{"title":"Evolution of carbides and Charpy toughness in a low alloy bainitic steel during step-up aging process","authors":"Long Jin, Kun Zhang, Ming-Liang Zhu, Fu-Zhen Xuan","doi":"10.1038/s41529-024-00527-w","DOIUrl":null,"url":null,"abstract":"The low alloy bainitic steel used in reactor pressure vessels deteriorates during thermal service while the macroscopic thermodynamic parameters that cause thermal aging remains unknown. In this work, a thermal aging restructuring scheme was proposed by step-up aging the steel from 350 °C to 490 °C, with a total duration of 7500 hours. Samples from varied thickness of the steel were characterized in terms of carbides evolution and Charpy impact toughness at 20 °C. The carbide size and its fraction were statistically analyzed showing partial coarsening and dissolution during aging, while the carbide fraction was found linearly correlated with the impact energy for the first time. The critical transition temperature parameter of the aging process was found to be 470 °C for the steel. The macroscopic thermodynamic parameters, including the thermal aging time and temperature, facilitate a comprehensive understanding of the material degradation mechanism and provide a basis for long-term safety of equipment.","PeriodicalId":19270,"journal":{"name":"npj Materials Degradation","volume":" ","pages":"1-11"},"PeriodicalIF":6.6000,"publicationDate":"2024-10-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.nature.com/articles/s41529-024-00527-w.pdf","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"npj Materials Degradation","FirstCategoryId":"88","ListUrlMain":"https://www.nature.com/articles/s41529-024-00527-w","RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q1","JCRName":"MATERIALS SCIENCE, MULTIDISCIPLINARY","Score":null,"Total":0}
引用次数: 0
Abstract
The low alloy bainitic steel used in reactor pressure vessels deteriorates during thermal service while the macroscopic thermodynamic parameters that cause thermal aging remains unknown. In this work, a thermal aging restructuring scheme was proposed by step-up aging the steel from 350 °C to 490 °C, with a total duration of 7500 hours. Samples from varied thickness of the steel were characterized in terms of carbides evolution and Charpy impact toughness at 20 °C. The carbide size and its fraction were statistically analyzed showing partial coarsening and dissolution during aging, while the carbide fraction was found linearly correlated with the impact energy for the first time. The critical transition temperature parameter of the aging process was found to be 470 °C for the steel. The macroscopic thermodynamic parameters, including the thermal aging time and temperature, facilitate a comprehensive understanding of the material degradation mechanism and provide a basis for long-term safety of equipment.
期刊介绍：
npj Materials Degradation considers basic and applied research that explores all aspects of the degradation of metallic and non-metallic materials. The journal broadly defines ‘materials degradation’ as a reduction in the ability of a material to perform its task in-service as a result of environmental exposure.
The journal covers a broad range of topics including but not limited to:
-Degradation of metals, glasses, minerals, polymers, ceramics, cements and composites in natural and engineered environments, as a result of various stimuli
-Computational and experimental studies of degradation mechanisms and kinetics
-Characterization of degradation by traditional and emerging techniques
-New approaches and technologies for enhancing resistance to degradation
-Inspection and monitoring techniques for materials in-service, such as sensing technologies
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