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Friction 2023年第2期11卷 228-245页

作者： Hongbai CHEN He LIANG Wenzhong WANG Shengguang ZHANG School of Mechanical Engineering Beijing Institute of TechnologyBeijing 100081China Aero Engine Academy of China Beijing 101304China

Lubricant oil is crucial to the rolling bearings as the main medium of lubricating, cooling, cleaning, and so on. The oil starvation in and around the contacts is harmful to the performance and fatigue life of rolling bearings. Therefore, it is of necessity to understand the behaviors of oil transfer and the patterns of air-oil two-phase flow in bearings, especially with the influence of different capillary properties. This work established a transient air-oil two-phase flow model in a ball bearing based on computational fluid dynamics (CFD). Groups of cases are implemented to investigate the behaviors of oil transfer and air-oil flow under different capillary conditions with speed, surface tension, and viscosity. Flow patterns are classified by the morphological features of the air-oil flow. Staged phenomena are analyzed with flow patterns and reach good agreements with the observations from experiments. It is found that the oil distribution and air-oil flow behaviors in a ball bearing are strongly related to the speed and the ratio of oil viscosity and air-oil surface tension (μ_(oil/σ)). The flow maps imply that the levels of capillary number (Ca) may be the boundaries and the critical points of flow pattern transition between the different flow patterns in bearing.

关键词： flow pattern oil transfer computational fluid dynamics(CFD) bearing

Composition evolution and deformation of different non-metallic inclusions in a bearing steel during hot rolling

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Journal of Iron and Steel Research(International) 2022年第4期29卷 552-562页

作者： Nan Liu Gong Cheng Li-feng Zhang Wen Yang Ying Ren Guo-cheng Wang Xiao-ming Liu School of Metallurgical and Ecological Engineering University of Science and Technology BeijingBeijing 100083China Steelmaking Plant Baotou Steel Union Co.Ltd.Baotou 014010Inner MongoliaChina Engineering Technology Co. Ltd.WISDRI Engineering and Research Incorporation LimitedWuhan 430223HubeiChina School of Mechanical and Materials Engineering North China University of TechnologyBeijing 100144China School of Materials and Metallurgy University of Science and Technology LiaoningAnshan 114051LiaoningChina

The composition evolution and deformation of different non-metallic inclusions in a bearing steel during hot rolling were investigated by the automatic detection and the improved non-aqueous electrolysis method.Manganese sulfide,MnS–TiN,and liquid CaO–Al_(2)O_(3) inclusions were elongated while TiN and MgO-Al_(2)O_(3) were fractured during hot rolling.The CaS–MnS phase in the MgO–Al_(2)O_(3)–CaS–MnS inclusion was separated from the inclusion,leading to the formation of CaS–MnS type clusters.Meanwhile,the CaS and MnS contents in oxide-containing inclusions decreased while the MgO and Al_(2)O_(3) contents increased after hot rolling.The deformability of different inclusions in the bearing steel was quantitatively compared and discussed.

关键词： bearing steel Hot rolling Composition evolution Deformability Inclusion

Effect of Mg addition on TiN inclusions in GCr15 bearing steel

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Journal of Iron and Steel Research(International) 2022年第6期29卷 925-938页

作者： Lei Cao Guo-cheng Wang Yuan-you Xiao Rong-guang Yang School of Materials and Metallurgy University of Science and Technology LiaoningAnshan 114051LiaoningChina Key Laboratory of Metallurgy Engineering Liaoning Province University of Science and Technology LiaoningAnshan 114051LiaoningChina Steel Rolling Department Shougang Jingtang United Iron and Steel Co.Ltd.Tangshan 063200HebeiChina

Compared with the original GCr15 bearing steel,TiN inclusions are greatly reduced by the effect of Mg addition,and many different types of non-metallic Mg-containing inclusions were observed in Mg-treated GCr15 bearing steel which includes MgO,MgS·MnS,MgO–MgS·MnS,MgAl_(2)O_(4)–MgS·MnS,MgO–TiN,MgS·MnS–TiN,and MgO–MgS·MnS–TiN.The inclusion size distribution based on automatic inclusion analysis software shows that the number of inclusion with the size ranging from 1 to 3μm increases obviously because a large amount of MgO,MgS·MnS,TiN inclusions containing Mg with smaller sizes are massively generated.In situ observation on the experimental steel by high-temperature confocal laser scanning microscopy confirms that MgO can provide nucleation sites for TiN.In addition,the MgS·MnS and MgO–MgS·MnS inclusions can also provide positions for the nucleation of TiN.Thermodynamic calculations indicate that after Mg addition to liquid steel,a large number of fine MgO inclusions are generated in the liquid steel because of the strong reactivity of Mg and O.At the same time,MgS precedes TiN precipitates in the solid–liquid two-phase region;thus,MgO and MgS·MnS can provide sites for TiN nucleation.At last,two possible formation pathways for the above various TiN inclusions containing Mg are discussed.

关键词： Mg treatment GCr15 bearing steel TiN inclusion Size distribution In situ observation

Effect of deep cryogenic treatment on martensitic lath refinement and nano-twins formation of low carbon bearing steel

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Journal of Iron and Steel Research(International) 2020年第1期27卷 105-113页

作者： Xin-yang Lü Zhi-wei Wu Xiao He Jun Li Shao-hong Li Mao-sheng Yang Kun-yu Zhao Faculty of Material Science and Engineering Kunming University of Science and TechnologyKunming 650093YunanChina Institute for Special Steels Central Iron and Steel Research InstituteBeijing 100081China

The effect of heat treatment and deep cryogenic treatment on microstructural evolution of low carbon martensitic bearing steel was investigated.The experimental results showed that the lath martensite was obtained by quenching and a few twins as substructures formed in some martensitic laths.The rudiment of sub-interfaces of martensitic lath was formed in the highdensity dislocation regions after deep cryogenic treatment;meanwhile,the number of twins increased,especially in the highdensity dislocation regions.This phenomenon is due to the increase in internal stress caused by cryogenic treatment.After tempering,the rudiment of sub-interface further evolved into the martensitic lath boundary,and thus the original martensitic laths were refined.The twins formed by cryogenic treatment did not disappear after tempering.In addition,small quantities of annealing twins formed in tempering process.Martensitic laths morphology and substructures in different stages of the heat and deep cryogenic treatment were observed by tninsmission electron microscopy.

关键词： Low carbon bearing steel-Deep cryogenic treatment Internal stress Sub-interface Nano-twin

Impact of climate change on allowable bearing capacity on theQinghai-Tibetan Plateau

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Advances in Climate Change Research 2019年第2期10卷 99-108页

作者： XU Xiao-Ming WU Qing-Bai State Key Laboratory of Frozen Soil Engineering Northwest Institute of Eco-Environment and Resources Chinese Academy o f Sciences Lanzhou 730000 China

Climate change has a substantial impact on infrastructures in the permafrost on the Qinghai-Tibetan Plateau (QTP). In this study, the mean annual ground temperature (MAGT) and permafrost evolution were investigated in both the historical (1950-2005) and projected (2006-2099) periods. Then, an allowable bearing capacity model was used to discuss the allowable bearing capacity change on the QTP. Results show that the MAGT increased by 0.36 ℃ during 1950-2005. The MAGT will increase by 0.40 (RCP2.6), 0.79 (RCP4.5), 1.07 (RCP6.0), and 1.75 (RCP8.5)℃C during 2006-2099. In addition, the permafrost area has decreased by 0.195 × 10^6 km2 in 1950-2005. The permafrost area will decrease by 0.232 × 10^6 (RCP2.6), 0.468 × 10^6 (RCP4.5), 0.564 × 10^6 (RCP6.0), and 0.803 × 10^6 (RCP8.5) km2 during 2006-2099. With the degradation of permafrost, the allowable bearing capacity in permafrost zones would decrease accordingly. The decreasing trend is 6 kPa per 10 years in 1950-2005, and will be 0.6 (RCP2.6), 5 (RCP4.5), 7 (RCP6.0), and 11 (RCP8.5) kPa per 10 years during 2006-2099. The most remarkable trend would be observed under RCP8.5. Meanwhile, some scientific advices for the design, construction, operation and maintenance of permafrost engineering in the context of climate change were provided.

关键词： Qinghai-Tibetan Plateau Climate change Permafrost Allowable bearing capacity

Effect of final electromagnetic stirring on solidification microstructure of GCr15 bearing steel in simulated continuous casting

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Journal of Iron and Steel Research(International) 2020年第2期27卷 141-147页

作者： Dan-qing Jiang Rui Wang Qiong Zhang Zhen-qiang Zhang Ting-sheng Tu Jiang Wang Zhong-ming Ren School of Materials Science and Engineering Shanghai UniversityShanghai 200444China State Key Laboratory of Advanced Special Steel Shanghai UniversityShanghai 200444China

The effect of final electromagnetic stirring on the solidification structure,element segregation,and carbides of GCrl5 bearing steel was investigated.The experiment of continuous casting of the steel was carried out by using a continuous casting physical simulation apparatus with the final electromagnetic stirring.The liquid core profile was revealed by the pour-out method during the solidification process.Eight ingots were produced under different electromagnetic stirring parameters for comparison.The results show that,at the final stage of solidification,intense electromagnetic stirring exacerbates the central carbon segregation,resulting in more serious precipitation of the primary carbides.It is also found that the carbides in the segregation area are dominantly M3C type,together with a small amount of M7C3-type and M3C2-type carbides.In this physical simulation model,the optimal stirring parameters to obtain a fine and homogeneous structure are the liquid pool width of 15 mm,current intensity of 150 A,and stirring frequency of 5 Hz.

关键词： GCrl5 bearing steel Solidification structure Continuous casting Final electromagnetic stirring Segregation Carbide

A new bearing fault diagnosis method based on modified convolutional neural networks

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Chinese Journal of Aeronautics 2020年第2期33卷 439-447页

作者： Jiangquan ZHANG Yi SUN Liang GUO Hongli GAO Xin HONG Hongliang SONG School of Mechanical Engineering Southwest Jiaotong UniversityChengdu 610031China

Fault diagnosis is vital in manufacturing system.However,the first step of the traditional fault diagnosis method is to process the signal,extract the features and then put the features into a selected classifier for classification.The process of feature extraction depends on the experimenters’experience,and the classification rate of the shallow diagnostic model does not achieve satisfactory results.In view of these problems,this paper proposes a method of converting raw signals into twodimensional images.This method can extract the features of the converted two-dimensional images and eliminate the impact of expert’s experience on the feature extraction process.And it follows by proposing an intelligent diagnosis algorithm based on Convolution Neural Network(CNN),which can automatically accomplish the process of the feature extraction and fault diagnosis.The effect of this method is verified by bearing data.The influence of different sample sizes and different load conditions on the diagnostic capability of this method is analyzed.The results show that the proposed method is effective and can meet the timeliness requirements of fault diagnosis.

关键词： bearing Convolutional neural networks Different load domains Fault identification Raw signals Fault diagnosis

Effects of rare earth elements on inclusions and impact toughness of high-carbon chromium bearing steel

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Journal of Materials Science & Technology 2019年第7期35卷 1298-1308页

作者： Chaoyun Yang Yikun Luan Dianzhong Li Yiyi Li Institute of Metal Research Chinese Academy of SciencesShenyang110016China School of Materials Science and Engineering University of Science and Technology of ChinaHefei230026China

High-carbon chromium bearing steels with different rare earth (RE) contents were prepared to investigate the effects of RE on inclusions and impact toughness by different techniques. The results showed that RE addition could modify irregular Al2O3 and MnS into regular RE inclusions. With the increase of RE content, the reaction sequence of RE and potential inclusion forming elements should be O, S, As, P and C successively. RE inclusions containing C might precipitate in molten steel and solid state, but the precipitation tem perature was significantly higher than that of carbides in high-carbon chromium bearing steel. For experim ental bearing steels, the volume fraction of inclusions increased steadily with the increase of RE content, but smaller and more dispersed inclusions could be obtained by 0.018% RE content compared with bearing steel without RE, whereas the continuous increase of RE content led to an increasing trend for inclusion size and a gradual deterioration for inclusion distribution. RE addition could improve the transverse impact toughness and isotropy of bearing steel, and for modified highcarbon chrom ium bearing steel by RE alloying, the increase of RE content continuously increased both transverse and longitudinal im pact toughness until excessive RE addition.

关键词： High-carbon chromium bearing steel Rare earth Inclusions Impact toughness

Influence of abnormal stress under a residual bearing coal pillar on the stability of a mine entry

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International Journal of Mining Science and Technology 2017年第6期27卷 945-954页

作者： Kang Jizhong Shen Wenlong Bai Jianbiao Yan Shuai Wang Xiangyu Li Wenfeng Wang Ruofan School of Mines China University of Mining & Technology School of Energy Science and Engineering Henan Polytechnic University Mewbourne School of Petroleum and Geological Engineering University of Oklahoma

Mine entries close to residual bearing coal pillars(RBCPs) will suffer large deformation that may cause rock burst. To better understand the deformation mechanism and develop safe and practical guidelines for entry design, most studies focus on the absolute size of the stress field in and around the pillar. In this paper, we present a new approach to analyze the abnormal stress field close to a RBCP that uses the stress concentration coefficient(SCC), stress gradient(SG), and coefficient of lateral pressure(CLP) to describe the stress state induced by the RBCP. Based on elastic theory and a mathematical model for the abutment stress in the RBCP, an analytical solution for the abnormal stress in the strata below the RBCP was derived and the characteristics of the abnormal stress for a case study of a coal mine in China were analyzed. The results show that the abnormal stress field around the pillar is characterized by four distinct zones: a zone of high SCC, high SG, and CLP less than 1, a zone of high SCC, low SG, and CLP less than 1, a zone of low SCC, SG close to 0, and CLP greater than 1, and a zone of SCC close to 1, SC close to 0, and CLP close to 1. Based on this zoning pattern, a numerical model was established to study the combined effects of the abnormal stress on the stability of the entry. The most stable zone was determined based on a model of the Xinrui coal mine and verified by field measurements at the mine. Our conclusions can be used as guidelines for designing safe entry layouts in similar geological and mining settings.

关键词： Residual bearing coal pillar Abnormal stress Entry layout Mechanical analysis Numerical computation

Development of and Perspective on High-Performance Nanostructured Bainitic bearing Steel

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Engineering 2019年第2期5卷 319-328页

作者： Fucheng Zhang Zhinan Yang State Key Laboratory of Metastable Materials Science and Technology Yanshan University Qinhuangdao 066004 China National Engineering Research Center For Equipment and Technology of Cold Strip Rolling Yanshan University Qinhuangdao 066004 China

bearings are the most important component of nearly all mechanical equipment, as they guarantee the steady running of the equipment, which is especially important for high-end equipment such as highspeed trains and shield tunneling machines. Requirements regarding the quality of bearings are increasing with the rapid development in technology. A country’s bearings manufacturing level directly reflects the level of that country’s steel metallurgy and machinery manufacturing. The performance of the bearing steel is the critical factor that determines the quality of a bearing. The development of new bearing steel with higher performance is the ambition of material researchers and the expectation of the manufacturing industry. Many famous bearing manufacturing enterprises are competing to develop the new generation of bearing steel. Nanostructured bainitic bearing steel (NBBS), which is a newly developed bearing steel, not only possesses high strength and toughness, but also exhibits excellent wear resistance and rolling contact fatigue (RCF) resistance. In recent years, relevant achievements in NBBS in China have led to significant progress in this field. NBBS was first used in China to manufacture large bearings for wind turbines and heavy-duty bearings, with excellent performance. As a result, NBBS and its corresponding heat-treatment process have been included in the national and industry standards for the first time. The bearing industry considers the exploitation of NBBS to be epoch-making, and has termed this kind of bearing as the second generation of bainitic bearing. In this paper, the development of NBBS is reviewed in detail, including its advantages and disadvantages. Further research directions for NBBS are also proposed.

关键词： Nanostructured bainitic bearing steel bearing steel Nanostructured bainite Development