Today, laser cleaning is attracting attention as one of the methods to remove paint coating before repaint as it does not require chemicals or water and also is superior in terms of noise and safety during the treatment. Various studies have been conducted on the surface preparation of civil engineering steel structures by using laser cleaning. However, the effect of heat and oxide film from laser cleaning which may affect the mechanical properties of the steel and the coating durability after repainting has not been clarified yet.
Therefore, in this study, CW laser cleaning with various irradiation conditions on SM400B steel plates with anti-corrosion coatings.
The experiment parameter refers to the number of times of laser irradiation. There are three conditions: the first involves removing the upper layers of the paint coating and then recoat the removed layers over it, the second condition involves completely removing the paint coating and then recoating all of the layers, and the third condition involves excessive irradiation after completely removing the paint coating to investigate the effect of excessive irradiation and then recoating all of the layers.
Changes and differences in the steel surface of each specimen are evaluated by appearance, surface roughness, and chemical composition of the treated surface to examine the degree of oxidation. In addition, to investigate changes in the mechanical properties, thickness change measurement, cross-sectional observation, Vicker’s hardness test through the thickness, and tensile test will be conducted. Combined cyclic corrosion test will be conducted on specimens that have been recoated after laser cleaning and the adhesion strength test will be performed to investigate the corrosion durability of the recoating.
Comparing these results with specimens treated by sandblasting which is currently standard on the surface preparation of civil engineering steel structures, suitable laser irradiation conditions for surface preparation to remove paint coating will be examined.