Solid-state welding of the nanostructured ferritic alloy 14YWT using a capacitive discharge resistance welding technique

Calvin Robert Lear; Jonathan Gregory Gigax; Matthew M. Schneider; Todd Edward Steckley; Thomas J. Lienert; Stuart Andrew Maloy; Benjamin Paul Eftink

doi:10.3390/met12010023

Solid-state welding of the nanostructured ferritic alloy 14YWT using a capacitive discharge resistance welding technique

Calvin Robert Lear
, Jonathan Gregory Gigax
, Matthew M. Schneider
, Todd Edward Steckley
, Thomas J. Lienert
, Stuart Andrew Maloy
, Benjamin Paul Eftink

Research output: Contribution to journal › Article › peer-review

1 Scopus citations

Abstract

Joining nanostructured ferritic alloys (NFAs) has proved challenging, as the nano-oxides that provide superior strength, creep resistance, and radiation tolerance at high temperatures tend to agglomerate, redistribute, and coarsen during conventional fusion welding. In this study, capacitive discharge resistance welding (CDRW)—a solid-state variant of resistance welding—was used to join end caps and thin-walled cladding tubes of the NFA 14YWT. The resulting solid-state joints were found to be hermetically sealed and were characterized across the weld region using electron microscopy (macroscopic, microscopic, and nanometer scales) and nanoindentation. Microstructural evolution near the weld line was limited to narrow (~50–200 µm) thermo-mechanically affected zones (TMAZs) and to a reduction in pre-existing component textures. Dispersoid populations (i.e., nano-oxides and larger oxide particles) appeared unchanged by all but the highest energy and power CDRW condition, with this extreme producing only minor nano-oxide coarsening (~2 nm → ~5 nm Ø). Despite a minimal microstructural change, the TMAZs were found to be ~10% softer than the surrounding base material. These findings are considered in terms of past solid-state welding (SSW) efforts—cladding applications and NFA-like materials in particular—and in terms of strengthening mechanisms in NFAs and the potential impacts of localized temperature–strain conditions during SSW.

Original language	English
Article number	23
Journal	Metals
Volume	12
Issue number	1
DOIs	https://doi.org/10.3390/met12010023
State	Published - Jan 2022
Externally published	Yes

Funding

Acknowledgments: This work was supported by the U.S. Department of Energy, Office of Nuclear Energy (DOE-NE), through the Nuclear Science User Facilities (NSUF) Consolidated Innovative Nuclear Research (CINR) program and through the Los Alamos National Laboratory. Los Alamos National Laboratory is operated by Triad National Security, LLC, for the National Nuclear Security Administration of the U.S. Department of Energy (Contract No. 89233218CNA000001). This work was performed, in part, at the Center for Integrated Nanotechnologies, an Office of Science User Facility operated for the U.S. Department of Energy (DOE) Office of Science by Los Alamos National Laboratory, and at the Electron Microscopy Lab at Los Alamos National Laboratory. The authors wish to further acknowledge the efforts of D. Sornin and Y. DeCarlan of CEA-Sarclay in the pilger processing of 14YWT tubing and of L. Lindamood and J. Gould of EWI in the CDRW joining.

Keywords

Capacitive discharge resistance welding
Cladding
Nanostructured ferritic alloys
Oxide-dispersion-strengthened
Pressure resistance welding
Solid-state welding

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10.3390/met12010023

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title = "Solid-state welding of the nanostructured ferritic alloy 14YWT using a capacitive discharge resistance welding technique",

abstract = "Joining nanostructured ferritic alloys (NFAs) has proved challenging, as the nano-oxides that provide superior strength, creep resistance, and radiation tolerance at high temperatures tend to agglomerate, redistribute, and coarsen during conventional fusion welding. In this study, capacitive discharge resistance welding (CDRW)—a solid-state variant of resistance welding—was used to join end caps and thin-walled cladding tubes of the NFA 14YWT. The resulting solid-state joints were found to be hermetically sealed and were characterized across the weld region using electron microscopy (macroscopic, microscopic, and nanometer scales) and nanoindentation. Microstructural evolution near the weld line was limited to narrow (\textasciitilde{}50–200 µm) thermo-mechanically affected zones (TMAZs) and to a reduction in pre-existing component textures. Dispersoid populations (i.e., nano-oxides and larger oxide particles) appeared unchanged by all but the highest energy and power CDRW condition, with this extreme producing only minor nano-oxide coarsening (\textasciitilde{}2 nm → \textasciitilde{}5 nm {\O}). Despite a minimal microstructural change, the TMAZs were found to be \textasciitilde{}10\% softer than the surrounding base material. These findings are considered in terms of past solid-state welding (SSW) efforts—cladding applications and NFA-like materials in particular—and in terms of strengthening mechanisms in NFAs and the potential impacts of localized temperature–strain conditions during SSW.",

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AU - Lienert, Thomas J.

AU - Maloy, Stuart Andrew

AU - Eftink, Benjamin Paul

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N2 - Joining nanostructured ferritic alloys (NFAs) has proved challenging, as the nano-oxides that provide superior strength, creep resistance, and radiation tolerance at high temperatures tend to agglomerate, redistribute, and coarsen during conventional fusion welding. In this study, capacitive discharge resistance welding (CDRW)—a solid-state variant of resistance welding—was used to join end caps and thin-walled cladding tubes of the NFA 14YWT. The resulting solid-state joints were found to be hermetically sealed and were characterized across the weld region using electron microscopy (macroscopic, microscopic, and nanometer scales) and nanoindentation. Microstructural evolution near the weld line was limited to narrow (~50–200 µm) thermo-mechanically affected zones (TMAZs) and to a reduction in pre-existing component textures. Dispersoid populations (i.e., nano-oxides and larger oxide particles) appeared unchanged by all but the highest energy and power CDRW condition, with this extreme producing only minor nano-oxide coarsening (~2 nm → ~5 nm Ø). Despite a minimal microstructural change, the TMAZs were found to be ~10% softer than the surrounding base material. These findings are considered in terms of past solid-state welding (SSW) efforts—cladding applications and NFA-like materials in particular—and in terms of strengthening mechanisms in NFAs and the potential impacts of localized temperature–strain conditions during SSW.

AB - Joining nanostructured ferritic alloys (NFAs) has proved challenging, as the nano-oxides that provide superior strength, creep resistance, and radiation tolerance at high temperatures tend to agglomerate, redistribute, and coarsen during conventional fusion welding. In this study, capacitive discharge resistance welding (CDRW)—a solid-state variant of resistance welding—was used to join end caps and thin-walled cladding tubes of the NFA 14YWT. The resulting solid-state joints were found to be hermetically sealed and were characterized across the weld region using electron microscopy (macroscopic, microscopic, and nanometer scales) and nanoindentation. Microstructural evolution near the weld line was limited to narrow (~50–200 µm) thermo-mechanically affected zones (TMAZs) and to a reduction in pre-existing component textures. Dispersoid populations (i.e., nano-oxides and larger oxide particles) appeared unchanged by all but the highest energy and power CDRW condition, with this extreme producing only minor nano-oxide coarsening (~2 nm → ~5 nm Ø). Despite a minimal microstructural change, the TMAZs were found to be ~10% softer than the surrounding base material. These findings are considered in terms of past solid-state welding (SSW) efforts—cladding applications and NFA-like materials in particular—and in terms of strengthening mechanisms in NFAs and the potential impacts of localized temperature–strain conditions during SSW.

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KW - Oxide-dispersion-strengthened

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Solid-state welding of the nanostructured ferritic alloy 14YWT using a capacitive discharge resistance welding technique

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Keywords

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