| 摘要 |
PROBLEM TO BE SOLVED: To provide a hot rolled steel plate minimal in rusting, practically free from deterioration in mechanical properties due to inclusions and precipitates, capable of being put into practical use with sufficient reliability even in the case that heavy extra deep drawing having >3.0 drawing ratio in particular is applied, and free from surface defects caused by cluster-like inclusions. SOLUTION: This steel plate is composed of an extra low carbon steel having a composition which contains, by weight, 0.015-0.2% Ti, <=0.01% Al, 0.0005-0.01% B, and 0.0005-0.1%, in total, of either or both of Ca and REM and in which the contents of S and either or both of Ca and REM satisfy the relation of inequality S-5×[(32/40)Ca+(32/140)REM]<=0.0014 wt.%. Further, oxide inclusions of 1-50μm maximum size contain Ti oxide and either or both of CaO and REM oxide.
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