Effect of strain rate on stress corrosion cracking in duplex type 304 stainless steel weld metal

The influence of strain-rate on the stress-corrosion cracking properties of wholly austenitic Type 304 base metal and duplex austeno-ferritic Type 304 weld metal in boiling MgCl₂ was investigated using constant extension rate tensile testing techniques. Transgranular SCC in both base and weld metals is preferred at low strain-rates, while intergranular cracking in the base metal and interphase cracking along the austenite-ferrite interface in the weld metal are preferred at higher strain-rates. Promotion of the intergranular stress-corrosion cracking in the base metal and “interphase-interface” stresscorrosion cracking in the weld metal with increases in strain-rate may be mechanistically analogous. Stress-induced alterations in the grain or interphase boundary defect structure may make these regions preferentially susceptible to dissolution. W. A. BAESLACK III, Lt., USAF, formerly with Rensselaer Polytechnic Institute, Troy, New York