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Solid-State Welding of the Nanostructured Ferritic Alloy 14YWT Using a Capacitive Discharge Resistance Welding Technique

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

Metals 2022, 12(1), 23; https://doi.org/10.3390/met12010023 - 23 Dec 2021

Cited by 1 | Viewed by 3057

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. Full article

(This article belongs to the Special Issue Advanced Alloys for Nuclear Applications)

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12 pages, 5802 KiB

Open AccessArticle

Stress Corrosion Cracking Threshold for Dissimilar Capacitive Discharge Welding Joint with Varied Surface Geometry

by Darmadi B. Djarot, Femiana Gapsari, Osmar Buntu Lobo and Firman Mangasa Simanjuntak

Appl. Sci. 2020, 10(6), 2180; https://doi.org/10.3390/app10062180 - 23 Mar 2020

Cited by 6 | Viewed by 4452

Abstract

Stress corrosion cracking (SCC) is known as a major factor that should be considered in the assessment of welding joint structure integrity. Despite the promising and wide application of dissimilar metal joints, the currently available SCC mitigation technique of dissimilar metal joints is not adequate. The challenge is to obtain a good joint while different melting points exist. This article reports a novel SCC mitigation method on a brass–steel dissimilar metal joint by modifying the geometry of the surface. It is evidenced that the sharpened steel (α1 specimen) significantly improves the SCC resilience of the joint. The evaluation of SEM/EDS photos reveals that the α1 geometry induces a smaller pore area around brass–steel micro-joint interfaces which in turn produces stronger joints. Full article

(This article belongs to the Section Nanotechnology and Applied Nanosciences)

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