Study on Corrosion Behavior of Weld Bead by Tungsten Inert Gas Welding China Low Activation Martensitic Steel in Static Oxygen-Saturated Pb-Bi at 500°C

China low activation martensitic (CLAM) steel is one of the reduced activation ferritic/martensitic (RAFM) steels that have been widely considered to be the candidate structural materials for the new generation nuclear facilities. Welding is one of the essential technologies for the practical application of CLAM steel, and the compatibility of weld bead with liquid Pb-Bi has been one of the critical problems to improving the service life of apparatus. Static corrosion tests of tungsten inert gas (TIG) welding bead of CLAM steel were conducted in oxygen-saturated liquid Pb-Bi eutectic at 500°C for 200 h to 500 h to study the effect of corrosion time and post-weld heat treatment on corrosion behavior. The surface oxide of CLAM steel weld was a two-layer structure after 200 h of corrosion, but three-layer oxide layers were formed after 500 h of corrosion. With the increase of corrosion time, the corrosion depth of the sample increased and the corrosion rate reduced. The corrosion resistance of the weld bead was lower than that of the base metal. The oxide layer thickness of samples after tempering at 760°C for 1 h was thinner than that of the untreated samples. The results indicated that the corrosion resistance of the weld bead was effectively improved after the post-weld tempering treatment.