Stress Corrosion:

Stress cracking it is combine effect of static tensile stress and the corrosion environment on the metal. Stress corrosion is characterize by a highly localized attack occurring when over all corrosion is negligible.

For stress corrosion to occur, the presence of tensile stress specific corrosive environment are necessary

The corrosive agents are highly:

• Caustic alkalis and storing nitrate for mild steel.
• Traces of ammonia for brass.
• Acid chloride selection for stainless steel

This type of corrosion is seen in fabricated articles of certain alloys like high zinc brasses and nickel brasses due to the presence of stresses caused by heavy working like rolling drawing or insufficient annealing pure metal are relatively immure to stress corrosion.

It is generally believed that stress corrosion involves in localized electrochemical corrosion occurring along the narrow path, forming anodic area with respect to larger cathodic areas of the metal surface. Presence of stress produces strain which result in localized zone of higher electrical potential. Theses become so chemically active that they are attacked even by mild corrosive environment resulting the formation of crack.

Under sufficiently high tensile stress and specific environment nearly alloys are susceptible to corrosion.