Which protective measure is commonly effective against stress corrosion cracking?

• A. Thermal quenching
• B. Cathodic protection
• C. Mechanical shielding only
• D. Increased tensile stress

Answer: (B)

Stress corrosion cracking happens when a material under tensile stress is in a corrosive environment, so protection focuses on removing or reducing the driving forces for crack growth. Cathodic protection works by making the metal surface more cathodic (pulling its potential to a negative value) through sacrificial anodes or an impressed current. This lowers the anodic dissolution at crack tips and along susceptible regions, slowing or stopping crack initiation and propagation. It’s a common, practical method for steel structures in contact with seawater or soil, pipelines, and submerged components. Of course, protection levels must be carefully controlled to avoid drawbacks like hydrogen embrittlement in some alloys, but overall cathodic protection decisively reduces the electrochemical driving force behind SCC. The other measures don’t address this core cause: inappropriate stresses or environmental exposure, or methods that don’t meaningfully alter the electrochemical conditions.