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Sreekanth, S., Hurtig, K., Joshi, S. V., Andersson, J. & Ghassemali, E. (2020). Effect of Direct Energy Deposition Process Parameters on Single-Track Deposits of Alloy 718. Metals, 10(1), 01-16, Article ID 96.
Open this publication in new window or tab >>Effect of Direct Energy Deposition Process Parameters on Single-Track Deposits of Alloy 718
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2020 (English)In: Metals, E-ISSN 2075-4701, Vol. 10, no 1, p. 01-16, article id 96Article in journal (Refereed) Published
Abstract [en]

The effect of three important process parameters, namely laser power, scanning speed and laser stand-off distance on the deposit geometry, microstructure and segregation characteristics in direct energy deposited alloy 718 specimens has been studied. Laser power and laser stand-off distance were found to notably affect the width and depth of the deposit, while the scanning speed influenced the deposit height. An increase in specific energy conditions (between 0.5 J/mm2 and 1.0 J/mm2) increased the total area of deposit yielding varied grain morphologies and precipitation behaviors which were comprehensively analyzed. A deposit comprising three distinct zones, namely the top, middle and bottom regions, categorized based on the distinct microstructural features formed on account of variation in local solidification conditions. Nb-rich eutectics preferentially segregated in the top region of the deposit (5.4–9.6% area fraction, Af) which predominantly consisted of an equiaxed grain structure, as compared to the middle (1.5–5.7% Af) and the bottom regions (2.6–4.5% Af), where columnar dendritic morphology was observed. High scan speed was more effective in reducing the area fraction of Nb-rich phases in the top and middle regions of the deposit. The <100> crystallographic direction was observed to be the preferred growth direction of columnar grains while equiaxed grains had a random orientation.

Keywords
laser metal deposition (LMD); columnar dendritic morphology; constitutional supercooling; columnar to equiaxed transition (CET); high deposition rate
National Category
Manufacturing, Surface and Joining Technology
Research subject
ENGINEERING, Manufacturing and materials engineering; Production Technology
Identifiers
urn:nbn:se:hv:diva-14922 (URN)10.3390/met10010096 (DOI)000516827800096 ()
Available from: 2020-01-29 Created: 2020-01-29 Last updated: 2020-03-27Bibliographically approved
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ORCID iD: ORCID iD iconorcid.org/0000-0001-7289-9375

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