Article

Metallurgical and Materials Transactions A

, Volume 42, Issue 11, pp 3491-3508

First online:

Open Access This content is freely available online to anyone, anywhere at any time.

Microstructural Architecture, Microstructures, and Mechanical Properties for a Nickel-Base Superalloy Fabricated by Electron Beam Melting

  • L. E. MurrAffiliated withDepartment of Metallurgical and Materials Engineering, The University of Texas at El Paso Email author 
  • , E. MartinezAffiliated withDepartment of Metallurgical and Materials Engineering, The University of Texas at El Paso
  • , S. M. GaytanAffiliated withDepartment of Metallurgical and Materials Engineering, The University of Texas at El Paso
  • , D. A. RamirezAffiliated withDepartment of Metallurgical and Materials Engineering, The University of Texas at El Paso
  • , B. I. MachadoAffiliated withDepartment of Metallurgical and Materials Engineering, The University of Texas at El Paso
  • , P. W. ShindoAffiliated withDepartment of Metallurgical and Materials Engineering, The University of Texas at El Paso
  • , J. L. MartinezAffiliated withDepartment of Metallurgical and Materials Engineering, The University of Texas at El Paso
  • , F. MedinaAffiliated withW.M. Keck Center for 3D Innovation, The University of Texas at El Paso
  • , J. WootenAffiliated withCalRAM, Inc.
    • , D. CiscelAffiliated withCalRAM, Inc.
    • , U. AckelidAffiliated withArcam AB
    • , R. B. WickerAffiliated withW.M. Keck Center for 3D Innovation, The University of Texas at El Paso

Abstract

Microstructures and a microstructural, columnar architecture as well as mechanical behavior of as-fabricated and processed INCONEL alloy 625 components produced by additive manufacturing using electron beam melting (EBM) of prealloyed precursor powder are examined in this study. As-fabricated and hot-isostatically pressed (“hipped”) [at 1393 K (1120 °C)] cylinders examined by optical metallography (OM), scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy-dispersive (X-ray) spectrometry (EDS), and X-ray diffraction (XRD) exhibited an initial EBM-developed γ″ (bct) Ni3Nb precipitate platelet columnar architecture within columnar [200] textured γ (fcc) Ni-Cr grains aligned in the cylinder axis, parallel to the EBM build direction. Upon annealing at 1393 K (1120 °C) (hot-isostatic press (HIP)), these precipitate columns dissolve and the columnar, γ, grains recrystallized forming generally equiaxed grains (with coherent {111} annealing twins), containing NbCr2 laves precipitates. Microindentation hardnesses decreased from ~2.7 to ~2.2 GPa following hot-isostatic pressing (“hipping”), and the corresponding engineering (0.2 pct) offset yield stress decreased from 0.41 to 0.33 GPa, while the UTS increased from 0.75 to 0.77 GPa. However, the corresponding elongation increased from 44 to 69 pct for the hipped components.