| 摘要 |
PROBLEM TO BE SOLVED: To provide a method for manufacturing a steel billet by which, even in the case where an as-continuously-cast billet is heated in the state in a process/equipment requiring rapid heating, a steel billet reduced in thermal stress cracking sensitivity and free from cracking even when heated rapidly can be manufactured and thermal stress cracking can be easily prevented at a low cost. SOLUTION: In this manufacturing method, when temporarily cooling a continuously cast billet down to room temperature and then heating and hot rolling it into a steel billet, the respective contents (mass%) of Cr and Mo in molten steel to be continuously cast are made to satisfy 0.5≤Cr+5Mo≤3.0 and also the relation between the maximum temperature differenceΔT(°C) of the internal and the external temperature of the cast billet to be heated and the above Cr and Mo contents is made to satisfy 270(Cr+5Mo)-ΔT>250 or 250(Cr+5Mo)+ΔT<700. COPYRIGHT: (C)2006,JPO&NCIPI
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