Stress Corrosion Cracking of Duplex Stainless Steel under Simulated Evaporation Conditions

The susceptibility of 22 Cr and 25 Cr duplex stainless steels to stress corrosion cracking under evaporative seawater conditions has been evaluated using a modified drop evaporation test. Failure of both steels occurred at temperatures as low as 105 °C. Observation of patchy corrosion and occasional pitting beneath the salt layer suggests that the underdeposit chemistry was aggressive for this system and a combination of this chemistry and micro-plastic deformation is considered to be responsible for cracking of the steels. The engineering implication is that existing recommendations for the critical temperature for coating of duplex stainless steel to avoid failures in service may need to be revised.