TWI490339B - Method of making steel - Google Patents

Description

Steelmaking method

The present invention relates to a steelmaking process, and more particularly to a steelmaking process suitable for use in a top-blown steelmaking apparatus.

The steelmaking method suitable for vacuum cycle top-blowing oxygen decarburization and degassing device is to perform a degassing process after adding aluminum metal, thereby removing oxygen in the molten steel, thereby improving the quality of the molten steel. However, the conventional method is to introduce aluminum metal into the degassing process at the initial stage of steel making, and it is easy to cause impurities in the molten steel to form a large medium, thereby reducing the cleanliness of the molten steel.

The above-mentioned "vacuum cycle top-blowing oxygen decarburization and degassing device" refers to a top blowing steelmaking method (Ruhstahl-Heraeus Kawasaki Top Blowing; RH-KTB) modified by Kawasaki Steel Co., Ltd., which is attached to a conventional RH vacuum chamber. An oxygen lance is installed on the top, and during the degassing process, oxygen is simultaneously blown to perform the decarburization process.

In order to solve the above-mentioned defects of poor cleanliness, a common method is to extend the slag of the molten steel surface to the surface of the molten steel by prolonging the weak stirring time in the later steelmaking period so that the impurities in the molten steel adhere to the surface of the introduced bubble. Medium, and can shorten the floating time of impurities. The aforementioned "weak agitation" means A weak gas (for example, argon gas) is introduced into the bottom of the steelmaking furnace, and the impurities in the molten steel are adhered to the surface of the bubble by the air bubbles, so that the impurities in the molten steel can be brought to the slag of the molten steel surface, and shortened. The floating time of the impurities can further improve the quality of the molten steel.

However, this method increases the time required for the steelmaking process and increases the time cost, which in turn cannot meet the requirements of rapid continuous production.

Another method is to extend the interval between the steelmaking process and the subsequent casting process, so that the impurities in the molten steel have sufficient time to fully float up to the slag of the molten steel surface, and the molten steel for the casting process can be cleaned. Degree, and thus avoid the defects of the steel produced by the casting process. Similarly, this method also increases the time cost of the steelmaking process and does not meet the requirements of rapid continuous production.

In view of this, it is not necessary to provide a steelmaking method to improve the drawbacks of the conventional steelmaking method applicable to RH-KTB.

Therefore, one aspect of the present invention provides a steelmaking method suitable for RH-KTB, which adjusts the aluminum casting time of the steelmaking method to improve the cleanliness of the molten steel.

According to the above aspect of the invention, a steelmaking method suitable for RH-KTB is proposed. In one embodiment, the method first provides a first molten steel, and performs a decarburization process on the first molten steel to form a second molten steel, wherein the first molten steel has a plurality of intervening materials, and the first molten steel The oxygen concentration is greater than 582 ppm and the carbon concentration of the second molten steel is less than 5 ppm. Then, add the first The amount of aluminum metal is used in the second molten steel, and oxygen is introduced to form a third molten steel, wherein the temperature of the third molten steel is greater than 1600 °C. Next, a deoxidation process is performed, and the second amount of aluminum metal is added to the third molten steel to form a fourth molten steel. The oxygen concentration of the fourth molten steel is less than 5 ppm, and the size of the intermediate in the fourth molten steel is less than 20 microns.

According to an embodiment of the invention, the first use amount of the aluminum metal is 200 kg to 450 kg per ton of the first molten steel, and the second use amount of the aluminum metal is 300 kg to 400 kg.

According to another embodiment of the present invention, after the deoxidation process described above, the steelmaking process further includes an alloying process for adding a metal to the fourth molten steel.

According to still another embodiment of the present invention, the foregoing metal may include electrolytic manganese, titanium metal, and any combination of the above metals.

By applying the steelmaking method of the present invention, by adjusting the timing of the aluminum casting of RH-KTB, the metal in the molten steel can be prevented from forming a large intervening substance, thereby improving the cleanliness of the molten steel and improving the quality of the steel.

100‧‧‧ method

110‧‧‧ Providing the first molten steel

120‧‧‧Decarbonation process to form second molten steel

130‧‧‧Add the first amount of aluminum metal to the second molten steel to form the third molten steel

140‧‧‧Deoxidation process

150‧‧‧Get the fourth molten steel

1 is a flow chart showing a steelmaking method according to an embodiment of the present invention.

Please refer to FIG. 1 , which is a flow chart showing a steel making method according to an embodiment of the present invention. In an embodiment, it is suitable for RH-KTB The steel method 100 first performs a process 110 for supplying a first molten steel, and performs a process 120 on the first molten steel, and the process 120 performs a decarburization process 120 on the first molten steel to form a second molten steel, wherein the first steel The liquid has a plurality of intervening materials, and the oxygen concentration of the first molten steel is greater than 582 ppm, and the carbon concentration of the second molten steel is less than 5 ppm.

Process 130 is then performed. The process 130 adds a first amount of aluminum metal to the second molten steel, and introduces oxygen to raise the temperature of the molten steel to form a third molten steel, wherein the temperature of the third molten steel is greater than 1600 °C. In one embodiment, the first amount of aluminum metal used is from 200 kilograms to 450 kilograms per ton of the first molten steel. In another embodiment, the first amount of aluminum metal used is 207 kilograms per ton of the first molten steel.

Next, a deoxidation process 140 is performed. The deoxidation process 140 is to add a second amount of aluminum metal to the third molten steel. After the deoxidation process 140 is performed, the steelmaking process can obtain the fourth molten steel 150, wherein the fourth molten steel has an oxygen concentration of less than 5 ppm, and the medium in the fourth molten steel has a size of less than 20 micrometers. In one embodiment, the second amount of aluminum metal used is from 300 kilograms to 400 kilograms per ton of the first molten steel. In another embodiment, the second amount of aluminum metal used is 369 kilograms per ton of the first molten steel.

In one embodiment, the steelmaking process can be selectively subjected to an alloying process after the deoxidation process 140 is performed. The alloying process adds a metal to the second molten steel to enhance the properties of the cast steel and to meet the use of the steel. In one embodiment, the metal described above may comprise electrolytic manganese, titanium metal, other suitable metallic materials, and any combination of the foregoing.

Metal formation in molten steel can be avoided by the steelmaking method of the present invention A large intervening material can improve the cleanliness of the molten steel, wherein the size of the medium in the molten steel is less than 20 microns.

The following examples are used to illustrate the application of the present invention, and are not intended to limit the present invention, and various modifications and refinements can be made without departing from the spirit and scope of the invention.

Example

First, the molten steel was poured into a steelmaking furnace in which the oxygen concentration of the molten steel was 582 ppm and the temperature was 1614 °C. Then, oxygen is introduced to raise the oxygen concentration in the molten steel to carry out the decarburization process, and at the same time, 105 kg of electrolytic manganese is added to each ton of molten steel to improve the quality of the molten steel. After the decarburization process, the temperature of the molten steel was 1576 ° C, and the oxygen concentration in the molten steel was 580 ppm. Next, 207 kg of aluminum metal was added per ton of molten steel, and oxygen was introduced to raise the temperature of the molten steel to 1600 °C. Thereafter, 369 kg of aluminum metal was added to each ton of molten steel for the deoxidation process. At the end of the deoxidation process, the oxygen concentration of the molten steel is 3 ppm, and the temperature of the molten steel is 1616 °C. Then, 113 kg of electrolytic manganese and 140 kg of titanium metal were added to the alloying process per ton of molten steel, and 18 kg of aluminum metal was added to carry out the deoxidation process to slightly reduce the oxygen concentration in the molten steel. The molten steel obtained in the examples had an oxygen concentration of 3 ppm and a temperature of 1621 °C.

Comparative example

First, the molten steel was poured into a steelmaking furnace in which the oxygen concentration of the molten steel was 479 ppm and the temperature was 1591 °C. Then, add 251 kg per ton of molten steel. The aluminum metal is transferred into the steelmaking furnace and oxygen is introduced to raise the temperature of the molten steel. Next, 280 kg of aluminum metal was added per ton of molten steel for the deoxidation process. After 4 minutes, the oxygen concentration in the molten steel was 4 ppm and the temperature was 1602 °C. After that, 266 kg of titanium metal was added per ton of molten steel to carry out the alloying process, and 10 kg of aluminum metal was added for the deoxidation process to slightly reduce the oxygen concentration in the molten steel. The molten steel obtained in the comparative example had an oxygen concentration of 4 ppm and a temperature of 1594 °C.

In the steelmaking process of the examples, the intervening material in the molten steel was measured by an electron microscope, and its size was less than 20 μm (not shown).

The apparatus in the comparative example was observed by the same apparatus and method as the foregoing examples, and the median size in the molten steel was 15 micrometers to 20 in the initial stage of the steelmaking process (6 minutes in the steelmaking process). Micron, and it is a spinel structure (not shown).

As the steelmaking process progresses, an electron microscope can observe a banana-like intermediate and its size is greater than 20 microns (not shown). These banana-like forms are formed by the added aluminum metal, the titanium metal in the alloying process, and the calcium metal in the slag.

However, these banana-like forms are unstable in the system. Therefore, at the end of the steelmaking process (15 minutes during the steelmaking process), a starfish-like intervening material formed of alumina was observed by an electron microscope, and its size was greater than 30 μm (not shown).

It can be seen from the above embodiments of the present invention that the steelmaking method of the present invention has the advantage of adjusting the timing of aluminum injection of RH-KTB at the end of RH-KTB. The addition of aluminum metal prevents the metal in the molten steel from forming a large intervening material, thereby improving the cleanliness of the molten steel, thereby improving the quality of the molten steel and avoiding defects in the steel. The size of the medium in the molten steel obtained by the steel making method of the present invention is less than 20 μm, so the steel making method can effectively improve the cleanliness of the molten steel, and can improve the quality of the obtained steel.

The present invention has been disclosed in the above embodiments, and is not intended to limit the present invention. Any one of ordinary skill in the art to which the present invention pertains can make various changes without departing from the spirit and scope of the invention. The scope of protection of the present invention is therefore defined by the scope of the appended claims.

100‧‧‧ method

110‧‧‧ Providing the first molten steel

120‧‧‧Decarbonation process to form second molten steel

130‧‧‧Add the first amount of aluminum metal to the second molten steel to form the third molten steel

140‧‧‧Deoxidation process

150‧‧‧Get the fourth molten steel

Claims (3)

The invention relates to a steelmaking method, which is suitable for a vacuum cycle top-blowing oxygen decarburization and degassing device, comprising: providing a first molten steel, wherein the first molten steel has a plurality of intervening substances, and the first molten steel has an oxygen concentration of 582 ppm Performing a decarburization process on the first molten steel to form a second molten steel; adding a first use amount of aluminum metal to the second molten steel, and introducing oxygen to form a third molten steel, Wherein the first usage amount is 200 kg to 450 kg per ton of the first molten steel, and the temperature of the third molten steel is greater than 1600 ° C; and performing a deoxidation process, wherein the deoxidation process is added a second The amount of the aluminum metal is used in the third molten steel to form a fourth molten steel having an oxygen concentration of less than 5 ppm, and the dielectrics of the fourth molten steel are less than 20 microns in size. Wherein the second usage amount is from 300 kg to 400 kg per ton of the first molten steel. The steelmaking method according to claim 1, after performing the deoxidation process, further comprises: performing an alloying process, wherein the alloying process adds a metal to the fourth molten steel. The steelmaking method according to claim 2, wherein the metal is selected from the group consisting of electrolytic manganese, titanium metal, and any combination thereof.