Effect of Direct Cooling Conditions on Characteristics of Drop Forged Ti+V+B Microalloy Steel

Hot deformation and controlled direct cooling of medium carbon HSLA steel 35MnB4 modified with Ti and V is presented. The study of effect of thermomechanical processing (TMP) conditions on grain refinement and precipitation kinetics was oriented at replacement of conventional with direct heat treatment by imposing the varied processing routes on as-forged non-deformed and restored grains, referring to the vital problem of within-part nonuniformity. Examination of microstructure and mechanical properties showed the effect of accelerated-air cooling on deformed and non-deformed sections and conclusions on the response of the microalloy steel to differing TMP conditions in the context of requirements towards parts operating under severe wear-loading conditions. Due to specific requirements of proper strength/ductility balance in locations, target application – a tarmac cutter base was used as a case study of the efficiency of strength/plasticity enhancement, indicating bearing effect of the straining history on microstructure-properties combination, with 700-1100 MPa divergence within direct-cooled parts.