超声无铆静力学性能强化试验与机制研究*

无铆连接是一种薄板材料连接新技术,可在无需预成孔和表面预处理情况下,实现同种、异种、多层薄板材料高效连接,但由于无铆接头静力学性能较低,极大地限制了该连接技术的推广与发展。为解决这一难题,本文选用5A06铝合金与TA1钛合金进行同种金属无铆铆接,并在此基础上进行了超声金属焊接复合实验,基于静拉伸测试和扫描电镜分析,探究超声焊对无铆接头力学性能的强化机制。试验结果表明：超声焊可有效提升无铆接头力学性能,特别是对于铝合金无铆接头；超声焊使得铝合金板塑性提高,钛合金板则得到硬化；超声焊后无铆接头的受力形式发生改变,从颈部受力变为先焊合区受力再颈部受力,这是超声焊复合强化的根本原因；超声焊可使铝合金无铆接头内部形成一定深度的固相焊,使铝合金接头力学性能得到大幅提升；TA1钛合金无铆接头内部固相焊较浅,力学性能提升相对较低。

Strengthen mechanism of static mechanical properties of ultrasonic clinched joints

Clinching is a new technology for thin-plate material connection. It can realize the efficient connection of the same, dissimilar and multi-layer thin-plate materials without pre-hole and surface pretreatment. However, due to the low mechanical performance of clinched joints, the promotion and development of this connection technology are greatly limited. In order to solve this problem, this paper selects 5A06 aluminum alloy and TA1 titanium alloy for the same metal clinching. On this basis, the ultrasonic metal welding composite experiment was carried out. Based on static tensile test and scanning electron microscope analysis, the strengthening mechanism of ultrasonic welding on the mechanical properties of clinched joints was explored. The test results show that ultrasonic welding can effectively improve the mechanical properties of clinched joints, especially for aluminum alloy riveted joints. Ultrasonic welding improves the plasticity of the aluminum alloy plate, while the titanium alloysheet is hardened. After ultrasonic welding, the stress form of the clinched joint changes, from the stress on the neck to the stress on the welding area first and then on the neck, which is the fundamental reason for the composite strengthening of ultrasonic welding. Ultrasonic welding can form a certain depth of solid-phase welding inside the aluminum alloy clinched joint, which greatly improves the mechanical properties of the aluminum alloy joint; while the internal solid-phase welding of the TA1 titanium alloy clinched joint is shallow, and the mechanical properties improvement is relatively low.