Production method for reducing occurrence rate of longitudinal cracks of high-manganese steel plate and high-manganese steel plate

Abstract

The invention discloses a production method for reducing the occurrence rate of longitudinal cracks of a high-manganese steel plate and the high-manganese steel plate. Molten iron is subjected to desulfurization, converter smelting and refining treatment to obtain refined molten steel, and then the refined molten steel is subjected to continuous casting, hot rolling, laminar cooling, coiling and decoiling treatment to obtain the high-manganese steel plate. Wherein the refined molten steel comprises, by mass, 0.12%-0.14% of As and 0.13%-0.15% of Cu, and the hydrogen content in the refined molten steel is controlled to be 6 ppm to 10 ppm, so that the occurrence rate of longitudinal cracks of the high-manganese steel plate can be reduced to 0.5% or below, and the defect that the high-manganese steel plate has many longitudinal cracks is obviously overcome.

Description

Technical Field

[0001] The present application belongs to the field of metal material processing, and in particular relates to a production method for reducing the incidence of longitudinal cracks in high manganese steel plates and a high manganese steel plate. Background Art

[0002] High manganese steel is a special alloy steel with excellent wear resistance and corrosion resistance, and is widely used in mining, cement, building materials, metallurgy and other industries. However, in the process of producing high manganese steel plates using the existing refined steel composition design and preparation process, the probability of subsurface longitudinal cracks in the ingot is high, which leads to the problem of many longitudinal cracks in the high manganese steel plates obtained by hot continuous rolling. Summary of the invention

[0003] The embodiments of the present application provide a production method and a high manganese steel plate for reducing the incidence of longitudinal cracks in high manganese steel plates, which can improve the defects of high manganese steel plates with many longitudinal cracks and high incidence.

[0004] In the first aspect, an embodiment of the present application provides a production method for reducing the incidence rate of longitudinal cracks in high manganese steel plates, comprising: desulfurizing, converter smelting and refining molten iron to obtain refined molten steel, wherein the hydrogen content in the refined molten steel is 6ppm-10ppm; the refined molten steel contains, by mass percentage, As: 0.12%-0.14%, Cu: 0.13%-0.15%, C: 0.80%-1.30%, Si: 0.30%-0.60%, Mn: 12.0%-15.0%, P: ≤0.035%, S: ≤0.020%, Als: 0.006%-0.050%, and the rest are Fe and inevitable impurity elements in raw materials; the refined molten steel is continuously cast, hot rolled, laminar cooled, coiled and flattened to obtain a high manganese steel plate.

[0005] According to an embodiment of the first aspect of the present application, the present invention comprises: desulfurizing, converter smelting and refining molten iron to obtain refined molten steel, wherein the hydrogen content in the refined molten steel is 7ppm; the refined molten steel contains, by mass percentage, As: 0.13%, Cu: 0.14%, C: 0.80%-1.30%, Si: 0.30%-0.60%, Mn: 12.0%-15.0%, P: ≤0.035%, S: ≤0.020%, Als: 0.006%-0.050%, and the rest are Fe and inevitable impurity elements in the raw materials; the refined molten steel is continuously cast, hot rolled, laminar cooled, coiled and flattened to obtain a high manganese steel plate.

[0006] According to the embodiment of the first aspect of the present application, the step of continuous casting of refined molten steel includes: injecting the refined molten steel into a tundish, pouring the tundish molten steel into a crystallizer, and performing continuous casting to obtain a cast billet; wherein the superheat of the molten steel in the tundish during pouring is 5°C-25°C, and the pulling speed during continuous casting is 3.0m / min-3.5m / min.

[0007] According to an embodiment of the first aspect of the present application, the continuous casting process further includes primary cooling and secondary cooling, and the specific water volume of the secondary cooling is 1.0L / kg-1.2L / kg.

[0008] According to an embodiment of the first aspect of the present application, the melting point of the protective slag in the crystallizer is 780°C-850°C; and / or the basicity of the protective slag is 0.9-1.1; and / or, based on the total mass of the protective slag, the mass fraction of lithium oxide in the protective slag is 4.0%-5.0%.

[0009] According to the embodiment of the first aspect of the present application, the vibration mode of the crystallizer is non-sinusoidal vibration; wherein the vibration frequency of the non-sinusoidal vibration is 260 times / min-280 times / min, the amplitude is 4.4mm-4.8mm, and the deflection rate is 18%.

[0010] According to the embodiment of the first aspect of the present application, in the process of obtaining high manganese steel plate by continuous casting, hot rolling, laminar cooling, coiling and flattening of refined molten steel, the hot rolling process includes heating, rough rolling, finish rolling and coiling of the ingot; wherein, the furnace discharge temperature of the ingot in the hot rolling process is 1260-1300°C, the final rolling temperature of the finish rolling is 900°C-960°C, and the coiling temperature is 80°C~200°C.

[0011] According to the embodiment of the first aspect of the present application, the thickness of the ingot is 55mm-65mm; the thickness of the high manganese steel plate is 1.2mm-6.0mm.

[0012] In a second aspect, the present application provides a high manganese steel plate, which is prepared according to the above production method, and the longitudinal crack incidence rate of the high manganese steel plate is less than 0.5%.

[0013] According to an embodiment of the second aspect of the present application, the hydrogen content in the high manganese steel plate is 6ppm-10ppm, and the high manganese steel plate contains As: 0.12%-0.14%, Cu: 0.13%-0.15%, C: 0.80%-1.30%, Si: 0.30%-0.60%, Mn: 12.0%-15.0%, P: ≤0.035%, S: ≤0.020%, Als: 0.006%-0.050%, and the rest are Fe and unavoidable impurity elements in raw materials.

[0014] The production method for reducing the incidence of longitudinal cracks in high manganese steel plates in the embodiment of the present application is to obtain refined molten steel by desulfurizing, converter smelting and refining molten iron, and then to obtain high manganese steel plates by continuous casting, hot rolling, laminar cooling, coiling and unwinding the refined molten steel. Among them, the refined molten steel contains As: 0.12%-0.14%, Cu: 0.13%-0.15% by mass percentage, and by controlling the hydrogen content in the refined molten steel to 6ppm-10ppm, the incidence of longitudinal cracks in high manganese steel plates can be reduced to less than 0.5%, significantly improving the defect of many longitudinal cracks in high manganese steel plates, and at the same time, the thickness of the steel plate can be greatly reduced, reducing its thickness to 1.2mm-6.0mm. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] In order to more clearly illustrate the technical solution of the embodiments of the present application, the following is a brief introduction to the drawings required for use in the embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0016] Figure 1 This is a schematic diagram of a finished high manganese steel plate of Example 1 of the present application;

[0017] Figure 2 This is a schematic diagram of the finished high manganese steel plate of comparative example 1 of the present application. DETAILED DESCRIPTION

[0018] In order to make the application purpose, technical solution and beneficial technical effect of this application clearer, the application is further described in detail below in conjunction with the embodiments. It should be understood that the implementation regulations described in this specification are only for explaining this application, not for limiting this application.

[0019] For simplicity, the present application only explicitly discloses some numerical ranges. However, any lower limit can be combined with any upper limit to form an unclearly recorded range; and any lower limit can be combined with other lower limits to form an unclearly recorded range, and any upper limit can be combined with any other upper limit to form an unclearly recorded range. In addition, although not clearly recorded, each point or single value between the range endpoints is included in the range. Thus, each point or single value can be combined with any other point or single value as its own lower limit or upper limit or with other lower limits or upper limits to form an unclearly recorded range.

[0020] It should be noted that the terms "include", "comprises" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the sentence "includes..." do not exclude the existence of other identical elements in the process, method, article or device including the elements.

[0021] Unless otherwise specified, the values ​​of the parameters mentioned in this application can be measured by various measurement methods commonly used in the art (for example, they can be tested according to the methods given in the examples of this application). Unless otherwise specified, the test temperature of the parameters mentioned in this application is 25° C. and the test pressure is standard atmospheric pressure.

[0022] The above application content of the present application is not intended to describe each disclosed embodiment or each implementation in the present application. The following description more specifically illustrates exemplary embodiments. In many places throughout the application, guidance is provided through a series of embodiments, and these implementation regulations can be used in various combinations. In each example, enumeration is only used as a representative group and should not be interpreted as exhaustive.

[0023] The following is a detailed description of the chemical components in the examples of this application:

[0024] C: C is one of the most effective elements for solid solution strengthening and is also the most effective element for ensuring austenite stabilization. However, an increase in C content will also increase the difficulty of continuous casting production, resulting in excessive precipitation of cast carbides, reducing the plasticity of the ingot, and causing cracks to form on the surface of the continuous casting ingot. On the other hand, an increase in C content will deteriorate the welding and bending properties of the material. Therefore, in order to ensure the strength and austenite structure of the steel plate while taking into account the production, processing and application of the material, the C content of the steel plate is controlled at 0.80%-1.30%.

[0025] Si: When the Si content in steel reaches about 1%, heat-resistant steel can form a protective dense oxide layer on the surface of the steel plate under long-term high-temperature service conditions, thereby improving the high-temperature oxidation resistance of heat-resistant steel. In addition, Si is also an alloy element with strong solid solution strengthening, so the Si content is controlled at 0.30%-0.60%.

[0026] Mn: Manganese is an austenite-forming element. A higher Mn content ensures that the material structure is austenite, thereby ensuring that the material still has extremely low magnetic permeability under high magnetic field strength. At the same time, the large amount of Mn added causes the austenite structure to undergo twin transformation during the strain process, thereby playing a role in fine grain strengthening and improving the plasticity and toughness of the material. In addition, the addition of Mn can reduce the density of steel and achieve lightweight applications, so the Mn content is controlled at 12.0%-15.0%.

[0027] P and S: P and S are harmful inclusions in steel, which have a great damaging effect on the steel's formability, low-temperature toughness, weldability and fatigue performance. In order to reduce production costs and improve product quality, this application controls the P content below 0.035% and the S content below 0.020%, so that the influence of P and S on the formability is reduced to the lowest possible level.

[0028] Als: Als has a deoxidizing effect in the steelmaking process and can improve the purity of molten steel. Therefore, the Als content in this application is limited to 0.006%-0.050%.

[0029] Cu: Cu acts as an active cathode, and under certain conditions, it can promote the anodic passivation of steel, thereby reducing the corrosion rate of steel; another view is that the combined action of Cu and P promotes the formation of extremely dense amorphous Fe3O4 in the rust layer, thereby preventing oxygen and water from penetrating into the steel matrix, and Cu can also react with S to form insoluble compounds to block the cracks in the rust layer; when steel contains too much Cu, it will affect the welding performance of the steel. Adding too much Cu leads to problems such as decreased welding performance of steel, increased porosity, and enhanced thermal crack sensitivity, so the present invention designs the Cu content to be 0.13%-0.15%.

[0030] As: As can improve the tensile strength and yield point of steel, and enhance its corrosion resistance and oxidation resistance. However, when the As content is high (e.g., greater than 0.2%), small cracks and brittle fractures will appear on the grain boundaries and fracture surfaces in the steel, thereby reducing the toughness and plasticity of the steel, causing the steel to be easily cracked, deformed, and brittle. Therefore, the present invention designs the As content to be 0.12%-0.14%.

[0031] There are three main problems in the production of high-carbon and high-manganese austenitic steels MN12 and MN13 using CSP thin slab continuous casting: 1) The high-temperature linear expansion coefficient of steel is large, which is 1.5-2.0 times that of ordinary steel grades. If the solidification and cooling process of the casting is not properly controlled, stress concentration and cracks are easily generated; 2) The carbon content (0.95%) and manganese content (12.5%) in the steel are high, and the liquidus temperature is only about 1400℃, which is 100℃ lower than that of normal steel grades. Only low-melting-point protective slag can be used, otherwise it is easy to cause bonding and steel leakage accidents. , but the melting point of the protective slag is too low to control the longitudinal cracks of the slab; 3) In the smelting process of high manganese steel, Cu and other residual elements (such as Zn, Sn, Pb, etc.) in the molten steel are prone to grain boundary segregation. These elements form low-melting copper-containing alloys in the grain boundary area. The enrichment of low-melting copper alloys at the grain boundary and phase boundary will induce cracks in the steel plate. The higher the Cu content in the steel, the more obvious the segregation of Cu at the grain boundary, and the higher the frequency of cracks. Similarly, the enrichment of As elements at the grain boundary is another important cause of surface cracks on the hot-rolled plate. Due to the above reasons, the longitudinal crack problem is serious during the CSP thin slab continuous casting production of MN13, resulting in a large number of scrapped. The inventor unexpectedly found that controlling the H content in the molten steel within a specific range and combining Cu and As elements in a specific ratio can play a significant synergistic role and effectively reduce the incidence of longitudinal cracks in the high manganese steel plate. At the same time, the thickness of the prepared high manganese steel plate can reach 1.2 mm at the thinnest, breaking through the thinnest thickness of the existing high manganese steel plate.

[0032] The embodiments of the present application provide a production method and a high manganese steel plate for reducing the incidence of longitudinal cracks in a high manganese steel plate.

[0033] The embodiment of the present application provides a production method for reducing the incidence of longitudinal cracks in a high manganese steel plate, comprising: desulfurizing, converter smelting and refining molten iron to obtain refined molten steel, wherein the hydrogen content in the refined molten steel is 6ppm-10ppm; the refined molten steel contains, by mass percentage, As: 0.12%-0.14%, Cu: 0.13%-0.15%, C: 0.80%-1.30%, Si: 0.30%-0.60%, Mn: 12.0%-15.0%, P: ≤0.035%, S: ≤0.020%, Als: 0.006%-0.050%, and the rest are Fe and inevitable impurity elements in raw materials; the refined molten steel is continuously cast, hot rolled, laminar cooled, coiled and flattened to obtain a high manganese steel plate.

[0034] Illustratively, the hydrogen content in the refined molten steel may be 6 ppm, 6.5 ppm, 7 ppm, 7.5 ppm, 8 ppm, 8.5 ppm, 9 ppm, 9.5 ppm, or 10 ppm.

[0035] Preferably, the hydrogen content in the refined molten steel is 6.5ppm-9.5ppm.

[0036] More preferably, the hydrogen content in the refined molten steel is 6.5 ppm-8.5 ppm.

[0037] Particularly preferably, the hydrogen content in the refined molten steel is 7 ppm.

[0038] According to the embodiments of the present application, the refined molten steel within the above hydrogen content range can prevent the heat flow of the crystallizer from being too high, which may cause longitudinal cracks in the ingot. At the same time, if the hydrogen in the molten steel cannot escape in time during cooling but accumulates in the structure, it will form high-pressure fine pores, causing the plasticity, toughness and fatigue strength of the steel to drop sharply, and even cause cracks and brittle fractures. Therefore, the hydrogen content in the refined molten steel needs to be controlled below 10ppm.

[0039] Illustratively, the mass percentage of As in the refined molten steel may be 0.12%, 0.125%, 0.13%, 0.135%, or 0.14%.

[0040] Preferably, the mass percentage of As in the refined molten steel is 0.125%-0.135%.

[0041] Illustratively, the mass percentage of Cu in the refined molten steel may be 0.13%, 0.135%, 0.14%, 0.145%, or 0.15%.

[0042] Preferably, the mass percentage of Cu in the refined molten steel is 0.135%-0.145%.

[0043] In some optional embodiments, a production method for reducing the incidence of longitudinal cracks in high manganese steel plates comprises: desulfurizing, converter smelting and refining molten iron to obtain refined molten steel, wherein the hydrogen content in the refined molten steel is 7 ppm; the refined molten steel contains, by mass percentage, As: 0.13%, Cu: 0.14%, C: 0.80%-1.30%, Si: 0.30%-0.60%, Mn: 12.0%-15.0%, P: ≤0.035%, S: ≤0.020%, Als: 0.006%-0.050%, and the rest are Fe and inevitable impurity elements in raw materials; the refined molten steel is continuously cast, hot rolled, laminar cooled, coiled and flattened to obtain a high manganese steel plate.

[0044] In the embodiment of the present application, by controlling the mass percentage of each element in the refined molten steel, especially controlling the mass percentage of the As element in the refined molten steel to 0.12%-0.14%, the mass percentage of the Cu element to 0.13%-0.15%, and controlling the hydrogen content in the refined molten steel to be within the range of 6ppm-10ppm, the As element and the Cu element in the above-mentioned specific content ratio can play a synergistic role and can greatly reduce the incidence of longitudinal cracks in the high manganese steel plate. At the same time, the thickness of the prepared high manganese steel plate can reach as thin as 1.2mm, breaking through the thinnest thickness of the existing high manganese steel plate.

[0045] In some optional embodiments, the step of continuously casting the refined molten steel includes: injecting the refined molten steel into a tundish, pouring the molten steel from the tundish into a crystallizer, and continuously casting to obtain a cast billet; wherein, the superheat of the molten steel in the tundish during pouring is 5°C-25°C, and the pulling speed during continuous casting is 3.0m / min-3.5m / min.

[0046] According to the embodiments of the present application, the above-mentioned low superheat pouring can not only achieve high pulling speed, but also reduce leakage accidents, improve the internal and external quality of the ingot, but also reduce the steel tapping temperature and increase the service life of the furnace lining.

[0047] In some optional embodiments, the continuous casting process further includes primary cooling and secondary cooling, and the specific water volume of the secondary cooling is 1.0L / kg-1.2L / kg.

[0048] Exemplarily, the specific water volume of the secondary cooling may be 1.0 L / kg, 1.06 L / kg, 1.0 L / kg, 1.15 L / kg or 1.2 L / kg, or any combination range of the above values.

[0049] According to the embodiments of the present application, the specific water amount will affect the surface temperature distribution, cracks and segregation of the ingot in the secondary cooling zone. The specific water amount within the range of 1.0-1.2L / kg can shorten the ingot casting time, increase the ingot casting speed, reduce the production cost, and ensure that the obtained ingot will not produce longitudinal cracks and the center segregation is relatively slight.

[0050] In some optional embodiments, the melting point of the protective slag in the crystallizer is 780°C-850°C; and / or the basicity of the protective slag is 0.9-1.1; and / or, based on the total mass of the protective slag, the mass fraction of lithium oxide in the protective slag is 4.0%-5.0%.

[0051] According to the embodiments of the present application, the use of a crystallizer protective slag with a melting point of 780°C-850°C can prevent the ingot from sticking and leaking steel, and is beneficial to controlling the generation of longitudinal cracks in the ingot, and the protective slag can have good lubrication and heat transfer functions during high-speed continuous casting; the basicity of the protective slag is in the range of 0.9-1.1, and the protective slag has a strong ability to absorb inclusions. At the same time, after absorbing a small amount of Al2O3, the performance of the protective slag remains stable, and smooth production and the surface quality of the ingot are guaranteed; lithium oxide with a mass fraction in the range of 4.0%-5.0% can improve the glass properties of the protective slag and make the stability of the protective slag more stable.

[0052] In some optional embodiments, the vibration mode of the crystallizer is non-sinusoidal vibration; wherein the vibration frequency of the non-sinusoidal vibration is 260 times / min-280 times / min, the amplitude is 4.4mm-4.8mm, and the deflection rate is 18%.

[0053] According to the embodiments of the present application, the vibration mode of the crystallizer in the present application is non-sinusoidal vibration, that is, the upward vibration time of the crystallizer is greater than the downward vibration time, which reduces the relative movement speed between the ingot and the upward vibration of the crystallizer. In the present application, the vibration frequency, amplitude and deflection rate of the non-sinusoidal vibration are controlled within the above ranges, which can reduce the possibility of steel leakage caused by adhesion between the ingot shell and the crystallizer wall at high pulling speed.

[0054] In some optional embodiments, in the process of obtaining high manganese steel plate by continuous casting, hot rolling, laminar cooling, coiling and flattening of refined molten steel, the hot rolling process includes heating, rough rolling, finish rolling and coiling of the ingot; wherein, the furnace discharge temperature of the ingot in the hot rolling process is 1260℃-1300℃, the final rolling temperature of the finish rolling is 900℃-960℃, and the coiling temperature is 80℃~200℃.

[0055] Illustratively, the furnace tapping temperatures of the cast slabs in the hot rolling process are 1260°C, 1270°C, 1280°C, 1290°C, and 1300°C.

[0056] Illustratively, the final rolling temperature of the finish rolling is 900°C, 910°C, 920°C, 930°C, 940°C, 950°C, or 960°C.

[0057] Exemplarily, the coiling temperature is 80°C, 90°C, 100°C, 110°C, 120°C, 130°C, 140°C, 150°C, 160°C, 170°C, 180°C, 190°C, or 200°C.

[0058] According to the embodiments of the present application, the present application controls the hot rolling furnace temperature to 1260°C-1300°C. The higher heating furnace temperature can oxidize the subcutaneous cracks on the surface of the slab into oxides, which can be removed by high-pressure water descaling.

[0059] In some optional embodiments, during the flattening process, the temperature of the steel strip is ≤100°C, preferably 50-100°C.

[0060] Exemplarily, the temperature of the steel strip is 50°C, 60°C, 70°C, 80°C, 90°C, or 100°C.

[0061] In some optional embodiments, the thickness of the ingot is 55 mm-65 mm; the thickness of the high manganese steel plate is 1.2 mm-6.0 mm.

[0062] Illustratively, the thickness of the ingot may be 55 mm, 56 mm, 57 mm, 58 mm, 59 mm, 60 mm, 61 mm, 62 mm, 63 mm, 64 mm or 65 mm, or any combination range of the above values.

[0063] Exemplarily, the thickness of the high manganese steel plate can be 1.2-6.0 mm. For example, the thickness of the high manganese steel plate can be 1.2 mm, 1.5 mm, 2 mm, 2.6 mm, 3.0 mm, 3.5 mm, 4.0 mm, 5.0 mm or 6.0 mm, or any combination range of the above values.

[0064] Preferably, the thickness of the high manganese steel plate is 1.2-3.0 mm, and more preferably, the thickness of the high manganese steel plate is 1.2-1.4 mm.

[0065] According to the embodiments of the present application, the thickness of the ingot obtained by the above-mentioned production method can reach 55mm-65mm, which is thinner than the thickness of the high manganese steel ingot produced by the conventional method, and can lay a good foundation for obtaining thinner high manganese steel plates in the subsequent steel rolling process; the thickness of the high manganese steel plate made from the above-mentioned ingot can reach 1.2mm at the thinnest, breaking through the thinnest thickness of the existing high manganese steel plates. The high manganese steel plate not only has good mechanical properties, but also has an extremely low incidence of longitudinal cracks.

[0066] The embodiment of the present application provides a high manganese steel plate, which is prepared according to the above production method, and the longitudinal crack incidence rate of the high manganese steel plate is less than 0.5%.

[0067] For example, the longitudinal crack occurrence rate of the high manganese steel plate may be 0%, 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, or any combination range of the above values.

[0068] In some optional embodiments, the hydrogen content in the high manganese steel plate is 6ppm-10ppm, and the high manganese steel plate contains, by mass percentage, As: 0.12%-0.14%, Cu: 0.13%-0.15%, C: 0.80%-1.30%, Si: 0.30%-0.60%, Mn: 12.0%-15.0%, P: ≤0.035%, S: ≤0.020%, Als: 0.006%-0.050%, and the rest are Fe and inevitable impurity elements in the raw materials.

[0069] In some optional embodiments, the high manganese steel plate is selected from high carbon high manganese austenitic steel MN12 and high manganese austenitic steel Mn13, preferably high manganese austenitic steel Mn13.

[0070] Example

[0071] The following examples describe the disclosure of the present application in more detail, and these examples are for illustrative purposes only, as various modifications and variations within the scope of the disclosure of the present application are apparent to those skilled in the art. Unless otherwise stated, all parts, percentages, and ratios reported in the following examples are by mass, and all reagents used in the examples are commercially available or synthesized according to conventional methods and can be used directly without further treatment, and the instruments used in the examples are commercially available.

[0072] Example 1

[0073] A method for preparing a high manganese steel plate, comprising:

[0074] (1) KR desulfurization is performed on molten iron to obtain KR desulfurized molten iron, wherein the KR desulfurized molten iron requires S≤0.005% and a cleanliness ≥90%.

[0075] (2) The molten iron after KR desulfurization is subjected to converter smelting treatment to obtain crude molten steel. During the converter smelting process, the furnace mouth pressure must be guaranteed to be positive to prevent air inhalation, especially in the later stage of blowing. In order to reduce the P content of the final molten steel, a double slag or slag pouring process before steel tapping can be adopted. When tapping, front and rear slag blocking is performed to strictly control the slag discharge. 200-400kg of lime and other slag washing materials are added. High carbon ferromanganese, ferrosilicon, ferroaluminum, etc. are used for deoxidation and alloying.

[0076] (3) The crude steel liquid is subjected to LF refining treatment to obtain refined steel liquid, wherein the LF refining treatment process includes: before LF refining treatment, the refining temperature measuring gun is calibrated at 1400°C and 1450°C; then the electrochemical slag is sent into the station, and the arc is started by low-speed current and the temperature is increased by high-speed current; slag materials such as pre-melted slag, lime, and submerged arc slag are added during the arc starting process, and various slag materials are appropriately added during the power transmission process according to the submerged arc conditions. After power transmission, aluminum is added to about 0.06%, and sampling is performed when the ladle top slag turns green or green-yellow. Aluminum supplementation is prohibited 5 minutes before calcium treatment, and Ca is controlled at 0.0020-0.0050%. The argon gas flow rate during the treatment process is controlled at 200-400NL / min; the refining station outlet temperature = liquidus temperature + (35°C-60°C).

[0077] The hydrogen content in the refined molten steel finally prepared is 7ppm, and the refined molten steel contains As: 0.13%, Cu: 0.14%, C: 0.80%-1.30%, Si: 0.30%-0.60%, Mn: 12.0%-15.0%, P: ≤0.035%, S: ≤0.020%, Als: 0.006%-0.050%, and the rest are Fe and inevitable impurity elements in the raw materials.

[0078] (4) The refined molten steel is subjected to continuous casting, hot rolling, laminar cooling, coiling and flattening treatment to obtain a high manganese steel plate.

[0079] Among them, in the continuous casting process, the superheat of the molten steel in the tundish during pouring is 12°C, and the pulling speed during continuous casting is 3.2m / min; the melting point of the protective slag in the crystallizer is 812°C; the basicity of the protective slag is 0.95; based on the total mass of the protective slag, the mass fraction of lithium oxide in the protective slag is 4.9%; the vibration mode of the crystallizer is non-sinusoidal vibration; among them, the vibration frequency of the non-sinusoidal vibration is 265 times / min, the amplitude is 4.7mm, and the deviation rate is 18%; the specific water volume of secondary cooling is 1.12L / kg.

[0080] In the hot rolling process, the slab temperature out of the furnace is 1290℃, and the time in the furnace is 55min; the atmosphere in the furnace is controlled to maintain a weak oxidizing atmosphere in the heating furnace. The descaling pressure is 200-220bar for the front spray and 300-320bar for the rear spray, so as to remove the iron oxide scale formed on the surface of the slab in the heating furnace and prevent the oxide from being pressed into the surface of the slab during rolling. The water spraying at the roll gap of the F1-F4 stand is ≥25m 3 / h, downward spray ≥30m 3 / h setting; turn off the spray water of the roll gap of F5-F7 stands. The reduction rate of thin gauge stands below 3mm: F1≥45%, F2≥40%, F3≥35%, F4≥30%, F5≥20%, F6≥15%, F7≤15%, inter-stand cooling water: F1, F2, F3 are opened ≥20%, ≥20%, ≥20% respectively, and F4, F5, F6, F7 are not opened. The finishing rolling temperature is 940℃, and the coiling temperature is 150℃.

[0081] During the kaiping process, the temperature of the strip is ≤80℃.

[0082] Comparative Example 1

[0083] The only difference from Example 1 is that the refined molten steel finally prepared contains, by mass percentage, As: 0.0020% (As element is a residual value, the content of which is extremely low and can be ignored), Cu: 0.27%, C: 0.80%-1.30%, Si: 0.30%-0.60%, Mn: 12.0%-15.0%, P: ≤0.035%, S: ≤0.020%, Als: 0.006%-0.050%, and the rest are Fe and inevitable impurity elements in the raw materials.

[0084] Comparative Example 2

[0085] The only difference from Example 1 is that the refined molten steel finally prepared contains, by mass percentage, As: 0.27%, Cu: 0.0050% (Cu element is a residual value, the content of which is extremely low and can be ignored), C: 0.80%-1.30%, Si: 0.30%-0.60%, Mn: 12.0%-15.0%, P: ≤0.035%, S: ≤0.020%, Als: 0.006%-0.050%, and the rest are Fe and inevitable impurity elements in the raw materials.

[0086] Experimental Results

[0087] The high manganese steel plates of Example 1 and Comparative Examples 1-2 were subjected to performance tests including longitudinal crack incidence and steel plate thickness, and the test method was as follows:

[0088] 1. Incidence rate of longitudinal cracks: the total length of longitudinal crack defects detected by the slab surface inspection instrument / total casting length*100%.

[0090] 2. Steel plate thickness: measured in accordance with national standard GB / T 709-2019.

[0091] The test results are shown in Table 1.

[0092]

[0093] It can be seen from the data in Table 1 that in the present invention, by controlling the hydrogen content in the refined molten steel to 7ppm, the mass percentage of Cu in the refined molten steel to 0.14%, and the mass percentage of As in the refined molten steel to 0.13%, the As element and the Cu element in this specific content ratio can play a synergistic role, thereby reducing the longitudinal crack incidence of the high manganese steel plate to 0.21%; reducing the thickness of the high manganese steel plate to 1.2mm;

[0094] In Comparative Example 1, the mass percentage of Cu in the refined molten steel is 0.27%, and the mass percentage of As in the refined molten steel is 0.0020% (the As element is a residual value, and the content is extremely low and can be ignored), and the corresponding longitudinal crack incidence rate of the high manganese steel plate is as high as 1.58%, which is much higher than 0.21% in Example 1 of the present invention; in Comparative Example 2, the mass percentage of Cu in the refined molten steel is 0.0050% (the Cu element is a residual value, and the content is extremely low and can be ignored), and the mass percentage of As in the refined molten steel is 0.27%, and the corresponding longitudinal crack incidence rate of the high manganese steel plate is as high as 1.48%, which is much higher than 0.21% in Example 1 of the present invention, and the thickness of the high manganese steel plate in Comparative Example 2 is 6.0 mm, which is 4.8 mm thicker than the high manganese steel plate in Example 1 of the present invention. Figure 1 and Figure 2 The figures are schematic diagrams of finished high manganese steel plates of Example 1 of the present application and Comparative Example 1 respectively. It can be observed that by adopting the production method of the present application, the length, width and depth of the longitudinal cracks in the steel plates are reduced compared with those in Comparative Example 1. It can be seen that on the basis of the hydrogen content in the refined molten steel being 7ppm, the Cu element with a mass percentage of 0.14% and the As element with a mass percentage of 0.13% in the refined molten steel of the present invention can play a synergistic role and can greatly reduce the incidence rate of longitudinal cracks in the high manganese steel plates and the thickness of the steel plates.

[0095] The above is only a specific implementation method of the present application. Those skilled in the art can clearly understand that for the convenience and simplicity of description, the specific working process described above can refer to the corresponding process in the aforementioned method embodiment, and will not be repeated here. It should be understood that the protection scope of the present application is not limited to this. Any technician familiar with the technical field can easily think of various equivalent modifications or replacements within the technical scope disclosed in the present application, and these modifications or replacements should be included in the protection scope of the present application.

Claims

1. A production method for reducing the incidence of longitudinal cracks in high manganese steel plates, characterized in that: include: Desulfurizing, converter smelting and refining the molten iron to obtain refined molten steel, wherein the hydrogen content in the refined molten steel is 6ppm-10ppm; The refined molten steel contains, by mass percentage, As: 0.12%-0.14%, Cu: 0.13%-0.15%, C: 0.80%-1.30%, Si: 0.30%-0.60%, Mn: 12.0%-15.0%, P: ≤0.035%, S: ≤0.020%, Als: 0.006%-0.050%, and the rest are Fe and inevitable impurity elements in raw materials; The refined molten steel is subjected to continuous casting, hot rolling, laminar cooling, coiling and flattening treatment to obtain a high manganese steel plate.

2. The production method according to claim 1, characterized in that include: Desulfurizing, converter smelting and refining the molten iron to obtain refined molten steel, wherein the hydrogen content in the refined molten steel is 7 ppm; The refined molten steel contains, by mass percentage, As: 0.13%, Cu: 0.14%, C: 0.80%-1.30%, Si: 0.30%-0.60%, Mn: 12.0%-15.0%, P: ≤0.035%, S: ≤0.020%, Als: 0.006%-0.050%, and the rest are Fe and inevitable impurity elements in the raw materials; The refined molten steel is subjected to continuous casting, hot rolling, laminar cooling, coiling and flattening treatment to obtain a high manganese steel plate.

3. The production method according to claim 1, characterized in that The step of continuously casting the refined molten steel comprises: injecting the refined molten steel into a tundish, which pours the molten steel into a crystallizer, and continuously casting to obtain a cast billet; Wherein, the superheat degree of the molten steel in the tundish during the pouring is 5°C-25°C, and the pulling speed during the continuous casting is 3.0m / min-3.5m / min.

4. The production method according to claim 3, characterized in that: The continuous casting process also includes primary cooling and secondary cooling, and the specific water volume of the secondary cooling is 1.0L / kg-1.2L / kg.

5. The production method according to claim 3, characterized in that: The melting point of the protective slag in the crystallizer is 780°C-850°C; and / or, The basicity of the protective slag is 0.9-1.1; and / or, Based on the total mass of the mold slag, the mass fraction of lithium oxide in the mold slag is 4.0%-5.0%.

6. The production method according to claim 3, characterized in that: The vibration mode of the crystallizer is non-sinusoidal vibration; wherein the vibration frequency of the non-sinusoidal vibration is 260 times / min-280 times / min, the amplitude is 4.4mm-4.8mm, and the deflection rate is 18%.

7. The production method according to claim 1, characterized in that: In the process of continuously casting, hot rolling, laminar cooling, coiling and flattening the refined molten steel to obtain the high manganese steel plate, the hot rolling process includes heating, rough rolling, finish rolling and coiling the ingot; Wherein, the furnace discharge temperature of the cast slab in the hot rolling process is 1260°C-1300°C, the final rolling temperature of the finish rolling is 900°C-960°C, and the coiling temperature is 80°C-200°C.

8. The production method according to claim 1, characterized in that: The thickness of the ingot is 55mm-65mm; The thickness of the high manganese steel plate is 1.2 mm-6.0 mm.

9. A high manganese steel plate, characterized in that: The high manganese steel plate is prepared according to the production method according to any one of claims 1 to 8, and the longitudinal crack incidence rate of the high manganese steel plate is less than 0.5%.

10. The high manganese steel plate according to claim 9, characterized in that: The hydrogen content in the high manganese steel plate is 6ppm-10ppm, and the high manganese steel plate contains As: 0.12%-0.14%, Cu: 0.13%-0.15%, C: 0.80%-1.30%, Si: 0.30%-0.60%, Mn: 12.0%-15.0%, P: ≤0.035%, S: ≤0.020%, Als: 0.006%-0.050%, and the rest are Fe and inevitable impurity elements in raw materials.

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