The longstanding issue in additive manufacturing (AM) of titanium alloys is the large, columnar grains created by the intrinsic directional heat flow along the build direction. These long grains lead to strongly anisotropic mechanical properties that impede the qualification and applications of the final products. In this work, a novel in-situ rolling technique coupled with the direct energy deposition (DED) was developed to fabricate a Ti-6Al-4V alloy part. Through this hybrid technique, excellent isotropic tensile properties were achieved for thin-wall components. The strength and uniform elongation along two mutually perpendicular directions exhibited good consistency with negligible property scatter. Further studies revealed that the isotropic tensile properties were associated with the formation of nearly equiaxed prior-β grains uniformly distributed throughout the whole sample. Meanwhile, the internal α grains exhibited around 2.5 times weaker textures in the rolled compared to the unrolled DED samples. Moreover, strength increases were observed for samples produced by in-situ rolling in DED. This enhanced tensile strength was attributed to the heavily refined prior-β grains compared to those in the unrolled sample. In addition, an interface phase with a face-centred cubic structure (FCC, a = 0.43 nm) was observed between the α and β phases in both unrolled and in-situ rolled samples. The processing method in this work is applicable to other metallic materials to remove the columnar grain structures and provide improved mechanical performance.

钛合金增材制造 (AM) 中长期存在的问题是由沿构建方向的固有定向热流产生的大柱状晶粒。这些长晶粒导致强烈的各向异性机械性能，阻碍了最终产品的鉴定和应用。在这项工作中，开发了一种与直接能量沉积 (DED) 相结合的新型原位轧制技术来制造 Ti-6Al-4V 合金零件。通过这种混合技术，薄壁部件实现了优异的各向同性拉伸性能。沿两个相互垂直方向的强度和均匀伸长率表现出良好的一致性，性能分散可忽略不计。进一步的研究表明，各向同性拉伸性能与在整个样品中均匀分布的近等轴的先验β晶粒的形成有关。同时，与未轧制的 DED 样品相比，轧制后的内部 α 晶粒表现出约 2.5 倍的弱织构。此外，通过在 DED 中原位轧制生产的样品观察到强度增加。与展开样品中的那些相比，这种增强的拉伸强度归因于高度细化的prior-β 晶粒。此外，具有面心立方结构的界面相（FCC，与展开样品中的那些相比，这种增强的拉伸强度归因于高度细化的prior-β 晶粒。此外，具有面心立方结构的界面相（FCC，与展开样品中的那些相比，这种增强的拉伸强度归因于高度细化的prior-β 晶粒。此外，具有面心立方结构的界面相（FCC，a = 0.43 nm) 在展开和原位轧制样品的 α 和 β 相之间观察到。这项工作中的加工方法适用于其他金属材料，以去除柱状晶粒结构并提供更好的机械性能。