Mode of SCC in austenitic grades due to chlorides especially, and by hot concentrated caustic?

• A. Transgranular
• B. Transcrystalline
• C. Intergranular
• D. Mixed

Answer: (B)

The key idea here is how the crack path forms during stress corrosion cracking in austenitic stainless steels. In these alloys, especially in chloride-bearing environments and under hot, concentrated caustic, the cracking tends to propagate through the grains themselves rather than along grain boundaries. This transgranular (often described as transcrystalline) path arises because the embrittlement and localized anodic dissolution occur inside the grains under the aggressive conditions, promoting cracks that cut through crystal lattices rather than following weakened grain boundaries. Grain boundaries would only be preferential pathways if the steel were sensitized (grain boundary chromium carbide precipitation), which is not the typical condition described here. Therefore, the mode of SCC is transcrystalline, i.e., through the grains.