难熔金属钼及钼合金焊接研究进展OA

Molybdenum and its alloys,as high-temperature refractory metals,hold the promising engineering application potential in extreme environments.However,these welded joints are easy to have defects,high brittleness,and poor weldability,which severely impede their engineering applications.Through reviewing research progress of welding technologies for molybdenum and molybdenum alloys.The applications of mainstream welding processes including fusion welding,high-energy beam welding(laser welding,electron beam welding),diffusion welding and vacuum brazing in joining of molybdenum and molybdenum alloys were systematically summarized,the existing critical challenges were analyzed,and the future research directions were clarifies,with the aim of providing theoretical and practical support for their efficient and stable joining.Results indicate that the traditional fusion welding is prone to the defects like the cracks and porosity;high-energy beam welding has problems of oxidation and hot cracking;diffusion welding enables the high quality precision joining,yet the issue of the joint embrittlement remains unresolved;brazing is suitable for complex components,with brazing filler development and process optimization being the key to performance enhancement.Current research primarily focuses on the shear strength of joints,while studies on the sealing performance and toughness are relatively scarce.In the future,efforts should be directed toward welding in the low-oxygen environments,the development of novel welding materials and interlayers,and the regulation of the joint microstructure via numerical simulation technology to inhibit the brittle fracture,improve the comprehensive performance of joints,and facilitate the stable application of molybdenum and molybdenum alloys in the extreme high-temperature environments.