A Technique for the Quantitative Characterization of Weld Microstructure and Application to Mo Welds

Noah M. Kohlhorst, Kevin M. Faraone, Roger G. Miller, Govindarajan Muralidharan, George B. Ulrich, Ji Cheng Zhao

Research output: Contribution to journalArticlepeer-review

2 Scopus citations

Abstract

The choice of weld parameters determines the size, shape, and curvature of grains in the fusion zone (FZ) and heat-affected zone (HAZ) of welds while the mechanical properties of the welds are correlated to this microstructure. A new technique to quantitatively evaluate these microstructural characteristics in both zones of welds has been applied to molybdenum gas tungsten arc welds fabricated using different weld parameters. Trends in microstructural characteristics in the FZ and HAZ were evaluated and correlated with changes to heat input, weld speed, and weld technique. The use of this approach showed that a 20 pct decrease in heat input caused a 20 pct decrease in the number of FZ grains with aspect ratios ≥ 4. The orientations of the FZ grain segments as a function of distance from the FZ centerline were significantly affected by the weld speed and its effect on weld pool shape. A 50 pct increase in weld speed caused a 20 pct decrease in grain segments orientated 60 to 90 deg from the normal to the direction of welding. This technique also captured differences in grain sizes and grain size anisotropy in the FZ between welds made with a constant current, pulsed current, and use of a 4-pole-magnetic oscillator.

Original languageEnglish
Pages (from-to)1434-1448
Number of pages15
JournalMetallurgical and Materials Transactions B: Process Metallurgy and Materials Processing Science
Volume54
Issue number3
DOIs
StatePublished - Jun 2023

Funding

This manuscript has been authored by UT-Battelle, LLC under Contract No. DE-AC05-00OR22725 with the U.S. Department of Energy. The authors would like to acknowledge Alan Frederick, Doug Kyle for welding trials, Caitlin Duggan, Victoria Cox, and Tom Geer for metallography, Kevin Hanson and Ian Stinson for material processing and heat treatments. The authors would also like to acknowledge Glenn Romanoski, Yong Chae Lim, and Dean Pierce for their review of the manuscript. This work was funded by the National Aeronautics and Space Administration in partnership with the U.S. Department of Energy. The United States Government retains, and the publisher, by accepting the article for publication, acknowledges that the United States Government retains a non-exclusive, paid-up, irrevocable, world-wide license to publish or reproduce the published form of this manuscript, or allow others to do so, for United States Government purposes. The Department of Energy will provide public access to these results of federally sponsored research in accordance with the DOE Public Access Plan (http://energy.gov/downloads/doe-public-access-plan ). On behalf of all authors, the corresponding author states that there is no conflict of interest. This manuscript has been authored by UT-Battelle, LLC under Contract No. DE-AC05-00OR22725 with the U.S. Department of Energy. The authors would like to acknowledge Alan Frederick, Doug Kyle for welding trials, Caitlin Duggan, Victoria Cox, and Tom Geer for metallography, Kevin Hanson and Ian Stinson for material processing and heat treatments. The authors would also like to acknowledge Glenn Romanoski, Yong Chae Lim, and Dean Pierce for their review of the manuscript. This work was funded by the National Aeronautics and Space Administration in partnership with the U.S. Department of Energy. The United States Government retains, and the publisher, by accepting the article for publication, acknowledges that the United States Government retains a non-exclusive, paid-up, irrevocable, world-wide license to publish or reproduce the published form of this manuscript, or allow others to do so, for United States Government purposes. The Department of Energy will provide public access to these results of federally sponsored research in accordance with the DOE Public Access Plan ( http://energy.gov/downloads/doe-public-access-plan ).

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