Research Of 7A52 Aluminum Alloy MIG Welding Mechanical Properties And Corrosion Behavior

Research purpose:Aluminum alloy has become the first choice of lightweight structural materials with high strength to weight ratio and stable performance.Arc welding has been in an irreplaceable position in the field of emergency maintenance,in terms of economy,efficiency and flexibility.MIG welding repair method is widely used in arc welding.Light weight welding equipment is often attacked by acid rain environment,especially in welded joints with uneven composition.The mechanism of corrosion behavior of aluminum alloy welded joints is still controversial.Method:The welding process parameters of aluminum alloy MIG welding were optimized by tensile test,4mm thickness 7A52 aluminum alloy plate in this paper.The corrosion behavior tendency of the welded joint was tested with 10ml/L HCl+30g/L NaCl experimental condition instead of acid rain.The stress field of welded joints was simulated and verified.The mechanism of corrosion was revealed by stress distribution.The main conclusions are as follows:(1)the best welding parameters of 7A52 aluminum alloy welded structure are: welding current 180 A,welding speed 40cm/min.The average tensile strength can reach 312.4MPa and coefficient of welding joint is 66.5%.(2)The bestcorrosion resistance of the joints is characterized by the following parameters: the weld is-0.612 V,the heat affected zone is-0.540 V,the matrix is-0.528 V.(3)The morphology analysis shows that the corrosion resistance of the weld is better than that of the matrix,and the corrosion tendency of the welding seam is higher than that of the matrix.The two contradiction is due to the effect of the residual stress field of the welded joint.The tensile stress zone is formed in the center of the weld and the matrix is the compressive stress zone.The corrosion tendency of welded joint of aluminum alloy is related to the stress field existing in the joint.The biggertensile stress causes the bigger corrosion tendency.The bigger the compressive stress causes the smaller the corrosion tendency.