Influence of hot plastic deformation on properties of the carbon steel

Abstract

Purpose. Determination of the influence of hot plastic deformation degree on the set of carbon steel properties. Methodology. Steel with 0.6 % carbon was used for the study. The steel structure corresponded to the state after compression at 1,240 °C. Mechanical properties were determined by the tensile curve, friction stress of the ferrite crystal lattice and resistance of interphase boundary pearlite to propagation of deformation were estimated. Findings. Depending on the structural state of austenite, dispersion of pearlite colonies is accompanied by different rates of change in the properties of carbon steel. For pearlite formed from austenite after annealing, the strain hardening coefficient and maximum ductility are inversely proportional. For pearlite formed from austenite with preserved substructure after hot deformation, the strain hardening coefficient and maximum ductility are related through the proportional relationship. Originality. Preservation of the substructure of hot-deformed austenite affects propagation deformation in pearlite of the steel. Against the background of decreasing friction stress of the ferrite crystal lattice, there is an increase in resistance of ferrite-cementite boundary of the pearlite to the spread of deformation. Practical value. For carbon steels with a pearlite structures, the accelerated increase in ductility from maintaining the proportion of hot work hardening of the austenite will improve technology for manufacturing rolled products of large sections. When producing thermally strengthened rolled products, achieving a simultaneous increase in strength and plastic properties is ensured by increasing ability of metal to strain hardening.