Influence of dwell time on microstructure evolution and mechanical properties of dissimilar friction stir spot welded aluminum–copper metals
Influence of dwell time on microstructure evolution and mechanical properties of dissimilar friction stir spot welded aluminum–copper metals
复制标题
DOI：
10.1016/j.jmrt.2019.02.015
复制
发表时间：
2019-05
期刊：
影响因子：
--
通讯作者：
Gao-hui Li;Li Zhou;Weilu Zhou;Xiaoguo Song;Yongxian Huang
中科院分区：
文献类型：
--
作者：
Gao-hui Li;Li Zhou;Weilu Zhou;Xiaoguo Song;Yongxian Huang
采用不同停留时间的搅拌摩擦点焊 (FSSW) 生产 1060 铝-T2 铜异种搭接接头。所有接头均具有从下铜板向上挤压到上铝板的铜钩，其界面上形成金属间化合物（IMC）。增加停留时间会增加焊接过程中的热输入并促进 IMC 生长。在短停留时间下，界面的特征是断续分布的 CuAl2 层与 CuAl 相部分混合。然而，在较长的停留时间下，在界面处形成了连续的 CuAl2-CuAl-Al4Cu9 层压层。 CuAl2、CuAl和Al4Cu9的IMC形成顺序由热力学原理确定。不同区域的显微硬度差异较大。由于分散分布的 IMC 颗粒和细化的晶粒，搅拌区 (SZ) 的硬度值要高得多。具有更好拉伸性能的接头具有更高的钩子进入上铝板的深度以及在钩子界面处具有连续的IMC层。断裂路径分析结果表明，所有断裂均始于 CuAl2-CuAl 或 CuAl2-Al 界面，然后沿钩形界面处的 IMC 层延伸。当钩界面处实现强冶金结合时，SZ 中分散的 IMC 颗粒为裂纹扩展提供了替代路径。
1060 aluminum–T2 copper dissimilar lap joints were produced by friction stir spot welding (FSSW) with various dwell time. All the joints possess a Cu hook extruded upward from the lower Cu plate into the upper Al plate with intermetallic compounds (IMCs) developed on its interface. Increasing the dwell time produced an increase in the heat input during welding and promoted IMC growth. At short dwell time, the interface was characterized by the interruptedly distributed CuAl2layer partially mingled with CuAl phase. However, continuous CuAl2–CuAl–Al4Cu9laminated layer developed at the interface at longer dwell time. IMC formation sequence for CuAl2, CuAl and Al4Cu9were determined by thermodynamic principles. Microhardness was quite different in different zones. Hardness values in the stir zone (SZ) were much higher due to the dispersively distributed IMC particles and the refined grains. Joints with better tensile properties have a higher penetration depth of the hook into the upper Al plate as well as a continuous IMC layer at the hook interface. Results of fracture path analysis indicated that all the fracture initiated at the CuAl2–CuAl or CuAl2–Al interface and then extended along the IMC layer at the hook interface. The dispersed IMC particles in the SZ provided an alternative path for crack extension when strong metallurgical bonding was achieved at the hook interface.