| Abstract Scope |
This study focuses on a newly developed ultrasonically assisted (UA) gas tungsten arc based wire additive manufacturing (GTA-WAAM) process, where the ultrasonic probe is directly dipped into the local molten pool and travels behind the arc during deposition. UA-WAAM of AA7075 metal matrix nanocomposite with TiB2 nanoparticles is performed. Interacting mechanisms of deposition parameters, ultrasonic amplitude and GTAW hot-wire system are comprehensively analyzed. Overall, UA shows the capabilities of reducing porosity, restraining the formation of the inferior interlayer structures, delaying precipitates over-aging, and enhancing dispersion of nanoparticles. These improved microstructure features directly enhance mechanical properties of the UA-WAAM samples, as shown in the hardness and tensile test results. UA benefits are more significant at a lower travel speed, which allows longer UA-melt interaction time. Lastly, UA amplitude needs to be balanced to avoid severe agitation of molten pool for the most optimized results. |