Influence of laser cleaning on coating adhesion and microhardness of steel substrate

This study investigates the influence of laser surface cleaning on the properties of a steel
substrate and the adhesion of a protective coating. Two surfaces from which the previous coating
had been removed using different procedures were analyzed: one was prepared by abrasive
blasting, while the other was treated by laser cleaning. The initial surface condition of both test
specimens prior to the application of the protective coating was abrasive blasted to a cleanliness
grade Sa 2.5 in accordance with ISO 8501-1, with a medium surface profile defined according to
ISO 8503 G.
Following laser cleaning and abrasive blasting, a new epoxy primer coating was manually
applied to evaluate the influence of surface preparation on coating adhesion. Surface roughness
was measured using an Elcometer 224 device in accordance with ASTM D4417. Coating
adhesion was determined by using the pull-off method with an Elcometer 510 device in
accordance with ASTM D4541. Cross-sectional metallographic analysis and microhardness
measurements were also performed to identify possible microstructural changes and variations in
hardness distribution induced by laser treatment.
The comparative analysis of abrasive-blasted and laser-cleaned substrates enables assessment of
the thermal effects generated during laser cleaning and their correlation with coating adhesion
performance. The results obtained contribute to evaluating laser cleaning as a reliable surface
preparation method prior to recoating corrosion protection systems