Effect of Heat Treatment on Microstructure Evolution and Mechanical Properties of Selective Laser Melted Inconel 718 Alloy

ABSTRACTIn order to investigate the formation of precipitates such as MC carbides and intermetallic compounds in the friction stir welded and post-heat-treated Inconel 718 alloy, this work was carried out. Furthermore, the microstructural and mechanical properties of welds and post-heat-treated material were evaluated to identify the effect on precipitates formed during post-heat-treatment. Friction stir welding (FSW) was performed at a rotation speed of 200 rpm and welding speed of 150 mm/min; heat treatment was performed after welding at 720 °C for 8 hours in vacuum. As a result, the grain size due to FSW was notably refined from 5–20 μm in the base material to 1–3 μm in the stir zone; this was accompanied by dynamic recrystallization, which resulted in enhancements in the mechanical properties as compared to the base material. In particular, applying heat treatment after FSW led to improvements in the mechanical properties of the welds—the microhardness and tensile strength increased by more than 50% and 40% in fraction, respectively, as compared to FSW alone.

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Enhancing Mechanical Properties of the Spark Plasma Sintered Inconel 718 Alloy by Controlling the Nano-Scale Precipitations

Materials ◽

10.3390/ma12203336 ◽

2019 ◽

Vol 12 (20) ◽

pp. 3336

Author(s):

Shuaijiang Yan ◽

Yun Wang ◽

Qingxiang Wang ◽

Chengsong Zhang ◽

Dazhi Chen ◽

...

Keyword(s):

Electron Microscopy ◽

Mechanical Properties ◽

Heat Treatment ◽

Solid Solution ◽

Inconel 718 ◽

Production Efficiency ◽

Solution Treatment ◽

Inconel 718 Alloy ◽

Direct Aging ◽

Spark Plasma

The present study aimed to optimize the phase constituents and mechanical properties of the spark plasma sintered (SPS) Inconel 718 (IN718) alloy. A series of heat treatment routes were designed based on the phase relations in IN718 and performed for the optimization. The microstructure and phase compositions of the SPS IN718 alloys were examined by using X-ray diffraction (XRD), scanning electron microscopy (SEM), energy disperse spectroscopy (EDS), and transmission electron microscopy (TEM). The mechanical properties of the samples were characterized at room temperature and at 650 °C. The results showed that large amounts of γ” (Ni3Nb) and γ’ (Ni3(Al, Ti)) strengthening phases precipitated in the IN718 alloy after direct aging (DA) of the as-fabricated sample. Moreover, the mechanical properties of the DA sample were comparable to that of the best one of the solution-treated and aged counterparts. The analysis showed that the rapid sintering and solid solution treatment of the IN718 alloy were achieved simultaneously by SPS. In the case of the SPS IN718 material, the direct aging regime had the same heat treatment effect as the conventional solid solution and aging treatment. This contributes toward improving the production efficiency and reduces manufacturing costs in the actual production process.

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Effect of heat treatment on microstructure evolution of Inconel 718 alloy fabricated by selective laser melting

Journal of Alloys and Compounds ◽

10.1016/j.jallcom.2018.06.112 ◽

2018 ◽

Vol 764 ◽

pp. 639-649 ◽

Cited By ~ 45

Author(s):

Xing Li ◽

J.J. Shi ◽

C.H. Wang ◽

G.H. Cao ◽

A.M. Russell ◽

...

Keyword(s):

Heat Treatment ◽

Selective Laser Melting ◽

Microstructure Evolution ◽

Inconel 718 ◽

Laser Melting ◽

Inconel 718 Alloy

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Study of Microstructure and Mechanical Properties of As-built and Heat-treated Additive Manufactured Inconel 718 Alloy

ASEAN Journal on Science and Technology for Development ◽

10.29037/ajstd.724 ◽

2021 ◽

Vol 38 (3) ◽

Author(s):

Ajay Kumar Maurya ◽

Amit Kumar

Keyword(s):

Mechanical Properties ◽

Heat Treatment ◽

Inconel 718 ◽

Failure Modes ◽

Grain Structure ◽

Inconel 718 Alloy ◽

Laves Phases ◽

Design Data ◽

Microstructure And Mechanical Properties ◽

Heat Treated

Additive manufacturing technology is becoming popular in the industry because it allows the manufacturer to fabricate cost-effective, strong, lightweight, and complex-shaped parts directly from 3D design data as compared with the conventional manufacturing method. Inconel 718 alloy is the most demanding material in aviation as well as in the automobile industry, in terms of manufacturing high-performance parts. In this study, Inconel 718 samples were built using the direct metal laser sintering process, and standard heat treatment was performed on the samples to improve their microstructure and mechanical properties. The as-built samples exhibited good grain structure with fine laves phases, but the matrix was free from ?' and ?" phases. During the heat treatment, the strengthening phases ?' and ?" precipitated. The mechanical properties of as-built and heat-treated samples were analysed and compared. Tensile tests revealed that the direct-aged sample had the higher tensile strength compared with the other conditions, whereas the as-built samples had higher ductility. Finally, fractography and microstructure analysis were performed to measure the failure modes of tensile specimens.

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