Effect of laser power on microstructure and mechanical properties of oscillating laser-arc hybrid additive manufactured high-strength aluminum alloy

Abstract

Oscillating laser was adopted for wire arc additive manufacturing of high-strength aluminum alloy to solve the problems of low forming accuracy and unsatisfactory performances. The effects of laser power on the forming accuracy, microstructure, and mechanical properties of deposited thin-walls were mainly investigated. The results showed that increasing laser power from 1.5 to 2.5 kW improved the flatness of side-wall, and removed the forming defects such as humps, uneven height and overflow. The porosity was decreased from 2.42 % to 1.79 %, and the forming accuracy was increased by 38 %. Moreover, the average grain size of deposited microstructure was reduced by 14 % from 48.55 to 41.67 μm. Owing to these improvements, both the UTS and elongation of deposited thin-wall were improved by 10.1 % and 20.2 %, respectively. The optimized laser oscillation promoted the fast escape of bubbles in molten pool, and also formed stirring effects to transform columnar grains to refined equiaxed grains, thereby improving the mechanical properties of depositions.