The effects of strain rates (5.0×10⁻⁶ s⁻¹∼5.0×10⁻⁴ s⁻¹), applied potentials (−0.6 V∼0 V, SCE) and temperature (room temperature to 60°C) on the stress corrosion cracking of 304L stainless steel has been investigated in 5 mol/l H₂SO₄/0.1 mol/l NaCl solution using a dynamic straining method.
Stress corrosion cracking occurred under the condition where Cl⁻ ions acted as a corrosion inhibitor. The stress corrosion morphology changed, depending upon the strain rate and/or the applied potentials. A change of the crack mode was explained by considering both factors of a slip step formation rate and a corrosion rate of slip steps. Although the crack propagation rate increased with increasing strain rate or anodic potential, it did not exceed the slip step formation rate. The crack propagation rate also increased with increasing temperature, excepting a condition under which a repassivation rate increased with temperature. An apparent activation energy of 28 kJ/mol was obtained for the stress corrosion cracking process.
A possible mechanism of the stress corrosion cracking and a morphology of corrosion attack relative to a transition from stress corrosion to general attack were discussed in detail.