Effect of oxygen on the corrosion behavior of SS316L in a buoyancy driven Pb–17Li loop

Highlights: ► We examined the role of oxygen in the mitigating corrosion of SS316L by Pb–17Li. ► We compared the ferrite layer formed in the presence and absence of oxygen. ► Introduction of oxygen developed a thinner ferrite layer on the SS316L surface. ► The reduction in thickness was due to the formation of a Cr enriched passive layer. ► The aforesaid protective layer on the surface of SS316L contained LiCrO2 and Cr2O3. - Abstract: Corrosion behavior of SS316L in lead–lithium eutectic in the presence of oxygen was investigated in a thermal convection loop for 1000 h of exposure. At a thermal gradient of 100 K, a 20 μm deep ferrite layer was formed on the exposed surface. Introduction of oxygen resulted in a substantially high chromium depletion from the steel matrix. EPMA profiles revealed the presence of chromium enriched, lead free layer over the surface facing liquid lead–lithium. XRD data confirmed the presence of LiCrO2 and Cr2O3 in this layer. It is expected that this layer at the interface can act as a passive boundary and thus prevent continued corrosion by liquid metal.