Ferritic layers formation mechanism during oxidation of FeMnSiCrNi alloys: Effect of temperature and influence on oxidation behavior

Abstract

Ferritic layer formation occurs after oxidation in Mn-rich austenitic alloys. It has significant effects on high-temperature oxidation resistance, but a better understanding of its formation is needed to control these effects. Thus, two FeMnSiCrNi alloys were exposed to six temperatures between 675 and 800 °C for 100 h. A relationship between mass variation and ferrite thickness was revealed, as Mn and Cr depletion occurred due to the Mn2O3/MnCr2O4 formation. Thermodynamic calculated phase diagrams indicated ferrite stability at high temperatures, affecting oxidation resistance. Finally, the Mn concentration profile changes during oxidation were studied with DICTRA analyses to explain the ferritic layer growth. By describing the growth and characteristics of this layer, the study can serve as a starting point for future investigations into designing more oxidation-resistant FeMnSiCrNi alloys.

Keywords

• High-temperature oxidation
• FeMnSiCrNi alloys
• Manganese-depleted layer
• Phase transformation