A feasibility study on high-efficient laser cutting of SiC particles reinforced aluminum matrix composite using single-pass strategy

Abstract

Conventional machining of particles reinforced metal matrix composite (PRMMC) is very challenging due to the uniform distribution of abrasive reinforced SiC particles, which easily causes machined surface scratches and severe tool wear. The rapid development of high-power fiber laser has made it possible to cut PRMMCs with high efficiency. In this work, high-power fiber laser was employed to cut 5.0 mm thick SiC particle reinforced aluminum (SiCp/Al) composites. The effects of laser power, cutting speed and assist gas pressure on surface morphology and defect characteristics were investigated. The statistical analysis was conducted to investigate interaction between cutting parameters and kerf geometry. A high-resolution confocal laser scanning microscope was used to further analyze machined surface morphology and microscopic defects. Thermal defects were highly related to cutting parameters, which included cataphracted dross, droplet dross, craters, apophyses, microcracks and combustion. Microcracks were prevalent mainly due to the difference in thermal properties between reinforcement and matrix materials. Three dimensional finite element simulation of two-phase SiCp/Al composites was carried out to predict the temperature and stress distribution, and the striation formation mechanisms were further explained. A new method for predicting thermal stress of SiCp/Al composites was proposed and subsequently compared/validated with experimental results.