Patent ID: 8220525

Claim:
A method of making a hot rolled steel sheet, the method comprising: measuring an amount of each of copper (Cu), tin (Sn), antimony (Sb) and nickel (Ni) contained in at least a portion of molten steel; computing a copper equivalent value (Cu eq.) using the measured amount of each of Cu, Sn, Sb and Ni; providing a thickness value for a hot rolled steel sheet to be produced; estimating, using the copper equivalent value and a thickness value, the surface crack generation rate of the hot rolled steel sheet to be produced; determining if the estimated surface crack generation rate is equal to or smaller than a predetermined value; casting the molten steel into a slab; and hot rolling the slab into the hot rolled steel sheet having a thickness of about the thickness value, when determined that the estimated surface crack generation rate is equal to or smaller than the predetermined value.