One of the major quality problems encountered in continuous casting is the formation of transverse cracks, which is partly due to the poor hot ductility of the cast steel. In this work, high temperature tensile testing is used to determine the hot ductility of a Nb-Ti and Ti-B microllayed steels. The influence of reheat treatment on hot ductility of the alloys is studied. In order to accomplish this task, steel specimens were reheated near the incipient melting temperature, and subsequently tensile tested to fracture at a strain rate typical of the unbending operation over a range of temperatures, in order to obtain hot ductility data. The results are compared to those obtained after melting and solidification prior to high temperature tensile testing. As well, tensile specimens were subjected to thermal histories typical of continuously cast billet surface up to the unbending operation, and then subjected to a tensile test to fracture. In other words, physical simulations of the continuous casting procedure were performed. (Abstract shortened by UMI.)

Yue, S. (Advisor)