Influence of Ti on the Hot Ductility of High-manganese Austenitic Steels

The influence of Ti addition (similar to 0.10 wt%) on hot ductility of as-cast high-manganese austenitic steels has been examined over the temperature range 650-1,250 degrees C under a constant strain rate of 10(-3) s(-1) using Gleeble3500 thermal simulation testing machine. The fracture surfaces and particles precipitated at different tensile temperatures were characterized by means of scanning electron microscope and X-ray energy dispersive spectrometry (SEM-EDS). Hot ductility as a function of reduction curves shows that adding 0.10 wt% Ti made the ductility worse in the almost entire range of testing temperatures. The phases' equilibrium diagrams of precipitates in Ti-bearing high-Mn austenitic steel were calculated by the Thermo-Calc software. The calculation result shows that 0.1 wt% Ti addition would cause Ti(C, N) precipitated at 1,499 degrees C, which is higher than the liquidus temperature of high-Mn austenitic steel. It indicated that Ti(C, N) particles start forming in the liquid high-Mn austenitic steel. The SEM-EDS results show that Ti(C, N) and TiC particles could be found along the austenite grain boundaries or at triple junction, and they would accelerate the extension of the cracks along the grain boundaries.