Unveiling the effects of laser scanning direction and processing parameters on heat transfer and ablation behavior of CFRP

Carbon fiber reinforced plastic (CFRP) has found extensive applications in aerospace, automotive, and biomedical fields owing to its exceptional mechanical properties. Nanosecond pulsed laser processing offers a promising avenue for treating CFRP laminates; however, the inevitable thermal damage during processing may significantly degrade the surface integrity. An in-depth analysis of the correlation between ablation characteristics of CFRP and laser processing conditions is essential for understanding the complex heat transfer and ablation mechanisms during laser processing of CFRP and is a prerequisite for improved control of thermal damage. This study examines the thermal transfer and ablation behavior of CFRP subjected to nanosecond laser ablation, focusing on how laser scanning direction and processing parameters influence the surface characteristics of the laser-ablated regions. The results indicate that the width of the heat-affected zone (HAZ) increases with increasing laser power, decreasing scanning speed, and decreasing scanning pitch. Moreover, the scanning direction plays a crucial role in determining the HAZ characteristics and material removal rate. Processing CFRP along the 0° direction relative to the carbon fiber orientation yields higher efficiency and less thermal damage compared to the 90° direction. Chemical composition analysis reveals that laser ablation induces a structural transformation in carbon fibers, shifting from sp2 graphite-like lattice orbitals to sp3 hybird orbitals. Numerical simulations further elucidate the heat transfer and ablation mechanisms under various experimental conditions. This study contributes to a deeper understanding of the laser-CFRP interaction, facilitating the development of high-integrity CFRP surfaces and broadening their practical applications across multiple industries. © Elsevier Ltd