Jännityskorroosiosäröily

Jännityskorroosiosäröily, often abbreviated as SCC (Stress Corrosion Cracking) in English, is a form of degradation that affects materials when they are simultaneously exposed to tensile stress and a specific corrosive environment. This phenomenon leads to the formation and propagation of cracks, which can ultimately cause catastrophic failure of a component or structure, even under stresses well below the material's normal yield strength.

The process involves a synergistic interaction between mechanical stress and a chemical attack. The corrosive environment attacks the material, often at specific points or areas of weakness. Applied or residual tensile stresses then concentrate at these sites, promoting crack initiation. Once a crack starts, it grows under the combined influence of the stress and the corrosive environment. The crack growth can be intergranular (along grain boundaries) or transgranular (across grain boundaries), depending on the material and the specific corrosive medium.

Common materials susceptible to jännityskorroosiosäröily include certain stainless steels, aluminum alloys, titanium alloys, and polymers. The specific corrosive environments that trigger SCC vary widely and can include chloride solutions, caustic solutions, ammonia, and even moist air containing certain contaminants. Understanding the interplay between stress, material properties, and the environment is crucial for preventing SCC. This often involves controlling stress levels (e.g., through design, residual stress reduction), selecting appropriate materials for the operating environment, and managing the corrosive environment itself.