GOALI/Collaborative Research: Fundamental Research on Impact Welding of Aluminum and Steel

GOALI学术联络合作研究奖支持对一种新兴焊接技术--冲击焊接--的基础研究，以加入原本难以加入的材料组合。研究将集中在铝-钢焊接上，因为连接这些金属有各种各样和重要的商业需求。这两种贱金属都有很好的特性，发展坚固的铝-钢接头可以减轻汽车的质量。更轻的汽车消耗更少的燃料，向大气中排放更少的碳。研究成果将使该技术在汽车、航空航天、医疗器械等重要行业得到更广泛的应用。传统的焊接工艺会熔化待连接的两种金属，熔融混合可能会导致脆性金属间化合物，使接头不适合大多数结构应用。冲击焊缝可以是坚固而坚韧的，通过两个金属表面之间的高速(通常为200-700米/S)斜碰撞在固态下产生。本研究的目的是：1)了解飞片厚度(因此其总动能)如何影响形成的界面结构；2)了解冲击焊接过程中界面应变、温度和形态的实时演变；3)将变形历史与最终的焊缝组织和性能联系起来。独特的工具被用来研究从25微米到25毫米厚度的铝-钢的冲击。激光冲击焊接和爆炸焊接分别用于最薄和最厚的飞片，而汽化箔致动器焊接将用于加速几个中等厚度的飞片。光子多普勒测速仪将能够对碰撞速度和角度进行详细测量。基于光滑粒子流体力学和任意拉格朗日-欧拉方法的有限元模型将被发展用于这些问题。它们的有效性将通过焊接结构的金相检查和与模拟的比较来检验。这些模型将被用来理解材料应变、温度和结构在广泛的长度尺度上的复杂动态发展。

This Grant Opportunity for Academic Liaison with Industry (GOALI) collaborative research award supports fundamental research on an emerging welding technology - impact welding - to join material combinations that are otherwise difficult to join. Research will focus on aluminum-steel welds because there are diverse and important commercial needs in joining these metals. Both base metals are well characterized and the development of robust aluminum-steel unions can reduce automobile mass. Lighter cars use less fuel and emit less carbon to the atmosphere. Research results will enable wider application of this technology in important industries including automotive, aerospace, and medical devices. Traditional welding processes melt both metals to be joined and the molten mixing can result in brittle intermetallic compounds, rendering the joints unsuitable for most structural applications. Impact welds can be strong and tough and are created in the solid state by a high-speed (typically 200-700 m/s) oblique collision between two metal surfaces. The objectives of this research are: 1) to understand how the thickness of the flyer plate (and therefore its total kinetic energy) affects the structure of the interface that is formed, 2) to understand the real-time evolution of strain, temperature and morphology of the interface during the impact welding process and 3) relate the deformation history to the final structure and properties of the weld. Unique tools are used to study aluminum-steel impacts from flyer thicknesses of 25 µm to 25 mm. Laser impact welding and explosive welding are used for the thinnest and thickest flyers, respectively, while vaporizing foil actuator welding will be used to accelerate flyers of several intermediate thicknesses. Photonic Doppler velocimetry will enable detailed measurements of collision speed and angle. Finite element models based on Smoothed Particle Hydrodynamics and Arbitrary Lagrangian-Eulerian methods will be developed for these problems. Their validity will be tested by metallographic examination of welded structures and comparison of these to simulation. These models will be used to understand the complex dynamic development of material strains, temperatures and structures and on a wide range of length scales.