Augmented Laser Impact Welding: A New Process Demonstration in Welding Aluminum Alloy 2024-T3

Laser-shock processes, including laser impact welding, are limited by the amount of optical energy that can be transmitted to a workpiece. This new process, Augmented Laser Impact Welding, makes use of an explosive chemical mixture to augment the amount of energy available in a typical Laser Impact Welding experiment. This chemical mixture consists of only two components, nitromethane and smokeless gunpowder. This chemical mixture detonates upon illumination by laser power densities of 1.58 GW/cm2 or greater. Upon detonation, the energy released allows for acceleration of 0.5 mm thick aluminum 2024-T3 flyers to speeds in excess of 750 m/s. The experimental parameters which produce these high velocities are characterized in this work. Impact welding of the same 2024-T3 flyers by use of this process is also demonstrated, and the tensile strength of the impact welds are measured. The impact welds compared well with similar riveted joints. These impact welded joints between 2024-T3 aluminum show promise for creating strong bonds in this difficult to join material system. Further, the driving system can be easily implemented for efficient, inexpensive, and robust solid-state impact welding. This paper represents the first reported use of laser and chemical augmentation to drive impact-based welds.