5th International High Manganese Steel Conference - HMNS 2022

In recent years, most of the studies on medium-Mn steels have focused on the chemical compositions, microstructural evolution, mechanical properties, and heat treatment schedules with different C and Mn contents. The micro/nano scale grain size of medium Mn steel after austenite reverse transformation (ART) provides a challenging situation to characterize the microstructure and evaluate chemical composition on bulk samples.
Here we used a combination of Electron Probe Micro-Analysis (EPMA) and Electron Back-Scattering Diffraction (EBSD) to characterize different medium Mn steels obtained via direct ART route vs. a reaustenitized quenched (RAQ) + ART route with different temperatures and soaking time.
Different routes along with different ART soaking times and temperatures ultimately affect the growth of retained austenite (RA) phase with different alloying compositions. This would further change the SFE of the RA phase affecting mechanical properties. Such characterizations are essential as chemistry differences and morphological differences provide a key understanding to the microstructure-property relationship of such steels.
A dedicated method was carefully designed to perform high-resolution quantitative carbon and manganese mappings on medium-Mn steels after ART processing materials. To enable direct comparison between chemical and structural information of the analysed regions, EPMA and EBSD measurements were performed at the same location. Highly sensitive and spatially resolved experiments provided a direct understanding to the achieved mechanical property based on the composition and morphology of sub-micrometer sized globular (“blocky”) and acicular (“film-like”) RA domains.