Corrosion of AlSi 304L Austenitic Stainless Steel in Non-Stationary Aqueous HCl + NaCl Solution

The paper describes the process of stress corrosion in a Ø50 mm rod made of AISI 304L austenitic chromium-nickel steel. Discs cut off from the steel rod were moved at a speed of 1.25 m/s for a test period of 408 h in a corrosive environment of aqueous solution containing 3% HCl and 8.6 g NaCl at room temperature. It was found that deepest cracks and irregular pitting occurred locally in areas of microstructure containing grains of hard lamellar &alpha' martensite and along boundaries between filamentary delta ferrite (Feδ) precipitates and &alpha′ phase. The corrosion developed in a trans-crystalline manner with branches propagating along boundaries of lamellar &alpha′ phase grains.