摘要
目的研究2.5 mm厚的7050-T74511铝合金回填式搅拌摩擦点焊工艺参数,焊点组织与力学性能之间的关系。方法通过显微组织观察和断口扫描,分析接头形貌特征和缺陷对断裂模式的影响。通过拉伸剪切测试,分析工艺参数与力学性能之间的关系。采用三因素三水平BBD响应面法进行工艺优化,建立拉剪失效载荷与工艺参数之间的二阶响应模型并求得最优工艺。结果工艺优化的最佳参数为扎入深度2.7 mm,焊具转速为1500 r/min,焊接时间为8 s,在此参数下接头拉剪失效载荷为8.294 kN。当焊接工艺参数选择恰当时,可得到无缺陷接头。结论焊接工艺窗口较窄;在高热输入条件下(扎入深度3.1 mm,转速2100 r/min)易产生孔洞、弱连接等缺陷,且这些缺陷主要分布在搅拌区与热力影响区界面上;在低热输入条件下(扎入深度2.7 mm,转速1500 r/min),接头拉剪载荷较高,这与焊点在低热输入情况下组织缺陷较少有关。
This article aims to study the relationship among process parameters, microstructures and properties of refill friction stir spot welded joint of 2.5 mm-thick 7050-T74511 aluminium alloy. Microstructure observation and fracture scanning were carried out to analyze the influence of joint morphology and defects on fracture modes. The relationship between the processing parameters and the mechanical properties was analyzed through tensile shear test. We had process parameters optimization containing 3 factors and 3 levels through Box-Behnken Design and built up the two stage response model to obtain the optimum process. Through solving the model, we obtained the optimized parameters as follows: the plunge depth was 2.7 mm, the rotation speed was 1500 r/min, the joining time was 8 s, and the corresponding tensile shear failure load was 8.294 kN. The results showed that it could obtain none defects weld when choosing proper process parameters. The process window is quite narrow, imperfection such as voids, incomplete mix occur easily when the heat input is high(plunge depth is 3.1 mm and rotation speed is 2100 r/min). These defects are always located at the SZ/TMAZ interface. The joint has higher failure load when the heat input is lower(plunge depth is 2.7 mm and rotation speed is 1500 r/min), which is related to the few microstructure imperfection in this situation.
作者
豆建新
熊江涛
陈丹
张浩楠
孙静茹
赵华夏
DOU Jian-xin;XIONG Jiang-tao;CHEN Dan;ZHANG Hao-nan;SUN Jing-ru;ZHAO Hua-xia(Shaanxi Key Laboratory of Friction Welding Technologies,State Key Laboratory of Solidification Processing,School of Materials Science and Engineering,Northwestern Polytechnical University,Xi'an 710072,China;AVIC Manufacture Technology Institute,Beijing 100024,China)
出处
《精密成形工程》
2019年第6期81-88,共8页
Journal of Netshape Forming Engineering
