Research on MIG welding process and performance of thick plate 5083 aluminum alloy
This research is aimed at MIG welding of 25 mm marine 5083 thick plate aluminum alloy.The welding is difficult,the joint performance is not up to standard,and there are problems of incomplete fusion,incomplete penetration and a large number of pores.After analyzing the macroscopic fracture,mechanical properties and macroscopic metallurgy of the welded joint,we study the effects on improving the process of measures such as grinding and preheating to 150 ℃ before welding,carrying out symmetrical welding,using high-purity shielding gas,and increasing the welding current of backing welding to 170～180 A,the welding current between layers to 210-230 A,the groove to 90°,and the number of welding passes to 27-28.After the improvement of the process,through non-destructive testing,stretching,bending,and metallography,it is found that the defects of the welded joints are greatly reduced,and the tensile properties of the welded joints are increased by 57.6％,showing good performance and meeting production standards.According to the experimental results,it is found that the strength of the welded joint decreases because the welded joint is affected by the thermal cycle during the welding process,and the deformation strengthening of the heat-affected zone is weakened.The welding heat in-put in the center of the weld leads to the burning of the Mg element in the molten pool,the reduction of the β-strengthening phase of the weld structure,and the softening of the weld joint.
thick plate aluminum alloyMIG weldingwelding defectsprocess improvementsoftening of wel-ded joint
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