Corrosion Fatigue
Corrosion fatigue is the destruction of materials due to repeated mechanical loading and corrosive environmental conditions. It leads to a slowly decreasing fatigue strength, without a clear endurance limit.
Physico-Chemical Mechanism
Corrosion fatigue is caused by the combination of mechanical stresses and chemical corrosion. With each cycle between tensile and compressive stress, a microscopic layer of oxide forms on the material surface. This layer grows with each repetition, leading to microcracks and reducing material strength.
Metallurgical Relevance & Risks in Welding
Corrosion fatigue can occur in weld areas, especially when the material is in corrosive media. It leads to a slowly decreasing fatigue strength and increases susceptibility to cracks and fractures under mechanical load. This can cause safety issues and shortened component life.
Workshop Practice & Action Points
To avoid corrosion fatigue, it is important to:
• Treat the weld to be more resistant to corrosive environments (e.g., by passivating processes).
• Check the material before welding and, if needed, use one with higher corrosion resistance.
• Protect or treat the weld in corrosive media to extend its life.