| 摘要 |
PROBLEM TO BE SOLVED: To provide a high-strength hot-rolled steel sheet which stably exhibits excellent chemical convertibility, even when it contains Mo which is added for enhancing the strength thereof. SOLUTION: The high-strength hot-rolled steel sheet having improved chemical convertibility satisfies the surface characteristics that the maximum height (Ry) of profile irregularities in the surface is not less than 10μm and the mean spacing (Sm) of the profile irregularities is not more than 30μm. Further, this high-strength hot-rolled steel sheet satisfies either, preferably both, of the following characteristics that the profile bearing length ratio (tp40) of the surface is not more than 20%, and the difference between the profile bearing length ratio (tp60) and the profile bearing length ratio (tp40) of the surfaces is not less than 60%. COPYRIGHT: (C)2008,JPO&INPIT
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