Research Papers

Correlation Between Microstructure and Mechanical Properties in an Inconel 718 Deposit Produced Via Electron Beam Freeform Fabrication

[+] Author and Article Information
Wesley A. Tayon

NASA Langley Research Center,
Hampton, VA 23681
e-mail: wesley.a.tayon@nasa.gov

Ravi N. Shenoy

Northrop Grumman,
Technical Services
Hampton, VA 23681

MacKenzie R. Redding

Engineering Physics Department,
University of Virginia,
Charlottesville, VA 22904

R. Keith Bird, Robert A. Hafley

NASA Langley Research Center,
Hampton, VA 23681

1Corresponding author.

Contributed by the Manufacturing Engineering Division of ASME for publication in the JOURNAL OF MANUFACTURING SCIENCE AND ENGINEERING. Manuscript received April 8, 2014; final manuscript received September 2, 2014; published online October 24, 2014. Assoc. Editor: Joseph Beaman.

This material is declared a work of the US Government and is not subject to copyright protection in the United States. Approved for public release; distribution is unlimited.

J. Manuf. Sci. Eng 136(6), 061005 (Oct 24, 2014) (7 pages) Paper No: MANU-14-1152; doi: 10.1115/1.4028509 History: Received April 08, 2014; Revised September 02, 2014

Electron beam freeform fabrication (EBF3), a metallic layer-additive manufacturing process, uses a high-power electron beam in conjunction with a metal feed wire to create a molten pool on a substrate, which on solidification produces a component of the desired configuration made of sequentially deposited layers. During the build-up of each solidified layer, the substrate is translated with respect to the electron beam and the feed wire. EBF3 products are similar to conventional cast products with regard to the as-deposited (AD) microstructure and typical mechanical properties. Inconel 718 (IN 718), a high-temperature superalloy with attractive mechanical and oxidation properties well suited for aerospace applications, is typically used in the wrought form. The present study examines the evolution of microstructure, crystallographic texture, and mechanical properties of a block of IN 718 fabricated via the EBF3 process. Specimens extracted out of this block, both in the AD and in a subsequently heat treated (HT) condition, were subjected to (1) microstructural characterization using scanning electron microscopy (SEM); (2) in-plane elastic modulus, tensile strength, and microhardness evaluations; and (3) crystallographic texture characterization using electron backscatter diffraction (EBSD). Salient conclusions stemming from this study are: (1) mechanical properties of the EBF3-processed IN 718 block are strongly affected by texture as evidenced by their dependence on orientation relative to the EBF3 fabrication direction, with the AD EBF3 properties generally being significantly reduced compared to wrought IN 718; (2) significant improvement in both strength and modulus of the EBF3 product to levels nearly equal to those for wrought IN 718 may be achieved through heat treatment.

Copyright © 2014 by ASME
Your Session has timed out. Please sign back in to continue.


Taminger, K., and Hafley, R., 2006, Electron Beam Freeform Fabrication (EBF3) for Cost Effective Near-Net Shape Manufacturing, NASA Technical Memorandum Paper No. TM-2006-214284.
Taminger, K., and Hafley, R., 2003, “Electron Beam Freeform Fabrication: A Rapid Metal Deposition Process,” 3rd Annual Automotive Composites Conference, Troy, MI, Sept. 9–10, Society of Plastics Engineers, Troy, MI.
Brown, W. F., and Setlak, S., eds., 2005, Aerospace Structural Metals Handbook, CINDAS/USAF CRDA Handbook Operation, Purdue University, West Lafayette, IN.
Bird, R. K., and Hibberd, J., 2009, “Tensile Properties and Microstructure of Inconel 718 Fabricated With Electron Beam Freeform Fabrication (EBF3),” NASA Technical Memorandum Paper No. TM-2009-215929.
Reed, R., 2006, The Superalloys: Fundamentals and Applications, Cambridge University Press, Cambridge, UK. [CrossRef]
Bi, G., Sun, C.-N., Chen, H.-C., Ng, F. L., and Ma, C. C. K., 2014, “Microstructure and Tensile Properties of Superalloy IN100 Fabricated by Micro-Laser Aided Additive Manufacturing,” Mater. Des., 60, pp. 401–408. [CrossRef]
Antonysamy, A. A., Meyer, J., and Prangnell, P. B., 2013, “Effect of Build Geometry on the β-Grain Structure and Texture in Additive Manufacture of Ti6Al4V by Selective Electron Beam Melting,” Mater. Charact., 84, pp. 153–168. [CrossRef]
Thijs, L., Montero Sistiaga, M. L., Wauthle, R., Xie, Q., Kruth, J.-P., and Van Humbeeck, J., 2013, “Strong Morphological and Crystallographic Texture and Resulting Yield Strength Anisotropy in Selective Laser Melted Tantalum,” Acta Mater., 61(12), pp. 4657–4668. [CrossRef]
Edwards, P., O'Conner, A., and Ramulu, M., 2013, “Electron Beam Additive Manufacturing of Titanium Components: Properties and Performance,” ASME J. Manuf. Sci. Eng., 135(6), p. 061016. [CrossRef]
Designation E8: Tension Testing of Metallic Materials, 2010, Annual Book of ASTM Standards, Vol. 3.01, American Society for Testing and Materials, West Conshohocken, PA.
Designation E111-97: Standard Test Methods for Tension Testing of Metallic Materials, 2010, Annual Book of ASTM Standards, Vol. 3.01, American Society for Testing and Materials, West Conshohocken, PA.
Vander Voort, G. F., 1984, Metallography, Principles and Practice, McGraw-Hill, New York.
Taylor, G. I., 1938, “Plastic Strain in Metals,” J Inst. Met., 62, pp. 307–324.
Bunge, H. J., Kiewel, R., Reinert, T., and Fritsche, L., 2000, “Elastic Properties of Polycrystals—Influence of Texture and Stereology,” J. Mech. Phys. Solids, 48(1), pp. 29–66. [CrossRef]
Bishop, J. F. W., and Hill, R., 1951, “A Theory of the Plastic Distortion of a Polycrystalline Aggregate Under Combined Stresses,” Phil. Mag., 42(327), pp. 414–427.
Voigt, W., 1910, Lehrbuch der Kristallphysik, Teubner, Berlin.
Reuss, A., 1926, “Berechnung der Fließgrenze von Mischkristallen auf Grund der Plastizitätsbedingungen für Einkristalle,” Z. Angew. Math. Mech., 9(1), pp. 49–58. [CrossRef]
Holden, T. M., Holt, R. A., and Clarke, A. P., 1998, “Intergranular Strains in Inconel-600 and the Impact on Interpreting Stress Fields in Bent Steam-Generator Tubing,” Mater. Sci. Eng. A, 246(1–2), pp. 180–198. [CrossRef]
Dupond, O., Feuilly, N., Chassignole, B., Fouquet, T., Moysan, J., and Corneloup, G., 2011, “Relation Between Ultrasonic Scattering and Microstructure of Polycrystalline Materials,” J. Phys., 269(1), p. 012014. [CrossRef]
Ruff, P. E., 1986, “Effect of Manufacturing Processes on Structural Allowables—Phase I,” Air Force Wright Aeronautical Laboratories, Technical Report No. AFWAL-TR-85-4128.
U.S. Department of Defense, 1999, Military Handbook—MIL-HDBK-5H: Metallic Materials and Elements for Aerospace Vehicle Structures, Washington, DC.
Doherty, R. D., Hughes, D. A., Humphreys, F. J., Jonas, J. J., Jensen, D. J., Kassner, M. E., King, W. E., McNelley, T. R., McQueen, H. J., and Rollett, A. D., 1997, “Current Issues in Recrystallization: A Review,” Mater. Sci. Eng. A, 238(2), pp. 219–274. [CrossRef]


Grahic Jump Location
Fig. 1

The IN 718 EBF3 block (AD condition) showing tensile specimen orientations L, T, and 45 deg in the L–T plane

Grahic Jump Location
Fig. 2

Back-scattered SEM image of the dendritic microstructure in the S–T plane of the IN 718 EBF3 block (AD condition)

Grahic Jump Location
Fig. 3

Microhardness (Knoop hardness number) evaluation of crystal anisotropy in the L–T plane in various conditions of IN 718

Grahic Jump Location
Fig. 4

L-axis inverse pole figure microstructural map for IN 718 base plate with colors referenced to stereographic triangle. Thin black lines denote high-angle grain boundaries.

Grahic Jump Location
Fig. 5

Inverse pole figure maps for IN 718 EBF3 block (AD condition), referenced to direction L (top) and direction T (bottom). Thin black lines denote high-angle grain boundaries. The legends apply to both maps.

Grahic Jump Location
Fig. 6

001, 011, and 111 pole figures for the IN 718 EBF3 block in the AD condition

Grahic Jump Location
Fig. 7

Elastic modulus maps for the L (top) and T (bottom) directions for IN 718 EBF3 block in the AD condition

Grahic Jump Location
Fig. 8

In-plane (L–T) variations in EBSD-computed elastic modulus for the AD IN 718 EBF3 block

Grahic Jump Location
Fig. 9

In-plane (L–T) variations in average Taylor factor in the AD IN 718 EBF3 block

Grahic Jump Location
Fig. 10

L-axis inverse pole figure map in IN 718 EBF3 block in the HT condition

Grahic Jump Location
Fig. 11

001, 011, and 111 pole figures for IN 718 EBF3 block (HT condition). The contours are scaled to match with the pole figures for the AD EBF3 condition in Fig. 6.

Grahic Jump Location
Fig. 12

Variation in EBSD-computed elastic modulus for the IN 718 EBF3 block (HT condition)

Grahic Jump Location
Fig. 13

Variations in average Taylor factor for the IN 718 EBF3 block (HT condition)



Some tools below are only available to our subscribers or users with an online account.

Related Content

Customize your page view by dragging and repositioning the boxes below.

Related Journal Articles
Related eBook Content
Topic Collections

Sorry! You do not have access to this content. For assistance or to subscribe, please contact us:

  • TELEPHONE: 1-800-843-2763 (Toll-free in the USA)
  • EMAIL: asmedigitalcollection@asme.org
Sign In