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Formation of internal cracks during soft reduction in rectangular bloom continuous casting

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International Journal of Minerals,Metallurgy and Materials 2012年第1期19卷 21-29页

作者： Xiao-bin Li Hua Ding Zheng-you Tang Ji-cheng He School of Materials and Metallurgy Northeastern University Shenyang 110819 China The Key Laboratory of the Ministry of Education for Electromagnetic Processing of Materials Northeastern University Shenyang 110819 China

To investigate the formation of internal cracks in GCrl 5 bearing steels during the soft reduction process in rectangular bloom con- tinuous casting, fully coupled thermomechanieal finite element models were developed using the commercial software MSC.MARC, and microstructures and fractographs were also observed. With the finite element models, the contours of temperature, equivalent plastic strain, and equivalent vun Mises stress were simulated. It is observed that the fracture surfaces of internal cracks are covered by cleavage or quasi-cleavage facets. The region of internal cracks in the intergranular brittle fracture mode is in the mushy zone between the zero ductility temperature （ZDT） and the zero strength temperature （ZST）. The simulated equivalent plastic strain in the crack region is 2.34%-2.45%, which is larger than the critical strain （0.4%-1.5%）, and the equivalent von Mises stress is 1.84-5.05 MPa, which is within the range of criti- cal stress （3.9-7.2 MPa）, thus resulting in the occurrence of internal cracks. Reducing the soft reduction amount from 3 to 2 mm can lower the stress under the critical value.

关键词： bearing steel rectangular blooms soft reduction finite element method internal cracks

Study on Oxygen Content, Inclusions and Fatigue Properties of bearing steels Produced by Different Processes

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Journal of University of Science and Technology Beijing 2001年第1期8卷 25-27页

作者： Deguang Zhou Jie Fu Xichun Chen Jing Li Metallurgy School, University of Science and Technology-Beijing, Beijing 100083, China Metallurgy School Univ. of Science/Technology-Biejing Beijing 100083 China

The metallurgical properties and fatigue life of bearing steel processed by electric furnace (EAF), ladle refining (LF-VD), continous casting (CC) and electroslag remelting (ESR) have been investigated. The main results obtained are as follows: (1) Due to low oxygen content and dispersion inclusions in steel, the fatigue Life of LF-VD-IC or CC is three times as high as that of EAF steel; (2) The oxygen content in steel produced by CC process is about 9.0x10(-6), the carbon segregation (C/C(0)) is from 0.92 to 1.10 and the fatigue life of CC steel is equal to that of ladle refining ingot casting steel; (3) Although the amount of inclusion and oxygen in ESR steel is higher than that of LF-VD-IC or CC steel, the fatigue life of ESR steel is higher than that of the latter because of its fine and well dispersed inclusions.

关键词： bearing steel ladle refining continuous casting electroslag remelting oxygen content inclusion fatigue life

Effect of Electromagnetic Stirring on Molten steel Flow and Solidification in Bloom Mold

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Journal of Iron and steel Research(International) 2014年第12期21卷 1095-1103页

作者： Zhen-guo YANG Bao WANG Xiao-feng ZHANG Ya-tao WANG Hong-biao DONG Qing LIU State Key Laboratory of Advanced Metallurgy University of Science and Technology Beijing Special steel Plant Laiwu Iron and Steel Co.Ltd. Department of Engineering University of Leicester

The effect of electromagnetic stirring on molten steel flow and heat transfer in a 260 mm× 300 mm bloom mold was investigated by using a method combining both finite element method and finite volume method. The simu lation results related to magnetic fields were consistent with the onsite measured data. The magnetic flux density in creased with increasing the current intensity but decreased with increasing the current frequency. Electromagnetic stirring caused molten steel to flow with rotation on a horizontal section and two sets of recirculation regions with opposite fellow directions in a longitudinal section formed. The maximum tangential velocity increased with increasing the current intensity and frequency. Furthermore, the superheat degree of the molten steel on the outlet cross section of the mold decreased with increasing the current intensity. growth zone of solidified shell in the effective stirring zone. bearing steel, the appropriate values of current intensity and to be 300 A and 3 Hz, respectively. Electromagnetic stirring caused the emergence of a zero For the 260 mm N 300 mm bloom continuous caster of current frequency of electromagnetic stirring were found

关键词： bloom mold electromagnetic stirring flow heat transfer numerical simulation bearing steel

Improvement　of　K_(IC)　and　ΔK_(th)　for　steel　GCr15　by　SL　Technology

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Journal of Iron and steel Research(International) 1997年第1期4卷 42-45页

作者： Yang YulinYanshan University, Qinhuangdao (066004), China, Huang QingHarbin Heavy Machinery Factory, Harbin (150014), China Yanshan University Qinhuandao 066001 China

The inclusion of steel GCr15 using SL and CAB technologies has been investigated and determined with SEM and optical microscope. The K IC and Δ K th of steel GCr15 were measured with the method of fracture mechanics. Experimental results show that the volume fraction of inclusion and the large particle inclusion can be reduced by using SL technology. Both values of K IC and Δ K th with SL technology were higher than those with CAB technology to some extent. It is feasible to measure Δ K th of steel GCr15 with lift drop method for multiple specimens.

关键词： ladle injection bearing steel fracture toughness

Numerical Simulation of Electro-slag Remelting Process Solidification Structure of Cr-Co-Mo-Ni bearing steel

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Numerical Simulation of Electro-slag Remelting Process Solid...

Inclusions Control in High-quality bearing steels based on the Prediction of Fatigue Life

中国材料大会2012

作者： Liguo Bai Maosheng Yang Jingshe Li University of Science & Technology Beijing Central Iron & steel Research Institute

ISBN: (纸本)9783037856093

The solidification microstructure and crystallization of Cr-Co-Mo-Ni bearing steel were simulated in solidification process based on CAFE methods in the electro-slag remelting process.The optimization of the intensity of cooling and molten pool temperature was simulated for Cr-Co-Mo-Ni bearing steel.The result shows that raising the cooling intensity to 7.5 m 3 /h and reducing the superheat temperature to 1600℃ can increase the grain nucleation number about 13.83%,and reduce the average columnar grain radius about 10.61%,to have a very good effect on refining the grains and get dense uniform solidification,which improve the homogeneity of the solidification structure,and reduce the performance differences of the materials.

关键词： bearing steel CAFE Electro-slag Remelting Numerical Simulation Solidification Intensity of Cooling Molten Pool Temperature.

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Inclusions Control in High-quality Bearing Steels based on t...