Torsional Behavior of Additively Manufactured Nickel Alloy 718 under Monotonic Loading and Low Cycle Fatigue
Document Type
Article
Publication Date
9-2020
Abstract
The high weldability and corrosion resistance of nickel alloy 718 (IN718) make it an ideal material for laser powder-bed fusion (LPBF). However, many of its material properties are still not characterized. Monotonic torsion and low cycle torsional fatigue tests were performed on LPBF IN718 in order to determine its shear properties. Three different print orientations (horizontal, diagonal, vertical) and three separate heat treatments (none, AMS-5662, modified) were tested to determine their effects on the LPBF IN718's torsional behavior. The modified heat treatment was developed to reduce LPBF IN718's anisotropic nature. Monotonic torsion tests revealed that the ultimate shear strength (USS) and yield shear strength (YSS) were dependent on both print orientation and heat treatment, while the shear modulus (G) was only dependent on the print orientation. The USS and YSS improved by at least 42% and 68%, respectively, when either heat treatment was applied. The vertical specimens had the highest G in all cases. The modified heat treatment reduced the difference between the maximum and minimum USS and G from approximately 29% and 38% to approximately 6% and 9%, respectively. The fatigue life appears to be more influenced by the print orientation than the heat treatment. In every case, the horizontal and vertical specimens had the highest and lowest fatigue lives, respectively. Fracture surface analysis revealed similar features observed in conventionally-manufactured material. These results indicate that both the print orientation and the heat treatment must be considered when designing LPBF IN718 parts that will be subjected to torsional loads.
Source Publication
Materials Today Communications (eISSN 2352-4928)
Recommended Citation
Sabelkin, V. P., Cobb, G. R., Doane, B. M., Kemnitz, R. A., & O’Hara, R. P. (2020). Torsional behavior of additively manufactured nickel alloy 718 under monotonic loading and low cycle fatigue. Materials Today Communications, 24(OA-AM-link), 101256. https://doi.org/10.1016/j.mtcomm.2020.101256
Comments
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