Corrosion fatigue describes fatigue due to which condition?

• A. Wear from friction
• B. Pure static corrosion
• C. Fatigue due to cyclic stresses in corrosive environment
• D. Pitting due to static load

Answer: (C)

Corrosion fatigue is the damage that occurs when a material is subjected to cyclic loading while exposed to a corrosive environment. The repeated stress cycles cause cracks to initiate and grow, and the environment accelerates this process by chemical attack at crack tips and at flaws, so failure happens faster than with fatigue in dry conditions. This distinguishes it from purely mechanical wear from friction, which isn’t about chemical attack, and from static corrosion, which occurs without any repeated loading. It’s also different from pitting caused by a static load, which is localized corrosion without the influence of cyclic stress. In aviation, this synergistic effect explains why components exposed to repeated pressurization cycles in humid or salt-laden air can fatigue sooner than expected.