铝合金双轴肩搅拌摩擦焊接接头疲劳性能研究  

Study on the fatigue performance of biaxial-shoulder aluminum friction stir welding joints

作　　者：马国栋 张颖川 黄磊杰 金炜 MA Guodong;ZHANG Yingchuan;HUANG Leijie;JIN Wei(Locomotive&Car Research Institute,China Academy of Railway Sciences Corporation Limited,Beijing 100081,China;Beijing Zongheng Electro-Mechanical Technology Co.,Ltd.,Beijing 100094,China)

机构地区：[1]中国铁道科学研究院集团有限公司机车车辆研究所,北京100081 [2]北京纵横机电科技有限公司,北京100094

出　　处：《北京交通大学学报》2022年第4期139-147,共9页JOURNAL OF BEIJING JIAOTONG UNIVERSITY

基　　金：中国国家铁路集团有限公司科技研究开发计划项目(J2021J001)。

摘　　要：为克服现有铝合金连接手段可靠性低,外观质量差等缺点,采用双轴肩搅拌摩擦焊接新工艺对母材为6061-T6,壁厚为2.5 mm轨道交通铝合金空腔型材进行焊接,并研究了新工艺下焊接接头的疲劳特性.针对金属疲劳特性,首先在中短寿命(疲劳寿命N<2×10^(6))区利用成组法对试验数据进行处理,然后对长寿命区指定了两组循环基数(N=2×10^(6),N=10^(7))使用升降法进行数据处理,获得该工艺下焊接接头的条件疲劳极限,最后结合物理现象及数学方法删选可疑值后,根据可靠性理论,采用三参数幂函数拟合法分别求出了焊接接头在置信度γ=95%时,存活率为p=99%、95%、90%、50%的p-S-N曲线.疲劳试验结果表明:正反面接头的疲劳极限分别为69.5 MPa、85 MPa;焊接接头大多断裂在搅拌摩擦焊接的返回边处,飞边缺陷是影响接头疲劳极限的重要原因,正反面的焊接工艺是导致正反面疲劳性能产生差异的主要原因;双轴肩搅拌摩擦焊接接头比熔焊接头疲劳性能更加优异.To overcome the shortcomings of the existing aluminum alloy connection means,including low reliability and poor appearance quality,the biaxial-shoulder friction stir welding process is used to weld the aluminum alloy cavity profile for rail transit with base metal 6061-T6 and wall thickness of 2.5 mm.And the fatigue performance of the welding joints under the new process are studied.Based on the metal fatigue performance,in medium-and short-life area(N<2×10^(6)),the test data are processed by the group method,and two groups of cyclic cardinality are specified for the long-life area(N=2×10^(6),N=10^(7))using the up-down method for data processing.The conditional fatigue limit of the welding joints under this process is obtained.After screening the suspicious value based on physical phenomena and mathematical methods,according to the reliability theory and the three-parameter power function fitting method,the p-S-N curves with the survival rate of p=99%,95%,90%and 50%under the confidenceγ=95%are obtained,respectively.The fatigue test results show that the fatigue limits of the front and back joints are 69.5 Mpa and 85 Mpa,respectively.Most welding joints break at the return edge of friction stir welding.The flash defect,i.e.the welding defect,is an important cause of the joint fatigue limit.The welding process on the front and back sides is the main cause for the difference of fatigue properties on the front and back sides.The fatigue performance of biaxial-shoulder friction stir welding joints is better than that of fusion welding joints.

关 键 词：铝合金型材 双轴肩搅拌摩擦焊 疲劳性能 P-S-N曲线 

分 类 号：U269.6[机械工程—车辆工程] TH133.33[交通运输工程—载运工具运用工程]