Effect of pH and chloride concentration on the corrosion of duplex stainless steel

Abstract

Stainless steels are widely used as structural materials even in aggressive environments due to their good mechanical and corrosion properties. In particular, duplex (austenitic-ferritic) stainless steels are becoming common materials for oil and gas applications, specifically facilities that were built after the 1970s. This expansion in the utilization of such materials can be attributed to their excellent combination of properties, such as higher strength, good resistance to stress corrosion cracking, and comparable cost to conventional austenitic stainless steels. This research is mainly concerned about the corrosion performance of a duplex stainless steel alloy under several conditions using various pH and chloride concentrations at different temperatures. Corrosion rates and pitting morphology of the selected duplex stainless steel were systematically evaluated during this study. The effects of pH and chloride concentrations on the corrosion behavior of duplex stainless steel were carried out in accordance with UNS S32205. The effect of pH was has been determined by using different test solutions at different test temperatures. The duration of immersion tests were set in accordance to the ASTM G48 standard. However, the effect of chloride concentrations on the corrosion of the selected alloy is determined by pitting corrosion measurements using simple metallography and software analysis as well as PREN (Pitting Resistance Equivalent Number).