A method for producing a high speed wire

Abstract

The application relates to the technical field of steel production, in particular to a preparation method of high-speed wire rod. The method comprises the following steps: controlling the chemical composition and physical parameters of a protective slag, performing continuous casting on molten steel with a set chemical composition to obtain a casting blank; performing hot charging and hot feeding on the casting blank so that the casting blank has a set temperature; heating the casting blank with the set temperature so that the heated casting blank reaches a target temperature, and then performing rolling to obtain a wire rod. The application solves the technical problem that the existing high-speed wire rod has defects such as large-area pits and heavy skin on the surface.

Description

TECHNICAL FIELD

[0001] The application relates to a high-speed wire rod preparation method. BACKGROUND

[0002] Hot charging and rolling of continuous casting billets is an energy-saving and environment-friendly hot rolling production process, which can effectively reduce production cost and has been widely used in actual production. The hot charging and rolling process refers to that the continuous casting billets are directly transported to a rolling mill and charged into a heating furnace for reheating at a relatively high temperature, and then hot-rolled after being discharged from the furnace. Compared with the conventional continuous casting billet cold charging and rolling process, the hot charging and rolling of continuous casting billets can not only effectively reduce production energy consumption and shorten heating time, but also significantly reduce burning loss, and gradually becomes an important process for continuous casting and hot rolling production.

[0003] However, due to the imperfection of the continuous casting billet hot charging and rolling process, large-area pits and heavy skin defects appear on the surface of the final high-carbon high-speed wire rod. SUMMARY

[0004] The application provides a high-speed wire rod preparation method to solve the technical problem of large-area pits and heavy skin defects on the surface of the existing high-speed wire rod.

[0005] In a first aspect, the application provides a high-speed wire rod preparation method, which comprises:

[0006] casting a molten steel with a set chemical composition by controlling the chemical composition and physical parameters of the protective slag to obtain a casting billet;

[0007] hot charging and hot sending the casting billet to make the casting billet have a set temperature;

[0008] heating the casting billet with the set temperature to make the heated casting billet reach a target temperature, and then rolling to obtain a wire rod.

[0009] Optionally, the chemical composition of the protective slag comprises:

[0010] C, CaO, MgO, SiO2, Al2O3, Na2O, F, H2O; wherein,

[0011] The content of C is 10-20 wt%, the content of CaO is 19-29 wt%, the content of MgO is ≤5 wt%, the content of SiO2 is 27.5-37.5 wt%, the content of Al2O3 is ≤8 wt%, the content of Na2O is 8-14 wt%, the content of F is 3.5-7.5 wt%, and the content of H2O is ≤0.5 wt%.

[0012] Optionally, the basicity R of the protective slag is 0.73-0.83.

[0013] Optionally, the set chemical composition comprises:

[0014] C, Si, Mn, P, S, N, Fe; wherein,

[0015] The content of C is 0.7wt%-1.2wt%, the content of Si is 0.17wt%-0.30wt%, the content of Mn is 0.50wt%-0.90wt%, the content of P is ≤0.020wt%, the content of S is ≤0.020wt%, and the content of N is ≤0.003wt%.

[0016] Optionally, the physical parameters of the protective slag comprise a protective slag melting point, a protective slag melting speed and a protective slag viscosity.

[0017] Optionally, the protective slag melting point is 980℃-1080℃, the protective slag melting speed is 40s-60s, and the protective slag viscosity is 2.5Pa·s-3.5Pa·s.

[0018] Optionally, the set temperature is 450℃-650℃.

[0019] Optionally, the target temperature is 980℃-1030℃.

[0020] Optionally, the method further comprises:

[0021] heating the cast blank with the set temperature at a first set temperature;

[0022] heating the cast blank with the set temperature at a second set temperature, so that the heated cast blank reaches a target temperature, and then rolling to obtain the wire rod.

[0023] Optionally, the first set temperature is 1150℃-1220℃, and the second set temperature is 1130℃-1190℃.

[0024] Compared with the prior art, the above technical solution provided by the embodiments of the present application has the following advantages:

[0025] The preparation method of high-speed wire provided by the embodiment of the application has low average wire breaking rate. Compared with the normal continuous casting-rolling process, the hot charging and hot feeding process can reduce the energy medium consumption of the rolled wire rod and save costs, is conducive to the production organization on site, reduces the inventory of billets, reduces the occupation of funds, can reduce the core-surface temperature difference of the square billet after the high-carbon steel is reheated, improves the uniform deformation degree of the grains in the rolling process, is conducive to reducing the influence of composition segregation, and improves the performance of the wire rod. The technical problems of the existing high-speed wire surface defects such as large-area pits and heavy skin are solved. BRIEF DESCRIPTION OF DRAWINGS

[0026] The accompanying drawings incorporated in and forming a part of the specification, illustrate embodiments consistent with the present application and serve to explain the principles of the application, together with the description.

[0027] In order to more clearly illustrate the technical solutions in the embodiments of the application or the prior art, the accompanying drawings needed to be used in the embodiments or the prior art description will be briefly introduced as follows. Obviously, for those of ordinary skill in the art, other drawings can also be obtained based on these drawings without any creative effort.

[0028] Figure 1 A flowchart of a preparation method of high-speed wire provided by the embodiment of the application. DETAILED DESCRIPTION

[0029] In order to make the purpose, technical scheme and advantages of the embodiments of the application clearer, the technical scheme in the embodiments of the application will be described clearly and completely in combination with the drawings in the embodiments of the application. Obviously, the described embodiments are a part of the embodiments of the application, rather than all the embodiments of the application. Based on the embodiments in the application, all other embodiments obtained by those of ordinary skill in the art without any creative effort fall within the scope of protection of the application.

[0030] Various embodiments of the present application can exist in a range of forms; it should be understood that the description in a range form is merely for the convenience and brevity, and should not be understood as a hard limitation on the scope of the present application; therefore, it should be considered that the range described has been specifically disclosed all possible sub-ranges and single values within the range. For example, it should be considered that the range description from 1 to 6 has specifically disclosed sub-ranges, such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., as well as single numbers within the range, such as 1, 2, 3, 4, 5, and 6, regardless of the range. In addition, whenever a numerical range is indicated in the present application, it refers to any cited number (fraction or integer) within the indicated range.

[0031] In the present application, the orientation words such as "upper" and "lower" are specifically the directions of the drawing surface in the drawings, unless otherwise stated. In addition, in the description of the present application, the terms "include", "contain" and the like mean "include but are not limited to". In the present text, the relational terms such as "first" and "second" are merely used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between the entities or operations. In the present text, "and / or" describes the association between the associated objects, which means that there can be three relationships, for example, A and / or B can represent the cases of A alone, A and B together, and B alone. Where A and B can be singular or plural. In the present text, "one or more" means one or more, and "multiple" means two or more. "At least one", "at least one of the following" or the like means any combination of the items, including any combination of single or multiple items. For example, "at least one of a, b, or c", or "at least one of a, b, and c", can mean a, b, c, a-b (i.e. a and b), a-c, b-c, or a-b-c, where a, b, and c can be single or multiple.

[0032] Unless otherwise specifically stated, the various raw materials, reagents, instruments and equipment used in the present application can be purchased on the market or can be prepared by existing methods.

[0033] In a first aspect, the present application provides a method for preparing high-speed wire rod, please refer to Figure 1 , the method comprises:

[0034] S1, by controlling the chemical composition and physical parameters of the protective slag, the molten steel with a set chemical composition is continuously cast to obtain a casting blank;

[0035] S2, the casting blank is hot charged and hot sent to have a set temperature;

[0036] S3, heating the casting blank with the set temperature to make the heated casting blank reach a target temperature, and then rolling to obtain a wire rod.

[0037] In some embodiments, the chemical composition of the protective slag comprises:

[0038] C, CaO, MgO, SiO2, Al2O3, Na2O, F, H2O, wherein,

[0039] The content of C is 10-20 wt%, the content of CaO is 19-29 wt%, the content of MgO is ≤5 wt%, the content of SiO2 is 27.5-37.5 wt%, the content of Al2O3 is ≤8 wt%, the content of Na2O is 8-14 wt%, the content of F is 3.5-7.5 wt%, and the content of H2O is ≤0.5 wt%.

[0040] The positive effect of controlling the content of C to be 10-20 wt% is that it is beneficial to heat preservation. Specifically, the content of C can be 10 wt%, 12 wt%, 14 wt%, 16 wt%, 18 wt%, 20 wt%, etc.

[0041] The positive effect of controlling the content of CaO to be 19-29 wt% is that controlling the content of CaO can significantly reduce the viscosity of the slag and absorb oxide inclusions in steel, especially Al2O3 and TiO2. If the content of CaO is too high, it will cause the alkalinity of the protective slag to be too high to some extent; if the content of CaO is too low, it will be not conducive to the control of the viscosity of the protective slag to some extent. Specifically, the content of CaO can be 19 wt%, 21 wt%, 23 wt%, 25 wt%, 27 wt%, 29 wt%, etc.

[0042] The positive effect of controlling the content of MgO to be ≤5 wt% is that the addition of MgO can increase the flowability of the slag and improve the slag consumption when the slag has the same viscosity and softening point. In addition, it is very beneficial to improve the chemical stability of the slag by adding an appropriate amount of MgO to the slag. However, the addition of MgO cannot be too high, and too high MgO will make the melting performance of the slag deteriorate. Specifically, the content of MgO can be 5 wt%, 4 wt%, 3 wt%, 2 wt%, 1 wt%, etc.

[0043] The positive effect of controlling the content of SiO2 to be 27.5%-37.5% by weight is that the viscosity of the protective slag can be controlled. If the content of SiO2 is too high, the viscosity will be too large to some extent; if the content of SiO2 is too low, the basicity of the slag will be too large to some extent. Specifically, the content of SiO2 can be 27.5%, 29.5%, 31.5%, 33.5%, 35.5%, 37.5% by weight, etc.

[0044] The positive effect of controlling the content of Al2O3 to be ≤8% by weight is that Al2O3 can increase the viscosity of the steel, but it can reduce the solidification point of the slag, thereby improving the lubrication of the crystallizer. If the content of Al2O3 is too high, the number of aluminum oxide tetrahedrons will increase, the silicate network chain structure will be complicated, the viscosity will increase, and the solidification temperature will increase to some extent. Specifically, the content of Al2O3 can be 8%, 7%, 6%, 5%, 4% by weight, etc.

[0045] The positive effect of controlling the content of Na2O to be 8%-14% by weight is that Na2O belongs to the network external oxide, can destroy the silicate network structure, has the effect of reducing the melting temperature and viscosity in the protective slag, but it has the tendency to promote the crystallization of the molten slag, and if the amount added is too high, zircon will be easily precipitated in the molten slag, which is not conducive to the lubrication of the crystallizer. If the content of Na2O is too low, it will not be conducive to the control of the viscosity of the protective slag to some extent. Specifically, the content of Na2O can be 8%, 10%, 12%, 14% by weight, etc.

[0046] The positive effect of controlling the content of F to be 3.5%-7.5% by weight is that it is conducive to the control of the low viscosity of the protective slag. If the content of F is too high, it will cause serious erosion of the submerged entry nozzle and also cause pollution to some extent; if the content of F is too low, it will not be conducive to the control of the low viscosity of the protective slag to some extent. Specifically, the content of F can be 3.5%, 4.5%, 5.5%, 6.5%, 7.5% by weight, etc.

[0047] The positive effect of controlling the content of H2O to be ≤0.5% by weight is that water (H2O) is a basic and very important index that must be met, and it cannot be used when the water content exceeds the standard. Because it directly affects the melting and use characteristics of the protective slag, it will cause quality problems such as skin porosity of the cast slab, and in severe cases, it will cause hydrogen increase in the steel, leading to the occurrence of leakage. Generally, the water content measured at 105°C should not be more than 0.5% by weight. Specifically, the content of H2O can be 0.5%, 0.4%, 0.3% by weight, etc.

[0048] In some embodiments, the basicity R of the protective slag is 0.73-0.83.

[0049] The "basicity R of the protective slag" represents the weight ratio of CaO to SiO2, and the positive effect of controlling the basicity R of the protective slag to be 0.73-0.83 is that: the basicity R reflects an important index of the ability of the protective slag to absorb inclusions in the molten steel, and also reflects the advantages and disadvantages of the lubricating performance of the protective slag. Generally, the greater the basicity, the greater the ability to absorb inclusions, but the crystallization temperature becomes larger, resulting in deterioration of the heat transfer and lubricating performance. The high-basicity protective slag can improve the speed of dissolving and absorbing inclusions in the steel, but the viscosity of the basic slag changes greatly with temperature. Specifically, the basicity R of the protective slag can be 0.73, 0.75, 0.77, 0.79, 0.81, 0.83, etc.

[0050] In some embodiments, the set chemical composition includes:

[0051] C, Si, Mn, P, S, N, Fe, wherein,

[0052] The content of C is 0.7%-1.2% by weight, the content of Si is 0.17%-0.30% by weight, the content of Mn is 0.50%-0.90% by weight, the content of P is ≤0.020% by weight, the content of S is ≤0.020% by weight, and the content of N is ≤0.003% by weight.

[0053] The scheme is applicable to high-carbon steel. The protective slag for high-carbon steel has good heat insulation performance and low bulk density.

[0054] In some embodiments, the physical parameters of the protective slag include the melting point of the protective slag, the melting speed of the protective slag, and the viscosity of the protective slag.

[0055] The positive effect of controlling the melting point of the protective slag is that the melting point includes the sintering initiation temperature, the softening temperature or called the deformation temperature, the half-ball point temperature, and the flow temperature. In practical applications, the slag material is made into a standard sample with a cone shape of 3x3mm, and the melting point is measured in a microscope. When the sample is heated to a certain temperature at a certain heating rate, the temperature at which the sample changes from a cylindrical shape to a hemispherical shape is called the melting temperature. In continuous casting production, the melting temperature of the protective slag is usually controlled below 1200℃. It is mainly affected by factors such as the composition, basicity, and Al2O3 content of the protective slag. If the melting temperature is too high, the lubricating effect is poor and uneven.

[0056] The positive effect of controlling the melting speed of the protective slag is that the melting speed is usually represented by the time required for a certain mass of sample to completely melt at a certain temperature. The melting speed of the protective slag in the mold is related to the composition and melting temperature of the slag material. It is an important parameter for realizing the formation of a reasonable three-layer structure of the protective slag in the mold. In order to improve the melting uniformity of the protective slag, the composition of the slag material should be adjusted, the powder processing technology should be improved, and pre-melted slag should be used.

[0057] Positive effect of controlling the viscosity of the protective slag: the viscosity is an important index for measuring the lubricating performance of the protective slag. At present, the rotating method is usually used for determination or the viscosity is calculated according to the empirical formula. At present, the viscosity of the protective slag (1300℃) is mostly measured, and the viscosity of the commonly used protective slag (1300℃) is 0.05 Pa·s-0.15 Pa·s. It is controlled by the chemical composition and the temperature, and in production, the flux is mainly used for adjusting. In order to obtain high-quality casting blank and avoid sticking and leakage, the protective slag with appropriate viscosity must be selected.

[0058] In some embodiments, the melting point of the protective slag is 980℃-1080℃, the melting speed of the protective slag is 40s-60s, and the viscosity of the protective slag is 2.5 Pa·s-3.5 Pa·s.

[0059] Positive effect of controlling the melting point of the protective slag to be 980℃-1080℃: it is beneficial to control the surface quality of the casting blank. If the melting point of the protective slag is too high, the lubricating effect will be poor and uneven to some extent; if the melting point of the protective slag is too low, it will be not conducive to controlling the surface quality of the casting blank to some extent. Specifically, the melting point of the protective slag can be 980℃, 1000℃, 1020℃, 1040℃, 1060℃, 1080℃, etc.

[0060] Positive effect of controlling the melting speed of the protective slag to be 40s-60s: it makes the casting blank have good quality. If the melting speed of the protective slag is too high, the molten protective slag layer in the crystallizer is not easy to maintain the unmelted protective slag layer to some extent, the molten slag is exposed to the atmosphere, the protective slag loses the heat preservation effect, and the casting blank is longitudinally cracked; if the melting speed of the protective slag is too low, the molten slag layer is too thin to some extent, which not only makes the slag film uneven, but also causes longitudinal cracks and sticking leakage. Specifically, the melting speed of the protective slag can be 40s, 45s, 50s, 55s, 60s, etc.

[0061] Positive effect of controlling the viscosity of the protective slag to be 2.5 Pa·s-3.5 Pa·s: it is helpful to obtain high-quality casting blank and avoid sticking leakage. If the viscosity of the protective slag is too high, the surface of the casting blank will be rough to some extent; if the viscosity of the protective slag is too low, a large amount of molten slag will flow into the gap, causing uneven slag film, local solidification to slow down, leading to deformation of the solidified shell, causing longitudinal cracks and pulling leakage accidents. Specifically, the viscosity of the protective slag can be 2.5 Pa·s, 3 Pa·s, 3.5 Pa·s, etc.

[0062] In some embodiments, the setting temperature is 450℃-650℃.

[0063] In the embodiments of the present application, the "set temperature" refers to the temperature of the continuously cast slab for hot charging, and the positive effect of setting the temperature of the continuously cast slab for hot charging to 450-650°C is to ensure the surface quality of the continuously cast slab. If the temperature of the continuously cast slab for hot charging is too high, the continuously cast slab will have defects such as large-area pits and heavy scales on the surface to some extent. Specifically, the temperature of the continuously cast slab for hot charging can be 450°C, 480°C, 510°C, 540°C, 570°C, etc.

[0064] In some embodiments, the target temperature is 980-1030°C.

[0065] In the embodiments of the present application, the "target temperature" refers to the temperature of the continuously cast slab after heating, and the positive effect of setting the temperature of the continuously cast slab after heating to 980-1030°C is to eliminate microstructure defects, so that the steel structure is dense and the mechanical properties are improved. Specifically, the temperature of the continuously cast slab for charging can be 980°C, 990°C, 1000°C, 1010°C, 1020°C, 1030°C, etc., and preferably, the target temperature is 1000°C.

[0066] In some embodiments, the heating of the continuously cast slab with the set temperature comprises:

[0067] heating the continuously cast slab with the set temperature at a first set temperature;

[0068] heating the continuously cast slab after the first heating at a second set temperature.

[0069] In the embodiments of the present application, the "first set temperature" refers to the temperature of the heating section in the heating furnace, and the "second set temperature" refers to the temperature of the soaking section in the heating furnace.

[0070] In some embodiments, the first set temperature is 1150-1220°C, and the second set temperature is 1130-1190°C.

[0071] The positive effect of setting the temperature of the heating section to 1150-1220°C is to improve the plasticity of the steel. If the temperature of the heating section is too high, decarburization, burning loss and oxidation will occur to some extent. Specifically, the temperature of the heating section can be 1150°C, 1170°C, 1190°C, 1210°C, etc.

[0072] The positive effect of setting the temperature of the soaking section to 1130-1190°C is to make the internal and external temperatures of the steel uniform, and to reduce the oxidation and burning loss of the steel. Specifically, the temperature of the soaking section can be 1130°C, 1150°C, 1170°C, 1190°C, etc.

[0073] The application will be further described in conjunction with specific examples. It should be understood that these examples are only used to illustrate the application and not used to limit the scope of the application. The experimental methods in the following examples, if no specific conditions are noted, are generally determined according to national standards. If there is no corresponding national standard, the general international standards, conventional conditions, or the conditions suggested by the manufacturer are used.

[0074] According to a typical embodiment of the application, a high-carbon high-speed wire hot charging and hot delivery preparation method is provided, which comprises: high-quality molten iron→LD (80 tons) converter smelting→converter slag stopping tapping→ ladle deoxidization alloying→LF (80 tons) ladle refining furnace→Si-Ca wire feeding→ladle bottom argon blowing soft blowing→160 mm x 160 mm square billet continuous casting machine→casting blank→casting blank heating→rough rolling→medium rolling→water passing (primary controlled cooling)→finishing rolling (controlled rolling)→water passing (secondary controlled cooling)→wire drawing→air cooling (tertiary controlled cooling)→coiling→PF wire transportation→bundling→packaging transportation.

[0075] In actual use, the main process parameters of the LD converter smelting are as follows: volume after bricklaying: 58.5 m 3 ; volume ratio [V / T]: 0.83; tapping hole diameter [Din]: 150 mm; tapping hole angle: 10°; nozzle type: four-hole Laval; throat diameter: 31.86 mm; outlet diameter: 41.05 mm; nozzle and oxygen lance centerline angle: 12°40'; Mach number: 1.98; oxygen working pressure: 0.75-0.95 MPa; oxygen flow rate: 13000-16000 m 3 / h; ladle material: aluminum-magnesium-carbon brick and spinel castable.

[0076] The main process parameters of the LF ladle refining furnace are as follows: a bottom blowing gas permeable brick is used for bottom blowing refining (all using argon). The ladle is roasted using a regenerative roasting device (using coke oven gas). The refining system: online argon blowing and wire feeding after the furnace; 80 tons of double-station LF ladle refining furnace, heating capacity 3-5 ℃ / min, power 14 MVA.

[0077] Main process parameters of continuous casting: basic arc radius of 6-strand billet continuous caster: R10m; pouring section: 160mm x 160mm; length of billet: 3.8-12m. Section: 160mm x 160mm. Drawing speed: 1.5-3m / min, average 2.5m / min. Crystallizer: copper tube length 1000mm. Type of oscillation of crystallizer: sinusoidal oscillation. Frequency: 60-240 times / min. Amplitude ±5mm. Automatic control mode of liquid surface: Ce137 radioactive source. Detection accuracy: ±3mm. Water flow of crystallizer: 160m3 / h. Parameters of electromagnetic stirring: rated current of electromagnetic stirrer: 350A; rated voltage: 380V. Apparent power: 230KVA active power: 40KW(max) frequency: 2-8Hz(6Hz). Insulation level: H level. Water flow of crystallizer: 150m3 / h. Infrared length control system: detection length 9-12m; form of dummy bar: flexible chain type dummy bar.

[0078] Example 1

[0079] Converter smelting:

[0080] Condition of molten iron: C: 4.24%, Si: 0.55%, Mn: 0.50%, P: 0.13%, S: 0.022%, temperature: 1319°C by mass percent.

[0081] Charge structure: molten iron 68.4 tons, scrap steel 4.4 tons.

[0082] Consumption of first batch of dephosphorizing slag: lime 851kg, light-burned dolomite 1096kg; ore 1900kg; oxygen consumption 880m3 / N; blowing time: 236 seconds; temperature of semi-steel: 1321°C. Semi-steel slag sample: CaO: 42.19%, SiO2: 21.36%, TFe: 11.6%, R: 1.95. End point of converter: C: 0.13%, P: 0.013%, S: 0.017%. End point slag sample: CaO: 46.42%, SiO2: 13.43%, TFe: 17.82%, R: 3.47. Tapping temperature 1610°C. Tapping time 5 minutes 21 seconds, slag after 34mm. Deoxidation and alloying: micro-nitrogen carbon additive 6kg / ton of steel; silicon calcium barium 2kg / ton of steel; manganese iron 450kg, silicon iron 150kg, carbon chromium iron 110kg.

[0083] LF ladle refining furnace:

[0084] Lime 911kg; refining slag 112kg; submerged arc slag 146kg; fluorite 184kg; bauxite 100kg; silicon iron powder 100kg; silicon calcium wire 1m / ton of steel; soft argon flow 65NL / min, time 12 minutes 30 seconds; a[o] at the end of refining: 9.8ppm.

[0085] Continuous casting process:

[0086] Mould electromagnetic stirring parameters: 380 A, 4 Hz; mould water flow 120 t / h, secondary cooling with 0.75 L / kg of water; tundish liquid superheat 25 °C; casting speed 1.80 m / min.

[0087] Example 2

[0088] Converter smelting:

[0089] Hot metal conditions: C: 4.14%, Si: 0.42%, Mn: 0.35%, P: 0.129%, S: 0.011%, temperature: 1288 °C by mass percentage.

[0090] Charge structure: hot metal addition 69.3 tons, scrap steel 5.2 tons.

[0091] First dephosphorization slag consumption: lime 1800 kg, light-burned dolomite 475 kg; ore 806 kg; oxygen consumption 900 m 3 / N; blowing time: 241 seconds; semi-steel temperature: 1400 °C. Semi-steel slag sample: CaO: 47.50%, Si02: 20.41%, TFe: 11.05%, R: 2.31. Converter endpoint: C: 0.16%, P: 0.012%, S: 0.015%. Endpoint slag sample: CaO: 52.53%, Si02: 14.94%, TFe: 13.42%, R: 3.52. Tapping temperature 1613 °C. Tapping time 5 minutes and 25 seconds, slag after 30 mm. Deoxidation and alloying: micro-nitrogen carbon additive 6 kg / ton of steel; silicon-calcium-barium 2 kg / ton of steel; manganese iron 440 kg, silicon iron 155 kg, carbon-chromium iron 115 kg.

[0092] LF tundish refining furnace:

[0093] Lime 911 kg; refining slag 112 kg; submerged arc slag 136 kg; fluorite 152 kg; bauxite 113 kg; silicon iron powder 90 kg; silicon-calcium wire 1 m / ton of steel; soft-blow argon flow 60 NL / min, time 11 minutes and 40 seconds; refining end outgoing a[o]: 7.6 ppm.

[0094] Continuous casting process:

[0095] Mould electromagnetic stirring parameters: 380 A, 4 Hz; mould water flow 120 t / h, secondary cooling with 0.75 L / kg of water; tundish liquid superheat 29 °C; casting speed 1.82 m / min.

[0096] 82B Nitrogen content variation in each station: Converter (C: 0.16%; N: 0.0018%) -> entry into LF furnace (C: 0.53%; N: 0.0020%) -> exit from LF furnace (C: 0.54%; N: 0.0022%) -> tundish (C: 0.55%; N: 0.0016%) -> rolled material (C: 0.82%; N: 0.0045%).

[0097] Example 3

[0098] Converter smelting:

[0099] Hot metal conditions: C: 4.21%, Si: 0.54%, Mn: 0.55%, P: 0.13%, S: 0.022%, temperature: 1322°C, in mass percentage.

[0100] Charge structure: hot metal addition 68.5 tons, scrap steel 4.5 tons.

[0101] First dephosphorization slag consumption: lime 851 kg, light-burned dolomite 1099 kg; ore 1900 kg; oxygen consumption 880 m3 / N; blowing time: 238 seconds; semi-steel temperature: 1320°C. Semi-steel slag sample: CaO: 44.66%, Si02: 20.16%, TFe: 13.36%, R: 2.22. Converter end point: C: 0.15%, P: 0.012%, S: 0.018%. End point slag sample: CaO: 48.78%, Si02: 15.22%, TFe: 13.01%, R: 3.23. Tapping temperature 1615°C. Tapping time 5 minutes 05 seconds, slag after 39 mm. Deoxidation and alloying: micro-nitrogen carbonizer 6 kg / ton of steel; silicon-calcium-barium 2 kg / ton of steel; manganese iron 450 kg, silicon iron 150 kg, carbon-chromium iron 110 kg.

[0102] LF ladle refining furnace:

[0103] Lime 880 kg; refining slag 1102 kg; submerged arc slag 150 kg; fluorite 170 kg; bauxite 110 kg; silicon iron powder 120 kg; silicon-calcium wire 1 m / ton of steel; soft argon flow 66 NL / min, time 11 minutes 23 seconds.

[0104] Continuous casting process:

[0105] Mold electromagnetic stirring parameters: 380 A, 4 Hz; mold water flow 120 t / h, secondary cooling with 0.75 L / kg of water; tundish steel superheat 25°C; drawing speed 1.81 m / min.

[0106] 82B Change in nitrogen content at each station: Converter (C: 0.15%; N: 0.0022%) → entering LF furnace (C: 0.54%; N: 0.0025%) → exiting LF furnace (C: 0.54%; N: 0.0026%) → tundish (C: 0.54%; N: 0.0028%) → rolled material (C: 0.54%; N: 0.0030%).

[0107] Table 1 Composition of protective slag (wt%).

[0108]

[0109]

[0110] Table 2 Chemical composition of cast slab (wt%).

[0111] Serial number C Si Mn P S N Example 1 0.7 0.17 0.50 0.020 0.020 0.003 Example 2 1.2 0.30 0.90 0.015 0.005 0.0025 Example 3 0.83 0.23 0.80 0.012 0.006 0.0028 Comparative Example 1 0.79 0.17 0.70 0.008 0.008 0.002 Comparative Example 2 0.82 0.20 0.85 0.012 0.010 0.001 Comparative Example 3 0.84 0.22 0.80 0.011 0.007 0.0025

[0112] Table 3 Physical parameters of protective slag.

[0113] Serial number Melting point (°C) Melting rate (s) Viscosity (Pa s) Example 1 980 60 2.5 Example 2 1040 40 3.5 Example 3 1080 50 3.0 Comparative Example 1 950 45 2.0 Comparative Example 2 1100 65 4.0 Comparative Example 3 1080 35 2.5

[0114] Table 4 Heating process of high-speed wire rod.

[0115]

[0116]

[0117] Table 5 Wire breakage rate results of high-speed wire rod.

[0118] Serial number Breakage rate per hundred tons, times Example 1 1.7 Example 2 1.9 Example 3 2.1 Comparative Example 1 2.0 Comparative Example 2 2.1 Comparative Example 3 2.3

[0119] Wire breakage rate is a comprehensive index for evaluating the quality of steel material, and the average wire breakage rate of the high-speed wire rod prepared by the method provided in the embodiments of the present application is 2 times per hundred tons, which is better than the average wire breakage rate of 4 times per hundred tons on the market.

[0120] The hot charging and hot sending temperature of the steel provided in the embodiments of the present application is 450-650°C, compared with the normal "continuous casting-rolling" process, the hot charging and hot sending process can not only reduce the energy medium consumption of rolling high-speed wire rod by 20-30%, save costs, but also is conducive to the production organization on site, reduces the inventory of steel billets, and can also reduce the core-surface temperature difference of square billets after reheating of high-carbon steel, improve the uniform deformation degree of grains in the rolling process, and is conducive to reducing the composition. Thus, the method for preparing high-speed wire rod provided in the present application can better reduce the wire breakage rate of the rod.

[0121] The foregoing detailed description of the application has been presented for purposes of illustration and description. Various modifications and changes can be made to these embodiments without departing from the spirit and scope of the application. It is intended that the scope of the application should not be limited by the particular representative embodiments described above.

Claims

1. A method for preparing high-speed wire, characterized in that, The method includes: By controlling the chemical composition and physical parameters of the protective slag, molten steel with a set chemical composition is continuously cast to obtain a billet. The billet is hot-charged and hot-delivered to bring it to a set temperature. The billet with a set temperature is heated to reach the target temperature, and then rolled to obtain wire. The chemical composition of the protective slag includes: C, CaO, MgO, SiO2, Al2O3, Na2O, F, H2O; among which, The C content is 10%-20% by weight, the CaO content is 19%-29% by weight, and the MgO content is... The content of is: ≤5 wt%, the content of SiO2 is: 27.5 wt%-37.5 wt%, the content of Al2O3 is: ≤8 wt%, the content of Na2O is: 8 wt%-14 wt%, the content of F is: 3.5 wt%-7.5 wt%, and the content of H2O is: ≤0.5 wt%. The specified chemical components include: C, Si, Mn, P, S, N, Fe; among which, The C content is 0.7 wt%-1.2 wt%, the Si content is 0.17 wt%-0.30 wt%, the Mn content is 0.50 wt%-0.90 wt%, the P content is ≤0.020 wt%, the S content is ≤0.020 wt%, and the N content is ≤0.003 wt%. The protective slag has a melting point of 980℃-1080℃, a melting rate of 40s-60s, and a viscosity of 2.5Pa·s-3.5Pa·s.

2. The method according to claim 1, characterized in that, The basicity R of the protective slag is 0.73-0.

83.

3. The method according to claim 1, characterized in that, The set temperature is 450℃-650℃.

4. The method according to claim 1, characterized in that, The target temperature is 980℃-1030℃.

5. The method according to claim 1, characterized in that, The step of heating the billet to a set temperature so that the heated billet reaches the target temperature, followed by rolling, to obtain wire rod includes: Under the condition of a first set temperature, the billet with the set temperature is first heated; Under a second set temperature, the billet after the first heating is subjected to a second heating so that the heated billet reaches the target temperature, and then it is rolled to obtain wire.

6. The method according to claim 5, characterized in that, The first set temperature is 1150℃ -1220℃, the second set temperature is 1130℃-1190℃.

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