Study on the Interfacial Reactions between an Fe–Mn–Si Alloy and Complex Oxides Containing FeO during Isothermal Heating

Chengsong Liu,Hua Zhang,Xiaoqin Liu,Bao Wang,Fei Ye

doi:10.3390/met8040251

Abstract

To precisely control the characteristics of complex oxides by heat treatment, the effect of FeO on the interfacial reactions that occur between an Fe–Mn–Si alloy and CaO–SiO2–Al2O3–MgO–MnO–FeO oxide was studied and clarified. Eight types of diffusion couples with different compositions of oxides were produced using a confocal scanning laser microscope (CSLM). The morphologies of the alloy–oxide interfaces and the changes in their chemical compositions with isothermal heating at 1273 and 1473 K for 10 h were investigated. A modified dynamic calculation model was established and verified to achieve better understanding on the interfacial reaction mechanism between the Fe–Mn–Si alloy and the multicomponent oxide with different FeO content during isothermal heating. The results showed that during isothermal heating at 1273 and 1473 K, “solid–solid” and “solid–liquid” alloy–oxide reactions occurred in the A-1-x and A-2-x diffusion couples, respectively. The interfacial alloy–oxide reactions were enhanced by increasing the initial FeO content in the oxide and the heating temperature. The particle precipitation zone (PPZ), Mn-depleted zone (MDZ) and Si-depleted zone (SDZ) widths in the A-1-x and A-2-x diffusion couples after heating also showed a positive correlation with the increase in the initial FeO content in the oxide, as well as the size and number of MnO·SiO2 inclusions. The diffused oxygen from the oxide reacting with elemental Mn and Si in the alloy plays a dominant role in the A-1-x diffusion couple during heating, whereas for A-2-x, the dominant reaction is between elemental Si in the alloy and MnO in the oxide.

Highlights

To obtain super-clean steel products with high mechanical properties, such as fatigue resistance, tensile strength, and impact toughness, various compound deoxidizers with high efficiencies are used to reduce the dissolved oxygen and modify the non-metallic inclusions in molten steel [1,2]
The diffused oxygen from the oxide reacting with elemental Mn and Si in the alloy plays a dominant role in the A-1-x diffusion couple during heating, whereas for A-2-x, the dominant reaction is between elemental Si in the alloy and MnO in the oxide
The effect of FeO on the interfacial reactions that occur between an Fe–Mn–Si alloy and

Summary

Introduction

To obtain super-clean steel products with high mechanical properties, such as fatigue resistance, tensile strength, and impact toughness, various compound deoxidizers with high efficiencies are used to reduce the dissolved oxygen and modify the non-metallic inclusions in molten steel [1,2]. Evidence indicates that the characteristics of the final inclusions in steel products after hot rolling and heat treatment are often different from those of the initial ones in molten steel. Fe–Cr–Mn–Si steel in which the stable oxide changed from MnO–SiO2 to MnO–Cr2 O3 after heat treatment at 1473 K for 60 min was approximately 0.1 mass percent (pct) for 10 mass pct Cr steel and Metals 2018, 8, 251; doi:10.3390/met8040251 www.mdpi.com/journal/metals. Fine oxide particles and metal particles precipitated near the interface in the alloy and in the bulk oxide, respectively

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Conclusion