Agglomeration of Non-metallic Inclusions at Steel/Ar Interface: In - Situ Observation Experiments and Model Validation
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IT is well known that the control of the nonmetallic inclusions in steel is vital due to the increasing demands of high-quality steel grades. Steelmakers aim to produce steel with less inclusions in order to reduce nozzle clogging during continuous casting and improve mechanical properties in the final product.[1,2] The concept of inclusion engineering has been applied in the field of ferrous process metallurgy.[3] This concept deals with the control of the amount, morphology, size distribution, and composition of nonmetallic inclusions formed in liquid metal during refining and solidification. Moreover, argon bubbling is considered as an important method for removing nonmetallic inclusions from liquid
WANGZHONG MU, NESLIHAN DOGAN, and KENNETH S. COLEY are with the Department of Materials Science and Engineering, McMaster Steel Research Centre, McMaster University, 1280 Main Street West, Hamilton, ON L8S 4L7, Canada. Contact email: [email protected] Manuscript submitted January 23, 2017.
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steel,[4] because the flotation of inclusions is enhanced by adherence to bubbles. Moreover, argon bubbling can create turbulent eddy flow from bath stirring, which improves inclusion agglomeration.[5–7] Therefore, the agglomeration behavior of nonmetallic inclusions at the steel/Ar interface needs to be well understood and controlled. While the authors are aware that there are a number of mechanisms that are important in the agglomeration of inclusions,[8–14] the focus of the current work is entirely aimed at the agglomeration of inclusions at metal/gas interfaces. This is relevant to interaction between inclusions and bubbles, is necessary to understand observed inclusion behavior in the confocal laser scanning microscopy (CLSM), and has the potential to offer important insights into inclusion agglomeration at the slag/metal interface. The collision and agglomeration of inclusions has been investigated experimentally by using high-temperature CLSM. The agglomeration of Al2O3,[8,14] 80 pct Al2O3Æ20 pct SiO2,[8] CaOÆAl2O3 with different ratios of Ca/Al,[9] MgO,[10] 93 pct Al2O3Æ7 pct MgO,[10] complex Al2O3ÆCaOÆMgO and Al2O3ÆCaOÆSiO2,[11] Al2O3Æ Ce2O3,[12] MgAl2O4,[14,15] and liquid inclusions[11,14] at the steel/Ar interface has been reported. Besides the
experimental works, Nakajima and co-workers[10,11] pioneered the application of the Kralchevsky–Paunov model[16,17] to process metallurgy, calculating the capillary force for inclusion agglomeration at the steel/Ar interface. However, the inclusions in their calculations are only defined as solid particle, liquid particle, and complex particle. The quantitative analysis for inclusions with different chemical compositions has not been made. In this work, the attractive forces between agglomerating Al2O3 inclusions with various sizes were measured in situ by CLSM; thereafter, the experimental results were compared with the calculations by the revised Kralchevsky–Paunov model. The effect of inclusion size on attractive capillary force was invest
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