铝锂合金搅拌摩擦焊搭接接头组织及力学性能  

Microstructure and Mechanical Properties of Friction Stir Welded Al-Li Alloy Lap Joints

作　　者：张丹丹[1] 曲文卿[1] 庄来杰[1] 杨模聪 陈洁 孟强[3] 柴鹏[3] 

机构地区：[1]北京航空航天大学机械工程及自动化学院,北京100191 [2]上海飞机制造厂,上海200436 [3]北京航空制造工程研究所中国搅拌摩擦焊中心,北京100024

出　　处：《航空材料学报》2013年第2期24-28,共5页Journal of Aeronautical Materials

基　　金：北京航空航天大学研究生创新实践基金资助

摘　　要：采用搅拌摩擦焊对2mm厚不同铝锂合金进行搭接,并对接头的组织和力学性能进行分析。同时研究了焊接工艺参数、热处理状态对接头性能的影响。研究表明:搭接接头焊核区呈"洋葱环"结构,由细小的等轴晶组织构成;前进侧搭接界面有"钩状"缺陷,对接头力学性能产生不良影响。搭接接头的塑性较差,伸长率仅有3.18%,不及母材伸长率的25%;当转速为800r/min、焊速为200mm/min时,接头的强塑性最佳,抗拉强度达到467MPa(母材的94%);热处理对搅拌摩擦焊焊接头力学性能影响显著,经过人工时效后,接头强度提高了13%～18%,抗拉强度最高达到526MPa,伸长率都有所下降。断口形貌分析表明:接头拉伸断裂是从前进侧的"钩状"缺陷起裂;接头拉伸断口为准解理和韧窝断裂的复合断口。Two different Al-Li plates with 2mm thickness were successfully joined via friction-stir welding method, and the microstructure and mechanical properties of overlap joints were analyzed. The effect of welding parameters and artificial aging on the overlap joints were investigated. The results showed that the typical ＂ onion ring＂ feature occurring in the weld nugget zone consisted of refined and equiaxed grains. The ＂ hooking＂ defects appear at the interface of overlap joints in the advancing side, which compromise significantly the load bearing capacity of joints. The elongation of joints was only 3.18% , less than 25% that of base metal. When the rotation speed was 800r/min and welding speed was 200mm/min, the ultimate strength of joints reached 467MPa, that as much as 94% of the base metal. After artificial aging, the peak tensile strength was increased to 526MPa, and there were the obvious growth in measured ultimate strength and the corresponding reduction in the elongation of joints. In addition, the tensile fracture surface analyses indicated that the tensile cracks initiated from the ＂hooking＂ defects and the fracture mode of overlap joints was quasi-cleavage and dimple composite fracture.

关 键 词：搅拌摩擦焊 铝锂合金 力学性能 微观组织 断口分析 

分 类 号：TG453.9[金属学及工艺—焊接]