Laser Remanufacturing Research And Failure Analysis Of Aluminum Wheel Hub Mold

With the improvement of economic level and quality of life,people tend to concern the problems such as environmental pollution and ecological destruction and so on; As the use of automobiles increases year by year, people began to seek ways of reducing car weight for the purpose of energy saving, in which is the reducing of the wheel weight.As alloy wheel hub has such advantages below: beautiful appearance, strong corrosion resistance, good processability, light weight, high specific strength, good heat dissipation and energy saving, it can satisfy the basic requirement of automobile lightweight, and becomes one of the best choices for insteading of steel material as automobile wheel hub. Because the H13 steel has high hardenability, high toughness, excellent processability, good wear resistance and thermal crack resistance, as well as fine ability to resist decarburization, it’s widely used in aluminum alloy die casting mould. But the bad working environment of the aluminum alloy die-casting mold lead to various forms of failure in mold, including the thermal fatigue crack, thermal damage and erosion, bonding, fracture, mould cavity deformation and so on.In this paper, by the method of laser cladding remanufacturing, and with the combination of the remanufacture theory and practice, the actual application environment of aluminium alloy wheel hub mould, the characteristics of aluminum alloy die casting and main failure form are studied. The germination and growth of thermal fatigue crack, the main failure part of hot melt loss effect are systematically analyzed, and the bond strength is tested, etc.; meanwhile, the mechanism of the main failure forms are researched.The zonal segregation and the composition and distribution rule of intergranular carbide alloy in annealing state organization of H13 steel were analyzed and evaluated, as well as it’s grade evaluation was researched. The differences of residual carbon, including the content, morphology, regularities of distribution, in the H13 steel organization after different heat treatment process was studied.The best process route of laser cladding and the suitable alloy powder are determined in the remanufacture of Aluminum alloy wheel hub mould, which based on the actual application environment, the main failure modes, as well as the physical properties of the H13 steel itself. Stellite12 high temperature alloy is selected as Cladding material. The test from single laser cladding to multi-layer laser cladding was studied on the H13 steel substrate, respectively; meanwhile,making the contrast analysis of the microscopic structure and mechanical performance. The crack initiation and extension methods in the Cladding layer are systematically researched, and then the mechanism of cracking was studied. The difference in the microstructure of Cladding layer and substrate materials, with the change of temperature rising trend, was studied; as well as the reinforcement mechanism of cladding layer was discussed.laser cladding cobalt-based alloy consists of a large amount of white γ-Co dendrite, intercrystalline eutectic organization and diffuse distribution of the secondary precipitation phase composition. This improved hardness of the clad zone is attributed to the presence of high hardness,high melting point,hard strengthening carbides phase in the microstructure and fine-grain strengthening effect.