What causes fatigue corrosion?

• A. Fatigue corrosion is caused by the combined effect of corrosion and stress applied in cycles to a component
• B. It is caused by static load in corrosion
• C. It is caused by exposure to water alone
• D. It is caused by temperature fluctuations only

Answer: (C)

Fatigue corrosion happens when a corrosive environment and cyclic mechanical stress act on a component. The environment promotes chemical attack and can create pits that become stress risers, while the repeated loading drives crack initiation and propagation with each cycle. This combination accelerates failure far more than either corrosion or cyclic loading alone. If the load were static, you’d mainly see general corrosion or stress corrosion effects, not the rapid crack growth associated with fatigue. If there were just exposure to water without cycling stress, there wouldn’t be the same repeated crack growth and sudden failure. Temperature changes can influence rates, but the defining feature of fatigue corrosion is the synergy of corrosion with alternating stress.