KR100931208B1 - Manufacturing method of ultra-thin surface treatment disc - Google Patents

Abstract

The present invention relates to a method for producing an ultrathin surface treated disc having excellent edge surface properties.

The present invention is in weight%, [C]: 0.005% or less, [Mn]: 0.3-0.5%, Sol. [Al]: 0.02-0.05%, [Ti]: 0.02-0.04%, [B]: 0.0005- 0.0015%, [N]: 0.004% or less, the ultra-low carbon aluminum-kilted steel composed of the remaining iron (Fe) and other unavoidable impurities, having a hot-rolled finish rolling temperature in the range of 920 to 950 ° C, and a bar heater or thermal cover and Edge heater (Edge Heater) is characterized in that it comprises a hot rolling while using more than 1,000kW while suppressing the temperature drop of the edge during hot rolling.

Polished car, surface treated disc, hot rolled finish temperature

Description

Method for manufacturing ultra-thin surface treatment disc {Method for manufacturing extremly thin blackplate for surface plate}

1 is a graph of a temperature distribution in a width direction of an edge region.

2 is a photograph showing representative edge surface properties.

Figure 3 is a hot rolled tissue photograph of the comparative example and the invention example.

4 is a graph showing the change in hardness from the edge.

5 is a graph showing changes in the roughness and glossiness of edges and centers.

The present invention relates to a method for manufacturing a highly processed ultra-thin surface treatment disc. More specifically, Mn, Al, Ti, and B are added to the ultra low carbon steel as a reinforcing element, and the hot rolling process is appropriately performed, thereby providing excellent edge surface properties. It is related with the manufacturing method of high strength ultra-thin surface treatment disc.

The high-strength ultra-thin surface treatment disk having excellent edge surface properties produced by the present invention is applied to a pail can or a camping gas cylinder which is expanded after tin seam and wire seam welding. Conventional surface treatment discs used for such applications include T2.5 to T3 produced by continuous annealing, as disclosed in Korean Patent Publication No. 2001-0064849 and Korean Patent Publication No. 1997-0033130.

In general, the edge of the ultrathin surface-treated disc should be managed in terms of quality as important as the center of the disc in terms of material utilization, quality, etc., but more disc defects such as an edge wave may occur than the center.

In addition, the steel of the prior art has a very high Ar3 temperature as a result of investigation by the inventors, and thus there is a deformation band in the surface layer from the edge to 30 to 40 mm. A band-shaped gloss difference defect having a width of 30 to 40 mm is generated from the edge of the surface, resulting in poor surface properties, and a gloss difference defect is more clearly observed after tin plating, thereby lowering product quality and a mistake rate.

In order to solve this problem, there is a method of side trimming the defect-producing portion of the surface treatment disc, but there are problems in terms of error rate, productivity, and manufacturing cost.

Therefore, the inventors of the present invention have conducted research and experiments to solve the above problems and proposed the present invention based on the results. The present invention controls the hot rolling process conditions of the steel, thereby providing excellent ultra-thin edge surface properties. It is an object of the present invention to provide a method for easily manufacturing a surface treatment disc.

The present invention is in weight%, [C]: 0.005% or less, [Mn]: 0.3-0.5%, Sol. [Al]: 0.02-0.05%, [Ti]: 0.02-0.04%, [B]: 0.0005- 0.0015%, [N]: 0.004% or less, the ultra-low-carbon aluminum-kilted steel composed of the remaining iron (Fe) and other unavoidable impurities, and the hot-rolled finish rolling temperature in the range of 920 ~ 950 ℃, bar or edge heater The present invention relates to a method for producing an ultra-thin surface treatment original plate having excellent edge surface characteristics by applying an energy of 1,000 kW or more to ensure that the temperature of the edge portion is 910 ° C or higher, which is an Ar3 temperature.

EMBODIMENT OF THE INVENTION Hereinafter, this invention is demonstrated in detail.

In the present invention, since the steel C contains a Ti content capable of sufficient precipitation with TiC even at 0.005%, the upper limit thereof is set at 0.005%.

Mn in steel is one of substitution type strengthening elements, and the lower limit was made into the lower limit 0.3% which exerts the strengthening effect by Mn addition, and 0.5% which is below the component limit limit on the specification was set as the upper limit.

Ti in the steel was set at the lower limit of 0.02%, which is a range capable of sufficiently removing solid solution carbon, and 0.04% was set at the upper limit in order to suppress rapid recrystallization temperature rise. In the present invention, the reason for suppressing the recrystallization temperature rise as much as possible is due to the continuous annealing temperature increase due to the recrystallization temperature rise, which causes wrinkles, plate dropping, plate breakage, etc. in the annealing furnace, and is a problem to be solved by the present invention. This is because the edge surface properties become poor.

When steel B is less than 0.0005%, it does not show grain growth inhibition during welding, and when it exceeds 0.0015%, the recrystallization temperature rapidly increases, and the content is set at 0.0005 to 0.0015%.

Since N in the steel combines with Ti to form TiN, when the content of N exceeds 0.004%, there is a shortage of residual Ti capable of depositing carbon, so that nitrogen is preferably added at 0.004% or less.

In steel, when Al is added too much Al content in the steel containing Ti of 0.03% level, Ar3 temperature rises and fine AlN precipitates before TiN, and there exists a problem of raising recrystallization temperature. Therefore, the content of Al in the steel was set to 0.02 to 0.05% in order to suppress rapid recrystallization temperature increase while ensuring sufficient strength.

Prior art Republic of Korea Publication No. 2001-0064849 discloses having an Al content of 0.08 ~ 0.2% as compared to the present invention is advantageous in improving the edge surface properties because it can lower the recrystallization temperature and Ar3 temperature.

Prior art Korean Patent Publication No. 1997-0033130 discloses a technique in which 0.04% to 0.06% Cr is added to 0.04% Al aluminum-killed ultra low carbon steel, whereas in the present invention, the recrystallization temperature is increased by not adding Cr. Since the surface area can be reduced, edge surface properties can be improved.

When hot-rolled using the ultra low carbon aluminum-kilted steel formed as described above, the edge is cooled as shown in FIG. 1 without proper management in operation due to a larger contact area with the atmosphere than the center. Big.

Therefore, in steels with relatively high recrystallization temperatures, such as ultra-low carbon aluminum-kilted steels, there is a need for a method capable of compensating for the edge temperature reduction in addition to appropriate selection of chemical composition.

The hot-rolled finish rolling temperature is not sufficiently recrystallized in the edge region by the edge temperature decrease when the finishing temperature is less than 920 ℃, the surface characteristics requirements are very difficult due to the abnormal surface scale when the finishing temperature is above 950 ℃ In order to suppress gloss difference defect generation by the edge temperature reduction and to suppress surface scale defect in this invention, since the operation | work cannot be performed in a surface treatment original plate, hot-rolled finish rolling temperature was limited to 920-950 degreeC.

In addition, in the present invention, the use of the edge heater of 1,000 kW or more is because an edge temperature increase effect of about 10 to 20 ° C. can be obtained than when the edge heater is not used.

The following describes the present invention through embodiments of the present invention.

Comparative steels, steels, and inventive steels were analyzed for test specimens manufactured under the field operating conditions, and the thickness was 0.23 mm, and the surface characteristics were visually judged. Grade 2 was classified as mild, poor or grade 1 when favorable.

Figure 2 is a photograph showing the gloss difference of both edges of the cold rolled steel sheet according to the degree of gloss difference. As shown in FIG. 2 (a), the gloss difference grade 1 is a state in which the gloss difference between the edge and the center is weak or almost absent, and the surface property is most favorable. As shown in FIG. 2 (c), in the case of the gloss difference grade 3, the gloss difference between the edge and the center is remarkably present, and the width is most clearly observed. As shown in FIG. 2 (b), the gloss difference can be clearly observed in the second degree of gloss difference, and the width thereof is shorter and weaker than the third degree.

As shown in Table 1 showing the chemical composition and the manufacturing conditions of the steel, and thus the degree of surface gloss difference, the comparative example shows a method for producing a surface treatment disc by a conventional method, the content of Mn is 0.23%, the content of B This 13 ppm and the Cr content is 0.05%, the hot rolling finish temperature is 910 ℃, no edge heater voltage is used. In this case, the content of B is high at 10 ppm or more, and Cr is added to increase the recrystallization temperature rapidly, and the degree of gloss difference is extreme as grade 3.

Examples 1-3 are cases where the Br content was lowered to suppress the recrystallization temperature increase, the Cr component was removed, the hot rolling finish temperature was 900 to 910 ° C., and the edge heater was not used. As for the Example, the degree of gloss difference was grade 2, and the degree of gloss difference was favorable compared with the comparative example.

Inventive Examples 4-6 are the case where it manufactured by the conditions similar to Examples 1-3, hot-rolling finishing temperature to 920-950 degreeC, and using the edge heater 600V or more. In the invention examples, the degree of gloss difference is 1 grade, which shows the best result than the gloss difference in Comparative Examples and Examples.

The cause of such edge gloss difference is as follows.

3 (a) and 3 (b) are 10 mm spot hot rolled tissue photographs at the edges in the comparative and inventive examples. As shown in Fig. 3 (a), the tissue of the comparative example is composed of unrecrystallized tissue in which no perfect grains are formed, whereas as shown in Fig. 3 (b), the tissue of the invention is recrystallized in which completely recrystallization has occurred. It is organized into organizations.

Such a difference in structure causes a difference in hardness values of the comparative example and the inventive example as shown in FIG. 4. That is, as shown in FIG. 4 (a), the comparative example shows a value of 50% higher in hardness than the center due to high density of dislocations in the non-recrystallized tissue, and shows a high hardness value up to about 40 mm.

On the other hand, as shown in Figure 4 (b), the hardness value of the invention example shows a uniform value compared to the center, unlike the comparative example.

5 (a) and 5 (b) show the difference in the roughness and glossiness of the surface of the annealing material due to the change in the hardness value due to the difference in the hot rolled structure of the comparative example and the invention example, respectively.

As shown in Fig. 5 (a), the Ra value of the comparative example is lower than the center at the edge, whereas the Ra value of the invention is relatively uniform. As a result, as shown in FIG. 5 (b), the gloss ratio at the edge and the center is about 30% or more in the comparative example, while the glossiness of the edge is higher than the center in the comparative example, while the glossiness is only about 10% in the invention. . Thus, edge surface gloss difference defects occur due to the relative difference in glossiness between the edge and the center.

As described above, the present invention adds reinforcing elements such as Mn, Al, Ti, and B to the ultra low carbon steel, controls the hot rolling finish temperature, and applies an edge heater, thereby providing ultra-thin surface treatment with excellent surface characteristics without edge gloss difference. There is an effect that can produce a disc.

Claims (1)

% By weight, [C]: 0.005% or less, [Mn]: 0.3% to 0.5%, Sol. [Al]: 0.02% to 0.05%, [Ti]: 0.02% to 0.04%, [B]: 0.0005% to 0.0015%, [N]: 0.004% or less, ultra-low carbon aluminum-killed steel composed of the remaining iron (Fe) and other unavoidable impurities, with a hot-rolled finish rolling temperature in the range of 920 to 950 ° C., bar heater or thermal cover and edge heater 1,000 A method for producing an ultrathin surface-treated master plate having excellent edge surface characteristics including hot rolling while using kW or more while suppressing a temperature drop of the edge during hot rolling.

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