Thermal Transients During Processing of 3003 Al-H18 Multilayer Build by Very High-Power Ultrasonic Additive Manufacturing

Previous investigations suggested a gradient in bond microstructure along the height of a “build” made by very high power ultrasonic additive manufacturing—a rapid prototyping process that is based on ultrasonic seam welding. The bonding of foils is associated with the occurrence of dynamic recrystallization at the interfaces between them. To understand heating patterns across the build that may be responsible for such microstructure evolution, temperatures from different interface regions were recorded simultaneously during the fabrication of a 3003 Al-H18 multilayer build under a given processing condition. Thermal transients were observed over multiple interfaces of the build during welding of each layer. The temperatures were the highest for the layer processed and were found to diminish beneath with each subsequent layer. Such maximum temperatures also depended on the height at which the new layer was bonded. The occurrence of transients across the build is rationalized based on heat being conducted away from the processed layer.