Austenitic stainless steels are susceptible to chloride
stress corrosion cracking (CSCC). The standard UNS S30400,
S30403, S31600
and S31603
grades are most susceptible. Increasing nickel content
and decreasing carbon content improves resistance to
CSCC. High residual or applied stresses, temperatures
above 65-70°C and chlorides increase the likelihood
of CSCC. Crevices and wet/dry locations such as liquid
vapour interfaces and wet insulation are particularly
likely to initiate CSCC. Initiation may occur in several
weeks, in 1-2 years or after 7-10 years in service.
Methods of minimising chloride stress corrosion
cracking:
Improve design
Examples: Fill or
seal crevices, paint under insulation, keep tensile
stresses below the yield
strength, shot peen, provide
galvanic or cathodic protection.
Select a higher nickel content austenitic stainless
steel
Examples: UNS N08028,
N08800, N08904.
Select a stainless steel containing ferrite such as
duplex stainless steels.
Examples: UNS S31803,
S32550, S32760.
Evaluate stress relief.
Stress relief treatments above 400-450°C may sensitize
stainless steel to intergranular
corrosion, refer to
main menu for more information.
