2A12/6061异种铝合金TIG搭接接头的疲劳性能  

Fatigue properties of 2A12/6061 dissimilar aluminum alloy TIG welded lap joints

作　　者：赵平林 王瑞杰[1] 刘国寿[2] 廖祥雲 ZHAO Ping-lin;WANG Rui-jie;LIU Guo-shou;LIAO Xiang-yun(School of Mechanical and Electrical Engineering,Kunming University of Technology,Kunming 650500,China;Faculty of Civil Engineering and Mechanics,Kunming University of Technology,Kunming 650500,China)

机构地区：[1]昆明理工大学机电工程学院 [2]昆明理工大学建筑工程学院

出　　处：《材料热处理学报》2024年第2期195-203,共9页Transactions of Materials and Heat Treatment

基　　金：国家自然科学基金(51065012)。

摘　　要：对3 mm厚的2A12/6061异种铝合金板材进行搭接钨极惰性气体保护焊(TIG),利用光学显微镜、显微硬度仪、扫描电镜和疲劳实验机等对接头的疲劳性能进行分析。在实验结果的基础上,对搭接试样建立有限元模型,采用热点应力法预测接头的疲劳寿命,并与实验结果进行比较。结果表明:焊缝区组织为均匀的等轴晶,2A12侧焊缝与母材熔合较差,且与母材强度差异较大,导致2A12侧焊趾处更容易产生冶金缺陷和较大的应力梯度,进而加速疲劳裂纹的萌生;在不同载荷水平下,试件断裂位置均位于强度差异较大的2A12侧焊趾处,呈脆-塑性复合断裂特征,焊趾处冶金缺陷及焊缝局部强度差异为影响接头疲劳性能的主要因素。寿命预测结果表明:采用考虑板厚效应的热点应力法预测寿命准确,误差在两倍误差带内,采用IIW推荐的FAT40 S-N曲线是安全可靠的。Tungsten inert gas(TIG) welding was conducted on 3 mm thick 2A12/6061 dissimilar aluminum alloy plates,and the fatigue performance of the joints was analyzed using optical microscope,microhardness tester,scanning electron microscopy and fatigue testing machine.Based on the experimental results,a finite element model was established for the lap joint specimen,and the fatigue life of the joint was predicted using the hot spot stress method and compared with the experimental results.The results show that the microstructure of the weld zone is uniform equiaxed grains,and the fusion between the 2A12 side weld and the base metal is poor,with a significant difference in strength,resulting in metallurgical defects and large stress gradients at the 2A12 side weld toe,thereby accelerating the initiation of fatigue cracks.Under different load levels,the fracture location of the specimen is located at the 2A12 side weld toe with significant strength differences,exhibiting a brittle-plastic complex fracture characteristics.Metallurgical defects at the weld toe and local strength differences in the weld are the main factors that affect the fatigue performance of the joint.The fatigue life prediction results indicate that the hot spot stress method considering the plate thickness effect is accurate,with an error within a double error band.The FAT40 S-N curve recommended by IIW is considered safe and reliable.

关 键 词：异种铝合金 TIG焊 疲劳强度 热点应力法 疲劳寿命 

分 类 号：TG444[金属学及工艺—焊接]