ANALYSIS OF METHODOLOGY FOR DETERMINATION OF THE FLOW STRESS IN HOT TORSION TEST

In the paper is performed a comparison of methodology for determination of the flow stress based on results of plastometric hot torsion test. As basis for calculations were taken the registered values of torque moment in the function of a number of torsions obtained during torsion test of tool steel. The torsion tests were executed at torsion plastometer in the Department of Mechanics and Plastic Working Technology at Silesian Technical University in Katowice, in the range of temperatures 850 – 1050 °C and twist rate 10 – 500 rpm. There were demonstrated significant differences in the course of stress – strain curves, and in particular the determination of flow stress maximum point.