Optimum Composition of CaO-SiO2-Al2O3-MgO Slag for Spring Steel Deoxidized by Si and Mn in Production

Yang, Hailong; Ye, Jiansong; Wu, Xiaoliang; Peng, Yongsheng; Fang, Yi; Zhao, Xinbing

doi:10.1007/s11663-015-0581-x

“…He et al [16] showed that the inclusions are plastic at the end of the refining process, the basicity (R = wt.%CaO/wt.% SiO 2 ) of refining slag is in the range of 1.0~1.2 and the Al 2 O 3 content of slag is in the range of 3~9 wt.%. Yang et al [17] showed that the inclusions located in the low-melting-point region when the basicity was in the range of 1.00 to 1.19 had a C/A value (wt.% CaO/wt.% Al 2 O 3 ) above 9 at 1673 K. Similar results were mentioned in other studies [18][19][20].…”

Section: Introductionsupporting

confidence: 71%

Effect of Slag Adjustment on Inclusions and Mechanical Properties of Si-Killed 55SiCr Spring Steel

Li

¹

,

Chen

²

,

Hu

³

et al. 2022

Crystals

3

0

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The effects of the Al2O3 content and basicity of CaO–SiO2–Al2O3–10 wt.% MgO refining slag on inclusions removal in 55SiCr spring steel were investigated. The viscosity of slag was studied using a viscometer, while the microstructure investigation involved using a water-quenching furnace and a Fourier-transform infrared spectrometer. The influence mechanism of the slag adjustment on inclusions was explored through thermodynamic calculations and kinetic analysis. The results indicated that the viscosity of the molten slag increased gradually with the content of Al2O3 increasing due to it increasing the degree of polymerization of the slag network structure, especially the [AlO4]5− and [Si-O-Si] structures. In contrast, the viscosity of molten slag experienced the opposite pattern, with the basicity of molten slag increasing. This was due to the fact that Ca2+ can significantly reduce the degree of polymerization of a slag network structure, especially the percentages of the [SiO4]4−, [AlO4]5− and [Si-O-Si] network structures. Finally, the changes in physical properties and structure of slag significantly affected the removal effect of the inclusions in molten steel. As a result, the number, size distribution, composition distribution and morphology of the inclusions displayed significant changes when the content of Al2O3 increased from 3 wt.% to 12 wt.% and the basicity of the slag gradually increased from 0.5 to 1.2.

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“…Interaction coefficients e y x in dilute liquid iron for selected elements at 1873 K[18][19][20][21][22][23] …”

mentioning

confidence: 99%

Nitrogen and nitride non-metallic inclusions in steel

Burja¹,

Koležnik²,

Župerl³

et al. 2019

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The paper deals with the formation of coarse nitride non-metallic inclusions in steel. The thermodynamic calculations for the determination of the equilibrium solubility of nitrogen in the steel melt at a given temperature and chemical composition are presented. Some of the negative effects of excessive nitrogen contents, like blow holes, strain aging and, most importantly, nitride non-metallic inclusion formation are discussed. Five types of the coarse nitride non-metallic inclusions that occur in industrial practice are presented: aluminium, boron, niobium, titanium, and zirconium nitrides. Examples of the negative effect of coarse nitrides from case studies are also shown. The basic thermodynamic tools and values of the parameters for calculating the nitride precipitation in the steel melt are given in the paper.

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“…Therefore, the respective mass transfer resistance of metal (R M i ) and slag component (R M i O n ) can be expressed by Eq. [18], which can express the controlling step in the reactions. During the transfer of component i from molten steel to slag, the flux density should be constant, this can be expressed by Eq.…”

Section: Kinetics Of Slag-steel Reactionsmentioning

confidence: 99%

“…Based on Eq. [18], the mass transfer resistance of the respective components on the slag side can be obtained. The calculated values for mass transfer resistances of Al 2 O 3 , TiO 2 and SiO 2 are 0.23, 44 and 2.3910 4 m 2 s/kg, respectively.…”

Section: Kinetics Of Slag-steel Reactionsmentioning

confidence: 99%

“…Meanwhile, it is well known that the refining slag having a proper composition and excellent physicochemical properties can effectively modify and remove the inclusions. [16][17][18][19][20][21][22][23] It is a significant advantage that a good contact between metal and slag makes the steel chemically refined. [24] Park et al [25] investigated the effect of CaO-Al 2 O 3 -MgO slags on the formation of MgO-Al 2 O 3 inclusions in a Si deoxidized 16 mass pct Cr ferritic stainless steel.…”

Section: Introductionmentioning

confidence: 99%

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Evolution of the Non-metallic Inclusions Influenced by Slag-Metal Reactions in Ti-Containing Ferritic Stainless Steel

Wang

¹

,

Cho

²

,

Jeong

³

et al. 2021

Metall Mater Trans B

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Laboratory experiment and thermodynamic calculation for the Ti-containing 24 mass pct Cr ferritic stainless steel with a CaO-SiO2-Al2O3-MgO system slag were performed to investigate the effect of slag addition on the inclusion characteristics in molten steel. The morphology, composition, and size evolution of inclusions in steel samples were analyzed in three-dimensional by the electrolytic extraction method and in two-dimensional by the automatic analysis method. The results showed that the Ti content significantly decreased after the slag addition. However, the change of the Si content showed an opposite tendency. The decrease of the Ti content in steel was due to the reduction of SiO2 and Al2O3 in the slag by dissolved Ti in steel. An increase of the TiO2 content in the slag can decrease the Ti loss in steel based on the slag-steel kinetic analysis. The total O content in the steel melt decreased from 62 to 26 ppm, and the steel cleanliness was improved, since the number density of inclusions decreased after the slag refining. The results of a kinetic analysis showed that the rate-determining step of the oxidation of Ti in the steel and the reduction of SiO2 in the slag were the mass transfer on the slag side. In addition, high Ti2O3-containing inclusions were found to be transformed to Cr2O3-Ti2O3-Al2O3 and Cr2O3-Ti2O3-SiO2 system inclusions after the slag addition. The Al2O3 contents in inclusions increased while the Ti2O3 contents decreased with time. However, there were some amount of high melting point inclusions with high Al2O3 content, which were not what we expected. When plotted on logarcxithmic scales, the mole ratio $$X_{{{\text{Al}}_{2} {\text{O}}_{3} }} /(X_{{{\text{Ti}}_2 {\text{O}}_{3} }} \cdot X_{{{\text{Cr}}_{2} {\text{O}}_{3} }} )$$ X Al 2 O 3 / ( X Ti 2 O 3 · X Cr 2 O 3 ) values of the inclusions were expressed as a linear function of the $$a_{\text{Al}}^{2} /(a_{Ti}^{2} \cdot a_{\text{Cr}}^{2} \cdot a_{\text{O}}^{3} )$$ a Al 2 / ( a Ti 2 · a Cr 2 · a O 3 ) values of the steel melts with a slope of unity, which was theoretically expected.

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Optimum Composition of CaO-SiO2-Al2O3-MgO Slag for Spring Steel Deoxidized by Si and Mn in Production

Cited by 23 publications

References 12 publications

Effect of Slag Adjustment on Inclusions and Mechanical Properties of Si-Killed 55SiCr Spring Steel

Effect of Slag Adjustment on Inclusions and Mechanical Properties of Si-Killed 55SiCr Spring Steel

Nitrogen and nitride non-metallic inclusions in steel

Evolution of the Non-metallic Inclusions Influenced by Slag-Metal Reactions in Ti-Containing Ferritic Stainless Steel

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