Characterization of Ni-Based Superalloy Built by Selective Laser Melting and Electron Beam Melting
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Characterization of Ni-Based Superalloy Built by Selective Laser Melting and Electron Beam Melting YEN-LING KUO, AZUSA KAMIGAICHI, and KOJI KAKEHI Alloy718 specimens built by selective laser melting (SLM) and electron beam melting (EBM) were comparatively examined. The higher cooling rate resulted in a high dislocation density and interdendritic precipitates, which brought about inferior creep properties in SLM alloys. However, a low dislocation density, distributed d precipitates and a strong h001i texture were observed in the EBM material. As a result, the creep life of the direct-aged EBM specimen approached 1100 hours and was comparable to that of conventional cast-and-wrought alloys at 650 C. https://doi.org/10.1007/s11661-018-4769-y The Minerals, Metals & Materials Society and ASM International 2018
Alloy718 is widely used in gas turbines and related aerospace applications due to its excellent mechanical properties and structural stability at elevated temperatures.[1–3] However, Alloy718 components produced by conventional processing techniques are limited in terms of their potential complexity, and thus in their operating range and efficiency.[4] Over the past decade, a variety of additive manufacturing (AM) technologies involving electron and laser beam fabrication have become increasingly attractive fabrication methods due to their having several advantages over conventional manufacturing methods, such as a large degree of design flexibility, and reductions in the lead-time and investment cost.[5–9] Although materials produced by selective laser melting (SLM) and electron beam melting (EBM) have been studied from several perspectives—e.g., in terms of their microstructure, residual stress, and mechanical properties,[10–14] little attention has been paid to comparing and contrasting between these processes with respect to a given material. In particular, EBM and SLM involve directional solidification concepts for microstructure control through the related process variables. Moreover, EBM scanning differs from SLM scanning in fundamental ways, and the cooling rate induced by highly localized heat input, energy absorption, scanning spacing, as well as pre-heat scanning and solidification rate would contribute to differences in microstructural development and in the resulting mechanical properties. Therefore, we compare an SLM alloy with an
YEN-LING KUO, AZUSA KAMIGAICHI, and KOJI KAKEHI are with the Department of Mechanical Engineering, Tokyo Metropolitan University, 1-1 Minami-osawa, Hachioji-shi, Tokyo 192-0397, Japan. Contact e-mail: [email protected] Manuscript submitted March 15, 2018.
METALLURGICAL AND MATERIALS TRANSACTIONS A
EBM alloy using a Ni-based superalloy, Alloy718. Here we discuss the associated microstructures and the resulting mechanical properties. An EOS M280 SLM machine and an Arcam A2X EBM machine were utilized to fabricate an Alloy718 cube with the dimensions 35 9 35 9 35 mm. Table I shows the elemental compositions for the EBM and SLM powders. In this study, heat-treated cast an
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