Functionally Graded Porous Scaffolds (FGPS) manufactured from Ti and Ti alloys such as Ti6Al4V is an attractive candidate for mimicking host bone tissue. Porous specimens manufactured by powder-bed fusion additive manufacturing (PBF-AM) methods always contain some amount of powder attached to the surfaces of the outer or the inner parts. Powder removal is an important issue for the porous structures with high relative density designed for biomedical applications. In some cases, traditional powder removal methods such as standard powder recovery systems (PRS) become ineffective. Chemical and electrochemical etching is one of the possible solutions for effective residual powder removal from PBF-AM structures.

Traditional single-stage HF/HNO₃ chemical etching protocols of the Ti6Al4V often leads to the overetching of the periphery of the porous samples leaving inner parts untouched. The aim of present research was to determine if fractionated chemical etching of porous Ti6Al4V Functionally Graded Porous Scaffolds (FGPS) with multiple immersions could facilitate trapped powder removal and reduction the surface roughness without critical degradation of the mechanical properties. Protocols with different number and time of immersions were studied. Mechanical properties and fracture modes of as manufactured and chemically etched Ti6Al4V FGPS were investigated. Results clearly illustrate that fractionating of the etching times have positive effect. It is possible to achieve more uniform etching of the thin structures at the periphery and inside porous structures, facilitate removal of the powder particles attached to the surfaces, and removal of the powder trapped inside the structures without serious degradation of the mechanical properties.

由 Ti 和 Ti 合金（如 Ti6Al4V）制造的功能分级多孔支架 (FGPS) 是模仿宿主骨组织的有吸引力的候选者。通过粉末床熔融增材制造 (PBF-AM) 方法制造的多孔样品总是含有一定量的粉末，这些粉末附着在外部或内部部件的表面上。对于专为生物医学应用设计的具有高相对密度的多孔结构，除粉是一个重要问题。在某些情况下，标准粉末回收系统 (PRS) 等传统的粉末去除方法变得无效。化学和电化学蚀刻是从 PBF-AM 结构中有效去除残留粉末的可能解决方案之一。

传统的单级 HF/HNO ₃Ti6Al4V 的化学蚀刻协议通常会导致多孔样品外围的过度蚀刻，而内部部分却没有受到影响。本研究的目的是确定多孔 Ti6Al4V 功能梯度多孔支架 (FGPS) 的多次浸渍的分步化学蚀刻是否可以促进捕获的粉末去除并降低表面粗糙度，而不会严重降低机械性能。研究了具有不同浸泡次数和时间的方案。研究了制造和化学蚀刻的 Ti6Al4V FGPS 的机械性能和断裂模式。结果清楚地表明，蚀刻时间的分级具有积极影响。可以在多孔结构的外围和内部实现更均匀的薄结构蚀刻，