Abstract
Varying contents of carbon, titanium and boron were used in the base steel composition of 0.30 wt% Si, 2.0 wt% Mn, 0.006 wt% S, 0.03 wt% Nb, and 30–35 ppm N. Hot ductility tests were performed with Gleeble-3800, after the steel sample was in-situ melted, solidified, and cooled to the test temperature. Investigation was completed with thermodynamic and kinetic simulations. The best results were obtained for steels containing 58–100 ppm B and 35 ppm Ti. They showed very good hot ductility of 80–50% RA within the temperature range between 1250 °C and 800 °C. It was shown that titanium and boron were effective in improving the hot ductility. Titanium protected boron from binding into BN and was low enough to prevent excessive (Ti,Nb) carbonitride precipitation, which both could decrease hot ductility. Boron that precipitated along austenite grain boundaries as iron boride Fe2B was very beneficial for the hot ductility of steel.
Funder
Research Fund for Coal and Steel