期刊
MATERIALS & DESIGN
卷 183, 期 -, 页码 -出版社
ELSEVIER SCI LTD
DOI: 10.1016/j.matdes.2019.108157
关键词
Additive manufacturing; Nickel-base superalloy; Heat treatment; Microstructure; Tensile properties; Elevated temperature
资金
- Lloyd's Register Foundation
- University of Bristol
- TWI Ltd.
- UK Engineering and Physical Sciences Research Council (EPSRC) [EP/M019446/1]
- EPSRC [EP/M019446/1] Funding Source: UKRI
Wire thorn 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 delta phase. Tensile test results revealed that Laves and delta 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. (C) 2019 The Authors. Published by Elsevier Ltd.
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