Hot Ductility of High-Mn Steel with Niobium and Titanium

The work presents the results of research on the effect of deformation parameters on hot ductility of high-Mn aus - tenitic steel with niobium and titanium. The investigations were carried out on steel with 0.05% C, 24% Mn, 3.5% Si, 1.5% Al, 0.030% Nb and 0.075% Ti. Hot static tensile test was performed using Gleeble 3800 thermomechanical simulator. Samples were deformed in a temperature range from 1050 °C to 1200 °C with a strain rate of 3·10 -3 s -1 . The reduction in area (RA), determined in the static tensile test, was the basis for determining the hot ductility of the examined steel. Reduction in area of examined steel decreases from 88% at the temperature of 1050 °C to 59% at 1200 °C. High hot ductility of the investigated steel is the result of the synergy of chemical composition optimization, properly conducted modification of non-metallic inclusions and formed fine-grained microstructure of dynamically recrystallized austenite. In addition to hot ductility, parameters characterizing susceptibility of studied steel to high temperature cracking were also defined, namely: ductility recovery temperature (DRT), nil ductility temperature (NDT) and nil strength temperature (NST) were determined. The values of these temperatures are 1240 °C, 1250 °C and 1270 °C, respectively. This means that the temperature of the beginning of plastic deformation of ingots of this steel may be equal even slightly above 1200 °C. In addition, the high-temperature brittleness range (HTBR) was determined, which is equal 30 °C.