Factorial Experiments on Laser Pre‐Treatment of Low‐Carbon Steel Welds Prior to the Application of Organic Coatings

ABSTRACT Effects of weld treatment methods on the performance of organic coatings during accelerated offshore cycle tests were statistically investigated. A full factorial design was applied to low‐carbon steel welds with imperfections and varying preparation methods (blast‐cleaning, mechanical grinding, laser‐based treatments). Laser treatment was evaluated as a supplementary method and as a stand‐alone approach. Surface preparation was the dominant investigated main factor influencing coating damage, with additional significant contributions from weld position, imperfection type, and exposure time. Preparation methods combining laser treatment with mechanical treatment performed equivalent to blast‐cleaning. Purely laser‐based methods, however, resulted in significantly higher damage levels. A key limitation of the 100 W ns‐pulsed laser process was the incomplete removal of silicate welding slag, leading to partial remelting and redeposition of glassy residues within weld grooves. The damage accumulation followed a two‐parameter Weibull model. Laser‐assisted weld preparation had the potential as an alternative to blast‐cleaning, provided that weld geometry is properly conditioned and laser parameters are appropriately scaled.