Mechanical properties and microstructure revolution of vibration assisted wire arc additive manufacturing 2319 aluminum alloy.

In this study, a hybrid wire arc additive manufacturing (HWAAM) process that combines low-frequency vibration with cold metal transfer (CMT) arc is proposed to address the problems of porosity, coarse grains, and low mechanical performance encountered in WAAM aluminum alloys. The effects of different vibration frequencies on the microstructure and mechanical properties were investigated. The results indicated that as the vibration frequency increases, the grain size refinement reaches a maximum of 19.1% compared with the non-vibrated specimen. Vibration can enhance the fluidity and the cooling rate of the weld pool. The fatigue fracture of dendrite arms is the main mechanism of microstructure grain refinement caused by vibration. The dynamic bending stress induced by vibration on the dendrite arms and the root remelting phenomenon are the dominant factors for the dendrite fragmentation. Increasing the vibration frequency did not result in an obvious improvement in the tensile strength of the specimens, but did significantly increase the elongation. With the increase in vibration frequency, the maximum transverse and longitudinal elongation reached 22.2% and 23.5% respectively, a raise of 15.6% and 38.2% compared with non-vibrated specimen. Vibration reduced the size and distribution density of pores on the fracture surface, and increased the dimpled microstructure, improving the mechanical performance of the aluminum alloy. [ABSTRACT FROM AUTHOR]