Abstract
Loss of hot ductility at the straightening stage of the continuous casting of high-strength low-alloy steel is attributed to different microalloying elements, in particular, Nb. However, such elements are essential for the desired mechanical characteristics of the final product. Since the chemistry cannot be altered to alleviate the problem, thermomechanical processing was studied in order to improve the hot ductility. Two Nb-microalloyed steels, one also containing B, were examined. The thermal history occurring in the continuous casting process was taken into account as well. First, it was noticed that the steel with B has a higher hot ductility than the other after being subjected to in-situ melting followed by the thermal schedule. Grain boundary sliding was recognized as the failure mechanism. Then, the effect of deformation applied in the vicinity of the δ→γ transformation, while the thermal schedule was being executed, was investigated. Such deformation appeared to improve the hot ductility remarkably. Finally, the mechanism of such improvement in the hot ductility was elaborated.
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Zarandi, F., Yue, S. Failure mode analysis and a mechanism for hot-ductility improvement in the Nb-microalloyed steel. Metall Mater Trans A 35, 3823–3832 (2004). https://doi.org/10.1007/s11661-004-0288-0
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DOI: https://doi.org/10.1007/s11661-004-0288-0