High-Temperature Decomposition Mechanism of M<sub>2</sub>C Primary Carbide in M50 Steel

doi:10.11900/0412.1961.2023.00106

IMR OpenIR

	High-Temperature Decomposition Mechanism of M₂C Primary Carbide in M50 Steel
	Ma Fang 1,2; Lu Xingyu 3; Zhou Lina 2; Du Ningyu 3; Lei Chengshuai 3; Liu Hongwei 3; Li Dianzhong 3
通讯作者	Lei Chengshuai(cslei@imr.ac.cn) ; Liu Hongwei(hwliu@imr.ac.cn)
	2024-07-11
发表期刊	ACTA METALLURGICA SINICA
ISSN	0412-1961
卷号	60 期号:7 页码:901-914
摘要	M50 steel is primarily used for manufacturing the main shaft bearings of aero engines. However, the fatigue property of M50 steel affects the service life of shaft bearings owing to their operation in the environment with high temperature, high rotation speed, and high contact stress. Inclusions and large-sized carbides are proved to be the primary reasons that cause fatigue cracking. Nevertheless, inclusions in M50 steel and fatigue failure due to inclusions are substantially reduced with the rapid development of metallurgical technology and metallurgical equipment in recent years. M50 steel contains high fractions of Cr, Mo, and V elements, which are easily enriched and can form primary carbides. The primary carbides in M50 steel are hard and brittle and cause stress concentration under external load, thereby accelerating the initiation and propagation of fatigue cracks. Currently, the large-sized primary carbides in M50 steel play an important role in reducing the service life of bearings and have attracted substantially research attention. The present investigation focuses on the decomposition mechanism of large-sized M2C primary carbide in M50 steel to reveal the carbide-refinement mechanism during high-temperature heat treatment. In addition, M2C primary carbide in M50 steel was systematically characterized by SEM, EPMA, and TEM, and its decomposition mechanism at 1160-1250 degrees C was studied. The difference in chemical composition of different M2C primary carbides and its effect on the decomposition mechanism were also explored. Three forms of M2C carbides in M50 steel were revealed: the rod-like carbide, the lamellar-like carbide, and the block-like carbide. In these three M2C carbides, the content of Fe increased, while the content of Mo decreased successively. The difference in chemical composition and morphology of these three M2C carbides led to the different microstructure-evolution process when heat-treated at elevated temperature. When the steel was heat-treated at 1160-1180 degrees C, only the M2C carbides with high Fe content decomposed and a few of the carbides transformed to MC carbide. The growth rate of MC carbide was extremely low at this temperature. When the steel was heat-treated at 1210 degrees C, most of the M2C carbides decomposed after 20 h. The growth rate of MC carbide also increased rapidly, and a large amount of large-sized MC carbides were found. Further heat treatment of steel at 1250 degrees C resulted in the decomposition of all M2C carbides and the absence of large-sized primary carbides in the microstructure. However, a large amount of newly born M2C carbide, formed due to the melting of the matrix and re-solidification, were found in the microstructure.
DOI	10.11900/0412.1961.2023.00106
收录类别	SCI
语种	英语
WOS研究方向	Metallurgy & Metallurgical Engineering
WOS类目	Metallurgy & Metallurgical Engineering
WOS记录号	WOS:001260210800005
出版者	SCIENCE PRESS
引用统计	被引频次：1[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/321006/187971
专题	中国科学院金属研究所
通讯作者	Lei Chengshuai; Liu Hongwei
作者单位	1.Harbin Inst Technol, Sch Mechatron Engn, Harbin 150001, Peoples R China 2.AECC Harbin Bearing Co Ltd, Harbin 150025, Peoples R China 3.Chinese Acad Sci, Shenyang Natl Lab Mat Sci, Inst Met Res, Shenyang 110016, Peoples R China
推荐引用方式 GB/T 7714	Ma Fang,Lu Xingyu,Zhou Lina,et al. High-Temperature Decomposition Mechanism of M₂C Primary Carbide in M50 Steel[J]. ACTA METALLURGICA SINICA,2024,60(7):901-914.
APA	Ma Fang.,Lu Xingyu.,Zhou Lina.,Du Ningyu.,Lei Chengshuai.,...&Li Dianzhong.(2024).High-Temperature Decomposition Mechanism of M₂C Primary Carbide in M50 Steel.ACTA METALLURGICA SINICA,60(7),901-914.
MLA	Ma Fang,et al."High-Temperature Decomposition Mechanism of M₂C Primary Carbide in M50 Steel".ACTA METALLURGICA SINICA 60.7(2024):901-914.