Which factor increases IASCC susceptibility in stainless steels?

• A. Neutron irradiation
• B. Low-temperature inert atmosphere
• C. Mechanical polishing
• D. Electroplating thickness

Answer: (A)

Neutron irradiation drives IASCC susceptibility in stainless steels by changing the metal on both microstructural and chemical levels under reactor conditions. The irradiation creates defects and increases dislocation density, hardening the material and raising internal stresses. It also causes radiation-induced segregation at grain boundaries, often depleting chromium and altering boundary cohesion. In the high-temperature, high-oxidizing water environment of a reactor, these boundary changes make grain boundaries more prone to intergranular cracking when the material is under stress. Hydrogen production and diffusion under irradiation further promote crack initiation and growth along those boundaries, accelerating the failure.

The other options don’t introduce the combination of irradiation-driven microstructural changes and reactor-water chemistry that drives IASCC, so they don’t raise susceptibility in the same way.