High-pulling-speed production process of 200mm*200mm continuous casting billet of high-carbon hard wire steel

Abstract

The invention provides a high-pulling-speed production process of a high-carbon hard-wire steel continuous casting billet, which comprises the following steps of: pouring refined molten steel in a steel ladle into a tundish for replacing the tundish, pouring the molten steel into a crystallizer of a continuous casting machine from the tundish, and cooling the molten steel through a secondary cooling area and an air cooling area under the pulling speed of the continuous casting machine to obtain the high-carbon hard-wire steel continuous casting billet. A continuous casting square billet with the section size being 200 mm * 200 mm is obtained; the pulling speed of the continuous casting machine ranges from 1.5 m / min to 2.5 m / min; and the secondary cooling specific water flow of the secondary cooling area is 0.6-0.9 L / kg. According to the method, the high-quality 200 mm * 200 mm continuous casting blank is obtained, and the advantages of high continuous casting efficiency and structure property regulation and control are better reflected. According to the method, high-pulling-speed production of the 200 mm * 200 mm continuous casting billet of the high-carbon hard wire steel is achieved, the production efficiency is effectively improved, the production cost is reduced, the product quality is improved, and cost reduction and efficiency improvement are achieved.

Description

Technical Field

[0001] The invention belongs to the technical field of high-carbon hard wire steel continuous casting billets, and relates to a high-drawing speed production process and application of high-carbon hard wire steel continuous casting billets, and in particular to a high-drawing speed production process of a high-carbon hard wire steel 200mm×200mm continuous casting billet. Background Art

[0002] High carbon hard wire steel is the main variety used to prepare high-strength cold-drawn steel wire. It is widely used in infrastructure construction and has important value for social development. For example, SWRH82B high carbon wire rod steel is the main raw material for the production of metal products such as prestressed steel wire, prestressed steel strand, high-strength steel wire and steel rope. Among them, the prestressed steel strand prepared with SWRH82B wire rod as raw material has been promoted and applied in my country's construction industry, and its development trend has continued to expand in recent years. In addition, this product is also widely used in marine engineering, energy engineering and water conservancy engineering and other fields. The product exhibits the characteristics of high strength, corrosion resistance, low relaxation and high toughness. Because its added value is greater than that of similar wire products, it is welcomed by the market industry. With the rapid development of the economy and society, the quality requirements of high carbon hard wire products are constantly improving. At present, the minimum specification of high carbon steel wire that can be cold-drawn at home and abroad is about no more than 0.1mm, and the quality requirements for continuous casting billets are extremely high. Only when the quality of continuous casting billets is qualified can the steel wire be guaranteed not to break during cold drawing and stranding. This puts forward high requirements on the steelmaking process and the level and stability of continuous casting technology.

[0003] Although some scholars have conducted a series of research on this product, they mainly focus on product quality defect analysis and related control process technology research. For example, the patent CN201710914175 discloses a high-carbon wire rod steel production process, CN109207837 discloses a method for producing SWRH82B wire rods, CN103667581 discloses a low-nitrogen SWRH82B steel smelting method, CN108998626 discloses a method for controlling inclusions in the production of SWRH82B steel using a carbon-free ladle, and CN10164821 discloses a prestressed steel SWRH82B large square billet continuous casting dynamic light reduction process. However, in the above-mentioned processes for the preparation of SWRH82B, the improvement of the production process of the continuous casting billet is not involved. However, the current production process of high-carbon hard wire steel continuous casting billets needs to be improved, and the quality stability of continuous casting billets is not high. In addition, with the proposal of domestic dual-carbon goals and the advancement of efficient continuous casting technology, high-carbon hard wire steel also shows great development needs in terms of energy conservation and emission reduction, cost reduction and efficiency improvement. However, it is more difficult to control the central defects of the billet when increasing the casting speed and casting molten steel at a high casting speed. How to produce high-carbon hard wire steel with high-speed continuous casting technology while ensuring that the continuous casting billet meets the subsequent processing requirements and the equipment operates stably has become a more prominent process and technical problem at present.

[0004] Therefore, how to find a more suitable high-carbon hard wire steel continuous casting billet production process, especially a high-speed casting process, to solve the above-mentioned technical problems existing in the existing process has become one of the urgent problems to be solved by many front-line researchers in the industry. Summary of the invention

[0005] In view of this, the technical problem to be solved by the present invention is to provide a high-drawing speed production process and application of high-carbon hard wire steel continuous casting billets, in particular, a high-drawing speed production process of 200mm×200mm continuous casting billets of high-carbon hard wire steel. The production process provided by the present invention can realize the high-drawing speed production of 200mm×200mm continuous casting billets, and the continuous casting billets produced have no obvious defects at low magnification, and the central segregation ratio is lower than 1.10, which can reduce production costs and improve product quality; and the process flow is simple, controllable, and stable, which is more suitable for industrial promotion and application.

[0006] The present invention provides a high-speed drawing production process for high-carbon hard wire steel continuous casting billet, comprising the following steps:

[0007] The molten steel in the ladle is poured into the tundish for ladle replacement, and then poured from the tundish into the crystallizer of the continuous casting machine. Under the pulling speed of the continuous casting machine, after cooling in the secondary cooling zone and the air cooling zone, a continuous casting square billet with a cross-sectional size of 200mm×200mm is obtained;

[0008] The casting speed of the continuous casting machine is 1.5-2.5 m / min;

[0009] The secondary cooling water volume of the secondary cooling zone is 0.6 to 0.9 L / kg.

[0010] Preferably, the molten steel is obtained by sequentially subjecting semi-steel to converter semi-steel smelting, LF refining and RH vacuum treatment;

[0011] The high carbon hard wire steel includes SWRH82B steel or 70 steel;

[0012] The C content of the SWRH82B steel is 0.79% to 0.86%;

[0013] The C content of the 70 steel is 0.67% to 0.75%.

[0014] Preferably, the molten steel casting superheat of the molten steel is 25-35°C;

[0015] The weight of the molten steel in the tundish is greater than or equal to 80% of the tonnage of the tundish;

[0016] During the ladle changing process, the temperature drop of the molten steel in the tundish of the same batch is less than 12°C.

[0017] Preferably, the crystallizer is an electromagnetic stirring crystallizer;

[0018] The stirring current in the crystallizer is 350-450A;

[0019] The stirring frequency of the crystallizer is 3 to 6 Hz.

[0020] Preferably, the secondary cooling zone includes secondary cooling zone 1, secondary cooling zone 2, secondary cooling zone 3 and secondary cooling zone 4;

[0021] The secondary cooling zone adopts the terminal strong cooling method.

[0022] Preferably, the total water volume of the secondary cooling zone is 301.8 to 596.8 L / min;

[0023] The terminal strong cooling is specifically that the water volume in the terminal zone of the secondary cooling zone accounts for 20-30% of the total water volume in the secondary cooling zone;

[0024] The final zone is specifically the secondary cooling zone 4.

[0025] Preferably, the water volume of the secondary cooling zone 1 is 99.8 to 171.9 L / min;

[0026] The amount of water in the secondary cooling zone 1 increases with the increase of the pulling speed;

[0027] The water volume of the secondary cooling zone 2 is 75.4-155.3 L / min;

[0028] The amount of water in the secondary cooling zone 2 increases with the increase of the pulling speed.

[0029] Preferably, the water volume of the secondary cooling zone 3 is 52.2-118.2 L / min;

[0030] The amount of water in the secondary cooling zone 3 increases with the increase of the pulling speed;

[0031] The water volume of the secondary cooling zone 4 is 74.6-151.4 L / min;

[0032] The amount of water in the secondary cooling zone 4 increases with the increase of the pulling speed.

[0033] Preferably, the air cooling zone adopts a strong stirring method;

[0034] The final stirring is arranged at 20% to 30% of the length of the liquid core of the casting;

[0035] The stirring current of the strong final stirring is 300-400A;

[0036] The stirring current frequency of the strong final stirring is 5 to 8 Hz.

[0037] The present invention also provides the use of high-carbon hard wire steel continuous casting billets produced by the high-drawing speed production process described in any one of the above technical solutions in the preparation of wire rod steel.

[0038] The present invention provides a high-speed drawing production process for high-carbon hard wire steel continuous casting billets, comprising the following steps: pouring the molten steel in the ladle into the tundish for ladle replacement, and then pouring the molten steel from the tundish into the crystallizer of the continuous casting machine, and obtaining a continuous casting square billet with a cross-sectional size of 200mm×200mm after cooling in the secondary cooling zone and the air cooling zone under the pulling speed of the continuous casting machine; the pulling speed of the continuous casting machine is 1.5-2.5m / min; the secondary cooling water ratio of the secondary cooling zone is 0.6-0.9L / kg. Compared with the prior art, the present invention specially designs a high-speed drawing production process for high-carbon hard wire steel 200mm×200mm continuous casting billet with specific control parameters, by controlling the parameters of the molten steel discharged from the converter smelting, LF refining and RH vacuum treatment parameters, and then combining specific casting control, especially the control process and parameters of the crystallizer and cooling, thereby preparing a high-quality 200mm×200mm continuous casting billet, which further reflects the high efficiency of continuous casting and the advantages of regulating and controlling the organizational properties. The present invention realizes the high-drawing speed production of 200mm×200mm continuous casting billets of high-carbon hard wire steel. Through the innovative and scientific regulation of the continuous casting equipment process, high-quality continuous casting billets are formed, which lays an important billet quality foundation for the drawing production of products such as wire rod rolling and steel strands. Moreover, the high-drawing speed production process effectively improves production efficiency, reduces production costs, improves product quality, and achieves cost reduction and efficiency improvement. At the same time, the process flow is simple, controllable, and stable, and is more suitable for industrial promotion and application.

[0039] Experimental results show that the preparation method provided by the present invention can successfully achieve high-speed drawing production of 200mm×200mm continuous casting billets of high-carbon hard wire steel, the billet has good low-magnification quality, the continuous casting billet produced has no obvious defects at low magnification, the billet center segregation index is low, the center segregation ratio is lower than 1.10, and the center C segregation index is reduced from 1.15 to 1.30 under the ordinary process to 1.03 to 1.08 under the technology of the present invention, which can reduce production costs and improve product quality. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 This is a low-magnification image of a high-carbon hard wire steel ingot prepared in Example 1 of the present invention;

[0041] Figure 2 This is a low-magnification image of a high-carbon hard wire steel ingot prepared in Example 2 of the present invention;

[0042] Figure 3 This is a low-magnification image of a high-carbon hard wire steel ingot prepared in Example 3 of the present invention;

[0043] Figure 4The C segregation degree at the center of the ingot prepared by the preparation process provided by the present invention is compared with that prepared by the original continuous casting process. DETAILED DESCRIPTION

[0044] In order to further understand the present invention, preferred embodiments of the present invention are described below in conjunction with examples, but it should be understood that these descriptions are only for further illustrating the features and advantages of the present invention rather than limiting the patent claims of the present invention.

[0045] All raw materials of the present invention have no particular limitation on their sources, and can be purchased from the market or prepared according to conventional methods known to those skilled in the art.

[0046] There is no particular limitation on the purity of all raw materials in the present invention. The present invention preferably uses industrial pure steel or high carbon hard wire steel of conventional purity in the casting field.

[0047] The brands and abbreviations of all raw materials of the present invention are conventional brands and abbreviations in the art. Each brand and abbreviation is clear and definite in the field of its related use. Those skilled in the art can purchase them from the market or prepare them by conventional methods according to the brands, abbreviations and corresponding uses.

[0048] The present invention provides a high-speed drawing production process for high-carbon hard wire steel continuous casting billet, comprising the following steps:

[0049] The molten steel in the ladle is poured into the tundish for ladle replacement, and then poured from the tundish into the crystallizer of the continuous casting machine. Under the pulling speed of the continuous casting machine, after cooling in the secondary cooling zone and the air cooling zone, a continuous casting square billet with a cross-sectional size of 200mm×200mm is obtained;

[0050] The casting speed of the continuous casting machine is 1.5-2.5 m / min;

[0051] The secondary cooling water volume of the secondary cooling zone is 0.6 to 0.9 L / kg.

[0052] In the present invention, the casting speed of the continuous casting machine is 1.5-2.5 m / min, can be 1.7-2.3 m / min, can be 1.9-2.1 m / min.

[0053] In the present invention, the secondary cooling specific water volume of the secondary cooling zone is 0.6 to 0.9 L / kg, may be 0.65 to 0.85 L / kg, or may be 0.7 to 0.8 L / kg.

[0054] In the present invention, the molten steel is preferably obtained by sequentially subjecting semi-steel to converter semi-steel smelting, LF refining and RH vacuum treatment.

[0055] In the present invention, the high carbon hard wire steel preferably includes SWRH82B steel or 70 steel.

[0056] See Table 1, which shows the steel composition (mass percentage %) of high carbon hard wire steel SWRH82B.

[0057] Table 1

[0058] C Si Mn P S Cu Fe other 0.79～0.86 0.15～0.35 0.6～0.9 ≤0.03 ≤0.03 ≤0.20 margin National Standard

[0059] See Table 2, which shows the steel composition (mass percentage %) of high carbon hard wire steel 70.

[0060] Table 2

[0061] C Si Mn P S Cu Fe other 0.67～0.75 0.17～0.37 0.5～0.8 ≤0.035 ≤0.035 ≤0.25 margin National Standard

[0062] In the present invention, the C content of the SWRH82B steel is preferably 0.79% to 0.86%, more preferably 0.80% to 0.85%, more preferably 0.81% to 0.84%, and more preferably 0.82% to 0.83%.

[0063] In the present invention, the C content of the 70 steel is preferably 0.67% to 0.75%, more preferably 0.68% to 0.74%, more preferably 0.69% to 0.73%, and more preferably 0.70% to 0.72%.

[0064] In the present invention, the molten steel casting superheat of the smelting molten steel is preferably 25-35°C, more preferably 27-33°C, and more preferably 29-31°C.

[0065] In the present invention, the weight of the molten steel in the tundish is greater than or equal to 80% of the tonnage of the tundish;

[0066] In the present invention, during the ladle changing process, the temperature drop of the molten steel in the tundish of the same batch is preferably less than 12°C.

[0067] In the present invention, the crystallizer is preferably an electromagnetically stirred crystallizer.

[0068] In the present invention, the stirring current in the crystallizer is preferably 350-450A, more preferably 370-430A, and more preferably 390-410A.

[0069] In the present invention, the stirring frequency of the crystallizer is preferably 3 to 6 Hz, more preferably 3.5 to 5.5 Hz, and more preferably 4 to 5 Hz.

[0070] In the present invention, the secondary cooling zone preferably includes secondary cooling zone 1, secondary cooling zone 2, secondary cooling zone 3 and secondary cooling zone 4.

[0071] In the present invention, the secondary cooling zone preferably adopts a terminal strong cooling method.

[0072] In the present invention, the total water volume in the secondary cooling zone is preferably 301.8 to 596.8 L / min, more preferably 350 to 550 L / min, and even more preferably 400 to 500 L / min.

[0073] In the present invention, the terminal strong cooling is preferably such that the water volume in the terminal zone of the secondary cooling zone accounts for 20-30% of the total water volume in the secondary cooling zone, more preferably 22-28%, and more preferably 24-26%.

[0074] In the present invention, the final zone is preferably the secondary cooling zone 4.

[0075] In the present invention, the water volume in the secondary cooling zone 1 is preferably 99.8 to 171.9 L / min, more preferably 110 to 160 L / min, more preferably 120 to 150 L / min, and more preferably 130 to 140 L / min.

[0076] In the present invention, the amount of water in the secondary cooling zone 1 is preferably increased as the pulling speed increases.

[0077] In the present invention, the water volume of the secondary cooling zone 2 is preferably 75.4 to 155.3 L / min, more preferably 80 to 140 L / min, and more preferably 100 to 120 L / min.

[0078] In the present invention, the amount of water in the secondary cooling zone 2 is preferably increased as the casting speed increases.

[0079] In the present invention, the water volume of the secondary cooling zone 3 is preferably 52.2 to 118.2 L / min, more preferably 60 to 110 L / min, more preferably 70 to 100 L / min, and more preferably 80 to 90 L / min.

[0080] In the present invention, the amount of water in the secondary cooling zone 3 is preferably increased as the casting speed increases.

[0081] In the present invention, the water volume of the secondary cooling zone 4 is preferably 74.6 to 151.4 L / min, more preferably 90 to 140 L / min, and more preferably 110 to 120 L / min.

[0082] In the present invention, the amount of water in the secondary cooling zone 4 is preferably increased as the casting speed increases.

[0083] In the present invention, the air cooling zone preferably adopts a strong stirring method.

[0084] In the present invention, the final stirring is preferably set at 20% to 30% of the length of the liquid core of the casting billet, more preferably 22% to 28%, more preferably 24% to 26%. Specifically, 20% to 30% refers to 20% to 30% of the liquid core of the casting billet near the end of the casting billet.

[0085] In the present invention, the stirring current of the strong stirring is preferably 300-400A, more preferably 320-380A, and more preferably 340-360A.

[0086] In the present invention, the stirring current frequency of the strong stirring is preferably 5 to 8 Hz, more preferably 5.5 to 7.5 Hz, and more preferably 6 to 7 Hz.

[0087] The present invention provides the use of a high-carbon hard wire steel continuous casting billet produced by the high-drawing speed production process described in any one of the above technical solutions in the preparation of wire rod steel.

[0088] The present invention is to complete and refine the overall technical solution, better ensure the microstructure, composition and performance of the high carbon hard wire steel billet, and further improve the stability and efficiency of the preparation of the high carbon hard wire steel 200mm×200mm continuous casting billet. The high-speed drawing production process and application of the high carbon hard wire steel 200mm×200mm continuous casting billet may specifically include the following contents:

[0089] The invention provides a high-speed drawing production process for high-carbon hard wire steel 200mm×200mm continuous casting billet, and the process technology flow is: converter semi-steel smelting--LF electric heating refining--RH vacuum treatment--200mm×200mm cross-section square billet continuous casting.

[0090] Specific key processes and parameters include: the superheat of molten steel casting is controlled at 25-35℃.

[0091] Specifically, the continuous casting machine has an operating speed of 1.5 to 2.5 m / min.

[0092] Specifically, when changing the ladle, the weight of the molten steel in the tundish shall not be less than 80% of the tonnage of the tundish, and the temperature drop of the molten steel in the tundish of the same batch shall be less than 12°C.

[0093] Specifically, electromagnetic stirring is used in the crystallizer (stirring current: 350-450A, stirring frequency: 3-6Hz); terminal strong cooling is adopted, and the water volume in the final zone (second cooling zone 4) accounts for 20-30% of the total water volume. The water table is shown in Table 3, which is the terminal strong cooling water table.

[0094] Table 3

[0095]

[0096] Specifically, the secondary cooling water volume is 0.6-0.9 L / kg at a pulling speed of 1.5-2.5 m / min; the final stirring device is installed at a position where the proportion of the liquid core of the casting is 20%-30% (stirring current: 300-400 A, stirring frequency: 5-8 Hz).

[0097] In addition to the above key technical points that must be implemented as required, the present invention requires that other continuous casting system processes be implemented in a conventional manner.

[0098] The above content of the present invention provides a high-drawing speed production process and application of a 200mm×200mm continuous casting billet of high-carbon hard wire steel. The high-drawing speed production process of a 200mm×200mm continuous casting billet of high-carbon hard wire steel specially designed by the present invention with specific control parameters controls the parameters of the molten steel discharged from the converter, the LF refining and the RH vacuum treatment parameters, and combines specific casting control, especially the control process and parameters of the crystallizer and cooling, so as to prepare a high-quality 200mm×200mm continuous casting billet, which further reflects the high efficiency of continuous casting and the advantages of regulating the organization and performance. The present invention realizes the high-drawing speed production of 200mm×200mm continuous casting billets of high-carbon hard wire steel, forms high-quality continuous casting billets through innovative and scientific regulation of continuous casting equipment and process, and lays an important billet quality foundation for the drawing production of products such as wire rod rolling and steel strands, and the high-drawing speed production process effectively improves production efficiency, reduces production costs, improves product quality, and achieves cost reduction and efficiency improvement. At the same time, the process flow is simple, controllable, and stable, which is more suitable for industrial promotion and application.

[0099] Experimental results show that the preparation method provided by the present invention can successfully achieve high-speed drawing production of 200mm×200mm continuous casting billets of high-carbon hard wire steel, the billet has good low-magnification quality, the continuous casting billet produced has no obvious defects at low magnification, the billet center segregation index is low, the center segregation ratio is lower than 1.10, and the center C segregation index is reduced from 1.15 to 1.30 under the ordinary process to 1.03 to 1.08 under the technology of the present invention, which can reduce production costs and improve product quality.

[0100] In order to further illustrate the present invention, a high-speed drawing production process and application of a high-carbon hard wire steel continuous casting billet provided by the present invention are described in detail below in combination with the embodiments. However, it should be understood that these embodiments are implemented on the premise of the technical scheme of the present invention, and detailed implementation methods and specific operating procedures are given only to further illustrate the features and advantages of the present invention, rather than to limit the claims of the present invention. The protection scope of the present invention is not limited to the following embodiments.

[0101] Example 1

[0102] The high carbon hard wire steel used in high drawing speed production is SWRH82B steel, and the steel composition is shown in Table 1.

[0103] The process technology flow is: converter semi-steel smelting--LF electric heating refining--RH vacuum treatment--200mm×200mm cross-section square billet continuous casting.

[0104] The cross-section of the ingot is 200mm×200mm, the working pulling speed is 1.5m / min, the average temperature of the molten steel in the tundish is 1498℃, and the temperature of the molten steel in the same furnace drops by about 8℃.

[0105] The crystallizer cooling water flow rate is 10.8m / s, the average heat flux is 1.9MW, the crystallizer free liquid level fluctuation is about ±4mm, the crystallizer electromagnetic stirring current is 396A, and the stirring frequency is 5Hz.

[0106] The surface temperature of the billet at the straightening machine is 979℃, and the end strong cooling water meter at 1.5m / min in Table 3 is used for cooling, and the water volume on the inner arc surface is 120.7L / min. Strong stirring is performed in the air cooling zone, the stirring current is 320A, the stirring frequency is 6Hz, and the stirring installation position is 6.8m. The nail shooting method experiment shows that the liquid core ratio here is 23% of the 200mm×200mm section, which can exert the best stirring effect and produce billet low magnification Figure 1 , there is no central porosity or shrinkage cavity, CET has good neutrality, and the central segregation ratio is 1.04-1.06.

[0107] See also Figure 1 , Figure 1 This is a low-magnification image of the high-carbon hard wire steel ingot prepared in Example 1 of the present invention.

[0108] Example 2

[0109] The steel used in this embodiment is SWRH82B steel, and the steel composition is shown in Table 1.

[0110] The process technology flow is: converter semi-steel smelting--LF electric heating refining--RH vacuum treatment--200mm×200mm cross-section square billet continuous casting.

[0111] The cross-section of the ingot is 200mm×200mm, the working pulling speed is 2.0m / min, the average temperature of the molten steel in the tundish is 1496℃, and the temperature of the molten steel in the same furnace drops by about 10℃.

[0112] The crystallizer cooling water flow rate is 11.4 m / s, the average heat flux is 2.2 MW, the crystallizer free liquid level fluctuation is about 4.3 mm, the crystallizer electromagnetic stirring current is 400 A, and the stirring frequency is 5 Hz.

[0113] The surface temperature of the billet at the straightening machine is 983℃, and the end strong cooling water meter at 2.0m / min in Table 3 is used for cooling. Strong stirring is performed in the air cooling zone, the stirring current is 328A, the stirring frequency is 5Hz, and the stirring installation position is 8.4m. The nail shooting method experiment shows that the liquid core ratio here is 25% of the 200mm×200mm section. The low magnification view of the produced billet Figure 2 There is no obvious central porosity or shrinkage cavity, CET is slightly close to the outer arc side, and the central segregation ratio is 1.06-1.08.

[0114] See also Figure 2 , Figure 2 This is a low-magnification image of the high-carbon hard wire steel ingot prepared in Example 2 of the present invention.

[0115] Example 3

[0116] The steel grade used in this embodiment is 70 steel, and the steel grade composition is shown in Table 2.

[0117] The process technology flow is: converter semi-steel smelting--LF electric heating refining--RH vacuum treatment--200mm×200mm cross-section square billet continuous casting.

[0118] The cross-section of the ingot is 200mm×200mm, the working pulling speed is 2.4m / min, the average temperature of the molten steel in the tundish is 1493℃, and the temperature of the molten steel in the same furnace drops by about 12℃.

[0119] The crystallizer cooling water flow rate is 12.1m / s, the average heat flux is 2.5MW, the crystallizer free liquid level fluctuation is about 4.6mm, the crystallizer electromagnetic stirring current is 410A, and the stirring frequency is 6Hz.

[0120] The surface temperature of the billet at the straightening machine is 988℃, and the end strong cooling water meter at 2.4m / min in Table 3 is used for cooling. Strong stirring is performed in the air cooling zone, the stirring current is 335A, the stirring frequency is 7Hz, and the stirring installation position is 9.6m. The nail shooting method experiment shows that the liquid core ratio here is 28% of the 200mm×200mm section, and the low magnification view of the produced billet is Figure 3 , there is no central porosity or shrinkage cavity, CET has good neutrality, and the central segregation ratio is 1.03~1.08.

[0121] See also Figure 3 , Figure 3 This is a low-magnification image of the high-carbon hard wire steel ingot prepared in Example 3 of the present invention.

[0122] The above implementation examples show that by adopting the present invention, the high-speed production of 200mm×200mm continuous casting billets of high-carbon hard wire steel is successfully achieved, the billet has good low-multiple quality, and the billet center segregation index is low. The specific comparison of the C segregation degree of the billet center before and after actual collection is as follows: Figure 4 As shown, Figure 4 The C segregation degree of the center of the ingot prepared by the preparation process provided by the present invention is compared with that prepared by the original continuous casting process. The high carbon hard wire steel 200mm×200mm continuous casting ingot prepared by the present invention can better meet the microstructure control of wire rod rolling and the requirements of rear-end drawing and stripping processing.

[0123] The above is a detailed introduction to the high-speed production process and application of a high-carbon hard wire steel 200mm×200mm continuous casting billet provided by the present invention. The principle and implementation method of the present invention are explained in detail using specific examples. The description of the above embodiments is only used to help understand the method and core idea of ​​the present invention, including the best mode, and also enables any technician in the field to practice the present invention, including manufacturing and using any device or system, and implementing any combined method. It should be pointed out that for ordinary technicians in this technical field, without departing from the principle of the present invention, the present invention can also be improved and modified in several ways, and these improvements and modifications also fall within the scope of protection of the claims of the present invention. The scope of patent protection of the present invention is defined by the claims and may include other embodiments that can be thought of by those skilled in the art. If these other embodiments have structural elements similar to the literal expression of the claims, or if they include equivalent structural elements that are not substantially different from the literal expression of the claims, then these other embodiments should also be included in the scope of the claims.

Claims

1. A high-speed production process for continuous casting of high-carbon hard wire steel, characterized in that: The following steps are involved: The molten steel in the ladle is poured into the tundish for ladle replacement, and then poured from the tundish into the crystallizer of the continuous casting machine. Under the pulling speed of the continuous casting machine, after cooling in the secondary cooling zone and the air cooling zone, a continuous casting square billet with a cross-sectional size of 200mm×200mm is obtained; The casting speed of the continuous casting machine is 1.5-2.5 m / min; The secondary cooling water volume of the secondary cooling zone is 0.6 to 0.9 L / kg.

2. The high-speed drawing production process according to claim 1, characterized in that: The molten steel is obtained by sequentially subjecting semi-steel to converter semi-steel smelting, LF refining and RH vacuum treatment; The high carbon hard wire steel includes SWRH82B steel or 70 steel; The C content of the SWRH82B steel is 0.79% to 0.86%; The C content of the 70 steel is 0.67% to 0.75%.

3. The high-speed drawing production process according to claim 1, characterized in that: The superheat of the molten steel casting is 25-35°C; The weight of the molten steel in the tundish is greater than or equal to 80% of the tonnage of the tundish; During the ladle changing process, the temperature drop of the molten steel in the tundish of the same batch is less than 12°C.

4. The high-speed drawing production process according to claim 1, characterized in that: The crystallizer is an electromagnetically stirred crystallizer; The stirring current in the crystallizer is 350-450A; The stirring frequency of the crystallizer is 3 to 6 Hz.

5. The high-speed drawing production process according to claim 1, characterized in that: The secondary cooling zone includes secondary cooling zone 1, secondary cooling zone 2, secondary cooling zone 3 and secondary cooling zone 4; The secondary cooling zone adopts the terminal strong cooling method.

6. The high-speed drawing production process according to claim 5, characterized in that: The total water volume of the secondary cooling zone is 301.8 to 596.8 L / min; The terminal strong cooling is specifically that the water volume in the terminal zone of the secondary cooling zone accounts for 20-30% of the total water volume in the secondary cooling zone; The final zone is specifically the secondary cooling zone 4.

7. The high-speed drawing production process according to claim 5, characterized in that: The water volume of the secondary cooling zone 1 is 99.8-171.9 L / min; The amount of water in the secondary cooling zone 1 increases with the increase of the pulling speed; The water volume of the secondary cooling zone 2 is 75.4-155.3 L / min; The amount of water in the secondary cooling zone 2 increases with the increase of the pulling speed.

8. The high-speed drawing production process according to claim 5, characterized in that: The water volume of the secondary cooling zone 3 is 52.2-118.2 L / min; The amount of water in the secondary cooling zone 3 increases with the increase of the pulling speed; The water volume of the secondary cooling zone 4 is 74.6-151.4 L / min; The amount of water in the secondary cooling zone 4 increases with the increase of the pulling speed.

9. The high-speed drawing production process according to claim 1, characterized in that: The air cooling zone adopts a strong stirring method; The final stirring is arranged at 20% to 30% of the length of the liquid core of the casting; The stirring current of the strong final stirring is 300-400A; The stirring current frequency of the strong final stirring is 5 to 8 Hz.

10. Use of the high carbon hard wire steel continuous casting billet produced by the high drawing speed production process according to any one of claims 1 to 9 in the preparation of wire rod steel.

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