AbstractAn important measure in steel processing industry is achieving the required mechanical properties and micro structure of the material. A new phenomenon has been discovered recently which allows to refine ferrite grain significantly and to spheroidise carbides over a very short time compared to conventional heat treatment techniques. The newly developed technology based on the ASR (Accelerated Spheroidisation and Refinement) effect consists in heating a steel workpiece through thickness to a temperature no higher than Ac1 and in subsequent plastic deformation. The energy introduced through plastic deformation causes the workpiece temperature to increase. This temperature increase, however, is not uniform throughout the workpiece cross-section, leading to substantial inhomogeneity. Fully austenitized regions, partially austenitized regions, and areas where no phase transformation occurred, coexist. In locations previously subjected to intensive plastic deformation, cementite lamellae disintegrate and globular carbides form. In regions subjected to milder plastic deformation, spheroidisation does not occur directly in the course of the thermomechanical treatment. Despite, the cementite lamellae show a stronger tendency to spheroidise during subsequent annealing. The combination of a suitable pre-heating temperature, an appropriate amount of strain and a possible reheating leads to transformation of initial ferrite-pearlite micro structure with lamellar pearlite into desired ferrite matrix with spheroidised carbides. Key microstructure parameters governing the properties of ferrite-pearlite steels include exactly the ferrite grain size, the distribution of defects within the ferrite grain and the distribution and morphology of carbides. The present article describes a new thermomechanical treatment technique which allows controlling these microstructure parameters and related mechanical properties in order to achieve their favourable combination in structural carbon steel C45. The processing time is very short when compared to several-hour conventional heat treatments. This offers potential for achieving desired mechanical properties with time and energy savings.