The Effect of Niobium on the Changing Behavior of Non-Metallic Inclusions in Solid Alloys Deoxidized with Mn and Si during Heat Treatment at 1473 K

Abstract

Abstract:To clarify the effect of niobium (Nb) on the changing behavior of oxide inclusions in alloys containing different concentrations of Mn, Si, and Nb, heat treatment experiments at 1473 K were conducted and changes in the morphology, size, quantity, and composition of these inclusions were investigated. The stability of the oxide inclusions in both molten and solid Fe-Mn-Si-Nb alloys was also estimated by thermodynamic calculation using available data. Results showed that the change in the composition of the oxide inclusions owing to heat treatment depended on the concentrations of Nb and Si in the alloy. MnO-SiO 2 -type oxide inclusions gradually transformed into MnO-Nb 2 O 5 -type or MnO-SiO 2 -& MnO-Nb 2 O 5 -type inclusions in low-Si and high-Nb alloys after heating for 60 min. However, the shape of the inclusions did not change clearly. It was indicated that, during the heat treatment at 1473 K, an interface chemical reaction between the Fe-Mn-Si-Nb alloys and the MnO-SiO 2 -type oxide inclusions occurred according to the experimental and calculation results.

Alloy Steels

“…Many alloy steels are heat treated and understanding the effects of heat treatment and heat treating parameter selection ensure the correct microstructure and properties are attained. Readers will find these topics addressed by several authors in our pages [10,[15][16][17][18]. Those readers interested in improving the corrosion resistance of alloy steels will find several pieces on this topic [2,19,20].…”