Bake Hardenable Cold Rolled Steel Sheet With Improved Aging Property And Bake Hardenability, And Manufacturing Method Thereof

摘要

The present invention relates to a bake hardenability and anti-aging property at room temperature excellent bake hardening type cold-rolled steel sheet and a manufacturing method thereof. ; This according to the invention in weight% C: 0.0018 ~ 0.0025%, Si: 0.02% or less, Mn: 0.2 ~ 0.7%, P: 0.05 ~ 0.08%, S: 0.01% or less, acid soluble Al: 0.08 ~ 0.12%, N : 0.0020% or less, Nb: 0.005 ~ 0.011%, B: 0.0005 ~ 0.0015%, and the balance is composed of Fe and other unavoidable impurities, wherein the Nb and Al is 50- (1589 × Nb) + (62 × Al) 30 and 44- (2119 × Nb) is added so as to satisfy the formula of 30, the grain size of the microstructure is provided a baking hardening type cold-rolled steel sheet, characterized in that more than ASTM No. 9, Al- killed steel keel of the composition ( Killed steel) and then wound at a temperature ranging from after the homogenization heat treatment at more than 1200 ℃ 900 ~ and finish hot-rolled in a temperature range of 950 ℃, 600 ~ 650 ℃, then subjected to cold rolling of 76% to 80% 770 - method for producing a continuous annealing, and 1.2% to 1.5% of baking hardening type cold rolling step consisting of carrying out the temper rolling the steel sheet at a temperature range of 830 ℃ is provided. ; By this baking curing high strength cold rolled steel sheet can be achieved, lightweight materials of the bodywork of the car. ; Bake hardened steel, anti-aging, bake hardenability, grain, steel sheets for automobiles