metals Review Research Status and Progress of Welding Technologies for Molybdenum and Molybdenum Alloys Qi Zhu 1, Miaoxia Xie 2,*, Xiangtao Shang 2, Geng An 1,3, Jun Sun 3, Na Wang 1, Sha Xi 1, Chunyang Bu 1 and Juping Zhang 1 1 Technical Center, Jinduicheng Molybdenum Co., Ltd., Xi’an 710077, China;
[email protected] (Q.Z.);
[email protected] (G.A.);
[email protected] (N.W.);
[email protected] (S.X.);
[email protected] (C.B.);
[email protected] (J.Z.) 2 School of Mechanical and Electrical Engineering, Xi’an University of Architecture and Technology, Xi’an 710055, China;
[email protected] 3 State key laboratory for mechanical behavior of materials, Xi’an Jiaotong University, Xi’an 710049, China;
[email protected] * Correspondence:
[email protected]; Tel.: +86-181-4902-5125 Received: 28 December 2019; Accepted: 14 February 2020; Published: 20 February 2020 Abstract: Owing to its potential application prospect in novel accident tolerant fuel, molybdenum alloys and their welding technologies have gained great importance in recent years. The challenges of welding molybdenum alloys come from two aspects: one is related to its powder metallurgy manufacturing process, and the other is its inherent characteristics of refractory metal. The welding of powder metallurgy materials has been associated with issues such as porosity, contamination, and inclusions, at levels which tend to degrade the service performances of a welded joint. Refractory metals usually present poor weldability due to embrittlement of the fusion zone as a result of impurities segregation and the grain coarsening in the heat-affected zone.