Influence of Ti and V on the hot ductility of high manganese austenitic steel

The influence of Ti (mass fraction 0.10%) and the joint additions of Ti (mass fraction 0.11%) and V (mass fraction 0.20%) on the hot ductility of as-cast high manganese austenitic steels were studied using a Gleeble-3500 thermo-mechanical simulator over a temperature range of 700 to 1200℃. Fracture surfaces and particles precipitated at different testing temperatures were investigated via scanning electron microscopy (SEM) and X-ray energy dispersive spectrometry (EDS). The hot ductility curves as a function of temperature of high-Mn austenitic steels showed that Ti addition leads to loss of ductility in almost the entire testing temperature range. Moreover, the joint additions of Ti and V do not exhibit any improvement in the hot ductility, resulting in relatively poor hot ductility behavior. The phase diagrams of precipitates in Ti-and Ti-V-bearing high-Mn austenitic steels in the temperature range of 700 to 1600℃ were calculated via Thermo-Calc commercial software. The calculation results show that Ti(C,N) in Ti-bearing highMn steel precipitates at 1499℃, which is much higher than its liquidus temperature. This illustrates that Ti(C,N) particles form in the liquid steel. SEM-EDS results show that Ti(C,N) and (Ti,V) C particles form along the austenitic grain boundaries and the triple junction. These particles retard the occurrence of dynamic recrystallization and accelerate the extension of cracks near the grain boundaries.