HIGH TENSILE COLD ROLLED STEEL PLATE AND METHOD FOR MANUFACTURING THE COLD ROLLED STEEL PLATE

摘要

A high-strength cold-rolled steel sheet having a tensile strength of 340 MPa or more, which can certainly prevent occurrence of galling, can be manufactured even if a large number of the steel sheets are continuously press-formed. This is because a surface texture thereof is controlled so that the surface texture includes flat areas in which a roughness profile has a deviation of ± 2 µm or less from a filtered waviness curve and a dented portion having a maximum depth between 10 µm and 50 µm from the filtered waviness curve, wherein an average area of the dented portion is more than 0.01 mm 2 and 0.2 mm 2 or less, and an area fraction of the dented portion relative to the entire surface thereof is 5% or more and less than 20%.