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Structure, texture and phases in 3D printed IN718 alloy subjected to homogenization and HIP treatments

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Mostafa, Ahmad, Rubio, Ignacio Picazo, Brailovski, Vladimir, Jahazi, Mohammad et Medraj, Mamoun. 2017. « Structure, texture and phases in 3D printed IN718 alloy subjected to homogenization and HIP treatments ». Metals, vol. 7, nº 6.
Compte des citations dans Scopus : 30.

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Abstract

3D printing results in anisotropy in the microstructure and mechanical properties. The focus of this study is to investigate the structure, texture and phase evolution of the as-printed and heat treated IN718 superalloy. Cylindrical specimens, printed by powder-bed additive manufacturing technique, were subjected to two post-treatments: homogenization (1100 °C, 1 h, furnace cooling) and hot isostatic pressing (HIP) (1160 °C, 100 MPa, 4 h, furnace cooling). The Selective laser melting (SLM) printed microstructure exhibited a columnar architecture, parallel to the building direction, due to the heat flow towards negative z-direction. Whereas, a unique structural morphology was observed in the x-y plane due to different cooling rates resulting from laser beam overlapping. Post-processing treatments reorganized the columnar structure of a strong {002} texture into fine columnar and/or equiaxed grains of random orientations. Equiaxed structure of about 150 µm average grain size, was achieved after homogenization and HIP treatments. Both δ-phase and MC-type brittle carbides, having rough morphologies, were formed at the grain boundaries. Delta-phase formed due to γ″-phase dissolution in the γ matrix, while MC-type carbides nucleates grew by diffusion of solute atoms. The presence of (Nb0.78Ti0.22)C carbide phase, with an fcc structure having a lattice parameter a = 4.43 Å, was revealed using Energy dispersive spectrometer (EDS) and X-ray diffractometer (XRD) analysis. The solidification behavior of IN718 alloy was described to elucidate the evolution of different phases during selective laser melting and post-processing heat treatments of IN718.

Item Type: Peer reviewed article published in a journal
Professor:
Professor
Brailovski, Vladimir
Jahazi, Mohammad
Affiliation: Génie mécanique, Génie mécanique
Date Deposited: 26 Jun 2017 18:05
Last Modified: 05 Oct 2018 15:41
URI: http://espace2.etsmtl.ca/id/eprint/15497

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