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- 저자 : Guoguang Cheng (검색결과 3 건)
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Jinlong Lu,Guoguang Cheng,Julong Che,Liansheng Wang,Guojian Xiong 대한금속·재료학회 2019 METALS AND MATERIALS International Vol.25 No.2
In this paper, the characteristics of tensile fractures and the typical inclusions in as-cast blooms and as-rolled bars are carefullyinvestigated to figure out the causes of different transverse tensile properties in two commercial non-quenched andtempered steels. In low Ca bearing steel (3 ppm), MgO–Al2O3 (MA) + MnS are main inclusions and MA oxides expresshigh ability for MnS heterogeneous nucleation. Consequently, the MnS inclusions in as-rolled bars are larger in size andsmaller in number, the transverse ductility is satisfied due to the high space distance between the MnS inclusions. However,the transverse ductility of high Ca bearing steel (9 ppm) is much poor because MnS inclusions are agminated in distribution,causing severe stress concentration. The calculation results show that CaO in CaO–MgO–Al2O3 oxides (CMA) wouldreact with Al and S in molten steels, suppressing the formation of MnS inclusions on surface of CMA oxides. An integratedillumination including the evolution processes of typical oxides in molten steels, the generation behaviors of MnS duringthe solidification, the deformation behaviors of sulfides and the relationship between sulfides and crack initiation have beenconducted based on observation results and thermodynamic calculation.
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Yao Li,Guoguang Cheng,Jinlong Lu,Hu Long 대한금속·재료학회 2023 METALS AND MATERIALS International Vol.29 No.4
In this paper, in order to identify the formation mechanism of duplex (Ca,Mn)S inclusions in steel, based on the two heats ofcommercial Ca-treated resulfurized steel, the characteristics of duplex (Ca,Mn)S inclusions in bars, blooms and CaO-Al2O3oxides in molten steel were observed and analyzed. The results indicate that there are three types of duplex (Ca,Mn)S inclusionsin steel. The first type with over 20% Ca in (Ca,Mn)S is named as “Type-C”, the second with 4–20% Ca in (Ca,Mn)Sis named as “Type-MC” and the third with below 4% Ca in (Ca,Mn)S is named as “Type-M”. Their core oxides are mainlyCa-Mg–Al-O oxides. The aspect ratios of duplex (Ca,Mn)S inclusions in bars decrease as Ca content in (Ca,Mn)S increases. From Type-M to Type-C, CaO content in core oxides increases, and Ca content in wrapping (Ca,Mn)S increases. The shapeof duplex (Ca,Mn)S inclusions can be controlled through controlling CaO content in core oxides. During solidification,CaO-Al2O3 oxides become as heterogeneous nucleation cores of MnS inclusions, duplex (Ca,Mn)S inclusions forming inthis way, and Ca in wrapping (Ca,Mn)S come from CaO in core oxides. The higher CaO content in core oxides, the higherCa content in wrapping (Ca,Mn)S. Under the condition with specific Ca/S ratio in steel, to obtain more duplex (Ca,Mn)Sinclusions, numbers of Type-C should be decreased, and numbers of Type-MC and Type-M should be increased. To achievethis goal, the key is to obtain larger numbers of CaO-Al2O3 oxides with lower CaO and smaller sizes in molten steel.
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Wang Xiaoguang,Yin Hao,Liu Cheng,Li Xiaofeng,Zhang Guoguang,Liu Yi,Xu Wei 대한전기학회 2023 Journal of Electrical Engineering & Technology Vol.18 No.5
The rotor leakage flux will cause a lot of eddy current losses in the windings of coreless axial flux permanent magnet synchronous machine (CAFPMSM). This article presents a rotor leakage flux adjustment method for the CAFPMSM based on U-shaped iron, which can also achieve the optimization of the rotor flux field. The U-shaped iron can reduce the leakage flux crosses the winding and improve the spatial harmonic distribution of the air gap field at the same time. Firstly, the basic topology and its operating principle are investigated by using an equivalent magnetic circuit model. And then, the characteristics of the flux field distribution in the winding area are analyzed, and the parameters of the U-shaped iron on the leakage flux path regulation are elaborated and optimized by the three-dimensional finite-element method (3D FEM) analysis. Finally, the comprehensive experimental results show that the leakage flux path of the rotor passes through the U-shaped magnetically conductive block rather than through the windings, the total harmonic distortion (THD) of the air gap flux density waveform can be significantly decreased, and the THD of the back EMF and the eddy current losses are lower than before.
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