Stress Corrosion Cracking Behavior of 304L Stainless Steel in NaOH Solution at High Temperatures

The stress cracking corrosion behavior of 304L stainless steel in 180-220 ℃, 1.5%-6% (mass fraction) NaOH solution was studied by slow strain rate test (SSRT). The fracture morphology was characterized by scanning electron microscopy and optical microscopy, and the depth and propagation rate of secondary cracks were calculated. The results showed that the secondary crack growth rate could respectively good reflect the stress corrosion cracking sensitivity of metals in “alkali brittle system”, and the stress corrosion cracking sensitivity index of 304L in above high temperature NaOH solutions had little difference. The micro morphology of the fracture surface after SSRT showed that the sample was ductile fracture, but the macro morphology found secondary cracks. The depth and growth rate of secondary cracks increased with the increase of temperature and NaOH content. 304L might have a certain stress corrosion cracking tendency in 180 ℃, 1.5% NaOH solution.