Effect of flow rate on corrosion behavior of 316L stainless steel welding seam in liquid lead bismuth eutectic

Liquid lead bismuth eutectic (LBE) is often used as the coolant of Accelerator Driven Sub-critical System(ADS) in nuclear industry, and 316L stainless steel is often used as a nuclear stainless steel for its excellent performance. However, the high-speed liquid LBE will lead to the corrosion of 316L stainless steel welding seam and the corroded products will also pollute the liquid LBE, so the study of the corrosion resistance of 316L stainless steel welding seam in flowing liquid LBE is of great significance. This paper investigated the corrosion behavior of the Tungsten Inert Gas (TIG) welding seam of 316L stainless steel in inflowing liquid LBE at 550 °C for 1 500 hours (The relative flow rates were 1.70, 2.31 and 2.98 m/s). The results indicated that a double oxidation layer was generated on the surface of three groups of samples, and the outer oxide layer and the inner oxide layer were composed of the Fe₃O₄ and FeCr₂O₄, respectively. The compactness of the inner oxide layer is better than the outer oxide layer; With the increase of the relative flow rate, the mass transfer process of the elements became faster, the oxidation corrosion became more serious; and the inner oxide layer became thicker.