TWI818628B - Method for removing slag on surfaces of steel slab, carbon steel and alloy steel - Google Patents

Abstract

The present invention relates to a method for removing slags on surfaces of a steel slab, a carbon steel and an alloy steel. The method maintains the steel slab after a burn-off process at a specific temperature and uses a water with a specific pressure to flush away the surfaces of the steel slab to remove the slags rapidly before the slags produced on the surfaces has not been solidified, therefore reducing time for removing the slags, and reducing manufacturing time for the carbon steel and the alloy steel.

Description

Methods for removing slag on the surface of steel blanks, carbon steel and alloy steel

The present invention relates to a method for removing molten slag from the surface of steel blanks and the carbon steel and alloy steel materials produced therefrom, and in particular to a method for removing molten slag from the surface of steel blanks by maintaining it at a specific temperature and the method thereof. Carbon steel and alloy steel produced.

After the large steel embryo undergoes the chain steel process, there will be many seam defects on the surface of the large steel embryo. In the early days, seam defects and decarburized layers could be improved by burning. However, during the burning process, the slag produced by the burning would splash around and adhere to the surface of the large steel blank, thus producing new slag. Surface defects. Recently, a secondary rust removal treatment has been developed, which uses a grinding wheel to grind the slag on the surface of the large steel blank to remove it.

However, this secondary rust removal process wastes manpower and electricity, and requires a large number of grinding wheels, thus increasing the cost. In view of this, there is an urgent need to develop a new method for removing slag from the surface of steel blanks to improve the above shortcomings.

In view of the above problems, one aspect of the present invention is to provide a method for removing slag on the surface of a steel blank. This removal method maintains the steel blank that has been burned at a specific temperature and flushes it with water at a specific pressure to quickly remove the slag on the surface of the steel blank.

Another aspect of the present invention provides a carbon steel material. This carbon steel is produced using the aforementioned method of removing slag from the surface of the steel blank.

Another aspect of the present invention provides an alloy steel material. This alloy steel is produced by using the aforementioned method of removing slag from the surface of the steel blank.

According to one aspect of the present invention, a method for removing molten slag on the surface of a steel blank is proposed. This removal method includes burning the steel blank obtained from steelmaking to obtain the burned steel blank; and removing the burned steel blank to remove slag. In the burning treatment, the burning temperature of the burning treatment is greater than 950°C and not greater than 1300°C, and molten slag is formed on the surface of the steel blank after burning. During the removal process, the temperature of the steel blank after burning is maintained at 950°C to 1100°C, and the surface is rinsed with water with a pressure of not less than 170 bar.

According to one embodiment of the present invention, before the removal treatment is performed, the removal method excludes a cooling treatment. The cooling treatment is to cool the burned steel blank to less than 950°C.

According to another embodiment of the present invention, during the removal process, the moving speed of the steel blank is 0.5m/sec to 1.5m/sec.

According to a further embodiment of the invention, the pressure is 170 bar to 220 bar.

According to another aspect of the present invention, a carbon steel material is provided. The carbon steel is produced by using the aforementioned method of removing slag from the surface of the steel blank, and the carbon steel includes low carbon steel and/or high carbon steel.

According to an embodiment of the present invention, the average spark time of low carbon steel is no more than 3 minutes.

According to another embodiment of the invention, the average spark time of the high carbon steel is no more than 4.5 minutes.

According to another aspect of the present invention, an alloy steel is provided. This alloy steel is produced by using the aforementioned method of removing slag from the surface of a steel blank. The alloy steel includes multi-component alloy steel and/or unit gold steel.

According to an embodiment of the present invention, the average spark time of the multi-component alloy steel is no more than 4.5 minutes.

According to another embodiment of the present invention, the average spark time of the unit alloy steel is no more than 7.5 minutes.

The method for removing molten slag on the surface of a steel blank is applied according to the present invention, in which the steel blank after being burned at a specific temperature is maintained at a specific temperature, and water at a specific pressure is used to flush the surface of the steel blank to remove the molten slag generated on the surface. Quickly remove the slag before it solidifies, thus shortening the slag removal time.

The making and using of embodiments of the invention are discussed in detail below. It is to be appreciated, however, that the embodiments provide many applicable inventive concepts that can be embodied in a wide variety of specific contexts. The specific embodiments discussed are illustrative only and are not intended to limit the scope of the invention.

The method for removing slag on the surface of steel blanks of the present invention is to maintain the steel blanks at 950°C to 1100°C after burning treatment at a temperature of greater than 950°C and not greater than 1300°C, and flush it with water at a pressure of not less than 170 bar. The surface of the steel blank is used to quickly remove the slag generated on the surface of the steel blank before it solidifies. Therefore, compared with the conventional method of using a grinding wheel to remove slag, the removal method of the present invention can eliminate the use of a grinding wheel and avoid the increased time required by using a grinding wheel, thereby shortening the time for removing slag and reducing the wear and tear of the grinding wheel. cost.

Please refer to FIG. 1 . In the method 100 for removing molten slag from the surface of the steel embryo, the steel embryo obtained from steelmaking is burned to obtain the burned steel embryo, as shown in operation 110 . In some embodiments, the steel blank may include a steel blank for manufacturing carbon steel and/or alloy steel.

The conditions of the steel-making process are those commonly used by those with ordinary knowledge in the technical field to which the present invention belongs, for example: a steel-making temperature of 1100°C to 1200°C. Furthermore, the burning treatment is used to improve the seam defects and decarburization layer of the steel blank after steelmaking. The steel blank after steelmaking is burned at a burning temperature of greater than 950°C and not greater than 1300°C, and during the burning treatment, molten slag will be formed on the surface of the burned steel blank. To elaborate, the high temperature of the burning treatment will partially melt the steel blank, thus forming slag on the surface of the burned steel blank. This slag degrades the quality of the steel produced and must be removed. If the burning temperature is not greater than 950°C, too low a temperature cannot improve the seam defects and decarburization layer of the steel blank after steelmaking. On the contrary, if the burning temperature is greater than 1300℃, too high temperature will produce too much slag.

After operation 110 is performed, a removal process is performed on the burned steel blank to remove slag, as shown in operation 120 . The aforementioned removal treatment is to maintain the temperature of the burned steel embryo at 950°C to 1100°C, and rinse the surface of the burned steel embryo with water having a pressure of not less than 170 bar to remove slag. The purpose of the aforementioned temperature maintenance is to ensure that the generated slag can be quickly removed before it solidifies.

If the burning temperature of the steel blank after burning is less than 950°C, the slag has solidified on the surface of the steel blank and cannot be removed with water. On the contrary, if the temperature of the steel blank after burning is greater than 1100°C, the surface of the steel blank will be in a superheated state, and the water will not be able to exert its flushing effect and the slag will not be removed.

In addition, if the water pressure is less than 170 bar, the water with too small pressure cannot remove the slag. Preferably, the water pressure may be from 170 bar to 220 bar. When the water pressure is 170 bar to 220 bar, the water can remove the slag without wasting water.

In some embodiments, the moving speed of the steel blank during the removal process may be 0.5 m/sec to 1.5 m/sec. When the moving speed is within the aforementioned range, there is sufficient contact time between the water and the slag to facilitate removal of the slag.

In a preferred embodiment, the removal method 100 excludes a cooling process before performing the removal process. When the temperature of the steel blank is maintained at no less than 950°C after burning, the generated slag will not solidify and is therefore easily removed.

In some application examples, the method 100 for removing molten slag on the surface of the steel blank can be carried out by using high-pressure nozzles. The number of high-pressure nozzles can be determined according to the area of the steel blank surface. For example, the larger the area, the more nozzles are used. At the same time, the slag is removed from the entire surface of the steel blank. In these application examples, there is no particular restriction on the spray direction of the nozzle and the normal line of the steel blank surface. Preferably, the two can present an angle of 70 degrees to 20 degrees.

Another aspect of the invention provides a carbon steel material. This carbon steel is produced using the aforementioned method of removing slag from the surface of the steel blank. Carbon steel may include low carbon steel and/or high carbon steel.

For example, low carbon steel may include steel with steel grade number AISI 1006, which contains no more than 0.08 weight percent carbon, 0.25 to 0.40 weight percent manganese, no more than 0.040 weight percent phosphorus, and no more than 0.050 weight percent. of sulfur. Secondly, the high carbon steel may include steel with the steel grade number AISI 1050, which contains 0.5 weight percent carbon, and the remaining constituent elements and contents are as known to those with ordinary knowledge in the technical field to which the present invention belongs.

Furthermore, the slag removal effect of the steel material produced was evaluated using the spark time test described below. For example, in low carbon steel implementations, the average spark time of low carbon steel is no greater than 3 minutes. In the implementation of high carbon steel, the average spark time of high carbon steel is no more than 4.5 minutes.

According to another aspect of the present invention, an alloy steel is provided. This alloy steel is produced by using the aforementioned method of removing slag from the surface of the steel blank. Alloy steel may include multi-element alloy steel and/or unit gold steel.

The unit gold steel of the present invention refers to a steel blank containing only one metal element, but it does not exclude metal elements that cannot be removed during the manufacturing process or must remain in a residual amount (such as less than 0.001 weight percent).

In addition, the multi-component alloy steel may include steel with steel grade number AISI 8620, which contains 0.5 weight percent chromium, 0.2 weight percent molybdenum and 0.5 weight percent nickel. Furthermore, the unit alloy steel may include steel with steel grade number AISI 5120, which contains 0.17 to 0.22 weight percent of carbon, 0.15 to 0.3 weight percent of silicon, 0.7 to 0.9 weight percent of manganese, not more than 0.035 weight percent iodine and no more than 0.04 weight percent sulfur.

In some embodiments, the average spark time of the multicomponent alloy steel may be no greater than 4.5 minutes. In other embodiments, the average spark time of the unit alloy steel may be no greater than 7.5 minutes.

According to the aforementioned average spark time results of carbon steel and alloy steel, the method for removing slag on the surface of steel blanks of the present invention can be applied to various types of steel. Preferably, the removal method can be applied to carbon steel (such as low carbon steel and high carbon steel) and multi-component alloy steel. Preferably, the removal method is more suitable for multi-component alloy steel.

Manufacturing of steel

Example 1

The steel material of Example 1 is manufactured by performing steelmaking treatment on the steel blank, and then burning the steel blank at a temperature of greater than 950°C and not greater than 1300°C, and immediately after the burning treatment, the steel blank is still in the Wash the surface of the steel blank with high-pressure water of 170 bar to 220 bar at 950°C to 1100°C. The moving speed of the steel blank is 0.5m/sec to 1.5m/sec to remove the slag generated by the burning process. The steel material of Example 1 is obtained by sequentially undergoing the processes of rough rolling, finish rolling, shearing and cooling. Then evaluate using the evaluation method described below.

Examples 2 to 4 and Comparative Examples 1 to 4

The steel materials of Examples 2 to 4 and Comparative Examples 1 to 4 were processed in a similar manner to Example 1. The difference is that Examples 2 to 4 and Comparative Examples 1 to 4 use different types of steel blanks, and Comparative Examples 1 to 4 are not removed. The specific conditions and evaluation results of the aforementioned Examples 1 to 4 and Comparative Examples 1 to 4 are shown in Table 1 below.

Evaluation method

Spark Test

The spark test was carried out by placing a silicon roller close to the surface of the steel produced in each of the examples and comparative examples. When there is molten slag on the surface of the steel, the rolling silicon roller will rub the slag and generate sparks. After the slag is removed, the spark disappears, so the time when the spark is generated is used to evaluate the effect of removing the slag. The shorter the spark generation time, the better the slag removal effect.

Table 1 AISA number Steel type Remove processing sample size Average spark time (minutes) Example 1 1006 Mild steel have 30 1.27 2 1050 high carbon steel have 67 3.63 3 8620 alloy steel have 70 3.54 4 5120 alloy steel have 25 5.69 Comparative example 1 1006 Mild steel not yet 30 3.27 2 1050 high carbon steel not yet 76 4.65 3 8620 alloy steel not yet 100 4.58 4 5120 alloy steel not yet 19 7.85

Please refer to Table 1. Compared with Comparative Example 1 that does not use removal treatment, the average spark time measured in Example 1 belonging to the same steel type (ie, low carbon steel) is shorter, that is, the slag removal effect is better. Similarly, the same results exist in the various examples and comparative examples corresponding to the same type of steel material, so the removal treatment can effectively remove the slag on the surface of the steel blank.

In addition, the time it takes to remove slag in these embodiments is shorter than the time required by the conventional method of using grinding wheels to remove slag. Therefore, these embodiments can shorten the time to remove slag and reduce the cost of using grinding wheels. cost.

To sum up, the method for removing slag on the surface of a steel embryo according to the present invention is to maintain the steel embryo at a specific temperature after being burned at a specific temperature, and use water at a specific pressure to rinse the surface of the steel embryo to generate slag on the surface. The slag is quickly removed before it solidifies, thereby shortening the slag removal time.

Although the present invention has been disclosed in the above embodiments, it is not intended to limit the present invention. Anyone with ordinary knowledge in the technical field to which the present invention belongs can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention shall be determined by the appended patent application scope.

100:Method 110,120: Operation

In order to have a more complete understanding of the embodiments of the present invention and its advantages, please refer to the following description together with the corresponding drawings. It must be emphasized that various features are not drawn to scale and are for illustration purposes only. The relevant diagram content is explained as follows: FIG. 1 is a flow chart illustrating a method for removing slag from the surface of a steel blank according to an embodiment of the present invention.

100:Method

110,120: Operation

Claims (9)

A method for removing slag on the surface of a steel embryo, which includes: performing a burning treatment on a steel embryo obtained from steelmaking to obtain a burned steel embryo, wherein the burning temperature of the burning treatment is greater than 950°C and The temperature is not greater than 1300°C, and a molten slag is formed on a surface of the burned steel embryo; and a removal process is performed on the burned steel embryo to remove the slag, wherein during the removal process, the burnt out The temperature of the steel blank is then maintained at 950°C to 1100°C, with a moving speed of 0.5m/sec to 1.5m/sec, and the surface is rinsed with water having a pressure of not less than 170 bar. The removal method as described in claim 1, wherein before performing the removal treatment, the removal method excludes a cooling treatment, and the cooling treatment is to reduce the temperature of the burned steel blank to less than 950°C. The removal method as claimed in claim 1, wherein the pressure is 170 bar to 220 bar. A carbon steel material produced by the method for removing slag on the surface of a steel blank as described in any one of claims 1 to 3, wherein the carbon steel material includes a low carbon steel and/or a high carbon steel. The carbon steel material as claimed in claim 4, wherein the average spark time of the low carbon steel is no more than 3 minutes. The carbon steel as claimed in claim 4, wherein the average spark time of one of the high carbon steels is no more than 4.5 minutes. An alloy steel produced by the method for removing slag on the surface of a steel blank as described in any one of claims 1 to 3, wherein the alloy steel includes a multi-component alloy steel and/or a unit gold steel. The alloy steel as claimed in claim 7, wherein the average spark time of one of the multi-element alloy steel is no more than 4.5 minutes. The alloy steel as claimed in claim 7, wherein the average spark time of one of the units of gold steel is no more than 7.5 minutes.

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