Cold spray manufacturing of oxide-dispersion strengthened (ODS) steels using gas-atomized and ball-milled 14YWT powders

Hwasung Yeom, David Hoelzer, Stuart Maloy, Kumar Sridharan

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4 Scopus citations

Abstract

The cold spray deposition process has been investigated for the manufacture of 14YWT oxide-dispersion strengthened (ODS) steel, a nanostructured ferritic alloy (NFA), using gas-atomized and ball-milled feedstock powders. Cold spraying of the gas-atomized powder resulted in a thick dense deposit, but annealing them above 900 °C induced grain growth and heterogeneous precipitation of nanoparticles, thus resulting in lower hardness (∼ 170 HV) compared to 14YWT ODS steel manufactured by the conventional method. The ball-milled powder (Fe-14Cr-3W-0.4Ti-0.2Y-0.125O) was cryomilled in liquid N2 to achieve small particle sizes followed by annealing in a H2/Ar environment at 1000 °C and 1100 °C to reduce the hardness from ∼ 8 GPa to ∼ 5 GPa. Both smaller particle sizes and lower hardness of annealed powders made them amenable to the cold spray deposition process, resulting in thick and dense deposits, while retaining the favorable fully solutionized microstructure of the ball-milled powders. The microstructure of the as-deposited ODS exhibited very fine grain sizes (50–250 nm) with a uniform dispersion of Y-Ti-O nanoprecipitates in the ferritic steel matrix. The hardness values of the cold spray deposits using the powders annealed at 1000 °C and 1100 °C was 770 HV and 496 HV, respectively. Post-heat treatment of the as-deposited material up to 1100 °C showed a high-density microstructure with uniformly dispersed nanoscale oxide particles. The hardness of the annealed deposits up to 1000 °C had a notably higher hardness than bulk 14YWT ODS steel manufactured by conventional methods. The study demonstrates that cold spray deposition of the microstructurally-tailored feedstock powders can be used to successfully manufacture ODS steel with microstructure and properties comparable to those produced by the conventional methods, while providing for an attractive option for the more rapid and cost-effective manufacturing of ODS steel cladding tubes.

Original languageEnglish
Article number154187
JournalJournal of Nuclear Materials
Volume574
DOIs
StatePublished - Feb 2023

Funding

This research was supported by U.S. Department of Energy NEUP Program Grant Award DE-NE0008682. The authors would like to thank Mia Lenling, Vishnu Ramasawmy, Xinwu Liu, and Carson Lukas for their assistance in sample preparation, annealing experiments, and micro-/nano-indentation. A part of material characterization work was conducted at Idaho National Laboratory (INL) through a Nuclear Science User Facility, Rapid Turnaround Experiment (RTE) Award Number 19–2843 with support from Dr. Xiang Liu and Dr. Mukesh Bachhav.

Keywords

  • 14YWT
  • Cold spray deposition technology
  • Oxide dispersion strengthened steel
  • Powder engineering

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