轴向拉力对铝合金拉拔式摩擦塞焊接头组织及力学性能的影响  

Influence of Axial Force on the Microstructure and Mechanical Properties of 2A70 Aluminum Alloy Friction Pull Plug Welding

作　　者：邵震 崔雷[1,2] 王东坡[1,2] 杨君 高彦军 SHAO Zhen;CUI Lei;WANG Dongpo;YANG Jun;GAO Yanjun(School of Materials Science and Engineering,Tianjin University,Tianjin 300350;Tianjin Key Laboratory of Advanced Joining Technology,Tianjin University,Tianjin 300350;Capital Aerospace Machinery Co.,Ltd.,Beijing 100076)

机构地区：[1]天津大学材料科学与工程学院,天津300350 [2]天津大学天津市现代连接技术重点实验室,天津300350 [3]首都航天机械有限公司,北京100076

出　　处：《机械工程学报》2021年第20期117-125,共9页Journal of Mechanical Engineering

基　　金：国家自然科学基金资助项目(51875401,52075376)。

摘　　要：拉拔式摩擦塞补焊是一种固相连接技术,具有接头强度高,焊后残余应力和变形小等优点,在航天领域具有潜在的应用前景。研究轴向拉力对2A70铝合金拉拔式摩擦塞焊焊接成形及接头性能的影响,并分析焊接缺陷、微观组织及断口形貌特征。结果表明,轴向拉力在20~30 kN范围内能够得到良好的焊缝成形;轴向拉力为20 kN时,结合界面存在未焊合缺陷;轴向拉力提高至22 kN及以上,未焊合缺陷完全消除;轴向拉力提高至28~30 kN时,塞棒与母材形成完好的冶金结合,焊接接头的抗拉强度可达到376 MPa,接头系数为83.6%。当轴向拉力较低时(22~25 kN),结合界面上易出现弱结合缺陷,微观特征为沿结合界面断续分布的微孔,可导致接头抗拉强度和断后伸长率下降;焊接接头中,塞棒侧热影响区硬度值最低,分析表明该区域的晶粒形态和尺寸未发生明显变化,但θ’相部分溶解,θ相发生粗化,导致局部强度下降;断口形貌显示,在优化参数下断口呈现韧性特征。研究结果可为铝合金拉拔式摩擦塞补焊工艺及机理分析提供借鉴和参考价值。Friction pull plug welding is a kind of solid phase joining technique, which has obvious advantages, such as high strength of welding joint, small residual stress and distortion. Friction pull plug welding has a potential application for aerospace field. The influence of axial force on the forming and joint properties of 2 A70 aluminum alloy friction pull plug welding is studied. The welding defects, microstructure and fracture morphology are analyzed. The results show that good weld forming can be obtained with axial force in the range of 20-30 kN. When the axial force is 20 kN, the lack of bonding can be observed on the bonding interface. When the axial force is increased to 22 kN or above, the lack of bonding is completely eliminated. And the axial force is increased to 28-30 kN, the tensile strength of the welded joint can reach 376 MPa and the joint coefficient is 83.6%. When the axial force is low(20 kN),the bonding interface has weak bonding defects. The microscopic characteristic is micropores along the interface. The weak bonding defects are important reason for the tensile strength and elongation decline. In the welding joint, the hardness of the heat affected zone on the side of the plug is the lowest, and the analysis show that the morphology and size of the grain don’t change significantly, while the θ’ phase dissolves and the θ phase coarsens, leading to a decrease of local strength. The fracture morphology shows that the fracture has toughness characteristics under the optimized parameters. The research can provide a good reference for the analysis of the welding process and mechanism of aluminum alloy friction pull plug welding.

关 键 词：铝合金 拉拔式摩擦塞焊 轴向拉力 微观组织 力学性能 

分 类 号：TG156[金属学及工艺—热处理]