| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To provide a hot-rolled steel plate which has high-strength and excellent pitting-corrosion resistance, can be manufactured inexpensively, and accordingly is most suitable for being used particularly as a raw material of such a structural member of automobiles as to be represented by a chassis, a bumper and an undercarriage component. <P>SOLUTION: The hot-rolled steel plate which has a steel composition comprising, 0.01-0.35% C, 0.01-2.0% Si, 0.1-3.0% Mn, 0.3% or less P, 0.01% or less S, 0.005-2.0% Al, 0.01% or less N, 0.01-0.25% Ti and the balance Fe with impurities; and contains 50 pieces/mm<SP>2</SP>or less by number density in total of inclusions, crystallized products and precipitates having particle sizes of 5μm or larger, in a cross section in a sheet thickness direction of a surface layer part of the steel plate between the surface of the steel plate and a position of 50μm deep in a sheet thickness direction. <P>COPYRIGHT: (C)2010,JPO&INPIT</p> |
