Behavior of grain boundary precipitates of P91 steel during creep process

doi:10.13251/j.issn.0254-6051.2023.05.005

Abstract

Abstract: Microstructure evolution and change law of grain boundary precipitates of P91 steel during the 600 ℃ and 650 ℃ creep rupture tests were studied. The results show that during the creep process, martensite lath tends to disperse gradually with the increase of creep rupture time, and the number and size of grain boundary precipitates increase. The grain boundary precipitates are mainly M₂₃C₆ and Laves(Fe₂Mo) phases, the nucleating location of Laves phase is mainly at the interface of M₂₃C₆ phase on the grain boundary, because M₂₃C₆ phase on grain boundary has a higher content of Mo than that in the matrix, providing favorable conditions for the formation and coarsening of Laves phase. At the same time, the segregation of Si on grain boundary increases the self diffusion coefficient of the steel, promotes the formation of Laves phase, and also makes the coarsening rate of Laves phase higher than that of M₂₃C₆ phase. During the creep process, the hardness of the P91 steel decreases with the extension of creep rupture time, and the higher the test temperature, the more obvious the decrease of the hardness.

Key words: P91 steel, creep, Laves phase, grain boundary precipitates

CLC Number:

TG142.1

Gu Baolan, Liu Jiachen, Sun Haoyu, Liu Wang, Yu Haiyang. Behavior of grain boundary precipitates of P91 steel during creep process[J]. Heat Treatment of Metals, 2023, 48(5): 25-31.

References

[1]朱丽慧, 赵钦新, 顾海澄, 等. 10Cr9Mo1VNbN耐热钢强化机理研究[J]. 机械工程材料, 1999, 23(1): 6-8.
Zhu Lihui, Zhao Qinxin, Gu Haicheng, et al. Investigation on the strengthening mechanism of 10Cr9Mo1VNbN heat-resistant steel[J]. Materials for Mechanical Engineering, 1999, 23(1): 6-8.
[2]于在松, 周荣灿, 王弘喆, 等. 高温服役138 000 h后T91钢显微组织结构分析[J]. 热力发电, 2008, 37(12): 20-25.
Yu Zaisong, Zhou Rongcan, Wang Hongzhe, et al. Microstructure analysis of T91 steel after 130 000 h in service under high temperature[J]. Thermal Power Generation, 2008, 37(12): 20-25.
[3]王学, 张珣, 占良飞. T91钢组织退化行为及对高温持久强度的影响[J]. 中国电机工程学报, 2012, 32(26): 137-142.
Wang Xue, Zhang Xun, Zhan Liangfei, et al. Microstructure degradation behavior and its influence on high temperature stress rupture limit of T91 steel[J]. Proceedings of the CSEE, 2012, 32(26): 137-142.
[4]Kimura K, Kushima H, Abe F. Heterogeneous changes in microstructure and degradation behavior of 9Cr-1Mo-V-Nb steel during long term creep[C]// International Conference on Creep and Fracture of Engineering Materials and Structures. 2000, 171-174: 483-490.
[5]Wang Xue, Wang Xiao, Li Huijun, et al. Laves phase precipitation behavior in the simulated fine-grained heat-affected zone of creep strength enhanced ferritic steel P92 and its role in creep void nucleation and growth[J]. Weld World, 2017, 61: 231-239.
[6]Dimmler G, Weinert P, Kozeschnik E, et a1. Quantification of the Laves phase in advanced 9%-12%Cr steels using a standard SEM[J]. Materials Characterization, 2003, 51(5): 341-352.
[7]Cerjak H, Hofer P, Schaffernak B. Microstructural aspects on creep behaviour of advanced power plant steels[J]. Key Engineering Materials, 2000, 171-174: 453-460.
[8]Abe F. Coarsening behavior of lath and its effect on creep rates in tempered martensitic 9Cr-W steels[J]. Materials Science and Engineering A, 2004, 387/389: 565-569.
[9]王学, 于淑敏, 任遥遥. P92 钢时效的Laves相演化行为[J]. 金属学报, 2014, 50(10): 1195-1202.
Wang Xue, Yu Shumin, Ren Yaoyao. Laves phase evolution in P92 steel during ageing[J]. Acta Metallurgica Sinica, 2014, 50(10): 1195-1202.
[10]张红军, 刘树涛, 范长信. 国产P91钢在蠕变过程中微观组织和性能的变化[J]. 中国电力, 2007, 40(7): 12-16.
Zhang Hongjun, Liu Shutao, Fan Changxin. Variation in microstructure and performance during the creep of domestic P91 steel[J]. Electric Power, 2007, 40(7): 12-16.
[11]崔正强, 王延峰, 赵双群, 等. T91钢管在600 ℃长期时效后的组织及力学性能[J]. 机械工程材料, 2014, 38(12): 78-81.
Cui Zhengqiang, Wang Yanfeng, Zhao Shuangqun, et al. Microstructure and mechanical properties of T91 steel tube after long-term aging at 600 ℃[J]. Materials for Mechanical Engineering, 2014, 38(12): 78-81.
[12]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 pipe in abnormal low hardness parts[J]. Heat Treatment of Metals, 2020, 45(3): 1-6.
[13]Hald J, Korcakova L. Precipitate stability in creep resistant ferritic steels-Experimental investigations and modeling[J]. ISIJ International, 2003, 43: 420-427.
[14]Thomas V, Saroja S, Vijayalakshmi M. Microstructural stability of modified 9Cr-Mo steel during long term exposures at elevated temperatures[J]. Journal of Nuclear Materials, 2008, 378(3): 273-281.

[1]	Deng Shanshan, Sun Yongqing, Jiang Yehua, Liu Zhenbao, Liang Jianxiong, Wang Changjun. High temperature rupture properties of A286 alloy [J]. Heat Treatment of Metals, 2023, 48(3): 179-187.
[2]	Zhang Anwen, Wang Yang, Zhang Zhibo, Jiang Feng. Martensitic degeneration behavior of P91 steel served for eighty-eight thousand hours in a supercritical unit [J]. Heat Treatment of Metals, 2023, 48(2): 74-78.
[3]	Tian Ning, Zhao Guoqi, Zhang Ping, Xiang Xianli, Tian Sugui, Zhang Shunke, Yan Huajin. Effect of heat treatment on microstructure and creep behavior of directionally solidified alloy DZ125 [J]. Heat Treatment of Metals, 2022, 47(8): 188-193.
[4]	Zhong Xiuyang, Deng Tongsheng, Zhu Zhiyun, Li Shang, Zhong Ming, Guo Tao. Effect of aging on microstructure and properties of rare earth Sc microalloyed titanium alloy [J]. Heat Treatment of Metals, 2022, 47(7): 40-46.
[5]	Gao Dong, Qian Lingyi, Guo Yunshan, Huang Aihua. Influence of thermal barrier coatings on multiaxial thermo-mechanical fatigue properties of single crystal superalloy [J]. Heat Treatment of Metals, 2022, 47(6): 216-221.
[6]	Yuan Zhi, Zhang Hailian, Zhang Huijie, Ma Qingshuang, He Xiang, Bi Changbo, Li Huijun, Gao Qiuzhi. Research status of high-temperature creep properties of novel alumina-forming austenitic heat-resistant steel [J]. Heat Treatment of Metals, 2022, 47(5): 14-24.
[7]	Zhang Kai, Wang Xue, Ni Mansheng, Liu Junjian, Du Chengchao. Effect of high temperature aging on microstructure and hardness of P91 steel [J]. Heat Treatment of Metals, 2022, 47(12): 7-12.
[8]	Chen Rui, Bao Cuimin, Yang Zhipeng, Chen Wei, Wang Shengchi, Lin Lin. Medium and high temperature mechanical properties of martensitic stainless steel [J]. Heat Treatment of Metals, 2022, 47(11): 100-105.
[9]	Lu Yuhua, Wang Haizhou, Fu Rui, Li Fulin, Li Dongling, Huang Danqi, Cai Wenyi. Behavior of γ′ precipitates under high temperature creep of GH4096 superalloy with different solution treatment cooling rates [J]. Heat Treatment of Metals, 2021, 46(9): 173-179.
[10]	Wang Ni, Liu Xinbao, Zhu Lin, Li Bo, Quan Chen. Analysis of transient creep behavior of P91 steel [J]. Heat Treatment of Metals, 2021, 46(8): 20-25.
[11]	Quan Chen, Liu Xinbao, Zhu Lin, Li Bo, Wang Ni. Microstructure evolution behavior of high chromium heat-resistant steel during creep [J]. Heat Treatment of Metals, 2021, 46(6): 135-145.
[12]	Yang Jinping, Song Guobin, Dong Yongjun, Cui Chong, Duan Wenfeng, Shi Quanqiang, Shan Yiyin. Microstructure and properties of a gas turbine blade after long-term service [J]. Heat Treatment of Metals, 2021, 46(6): 213-220.
[13]	Yang Hao, Si Yu, Cao Pengjun, Li Kejian. Research status of failure mechanisms of heat-resistant steel in thermal power units [J]. Heat Treatment of Metals, 2021, 46(5): 14-24.
[14]	Deng Hui. Microstructure, properties and safety evaluation of low hardness P91 steel tube after long service [J]. Heat Treatment of Metals, 2021, 46(12): 209-213.
[15]	Zheng Jianjun, Fan Ziming, Liu Xiao, Qiao Xin, Gao Yunpeng. Failure analysis of fastening bolts of one steam turbine valve cover [J]. Heat Treatment of Metals, 2021, 46(10): 262-266.