Influence of Annealing on Delamination Toughening of Mo-Bearing Medium-Carbon Steel with Ultrafine Elongated Grain Structure Processed by Warm Tempforming

Ultrafine elongated grain (UFEG) structure with a strong <110>//rolling direction fiber texture was created for 0.4%C-2%Si-1%Cr-1%Mo steel (mass%) through deformation of tempered martensite using multi-pass caliber rolling at 773 K reduction 78% (i.e. warm tempforming). Annealing the tempformed 843 enhanced delamination toughening lower temperatures without significant loss tensile strength 1.8 GPa. It suggested that controlled precipitation nanoscale Mo-rich precipitates in UFEG structure.