电子束熔丝成形Ti6Al4V单道沉积体的工艺研究：几何尺寸、显微组织，成分及硬度

Parametric investigation on Ti6Al4V single beads produced by electron beam freeform fabrication: Geometry, microstructure, composition and hardness

摘要:

采用电子束熔丝成形工艺制备了Ti6Al4V单道沉积体，并研究了送丝速度、束流功率和行进速度等工艺参数下沉积体的几何尺寸、显微结构、成分以及硬度的变化。结果表明，加快送丝速度有利于提高沉积效率及成形精度，但需要足够的热输入以保证沉积顺利。当送丝速率、行进速度增大或束流功率减小时，由于熔池温度和尺寸的减小，可以获得较窄的柱状β晶及其内部细小的组织特征，同时铝Al蒸发损耗降低。因此，采用这些工艺制备的沉积体具有更高的硬度。本文揭示了工艺参数与沉积体工艺结果之间关系，为制造具有可靠组织结构和力学性能的多层构件提供有价值的指导。

Abstract:

Ti6Al4V single beads were prepared by electron beam freeform fabrication (EBF3) to investigate their geometry, microstructure, composition and the resulting hardness in terms of the wire-feed rate, beam power and travel speed. Results showed that an increased wire-feed rate favored to increase the deposition efficiency and geometry accuracy, but it required an affordable heat input to success in deposition. The narrowed columnar β grains filled with the fine microstructural features inside and the decreased Al evaporation loss were available at an increased wire-feed rate/travel speed or a decreased beam power, which was attributed to the decreased temperature and dimension of molten pool. Therefore, the beads produced at such process variables possess the increased hardness. This investigation reveals the correlation between the process parameters and the process outcomes of deposited beads, which offers a valuable guidance for accurate manufacturing of multi-layered components with reliable microstructure and mechanical properties.