Effects of Mo, Cu, Si and P on Anodic Behavior of 17 Cr Steels

Abstract

Abstract Effects of additions of 1–3 percent molybdenum alone and in combination with copper, silicon and phosphorus on the anodic behavior of 17 Cr stainless steel were evaluated by potentio-dynamic polarization measurements and film breakdown studies in sulfuric acid. As molybdenum content increased the critical current density for passivity decreased, passivation potential shifted in the active direction and stability of passive film, as revealed by breakdown times, increased. Copper and silicon additions tended to enhance effects of molybdenum, in general, while phosphorus was detrimental. No addition had significant effect on potential at which transpassive behavior occurs. All samples displayed a wide passive region over which anodic protection could be applied in sulfuric acid medium.