Microstructure and mechanical properties of P91 steel steam pipe after long service

doi:10.13251/j.issn.0254-6051.2020.12.037

Abstract

Abstract: Microstructure of both the straight and the elbow section of P91 steel steam pipe served for 38000 h was studied by means of optical microscope (OM), scanning electron microscope (SEM) and transmission electron microscope (TEM), and corresponding mechanical properties were tested. The results show that the existence of a large amount of ferrite in the elbow microstructure is the main reason for sharp drop of its strength and hardness. It is concluded that the ferrite in the elbow is formed by the recrystallization of martensite during tempering due to the increase of energy caused by secondary deformation during bending.

Key words: P91 steel pipe, microstructure, mechanical properties, softening mechanism

CLC Number:

TG142.1

Qi Quanyou, Yang Xu. Microstructure and mechanical properties of P91 steel steam pipe after long service[J]. Heat Treatment of Metals, 2020, 45(12): 189-193.

References

[1] 李益民, 范长信, 杨百勋, 等. 大型火电机组用新型耐热钢[M]. 北京: 中国电力出版社, 2013.
[2] 束国刚, 刘江南, 石崇哲, 等. 超临界锅炉用T/P91钢的组织性能与工程应用[M]. 西安: 陕西科学技术出版社, 2006.
[3] Masuyama F, History of power plants and progress in heat resistant steels[J]. ISIJ International, 2001, 41(6): 612-625.
[4] 陆燕荪. 从超临界机组的发展透视研发新材料的紧迫性[J]. 发电设备, 2006(3): 149-151.
Lu Yansun.Urgency of R&D of new materials—Seen from the development of super-critical power generating units[J]. Power Equipment, 2006(3): 149-151.
[5] 高立新, 李炜丽, 侯小龙, 等. P91钢高温蒸汽管道低硬度对其理化性能的影响[J]. 华北电力技术, 2015(7): 37-43.
Gao Lixin, Li Weili, Hou Xiaolong, et al.Effects of low hardness on the physical properties of high temperature steam pipe of P91 steel[J]. North China Electric Power, 2015(7): 37-43.
[6] 杨超, 汤淳坡, 龚宏强, 等. 低硬度P91管件的安全性评价及寿命预测[J]. 中国电力, 2017, 50(8): 82-86.
Yang Chao, Yang Chunbo, Gong Hongqiang, et al.Safety evaluation and lifespan prediction of low hardness P91 pipes[J]. Electric Power, 2017, 50(8): 82-86.
[7] 王宝臣, 田旭海, 梁军, 等. P91钢管硬度低的原因分析及对性能的影响[J]. 神华科技, 2012, 10(3): 48-52.
Wang Baochen, Tian Xuhai, Liang Jun, et al.On the analysis of causes of low hardness of P91 steel tube and its influence on performance[J]. Shenhua Science and Technology, 2012, 10(3): 48-52.
[8] 钟万里, 李文胜, 王伟, 等. P91钢管长时间服役后的组织与力学性能[J]. 金属热处理, 2015, 40(6): 54-60.
Zhong Wanli, Li Wensheng, Wang Wei, et al.Microstructure and mechanical properties of P91 steel pipe after long term service[J]. Heat Treatment of Metals, 2015, 40(6): 54-60.
[9] 范德良, 王志武, 句光宇. P91钢管道异常低硬度部位的组织和性能[J]. 金属热处理, 2020, 45(3): 1-6.
Fan Deliang, Wang Zhiwu, Ju Guangyu.Microstructure and properties of P91 steel pipeline in abnormal low hardness parts[J]. Heat Treatment of Metals, 2020, 45(3): 1-6.
[10] Yan Wei, Wang Wei, Shan Yiyin, et al.Microstructural stability of 9-12%Cr ferrite/martensite heat-resistant steels[J]. Frontiers of Materials Science, 2013, 7(1): 1-27.
[11] Wang Wei, Yan Wei, Sha Wei, et al.Microstructural evolution and mechanical properties of short-term thermally exposed 9/12Cr heat-resistant steels[J]. Metallurgical and Materials Transactions A, 2012, 43(11): 4113-4122.
[12] 张冰, 王国亮, 肖功业, 等. 长期时效P91钢的组织与性能[J]. 材料热处理学报, 2013, 34(4): 123-127. Zhang Bing, Wang Guoliang, Xiao Gongye, et al. Microstructure and properties of P91 steel after long-term aging[J]. Transactions of Materials and Heat Treatment, 2013, 34(4): 123-127.
[13] 黄金督, 梅建平, 晏井利, 等. T91钢时效过程中的组织老化和性能变化[J]. 金属热处理, 2016, 41(11): 45-49.
Huang Jindu, Mei Jianping, Yan Jingli, et al.Microstructure degradation and properties evolution of T91 steel during aging[J]. Heat Treatment of Metals, 2016, 41(11): 45-49.
[14] 肖东平, 高淼淼, 谢逍原, 等. P91钢经冷变形及去应力处理后的组织和硬度[J]. 金属热处理, 2019, 44(8): 32-37.
Xiao Dongping, Gao Miaomiao, Xie Xiaoyuan, et al.Microstructure and hardness of P91 steel after cold deformation plus stress relieving treatment[J]. Heat Treatment of Metals, 2019, 44(8): 32-37.
[15] 蔡文河, 赵卫东, 王智春, 等. P91钢蒸汽管道软化机理与热处理工艺控制[J]. 热力发电, 2013, 42(1): 23-25.
Cai Wenhe, Zhao Weidong, Wang Zhichun, et al.Softening mechanism and heat treatment process control of P91 steel used for steam pipe[J]. Thermal Power Generation, 2013, 42(1): 23-25.
[16] 张道刚, 刘宗茂, 毛磊, 等. T91钢老化后组织与性能研究[J]. 金属热处理, 2008, 33(6): 88-90.
Zhang Daogang, Liu Zongmao, Mao Lei, et al.Microstructure and properties of T91 steel after accelerated aging[J]. Heat Treatment of Metals, 2008, 33(6): 88-90.