Laser Cleaning Process for Low-Pressure Turbine Blade Paint Removal with Remelting Suppression

This study aims to develop an efficient laser cleaning process for removing paint coatings from low-pressure turbine blades while suppressing substrate remelting, focusing on elucidating the underlying paint removal mechanisms on coated aluminum alloy substrates. A pulsed fiber laser (1064 nm, 100 ns) was used to perform single-factor and orthogonal experiments, with laser power (70–100 W), scanning speed (1000–3000 mm/s), and repetition frequency (150–300 kHz) as the main variables. The energy density for each of the 16 orthogonal test samples ranged from 11.9 to 51.0 J/cm2. Complete paint removal without substrate damage was achieved within an optimal energy density window of approximately 17–27 J/cm2 (e.g., 23.8 J/cm2), whereas higher values above 35 J/cm2 (e.g., 35.7 J/cm2) frequently caused localized remelting and pitting. The optimized parameter combination (90 W, 1500 mm/s, 300 kHz) achieved 98% paint removal efficiency in four passes with no observable substrate degradation. Mechanistic analysis indicated that low-to-moderate energy densities promoted interfacial debonding and controlled film ablation, while high energy densities led to substrate melting and reflow. This work clarifies the quantitative correlation between laser parameters, paint removal mechanisms, and remelting suppression, providing a scientific basis for turbine blade maintenance applications.