Clarification of creep deformation mechanism in heat-affected zone of 9Cr steels with In Situ experiments

Yiyu Wang; Wei Zhang; Hui Huang; Yanli Wang; Weicheng Zhong; Jian Chen; Zhili Feng

doi:10.1016/j.scriptamat.2020.113640

Clarification of creep deformation mechanism in heat-affected zone of 9Cr steels with In Situ experiments

Yiyu Wang, Wei Zhang, Hui Huang, Yanli Wang, Weicheng Zhong, Jian Chen, Zhili Feng

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

18 Scopus citations

Abstract

This work quantified nonuniform creep deformation across the heterogeneous heat-affected zone (HAZ) of Grade 91 steel with sophisticated experiments, including an electric-thermal finite element model–assisted Gleeble thermomechanical simulation and a high-temperature creep testing with in situ digital image correlation (DIC). High temperature creep properties of HAZ sub-zones were quantitatively measured by the DIC. By utilizing peak temperature, hardness, local creep strain, and underlying microstructures, creep deformation mechanisms in HAZ were further understood. DIC measurements reveal a creep-vulnerable zone (CVZ) exposed to a peak temperature of 932°C (close to A_C₃) in the intercritical HAZ experienced the fastest creep strength degradation instead of the soft zone with the lowest hardness prior to creep. The significantly reduced precipitation strengthening from misplacement of undissolved and coarsened M₂₃C₆ carbides led to a faster recrystallization of tempered martensite in the CVZ. Weak untransformed tempered martensite (ferrite grains) stabilized by local Cr enrichment from dissolved M₂₃C₆ also harmed the CVZ's creep resistance.

Original language	English
Article number	113640
Journal	Scripta Materialia
Volume	194
DOIs	https://doi.org/10.1016/j.scriptamat.2020.113640
State	Published - Mar 15 2021

Funding

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 ( http://energy.gov/downloads/doe-public-access-plan ). This work is funded by a Department of Energy Office of Fossil Energy’s Crosscutting Research Program (FWP-FEAA118). The research and development work was performed at Oak Ridge National Laboratory, which is managed by UT-Battelle LLC for the US Department of Energy under contract DE-AC05- 00OR22725. The authors would like to thank Mr. Alan Frederick and Mr. Doug Kyle for their assistance in Gleeble and creep testing experiments.

Funders	Funder number
US Department of Energy
U.S. Department of Energy	DE-AC05- 00OR22725
Office of Fossil Energy	FWP-FEAA118
Oak Ridge National Laboratory
UT-Battelle

Keywords

Creep Failure
Creep Resistant Steel
Digital Image Correlation
Gleeble Simulation
Heat Affected Zone

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10.1016/j.scriptamat.2020.113640

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title = "Clarification of creep deformation mechanism in heat-affected zone of 9Cr steels with In Situ experiments",

abstract = "This work quantified nonuniform creep deformation across the heterogeneous heat-affected zone (HAZ) of Grade 91 steel with sophisticated experiments, including an electric-thermal finite element model–assisted Gleeble thermomechanical simulation and a high-temperature creep testing with in situ digital image correlation (DIC). High temperature creep properties of HAZ sub-zones were quantitatively measured by the DIC. By utilizing peak temperature, hardness, local creep strain, and underlying microstructures, creep deformation mechanisms in HAZ were further understood. DIC measurements reveal a creep-vulnerable zone (CVZ) exposed to a peak temperature of 932°C (close to AC3) in the intercritical HAZ experienced the fastest creep strength degradation instead of the soft zone with the lowest hardness prior to creep. The significantly reduced precipitation strengthening from misplacement of undissolved and coarsened M23C6 carbides led to a faster recrystallization of tempered martensite in the CVZ. Weak untransformed tempered martensite (ferrite grains) stabilized by local Cr enrichment from dissolved M23C6 also harmed the CVZ's creep resistance.",

keywords = "Creep Failure, Creep Resistant Steel, Digital Image Correlation, Gleeble Simulation, Heat Affected Zone",

author = "Yiyu Wang and Wei Zhang and Hui Huang and Yanli Wang and Weicheng Zhong and Jian Chen and Zhili Feng",

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doi = "10.1016/j.scriptamat.2020.113640",

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AU - Wang, Yiyu

AU - Zhang, Wei

AU - Huang, Hui

AU - Wang, Yanli

AU - Zhong, Weicheng

AU - Chen, Jian

AU - Feng, Zhili

PY - 2021/3/15

Y1 - 2021/3/15

N2 - This work quantified nonuniform creep deformation across the heterogeneous heat-affected zone (HAZ) of Grade 91 steel with sophisticated experiments, including an electric-thermal finite element model–assisted Gleeble thermomechanical simulation and a high-temperature creep testing with in situ digital image correlation (DIC). High temperature creep properties of HAZ sub-zones were quantitatively measured by the DIC. By utilizing peak temperature, hardness, local creep strain, and underlying microstructures, creep deformation mechanisms in HAZ were further understood. DIC measurements reveal a creep-vulnerable zone (CVZ) exposed to a peak temperature of 932°C (close to AC3) in the intercritical HAZ experienced the fastest creep strength degradation instead of the soft zone with the lowest hardness prior to creep. The significantly reduced precipitation strengthening from misplacement of undissolved and coarsened M23C6 carbides led to a faster recrystallization of tempered martensite in the CVZ. Weak untransformed tempered martensite (ferrite grains) stabilized by local Cr enrichment from dissolved M23C6 also harmed the CVZ's creep resistance.

AB - This work quantified nonuniform creep deformation across the heterogeneous heat-affected zone (HAZ) of Grade 91 steel with sophisticated experiments, including an electric-thermal finite element model–assisted Gleeble thermomechanical simulation and a high-temperature creep testing with in situ digital image correlation (DIC). High temperature creep properties of HAZ sub-zones were quantitatively measured by the DIC. By utilizing peak temperature, hardness, local creep strain, and underlying microstructures, creep deformation mechanisms in HAZ were further understood. DIC measurements reveal a creep-vulnerable zone (CVZ) exposed to a peak temperature of 932°C (close to AC3) in the intercritical HAZ experienced the fastest creep strength degradation instead of the soft zone with the lowest hardness prior to creep. The significantly reduced precipitation strengthening from misplacement of undissolved and coarsened M23C6 carbides led to a faster recrystallization of tempered martensite in the CVZ. Weak untransformed tempered martensite (ferrite grains) stabilized by local Cr enrichment from dissolved M23C6 also harmed the CVZ's creep resistance.

KW - Creep Failure

KW - Creep Resistant Steel

KW - Digital Image Correlation

KW - Gleeble Simulation

KW - Heat Affected Zone

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JO - Scripta Materialia

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ER -

Clarification of creep deformation mechanism in heat-affected zone of 9Cr steels with In Situ experiments

Abstract

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Keywords

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