Study on the Formation Mechanism of Banded Structure and Inheritance of Alloy Element Segregation in 55SiCr Steel

This study investigates 55SiCr steel using multiscale characterization techniques including, optical microscopy (OM), scanning electron microscopy (SEM), electron probe micro analyzer (EPMA), and Vickers hardness testing, to analyze the formation mechanism of axial banded structures and their effects on microstructures and mechanical properties, while revealing the genetic mechanism of alloy element segregation. The results indicated that the banded structures in 55SiCr steel originated from the segregation of Si, Cr, and Mn elements. This segregation was inherited from dendritic segregation in the as‐cast billet, elongated into a banded morphology during rolling, and further preserved during heat treatment. The element segregation influenced material performance through a dual strengthening mechanism: the solid solution strengthening of Si, Mn, and Cr in the segregation bands, combined with the pinning effect of carbides, enhanced the hardness and strength of these regions. However, this also intensified localized stress concentration and promoted microcrack initiation along the segregation bands, leading to a significant reduction in the reduction of area. Additionally, the elemental distribution differences in the segregation bands altered the localized etching resistance, resulting in contrasting microstructural features after etching and forming axial banded structures.