HIGH-STRENGTH HOT-ROLLED STEEL SHEET EXCELLENT IN CHEMICAL TREATABILITY

摘要

Disclosed is a high-strength hot-rolled steel sheet excellent in chemical treatability, wherein the maximum height (Ry) of profile irregularities in the surface is not less than 10 µm and the mean spacing (Sm) of the profile irregularities in the surface is not more than 30 µm. This high-strength hot-rolled steel sheet satisfies either, preferably both, of the following: 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 surface is not less than 60%. This high-strength hot-rolled steel sheet stably exhibits excellent chemical treatability, even when it contains Mo which is added for enhancing the strength thereof.