Corrosion of Austenitic Stainless Steel

Abstract

This thesis work focuses on the corrosion behaviour of austenitic stainless steel welds in chloride containing environments. The initial aim was to develop a new method for corrosion testing of welded austenitic stainless steel. The motivation for such work was that previous results indicated that the current accelerated corrosion tests are too harsh for these welds. The specific application is for a stainless steel automotive fuel tank that is being investigated as a possible alternative to the standard plastic fuel tank. For this study, lab-welded samples of 304L and 301 stainless steel were provided by Outokumpu for accelerated corrosion testing. The corrosion mechanisms of most concern were stress corrosion cracking and intergranular corrosion. Three different accelerated corrosion test (ACT) cycles were used. These included two standard Volvo Cars cycles and one new experimental cycle. Chloride environments containing NaCl and a mixture of NaCl and CaCl2 were included. Lastly, an ASTM standard for stress corrosion cracking of stainless steel was utilized. Results showed that the lab-welded samples were corrosion resistant under all conditions due to excellent weld quality. The two different chloride environments did not show significant differences in corrosive attack.