Effects of Heat Treatment on Microstructure and Mechanical Properties of a Bimodal Grain Ultra-Low Carbon 9Cr-ODS Steel

doi:10.11900/0412.1961.2020.00507

IMR OpenIR

	Effects of Heat Treatment on Microstructure and Mechanical Properties of a Bimodal Grain Ultra-Low Carbon 9Cr-ODS Steel
	Zhang Jiarong 1,2; Li Yanfen 2,3; Wang Guangquan 2,4; Bao Feiyang 2,4; Rui Xiang 2,4; Shi Quanqiang 2,3; Yan Wei 2,3; Shan Yiyin 2,3; Yang Ke 2
通讯作者	Li Yanfen(yfli@imr.ac.cn) ; Shan Yiyin(yyshan@imr.ac.cn)
	2022-05-01
发表期刊	ACTA METALLURGICA SINICA
ISSN	0412-1961
卷号	58 期号:5 页码:623-636
摘要	Oxide dispersion strengthened (ODS) steel is a promising structural material for advanced nuclear power systems. In this study, an ultra-low carbon 9Cr-ODS steel with a bimodal grain structure was prepared using powder metallurgy, and a superior matching of strength and plasticity was expected by adjusting the soft-hard matching of the coarse-grained and fine-grained regions. The effects of heat treatment on microstructure and mechanical properties of the ultra-low carbon 9Cr-ODS steel were evaluated through OM, SEM, TEM, microhardness, and tensile tests. The results demonstrated that the ultra-low carbon 9Cr-ODS steel exhibited a tempered martensite structure after normalizing at 1050-1200 degrees C, and then tempering at 700 and 750 degrees C. Moreover, it presented the microstructure characteristics of coarse-grained and fine-grained regions, in which the average grain size of fine-grained regions was 1.6 mu m and that of coarse-grained regions was 4.3 mu m. The dislocation density in the ultra-low carbon 9Cr-ODS steel was very high and the number density of nano-scale oxide particles was up to about 10(22) m(3). The microhardness in fine-grained regions was higher than that in coarse-grained regions. As the normalizing temperature increased, the microhardness of the ultra-low carbon 9Cr-ODS steel first increased and then decreased. The microhardness reached the highest after normalizing at 1100 degrees C. When the normalizing temperature increased to 1200 degrees C, the microhardness decreased due to the growth of austenitic grains. Regarding the tempering temperature, the microhardness first decreased and then increased as the tempering temperature increased from 700 degrees C to 800 degrees C. Furthermore, the decrease in microhardness when tempering at 700 and 750 degrees C was because the microstructure was recovered and softened. The higher the tempering temperature, the lower the microhardness. However, when tempering at 800 degrees C, the microhardness increased significantly, mainly due to the partial austenite transformation of martensite. The tensile test results at 25 degrees C showed that the strength of the ultra-low carbon 9Cr-ODS steel first decreased and then increased by increasing the tempering temperature, which was consistent with the microhardness change while the opposite was observed for elongation. The tensile test results at 700 degrees C showed that the strength of the ultra-low carbon 9Cr-ODS steel slightly decreased by increasing the tempering temperature. Moreover, the fracture morphology was dominated by fine dimples and secondary tearing, indicating that the ultra-low carbon 9Cr-ODS steel underwent ductile fracture. Combined with the mechanical property and fracture analysis results, the ultra-low carbon 9Cr-ODS steel exhibited superior matching of strength and plasticity after normalizing at 1150 degrees C for 1 h and tempering at 750 degrees C for 1 h.
关键词	ODS steel heat treatment bimodal grain microstructure mechanical property
资助者	National Natural Science Foundation of China ; Excellent Scholar Funding of Institute of Metal Research, Chinese Academy of Sciences
DOI	10.11900/0412.1961.2020.00507
收录类别	SCI
语种	英语
资助项目	National Natural Science Foundation of China[51971217] ; Excellent Scholar Funding of Institute of Metal Research, Chinese Academy of Sciences
WOS研究方向	Metallurgy & Metallurgical Engineering
WOS类目	Metallurgy & Metallurgical Engineering
WOS记录号	WOS:000787207700004
出版者	SCIENCE PRESS
引用统计	被引频次：4[WOS] [WOS记录] [WOS相关记录]
文献类型	期刊论文
条目标识符	http://ir.imr.ac.cn/handle/321006/172558
专题	中国科学院金属研究所
通讯作者	Li Yanfen; Shan Yiyin
作者单位	1.Northeastern Univ, Sch Mat Sci & Engn, Shenyang 110819, Peoples R China 2.Chinese Acad Sci, Shi Changxu Innovat Ctr Adv Mat, Inst Met Res, Shenyang 110016, Peoples R China 3.Chinese Acad Sci, Inst Met Res, CAS Key Lab Nucl Mat & Safety Assessment, Shenyang 110016, Peoples R China 4.Univ Sci & Technol China, Sch Mat Sci & Engn, Shenyang 110016, Peoples R China
推荐引用方式 GB/T 7714	Zhang Jiarong,Li Yanfen,Wang Guangquan,et al. Effects of Heat Treatment on Microstructure and Mechanical Properties of a Bimodal Grain Ultra-Low Carbon 9Cr-ODS Steel[J]. ACTA METALLURGICA SINICA,2022,58(5):623-636.
APA	Zhang Jiarong.,Li Yanfen.,Wang Guangquan.,Bao Feiyang.,Rui Xiang.,...&Yang Ke.(2022).Effects of Heat Treatment on Microstructure and Mechanical Properties of a Bimodal Grain Ultra-Low Carbon 9Cr-ODS Steel.ACTA METALLURGICA SINICA,58(5),623-636.
MLA	Zhang Jiarong,et al."Effects of Heat Treatment on Microstructure and Mechanical Properties of a Bimodal Grain Ultra-Low Carbon 9Cr-ODS Steel".ACTA METALLURGICA SINICA 58.5(2022):623-636.