Avaliacao do comportamento mecanico do aco estrutural SAE 4340 atraves de ensaios isotermicos de torcao a quente = Evaluation of the mechanical behavior of structural steel SAE 4340 by isothermal hot torsion tests

To reduce operating costs and improving the mechanical properties of the material produced by hot rolling is necessary to control the microstructure and metallurgical phenomena occurring during the forming process. An experimental method capable of simulating the conditions of hot rolling is the hot torsion test, a test that is efficient and relatively inexpensive to study the processes of thermomechanical rolling. This study used samples of structural steel SAE 4340 were submitted to tests in hot torsion machine of the IFES. The samples were then heated to a temperature of 1200°C and maintained at this temperature (soaking) to complete homogenization. They were then cooled at an average rate 2°C/s until the temperature of deformation. The tests were performed with constant strain rate of 0.2s-1 and varied the temperature of deformation. The result of this study obtained stress-strain curves for different temperatures. Thus, It was possible to evaluate the effects of metallurgical phenomena occurring during hot deformation.