A micro-alloyed 1045 steel was commercially rolled into 54 mm diameter bars by conventional hot rolling at 1000 °C and by lower temperature thermomechanical rolling at 800 °C. The lower rolling temperature refined the ferrite-pearlite microstructure and influenced the microstructural response to rapid heating at 200 °C·s -1 , a rate that is commonly encountered during single shot induction heating for case hardening. Specimens of both materials were rapidly heated to increasing temperatures in a dilatometer to determine the A c1 and A c3 transformation temperatures. Microscopy was used to characterize the dissolution of ferrite and cementite. Continuous cooling transformation (CCT) diagrams were developed for rapid austenitizing temperatures 25 °C above the A c3 determined by dilatometry. Dilatometry and microstructure evaluation along with hardness tests showed that thermomechanical rolling reduced the austenite grain size and lowered the heating temperature needed to dissolve the ferrite. With complete austenitization at 25 °C above the A c3 there was little effect on the CCT behavior.

Numerical model of controlled cooling in production of steel hot rolled bars was developed. By numerical model of controlled cooling is possible to predict a transient temperature field, microstructure evolution and hardness of rectangular steel bars during their cooling in cooling beds. The numerical model of transient temperature field is based on control volume method. The algorithm for prediction of hardness and microstructure distribution in steel bars is based on continues cooling transformation, (CCT) diagrams and real chemical composition. The numerical model and algorithm is completed to solve problems in controlled cooling of hot rolled bars in cooling beds. The controlled cooling are performed by special placement of hot rolled bars on cooling beds. Numerical model and computer program was experimentally verified by simulation of real industrial production of low alloyed steel bars. The verification of developed numerical model was performed by comparison of simulated hardness with experimentally evaluated results.

Wire rod of steel, produced by a hot rolling process, is cooled on a conveyor by action of fans sited under it. Mechanical properties of rod depend on chemical composition of steel and cooling rate experimented by the product. A mathematical model is developed in order to predict the thermal and metallurgical evolution of the steel rod on the conveyor. Convection and radiation losses are considered and the influence of the laying head is also discussed. Simulation results are compared with experimental measures obtained by an optical pyrometer in a real industrial process. Several product diameters and fan configurations are analyzed. Conclusions about the good accuracy of the model are shown. Thanks to the short computational time that the developed tool takes to predict the temperature of the wire rod along the conveyor, the tool can be potentially used in an on-line control system for the cooling process of wire rods.