Thermodynamic study on solubility of nitrogen in Fe-Mn-Al alloy melts

Abstract

High manganese-aluminum steel have obtained great attention because of their excellent strength, ductility and formability. However, a high manganese content can increase the solubility of nitrogen significantly and result in the formation of the AlN inclusions during the process of steelmaking. Therefore, a better understanding and control of nitrogen content and AlN inclusions in Fe-Mn-Al melts is essential for the process of steelmaking. In this work, the nitrogen solubility in Fe-Mn-Al melts ([%Mn]<20, [%Al]<2) was measured at 1 873 K under the nitrogen partial pressure range of 0.1 atm to 0.4 atm. It was concluded from the experimental results that nitrogen solubility decreased with the increase of aluminum content, but increased with the increase of manganese content. Moreover, AlN inclusions were found in the samples with the aluminum content of 1.3 mass% and 1.4 mass% under the nitrogen partial pressure of 0.4 atm. It was also confirmed that the interaction parameters of thermodynamic model for Fe-Mn-Al-N system determined by Paek et al. were effective over a wide range of aluminum content and nitrogen partial pressure.