Estimation of Susceptibility to Stress Corrosion Cracking of Type 321 and 347 Weldment in Polythionic Acid Solution for Long Time Service

Abstract

The susceptibility to polythionic acid stress corrosion cracking of stabilized austenitic stainless steel weldments was investigated as a function of their sensitization measured by EPR method. The results showed that type 321 and 347 stainless steels became susceptible to stress corrosion cracking when the sensitization index in EPR test exceeded the value of 10%.
In order to prevent the stress corrosion cracking of the weldment throughout the long time service of 10⁵ hours or more, some countermeasures such as a stabilizing heat treatment should be provided to the type 321 and 347 weldments when they are used over 480°C and 430°C, respectively.