The Research On Laser Cladding And Welding Of 6061 Aluminum Alloy For High-speed Trains

6061 aluminum alloy is a typical medium-strength aluminum alloy. Because of its excellent weld and corrosion-resistant properties, 6061 aluminum alloy has been one of the leading materials for high-speed vehicle manufacturing.Compared with conventional welding technology, laser welding aluminum alloy has the advantages of high energy density, high speed, small welding deformation, etc.But there are defects such as porosity and surface collapse in laser welding. To eliminate defects, two aspects have been studied: one is the effect of shielding gas on laser welding of 6061 aluminum alloy; the other is the effect of laser cladding power on laser welding of 6061 aluminum alloy.The gas protection device was designed. The influence of the back shielding gas flow rate, types and flow rate of side-blowing gas on the weld formation were investigated. The results show that the optimizing welding parameters are the back protection gas flow 14 L/min, selection 99.999%Ar as side blow protection gas and blow gas flow 8~14 L/min; the crystal of weld joints is tiny. The weld has a minimum hardness of 65 HV, a tensile strength of the joints reaching 253.62 MPa..In order to eliminate that collapse, the combination of laser cladding and laser welding was used. The influence of different types of powders on laser welding of6061 aluminum alloy was researched. The results show that uniform structure is formed and the weld is higher after cladding Al powder. The amount of reinforcement phase significantly increases after cladding Si powder. A good weld without collapse is formed after cladding Ni powder. Porosity increases after cladding Ti powder. After cladding Al-Si powder, more reinforcement phase and smaller grains are formed. After cladding Al-Ni powder, the weld has smaller grains and higher hardness.Al-Si-Ni powders were mixed as cladding preset powder. Optimization of the formula of the powder was employed by using mixture design. The research results show that the optimal composition of the mixed powder isAl:Si:Ni=0.737:0.185:0.078. The grains of weld joints are tiny and the micro-hardness of the weld is uniform. The joints reaching 230.01 MPa...