镀锌高强钢电阻点焊焊接接头液态金属脆化裂纹研究进展

镀锌高强钢因具有高强度、耐腐蚀以及延展性优良等特点被应用于汽车构件领域，在实现减重的同时，提高汽车安全性能。电阻点焊作为材料连接的重要技术之一，因具有焊接过程简单、热影响区小、焊接变形与应力小及焊接速度快等优点，被广泛应用于连接镀锌高强汽车用钢。但在焊接过程中锌镀层会在电阻热的作用下熔化并渗入至焊点内部，从而在焊接接头形成液态金属脆化裂纹(Liquid metal embrittlement cracks, LME)，液态金属脆化裂纹会使焊接接头在拉伸过程中发生脆性断裂，严重恶化焊接接头的力学性能。从液态金属脆化裂纹形成机理、表征手段和母材显微组织的影响等方面详细总结了国内外在此方面的研究，并归纳出改善镀锌高强钢焊接接头液态金属脆化裂纹的措施，为后续的研究工作提供一定的参考与借鉴。

Research Progress of Grain Boundary Liquid Metal Embrittlement Cracks in Galvanized Ultra-high Strength Automotive Steel Resistance Spot Welded Joints

Galvanized high-strength steel is used in the field of automotive components due to its high strength, corrosion resistance,and excellent ductility. It can reduce weight and improve vehicle safety performance. As one of the important technologies for material connection, resistance spot welding is widely used in the connection of galvanized high-strength automotive steel due to its advantages such as simple welding process, small heat-affected zone, small welding deformation and stress, and fast welding speed.However, during the welding process, the zinc coating will melt under the action of resistance heat and penetrate into the solder joints,thereby forming liquid metal embrittlement cracks(LME) in the welded joints. Brittle fracture occurs, which seriously deteriorates the mechanical properties of welded joints. The domestic and foreign research in this field is summarized in detail from the aspects of the formation mechanism of liquid metal embrittlement cracks, characterization methods and the influence of the base metal microstructure, and the measures to improve the liquid metal embrittlement cracks in welded joints of galvanized high-strength steel are summarized. Provide some reference and reference for the follow-up research work.