Effects of reheat conditions on the hot ductility of Nb-Ti and Ti-B microalloyed steels

This paper focuses on the influence of reheating conditions on the hot duct ility behavior of steel. Two types of hot ductility test were performed; (i ) the conventional 'isothermal' test, in which specimens were reheated, coo led to the desired test temperature and then fractured; (ii) physical simul ation of biller continuous casting, in which the specimens were subjected t o thermal histories typical of the surface of a continuously cast biller, a nd then fractured. Two reheat conditions were used, (i) reheating to the in cipient melting temperature (IM), (ii) in-situ melting and solidification ( MS). For the isothermal ductility, compared to the IM reheated specimens, the MS reheat considerably decreased the hot ductility trough for the two steels tested (a microalloyed Nb-Ti and a microalloyed Ti-B grade). For MS specime ns, the majority of the physical simulations led to hot ductility values lo wer than that predicted from the isothermally tested specimens. The opposit e was observed for IM reheated specimens.