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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–*** 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 *** situ observation on the experimental steel by high-temperature confocal laser scanning microscopy confirms that MgO can provide nucleation sites for *** addition,the MgS·MnS and MgO–MgS·MnS inclusions can also provide positions for the nucleation of *** 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 *** the same time,MgS precedes TiN precipitates in the solid–liquid two-phase region;thus,MgO and MgS·MnS can provide sites for TiN *** 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

Investigation on the oil transfer behaviors and the air–oil interfacial flow patterns in a ball bearing under different capillary conditions

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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

Dense-Structured Network Based bearing Remaining Useful Life Prediction System

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Computer Modeling in Engineering & Sciences 2022年第10期131卷 133-151页

作者： Ping-Huan Kuo Ting-Chung Tseng Po-Chien Luan Her-Terng Yau Department of Mechanical Engineering National Chung Cheng UniversityChiayi62102Taiwan Advanced Institute of Manufacturing with High-Tech Innovations(AIM-HI) National Chung Cheng UniversityChiayi62102Taiwan

This work is focused on developing an effective method for bearing remaining useful life *** method is useful in accurately predicting the remaining useful life of bearings so that machine damage,production outage,and human accidents caused by unexpected bearing failure can be *** study uses the bearing dataset provided by FEMTO-ST Institute,Besancon,*** study starts with the exploration of neural networks,based on which the biaxial vibration signals are modeled and *** paper introduces pre-processing of bearing vibration signals,neural network model training and adjustment of training *** model is trained by optimizing model parameters and verifying its performance through *** proposed model’s superiority is also confirmed through a comparison with other *** this study,the neural network model is trained with various types of bearing data and can successfully predict the remaining useful *** algorithm proposed in this study achieves a prediction accuracy of coefficient of determination as high as 0.99.

关键词： bearing neural network remaining useful life prediction machine learning

A Novel Deep Model with Meta-Learning for Rolling bearing Few-Shot Fault Diagnosis

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Journal of Dynamics, Monitoring and Diagnostics 2023年第2期2卷 102-114页

作者： Xiaoxia Liang Ming Zhang Guojin Feng Yuchun Xu Dong Zhen Fengshou Gu College of Mechanical Engineering Hebei University of Science and TechnologyTianjin 300401China Advanced Equipment Research Institute Co. Ltd.of HEBUTTianjinChina College of Engineering and Physical Sciences Aston UniversityBirmingham B47ETUK Centre for Efficiency and Performance Engineering University of HuddersfieldQueensgateHuddersfield HD13DHUK

Machine learning,especially deep learning,has been highly successful in data-intensive applications;however,the performance of these models will drop significantly when the amount of the training data amount does not meet the *** leads to the so-called few-shot learning(FSL)problem,which requires the model rapidly generalize to new tasks that containing only a few labeled *** this paper,we proposed a new deep model,called deep convolutional meta-learning networks,to address the low performance of generalization under limited data for bearing fault *** essential of our approach is to learn a base model from the multiple learning tasks using a support dataset and finetune the learnt parameters using few-shot tasks before it can adapt to the new learning task based on limited training *** proposed method was compared to several FSL methods,including methods with and without pre-training the embedding mapping,and methods with finetuning the classifier or the whole model by utilizing the few-shot data from the target *** comparisons are carried out on 1-shot and 10-shot tasks using the Case Western Reserve University bearing dataset and a cylindrical roller bearing *** experimental result illustrates that our method has good performance on the bearing fault diagnosis across various few-shot *** addition,we found that the pretraining process does not always improve the prediction accuracy.

关键词： bearing deep model fault diagnosis few-shot learning meta-learning

bearing capacity and mechanical behavior of CFG pile composite foundation

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Journal of Central South University 2008年第S2期15卷 45-49页

作者：陈秋南赵明华周国华张主华 Geotechnical Institute Hunan University School of Civil Engineering Hunan University of Science and Technology

CFG pile (i.e., pile constructed by granular materials of cement, fly-ash and gravel) composite foundation is applied in subsoil treatment widely and successfully. In order to have a further study of this kind of subsoil treatment technology, the influencing factors and calculation methods of the vertical bearing capacity of single CFG pile and the CFG pile composite foundation were discussed respectively. And based on the obtained solutions, effects by the cushion and measurements to reduce negative friction area were analyzed. Moreover, the developing law of settlement and bearing capacity eigenvalue controlled by the material strength with the increase of load were given for the CFG composite foundation. The in-situ static load test was tested for CFG pile. The results of test show that the maximum test load or half of the ultimate load is used from all the points of test, the average bearing capacity eigenvalue of single pile is 390 kN, and slightly greater than the design value of bearing capacity. The bearing capacity eigenvalues of composite foundation for 3 piles are greater than 300 kPa, and the mechanical properties of CFG pile composite foundation are almost identical in the case of the same load and cushion thickness. The pile-soil stress ratio and the load-sharing ratio can be adjusted through setting up cushion thickness.

关键词： CFG pile composite foundation properties of bearing capacity in-situ static load pile-soil stress ratio

Numerical study on variation characteristics of the unsteady bearing forces of a propeller with an external transverse excitation

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Journal of Hydrodynamics 2019年第2期31卷 400-412页

作者： Min-hua Shu Ke Chen Yun-xiang You Tian-qun Hu Remfeng Wang State Key Laboratory of Ocean Engineering Collaboration Innovation Center for Advanced Ship and Deep-Sea Exploitation EquipmentShanghai JiaoTong UniversityShanghai 200240China

The unsteady bearing forces of a propeller can be significantly affected by external transverse *** paper numerically studies the unsteady variation characteristics of the bearing forces of a three-blade conventional propeller with external transverse excitations or without *** dynamic mesh method combined with the RANS turbulence model is *** numerical simulation shows the frequency response in the frequency domain of KT,Kq under external transverse *** frequency of the response is found always equal to twice of the excitation *** the amplitude of the external transverse excitation keeps constant,the amplitude of the response increases with the in crease of the excitation *** the excitation frequency keeps constant,the amplitude of the response increases with the increase of the excitation amplitude,in a power-law *** pressure distribution can be significantly affected by the external transverse excitation,leading to a high irregularity of the flow field.

关键词： External transverse excitation unsteady bearing forces excitation frequency propeller dynamic mesh method

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 *** experimental results showed that the lath martensite was obtained by quenching and a few twins as substructures formed in some martensitic *** 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 *** phenomenon is due to the increase in internal stress caused by cryogenic *** tempering,the rudiment of sub-interface further evolved into the martensitic lath boundary,and thus the original martensitic laths were *** twins formed by cryogenic treatment did not disappear after *** addition,small quantities of annealing twins formed in tempering *** 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

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 *** experiment of continuous casting of the steel was carried out by using a continuous casting physical simulation apparatus with the final electromagnetic *** liquid core profile was revealed by the pour-out method during the solidification *** ingots were produced under different electromagnetic stirring parameters for *** 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 *** 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 *** 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

Effect of Prior Cold Deformation on the Stability of Retained Austenite in GCr15 bearing Steel

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Acta Metallurgica Sinica(English Letters) 2019年第1期32卷 107-115页

作者： Feng Wang Dong-Sheng Qian Xiao-Hui Lu School of Materials Science and Engineering Wuhan University of Technology Hubei Key Laboratory of Advanced Technology for Automotive Components School of Automotive Engineering Wuhan University of Technology

In this work, the effect of prior cold deformation on the stability of retained austenite in GCr15 bearing steel was investigated after quenching and tempering treatment. The thermal stability was evaluated by calculating thermal activation energy for decomposition of retained austenite using differential scanning calorimeter. The mechanical stability was investigated according to the strain-induced martensitic transformation behavior of retained austenite under the standard compression testing. It is found that the prior cold deformation not only accelerates the carbide dissolution during the austenitization process but also contributes to the carbon partitioning in the tempering stage due to the higher density of phase boundaries, which results in the improvement of the thermal stability of retained austenite. Due to the enhanced carbide dissolution, the higher carbon content in the prior austenite will intensify the isotropic strain of martensitic transformation. As a consequence, the film-like retained austenite is likely to form under a higher hydrostatic pressure and thus shows a higher mechanical stability. Additionally, it is noteworthy that the benefits of the prior cold deformation to the stability of retained austenite would be saturated when the cold deformation degree is larger than 40%.

关键词： GCr15 bearing steel Prior cold deformation Retained austenite stability