Magnesium-lithium alloy (Mg-Li alloy) is a type of rising ultra-light material with a series of advantages, such as high specific strength and specific stiffness, high Young's modulus, excellent plasticity and impact toughness, which is one of the ideal structural materials in aerospace and aviation, weapon, nuclear, vehicle, medical equipment and other fields. With the rapid development and application of Mg-Li alloy, new requirements for the joining of Mg-Li alloy arise. Appropriate welding methods need to be developed to achieve the join and replace the mechanical joint such as riveting gradually. Currently, the welding methods of Mg-Li alloy mainly focus on tungsten inert gas arc welding (TIG wel-ding), laser welding, electron beam welding and friction stir welding. The core problem of fusion welding is the control of heat input. Improper control will lead to welding defects, such as grain coarsening, element loss and incomplete penetration, etc. Although friction stir welding can avoid these defects to a large extent, deteriation in joint elongation is difficult to avoid. At present, the research mainly focus on weld process, microstructure and mechanical properties of joints, and the welding of Mg-Li alloy is successfully realized through the exploratory research. Currently, many remarkable achievements about study of Mg-Li alloy welding process have been achieved, and well-formed and defect-free joints can be obtained under a wide process window. Under the appropriate welding process, the grain in the weld zone was significantly refined, and nanoscale grains even appeared. In some studies, the microstructure distribution of the welded joint was uniform, and extremely narrow heat affected zone was successfully obtained. Most studies have shown that the tensile strength of joints and the hardness of welds are improved, and artificial aging treatment to restore the elongation of joints has a good prospect. In order to further popularize the practical application of Mg-Li alloy welding technology, the joint formation, microstructure and mechanical pro-perties obtained by the above welding methods were reviewed in this paper. The core problems and probable solutions of different welding me-thods in Mg-Li alloy welding were analyzed and discussed. The exploration direction of Mg-Li alloy welding technology in the future was considered and prospected. © 2022, Materials Review Magazine. All right reserved.
