Improvement of the surface performance of stainless steel regarding health and food industry applications
In the area of food industry equipment, biological and chemical neutrality of stainless steel surfaces are becoming decisive factors in choosing a material. The development of stainless steel over more than 60 years is explained by the fact that it corresponds exactly to the requirements expected for materials placed in contact with food, for example chemical and bacteriological neutrality with regard to foodstuffs, corrosion resistance and material ageing. Industrial cold-rolled stainless steels were investigated in terms of surface chemistry, cleanability, metal release and corrosion resistance. As far as the surface properties were concerned, the passive film was modified by thermal and electrochemical treatments. The most drastic treatment was the thermal one as on heated surfaces, the outer passive film was strongly enriched in iron. However, this modification was not stable on aged materials and an important metal release was observed. The electrochemical treatment was the most promising one as iron enrichment was observed in the grown passive film and the localised corrosion behaviour was not affected. The releasing tests also indicated stability on aged materials in contact with dairy solutions. Moreover, this treatment modified the material surface properties and consequently limited surface biocontamination. Finally, a secondary process had a strong effect on the surface properties. Welding induced a differential migration of metallic element leading to the decrease of the corrosion resistance. Forming increased the surface roughness and led to a decrease in cleanability performance. Finally, the secondary process masked the initial surface properties induced by thermal or electrochemical treatments performed on flat surfaces.
Bibliographic Reference: EUR 22381 EN (2006), 99 pp. Euro: 15
Availability: Katalogue Number: KI-NA-22381-EN-S The paper version can be ordered online and the PDF version downloaded at: http://bookshop.europa.eu
ISBN: ISBN: 92-79-02651-8
Record Number: 200719299 / Last updated on: 2007-07-10
Original language: en
Available languages: en