Investigations on chip formation mechanism and surface integrity analysis in LAM of 45%SiCp/Al composites

Laser-assisted machining (LAM) is a new manufacturing technology to improve the productivity of metal matrix composites (MMCs). However, there are many arguments about whether LAM is good for improving chip deformation, and there is also a lot of debate about surface integrity. The quality of surface integrity is closely correlated with the chip formation in LAM of MMCs depending on the processing conditions and constituents in composites. In this study, interaction process between 1064-nm diode laser and 45%SiCp/Al composites is theoretically described. The chip formation mechanism in LAM of 45%SiC/Al composites at different temperatures is revealed by analyzing the chip root morphology and chip chip-breaking process with an assistance of finite element model. The thermal mismatch stress of particles and matrix in the shear deformation zone are derived applying the Eshelby equivalent strain equations and thermal expansion coefficient and elastic modulus. Based on these, mechanisms of chip deformation and fracture in LAM are elucidated further. The various surface morphology (plastic side stream, surface scratches, particle pull-out, particles broken) dependent on the coupling of the force loads, thermal loads, and removal model of reinforcement particles are deeply investigated through LAM experiments. The surface morphology experiment results show that particle aggregation occurs between two or more adjacent SiC particles because the multiple SiC particles appear simultaneously at cutting path of tools. An analysis model was established to evaluate particle agglomeration in LAM according to the influence rules of tool geometry and particle size. Moreover, technological experiments focus on the effect of LAM variables, like laser power and scanning velocity on the microhardness and surface roughness of cross-section layer, mechanisms of which are analyzed from multiple perspectives.