HOT DUCTILITY BEHAVIOR OF Fe-0.05C-24Mn-3.5Si-1.6Al STEEL WITH Nb AND Ti MICROADDITIONS

Hot ductility tests were carried out on Fe-0.05C-24Mn-3.5Si-1.6Al high-manganese austenitic steel with Nb and Ti microadditions at a concentration of 0.029% and 0.075%, respectively. Hot tensile tests were performed using Gleeble 3800 thermomechanical simulator on specimens with a diameter of 6 mm and 116.5 mm in length. Deformation was carried out in a temperature range from 1050 °C to 1200 °C with a strain rate of 2.5 · 10^-3 s^-1 and 5.0 · 10^-3 s^-1. Hot ductility was determined on the basis on evaluation of reduction in area (RA). Higher values of stress on the work-hardening curves were observed during tension carried out at higher strain rate. An analysis of the form and course of curves obtained in the tensile test allows to state that, in the studied range of hot plastic deformation parameters, the decrease of strain hardening is caused by the process of dynamic recrystallization (DRX). The reduction in area in a temperature range from 1050 °C to 1200 °C decreases from 90% to approx. 58% for the strain rate of 2.5 · 10^-3 s^-1 and from 82% to 48% – for the strain rate of 5.0 · 10^-3 s^-1.