Abstract The effects of the two support structures, thin-wall tooth contact (TC) and solid-gap (SG), on the Ti-6Al-4V parts fabricated by powder bed fusion electron beam additive manufacturing were investigated. In the Y-plane of the overhang, equiaxed β′ microstructure formed initially and gradually grew into a wider columnar structure with its width about 3 times of that iRn the solid section. Fine α/α′ and β phases were identified within the β′ grains, in which the content of α′ increases from the bottom to the top of the part and α/α′ phase presents strong textures of 0 0 0 1 and 1 1 2 ¯ 0 parallel to the build-direction. In addition, more defects were observed in the overhang than the solid, especially at the interface between the solid and the overhang sections which also induced the stress concentration. Compressive residual stresses were revealed in the parts with some points showing minor tensile residual stresses. Compared to the SG part, the TC part had a lower Vickers hardness. The solid part under the SG part acted as a heat sink and enhanced heat dissipation during the manufacturing process, which affected the thermal gradient and improved the microstructures and mechanical properties in the overhang. The teeth in the TC part did limit the occurrence of the wrapping phenomenon. Taking advantages of the two designs, a new support design, SG support with teeth at the tip-end of overhang, is recommended.

中文翻译：

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支撑结构对粉末床熔融电子束增材制造Ti-6Al-4V悬垂件的影响

摘要 研究了薄壁齿接触（TC）和固体间隙（SG）两种支撑结构对粉末床熔融电子束增材制造Ti-6Al-4V零件的影响。在悬垂的Y平面上，等轴β'微结构最初形成，逐渐长大为较宽的柱状结构，其宽度约为实心截面iRn的3倍。β′晶粒内发现细小的α/α′和β相，其中α′的含量从零件的底部到顶部增加，α/α′相呈现0 0 0 1和1 1的强烈织构2 ¯ 0 平行于构建方向。此外，在悬垂部分观察到的缺陷多于固体，特别是在固体和悬垂部分之间的界面处，这也引起了应力集中。在零件中显示出压缩残余应力，其中一些点显示出较小的拉伸残余应力。与SG部分相比，TC部分的维氏硬度较低。SG 部分下方的实心部分在制造过程中充当散热器并增强散热，从而影响热梯度并改善悬垂部的微观结构和机械性能。TC部分的齿确实限制了缠绕现象的发生。结合这两种设计的优点，推荐一种新的支撑设计，在悬垂末端带有齿的SG支撑。SG 部分下方的实心部分在制造过程中充当散热器并增强散热，从而影响热梯度并改善悬垂部的微观结构和机械性能。TC部分的齿确实限制了缠绕现象的发生。结合这两种设计的优点，推荐一种新的支撑设计，在悬垂末端带有齿的SG支撑。SG 部分下方的实心部分在制造过程中充当散热器并增强散热，从而影响热梯度并改善悬垂部的微观结构和机械性能。TC部分的齿确实限制了缠绕现象的发生。结合这两种设计的优点，推荐一种新的支撑设计，在悬垂末端带有齿的SG支撑。