Temperature dependence of SCC behavior and mechanism of stainless steel 304 in chloride-containing solution

Effects of temperature on stress corrosion cracking (SCC) of stainless steel 304 were studied through electrochemical measurement, X-ray photoelectron spectroscopy and slow strain rate tensile tests combined with electron backscattered diffraction and electron channeling contrast imaging. Results indicate that the electrochemical behavior of the microstructure plays a significant role in SCC mechanism. With the rising test temperature, passive film breaks down; SCC susceptibility increases linearly with the logarithm of passive current density as a result of dislocation slip dissolution, which facilitates transgranular SCC. The formation of strain-induced α '-martensite along grain boundaries weakens passive film and causes intergranular SCC as martensite enhances hydrogen permeation and hydrogen embrittlement (HE). Therefore, HE plays a role in SCC; but the effect diminishes with rising solution temperature, as martensite formation is hindered.