Which grade is described as susceptible to chloride SCC when heat-treated to very high strength?

• A. Martensitic
• B. Ferritic
• C. Austenitic
• D. Precipitation Hardened

Answer: (D)

Chloride-induced stress corrosion cracking tends to show up in high-strength stainless steels, because the combination of tensile stresses and a brittle, hard microstructure makes crack initiation and propagation easier in a chloride environment. Precipitation-hardening stainless steels achieve very high strength through aging precipitates, which markedly increases hardness and reduces ductility. That aging also creates microstructural features and residual stresses that, when exposed to chloride ions, promote passive-film breakdown and hydrogen-assisted cracking along cracks or grain boundaries. So, in the context of being heat-treated to very high strength, precipitation-hardening stainless steels are the ones described as susceptible to chloride SCC.