Influence of thermo-deformation treatment parameters on the strength of hot-rolled high-strength low-carbon steels microalloyed with titanium

High-strength microalloyed low-carbon steels attract attention due to their unequalled combination of service and technological properties and their wide application in various industries. Currently, one of directions for their development involves the use of titanium microalloying and the search for appropriate optimal parameters of thermo-deformation treatment in order to achieve the required level of mechanical properties by controlling the formation of phase precipitates. This work investigates industrial hot-rolled steels with 355 and 420 MPa steel grades by thermodynamic analysis as well as by optical and transmission electron microscopy. It is established that an increase in the temperatures of finish rolling and reeling contributes to the formation of nanoscale interphase precipitates having the greatest strengthening effect. However, when reeling temperatures exceed 600 °C, the strength of the steel decreases due to an increase in the size of both grains and precipitates.