METHOD FOR MANUFACTURING TENSILE STRENGTH 590MPA CLASS COLD ROLLED DP STEEL WITH EXCELLENT WORKABILITY AND VARIATION OF MECHANICAL PROPERTY

• Main Authors: KANG, HEE JAE, HAN, TAE KYO
• Format: Patent
• Language: English; Korean
• Published: 23.05.2012
• Subjects: ALLOYS; CHEMISTRY; FERROUS OR NON-FERROUS ALLOYS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUSMETALS OR ALLOYS; MAKING METAL MALLEABLE BY DECARBURISATION, TEMPERING OR OTHERTREATMENTS; MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVINGMATERIAL; METALLURGY; METALLURGY OF IRON; MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; PERFORMING OPERATIONS; PUNCHING METAL; ROLLING OF METAL; TRANSPORTING; TREATMENT OF ALLOYS OR NON-FERROUS METALS

PURPOSE: A method for manufacturing high-strength hot-rolled DP steel with a tensile strength of about 590MPa and low property deviation is provided to reduce energy consumption by excluding a re-heating process from the processes of the conventional mill. CONSTITUTION: A method for manufacturing high-strength hot-rolled DP steel comprises the steps of: continuously casting steel into a thin slab(a) 30-150mm thick, roughing, heating, finish rolling, cooling, and coiling the thin slab to obtain a hot-rolled strip(b), and picking, cold rolling, continuous annealing, and cooling the hot-rolled strip. In the finish rolling step, rolling speed deviation in a single strip is controlled to 15% or less and the rolling temperature of the final rolling stand is controlled to ±20°C of a target temperature. In the cooling step, the annealed strip is continuously cooled at a cooling speed of 10-150°C/s to a temperature of 200-400°C.