Corrosion-induced release of chromium and iron from ferritic stainless steel grade AISI 430 in simulated food contact

Ferritic stainless steel grade AISI 430 with three different surface finishes, glossy, line and abraded has been evaluated regarding changes in metal release rates and corresponding changes in surface composition when immersed in 3 vol% acetic acid at two different temperatures, 40 °C for ten days and 100 °C during three consecutive immersions of 30 min each. Test parameter intervals were set by one of the very few regulatory texts for metal release in food applications, the Italian law text D.M. 21-03-1973, Art. 37. The metal release process was found to be strongly dependent on surface area to solution volume ratio where a specific surface finish would be within the allowed limit, 0.1 mg Cr L−1 for the lowest ratio, 0.5 cm, but exceeded for the highest ratio, 2 cm−1. The amount of released metal increased with increasing temperature and increasing surface roughness (surface finish).Generated data show the regulatory text insufficient and to provide large degrees of freedom, specifically in terms of defining the surface area to solution volume ratio and the acidic cleaning of test vessels, essential parameters to enable reproducible and relevant migration data.