Influence of ultrasonic shot peening on the microstructure and corrosion behavior of AZ80M magnesium alloy

Abstract

This study investigates the impact of ultrasonic shot peening on the microstructure and corrosion behavior of AZ80M magnesium alloy. The corrosion mechanism of AZ80M magnesium alloy was analyzed by examining the surface morphology, micro-crack distribution, and grain refinement. The findings reveal that ultrasonic shot peening induces a gradient structure with nano-scale grains on the surface of the alloy, replacing the equiaxed grains of varying sizes. The surface roughness of the specimens increases significantly after ultrasonic shot peening, whereas the corrosion resistance greatly improves after ultrasonic shot peening + polishing treatment. The improved corrosion resistance can be attributed to the uniform distribution of the microstructure, refined grains, and the formation of a relatively uniform and dense passivation film during the corrosion process. Furthermore, polishing removes the micro-cracks on the surface, reduces surface roughness, and improves corrosion resistance. The study suggests that ultrasonic shot peening + polishing treatment is an effective way to improve the corrosion resistance of AZ80M magnesium alloy.