ABSTRACT
Dissimilar materials can be joined successfully using new and innovative industrial automotive welding techniques that require less energy, reduce cycle time and operating costs, and improve quality, among other advantages. Conventional fusion welding techniques operate above the melting point of the base material. The mechanical properties and microstructural characteristics of the joint are significantly affected by this high heat input and rapid solidification of molten metal. As a result, cracks due to shrinkage, distortion, and residual stress defects occur. These issues can be solved by the introduction of solid-state joining techniques that include the friction phenomenon. One of these solid-state joining techniques, ultrasonic spot welding (USW), is a new and emerging concept used in industry over the past 20 years and serving manufacturing sectors such as aviation, medical, microelectronics, automotive, and much more. USW is a clean and reliable technique in which the welding is done with high energy. No flux or filler metal is needed, tool life is longer, and it takes a very short time (less than one second) to weld materials in a perfectly controllable environment with better efficiency and higher mass production rate. The authors describe the fundamental concepts of the USW technique in this chapter.
