Inconel 718合金增材制造与吸铸的对比分析：均匀化过程中的组织演变
A Comparative Analysis of Inconel 718 Made by Additive Manufacturing and Suction Casting: Microstructure Evolution in Homogenization
摘要：
均匀化是增材制造（AM）部件后热处理中实现均匀微观结构的关键阶段之一。在均匀化过程中，晶粒粗化可能是保留强度的问题，这需要仔细设计时间和温度。因此，适当的均匀化设计对于AM设计变得特别重要，因为加工硬化通常不再是一种选择。在这项工作中，我们发现了一个有趣的现象，在均匀化的吸铸和AM Inconel 718高温合金。通过1180°C的短期和长期等温热处理，我们观察到在吸铸合金中的异常晶粒长大，而在激光粉末床熔合（LPBF）制备的合金中的连续再结晶。均质12 h后，AM样品的晶粒尺寸保持在130 μm左右，甚至略有减小。Nb在AM合金中的均匀性被确定为NbC形成的关键因素，其进一步影响在1180°C下的再结晶动力学。多类型的位错行为进行了研究，以阐明在均匀化合金LPBF后观察到的晶粒细化。该研究为AM合金的微观组织工程提供了一条新的途径，以改善其机械性能，使其优于传统制造的合金。
英文摘要：
Homogenization is one of the critical stages in the post-heat treatment of additive manufacturing (AM) component to achieve uniform microstructure. During homogenization, grain coarsening could be an issue to reserve strength, which requires careful design of both time and temperature. Therefore, a proper design of homogenization becomes particularly important for AM design, for which work hardening is usually no longer an option. In this work, we discovered an intriguing phenomenon during homogenization of suction-cast and AM Inconel 718 superalloys. Through both short and long-term isothermal heat treatments at 1180°C, we observed an abnormal grain growth in the suction-cast alloy but continuous recrystallization in the alloy made by laser powder bed fusion (LPBF). The grain size of AM samples keeps as small as 130 μm and is even slightly reduced after homogenization for 12 hours. The homogeneity of Nb in the AM alloys is identified as the critical factor for NbC formation, which further influences the recrystallization kinetics at 1180°C. Multi-type dislocation behaviors are studied to elucidate the grain refinement observed in homogenized alloys after LPBF. This work provides a new pathway on microstructure engineering of AM alloys for improved mechanical performance superior to traditionally manufactured ones.
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