High-temperature Creep Behavior of Oxide Dispersion Strengthened HT9 Steel at 650 ℃ Based on Small Sample Testing

One of the most popular materials for advanced nuclear energy systems is oxide dispersion strengthened (ODS) steel, which has been widely adopted as a candidate material for advanced nuclear energy systems due to its high-temperature mechanical properties and resistance to irradiation. Because of th...

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Main Author: CHENG Shuo1, LI Shijiang1, GONG Aoxiang1, ZHAO Lei2, TONG Zhenfeng1
Format: Article
Language:English
Published: Editorial Board of Atomic Energy Science and Technology 2025-02-01
Series:Yuanzineng kexue jishu
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author CHENG Shuo1, LI Shijiang1, GONG Aoxiang1, ZHAO Lei2, TONG Zhenfeng1,
author_facet CHENG Shuo1, LI Shijiang1, GONG Aoxiang1, ZHAO Lei2, TONG Zhenfeng1,
author_sort CHENG Shuo1, LI Shijiang1, GONG Aoxiang1, ZHAO Lei2, TONG Zhenfeng1,
collection DOAJ
description One of the most popular materials for advanced nuclear energy systems is oxide dispersion strengthened (ODS) steel, which has been widely adopted as a candidate material for advanced nuclear energy systems due to its high-temperature mechanical properties and resistance to irradiation. Because of the powder metallurgy preparation process used in the preparation of ODS steels, the material is mostly of fine or ultra-fine crystalline organization. The mechanism of high-temperature creep behavior of this type of such fine-crystalline materials is more complex, and there are few researches on the mechanistic changes in the creep deformation process. In addition, there is a lack of in-depth understanding of the effects on the creep behavior of grain scale and diffusely reinforced particles. In this paper, the oxide dispersion strengthened steel HT9-ODS and the reference HT9 steel were taken as the objects of study, and they were prepared into small-sized samples for high-temperature creep experiments. The experimental temperature was selected as the typical fast neutron reactor service temperature of 650 ℃, and the stress interval was 80-180 MPa. The creep fracture morphology and microstructure of the samples were characterized and tested by using micro-scale characterization techniques. By comparing and analyzing the high-temperature creep strain curves of reference HT9 steel and oxide dispersion strengthened steel HT9-ODS, the creep behavior of HT9-ODS steel at high temperatures was investigated. The results show that when the stress is higher than 100 MPa, grain boundary sliding plays a dominant role in the creep deformation process, which promotes crack initiation and aggregation, and fracture occurs in a shorter time for both HT9-ODS steel and the reference HT9 steel. The pinning of dislocations by oxide dispersed particles leads to the concentration of stress at grain boundaries, which accelerates the fracture of HT9-ODS steel, making the creep life of HT9-ODS steel shorter than that of reference HT9 steel. As the stress is reduced to 80 MPa, the grain boundary sliding effect decreases, and the creep deformation of reference HT9 and HT9-ODS steels is mainly the result of the synergistic effect of dislocation creep and diffusion creep. In this case, the dislocations of the reference HT9 steel cross the second phase particles in a climbing manner and the dislocations of the HT9-ODS steel bypass the second phase particles according to the Orowan mechanism. The creep life of HT9-ODS steel is much longer than that of reference HT9 steel due to the oxide dispersed particles hindering the dislocation motion.
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publisher Editorial Board of Atomic Energy Science and Technology
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spelling doaj-art-a89d93c2034a486bae69ac15b671769d2025-08-20T02:45:28ZengEditorial Board of Atomic Energy Science and TechnologyYuanzineng kexue jishu1000-69312025-02-0159243644310.7538/yzk.2024.youxian.0361High-temperature Creep Behavior of Oxide Dispersion Strengthened HT9 Steel at 650 ℃ Based on Small Sample TestingCHENG Shuo1, LI Shijiang1, GONG Aoxiang1, ZHAO Lei2, TONG Zhenfeng1, 01. School of Nuclear Science and Engineering, North China Electric Power University, Beijing 102206, China 2. State Grid Jibei Electric Power Co., Ltd. Super High Voltage Branch, Beijing 102400, ChinaOne of the most popular materials for advanced nuclear energy systems is oxide dispersion strengthened (ODS) steel, which has been widely adopted as a candidate material for advanced nuclear energy systems due to its high-temperature mechanical properties and resistance to irradiation. Because of the powder metallurgy preparation process used in the preparation of ODS steels, the material is mostly of fine or ultra-fine crystalline organization. The mechanism of high-temperature creep behavior of this type of such fine-crystalline materials is more complex, and there are few researches on the mechanistic changes in the creep deformation process. In addition, there is a lack of in-depth understanding of the effects on the creep behavior of grain scale and diffusely reinforced particles. In this paper, the oxide dispersion strengthened steel HT9-ODS and the reference HT9 steel were taken as the objects of study, and they were prepared into small-sized samples for high-temperature creep experiments. The experimental temperature was selected as the typical fast neutron reactor service temperature of 650 ℃, and the stress interval was 80-180 MPa. The creep fracture morphology and microstructure of the samples were characterized and tested by using micro-scale characterization techniques. By comparing and analyzing the high-temperature creep strain curves of reference HT9 steel and oxide dispersion strengthened steel HT9-ODS, the creep behavior of HT9-ODS steel at high temperatures was investigated. The results show that when the stress is higher than 100 MPa, grain boundary sliding plays a dominant role in the creep deformation process, which promotes crack initiation and aggregation, and fracture occurs in a shorter time for both HT9-ODS steel and the reference HT9 steel. The pinning of dislocations by oxide dispersed particles leads to the concentration of stress at grain boundaries, which accelerates the fracture of HT9-ODS steel, making the creep life of HT9-ODS steel shorter than that of reference HT9 steel. As the stress is reduced to 80 MPa, the grain boundary sliding effect decreases, and the creep deformation of reference HT9 and HT9-ODS steels is mainly the result of the synergistic effect of dislocation creep and diffusion creep. In this case, the dislocations of the reference HT9 steel cross the second phase particles in a climbing manner and the dislocations of the HT9-ODS steel bypass the second phase particles according to the Orowan mechanism. The creep life of HT9-ODS steel is much longer than that of reference HT9 steel due to the oxide dispersed particles hindering the dislocation motion.ht9 steelht9-ods steeloxide dispersion strengtheningcreep
spellingShingle CHENG Shuo1, LI Shijiang1, GONG Aoxiang1, ZHAO Lei2, TONG Zhenfeng1,
High-temperature Creep Behavior of Oxide Dispersion Strengthened HT9 Steel at 650 ℃ Based on Small Sample Testing
Yuanzineng kexue jishu
ht9 steel
ht9-ods steel
oxide dispersion strengthening
creep
title High-temperature Creep Behavior of Oxide Dispersion Strengthened HT9 Steel at 650 ℃ Based on Small Sample Testing
title_full High-temperature Creep Behavior of Oxide Dispersion Strengthened HT9 Steel at 650 ℃ Based on Small Sample Testing
title_fullStr High-temperature Creep Behavior of Oxide Dispersion Strengthened HT9 Steel at 650 ℃ Based on Small Sample Testing
title_full_unstemmed High-temperature Creep Behavior of Oxide Dispersion Strengthened HT9 Steel at 650 ℃ Based on Small Sample Testing
title_short High-temperature Creep Behavior of Oxide Dispersion Strengthened HT9 Steel at 650 ℃ Based on Small Sample Testing
title_sort high temperature creep behavior of oxide dispersion strengthened ht9 steel at 650 ℃ based on small sample testing
topic ht9 steel
ht9-ods steel
oxide dispersion strengthening
creep
work_keys_str_mv AT chengshuo1lishijiang1gongaoxiang1zhaolei2tongzhenfeng1 hightemperaturecreepbehaviorofoxidedispersionstrengthenedht9steelat650basedonsmallsampletesting