Evaluation of the resistance to erosion of laser treated stainless steel used in direct contact with food products

The non-magnetic austenitic grade stainless steel 1.4401 (316) is one of the most popular alloy used in the food processing industry. Just as any other material intended to be used in contact with food products, the mentioned steel shall meet rigorous hygienic requirements. Its surfaces shall repel contaminants and must not be prone to retaining them. It shall also be easily cleaned and sanitized. A common method for solving this comes down to turning the surface of the steel hydrophobic and/or oleophobic. This can be done either by applying a coating, which lowers the surface energy, or by modifying the morphology of the surface itself. The second can be done by performing laser ablation using pulsed laser. This article presents the results of an experimental evaluation of the resistance to erosion of textured hydrophobic surface. A test sample was first treated with near-infrared fibre laser and was then subjected to extreme hydrodynamic erosive conditions by exposing it to intense cavitation. After the laser treatment, the wetting angle increased by nearly 47%, but then dropped by almost 80% after 20 h of cavitation. After 40 h of cavitation, the surface became super hydrophilic.