镁锂合金搅拌摩擦焊接工艺特性分析

Investigation on friction stir welding of Mg-Li Alloy

针对退火态的MBLS10-200镁锂合金,分析了搅拌工具、焊接工艺参数对焊缝成形、接头组织特征及力学性能的影响,并对接头的塑性损失机理及提升技术进行分析.结果表明,在焊缝成形良好的工艺参数范围内(转速800~1 600 r/min、焊接速度200~500 mm/min),接头大多断在母材,强度与母材相当,而断后伸长率则有显著的降低,仅为母材的8%~57%.焊核及热力影响区与母材性能的差异使接头在受拉时产生各区域变形不协调是导致断后伸长率下降的根本原因.采用退火处理可以在接头强度不下降的同时,有效提升接头断后伸长率,可达到母材的96%.

The friction stir welding of MBL10-200 Mg-Li alloy with a thickness of 3 mm was investigated.Concentrating on the process characteristics,the effects of friction tools,welding parameters on weld appearance,and mechanical properties of the joints were studied.The mechanism and solution of joint ductility loss were both investigated.The results show that with relatively wide process window(rotation speed 800~1 600 r/min,welding speed200~500 mm/min),welds with good appearance can be obtained.Joints under most welding parameters fracture at base metal,and shows comparable strength with base metal.The joint elongation shows apparent decrease,8%~57%of base metal under varied welding parameters.The non-uniform deformation of WNZ,TMAZ and base metal in the joint is the main reason of ductility loss.Annealing of the welded joints can effectively increase the elongation,nearly 96% of base metal.