Local inhomogeneity of mechanical properties in stir zone of friction stir welded AA1050 aluminum alloy  

铝合金AA1050搅拌摩擦焊搅拌区的力学性能局部不均匀性

作　　者：Xiao-chao LIU Yun-qian ZHEN Yu-feng SUN Zhi-kang SHEN Hai-yan CHEN Wei GUO Wen-ya LI 刘小超;甄云乾;孙玉峰;申志康;陈海燕;郭伟;李文亚(西北工业大学材料学院,西安710072;西北工业大学凝固技术国家重点实验室,西安710072;陕西省摩擦焊接工程技术重点实验室,西安710072;郑州大学材料科学与工程学院,郑州450001)

机构地区：[1]School of Materials Science and Engineering,Northwestern Polytechnical University,Xi’an 710072,China [2]State Key Laboratory of Solidification Processing,Northwestern Polytechnical University,Xi’an 710072,China [3]Shaanxi Key Laboratory of Friction Welding Technologies,Xi’an 710072,China [4]School of Materials Science and Engineering,Zhengzhou University,Zhengzhou 450001,China

出　　处：《Transactions of Nonferrous Metals Society of China》2020年第9期2369-2380,共12页中国有色金属学报（英文版）

基　　金：Project(51905437)supported by the National Natural Science Foundation of China;Project(2019M653726)supported by the China Postdoctoral Science Foundation;Project(3102019QD0407)supported by the Fundamental Research Funds for the Central Universities,China。

摘　　要：The local inhomogeneity of the stir zone in friction stir welded face-centered cubic metal was investigated,which has multiple activated slip systems during plastic deformation,by selecting commercial AA1050 aluminum alloy as an ideal experimental material.The local inhomogeneity was evaluated by uniaxial tensile tests using small samples with a 1 mm gauge length.The corresponding microstructural parameters such as grain size,misorientation angle distribution,and micro-texture,were quantified by the backscattered electron diffraction technique.A comprehensive model was used to reveal the microstructure−mechanical property relationship.The experimental results showed that the uniaxial tensile property changes significantly across the weld.The maximum ultimate tensile strength(UTS)occurred in the center of the stir zone,which was 99.0 MPa.The weakest regions were located at the two sides of the stir zone.The largest difference value in UTS reached 14.9 MPa,accounting for 15%of the maximum UTS.The analysis on the structure−mechanical property relationship suggests that the micro-texture change with the location formed during the rotational material flow is the main reason for the local inhomogeneity.以铝合金AA1050为例,研究在塑性变形过程中具有多重滑移系的面心立方金属搅拌摩擦焊搅拌区的力学性能局部不均匀性。采用标距为1 mm的小试样单轴拉伸测试评估力学性能的局部不均匀性;通过电子背散射衍射技术对搅拌区内局部的晶粒尺寸、取向差角分布和微织构等结构参数进行量化;利用综合分析模型揭示显微组织和力学性能的关系。实验结果表明,局部的单轴拉伸性能沿着焊缝宽度方向发生显著变化。抗拉强度的最大值出现在搅拌区中心,达到99.0 MPa;最小值位于搅拌区的两侧。抗拉强度之间的最大差值达14.9 MPa,为抗拉强度最大值的15%。基于结构−力学性能关系的分析可知,材料旋转流动过程中形成的随位置变化的微织构是导致局部力学性能不均匀性的主要因素。

关 键 词：friction stir welding face-centered cubic metal local inhomogeneity mechanical properties MICRO-TEXTURE 

分 类 号：TG453.9[金属学及工艺—焊接]