On the toughness scatter in low alloy C-Mn steel samples fabricated using wire arc additive manufacturing

Niyanth Sridharan, Mark W. Noakes, Andrzej Nycz, Lonnie J. Love, Ryan R. Dehoff, Sudarsanam S. Babu

Research output: Contribution to journalArticlepeer-review

59 Scopus citations

Abstract

Low alloy carbon manganese (C-Mn) steel builds were fabricated using a wire based additive manufacturing system developed at Oak Ridge National Laboratory. Specimens were fabricated in the X,Y and Z direction and detailed mechanical testing was performed. The mechanical testing results showed a significant scatter in tensile ductility and significant variation in Charpy toughness. Further detailed microstructure characterization showed significant microstructural heterogeneity in builds fabricated in each direction. The scatter in mechanical properties was then rationalized based on the microstructural observations and the underlying changes in the local heat transfer conditions. The results indicate that when fabricating parts using C-Mn low alloy steel welds the process parameters and tool path should be chosen such that the cooling rate from 800 °C to 500 °C is greater than 30 s to avoid formation of martensite austenite (MA) phases, which leads to toughness reductions.

Original languageEnglish
Pages (from-to)18-27
Number of pages10
JournalMaterials Science and Engineering: A
Volume713
DOIs
StatePublished - Jan 24 2018

Funding

This manuscript has been authored by UT-Battelle, LLC , under Contract No. DE-AC05-00OR22725 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, worldwide 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 ). Research was sponsored by the U.S. Department of Energy, Office of Energy Efficiency and Renewable Energy, Advanced Manufacturing Office, under contract DE-AC05-00OR22725 with UT Battelle, LLC. This research at the Oak Ridge National Laboratory's High Temperature Materials Laboratory was sponsored by the U. S. Department of Energy, Office of Energy Efficiency and Renewable Energy, Vehicle Technologies Program. The authors wish to acknowledge the contributions of Thomas Geer of ORNL for assistance with sample preparation for microscopy analysis.

Keywords

  • Additive manufacturing
  • Characterization
  • Mechanical properties
  • Steel

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