Microstructural modelling and characterisation of laser-keyhole welded Eurofer 97

J. Hargreaves; S. Moore; G. Yuan; D. Liu; H. Tipping; R. Abbott; J. Tufnail; H. Dawson; T.l. Martin

doi:10.1016/j.matdes.2023.111614

Microstructural modelling and characterisation of laser-keyhole welded Eurofer 97

J. Hargreaves^*, S. Moore, G. Yuan, D. Liu, H. Tipping, R. Abbott, J. Tufnail, H. Dawson, T.l. Martin

^*Corresponding author for this work

Research output: Contribution to journal › Article (Academic Journal) › peer-review

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Abstract

The novel reduced activation ferritic/martensitic steel Eurofer 97 is employed by many concept designs for the plasma-facing first wall of the EU DEMO fusion reactor. These designs feature precision joints between Eurofer 97 coolant piping, for which an advanced laser-keyhole welding technique is proposed. In this work the microstructure of these novel laser-keyhole Eurofer 97 welds is modelled by combining finite element thermal analysis with precipitate kinetics modelling. Microanalysis of a representative specimen via scanning electron and high-speed atomic force microscopy techniques is also conducted, complimented by electron backscatter diffraction, energy-dispersive X-ray spectroscopy, and nanoindentation hardness testing. Models of the weld microstructure agree well with the results of microanalysis although the precipitate diameters predicted are slightly underestimated. Several large void defects were discovered within the weld fusion zone, the cause of which is suspected to arise from the evaporation of cerium-rich oxide inclusions present in the as-cast Eurofer 97 during welding.

Original language	English
Article number	111614
Journal	Materials and Design
Volume	226
Early online date	10 Jan 2023
DOIs	https://doi.org/10.1016/j.matdes.2023.111614
Publication status	Published - 1 Feb 2023

Bibliographical note

Funding Information:
The authors would like to thank UKAEA for providing a representative specimen of laser-welded Eurofer 97. This work was supported by the UK EPSRC via Nuclear Energy Futures CDT (EPSRC grant EP/S023844/1) and the University of Bristol. Dr Chris Jones is thanked for their assistance.

Publisher Copyright:
© 2023 The Authors

Keywords

fusion
nuclear
materials
steels

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title = "Microstructural modelling and characterisation of laser-keyhole welded Eurofer 97",

abstract = "The novel reduced activation ferritic/martensitic steel Eurofer 97 is employed by many concept designs for the plasma-facing first wall of the EU DEMO fusion reactor. These designs feature precision joints between Eurofer 97 coolant piping, for which an advanced laser-keyhole welding technique is proposed. In this work the microstructure of these novel laser-keyhole Eurofer 97 welds is modelled by combining finite element thermal analysis with precipitate kinetics modelling. Microanalysis of a representative specimen via scanning electron and high-speed atomic force microscopy techniques is also conducted, complimented by electron backscatter diffraction, energy-dispersive X-ray spectroscopy, and nanoindentation hardness testing. Models of the weld microstructure agree well with the results of microanalysis although the precipitate diameters predicted are slightly underestimated. Several large void defects were discovered within the weld fusion zone, the cause of which is suspected to arise from the evaporation of cerium-rich oxide inclusions present in the as-cast Eurofer 97 during welding.",

keywords = "fusion, nuclear, materials, steels",

author = "J. Hargreaves and S. Moore and G. Yuan and D. Liu and H. Tipping and R. Abbott and J. Tufnail and H. Dawson and T.l. Martin",

note = "Funding Information: The authors would like to thank UKAEA for providing a representative specimen of laser-welded Eurofer 97. This work was supported by the UK EPSRC via Nuclear Energy Futures CDT (EPSRC grant EP/S023844/1) and the University of Bristol. Dr Chris Jones is thanked for their assistance. Publisher Copyright: {\textcopyright} 2023 The Authors",

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T1 - Microstructural modelling and characterisation of laser-keyhole welded Eurofer 97

AU - Hargreaves, J.

AU - Moore, S.

AU - Yuan, G.

AU - Liu, D.

AU - Tipping, H.

AU - Abbott, R.

AU - Tufnail, J.

AU - Dawson, H.

AU - Martin, T.l.

N1 - Funding Information: The authors would like to thank UKAEA for providing a representative specimen of laser-welded Eurofer 97. This work was supported by the UK EPSRC via Nuclear Energy Futures CDT (EPSRC grant EP/S023844/1) and the University of Bristol. Dr Chris Jones is thanked for their assistance. Publisher Copyright: © 2023 The Authors

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N2 - The novel reduced activation ferritic/martensitic steel Eurofer 97 is employed by many concept designs for the plasma-facing first wall of the EU DEMO fusion reactor. These designs feature precision joints between Eurofer 97 coolant piping, for which an advanced laser-keyhole welding technique is proposed. In this work the microstructure of these novel laser-keyhole Eurofer 97 welds is modelled by combining finite element thermal analysis with precipitate kinetics modelling. Microanalysis of a representative specimen via scanning electron and high-speed atomic force microscopy techniques is also conducted, complimented by electron backscatter diffraction, energy-dispersive X-ray spectroscopy, and nanoindentation hardness testing. Models of the weld microstructure agree well with the results of microanalysis although the precipitate diameters predicted are slightly underestimated. Several large void defects were discovered within the weld fusion zone, the cause of which is suspected to arise from the evaporation of cerium-rich oxide inclusions present in the as-cast Eurofer 97 during welding.

AB - The novel reduced activation ferritic/martensitic steel Eurofer 97 is employed by many concept designs for the plasma-facing first wall of the EU DEMO fusion reactor. These designs feature precision joints between Eurofer 97 coolant piping, for which an advanced laser-keyhole welding technique is proposed. In this work the microstructure of these novel laser-keyhole Eurofer 97 welds is modelled by combining finite element thermal analysis with precipitate kinetics modelling. Microanalysis of a representative specimen via scanning electron and high-speed atomic force microscopy techniques is also conducted, complimented by electron backscatter diffraction, energy-dispersive X-ray spectroscopy, and nanoindentation hardness testing. Models of the weld microstructure agree well with the results of microanalysis although the precipitate diameters predicted are slightly underestimated. Several large void defects were discovered within the weld fusion zone, the cause of which is suspected to arise from the evaporation of cerium-rich oxide inclusions present in the as-cast Eurofer 97 during welding.

KW - fusion

KW - nuclear

KW - materials

KW - steels

U2 - 10.1016/j.matdes.2023.111614

DO - 10.1016/j.matdes.2023.111614

M3 - Article (Academic Journal)

SN - 0261-3069

VL - 226

JO - Materials and Design

JF - Materials and Design

M1 - 111614

ER -

Microstructural modelling and characterisation of laser-keyhole welded Eurofer 97

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