Study on fatigue properties of 6061-T6 aluminum alloy laser-MIG composite welding in wide area environment

6061-T6铝合金激光-MIG复合焊广域环境下疲劳性能研究 Study on fatigue properties of 6061-T6 aluminum alloy laser-MIG composite welding in wide area environment 毛镇东 MAO Zhendong 1 first-author 韩晓辉 HAN Xiaohui 1 庞西南 PANG Xinan 2 赵旭 ZHAO Xu 2 李帅贞 LI Shuaizhen 1 中车青岛四方机车车辆股份有限公司 中车青岛四方机车车辆股份有限公司 CSR Qingdao Sifang Co.,Ltd. CSR Qingdao Sifang Co.,Ltd. 西南交通大学材料科学与工程学院 西南交通大学材料科学与工程学院 Department of Materials Science and Engine ering,Southwest Jiaotong University Department of Materials Science and Engine ering,Southwest Jiaotong University 以磁悬浮列车底架地板用6061-T6铝合金为对象,研究了6061-T6铝合金激光-MIG复合焊焊接接头在低高温(-40℃、常温、70℃)的疲劳性能,为广域环境条件下磁悬浮列车设计提供基础实验数据。结果表明:常温条件下的疲劳极限为67.1 MPa,焊缝断口具有明显的劳源区、疲劳扩展区和瞬时断裂区,疲劳扩展区存在明显的疲劳辉纹,局部存在不同族簇疲劳辉纹,瞬时断裂区有明显的韧窝结构,瞬断区为韧性断裂;低温(-40℃)条件疲劳极限为61.3 MPa,焊缝断口疲劳辉纹细而致密,存在大量的二次裂纹,焊缝韧塑性降低;高温(70℃)条件疲劳极限为56.2 MPa,焊缝疲劳断口呈现准解理断裂特征,大量脆性疲劳辉纹分布于断口且瞬断区为典型的聚集型韧窝特征。 Taking 6061-T6 aluminum alloy used in undercarriage floor of maglev train as the research object,the research is focus on the fatigue strength of 6061-T6 aluminum alloy laser-MIG composite welding joint at low-high tempera ture（-40℃,room temperature,70℃）,provide basic experimental data for maglev train design under wide environmental cond-itions. The result shows that,the fatigue limit at room temperature is 67.1 MPa,weld fracture has obvious labor source zone,fatigue expansion zone and instantaneous fracture zone;the fatigue extension zone has obvious fatigue striation,local fatigue fray of different clusters;the instantaneous fracture zone has obvious dimple structure,and the instantaneous fault zone is ductile fracture. The fatigue limit of low temperatur e（-40 ℃）condition is 61.3 MPa. The fatigue crack of the weld fracture is fine and dense,and there are a large number of secondary cracks, and the weld ductility is reduced. The fatigue limit of high temperature（70 ℃） condition is 56.2 MPa,and the fatigue fracture of weld fracture is characterized by quasi-cleavage fracture. A large number of brittle fatigue ridges are distributed in the fracture and the transient zone is a typical aggregated dimple. 6061-T6铝合金 焊接接头 广域环境 疲劳性能 6061-T6 aluminum alloy welding joint wide-area environment fatigue property TG456;U266.4 2022-03-08 1 50