Stress corrosion cracking
Stress corrosion cracking is a crack-forming corrosion that occurs under the influence of static tensile stresses and specific corrosive media. It leads to cracks in the weld and can destroy the material.
Physical-Chemical Mechanism
Stress corrosion cracking occurs when static tensile stresses exist in a metal part and it's exposed to a corrosive medium like water or hydrochloric acid. These stresses can come from mechanical loading, welding, or manufacturing processes. The stresses put material at the crack tips under tension, concentrating corrosive agents like oxygen and water there. This accelerates the corrosion reaction and causes further cracking.
Metallurgical Relevance & Welding Risks
Stress corrosion cracking is especially dangerous for welds, since it often occurs there. It can destroy the weld and damage the whole part. That can lead to safety issues and higher maintenance and repair costs.
Shop Practice & Action Items
To avoid stress corrosion cracking, take these steps:
1. Stress relief: After welding, use a mechanical or chemical method to remove static tensile stresses.
2. Corrosion protection: Apply protective surface treatments, like painting or galvanizing.
3. Material selection: Use materials with low stress susceptibility or improve crack resistance through careful process planning.