The effect of high strain rate deformation on intermetallic reaction during ultrasonic welding aluminium to magnesium
The effect of high strain rate deformation on intermetallic reaction during ultrasonic welding aluminium to magnesium
复制标题
DOI：
10.1016/j.msea.2012.06.055
复制
发表时间：
2012-10-30
期刊：
影响因子：
6.4
通讯作者：
Prangnell, P. B.
中科院分区：
文献类型：
--
作者：
Panteli, A.;Robson, J. D.;Prangnell, P. B.
高功率超声波点焊（USW）是一种低热量输入的固态连接工艺，可以为焊接不同材料对（如汽车车身应用中的镁（Mg）和铝（Al））提供解决方案。然而，高应变速率的动态变形加速了不同节理间的扩散速率。研究了Al、AA6111和Mg AZ31合金之间的界面反应与焊接能量的关系。在600J （0.4 s）的最佳焊接条件下，反应层厚度已接近5 μ m厚。在极短的焊接时间内，金属间反应中心在微焊缝界面处形核，并迅速扩散和生长，形成由Al12Mg17和Al3Mg2两个子层组成的连续层。在Al-Mg二元体系中，当温度低于公认的最低共晶反应温度时，界面液化也会延长焊接时间。模拟表明，固体反应动力学是在静态测试条件下获得的速率常数所作的抛物线生长预测的两倍以上。讨论了产生这种差异的原因和熔融反应的抑制。(c) 2012 Elsevier B.V.版权所有
High power ultrasonic spot welding (USW) is a low heat input solid-state joining process that may offer a solution for welding difficult dissimilar-material couples, like magnesium (Mg) to aluminium (Al) for automotive body applications. However, the high strain rate dynamic deformation in USW has been claimed to accelerate inter-diffusion rates in dissimilar joints. The interfacial reaction between Al, AA6111, and Mg AZ31 alloys has been studied as a function of welding energy. For the optimum welding condition of 600J (0.4 s) the reaction layer thickness was already similar to 5 mu m thick. Intermetallic reaction centres were found to nucleate within microwelds at the interface at very short welding times and spread and grow rapidly to form a continuous layer, composed of two sub-layers of Al12Mg17 and Al3Mg2. Interface liquation was also found for longer welding times at temperatures below the recognised lowest eutectic reaction temperature in the Al-Mg binary system. Modelling has been used to show that the solid state reaction kinetics were over twice the rate expected from parabolic growth predictions made using rate constants obtained under static test conditions. The reasons for this discrepancy and the depressed melting reaction are discussed. (c) 2012 Elsevier B.V. All rights reserved.