Evaluation of the hygienic performance of laser treated austenitic stainless steel intended for direct contact with food products

The austenitic stainless steel 1.4401 (316) is one of the most widely used non-magnetic corrosion resistant alloy in the food processing industry. Its primary components are chromium, nickel and molybdenum. In order to be used in direct or indirect contact with food products, all the materials have to meet some rigorous requirements. Their surfaces shall not be prone to retaining contaminants, and shall not undergo corrosion and/or erosion. One approach for achieving this is to make the surface of a material hydrophobic and/or oleophobic. This can be done by applying coating on the surface or by altering its morphology. This article presents an experimental evaluation of the usage of infrared fibre laser beam for treatment of the surface of the stainless steel mentioned above, and the effects in terms of increased wetting angle (contact angle). Scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) was used for the evaluation. Wetting angle of nearly 86º was measured on the surface of electro- chemically polished sample of the mentioned stainless steel. After laser ablation, the angle rose to nearly 130º, which is an increase of almost 50%.