Study of the relationship between stacking fault energy and microstructure in different compositions of Fe-Mn steels produced by weld deposit

Abstract

The properties of high manganese steels are usually related to the mechanism of austenite deformation, either martensite or twin formation during deformation. This deformation mechanism is often related to the stacking fault energy (SFE) that the material possesses. Studies show that SFE values between 0 and 8 mJ/m² provide formation of ε martensite during deformation, whereas only twins are formed for energies above 18 mJ/m². Intermediate values provide the formation of both ε martensite and twins. In this way, it is possible to predict the microstructure and, consequently, mechanical properties with the knowledge of the material's SFE. In this work, a weld consumable with high manganese content was deposited on a SAE 1012 carbon steel plate with the flux-cored arc welding process producing different chemical compositions and consequently different SFE that varied as a function of the dilution. Low dilution conditions led to austenite and ε martensite formation in the molten zone, while in high dilution conditions, α' martensite were found,besides those other two. Manganese was found to be the most influential element in the phase formation change, based on SFE and SFE components analysis.