The influence of Laves phases on the room temperature tensile properties of Inconel 718 fabricated by powder feeding laser additive manufacturing
The influence of Laves phases on the room temperature tensile properties of Inconel 718 fabricated by powder feeding laser additive manufacturing
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DOI：
10.1016/j.actamat.2018.10.032
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发表时间：
2019-02-01
期刊：
影响因子：
9.4
通讯作者：
Huang, Weidong
中科院分区：
文献类型：
--
作者：
Sui, Shang;Tan, Hua;Huang, Weidong
本文采用送粉激光附加制造技术制备了Inconel718高温合金。用三种不同的热处理方法获得了不同尺寸和形貌的Laves相。研究了Laves相对激光添加剂制造的Inconel718合金室温拉伸性能的影响。结果表明，S-15样品经1050℃热处理15min后，可获得细小的颗粒状Laves相。当保温时间延长到45min时，Laves相的形态基本保持不变，但其体积分数进一步下降(S-45样品)。然而，直接时效处理后的样品(DA样品)仍然存在不规则的长条状Laves相。室温拉伸结果表明，S-15试件比S-45试件具有更好的抗拉强度和塑性。此外，具有不规则Laves相和长条纹状Laves相的DA样品的抗拉强度和塑性最低。因此，一定数量的细小颗粒状Laves相可能有利于Inconel718的室温拉伸性能。此外，还建立了描述Laves相断裂的模型。根据断裂模型，长条Laves相断裂所需的临界应力低于粒状Laves相断裂所需的临界应力。因此，前者通常会发生内部骨折，而后者往往会因界面解粘而失效。通过影响γ‘相的体积分数、尺寸和分布，实现了Laves相对室温拉伸性能的影响。此外，还建立了屈服强度模型，从数值上揭示了这种影响。三种样品由颗粒、固溶元素和伽马‘相引起的屈服强度增量基本相同。屈服强度的差异主要是由伽马‘相引起的。此外，在塑性方面，颗粒状Laves相比长条状Laves相更有利。(C)2018 Acta Materialia Inc.由Elsevier Ltd.出版。保留所有权利。
In this paper, a powder feeding laser additive manufacturing technology has been used for fabricating the Inconel 718 super-alloy. Laves phases of different sizes and morphologies have been obtained by using three types of heat treatments. The influence of Laves phases on the room temperature tensile properties of laser additive manufactured Inconel 718 has been investigated. The results show that small and granular Laves phase can be gained after heat treatment at 1050 degrees C for 15 min (S-15 sample). When the holding time extends to 45 min, the morphologies of Laves phases basically remain unchanged while its volume fraction further decreases (S-45 sample). Nevertheless, irregular and long-striped Laves phases still exist in the samples only after direct aging heat treatment (DA sample). The room temperature tensile results reveal that the S-15 samples have better tensile strength and ductility than that of S-45 samples. Besides, the DA samples with irregular and long-striped Laves phases show the lowest tensile strength and ductility. Hence, a certain amount of small and granular Laves phases are presumably beneficial for the room temperature tensile properties of Inconel 718. Moreover, a model has been established to describe the fracture of the Laves phase. On the basis of the fracture model, the critical stress needed for the fracture of long-striped Laves phases is lower than that needed for the fracture of granular Laves phases. Therefore, the former generally suffered internal fracture while the latter often fail by interfacial decohesion. Through influencing the volume fraction, the size and the distribution of gamma '' phase, the effect of the Laves phases on the room temperature tensile property is achieved. Furthermore, a yield strength model has been developed to reveal this influence in terms of numbers. The yield strength increments caused by grains, solution elements and gamma' phase are almost the same for the three kinds of samples. The differences of the yield strength are mainly caused by gamma '' phase. In addition, in terms of ductility, granular Laves phases are more favorable than long-striped Laves phases. (C) 2018 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.