Microstructure, hardness and creep properties for P91 steel after long-term service in a ultra-supercritical power plant

IF 3 2区工程技术 Q2 ENGINEERING, MECHANICAL

International Journal of Pressure Vessels and Piping Pub Date : 2024-09-19 DOI:10.1016/j.ijpvp.2024.105330

Xiaoxiang Sun , Chang Che , Gong Qian , Xue Wang

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引用次数: 0

Abstract

3 P91 pipes enduring 5∼6 × 10⁴ h service had been found in an ultra-supercritical power plant. Hardness tests, microstructure observation(OM, SEM/EBSD, TEM/EDS) and creep rupture tests were performed, and the relationship between hardness, microstructure and creep rupture strength were discussed. Results showed that 1 of the 3 pipes still featured lath martensite, and its mechanical properties complied with relevant criteria. Other 2 pipes were characteristic of a mixture of ferrite and highly recovered martensite. Their hardness and creep rupture strength experienced severe degradation. Laves phase was observed in all 3 pipes. The most distinctive feature of the 2 low hardness pipes was their coarse and intragranularly distributed M₂₃C₆. This might be caused by abnormal heat treatments which could lead to the mixed microstructure of martensite and ferrite, and this kind of microstructure would degrade fast during service. Thus the low hardness had nothing to do with the precipitation of Laves phase.

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P91 钢在超超临界发电厂长期使用后的微观结构、硬度和蠕变特性

在一个超超临界发电厂中发现了 3 根 P91 管道，其使用寿命为 5 ∼ 6 × 104 h。对其进行了硬度测试、微观结构观察（OM、SEM/EBSD、TEM/EDS）和蠕变断裂测试，并讨论了硬度、微观结构和蠕变断裂强度之间的关系。结果表明，3 根钢管中的 1 根仍以板条马氏体为特征，其机械性能符合相关标准。另外两根钢管的特征是铁素体和高恢复马氏体的混合物。它们的硬度和蠕变断裂强度严重下降。在所有 3 根钢管中都观察到了拉维斯相。两根低硬度钢管的最显著特点是M23C6粗大且晶粒内分布。这可能是由于不正常的热处理导致了马氏体和铁素体的混合显微结构，而这种显微结构在使用过程中会快速退化。因此，低硬度与拉夫相的析出无关。

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来源期刊

International Journal of Pressure Vessels and Piping 工程技术-工程：机械

CiteScore

5.30

自引率

13.30%

发文量

208

审稿时长

17 months

期刊介绍： Pressure vessel engineering technology is of importance in many branches of industry. This journal publishes the latest research results and related information on all its associated aspects, with particular emphasis on the structural integrity assessment, maintenance and life extension of pressurised process engineering plants. The anticipated coverage of the International Journal of Pressure Vessels and Piping ranges from simple mass-produced pressure vessels to large custom-built vessels and tanks. Pressure vessels technology is a developing field, and contributions on the following topics will therefore be welcome: • Pressure vessel engineering • Structural integrity assessment • Design methods • Codes and standards • Fabrication and welding • Materials properties requirements • Inspection and quality management • Maintenance and life extension • Ageing and environmental effects • Life management Of particular importance are papers covering aspects of significant practical application which could lead to major improvements in economy, reliability and useful life. While most accepted papers represent the results of original applied research, critical reviews of topical interest by world-leading experts will also appear from time to time. International Journal of Pressure Vessels and Piping is indispensable reading for engineering professionals involved in the energy, petrochemicals, process plant, transport, aerospace and related industries; for manufacturers of pressure vessels and ancillary equipment; and for academics pursuing research in these areas.