Nanosecond laser processing and surface quality of SiC particle-reinforced AA2024 composite, homogeneous AA2024 aluminum alloy, and SiC: A comparative experimental study

This study performed comparative experiments on ablation behavior and surface quality obtained by nanosecond laser processing of silicon carbide (SiC) particle-reinforced 2024 aluminum alloy matrix composite (SiCp/AA2024), homogeneous SiC, and 2024 aluminum alloy. A nanosecond laser with a pulse fluence range of 0.68 ∼ 6.83 J/cm2 was used at irradiate samples of these materials, which were then ablated by various numbers of scanning passes (1 to 10) at a fluence of 6.83 J/cm2. The material melting could be achieved only for homogeneous AA2024. The ablation depth for SiC exceeded that of the composite, and the former could be ablated with a pulse fluence exceeding 3.42 J/cm2. The composite ablation threshold was higher than 4.10 J/cm2. Due to the thermal transition between the reinforcement and matrix, the melting threshold of the composite’s AA2024 matrix was lower than that of homogeneous AA2024 alloy. Moreover, the ablation threshold of SiC particles exceeded that of homogeneous SiC. The ablated surface roughness for the homogeneous material showed a sudden increase because of melting or oxidization, while that of the composite exhibited a gradual increase. For homogeneous SiC, oxidization accompanied by ablation and the accumulation of oxidization products on the surface deteriorated the laser pulse processing quality, especially in multipass scanning. In contrast, the dispersed distribution of SiC particles in the composite improved the composite’s machining feasibility.