Study on the morphology and microstructure of 5A06 alloy by high-pulse-frequency pulsed laser micro polishing

Abstract

The surface quality of aluminum alloy seriously affects its service life and following processing quality. The innovative high-pulse-frequency pulsed laser micro-polished 5A06 alloy provides defect-free high-precision micro-domain modified surfaces. The effects of surface morphology and microstructure under processing speed and spot distance were investigated. As the processing speed and spot distance decreased, the macroscopic uniformity increased. The minimum surface roughness was 0.53 μm. The processing speed causes the difference in line energy to affect the spread of the molten pool. Spot distance distinguishes the size of the remelted area. Both affect the surface roughness. After laser micro polishing, the remelting layer and HAZ were observed in the cross-section. The EBSD results show the remelting layer is a single grain but has more small angle grain boundaries, i.e. higher dislocation density. The second phase of HAZ was significantly refined, and the grain size was reduced by 11.36% compared to base material. Mg evaporation in the remelting layer was researched using saturated vapor pressure.