Stability of Microstructure in Al3003 Builds Made by Very High Power Ultrasonic Additive Manufacturing
Abstract
Very High Power Ultrasonic Additive Manufacturing (VHP-UAM) system was used to
produce aluminum parts from 150 µm thick Al3003-H18 foils. The build was processed at 36 μm
vibration amplitude, 8 kN normal load, and 35.6 mm/s weld speed at 20 kHz frequency. Almost
100% linear weld density was achieved. A deformation-interaction volume of ~20 μm was
observed below the bonded interface. The microstructural stability including grain boundary
structures, and crystallographic orientations was evaluated after annealing these samples at
343oC for 2 hours and 450oC for 2 hours. After heat treatment, small grains persisted at the
interfaces with sluggish grain growth kinetics. In contrast, normal grain growth kinetics was
observed in the middle of the foils. Possible mechanisms for such phenomena are discussed.