Influence of heat treatment on the fatigue resistance of Inconel 718 fabricated by selective laser melting (SLM)
Influence of heat treatment on the fatigue resistance of Inconel 718 fabricated by selective laser melting (SLM)
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DOI：
10.1016/j.matpr.2021.02.447
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发表时间：
2021-03
期刊：
影响因子：
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通讯作者：
S. Periane;A. Duchosal;S. Vaudreuil;H. Chibane;A. Morandeau;M. Anthony Xavior;R. Leroy
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文献类型：
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作者：
S. Periane;A. Duchosal;S. Vaudreuil;H. Chibane;A. Morandeau;M. Anthony Xavior;R. Leroy
研究了热处理工艺对选择性激光熔凝(SLM)和铸轧(C&W)工艺制备的Inconel718(IN718)材料抗疲劳性能的影响。建成的SLM样品的光学图像显示了熔池层，在熔池层中可以看到胞状和柱状树枝状结构。与基准(C&W)IN718相比，SLM样品在竣工状态下的硬度值降低了约34%。对Inconel718试件在热等静压(HIP)和航空热处理(AHT)条件下进行了热处理。在热处理过程中，预制样品中累积的拉伸残余应力降低到接近于零的水平。由于热处理过程中析出物的形成和气孔率的减少，硬度值的增加几乎与参考样品的硬度值相当。为了评估疲劳极限，进行了四点弯曲疲劳试验。结果表明，由于显微组织的差异，C&W试件的疲劳极限高于SLM试件。在SLM样本中，与SLM髋部样本相比，HIP+AHTSLM在高应力水平下存活了更多的疲劳周期。这是由于在SLM热等静压样品中存在更多的孔洞作为裂纹的起始点和δ相的存在。
In this research work, the influence of heat treatment on the fatigue resistance of Inconel 718 (IN718) fabricated by selective laser melting (SLM) and cast and wrought (C&W) process route was investigated. The optical image of the as-built SLM sample shows melt pool layers, within the melt pool layers both cellular and columnar dendritic structures are visible. The hardness value of the SLM sample under as-built condition is around 34% less compared to the reference (C&W) IN718. The as-built Inconel 718 samples were heat treated under Hot Isostatic Pressing (HIP) and Aeronautic Heat Treatment (AHT) conditions. During heat treatment the tensile residual stresses accumulated in the as-built sample was reduced close to zero. The hardness value has increased nearly equal to the hardness value of the reference sample which is due to the precipitate formation and reduced porosity during heat treatment. To evaluate the fatigue limit, the four point bending fatigue tests were carried out. Results showed fatigue limit of the C&W samples is high compared to the SLM samples due to the differences in their microstructure. Within the SLM samples, the HIP + AHT SLM has survived more fatigue cycles at high stress levels compared to the SLM HIP samples. This is due to the presence of more porosity which acted as the crack initiation site and the presence of δ phase in the SLM HIP samples.