Study on Microstructure and Properties of Mechanical Vibration-Assisted MIG Welded Joint of Aluminium Alloy Car Body

Abstract

Abstract The aluminium alloy MIG welding of car body has problems such as joint softening and porosity in the weld, which directly affects the welding quality of the body structure. In this study, mechanical vibration was introduced into the aluminium alloy MIG welding process as an external excitation by improving the joint microstructure and performance of aluminum alloy MIG welding. In the research process, optical microscope and scanning electronic microscope were used to observe the microstructure of the joint, observe the size of grains, detect the number of pores, test hardness, take tensile test, and study the influence of frequency of external vibration excitation on weld forming, pore distribution, microstructure and mechanical properties. Studies have shown that mechanical vibration can effectively refine the weld grain, reduce the number of weld pores, increase the penetration depth, improve the strength and hardness of the joint, and improve the welding quality of aluminum alloy. And with the increase of vibration frequency, the grain size and number of pores of the weld gradually decrease, and the penetration depth and tensile strength and hardness of the joint gradually increase.