On the microstructural and mechanical properties of post-treated additively manufactured Inconel 718 superalloy under quasi-static and cyclic loading
On the microstructural and mechanical properties of post-treated additively manufactured Inconel 718 superalloy under quasi-static and cyclic loading
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DOI：
10.1016/j.msea.2016.05.089
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发表时间：
2016-07-04
期刊：
影响因子：
6.4
通讯作者：
Niendorf, T.
中科院分区：
文献类型：
--
作者：
Aydinoez, M. E.;Brenne, F.;Niendorf, T.
Inconel 718试样通过选择性激光熔化（SLM）增材制造，并进行不同的后处理热处理。在室温（RT）下，在低周疲劳（LCF）制度的单调和循环载荷下的性能进行了研究。采用热等静压（HIP）以减少SLM后通常存在的孔隙率。应用具有通过阴极电弧沉积（Arc-PVD）施加的Ni-20 Cr涂层的先前功能封装以实现完全致密化。结果表明，经过电弧PVD和HIP后，力学性能不仅受到孔隙率降低的影响，而且还受到微观结构变化的影响。已存在于竣工状态下的结晶体（即Laves相）可通过固溶热处理溶解。热等静压导致再结晶，从而显着改变微观组织外观。通过HIP消除了SLM处理产生的细长晶粒和亚微米尺寸的单元结构。时效导致强化γ相的演变。同时，δ相在HIP和老化后形成。与未进行HIP的老化条件相比，HIP和老化后的微观结构在单调载荷下提高了延展性，但同时也降低了RT的疲劳性能。（C）2016 Elsevier B. V.版权所有。
Inconel 718 specimens were additively manufactured via selective laser melting (SLM) and subjected to different post-process heat treatments. Performance under monotonic and cyclic loading in the low-cycle fatigue (LCF) regime was investigated at room temperature (RT). Hot isostatic pressing (HIP) was employed in order to reduce the porosity typically present after SLM. Prior functional encapsulation with a Ni-20Cr coating applied by cathodic arc deposition (Arc-PVD) was applied to achieve full densification. The results show that after Arc-PVD and HIP, the mechanical properties are not only affected by reduced porosity but also by substantial microstructural changes. Precipitates, i.e. Laves phase, already present in the as-built condition can be dissolved by solution heat treatment. HIP leads to recrystallization and thus significantly changes microstructural appearance. Elongated grains and sub-micron sized cell structures stemming from SLM processing are eliminated by HIP. Aging leads to evolution of strengthening gamma '' precipitates. Concurrently, delta phase forms upon HIP and aging. In comparison to aged conditions that were not subjected to HIP, microstructure upon HIP and aging results in improved ductility under monotonic loading, however, concomitantly deteriorates fatigue properties at RT. (C) 2016 Elsevier B.V. All rights reserved.