Stress Corrosion Cracking Stress corrosion cracking (SCC)

Stress Corrosion Cracking 

Stress corrosion cracking (SCC) is the cracking induced from the combined influence of tensile stress and a corrosive environment. The impact of SCC on a material usually falls between dry cracking and the fatigue threshold of that material. The required tensile stresses may be in the form of directly applied stresses or in the form of residual stresses

Chloride SCC

One of the most important forms of stress corrosion that concerns the nuclear industry is chloride stress corrosion. Chloride stress corrosion is a type of intergranular corrosion and occurs in austenitic stainless steel under tensile stress in the presence of oxygen, chloride ions, and high temperature. It is thought to start with chromium carbide deposits along grain boundaries that leave the metal open to corrosion. This form of corrosion is controlled by maintaining low chloride ion and oxygen content in the environment and use of low carbon steels

Caustic SCC

Despite the extensive qualification of Inconel for specific applications, a number of corrosion problems have arisen with Inconel tubing. Improved resistance to caustic stress corrosion cracking can be given to Inconel by heat treating it at 620^oC to 705^oC, depending upon prior solution treating temperature. Other problems that have been observed with Inconel include wastage, tube denting, pitting, and intergranular attack