Effects of Sensitization and Hydrogen on Stress Corrosion Cracking of 18-8 Type Stainless Steel

Abstract

Austenitic stainless steels always failure in intergranular corrosion, stress corrosion cracking and their synthesis. Moreover, hydrogen also plays an important role in SCC. Effects of sensitization and hydrogen on stress corrosion cracking of 18-8 type stainless steel (304 and 304L) were investigated in this paper. Three states of specimens, including as-received, sensitization and hydrogen precharged, were prepared for this study. Two kinds of environment, involving air and 0.5mol H2SO4 +0.01mol KSCN solution, were selected to compare the SCC sensitivity of different condition of 304 and 304L by the slow strain rate tensile test (SSRT). Fracture morphology was observed by scanning electron microscope (SEM) to check the SCC fracture characteristic. In SEM, evident secondary cracks were found on the fracture surface of 304. Results showed that: 1) hydrogen precharged 304L has high SCC sensitivity (85.7% ) compared with low SCC sensitivity in solution (14.5%), which reveal that SCC of 304L is hydrogen-induced cracking type; 2) 304 stainless steel has high SCC sensitivity (60.8%); 3) sensitization increases the SCC sensitivity of 304 stainless steel (from 60.8% to 71.4%).