Abstract To achieve improved microstructure and mechanical properties, an innovative wire arc additive manufacturing (WAAM) process with forced interpass cooling using compressed CO2 was employed in this study to fabricate Ti6Al4V thin-walled structures. The effects of various interpass temperatures and rapid forced cooling on deposition geometry, surface oxidation, microstructural evolution, and mechanical properties of the fabricated part were investigated by laser profilometry, optical microscopy (OM), scanning electron microscopy (SEM), hardness testing and mechanical tensile testing. Results show that the microstructural evolution and mechanical properties of the deposited metal are not greatly affected by an increasing interpass temperature, however, the deposited wall tends to be widened, flattened and exhibit increased surface oxidation through visible coloration. When rapid forced cooling using CO2 is used between deposited layers, slightly higher hardness values and increased strength can be obtained. This is mainly attributed to the combined effects of less surface oxide and high density dislocation caused by the generation of large amounts of fine-grained acicular α within the microstructure. Furthermore, forced interpass cooling not only improves deposition properties, but also promotes geometrical repeatability and also improved manufacturing efficiency through the reduction of dwell time between deposited layers.

中文翻译：

---

层间强制冷却对电弧增材Ti6Al4V合金材料性能的影响

摘要 为了改善微观结构和机械性能，本研究采用创新的电弧增材制造 (WAAM) 工艺，采用压缩 CO2 强制层间冷却，制造 Ti6Al4V 薄壁结构。通过激光轮廓仪、光学显微镜 (OM)、扫描电子显微镜 (SEM)、硬度测试和机械性能研究了各种层间温度和快速强制冷却对制造零件的沉积几何形状、表面氧化、微观结构演变和机械性能的影响。拉伸试验。结果表明，层间温度升高对熔敷金属的显微组织演变和力学性能影响不大，但熔敷壁趋于加宽，通过可见的着色变平并表现出增加的表面氧化。当在沉积层之间使用 CO2 进行快速强制冷却时，可以获得稍高的硬度值和更高的强度。这主要是由于微观结构内产生大量细晶针状α导致的表面氧化物较少和高密度位错的综合影响。此外，强制层间冷却不仅可以提高沉积性能，还可以通过减少沉积层之间的停留时间来提高几何可重复性并提高制造效率。这主要是由于微观结构内产生大量细晶针状α导致的表面氧化物较少和高密度位错的综合影响。此外，强制层间冷却不仅可以提高沉积性能，还可以通过减少沉积层之间的停留时间来提高几何可重复性并提高制造效率。这主要是由于微观结构内产生大量细晶针状α导致的表面氧化物较少和高密度位错的综合影响。此外，强制层间冷却不仅可以提高沉积性能，还可以通过减少沉积层之间的停留时间来提高几何可重复性并提高制造效率。