长时服役后P92钢的显微组织与力学性能

doi:10.13251/j.issn.0254-6051.2025.12.010

摘要/Abstract

摘要： 对经70 000 h长时服役的P92钢管道进行微观组织表征和力学性能测试,并与1060 ℃×2 h正火+770 ℃×2 h回火态P92钢进行对比,研究P92钢长时服役后的显微组织演变与力学性能变化。结果表明:长时服役后组织中马氏体发生回复,晶内位错密度下降,Laves相在晶界或板条界析出并长大、粗化,部分晶界或相界出现蠕变孔洞;相比于正火+回火态,长时服役后的P92钢硬度、强度和塑、韧性均下降,其中冲击吸收能量、高温抗拉强度、屈服强度及伸长率等指标低于相应标准要求的下限值;持久强度显著降低,较标准推荐的600 ℃持久强度平均值下降约13%。此外,结果表明,长时服役后的P92钢经过重新热处理后,可以部分恢复组织特征、硬度、冲击性能及室温拉伸性能;但无法完全恢复其高温性能,这与服役态P92钢中存在的蠕变损伤(孔洞)无法通过热处理消除有关。

关键词: P92钢, 长时服役, 显微组织, 力学性能

Abstract: Microstructure characterization and mechanical properties tests were conducted on P92 steel pipe after 70 000 h of long-term service. The results were compared with those of the P92 steel in the normalized (1060 ℃×2 h) and tempered (770 ℃×2 h) condition to investigate the microstructural evolution and mechanical property changes. The results indicate that after long-term service, the martensite undergoes recovery, the intragranular dislocation density decreases, Laves phases precipitate, grow and coarsen at grain boundaries or lath boundaries, and creep cavities form at some grain boundaries or phase boundaries. Compared to the normalizing+tempering state P92 steel, the hardness, strength, plasticity and toughness of the P92 steel after long-term service are decreased, in which the impact absorbed energy, high temperature tensile strength, high temperature yield strength, and elongation are lower than the minimum values of the corresponding standards requirement. The creep rupture strength is significantly reduced after long-term service, which reduced by 13% compared with the average creep rupture strength at 600 ℃ mentioned in standard. Nevertheless, the results show that the microstructure characteristics, hardness, impact property and room temperature tensile property of the P92 steel after long-term service can be restored by a proper re-heat treatment. However, its high-temperature property cannot be fully recovered, which is attributed to the presence of creep damage (voids) in the service state P92 steel that cannot be eliminated by heat treatment.

Key words: P92 steel, long-term service, microstructure, mechanical properties

中图分类号:

TG142.79

李勇, 王家庆, 方文, 王万里. 长时服役后P92钢的显微组织与力学性能[J]. 金属热处理, 2025, 50(12): 63-69.

Li Yong, Wang Jiaqing, Fang Wen, Wang Wanli. Microstructure and mechanical properties of P92 steel after long-term service[J]. Heat Treatment of Metals, 2025, 50(12): 63-69.

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