Effects of Elastic Deformation on the Corrosion of 316l in 3.5% Nacl

Abstract

316L is an austenitic stainless steel widely used in BOPs (Blowout Preventers) due to its exceptional properties of corrosion resistance, toughness and mechanical strength in extreme environments. In this study, we will investigate the impact of elastic deformation on the hardening properties and electrochemical behavior of 316L steel in 3.5% NaCl. The results indicate that 316L stainless steel is sensitive to work hardening. In the unstressed state, it has a crystalline structure with randomly distributed dislocations and a hardness of 234 HV10 at the yield point (Re). When hardness reaches its peak (240 HV10), the material reaches the threshold where dislocations can move irreversibly. Dislocation density is then at its maximum in the elastic regime, and the material enters the plastic range. Electrochemical tests carried out on 316L stainless steel under various mechanical stresses show a contrasting influence of stress on corrosion behavior. While the unstressed sample shows a corrosion current density (Icorr) of 2.69 μA, this value drops to 1.25 μA for a sample stressed to 75% of yield strength (Re), indicating improved corrosion resistance. This improvement can be attributed to densification or partial repair of the passive film under moderate mechanical stress. These results underline the importance of carefully controlling the level of mechanical stress to simultaneously optimize mechanical properties and durability in a corrosive environment.