Corrosion Behavior of Martensite-based Stainless Steels in the NaCl Solutions Saturated with CO2 Containing Multiple Impurity Species

Abstract The corrosion behavior of martensite-based stainless steels with chromium (Cr) contents ranging from 13 mass% to 17 mass%, which are commonly used as tubing materials in the oil industry, was evaluated under conditions simulating CO2 injection in Carbon Capture and Storage (CCS). The steels were tested to determine their general corrosion rates and susceptibility to crevice corrosion and cracking. The general corrosion rates of modified (Mod.) 13Cr, 15Cr and 17Cr were smaller than 0.127 mm/y. Therefore, these steels were judged to be applicable for CO2 injection tubing. Crevice corrosion occurred on most of the specimens. Steels bearing higher amounts of Cr, such as 17Cr and S25Cr, displayed shallow-shaped crevice corrosion with depths of less than 25 μm. A review of some standards and their reference literature revealed that shallow-shaped crevice corrosion with a depth of less than the critical depth can repassivate. When crevice corrosion having a depth of less than 25 μm is judged as acceptable, 17Cr steel is applicable under all the conditions tested in this work. The 4PB specimens of 17Cr steel were free of cracking. These results indicate that 17Cr has sufficient resistance against general corrosion, crevice corrosion and cracking. Based on the material selection procedure in ISO 15156 and the test results at 24 °C, a concept for drawing domain maps for material selection for CCS tubing applications was explained, and then domain maps of 17Cr under several conditions were presented.