Stress-Modified Welding of Neutron Irradiated Steels

摘要

Catastrophic centerline fractures in the fusion zone have been observed in neutron irradiated steels after welding using the conventional gas tungsten arc (GTA) welding process. Specimens of type 316 stainless steel; Prime Candidate Alloy (PCA) and Sandvik HT-9 were obtained from a capsule irradiated at 200deg C in the Oak Ridge Research Reactor. Severe fusion zone cracking was observed in type 316 stainless steel (up to 75 appm He) and PCA alloy (up to 86 appm He) after GTA welding. No cracking was observed in HT-9 steel with up to 2.5 appm He concentrations. The application of a compressive stress during GTA welding eliminated fusion zone cracking in both 316SS and PCA. The results indicate that the stress-modified welding technique may be used to suppress and cotrol helium-induced cracking during repair welding of irradiated materials.