[T6] AM Beam Based Technologies

[15B-T6-18] Microstructure and Mechanical Properties of Additive-Manufactured Alloy 718 Fabricated by Electron Beam - Powder Bed Fusion (EB-PBF)

*A. Morishige¹, T. N. Palleda¹, K. Kakehi¹, A. Miyakita², K. Masuda², T. Sato² (1.Tokyo Metropolitan University, Japan, 2.JEOL, Japan)

キーワード：EB-PBF, Alloy718, columnar, equiaxed, creep properties

It is difficult to build additive-manufactured material by setting manufacturing parameters with the intention of controlling the microstructure because parameters are automatically assigned at the time of manufacturing in the widely used overseas EB-PBF (electron beam powder bed fusion). Therefore, we fabricated an additive manufacturing of Alloy718 with a characteristic microstructure using the JEOL EB-PBF, which can perform additive manufacturing by setting manufacturing parameters, and investigated the microstructure and high-temperature mechanical properties. The columnar grain structure with <100> orientation and the fine equiaxed grain structures were obtained. Creep test at 650°C/550 MPa showed that both STA (solution treatment and aged) specimens had longer creep life than the cast & wrought (C&W) specimen. In the high-temperature tensile test, grain boundary fracture, which was presumably caused by misoriented crystal grains, was observed, suggesting that it is important to suppress the formation of misoriented crystal grains during the manufacturing process.