Variant selection of bainite on the surface of allotriomorphic ferrite in a low carbon steel

► We study orientation of bainite formed on the surface of allotriomorphic ferrite. ► About 80% allotriomorphic ferrites have K-S relationship with austenite on one side. ► Bainite nucleated on K-S related interface has the same variant with the ferrite. ► Bainite has no variant selection on non K-S related ferrite/austenite interface. ► We discuss possible mechanism for variant selection using pillbox nucleus model.