Effect of the distribution of Cr23C6 on the corrosion behavior of S600E sorbitic stainless steel in 3.5 wt% NaCl solution

The influence of the concentrated precipitation behavior of Cr 23 C 6 on the accelerated and electrochemical corrosion behavioral characteristics of S600E sorbite stainless structural steel in 3.5 wt% NaCl solution was investigated. Additionally, the corrosion mechanism of the experimental steel sample in a chloride ion environment was elucidated. The results revealed that chloride ion pitting corrosion and intergranular corrosion mainly occurred in sample in the chloride ion environment. The diameter of the pit was approximately 20–30 μm, and there was a circular intergranular corrosion area with a diameter of approximately 200–300 μm around the pit. The reduction in the concentrated precipitation of Cr 23 C 6 at the grain boundaries significantly enhanced the breakdown potential, decreased the corrosion current density, strengthened the self-passivation tendency of the experimental steel sample, and improved the stability of the passive film on the surface of the corroded sample. The precipitation of Cr in the form of Cr 23 C 6 at the grain boundaries led to the formation of Cr-depleted zones. The weakened passive film in the Cr-depleted zones dissolved, creating pitting sources. Also, increased chloride concentration near the pitting further damaged the weakened passive film around the corrosion pits , resulting in a circular intergranular corrosion area.