Schaeffler diagram for high Mn steels

The microstructures of 50 high Mn steels, which were annealed at approximately 1000 °C and then water quenched, were predicted using the original Schaeffler diagram, the modified Schaeffler diagram with shifted phase boundaries, and equations for Cr and Ni equivalents. Although the modified Schaeffler diagram showed better microstructural predictions compared with the original Schaeffler diagram, it still had a lack of accuracy in microstructural prediction, particularly single austenite, austenite + ferrite, and austenite + ferrite + martensite microstructures. However, the adjustment of the Al coefficient for the Cr equivalent greatly improved the accuracy of microstructural prediction. As a result, the modified Schaeffler diagram, which was plotted with the Cr equivalent, calculated with a new coefficient of Al (3.5), exhibited the best prediction of the microstructures of high Mn steels, except for a few alloys with ε-martensite.