Remelting and bonding of deposited aluminum alloy droplets under different droplet and substrate temperatures in metal droplet deposition manufacture

Direct fabrication of unsupported inclined aluminum pillars based on uniform micro droplets deposition

“…In the low frequency range, the stable and controllable columnar morphology can be kept in the deposition of inclined pillar [4,5]. The low frequency range is confirmed as 0~23.25Hz by equation (16).…”

“…2 w r   (5) where r is the droplet radius. 8 δ is defined as fusion ratio, which is the ratio of melting height h and the droplet diameter, as described in equation (6).…”

“…In this technique, 3D object can be fabricated through a highly flexible "digital fabrication" process [4,5]. At present, these parts are mostly two-dimensional structure [6,7].…”

“…Re-melting between impinging droplet and previous droplet could be considered as an one-dimensional Stefan problem with phase change [14,19,24], where the thermal and dynamic behaviors of molten metal droplets belong to non-isothermal deposition [25]. Less re-melting and poor metallurgical bonding under inappropriate droplet temperature or substrate temperature will result in micro-void and cold lap [5,26].…”

Effects of substrate preheating on the thin-wall part built by laser metal deposition shaping

“…They performed the related tests and analyses to the 3D SLM rectangular samples fabricated with preheating temperature of 500 • C, but not concentrated on the effects of varied preheating temperatures on the samples; Fallah et al [13] studied the impact of localized surface preheating on the microstructure and crack formation in laser direct deposited sample, but their the conclusions neglected the influence rules of different preheating temperatures. Chao et al [14] address the appropriate combination of droplet and substrate temperatures through the related numerical model and deposition experiments, so they can improve the interior quality of deposited aluminum alloy parts with appropriate temperature condition by removing some common defects. Nevertheless, they were not concerned with the effects of substrate on the microstructure and performances of formed components.…”