Investigation into high-peak-power nanosecond laser ablation for derusting EH36 high-strength steel

In this paper, a high-peak-power nanosecond laser derusting experiment is developed to meet the high-efficiency and high-quality laser derusting requirements of EH36 high strength steel in shipbuilding, marine engineering and other fields. By integrating master oscillator power amplifier technology, a beam shaping system, and a three-dimensional spatial light transmission system, the device achieved a line laser output with a pulse width of 66.7 ns, repetition frequency of 5.6 kHz, maximum peak power density of 67 MW/cm², and single-pulse energy of 536 mJ. Laser derusting experiments were conducted through controlled variations in peak power density, scanning passes, and scanning rate. Comparative analyses of surface roughness, elemental composition, and microscopic morphology of EH36 steel revealed optimal cleaning parameters: peak power density of 67 MW/cm², 2 scanning passes, and scanning rate of 400 mm/s. This configuration achieved optimal cleaning efficiency of 28.8 m²/h, surface roughness Sa of 3.34 μm, and rust removal rate of 95%. The results demonstrate effective removal of oxide layers while maintaining substrate integrity, providing technical reference for industrial-scale laser cleaning applications in heavy steel structures.