In the pursuit of enhancing the mechanical properties of Ni-based superalloys manufactured using additive manufacturing, it is important to mitigate microstructural heterogeneities and structural flaws by optimizing the scanning strategy and post-processing. The present work investigates the influence of scan vector length on the as-printed microstructure and recrystallization behavior of Haynes 282 designed by wire arc additive manufacturing (WAAM). The lengths of the scan vectors used in this work were 25 and 100 mm. Moreover, we studied the effect of hot isostatic pressing (HIP) and subsequent aging heat treatment on the evolution of microstructure and mechanical properties. The outcomes of our study reveal that longer scan vectors induce high cooling rates, leading to a finer grain structure and accelerated recrystallization kinetics in WAAM Haynes 282. Conversely, shorter scan vectors yield coarser microstructures accompanied by stronger texture. HIP reduces the porosity to ∼1 % and is accompanied by γ' precipitation during the furnace cooling, which can be dissolved during initial aging at 1010°C and subsequently reprecipitated via secondary aging, thereby increasing the hardness. Tensile tests unveiled that those specimens subjected to HIP exhibit yield strength at par with wrought Haynes 282. This research highlights the significance of optimizing scanning strategies and post-heat treatments to tailor the microstructure and improve the mechanical properties of Haynes 282 fabricated by WAAM.

中文翻译：

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线弧增材制造及后热处理制备的 Haynes 282 的再结晶行为和机械性能

为了提高增材制造镍基高温合金的机械性能，通过优化扫描策略和后处理来减轻微观结构不均匀性和结构缺陷非常重要。目前的工作研究了扫描矢量长度对采用电弧增材制造 (WAAM) 设计的 Haynes 282 的打印微观结构和再结晶行为的影响。本工作中使用的扫描矢量的长度为 25 毫米和 100 毫米。此外，我们研究了热等静压（HIP）和随后的时效热处理对微观结构和机械性能演变的影响。我们的研究结果表明，较长的扫描矢量会导致较高的冷却速率，从而产生更细的晶粒结构并加速 WAAM Haynes 282 的再结晶动力学。相反，较短的扫描矢量会产生较粗的微观结构，并伴有更强的织构。 HIP使气孔率降低至~1%，并在炉冷过程中伴随γ'析出，在1010℃初次时效时溶解，随后通过二次时效再沉淀，从而提高硬度。拉伸测试表明，经过 HIP 处理的样品表现出与锻造 Haynes 282 相当的屈服强度。这项研究强调了优化扫描策略和后热处理以定制微观结构并提高 WAAM 制造的 Haynes 282 机械性能的重要性。