Improved microstructural homogeneity and mechanical property of medium manganese steel with Mn segregation banding by alternating lath matrix

The influence of Mn segregation banding on the microstructure homogeneity and mechanical property of medium manganese system steels with both equiaxed and lath-like microstructures has been investigated by adding the pre-quenching treatment before the intercritical austenitization and subsequent quenching & partitioning process (IQP). Both the crack observation and KAM characterization in these two types of microstructure intuitively indicate different micro-cracking resistance and in-grain strain accommodation of intercritical ferrite during the deformation. The excessive inhomogeneous microstructure and blocky retained austenite with low stability accelerate the failure of the material with Mn segregation banding. The fine lath-like ferrites with great contact ratio to the surrounding martensites improve the microstructural homogeneity under pre-quenching process. The alternative arrangement of lath-like soft ferrite and hard martensite results in optimal mechanical properties of material with Mn segregation banding.