Influence of Compound Laser on Paint Removal Depth and Performance of 6005A Aluminum Alloy

6005A aluminum alloy is widely used in the railway industry due to its excellent performance. Paint removal from the railway surface is an important step in the repair process. Compared with continuous laser that damages the substrate and low efficiency of pulsed laser, compound laser can achieve efficient paint removal. In this study, paint removal from the surface of 6005A aluminum alloy was performed using a combination of continuous and pulsed fiber lasers. When delay time was 0.4 s, the maximum paint thickness reduction of one single machining was 93 μm, which was 22.4% better than single laser efficiency. Performance tests on the surface of 6005A aluminum alloy substrate showed that, when delay time was 0.4 s, the minimum surface roughness was 1.04 μm and the ablation of paint from the substrate surface was observed by electron microscopy. There were no obvious changes in grain size after compound laser paint removal. The contact angle of the substrate surface after compound laser paint removal was 87.3° on average, which was 13.4% less than the original surface. It was more hydrophilic to make it easier to repaint. This research provided the theoretical foundation for the application of compound laser in railway paint removal.