Influence of heat treatments and disinfection treatments on corrosion resistance and food-grade of martensitic stainless steels

The aim of this work is to evaluate how the application of heat treatments (quenching and tempering) affect the corrosion resistance and food-grade of three different martensitic stainless steels: AISI420B, AISI440C and BÖHLER M340. For each steel three different heat treatments were applied and the samples obtained were characterized by accelerated corrosion tests, leach tests (according to DM 21/03/1973) and HV1 surface microhardness tests. The results obtained confirm that, for all the steels tested, the quenching followed by tempering at low temperature treatment guarantees compliance with the limits set by the DM in terms of leaching, allowing to obtain an excellent compromise between mechanical properties and corrosion resistance. However, M340 steel results as the best in terms of corrosion resistance and food-grade.