Jännitysrasituskorroosio

Jännitysrasituskorroosio, often abbreviated as SCC (Stress Corrosion Cracking), is a form of material degradation that occurs when a susceptible material is exposed to a specific corrosive environment while under tensile stress. This phenomenon can lead to unexpected and premature failure of components, even at stress levels well below the material's yield strength.

The process of SCC involves the interaction of three key factors: a susceptible material, a specific corrosive environment, and tensile stress. The material's susceptibility is often related to its chemical composition, microstructure, and past processing. The corrosive environment can range from atmospheric conditions to aggressive chemical solutions, and it is the specific nature of the environment that dictates which materials are susceptible. The tensile stress can be applied externally or can be residual stress from manufacturing processes like welding or cold working.

SCC typically initiates at a surface defect or initiation site and propagates into the material, forming cracks. These cracks can grow relatively slowly or rapidly, depending on the specific conditions. The fracture surface of an SCC crack often exhibits a brittle appearance, even in normally ductile materials.

Preventing SCC involves controlling one or more of the contributing factors. This can include selecting more resistant materials, modifying the environment to reduce its corrosivity (e.g., through coatings, inhibitors, or changing operating conditions), or reducing the applied tensile stress (e.g., through design changes or stress relief treatments). Understanding the specific combination of material, environment, and stress is crucial for effective prevention and mitigation strategies.