High-carbon steel continuous casting capping method

Abstract

The invention discloses a high-carbon steel continuous casting capping method, which belongs to the technical field of metallurgy, and comprises the following steps: after entering a capping stage, reducing the pulling speed for multiple times until the pulling speed is reduced to 0.1 mm / min, stirring the liquid level of molten steel, and after the capping surface moves to a specified position below the initial liquid level of a crystallizer, fetching water and cooling liquid slag until black liquid slag is formed; the liquid slag is scraped off, and then water is fetched again; when the top sealing surface is a certain distance away from the lower opening of the crystallizer, cooling water of the bent section is closed, and cooling water of the horizontal section is closed when the tail blank moves to the horizontal section; and after it is confirmed that the top sealing face is completely sealed, the pulling speed is controlled to be increased repeatedly from 0.1 mm / min, and when the steel billet enters the arc-shaped section and is not cut, the pulling speed is increased to 2-2.5 m / min. According to the invention, the problems that high-carbon steel is easy to crack due to over-strong cooling during continuous casting and capping, tail blank meat falls off, and even bleed-out accidents are caused by molten steel extrusion in the continuous casting process are solved, and stable continuous casting production of the high-carbon steel is realized.

Description

Technical Field

[0001] This invention belongs to the field of metallurgical technology, specifically relating to a method for capping high-carbon steel continuous casting. Background Technology

[0002] High-carbon alloy steel, due to its high hardness, is mainly used in tool steel and ball bearing steel for manufacturing machining tools and cutting tools. However, this type of steel has poor toughness. During the production process of vertical bending continuous casting machines, because high-carbon alloy steel has less cooling shrinkage, and also has less slag consumption and thicker liquid slag in the crystallizer, it is very easy to cause quality defects such as cracks and tail billet loss due to excessive cooling during continuous casting capping. In some cases, it can even cause steel leakage accidents due to molten steel being squeezed out during continuous casting. Summary of the Invention

[0003] To address some or all of the technical problems existing in the prior art, the present invention provides a method for capping high-carbon steel continuous casting.

[0004] The method for capping high-carbon steel continuous casting provided by this invention includes:

[0005] (1) Speed ​​increase and decrease gradient control

[0006] After entering the capping stage, the pulling speed is reduced every 30-95 seconds until it drops to 0.1 mm / min, with each reduction controlled at 0.15-0.35 mm / min.

[0007] (2) Water cooling control of the capping surface

[0008] The surface of the molten steel is stirred. After stirring, when the top surface of the billet moves to a position 200-400mm below the initial liquid level in the crystallizer, water is sprayed to cool the slag until black slag is formed.

[0009] (3) Local slag scraping control on the capping surface

[0010] After scraping off the cooled liquid residue, water is added again.

[0011] (4) Cooling water shut-off control

[0012] When the top surface of the billet is 50-200mm away from the bottom of the crystallizer, turn off the cooling water in the bending section; when the tail of the billet reaches the horizontal section, turn off the cooling water in the horizontal section.

[0013] (5) Acceleration gradient control

[0014] After confirming that the top surface of the billet is completely sealed, control the casting speed to increase once every 5-45 seconds from 0.1 mm / min, with a single speed increase adjustment of 0.1-0.4 mm / min. When the billet enters the arc section and is not cut, increase the casting speed to 2-2.5 m / min.

[0015] Furthermore, in the local slag scraping control, an iron pipe with one end flattened into a shovel shape is used for local slag scraping.

[0016] The method for capping high-carbon steel continuous casting of the present invention has the following advantages and beneficial effects:

[0017] This invention solves the problem that high-carbon steel is prone to cracking, billet loss, and even steel leakage accidents caused by excessive cooling during continuous casting capping by reducing casting speed, water spraying and slag scraping at the top surface, weak cooling of the tail billet, shortening the feeding and speed reduction, and then quickly increasing the casting speed of the tail billet. It achieves stable continuous casting production of high-carbon steel. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only for further understanding of the embodiments of the present invention and constitute a part of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. In the drawings:

[0019] Figure 1 This is a process flow diagram of the high-carbon steel continuous casting capping method of the present invention. Detailed Implementation

[0020] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below in conjunction with specific embodiments and corresponding drawings. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0021] See Figure 1 The method for capping high-carbon steel continuous casting provided by the present invention includes:

[0022] (1) Speed ​​increase and decrease gradient control

[0023] After entering the capping stage, the pulling speed is reduced every 30-95 seconds until it drops to 0.1 mm / min, with each reduction controlled at 0.15-0.35 mm / min.

[0024] (2) Water cooling control of the capping surface

[0025] The surface of the molten steel is stirred. After stirring, when the top surface of the billet moves to a position 200-400mm below the initial liquid level in the crystallizer, water is sprayed to cool the slag until black slag is formed.

[0026] (3) Local slag scraping control on the capping surface

[0027] After the liquid slag has cooled, use an iron pipe with one end flattened into a shovel shape to locally scrape off the slag, and then pump water again.

[0028] (4) Cooling water shut-off control

[0029] When the top surface of the billet is 50-200mm away from the bottom of the crystallizer, turn off the cooling water in the bending section; when the tail of the billet reaches the horizontal section, turn off the cooling water in the horizontal section.

[0030] (5) Acceleration gradient control

[0031] After confirming that the top surface of the billet is completely sealed, control the casting speed to increase once every 5-45 seconds from 0.1 mm / min, with a single speed increase adjustment of 0.1-0.4 mm / min. When the billet enters the arc section and is not cut, increase the casting speed to 2-2.5 m / min.

[0032] The method for sealing high-carbon steel continuous casting according to the present invention is further illustrated below with reference to specific embodiments.

[0033] Example 1

[0034] In Example 1 of this invention, the chemical composition of the molten steel by mass percentage is: C=0.6-0.64%; Si=1.63-1.81%; Mn=0.75-0.95%; P≤0.015%; S≤0.005%; Al=0.015-0.03%; Cr=0.1-0.18%; N≤0.005%; the remainder is Fe and unavoidable impurities. The cross-sectional dimensions of the cast billet are 230*1280mm. The method for capping the high-carbon steel continuous casting in Example 1 specifically includes:

[0035] (1) Speed ​​increase and decrease gradient control

[0036] After entering the capping stage, the initial pulling speed is 1.00 m / min; after 70 seconds, it is adjusted to 0.75 m / min; after 70 seconds, it is adjusted to 0.55 m / min; after 70 seconds, it is adjusted to 0.3 m / min and the crystallizer is switched to machine cleaning mode, and after 70 seconds, it is adjusted to 0.1 m / min.

[0037] (2) Water cooling control of the capping surface

[0038] The surface of the molten steel is stirred. After stirring, when the top surface of the billet moves to a position 250mm below the initial liquid level in the crystallizer, water is applied to cool the slag until black slag is formed.

[0039] (3) Local slag scraping control on the capping surface

[0040] After the liquid slag has cooled, use an iron pipe with one end flattened into a shovel shape to locally scrape off the slag, and then pump water again.

[0041] (4) Cooling water shut-off control

[0042] When the top surface of the billet is 150mm away from the bottom of the crystallizer, the cooling water in the bending section is turned off; when the tail of the billet reaches the horizontal section, the cooling water in the horizontal section is turned off.

[0043] (5) Acceleration gradient control

[0044] After confirming that the top surface of the billet is completely sealed, control the casting speed and adjust it sequentially every 30 seconds from 0.1 mm / min to: 0.2 m / min - 0.35 m / min - 0.55 m / min - 0.85 m / min - 1.15 m / min. When the billet enters the arc section and is not cut, increase the casting speed to 2 m / min.

[0045] Testing revealed that the billet produced in Example 1 showed no signs of chipping or cracking, and no molten steel was extruded during the continuous casting process.

[0046] Example 2

[0047] In Example 2 of this invention, the chemical composition of the molten steel by mass percentage is: C=0.63-0.68%; Si=0.2-0.3%; Mn=1-1.15%; P≤0.015%; S≤0.005%; Al=0.015-0.03%; Cr≤0.04%; Ni≤0.04%; Cu≤0.02%; N≤0.005%; the remainder is Fe and unavoidable impurities. The cross-sectional dimensions of the cast billet are 230×1540mm. The method for capping the high-carbon steel continuous casting in Example 2 specifically includes:

[0048] (1) Speed ​​increase and decrease gradient control

[0049] After entering the capping stage, the initial pulling speed is 0.85 m / min; after an interval of 70 s, it is adjusted to 0.75 m / min; after an interval of 70 s, it is adjusted to 0.55 m / min; after an interval of 70 s, it is adjusted to 0.3 m / min and the crystallizer is switched to machine cleaning mode, and after an interval of 70 s, it is adjusted to 0.1 m / min.

[0050] (2) Water cooling control of the capping surface

[0051] The surface of the molten steel is stirred. After stirring, when the top surface of the billet moves to a position 200mm below the initial liquid level in the crystallizer, water is sprayed to cool the slag until black slag is formed.

[0052] (3) Local slag scraping control on the capping surface

[0053] After the liquid slag has cooled, use an iron pipe with one end flattened into a shovel shape to locally scrape off the slag, and then pump water again.

[0054] (4) Cooling water shut-off control

[0055] When the top surface of the billet is 200mm away from the bottom of the crystallizer, turn off the cooling water in the bending section; when the tail of the billet reaches the horizontal section, turn off the cooling water in the horizontal section.

[0056] (5) Acceleration gradient control

[0057] After confirming that the top surface of the billet is completely sealed, control the casting speed at 0.1 m / min. After 15 seconds, adjust it to 0.2 m / min, 0.35 m / min, 0.45 m / min, 0.65 m / min, 0.85 m / min, and 1.2 m / min. When the billet enters the arc section and is not cut, increase the casting speed to 2 m / min.

[0058] Testing revealed that the billet produced in Example 2 had no defects such as missing filler or cracks, and no molten steel was extruded during the continuous casting process.

[0059] In summary, this invention solves the problem that high-carbon steel is prone to cracking, billet loss, and even steel leakage accidents caused by excessive cooling during continuous casting capping by a method of speed reduction, water spraying and slag scraping at the capping surface, weak cooling of the tail billet, shortening and feeding to reduce speed, and rapid increase of the tail billet pulling speed. This invention achieves stable continuous casting production of high-carbon steel.

[0060] It should be noted that, unless otherwise specified, the terms used herein have the meanings commonly understood by those skilled in the art. Furthermore, when a numerical range is disclosed herein, the range is considered continuous and includes the minimum and maximum values ​​of the range, as well as every value between such minimum and maximum. Further, when the range refers to integers, it includes every integer between the minimum and maximum values ​​of the range. Moreover, when multiple ranges are provided to describe features, the ranges may be combined. In other words, unless otherwise specified, all ranges disclosed herein should be understood to include any and all subranges to which they are incorporated.

[0061] It should also be noted that, in this document, the term "comprising" or any other variation thereof is intended to cover non-exclusive inclusion, such that an article or device that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such an article or device.

[0062] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the present invention.

Claims

1. A method of high carbon steel continuous casting capping, characterized in that, Comprise: (1) The speed gradient control of the drawing speed After entering the capping stage, the drawing speed is reduced every 30-95s until the drawing speed is reduced to 0.1mm / min, and the single reduction adjustment amount is controlled to be 0.15-0.35mm / min; (2) The water cooling control of the capping surface The liquid surface of the molten steel is stirred, after the stirring is completed, when the capping surface of the casting blank moves to the position 200-400mm below the initial liquid surface of the crystallizer, the casting blank is cooled by water and slag, until the black liquid slag is formed; (3) The local slag scraping control of the capping surface After the cooled liquid slag is scraped, water is sprayed again; (4) The cooling water closing control When the capping surface of the casting blank is 50-200mm away from the lower opening of the crystallizer, the cooling water of the bending section is closed, and when the tail blank of the casting blank reaches the horizontal section, the cooling water of the horizontal section is closed; (5) The speed gradient control of the rising speed After confirming that the capping surface of the casting blank is completely capped, the drawing speed is controlled to be increased every 5-45s, and the single speed adjustment amount is controlled to be 0.1-0.4mm / min, when the casting blank enters the arc-shaped section and does not cut, the drawing speed is increased to 2-2.5m / min.

2. The method of high carbon steel continuous-casting capping according to claim 1, characterized in that, In the local slag scraping control, an iron pipe with one end flattened to form a shovel shape is used for local slag scraping.

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