Influence of fatigue precracking and specimen size on Master Curve fracture toughness measurements of EUROFER97 and F82H steels

Xiang (Frank) Chen; Marta Serrano; Rebeca Hernández; Dan Lu; Mikhail A. Sokolov; Sehila M. Gonzalez De Vicente; Yutai Katoh

doi:10.1016/j.nme.2023.101393

Influence of fatigue precracking and specimen size on Master Curve fracture toughness measurements of EUROFER97 and F82H steels

Xiang (Frank) Chen, Marta Serrano, Rebeca Hernández, Dan Lu, Mikhail A. Sokolov, Sehila M. Gonzalez De Vicente, Yutai Katoh

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

1 Scopus citations

Abstract

EUROFER97 and F82H steels are two leading reduced-activation ferritic-martensitic (RAFM) steels for fusion first wall and blanket applications. Exposure to the harsh environment of fusion reactors can result in severe degradation of fracture toughness. Thus, the post-irradiation evaluation of fracture toughness is critical for understanding the material behavior. Due to the space constraints of irradiation facilities and challenges in controlling a uniform irradiation condition for large size specimens, the development of small specimen test techniques (SSTT) is indispensable to evaluate the performance of irradiated materials. In this study, we evaluated specimen size effects on the Master Curve fracture toughness of EUROFER97 and F82H steels. A wide variety of specimens, including 0.5 T compact tension (C(T)) specimens, 0.16 T mini-compact tension (miniC(T)) specimens, and 1.65 mm miniature bend bar specimens, were tested. The testing methodology was based on the Master Curve method in the ASTM E1921 standard. No specimen size effect was observed in 0.5 T C(T) and 0.16 T miniC(T) specimens on the Master Curve reference temperature T₀, while 1.65 mm miniature bend bar specimens yielded a higher T_0Q. A strong effect of fatigue precracking on T₀ for 0.5 T C(T) and 0.16 T miniC(T) specimens was observed, such that testing on specimens with skewed fatigue precrack fronts resulted in lower T₀ than for specimens with ASTM standard qualified straight fatigue precrack fronts. The results highlight the importance of experimental quality control in developing SSTT for Master Curve fracture toughness testing. Lastly, we also evaluated and provided recommendations on the minimum number of specimens needed for each specimen type for yielding reliable T_0Q values.

Original language	English
Article number	101393
Journal	Nuclear Materials and Energy
Volume	34
DOIs	https://doi.org/10.1016/j.nme.2023.101393
State	Published - Mar 2023

Funding

This research at ORNL was sponsored by the U.S. Department of Energy, Office of Fusion Energy Sciences, under contract DE-AC05-00OR22725 with UT-Battelle, LLC. The research at CIEMAT was sponsored by EUROFusion Consortium agreement and the Euratom research and training program under grant No 633053. We also appreciate the support from the IAEA CRP F13017 “Towards the Standardization of Small Specimen Test Techniques for Fusion Applications”. The views and opinions expressed herein do not necessarily reflect those of the International Atomic Energy Agency. The raw materials used in this study, EUROFER97 Batch-3 and F82H-BA12, were provided by Fusion for Energy (F4E) and National Institutes for Quantum Science and Technology (QST), respectively. This research at ORNL was sponsored by the U.S. Department of Energy, Office of Fusion Energy Sciences, under contract DE-AC05-00OR22725 with UT-Battelle, LLC. The research at CIEMAT was sponsored by EUROFusion Consortium agreement and the Euratom research and training program under grant No 633053. We also appreciate the support from the IAEA CRP F13017 “Towards the Standardization of Small Specimen Test Techniques for Fusion Applications”. The views and opinions expressed herein do not necessarily reflect those of the International Atomic Energy Agency. The raw materials used in this study, EUROFER97 Batch-3 and F82H-BA12, were provided by Fusion for Energy (F4E) and National Institutes for Quantum Science and Technology (QST), respectively. We appreciate contributions from the following personnel at ORNL: Eric Manneschmidt and Jordan Reed for performing fracture toughness testing; Doug Stringfield for facilitating specimen machining. Lastly, we would like to thank Tim Graening and TS Byun, also from ORNL, for their thoughtful review of this manuscript. Notice: This manuscript has been authored by UT-Battelle, LLC, under contract DE-AC05-00OR22725 with the US Department of Energy (DOE). The US government retains and the publisher, by accepting the article for publication, acknowledges that the US government retains a nonexclusive, paid-up, irrevocable, worldwide license to publish or reproduce the published form of this manuscript, or allow others to do so, for US government purposes. DOE will provide public access to these results of federally sponsored research in accordance with the DOE Public Access Plan (https://energy.gov/downloads/doe-public-access-plan).

Keywords

Fracture toughness
Fusion
Master curve
Reduced activation ferritic-martensitic steel
Small specimen test techniques
Specimen size effects

UN SDGs

This output contributes to the following UN Sustainable Development Goals (SDGs)

Access to Document

10.1016/j.nme.2023.101393

Cite this

@article{cd6795abfb014965a01660f058ffbd66,

title = "Influence of fatigue precracking and specimen size on Master Curve fracture toughness measurements of EUROFER97 and F82H steels",

abstract = "EUROFER97 and F82H steels are two leading reduced-activation ferritic-martensitic (RAFM) steels for fusion first wall and blanket applications. Exposure to the harsh environment of fusion reactors can result in severe degradation of fracture toughness. Thus, the post-irradiation evaluation of fracture toughness is critical for understanding the material behavior. Due to the space constraints of irradiation facilities and challenges in controlling a uniform irradiation condition for large size specimens, the development of small specimen test techniques (SSTT) is indispensable to evaluate the performance of irradiated materials. In this study, we evaluated specimen size effects on the Master Curve fracture toughness of EUROFER97 and F82H steels. A wide variety of specimens, including 0.5 T compact tension (C(T)) specimens, 0.16 T mini-compact tension (miniC(T)) specimens, and 1.65 mm miniature bend bar specimens, were tested. The testing methodology was based on the Master Curve method in the ASTM E1921 standard. No specimen size effect was observed in 0.5 T C(T) and 0.16 T miniC(T) specimens on the Master Curve reference temperature T0, while 1.65 mm miniature bend bar specimens yielded a higher T0Q. A strong effect of fatigue precracking on T0 for 0.5 T C(T) and 0.16 T miniC(T) specimens was observed, such that testing on specimens with skewed fatigue precrack fronts resulted in lower T0 than for specimens with ASTM standard qualified straight fatigue precrack fronts. The results highlight the importance of experimental quality control in developing SSTT for Master Curve fracture toughness testing. Lastly, we also evaluated and provided recommendations on the minimum number of specimens needed for each specimen type for yielding reliable T0Q values.",

keywords = "Fracture toughness, Fusion, Master curve, Reduced activation ferritic-martensitic steel, Small specimen test techniques, Specimen size effects",

author = "Chen, {Xiang (Frank)} and Marta Serrano and Rebeca Hern{\'a}ndez and Dan Lu and Sokolov, {Mikhail A.} and {Gonzalez De Vicente}, {Sehila M.} and Yutai Katoh",

note = "Publisher Copyright: {\textcopyright} 2023 The Author(s)",

year = "2023",

month = mar,

doi = "10.1016/j.nme.2023.101393",

language = "English",

volume = "34",

journal = "Nuclear Materials and Energy",

issn = "2352-1791",

publisher = "Elsevier",

}

TY - JOUR

T1 - Influence of fatigue precracking and specimen size on Master Curve fracture toughness measurements of EUROFER97 and F82H steels

AU - Chen, Xiang (Frank)

AU - Serrano, Marta

AU - Hernández, Rebeca

AU - Lu, Dan

AU - Sokolov, Mikhail A.

AU - Gonzalez De Vicente, Sehila M.

AU - Katoh, Yutai

PY - 2023/3

Y1 - 2023/3

N2 - EUROFER97 and F82H steels are two leading reduced-activation ferritic-martensitic (RAFM) steels for fusion first wall and blanket applications. Exposure to the harsh environment of fusion reactors can result in severe degradation of fracture toughness. Thus, the post-irradiation evaluation of fracture toughness is critical for understanding the material behavior. Due to the space constraints of irradiation facilities and challenges in controlling a uniform irradiation condition for large size specimens, the development of small specimen test techniques (SSTT) is indispensable to evaluate the performance of irradiated materials. In this study, we evaluated specimen size effects on the Master Curve fracture toughness of EUROFER97 and F82H steels. A wide variety of specimens, including 0.5 T compact tension (C(T)) specimens, 0.16 T mini-compact tension (miniC(T)) specimens, and 1.65 mm miniature bend bar specimens, were tested. The testing methodology was based on the Master Curve method in the ASTM E1921 standard. No specimen size effect was observed in 0.5 T C(T) and 0.16 T miniC(T) specimens on the Master Curve reference temperature T0, while 1.65 mm miniature bend bar specimens yielded a higher T0Q. A strong effect of fatigue precracking on T0 for 0.5 T C(T) and 0.16 T miniC(T) specimens was observed, such that testing on specimens with skewed fatigue precrack fronts resulted in lower T0 than for specimens with ASTM standard qualified straight fatigue precrack fronts. The results highlight the importance of experimental quality control in developing SSTT for Master Curve fracture toughness testing. Lastly, we also evaluated and provided recommendations on the minimum number of specimens needed for each specimen type for yielding reliable T0Q values.

AB - EUROFER97 and F82H steels are two leading reduced-activation ferritic-martensitic (RAFM) steels for fusion first wall and blanket applications. Exposure to the harsh environment of fusion reactors can result in severe degradation of fracture toughness. Thus, the post-irradiation evaluation of fracture toughness is critical for understanding the material behavior. Due to the space constraints of irradiation facilities and challenges in controlling a uniform irradiation condition for large size specimens, the development of small specimen test techniques (SSTT) is indispensable to evaluate the performance of irradiated materials. In this study, we evaluated specimen size effects on the Master Curve fracture toughness of EUROFER97 and F82H steels. A wide variety of specimens, including 0.5 T compact tension (C(T)) specimens, 0.16 T mini-compact tension (miniC(T)) specimens, and 1.65 mm miniature bend bar specimens, were tested. The testing methodology was based on the Master Curve method in the ASTM E1921 standard. No specimen size effect was observed in 0.5 T C(T) and 0.16 T miniC(T) specimens on the Master Curve reference temperature T0, while 1.65 mm miniature bend bar specimens yielded a higher T0Q. A strong effect of fatigue precracking on T0 for 0.5 T C(T) and 0.16 T miniC(T) specimens was observed, such that testing on specimens with skewed fatigue precrack fronts resulted in lower T0 than for specimens with ASTM standard qualified straight fatigue precrack fronts. The results highlight the importance of experimental quality control in developing SSTT for Master Curve fracture toughness testing. Lastly, we also evaluated and provided recommendations on the minimum number of specimens needed for each specimen type for yielding reliable T0Q values.

KW - Fracture toughness

KW - Fusion

KW - Master curve

KW - Reduced activation ferritic-martensitic steel

KW - Small specimen test techniques

KW - Specimen size effects

UR - http://www.scopus.com/inward/record.url?scp=85149060488&partnerID=8YFLogxK

U2 - 10.1016/j.nme.2023.101393

DO - 10.1016/j.nme.2023.101393

M3 - Article

AN - SCOPUS:85149060488

SN - 2352-1791

VL - 34

JO - Nuclear Materials and Energy

JF - Nuclear Materials and Energy

M1 - 101393

ER -

Influence of fatigue precracking and specimen size on Master Curve fracture toughness measurements of EUROFER97 and F82H steels

Abstract

Funding

Keywords

UN SDGs

Access to Document

Other files and links

Fingerprint

Cite this