COLD-ROLLED STEEL SHEET HAVING EXCELLENT BENDABILITY AND HOLE EXPANDABILITY AND METHOD FOR MANUFACTURING SAME
개요
발명자
Chang-Hyo SEO; Yeon-Sang AHN
IPC 분류
CPC 분류
Provided is a method of manufacturing a cold-rolled steel sheet. The method includes: hot-rolling a steel slab under a finish rolling outlet temperature condition of Ar3 to Ar3+50° C. after reheating the steel slab; coiling the hot-rolled steel sheet at a temperature of 600° C. to 750° C.; by cold-rolling the hot-rolled steel sheet at a reduction rate of 40% to 70%; and overaging the cold-rolled steel sheet after continuous annealing, primary cooling at a cooling rate of 1 to 10° C./sec to 650° C. to 700° C., and secondary cooling at a cooling rate of 5 to 20° C./sec to a temperature of Ms−100° C. to Ms° C. The steel slab includes, by wt %, 0.03 to 0.07 of carbon, 2.0 to 3.0 of manganese, 0.01 to 0.10 of soluble aluminum, 0.3 to 1.2 of chromium, 0.03 to 0.08 of titanium, 0.01 to 0.05 of niobium, 0.0010 to 0.0050 of boron, 0.001 to 0.10 of phosphorous.
원문 (중국어)
Provided is a method of manufacturing a cold-rolled steel sheet. The method includes: hot-rolling a steel slab under a finish rolling outlet temperature condition of Ar3 to Ar3+50° C. after reheating the steel slab; coiling the hot-rolled steel sheet at a temperature of 600° C. to 750° C.; by cold-rolling the hot-rolled steel sheet at a reduction rate of 40% to 70%; and overaging the cold-rolled steel sheet after continuous annealing, primary cooling at a cooling rate of 1 to 10° C./sec to 650° C. to 700° C., and secondary cooling at a cooling rate of 5 to 20° C./sec to a temperature of Ms−100° C. to Ms° C. The steel slab includes, by wt %, 0.03 to 0.07 of carbon, 2.0 to 3.0 of manganese, 0.01 to 0.10 of soluble aluminum, 0.3 to 1.2 of chromium, 0.03 to 0.08 of titanium, 0.01 to 0.05 of niobium, 0.0010 to 0.0050 of boron, 0.001 to 0.10 of phosphorous.