Suppression of Helium Induced Cracking in Laser Repair Welding of Highly Irradiated Stainless Steels

Jian Chen; Jonathan Tatman; Zhili Feng; Roger Miller; Stephanie Curlin; Tao Dai; Keyou Mao; Benjamin Sutton; Greg Frederick

doi:10.1016/j.jnucmat.2021.153206

Suppression of Helium Induced Cracking in Laser Repair Welding of Highly Irradiated Stainless Steels

Jian Chen, Jonathan Tatman, Zhili Feng, Roger Miller, Stephanie Curlin, Tao Dai, Keyou Mao, Benjamin Sutton, Greg Frederick

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

3 Scopus citations

Abstract

Welding repair of irradiated nuclear reactor materials such as austenitic stainless steels used for the reactor internals has been challenging due to irradiation generated helium in the material matrix over an extended period of time. In this study, improved laser welding techniques, including the novel Auxiliary Beam Stress Improved (ABSI) technique that proactively manages the stresses during laser repair welding is investigated to substantially reduce or avoid the occurrence of intergranular helium-induced cracking (HeIC). Laser weld cladding, with and without ABSI technique, was applied to deposit weld metal on irradiated stainless steel (Type 304 L) blocks with various helium concentrations up to approximately 20 atomic parts per million (appm). Welded samples were cross-sectioned and analyzed using optical and electron microscopes. It was found that, with the improved laser welding techniques, no macroscopic (millimeter-sized) cracks were observed in any of the samples. Microscopic (less than 50 μm) cracks were present in the heat affected zone. Statistical analysis on the sample with the highest helium concentration (~20 appm) reveals that the ABSI technique could effectively reduce the size and amounts of microscopic cracks.

Original language	English
Article number	153206
Journal	Journal of Nuclear Materials
Volume	556
DOIs	https://doi.org/10.1016/j.jnucmat.2021.153206
State	Published - Dec 1 2021

Bibliographical note

Publisher Copyright:
© 2021

Funding

This research was sponsored by the U.S. Department of Energy (DOE), Office of Nuclear Energy - Light Water Reactor Sustainability Program and the EPRI Long Term Operations Program. The manuscript is co-authored by UT-Battelle, LLC under Contract 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, 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 ). The authors would like to thank Mr. Scott White, Clay Morris, Travis Dixon for their assistance. This research was sponsored by the U.S. Department of Energy (DOE), Office of Nuclear Energy - Light Water Reactor Sustainability Program and the EPRI Long Term Operations Program. The manuscript is co-authored by UT-Battelle, LLC under Contract 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, 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). The authors would like to thank Mr. Scott White, Clay Morris, Travis Dixon for their assistance.

Funders	Funder number
DOE Public Access Plan
Office of Nuclear Energy - Light Water Reactor Sustainability Program
United States Government
U.S. Department of Energy
Electric Power Research Institute	DE-AC05–00OR22725

Keywords

Helium induced crack
Irradiated materials
Laser repair welding

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10.1016/j.jnucmat.2021.153206

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title = "Suppression of Helium Induced Cracking in Laser Repair Welding of Highly Irradiated Stainless Steels",

abstract = "Welding repair of irradiated nuclear reactor materials such as austenitic stainless steels used for the reactor internals has been challenging due to irradiation generated helium in the material matrix over an extended period of time. In this study, improved laser welding techniques, including the novel Auxiliary Beam Stress Improved (ABSI) technique that proactively manages the stresses during laser repair welding is investigated to substantially reduce or avoid the occurrence of intergranular helium-induced cracking (HeIC). Laser weld cladding, with and without ABSI technique, was applied to deposit weld metal on irradiated stainless steel (Type 304 L) blocks with various helium concentrations up to approximately 20 atomic parts per million (appm). Welded samples were cross-sectioned and analyzed using optical and electron microscopes. It was found that, with the improved laser welding techniques, no macroscopic (millimeter-sized) cracks were observed in any of the samples. Microscopic (less than 50 μm) cracks were present in the heat affected zone. Statistical analysis on the sample with the highest helium concentration (~20 appm) reveals that the ABSI technique could effectively reduce the size and amounts of microscopic cracks.",

keywords = "Helium induced crack, Irradiated materials, Laser repair welding",

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doi = "10.1016/j.jnucmat.2021.153206",

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AU - Miller, Roger

AU - Curlin, Stephanie

AU - Dai, Tao

AU - Mao, Keyou

AU - Sutton, Benjamin

AU - Frederick, Greg

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N2 - Welding repair of irradiated nuclear reactor materials such as austenitic stainless steels used for the reactor internals has been challenging due to irradiation generated helium in the material matrix over an extended period of time. In this study, improved laser welding techniques, including the novel Auxiliary Beam Stress Improved (ABSI) technique that proactively manages the stresses during laser repair welding is investigated to substantially reduce or avoid the occurrence of intergranular helium-induced cracking (HeIC). Laser weld cladding, with and without ABSI technique, was applied to deposit weld metal on irradiated stainless steel (Type 304 L) blocks with various helium concentrations up to approximately 20 atomic parts per million (appm). Welded samples were cross-sectioned and analyzed using optical and electron microscopes. It was found that, with the improved laser welding techniques, no macroscopic (millimeter-sized) cracks were observed in any of the samples. Microscopic (less than 50 μm) cracks were present in the heat affected zone. Statistical analysis on the sample with the highest helium concentration (~20 appm) reveals that the ABSI technique could effectively reduce the size and amounts of microscopic cracks.

AB - Welding repair of irradiated nuclear reactor materials such as austenitic stainless steels used for the reactor internals has been challenging due to irradiation generated helium in the material matrix over an extended period of time. In this study, improved laser welding techniques, including the novel Auxiliary Beam Stress Improved (ABSI) technique that proactively manages the stresses during laser repair welding is investigated to substantially reduce or avoid the occurrence of intergranular helium-induced cracking (HeIC). Laser weld cladding, with and without ABSI technique, was applied to deposit weld metal on irradiated stainless steel (Type 304 L) blocks with various helium concentrations up to approximately 20 atomic parts per million (appm). Welded samples were cross-sectioned and analyzed using optical and electron microscopes. It was found that, with the improved laser welding techniques, no macroscopic (millimeter-sized) cracks were observed in any of the samples. Microscopic (less than 50 μm) cracks were present in the heat affected zone. Statistical analysis on the sample with the highest helium concentration (~20 appm) reveals that the ABSI technique could effectively reduce the size and amounts of microscopic cracks.

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Suppression of Helium Induced Cracking in Laser Repair Welding of Highly Irradiated Stainless Steels

Abstract

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Keywords

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