Assessment of Si–O Equilibria and Nonmetallic Inclusion Characteristics in High Silicon Steels

Abstract

Si–O deoxidation equilibria in liquid steel are not reliably known, especially in the high silicon concentration range. Herein, Si–O deoxidation equilibria in liquid steel at 1823–1873 K have been investigated for a wide range of silicon concentrations. Thermodynamic analysis was carried out using Wagner's interaction parameter formalism (WIPF) and FactSage 8.1. The first and second‐order cross‐interaction parameters estimated at 1873 K are as follows: , , . Moreover, nonmetallic inclusion characteristics were also investigated for varying silicon concentrations.

Influence of Ferrosilicon Addition on Silicon-oxygen Equilibria in High-silicon Steels

“…The sample was then furnace-cooled. The sampling methodology and characterization of solidified ingot were similar to our previous study 8) . The solidified ingot after each equilibrium experiment was used as a sample which was sectioned for various analyses, for example, the sampling locations for (i) compositional analysis was the central bottom (CB) region and (ii) inclusion analysis has been carried out in the central middle (CM) and CB regions of the solidified ingot.…”

“…High-purity electrolytic iron (99.99%) and FeSi were commercially procured. The details of the experimental setup and method for carrying out the experiments in the vertical tube furnace under a purified argon atmosphere have been reported in our previous study 8) . A schematic of the experimental setup is shown in Fig.…”

“…Si-O equilibria in liquid iron/steel has been investigated using equilibrium experiments and thermodynamic analysis in the past several decades [2][3][4][5][6][7][8][9] as summarized in Table 1. Vacuum 3,4,6,10,11) or inert gas 7,8) combustion methods have been used to measure the total oxygen (TO) content. The inert gas combustion method has been most extensively used in recent decades for fast, easy, and accurate analysis 8,12) .…”

“…Vacuum 3,4,6,10,11) or inert gas 7,8) combustion methods have been used to measure the total oxygen (TO) content. The inert gas combustion method has been most extensively used in recent decades for fast, easy, and accurate analysis 8,12) . Our recent study 8) established Si-O equilibria using high-purity silicon (HPS) in liquid iron at 1823-1873 K. The adopted sampling methodology 8) was effective to avoid/minimize the inclusions in the analysed sample for TO measurement.…”

“…In the present study, (i) a detailed investigation of the FeSi alloy for the assessment of the impurities and (ii) the influence of these FeSi impurities on the Si-O equilibria established in liquid iron/steel at 1873 K have been studied. Finally, the influence of FeSi vis-à-vis high-purity silicon (HPS) addition 8) on Si-O equilibria has been examined.…”