Korroosiorasitusväsymystä

Korroosiorasitusväsymystä, often referred to as corrosion fatigue, is a phenomenon that occurs when a material is subjected to cyclic stresses in a corrosive environment. The presence of a corrosive medium significantly accelerates the fatigue crack initiation and propagation process compared to fatigue in a non-corrosive environment. This synergistic effect can lead to a substantial reduction in the material's fatigue life, often by an order of magnitude or more.

The mechanism involves the electrochemical nature of corrosion and the mechanical nature of fatigue. Corrosive agents can attack the material surface, creating pits or other surface defects. These defects act as stress concentrators, making it easier for fatigue cracks to initiate. Once a crack forms, the corrosive environment can penetrate the crack tip, further accelerating crack growth through processes like anodic dissolution at the crack tip or hydrogen embrittlement, depending on the specific materials and environment.

Factors influencing corrosion fatigue include the type of corrosive environment (e.g., saltwater, acidic solutions), the material's susceptibility to corrosion and fatigue, the applied stress amplitude, stress ratio, and frequency. Understanding and predicting corrosion fatigue is crucial for the design and maintenance of structures and components operating in aggressive environments, such as bridges, offshore platforms, pipelines, and aircraft. Mitigation strategies involve material selection, protective coatings, cathodic protection, and controlling the operational environment.