Inhomogeneity of microstructure and mechanical properties in the nugget of friction stir welded thick 7075 aluminum alloy joints  

作　　者：Yuqing Mao Liming Ke Yuhua Chen Fencheng Liu Li Xing 

机构地区：[1]National Defence Key Discipline Laboratory of Light Allay Processing Science and Technology, Nanchang Hangkong University, Nanchang 330063. China

出　　处：《Journal of Materials Science & Technology》2018年第1期228-236,共9页材料科学技术（英文版）

基　　金：supported by the National Natural Science Foundation of China(NSFC)(No.51265043 and 51265042);the Special Construction Project of Advanced Science and Technology Innovation Team of Jiangxi Province(No.20171BCB24007)

摘　　要：In this study, 20 mm thick AA7075-T6 alloy plates were joined by friction stir welding. The microstructure and mechanical properties of the nugget zone along the thickness direction from the top to the bottom was investigated. The results showed that the microstructure including the grain size, the degree of dynamic recrystallization, the misorientation angle distribution and the precipitation phase containing its size, type and content exhibited a gradient distribution along the thickness direction. The testing results of mechanical properties of the slices showed that the nugget was gradually weakened along the depth from the top to the bottom. The maximum ultimate tensile strength, yield strength and elongation of the slice in the nugget top-middle are obtained, which are 415 MPa, 255 MPa and 8.1%, respectively.In this study, 20 mm thick AA7075-T6 alloy plates were joined by friction stir welding. The microstructure and mechanical properties of the nugget zone along the thickness direction from the top to the bottom was investigated. The results showed that the microstructure including the grain size, the degree of dynamic recrystallization, the misorientation angle distribution and the precipitation phase containing its size, type and content exhibited a gradient distribution along the thickness direction. The testing results of mechanical properties of the slices showed that the nugget was gradually weakened along the depth from the top to the bottom. The maximum ultimate tensile strength, yield strength and elongation of the slice in the nugget top-middle are obtained, which are 415 MPa, 255 MPa and 8.1%, respectively.

关 键 词：AA7075 thick plate Friction stir welding Nugget Heterogeneity Microstructure Mechanical properties 

分 类 号：TG146.21[一般工业技术—材料科学与工程] TG457.11[金属学及工艺—金属材料]