The stress corrosion cracking susceptibility of a 316L stainless steel in concentrated acetic acid solutions at 90 °C has been investigated. The solutions tested were designed to model a chemical process
environment and contained 70 % to 90 % acetic acid with 1500 ppm Br and 200 ppm Na + as the base chemistry. Of key interest was the impact of CI ions, in the concentration range 200-3000 ppm, representing uncontrolled excursions in system chemistry. Proof ring and slow strain rate tests were conducted in the acetic acid solutions with and without chloride and one proof ring test was conducted with cyclical incursions of chloride ions. In the timescale of the proof ring tests, fracture of the specimens did not occur for any of the test conditions but sectioning of the specimen revealed intergranular cracks in the 90 % acetic acid solutions containing 1500 ppm chloride but not 400 ppm. The crack growth rate, estimated from proof ring specimens exposed for varying times, decreased with crack depth and was of the order of ...
Keywords: 316L stainless steel, acetic acid, bromide, chloride, environment assisted cracking.