STEEL SHEET HAVING EXCELLENT IMAGE SHARPNESS AND WORKABILITY AND ITS MANUFACTURE

摘要

PURPOSE:To manufacture steel sheets having excellent image sharpness and workability by transferring an irregularity with a specific flatness ratio onto the surface of steel sheets by use of a roll whose surface has the irregularity with the specific flatness ratio. CONSTITUTION:An irregularity is formed on the surface of a roll by a shotblast method, etc. The irregularity is such that a flatness ratio F'[A'/A(A'+B')] denoted by the area A' of comparatively flat parts whose max. peak-to-valley height Rmax is lower than 7.0mum and the area B of other parts is shown by 0.50<=F'<=0.90. The irregularity is transferred onto the surface of a steel sheet by use of a roll with the above irregularity. An obtained irregularity is such that a flatness ratio F[A/(A+B)] denoted by the area A of comparatively flat parts whose max. projection height Rmax is lower than 3.0mum and the area B of other parts is shown by 0.55<=F<=0.95. Thus, steel sheets having the excellent image sharpness and workability are manufactured.