Stress Corrosion Cracking
Stress Corrosion Cracking in Stainless Steel (SCC)
SCC is a form of corrosion which occurs with a particular combination of factors:
- Tensile stress
- Corrosive environment
- Sufficiently high temperature. Normally 50 deg C but can occur at lower temperatures around 25 deg C in specific environments, notably swimming pools.
Unfortunately, the standard austenitic steels like 304 (1.4301) and 316 (1.4401) are the most susceptible to SCC. The following materials are much less prone to SCC:
- Ferritic stainless steels
- Duplex stainless steels
- High nickel austenitic stainless steels
The resistance to SCC makes duplex steels suitable materials for many processes which operate at higher temperatures and higher humidity, notably:
- Swimming pool environments
- Hot water boilers
- Brewing tanks
Above is a highly magnified view of a crack showing transgranular pattern and branching, typical of chloride stress corrosion cracking of stainless steel. (500X original magnification).