Wire + Arc Additively Manufactured Inconel 718: Effect of post-deposition heat treatments on microstructure and tensile properties
Wire + Arc Additive Manufacturing (WAAM) can be used to create large free-form components out of specialist materials such as nickel-base superalloys. Inconel (IN) 718 is well suited for the WAAM process due to its excellent weldability. However, during deposition, WAAM IN718 is susceptible to micro...
| Main Authors: | , , , , , |
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| Format: | Article |
| Language: | English |
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Elsevier
2019-12-01
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| Series: | Materials & Design |
| Online Access: | http://www.sciencedirect.com/science/article/pii/S0264127519305957 |
| _version_ | 1818941154053324800 |
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| author | Cui E. Seow Harry E. Coules Guiyi Wu Raja H.U. Khan Xiangfang Xu Stewart Williams |
| author_facet | Cui E. Seow Harry E. Coules Guiyi Wu Raja H.U. Khan Xiangfang Xu Stewart Williams |
| author_sort | Cui E. Seow |
| collection | DOAJ |
| description | Wire + Arc Additive Manufacturing (WAAM) can be used to create large free-form components out of specialist materials such as nickel-base superalloys. Inconel (IN) 718 is well suited for the WAAM process due to its excellent weldability. However, during deposition, WAAM IN718 is susceptible to micro-segregation, leading to undesirable Laves phase formation in the interdendritic regions. Further, the WAAM process encourages columnar grain growth and the development of a strong fibre texture, leading to anisotropy in grain structure. This unfavourable microstructure can be addressed through specialised post-deposition homogenisation heat treatments. A new modified heat treatment was found to be effective in dissolving Laves phase, whereas a standard treatment precipitated δ phase. Tensile test results revealed that Laves and δ phases lead to low ductility when present in a precipitation-hardened matrix. The modified heat treatment also reduced the anisotropy in grain structure, leading to almost isotropic elevated temperature tensile properties, which meet minimum specifications for conventional cast but not for wrought material. Specialised post-deposition heat treatments, which address the unique microstructure of WAAM IN718, are crucial to achieving optimal mechanical properties. Keywords: Additive manufacturing, Nickel-base superalloy, Heat treatment, Microstructure, Tensile properties, Elevated temperature |
| first_indexed | 2024-12-20T06:51:01Z |
| format | Article |
| id | doaj.art-f1852bfb938a448492cb609bf35a9a7f |
| institution | Directory Open Access Journal |
| issn | 0264-1275 |
| language | English |
| last_indexed | 2024-12-20T06:51:01Z |
| publishDate | 2019-12-01 |
| publisher | Elsevier |
| record_format | Article |
| series | Materials & Design |
| spelling | doaj.art-f1852bfb938a448492cb609bf35a9a7f2022-12-21T19:49:33ZengElsevierMaterials & Design0264-12752019-12-01183Wire + Arc Additively Manufactured Inconel 718: Effect of post-deposition heat treatments on microstructure and tensile propertiesCui E. Seow0Harry E. Coules1Guiyi Wu2Raja H.U. Khan3Xiangfang Xu4Stewart Williams5Department of Mechanical Engineering, University of Bristol, Bristol, BS8 1TR, UK; NSIRC, TWI Ltd, Granta Park, Great Abington, Cambridge, CB21 6AL, UK; Corresponding author.Department of Mechanical Engineering, University of Bristol, Bristol, BS8 1TR, UKTWI Ltd, Granta Park, Cambridge, CB21 6AL, UKTWI Ltd, Granta Park, Cambridge, CB21 6AL, UKWelding Engineering and Laser Processing Centre, Cranfield University, Cranfield, MK43 0AL, UKWelding Engineering and Laser Processing Centre, Cranfield University, Cranfield, MK43 0AL, UKWire + Arc Additive Manufacturing (WAAM) can be used to create large free-form components out of specialist materials such as nickel-base superalloys. Inconel (IN) 718 is well suited for the WAAM process due to its excellent weldability. However, during deposition, WAAM IN718 is susceptible to micro-segregation, leading to undesirable Laves phase formation in the interdendritic regions. Further, the WAAM process encourages columnar grain growth and the development of a strong fibre texture, leading to anisotropy in grain structure. This unfavourable microstructure can be addressed through specialised post-deposition homogenisation heat treatments. A new modified heat treatment was found to be effective in dissolving Laves phase, whereas a standard treatment precipitated δ phase. Tensile test results revealed that Laves and δ phases lead to low ductility when present in a precipitation-hardened matrix. The modified heat treatment also reduced the anisotropy in grain structure, leading to almost isotropic elevated temperature tensile properties, which meet minimum specifications for conventional cast but not for wrought material. Specialised post-deposition heat treatments, which address the unique microstructure of WAAM IN718, are crucial to achieving optimal mechanical properties. Keywords: Additive manufacturing, Nickel-base superalloy, Heat treatment, Microstructure, Tensile properties, Elevated temperaturehttp://www.sciencedirect.com/science/article/pii/S0264127519305957 |
| spellingShingle | Cui E. Seow Harry E. Coules Guiyi Wu Raja H.U. Khan Xiangfang Xu Stewart Williams Wire + Arc Additively Manufactured Inconel 718: Effect of post-deposition heat treatments on microstructure and tensile properties Materials & Design |
| title | Wire + Arc Additively Manufactured Inconel 718: Effect of post-deposition heat treatments on microstructure and tensile properties |
| title_full | Wire + Arc Additively Manufactured Inconel 718: Effect of post-deposition heat treatments on microstructure and tensile properties |
| title_fullStr | Wire + Arc Additively Manufactured Inconel 718: Effect of post-deposition heat treatments on microstructure and tensile properties |
| title_full_unstemmed | Wire + Arc Additively Manufactured Inconel 718: Effect of post-deposition heat treatments on microstructure and tensile properties |
| title_short | Wire + Arc Additively Manufactured Inconel 718: Effect of post-deposition heat treatments on microstructure and tensile properties |
| title_sort | wire arc additively manufactured inconel 718 effect of post deposition heat treatments on microstructure and tensile properties |
| url | http://www.sciencedirect.com/science/article/pii/S0264127519305957 |
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