CN105803313B - A kind of thin-gauge hot-dip galvanized steel sheet and its production method - Google Patents

Abstract

The invention discloses a thin gauge hot-dip galvanized steel sheet, which comprises the following components in weight percentage: C: 0.0010% to 0.003%, Si: 0.01 to 0.03%, Mn: 0.10 to 0.16%, P: ≤0.010%, S : ≤0.009%, Als: 0.010-0.050%, Ti: 0.04%-0.07%, Nb: 0.005%-0.02%; the balance is Fe and unavoidable impurities. The invention also discloses a production method of the thin gauge hot-dip galvanized steel sheet. The invention forms a key technology for continuous annealing to produce thin-gauge hot-dip galvanized steel sheets. The invention has simple component design, large process control window, strong adaptability, and excellent product surface quality.

Description

A kind of thin-gauge hot-dip galvanized steel sheet and its production method

technical field

The present invention relates to a cold-rolled strip production technical field, in particular to a production method for continuous annealing to produce a thin-gauge hot-dip galvanized steel sheet, and the invention also relates to the thin-gauge hot-dip galvanized steel sheet.

Background technique

With the development of the automobile industry, the demand for high-strength and high-formability cold-rolled steel sheets required for automobile bodies is increasing, and there are more and more related technical researches. For example, in the Chinese patent application No. 200710048926.8, the patent document titled "Production method of deep-drawn skin-pass galvanized steel sheet" discloses that the components and weight percentages of the present invention are: C: 0.003～0.006%, :0.02～ 0.04%, the hot rolling coiling temperature is 70~780℃, and the cold rolling annealing temperature is 780~880℃. The yield strength of the finished product is about 180MPa, the tensile strength is about 310MPa, the elongation is about 42.0%, n is about 0.21, and r is about 1.9. Another example is in the Chinese patent application No. 201210338992.X, titled "A Hot-Dip Galvanized Steel Sheet for Automobiles and Its Production Method", which discloses that the composition and weight percentage of hot-dip galvanized steel sheets for automobiles is C: 0.001 ～0.003%, Si: ≤0.03%, Mn: 0.05～0.15%, P: ≤0.02%, S: 0.008～0.015%, Als: 0.02～0.07%, Ti: 0.05～0.09%, B: 0.0002～0.01% . The rest consists of Fe. The yield strength of the finished product is about 160MPa, the tensile strength is about 287MPa, the elongation is about 44.0%, the r ₉₀ value is about 2.4, and the n ₉₀ value is 0.24.

Contents of the invention

The object of the present invention is to provide a thin-gauge hot-dip galvanized steel sheet that is low in cost, less difficult in process implementation, and capable of mass production and a production method thereof.

In order to achieve the above-mentioned technical effect, the present invention takes the following technical solutions:

A thin-gauge hot-dip galvanized steel sheet, said thin-gauge hot-dip galvanized steel sheet comprising the following components by weight percentage: C: 0.0010%-0.003%, Si: 0.01-0.03%, Mn: 0.10-0.16%, P: ≤ 0.010%, S: ≤0.009%, Als: 0.010-0.050%, Ti: 0.04%-0.07%, Nb: 0.005%-0.02%; the balance is Fe and unavoidable impurities.

The invention also discloses a production method of the thin-gauge hot-dip galvanized steel sheet, which specifically includes:

According to the conventional steps of molten iron desulfurization, converter smelting, LF furnace Ca treatment, and RH decarburization, the composition of molten steel is controlled within the range mentioned above, and it is continuously cast into a continuous casting slab with a thickness of 200 mm, which is hot rolled and heated to 1200 ° C to 1240 ° C. Rough rolling is carried out at ℃. After rough rolling, the thickness of the intermediate slab is 33mm~36mm, and it is coiled by a coreless transfer hot coil box; the temperature range of hot rolling is 900℃~930℃; The cooling rate is cooled to 770 ~ 800 ° C for coiling. Combined with the capacity of the cold rolling mill, the cold rolling reduction rate is determined to be 80% to 85%. Then, after the cleaning process, the residual oil, iron oxide scale, iron powder, etc. on the surface of the strip steel are removed, and then enters the continuous annealing furnace. 470°C. After air knife purging and cooling, the skin elongation is controlled at 0.4-0.7%, and the tensile elongation is controlled within the range of 0.1-0.4%, followed by surface passivation treatment and coiling, that is, thin-gauge hot-dip coating Zinc steel.

The thin-gauge hot-dip galvanized steel sheet mentioned in this application refers to a hot-dip galvanized steel sheet with a thickness of 0.5 mm.

Compared with the prior art, the present invention has the following beneficial effects:

The thin gauge hot-dip galvanized steel sheet prepared by the invention has the mechanical properties of the finished product meeting the requirements of yield strength 120-160 MPa, tensile strength 270-310 MPa, elongation ≥ 46.0%, r ₉₀ ≥ 2.6, n ₉₀ ≥ 0.26. In addition, the invention forms a key technology for continuous annealing to produce thin-gauge hot-dip galvanized steel sheets. The invention has simple component design, large process control window, strong adaptability, and excellent product surface quality.

Description of drawings

The microstructure of the thin-gauge hot-dip galvanized steel sheet prepared by the present invention of Fig. 1 .

detailed description

The present invention will be further elaborated and illustrated below in conjunction with the embodiments of the present invention.

In the present invention, according to the usual molten iron desulfurization, converter smelting, LF furnace Ca treatment, RH decarburization, continuous casting into a 200mm thick continuous casting slab, the weight percentage of the chemical composition is: C: 0.002%, Si: 0.02%, Mn: 0.12 %, P: 0.004%, S: 0.006%, Als: 0.033%, Ti: 0.060%, Nb: 0.011%; the balance is Fe and unavoidable impurities. Hot rolling is heated to 1210°C for rough rolling. After rough rolling, the thickness of the intermediate slab is 35.0mm. It is coiled by a coreless transfer hot coil box. The finishing temperature of hot rolling is 916°C. Cool to 772°C for coiling. Hot rolling thickness 3.0mm. Combined with the capacity of the cold rolling mill, the cold rolling reduction rate is 83.3%, and the thickness of the cold rolled plate is 0.5mm. After the cleaning process, the residual oil, iron oxide scale, iron powder, etc. on the surface of the strip are removed, and then enter the continuous annealing furnace. The annealing soaking temperature is 835°C, the soaking time is 58s, and the temperature of the substrate entering the zinc pot is 460°C. Afterwards, air knife purging, cooling, skin finishing, and tensile straightening elongation are controlled within the ranges of 0.53% and 0.13%, respectively, and then surface passivation treatment and coiling are carried out. Finished surface is FC grade. Yield strength, tensile strength, elongation, n ₉₀ , r ₉₀ are 150MPa, 290MPa, 48.5%, 0.26, 2.9, respectively. The finished product is a 100% ferrite structure with a grain size of 8.0.

Accompanying drawing 1 is the microstructure of the thin gauge hot-dip galvanized steel sheet prepared by the present invention. It can be seen that the thin-gauge hot-dip galvanized steel sheet prepared by the present invention has a microstructure of 100% ferrite with fine and uniform crystal grains, which finally correspond to the mechanical properties.

The thin-gauge hot-dip galvanized steel sheet prepared by the present invention has performance comparable to that of the reference file under the thin-gauge (0.5mm), because generally speaking, the hot-dip galvanized steel sheet produced under the military 1mm condition measures relevant performance parameters of. At the same time, it should be pointed out that the thin-gauge hot-dip galvanized steel sheet prepared by the present application has an elongation rate of 48.5%, which is greatly improved on the basis of the reference document.

Although the present invention has been described here with reference to the illustrative examples of the present invention, the above-mentioned examples are only preferred implementations of the present invention, and the implementation of the present invention is not limited by the above-mentioned examples. It should be understood that those skilled in the art Many other modifications and embodiments can be devised which will fall within the scope and spirit of the principles disclosed in this application.

Claims (1)

1. A production method of thin gauge hot-dip galvanized steel sheet, characterized in that: According to the usual molten iron desulfurization, converter smelting, LF furnace Ca treatment, RH decarburization, continuous casting into 200mm thick continuous casting slab, the weight percentage of chemical composition is: C: 0.002%, Si: 0.02%, Mn: 0.12%, P: 0.004%, S: 0.006%, Als: 0.033%, Ti: 0.060%, Nb: 0.011%; the balance is Fe and unavoidable impurities; hot rolling is heated to 1210°C for rough rolling, and the intermediate slab after rough rolling The thickness is 35.0mm, and it is coiled by a coreless transfer hot coil box. The finishing temperature of the hot rolling is 916°C. The capacity of the rolling mill, the cold rolling reduction rate is 83.3%, and the thickness of the cold-rolled plate is 0.5mm; then, after the cleaning process, the residual oil, iron oxide scale, iron powder, etc. 835°C, the soaking time is 58s, and the temperature of the substrate entering the zinc pot is 460°C; followed by air knife purging and cooling, the elongation of skin pass and tension leveling are controlled within the range of 0.53% and 0.13% respectively, and then the surface is passivated Processing and coiling; the surface of the finished product is FC grade; the yield strength, tensile strength, elongation, n ₉₀ , r ₉₀ are 150MPa, 290MPa, 48.5%, 0.26, 2.9 respectively; the finished product is 100% ferrite structure, grain The granularity is 8.0 grade.