Influence of centerline segregation on the crystallographic features and mechanical properties of a high-strength low-alloy steel

Abstract Two regions with different degrees of centerline segregation in a bainitic steel were studied to explore the influence of segregation on hardenability and mechanical properties. With increased severity of segregation, the microstructure at centerline regions changed from lath bainite to martensite, associated with a deterioration of toughness, the mechanism of which was investigated from the perspective of crystallographic features. The high-level local enrichment of alloying elements led to a large packet and Bain zone size and strong variant selection, which were unfavorable for crack deflection and transformation strain accommodation. As a result, the toughness of severely segregated regions was decreased.