TH71931B - High-strength galvanized steel sheets with excellent formability and methods for the manufacture of similar ones. - Google Patents

Abstract

DC60 (23/09/54), high strength galvanized steel sheet with low thickness and excellent formability and A method for producing steel plates has been prepared. What is performed is a hot rolling process. By making steel containing a mixture containing, by mass%, C 0.08 to 0.15%, Si 0.5 to 1.5%, Mn 0.5 to 1.5%, Al 0.01 to 0.1% and N 0.005% or less. Are under hot rolling to Hot rolled steel plate formation, hot rolled steel plate acid immersion, next, without cold rolling, with continuous galvanizing path, annealing where the hot rolled steel sheet is maintained. In the district Temperature one of the Ac1 transformation point reaches the Ac3 transformation point for 5 to 400 s, cooling where Cooling from the first temperature range until 700 degrees Celsius It was performed at an average cooling rate of 5 ° C / s. Or higher, and the time remains in the second temperature range at 700 ° C up to the temperature for Entering the sink for galvanizing ranges from 15 to 400 seconds and galvanizing the next order. The result is It is possible to obtain a microstructure containing ferrite phase with Fractions by area in the range 75 to 90% relative to all microstructures. And the second cycle Containing perlite, where fraction by area ranges from 10 to 25%, and therefore, plated steel plate High strength zinc with excellent formability with high strength, that is, tensile strength TS 540 Mpa or higher. And the excellent flat-stretch flange processing conditions can be achieved with 70% or more perlite. In the fractional side by the area relative to the phase cycle All second And the mean grain size of perlite was 5 micrometers or less. High strength galvanized steel sheet, which is low in thickness and has excellent formability and A method for producing steel plates has been prepared. What is performed is a hot rolling process. By making steel containing a mixture containing, by mass%, C 0.08 to 0.15%, Si 0.5 to 1.5%, Mn 0.5 to 1.5%, Al 0.01 to 0.1% and N 0.005% or less. Are under hot rolling to Hot rolled steel plate formation, hot rolled steel plate acid immersion, next, without cold rolling, with continuous galvanizing path, annealing where the hot rolled steel sheet is maintained. In the district Temperature one of the Ac1 transformation point reaches the Ac3 transformation point for 5 to 400 s, the cooling which Cooling from the first temperature range up to 700 ํ was performed at an average cooling rate of 5 ํ / sec or higher, and the time remained in the second temperature range of 700 ํ up to the temperature for cooling. Entering the sink for galvanizing ranges from 15 to 400 seconds and galvanizing the next order. The result is It is possible to obtain a microstructure containing ferrite phase with Fractions by area in the range 75 to 90% relative to all microstructures. And the second cycle Containing perlite, where fraction by area ranges from 10 to 25%, and therefore, plated steel plate High strength zinc with excellent formability with high strength, that is, the tensile strength TS 540 Mpa or higher and the excellent flat-stretched flange condition can be achieved. Maperlite is 70% or more. In terms of fractions where area is relative to region cycle All second And the mean grain size of perlite was 5 micrometers or less.

Claims (6)

Claims (all) which will not appear on the advertisement page: Amendment 04/19/2019 Claims 1. High strength galvanized steel sheet that has been formed. Excellent shape, which consists of a sheet of basic steel and a galvanized layer on it. Steel plate surface Where the steel is a high strength steel plate containing a compound that Including, by mass%, carbon (C) 0.08 to 0.15%, silicon (Si) 0.5 to 1.5%, montanese (Mn) 0.5 to 1.5%, phosphorus (P) 0.1%. Or less, Sulfur (S) 0.01% or less, Aluminum (Al) 0.01 to 0.1%, Nitrogen (N) 0.005% or less. May be optionally added to boron (B) 0.0003 to 0.0050%, chromium (Cr) 0.05 to 0.5%, vanadium (V) 0.005 to 0.2%, molybdenum (Mo) 0.005 to 0.2%, titanium (Ti) 0.01 to. 0.1%, Niobium (Nb) 0.01 to 0.1%, Nickel (Ni) 0.05 to 0.5%, Gold (Cu) 0.05 to 0.5%, Calcium (Ca) 0.001 to 0.005%, Rare Barth Mineral (REM)) 0.001 to 0.005% and iron (Fe) that can be balanced with inevitable impurities. The microstructure that contains Ferrite phase is the main phase and the second phase that includes at least perlite, ferrite phase ranges from 75 to 90% and perlite is in the The range of 10 to 25% in terms of fractions by area. Relative to all microstructures; The mean grain size of perlite is 5 μm or less, and perlite has a fraction where the area is 0% or more. Relative to the entire area Of the second cycle ----------- 1. High strength galvanized steel sheet with excellent formability. Steel that is the basic iron sheet and the galvanized layer on the surface of the steel plate. Where the steel plate It is a high-strength steel plate containing a compound containing,% by mass, C 0.08 to 0.15%, Si 0.5 to 1.5%, Mn 0.5 to 1.5%, P0.1% or less, S 0.01% or less. Moreover, Al 0.01 to 0.1%, N0.005% or less, and the balance fraction is Fe, as well as the inevitable impurities. And the microstructure consists of the region cycle Ferrites are the main phase and the second phase consists of at least perlite, the ferrite cycle ranges from 75 to 90% and perlite ranges from 10 to 25%. Fractions by area In relation to all microstructures, the mean grain size of perlite is 5 μm or less, and perlite is fractions where area is 70% or more relative to area. 2. High-strength galvanized steel sheet in accordance with claim 1, where the mixture is combined. Further, one or more elements selected from Cr 0.05 to 0.5%, V 0.005 to 0.2%, and Mo 0.005 to 0.2% by mass 3. High-strength galvanized steel sheet according to claim 1. Or 2 places where the mixture is Further included with one or two elements selected from Ti 0.01 to 0.1% and Nb 0.01 to 0.1% by mass 4. High strength galvanized steel sheet as per claim 1 to 3. Where Mixture is further included. B 0.0003 to 0.0050% p.% By mass 5. High strength galvanized steel sheet in accordance with Claim 1 to 4, where The mixtures are further combined with one or two elements selected from Ni 0.05 to 0.5% and Cu 0.05 to 0.5% by mass. 6. High-strength galvanized steel plates according to Claim 1 to 5. Any one where The mixture is further combined with one or two elements selected from Ca 0.001 to 0.005% and REM 0.001 to 0.005% by% by mass 7. High-strength galvanized steel plates according to Claim 1 to 6. Any one where the plating layer Zinc is the layer of galvanization by annealing. 8. Method for producing high-strength galvanized steel sheet with excellent formability. It consists of a hot rolling process by making the steel under hot rolling to form hot rolled steel, hot rolled acid immersion, continuous annealing process by annealing the steel sheet. Hot is under annealing in the following order. And the next step is to cool down to the temperature for Entering the sink for galvanization And after the continuous annealing process, the galvanization process By galvanizing operations to form a galvanized layer on the surface of the hot rolled steel sheet by dipping the sheet. Hot rolled steel into a bath for galvanizing, continuous annealing and quenching steps. Zinc is continuously processed with a continuous galvanizing route, to produce sheets. Galvanized steel with a zinc layer raised on the surface of the sheet, where the steel contains a mixture of,% by mass, C 0.08 to 0.15%, Si 0.5 to 1.5%, Mn 0.5 to 1.5%, P 0.1% or less, S 0.01% or less, Al 0.01 to 0.1% N 0.005% or less, and the equilibrium fraction Fe as well as inevitable impurities, annealing has been performed. Constant The steel plate is placed in the temperature range of the Ac1 deformation point to the Ac3 deformation for 5 to 400 s, and in the post cooling, the steel plate is cooled from the temperature range one to 700. ํ at an average cooling rate of 5 ํ / sec or higher. And the time remained in the second temperature range at 700 ํ up to the bath temperature for galvanization in the range of 15 to 400 s. 9. Methods for producing high strength steel plates according to claim 8 at The process of rolling Hot consists of heating the steel at 1100 ํ to 1280 ํ, the heating of the steel. Under hot rolling with a finished hot rolling temperature of 870 ํ to 950 ํ for hot rolled coil forming, and after hot rolling, hot rolled coil is coiled at 350 ํ to 720 ํ 1. 0. Method for producing high-strength galvanized steel sheet according to claim 8 or 9, where the cooling time in the temperature range 700 ํ 550 ํ in the second temperature range is 10 s or longer. 1 1. A method for the manufacture of high-strength galvanized sheet steel in accordance with any of Clause 8 to 10, where the doping procedure for the dosing of the galvanized layer is proceeded from the procedure. Galvanization 1 2. Method for the manufacture of high-strength galvanized sheet steel according to any claim 8 to 11, where the mixture is further combined with one or more elements selected from Cr 0.05 to 0.5. %, V 0.005 to 0.2% and Mo 0.005 to 0.2% by% by mass 1. 3. Method for the production of high-strength galvanized sheet steel according to any claim 8 to 12, where the mixture is further combined with one or two elements selected from Ti 0.01 to 0.1%. And Nb 0.01 to 0.1% by% by mass 1 4. Method for the production of high-strength galvanized sheet steel according to any claim 8 to 13, where the mixture is further compounded by B 0.0003 to 0.0050% by% by mass 1. 5. Method for the manufacture of high-strength galvanized sheet steel according to any Clause 8 to 14, where the mixture is further compounded by one or two elements selected from Ni 0.05 to 0.5%. And Cu 0.05 to 0.5% by% by mass 1 6.A method for the manufacture of high-strength galvanized sheet steel according to any claim 8 to 15, where the mixture is further combined with one or two elements selected from Ca 0.001 to 0.005%. And REM 0.001 to 0.005% by% by mass.