Low-Temperature Stress Corrosion Cracking of Austenitic and Duplex Stainless Steels Under Chloride Deposits

Corrosion performance of austenitic-ferritic (duplex) stainless steels UNS S32101, S32202, S32304, and S32205 and austenitic stainless steels UNS S30403 and S31603 was studied in the presence of chloride deposits simulating non-rinsing atmospheric conditions. The effect of temperature, relative humidity, concentration, and composition of the chloride deposits on the tendency for atmospheric, low-temperature, chloride-induced stress corrosion cracking (SCC), pitting, and selective corrosion was assessed using prestressed samples with a circular weld. In the presence of calcium chloride, SCC was observed at temperatures as low as 20°C and 30°C on the austenitic stainless steels UNS S30403 (Type 304L) and UNS S31603 (Type 316L), respectively. The only cases of SCC of tested duplex stainless steel grades were found at 70°C, which otherwise suffered mainly selective dissolution of the ferrite phase with one order lower depth of attack. The initiation of SCC and selective/pitting corrosion was governed by the e...