, and the wear resistant properties of cladding layer is similar to the substrate, the wear amount of the cladding layer is 23.33 mg, and the substrate is 21.66 mg.