9 research outputs found
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Stability of Microstructure in Al3003 Builds Made by Very High Power Ultrasonic Additive Manufacturing
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.Mechanical Engineerin
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Bond Characterization in Very High Power Ultrasonic Additive Manufacturing
Solid parts were produced by Very High Power Ultrasonic Additive Manufacturing (VHP-UAM)
at room temperature using 150 μm thick tapes of 6061 aluminum and 110 copper alloys.
Processing was done at 20 kHz frequency over a range of parameters (26 –36 μm vibration
amplitude, 5.6 – 6.7 kN normal force, and 30.5 - 35.5 mm/s travel speed). Softening of materials
(up to about 14% in 6061 Al and 23% in 110 Cu) was noted facilitating enhanced plastic flow
and a reduction in interfacial voids. Evolution of fine recrystallized grains (0.3-4 μm in 6061 Al
and 0.3-10 μm in 110 Cu) from an initial coarser grain structure (up to 8 μm in 6061 Al and 25
μm in Cu) was observed at the build interface regions. Bonding between layers in both materials
seems to have occurred by dynamic recrystallization and movement of grain boundaries across
the interface. The energy required for the above physical processes is derived from interfacial
adiabatic plastic deformation heating.Mechanical Engineerin