Microstructure and Corrosion Properties of S400E Sorbite Stainless Steel

S400E stainless steel is a new type of sorbite stainless steel that has been developed in China recently. S400E stainless steel exhibits good mechanical properties, corrosion resistance, and weldability due to the alloying elements. However, the corrosion and microstructure role has not been understood extensively. This paper investigates the electrochemical corrosion properties, microstructure, and phase diagram of the new S400E sorbite stainless steel. The corrosion potential and pitting potential of the S400E are higher than the 12Cr13, indicating better corrosion resistance. The microstructure by SEM and EPMA illustrated that chromium carbides are distributed homogenously in the S400E stainless steel but heterogenous in the 12Cr13 stainless steel. The calculated phase diagram shows that the increase in the P element content in the S400E stainless steel will expand the M 3 P and M (C, N) phase regions; furthermore, the calculated phase diagram shows that the S400E stainless steel temperature from 900–1000°C has ferrite and austenite region, whereas 12Cr13 have austenite phase at that temperature.