TH35747B - High-strength cold-rolled steel sheets and methods for manufacturing steel plates. - Google Patents

Abstract

DC60 This invention involves cold-rolled steel with low C-Nb that provides tensile strength 340 to 440 MPa, for example cold rolled steel, which is essentially C 0.0040. To 0.01% Si Not more than 0.05% Mn 0.1 to 1.0% P 0.01 to 0.05% S not more than 0.02% sol.Al 0.01 to 0.1% N not more than 0.004% Nb 0.01 to 0.14% by wt. Fe and impurities are inevitable. And which n is not greater than 0.21, which has been calculated From two points of the specified stress (1% and 10%) that were observed in the tensile test. Same style And involves methods for the production of cold-rolled steel. This invention will organize Prepared high-strength cold-rolled steel for automotive exterior powder with the ability to Make a wonderful composite image Resistance to brittleness during the second operation. Formability at the welded part Anti-burr ability, good surface appearance and material consistency in the roll. The invention involves cold rolled steel with low C-Nb that provides a tensile strength of 340 to 440 MPa, for example cold rolled steel, which essentially contains C 0.0040 to 0.01% Si Not more than 0.05% Mn 0.1 to 1.0% P 0.01 to 0.05% S Not more than 0.02% sol.Al 0.01 to 0.1% N not more than 0.004% Nb 0.01 to 0.14% wt. And impurities that are inevitable And which n is not greater than 0.21, which has been calculated From two points of the specified stress (1% and 10%) that were observed in the tensile test. Same style And involves methods for the production of cold-rolled steel. This invention will organize Prepared high-strength cold-rolled steel for automotive exterior powder with the ability to Make a wonderful composite image Resistance to brittleness during the second operation. Formability at the welded part Anti-burr ability, good surface appearance and material consistency in the roll.

Claims (5)

1. Cold rolled steel with high strength, it is mainly composed of C 0.0040 to 0.01%, Si 0.05% or less, Mn 0.10 to 1.0%, P 0.01 to 0.05%, S 0.02%. Or less, so l.Al 0.01 to 0.1%, N 0.004% or less, Nb 0.15% or less, and Ti 0.05% or less may be chosen, and B may be chosen 0.002% or less. By weight And, significantly, the remaining amount is Fe and inevitable impurity. And which corresponds to the formula (6): (12/93) xNb * / C (formula) 1.2 (6) where Nb * = Nb- (93/14) xN and C, N and Nb are defined as Package quantity in units % By weight of C, N and Nb, respectively, and with n values of 0.21 or more, which were calculated. From two points of stress, determined at 1% and 10% that were observed in the pull test. Same style 2. The high-intensity steel of claim 1 also contains Ti 0.05% or less by weight. 3. The high-intensity steel of Clause 1 also has B 0.002% or less by weight. 4. Methods for producing high-strength cold-rolled steel. This includes the steps of: (a) Preparation of continuous casting of steel. They are essentially C 0.0040 to 0.010%, Si 0.05% or less, Mn 0.10 to 1.0%, P 0.01 to 0.05%, S 0.02% or less, so l.Al 0.01 to 0.1%, N 0.004% or less. More than, Nb 0.15% or less by weight and significantly the remainder, Fe and impurities. And which corresponds to the formula (6): (12/93) xNb * / C (formula) 1.2 (6) where Nb * = Nb- (93/14) xN and C, N and Nb are defined as Package quantity in units % By weight of C, N and Nb respectively (b) hot-rolled steel preparation by finishing the extrusion from step (a) at the transition temperature. Ar3 or higher (c) Hot rolled coil from step (b) at temperatures from 500 ํ to 700 ํ (d), cold rolling through hot rolled steel obtained. Rolling from steps (c) and (e) annealing of steel from steps (d). 5. The high-intensity steel of Clause 2 also has B 0.002% or less by weight.