Effect of halide anions and temperature on initiation of pitting in Cr–Mn–N and Cr–Ni steels

AbstractAbstractThe pitting corrosion of Cr18Mn12N and Cr18Ni9 steels in halide solutions (F−, Cl−, Br− and I−) has been investigated. The study involved cyclic potentiodynamic polarisation tests with subsequent examination of the specimens by both optical and scanning electron microscopy. Values of the critical concentrations of halide ions, [X−]cr, beyond which pitting occurs, as well as breakdown potentials for pitting in chloride solution, have been established. In addition, the effect of the temperature over the range of 5–80°C on the critical chloride ion concentration [Cl−]cr has been investigated and it has been found that temperature has a negligible effect beyond 40°C.Keywords: PITTINGCRITICAL CONCENTRATIONHALIDESTAINLESS STEEL