Studies on laser peening using different sacrificial coatings

Laser shock peening usually requires the presence of a sacrificial coating to protect the substrate from undesirable thermal effects generated by laser irradiation. This paper describes an experimental study to identify an adherent sacrificial coating for laser peening of smooth metallic surfaces where black paint does not adhere well. Normal black polyvinyl chloride electrical insulation tape has been found to be a good choice as a sacrificial coating. Laser peening with black insulation tape generated effective laser peening in three different substrates, namely, Ti6Al4V alloy, SAE 9260 spring steel and DIN X20Cr13 martensitic stainless steel. The depth of peening was comparable or better than that generated with black paint. With respect to widely used black paint, black insulation tape not only provides clean, simple and uniform coating but also literally eliminates the time involved in its application (black paint requires multilayer coating with long intermediate curing periods) and removal.