Microstructure evolution and mechanical properties in 718H pre-hardened mold steel during tempering

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	Microstructure evolution and mechanical properties in 718H pre-hardened mold steel during tempering
	Liu, HH; Fu, PX; Liu, HW; Sun, C; Ma, XP; Li, DZ; Fu, PX (reprint author), Chinese Acad Sci, Inst Met Res, Beijing, Peoples R China.
刊名	MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING
	2018-01-02
卷号	709 页码:181-192
关键词	Heat-resistant Steel Carbide Precipitation Cr-w Retained Austenite Temperature Alloy Strength Fatigue Toughness Behavior
ISSN号	0921-5093
英文摘要	The effects of tempering temperature on the microstructure and mechanical properties of 718H pre-hardened mold steel were investigated. After normalizing and quenching treatments, seven specimens were tempered at a temperature in the range of 500-650 degrees C for two hours. After heat treatments, the tempered microstructures were characterized by X-ray diffraction, scanning electron microscopy (SEM), and transmission electron microscopy. In addition, the phase identification and microchemistry of tempered carbides were performed by the physicochemical phase analysis method; then the precipitation sequence of tempered carbides was examined in detail by transmission electron microscopy and selected area electron diffraction patterns. Results indicate that the yield strength, ultimate tensile strength, and the hardness decrease; in contrast, impact energy increases with the increase in tempering temperature. The influence of tempering temperature on mechanical properties of 718H steel is attributed to the precipitation of tempered carbides, the recovery of the martensite lath, the dislocation density, and the grain structure. Furthermore, a more accurate study of the micromechanics was performed through the fatigue crack growth test. And a correlation between microstructure and mechanical properties was established by electron back-scattered diffraction. Finally, the fracture surface of the impact specimen was analyzed by SEM and energy-dispersive X-ray spectroscopy. According to the change in microstructure and mechanical properties as a function of tempering temperature, the optimal tempering temperature has been determined in the range of 530-560 degrees C.; The effects of tempering temperature on the microstructure and mechanical properties of 718H pre-hardened mold steel were investigated. After normalizing and quenching treatments, seven specimens were tempered at a temperature in the range of 500-650 degrees C for two hours. After heat treatments, the tempered microstructures were characterized by X-ray diffraction, scanning electron microscopy (SEM), and transmission electron microscopy. In addition, the phase identification and microchemistry of tempered carbides were performed by the physicochemical phase analysis method; then the precipitation sequence of tempered carbides was examined in detail by transmission electron microscopy and selected area electron diffraction patterns. Results indicate that the yield strength, ultimate tensile strength, and the hardness decrease; in contrast, impact energy increases with the increase in tempering temperature. The influence of tempering temperature on mechanical properties of 718H steel is attributed to the precipitation of tempered carbides, the recovery of the martensite lath, the dislocation density, and the grain structure. Furthermore, a more accurate study of the micromechanics was performed through the fatigue crack growth test. And a correlation between microstructure and mechanical properties was established by electron back-scattered diffraction. Finally, the fracture surface of the impact specimen was analyzed by SEM and energy-dispersive X-ray spectroscopy. According to the change in microstructure and mechanical properties as a function of tempering temperature, the optimal tempering temperature has been determined in the range of 530-560 degrees C.
学科主题	Nanoscience & Nanotechnology ; Materials Science, Multidisciplinary ; Metallurgy & Metallurgical Engineering
语种	英语
资助机构	National Key Research and Development Program of China [2016YFB0300401]; Cooperation Program of Hubei Province and Chinese Academy of Sciences (The Research and Development of Key Technologies for Special Steel of Homogeneous High Performance)
公开日期	2018-06-05
内容类型	期刊论文
源URL	[http://ir.imr.ac.cn/handle/321006/79593]
专题	金属研究所_中国科学院金属研究所
通讯作者	Fu, PX (reprint author), Chinese Acad Sci, Inst Met Res, Beijing, Peoples R China.
推荐引用方式 GB/T 7714	Liu, HH,Fu, PX,Liu, HW,et al. Microstructure evolution and mechanical properties in 718H pre-hardened mold steel during tempering[J]. MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING,2018,709:181-192.
APA	Liu, HH.,Fu, PX.,Liu, HW.,Sun, C.,Ma, XP.,...&Fu, PX .(2018).Microstructure evolution and mechanical properties in 718H pre-hardened mold steel during tempering.MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING,709,181-192.
MLA	Liu, HH,et al."Microstructure evolution and mechanical properties in 718H pre-hardened mold steel during tempering".MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING 709(2018):181-192.