TH48812B - High-strength cold-rolled steel sheet and how it is manufactured - Google Patents

Abstract

DC60 (09/03/48) This invention involves high strength cold rolled steel sheet. Containing 0 .015% or less of carbon, 1.5% or less of silicon, 0.4 to 3% of manganese, 0.15% or less of phosphorus, 0.02% Or less of sulfur, 0.1 to 1% of sol. Aluminum, 0.1% or less of nitrogen, 0.2% or less of titanium, by mass percentage. And the remainder is iron, and the indispensable impurity in this steel plate 1 is less than or equal to ([Ti] / 48) / ([C] / 12 + [N] / 14) formed where [M] represents the amount of element M because of the property Superior formability and TS of 340 to 590 MPa, Nian steel plate. The high strength cold roll of this invention is ideal to be used for automotive parts that are difficult to extruded, such as exterior panels, side panels and door panels. The invention involved cold rolled steel sheets of high strength. Containing 0 .015% or less of carbon, 1.5% or less of silicon, 0.4 to 3% of manganese, 0.15% or less of phosphorus, 0. 02% or less of sulfur, 0.1 to 1% of sol. Aluminum, 0.1% or less of nitrogen, 0.2% or less of titanium, by The mass percentage and the remainder are iron and impurities that cannot be The Liang League. In this steel plate, 1 is less than or equal to ([Ti] / 48) / ([C] / 12 + [N] / 14), where [M] represents the amount of element M. due to its properties in Superior formability and TS of 340 to 590 MPa, Nian steel plate. The high strength cold roll of this fabrication is suitable to be used This applies to automotive parts that are difficult to extruded, such as the side panels and the panels inside the door.

Claims (3)

High strength cold rolled mild steel sheet containing 0.015% or less of carbon, 1.5% or less of silicon, 0.4 to 3% of manganese, 0.15% or less of phosphorus, 0.02% or less of sulfur, 0.1 to 1% of sulfate, aluminum, 0.01% or less of nitrogen, 0.2% or less of titanium. wherein the mass percentage is less than or equal to ([Ti] / 48) / ([C] / 12 + [N] / 14) ....................(1) wherein [M] represents the amount (mass percent) of element M. 2. High strength cold rolled steel sheet of claim 1, wherein the amount of sol. aluminum is 0. 2 to 0. 7%. 3. High strength cold rolled steel sheet of claim 1, wherein the equation (2) that follows occurs 0. 3 is less than or equal to [Si] + 10 X [P] is less than or equal to 1.4 .....................(2) wherein [M] represents the amount (mass percent) of element M. 4. High strength cold rolled steel sheet of claim 2, wherein the equation (2) that follows occurs 0 . 3 less than or equal to [Si] + 10 X [P] less than or equal to 1.4 ..................... (2) wherein [M] represents the amount (mass percent) of element M 5. The high strength cold rolled steel sheet of claim 1. further comprises, by mass percent, 0 . 002 to 0 . 02% of niobium, wherein the following equation (3) occurs 1 is less than or equal to ( [Nb] / 93 + [Ti] / 48) / ( [C] / 12 + [N] / 14) ....................... (3) wherein [M] represents the amount (mass percent) of element M 6. The high strength cold rolled steel sheet of claim 4. further comprises, by mass percent, 0 . 002 to 0 . 02% of niobium, wherein the following equation (3) occurs 1 is less than or equal to ( [Nb] / 93 + [Ti] / 48) / ( [C] / 12 + [N] / 14) ....................... (3) wherein [M] represents the amount (mass percent) of element M. 7. The high strength cold rolled steel sheet of claim 1. further comprises, by mass percent, 0. 0001 to 0. 003% of boron. 8. The high strength cold rolled steel sheet of claim 6. further comprises, by mass percent, 0. 0001 to 0. 003% of boron. 9. The high strength cold rolled steel sheet of claim 1. further comprises, by mass percent, at least one element selected from A group consisting of 0.03 to 0.5% of copper, 0.03 to 0.5% of nickel, 0.03 to 0.5% of chromium, 0.05 to 0.3% of molybdenum, and 0.005 to 0.5% of vanadium. 1 0. The high strength cold rolled mild steel sheet of claim 8 further comprises, by mass percent, at least the following elements: Out of the group consisting of 0. 03 to 0. 5% of copper, 0. 03 to 0. 5% of nickel, 0. 03 to 0. 5% of chromium, 0. 05 to 0. 3% of molybdenum, and 0. 005 to 0. 5% of vanadium 1 1. High strength cold rolled mild steel sheet according to claim 1. also comprising, by mass percent, at least one element selected from the group consisting of 0.002 to 0.2% of antimony and 0.002 to 0.2% of tin, for which the following equation ( 4 ) occurs: 0.002 less than or equal to [Sb] + [Sn] / 2 less than or equal to 0.2 ...................... (4) where [M] represents the amount (mass percent) of element M 1 2. The high strength cold rolled mild steel sheet of claim 10, further comprising, by mass percent, at least one element selected from the group consisting of 0.002 to 0.2% of antimony and 0.002 to 0.2% of tin, wherein the following equation (4) occurs: 0.002 less than or equal to [Sb] + [Sn] / 2 less than or equal to 0.2 ...................... (4) wherein [M] represents the amount (mass percent) of element M 1 3. A method for producing high-strength cold rolled mild steel sheets, comprising the steps of burning the slabs having the chemical composition according to one of claims 1. to 12 at a temperature of 1,080 to 1,350°C; hot rolling the burnt slabs at a finishing temperature between (Ar3 - 20)°C and (Ar3 + 150)°C to form the hot rolled mild steel sheets; coiling the hot mild steel sheets at a coiling temperature CT in accordance with equations (5) or (6) as follows; rolling the hot rolled mild steel sheets by intercepting a layer of 50 to 90% to form the cold rolled mild steel sheets; and continuously annealing the cold rolled mild steel sheets at a temperature of 750 to 850°C or closed annealing the cold rolled mild steel sheets at a temperature of 600 to 750°C; 480 less than or equal to CT less than or equal to 580 + 0 . 17 / { ( [Ti] + 0.08 X [sol . .Al ] ) X [P] }. . . . (5) , and 480 less than or equal to CT less than or equal to 580 + 0.17 / { ( 0 . 6 X [Nb] + [Ti] + 0 . 0 8 X [ Sol..Al ] X [P] } . . . . . . . . ( 6 ) , where [M] represents the amount (mass percent) of element M.