Transgranular stress corrosion cracking has been observed in which stainless steel grade under certain conditions?

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

Answer: (A)

Transgranular cracking means the crack advances through the grains themselves, rather than along the grain boundaries. This path is favored in materials that fracture in a more cleavage-like, brittle manner under tensile load in corrosive environments.

Martensitic stainless steels are high-strength and relatively brittle compared with other stainless grades. When they are under tensile stress and exposed to aggressive media (such as chlorides) under certain temperatures or stress levels, they tend to crack through the grain interiors rather than along grain boundaries. That behavior aligns with transgranular stress corrosion cracking, which is why this grade is the best match for observing TG SCC under those conditions.

Ferritic and austenitic grades can also experience SCC, but their typical cracking modes differ and are more commonly intergranular under sensitizing conditions, or they show different SCC tendencies in various environments. Precipitation-hardening grades have their own susceptibility patterns, but the transgranular mode in martensitic stainless steels is the classic pairing with this description.