SCC Stress Corrosion Cracking Of Duplex Stainless Steel 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 stainless steel 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 steel
- Duplex stainless steel
- High nickel austenitic stainless steel
The resistance to SCC makes duplex stainless steels suitable materials for many processes which operate at higher temperature, notably:
- Hot water boilers
- Brewing tanks
Stainless steel structures in swimming pools are known to be prone to SCC. The use of standard austenitic stainless steel like 304 and 316 is forbidden in this application. The best stainless steels to use for this purpose are the high nickel austenitic stainless steel such as the 6% Mo grades. However, in some cases, duplex steel such as S32205 (1.4462) and the superduplex stainless steel grades can be considered.
Source: Zhejiang Yaang Pipe Industry Co., Limited (www.yaang.com)