Evolution of Interfacial Features of MnO-SiO2 Type Inclusions/Steel Matrix during Isothermal Heating at Low Temperatures

Abstract

To clarify the evolution of interfacial features between MnO-SiO2 type inclusions and Si-Mn killed steel during isothermal heating at low temperatures, two diffusion couple samples were investigated under heat treatment at 1173 K and 1273 K, respectively. The experimental results show that the diffusion of oxygen from the oxide to the alloy is the restrictive link of the solid-state reaction between MnO-SiO2-FeO oxide and steel matrix at low heating temperatures. With increasing heating time or temperature, more FeO in the oxide decomposed, and the resulting oxygen diffused into the alloy and reacted with Mn and Si elements. The critical heating temperature at which the interfacial reaction can occur was determined to be 1173 K. And a dynamic model that predicts the change in the width of the particles precipitation zone at low temperatures was also established based on Wagner equation.

Keywords

• interfacial reaction
• isothermal heating
• low temperatures
• oxide inclusions