Influence of chloride ion concentration and temperature on intergranular stress corrosion cracking of austenitic stainless steel: phase-field simulation study

Chloride ion concentration and electrolyte temperature are two critical environmental factors influencing intergranular stress corrosion cracking (IGSCC) of austenitic stainless steel. To elucidate their effects, a phase-field model was developed by integrating chemical reaction kinetics with multi-ion transport, enabling the simulation of multi-ion interactions in the electrolyte. The results indicate that, chloride ions markedly accelerate IGSCC in the initial stage by facilitating the complexation with metal ions and degrading the passive film. The accelerating effect increases with chloride ion concentration but plateaus due to intrinsic limits of metal ion consumption and passive film damage. In the cracking propagation stage, ion diffusion restrictions within the confined cracks dominate the kinetics. Although elevated temperature enhances ion diffusivity, increases metal ion solubility and intensifies complexations with chloride ions, the most critical factor is that high temperature promotes the overall corrosion susceptibility of the solid phase. This is mainly because the enhancement of corrosion susceptibility by high temperature is continuous. Furthermore, although high temperature narrows the stress concentration zone, crack growth still accelerates at elevated temperatures. This can be mainly attributed to the increase in solid-phase corrosion susceptibility induced by high temperature. These findings provide mechanistic insight into the role of chloride ions and temperature in IGSCC initiation and propagation.