Stress corrosion cracking (SCC) is a complex phenomenon that requires three key factors to occur simultaneously:
- Tensile Stress: The presence of tensile stress, either applied or residual, is essential for SCC. This stress can result from mechanical loads, thermal cycles, or welding processes.
- Corrosive Environment: A specific corrosive environment is necessary to initiate and propagate SCC. Common environments include chlorides for stainless steels, caustic solutions for carbon steels, and ammonia for brass.
- Susceptible Material: The material must be susceptible to SCC in the given environment. Factors such as alloy composition, microstructure, and heat treatment can influence susceptibility.
Preventive Measures:
- Stress Relief: Reduce residual stresses through heat treatment, annealing, or stress-relief processes.
- Environmental Control: Minimize exposure to specific corrosive agents known to cause SCC for the material in use.
- Material Selection: Use materials with higher resistance to SCC in the intended service environment.
By addressing these three factors, the risk of stress corrosion cracking can be significantly reduced.