A method for manufacturing a high-aluminum steel slab

Abstract

The application relates to the technical field of steel smelting, in particular to a preparation method of a high-aluminum steel slab. Molten steel is refined by a LF+RH method, and Ti is added into the molten steel; wherein the content of N in the molten steel is controlled, and the weight ratio of the added amount of the Ti to the content of the N is controlled; the refined molten steel is subjected to continuous casting; wherein the continuous casting comprises the following steps: the refined molten steel is injected into a tundish, and an alkaline covering agent with a first set chemical component is added into the molten steel in the tundish; the molten steel in the tundish is injected into a crystallizer for first cooling, and a protective slag with set physical parameters and a second set chemical component is added into the molten steel in the crystallizer, so that a casting blank with a liquid core is obtained; under the condition of a set casting machine pulling speed, the casting blank with the liquid core is pulled to a secondary cooling area for second cooling, so that a high-aluminum steel slab is obtained. The application solves the technical problem that the existing high-aluminum steel slab has a concave crack on the surface.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of steel smelting, and particularly relates to a preparation method of high-aluminum steel slab. BACKGROUND

[0002] In order to realize energy saving and emission reduction, the materials in the automobile industry develop towards light weight and high strength. High-aluminum steel such as transformation induced plasticity (TRIP) steel and twinning induced plasticity (TWIP) steel has a good application prospect in the automobile field due to the perfect combination of plasticity and strength.

[0003] However, in the casting process of high-aluminum steel, the [Al] content in the molten steel is high, which is easy to react with SiO2, an important component in the traditional protective slag, so that the SiO2 content in the slag decreases, the basicity increases, and the Al2O3 content increases, resulting in the deterioration of the performance of the protective slag, the easy production of slag inclusion depression on the surface of the cast slab, and the serious influence on the continuous casting. At the same time, due to the high [Al] content in the steel, a large amount of AlN precipitates, resulting in poor high-temperature plasticity of the cast slab in the straightening area, and the problem of transverse cracks is prone to occur. SUMMARY

[0004] The present application provides a preparation method of high-aluminum steel slab to solve the technical problem of the existing high-aluminum steel slab surface depression cracks.

[0005] In a first aspect, the present application provides a preparation method of high-aluminum steel slab, which comprises:

[0006] The molten steel is refined by LF+RH method, and Ti is added to the molten steel; wherein the content of N in the molten steel is controlled, and the weight ratio of the added amount of Ti to the content of N is controlled;

[0007] The refined molten steel is continuously cast; wherein the continuous casting comprises:

[0008] The refined molten steel is injected into a tundish, and an alkaline covering agent with a first set chemical component is added to the molten steel in the tundish;

[0009] The molten steel in the tundish is injected into a crystallizer for first cooling, and a protective slag with a set physical parameter and a second set chemical component is added to the molten steel in the crystallizer, to obtain a cast slab with a liquid core;

[0010] Under the condition of a set casting machine pulling speed, the cast slab with the liquid core is pulled to a second cooling area for second cooling, to obtain a high-aluminum steel slab.

[0011] Optionally, the set physical parameter comprises a melting point and a viscosity; wherein the melting point is <1150℃, and the viscosity is 0.09-0.12 pa·s.

[0012] Optionally, the second set chemical components include: CaO, SiO2, MgO, Al2O3, Li2O, C and F;

[0013] wherein, in mass fraction,

[0014] the content of CaO is 35-45%, the content of SiO2 is 25-35%, the content of MgO is 1-3%, the content of Al2O3 is 1-3%, the content of Li2O is 2-5%, the content of C is 4-8%, and the content of F is 6-10%.

[0015] and simultaneously satisfy [CaO] / [SiO2]=1.1-1.3, [CaO] represents the weight of CaO, and [SiO2] represents the weight of SiO2.

[0016] Optionally, the molten steel in the tundish is injected into a crystallizer, and a protective slag with the set physical parameters and the second set chemical components is added to the molten steel in the crystallizer to obtain a casting billet with a liquid core, including:

[0017] the molten steel in the tundish is injected into a crystallizer, and a protective slag with the set physical parameters and the second set chemical components is added to the molten steel in the crystallizer, and vibration process parameters of the crystallizer are controlled to obtain a casting billet with a liquid core; wherein,

[0018] the vibration process parameters include: vibration frequency≥150 cpm, vibration amplitude≥3 mm, and negative slide-off time is 0.10-0.14 s.

[0019] Optionally, the content of N in the molten steel is≤0.004% in mass fraction.

[0020] Optionally, the weight ratio of the added amount of Ti to the content of N is 4-5.

[0021] Optionally, the first set chemical components include: CaO, MgO, Al2O3 and SiO2; wherein, in mass fraction,

[0022] the content of CaO is 40-46%, the content of MgO is 6-12%, the content of Al2O3 is 32-37%, and the content of SiO2 is≤6%.

[0023] Optionally, the refined molten steel is injected into a tundish, and an alkaline covering agent with the first set chemical components is added to the molten steel in the tundish, including:

[0024] the refined molten steel is injected into a tundish, and an alkaline covering agent with the first set chemical components is added to the molten steel in the tundish, and the superheat of the molten steel in the tundish is controlled; wherein,

[0025] The superheat of the molten steel in the tundish is 15-30 DEG C.

[0026] Optionally, the casting machine pulling speed is set to 1.0-1.2 m / min.

[0027] Optionally, under the condition of setting the casting machine pulling speed, the casting blank with the liquid core is pulled to the secondary cooling zone for the second cooling to obtain the high-aluminum steel slab, comprising:

[0028] Under the condition of setting the casting machine pulling speed, the casting blank with the liquid core is pulled to the secondary cooling zone for the gas mist cooling, and the process parameters of the gas mist cooling are controlled to obtain the high-aluminum steel slab; wherein the process parameters of the gas mist cooling comprise:

[0029] The specific water amount is 0.65-0.8 L / kg, the water amount at the outlet of the crystallizer is 0.1-0.15 M, and the water amount at the straightening zone is 0.3-0.35 M, wherein M represents the total water amount.

[0030] Compared with the prior art, the above technical solution provided by the embodiments of the present application has the following advantages:

[0031] The preparation method of the high-aluminum steel slab provided by the embodiments of the present application controls the N content, which is beneficial to reducing the AlN precipitation of the high-aluminum steel and improving the high-temperature plasticity at the straightening zone. A certain amount of Ti is added, the TiN precipitation temperature is higher than that of AlN, thereby playing a role in fixing nitrogen, and the TiN particles can be used as the heterogeneous core of AlN and the like, and the precipitates are more uniform and dispersed. The chemical components of the alkaline covering agent are controlled, the slag-steel secondary oxidation is effectively reduced, the pollution of the covering agent to the cleanliness of the molten steel is reduced, and the stability of the molten steel components is ensured. The physical parameters of the protective slag are controlled, the flowability of the protective slag is good, the consumption of the protective slag is updated quickly, and the performance is stable, which is beneficial to improving the slab quality and ensuring the smooth casting. The casting machine pulling speed is controlled, the liquid slag film between the crystallizer shell and the copper plate is prevented from becoming thin, and the lubrication performance is prevented from becoming poor. In summary, the present application solves the technical problem of the existing high-aluminum steel slab surface with concave cracks. BRIEF DESCRIPTION OF DRAWINGS

[0032] The accompanying drawings, which are incorporated into and form a part of the specification, illustrate one embodiment consistent with the present application and, together with the description, serve to explain the principles of the application.

[0033] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the accompanying drawings needed to be used in the embodiments or the prior art description will be briefly introduced. Obviously, for those skilled in the art, other drawings can also be obtained from these drawings without creative labor.

[0034] Figure 1A flowchart of a preparation method of a high-aluminum steel slab provided by an embodiment of the present application is shown. DETAILED DESCRIPTION

[0035] To make the objectives, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are some but not all of the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by a person of ordinary skill in the art without creative work fall within the scope of the present application.

[0036] Various embodiments of the present application can exist in the form of a range; it should be understood that the description in the form of a range 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 described range has been specifically disclosed all possible sub-ranges and single values in 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 in 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) in the indicated range.

[0037] In the present application, the orientation words such as "upper" and "lower" are specific to the drawing direction in the drawings. In addition, in the description of the present application, the terms "include", "contain" and the like mean "include but not limited to". In the present text, the relationship 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 relationship of the associated objects, which means that there can be three kinds of relationships, for example, A and / or B can represent the cases of A alone, A and B together, and B alone. Wherein A, 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 single item or any combination of multiple items. For example, "at least one of a, b or c", or "at least one of a, b and c", can represent a, b, c, a-b (i.e. a and b), a-c, b-c, or a-b-c, where a, b, c can be single or multiple.

[0038] Unless otherwise specifically indicated, all materials, reagents, and equipment used in this application are commercially available or are readily prepared by known methods.

[0039] In a first aspect, the application provides a preparation method of high-aluminum steel slab, please refer to Figure 1 , the method comprises:

[0040] S1, refining the molten steel by LF+RH method, and adding Ti into the molten steel; wherein, the content of N in the molten steel is controlled, and the weight ratio of the added amount of Ti to the content of N is controlled;

[0041] S2, continuously casting the refined molten steel; wherein, the continuous casting comprises: injecting the refined molten steel into a tundish, and adding an alkaline covering agent with a first set chemical composition into the molten steel in the tundish; injecting the molten steel in the tundish into a mold for first cooling, and adding a protective slag with a set physical parameter and a second set chemical composition into the molten steel in the mold, to obtain a casting blank with a liquid core; under the condition of a set casting speed, drawing the casting blank with the liquid core to a secondary cooling zone for second cooling, to obtain a high-aluminum steel slab.

[0042] In some embodiments, the set physical parameter comprises: a melting point and a viscosity; wherein, the melting point is <1150℃, and the viscosity is 0.09-0.12 pa·s.

[0043] The positive effects of controlling the melting point of the protective slag to be <1150℃ and the viscosity of the protective slag to be 0.09-0.12 pa·s are: the protective slag has good melting and flowing properties, the meniscus liquid slag in the mold has a fast updating rate, and the degeneration reaction is not easy to accumulate to cause deterioration of the lubrication effect. If the melting point of the protective slag is too high, it will slow down the melting rate to some extent. If the viscosity of the protective slag is too high, it will deteriorate the liquid slag flowability to some extent; if the viscosity of the protective slag is too low, it will cause the liquid slag to flow in too thick and unevenly to cause concave to some extent. Specifically, the melting point of the protective slag can be 1149℃, 1147℃, 1145℃, 1143℃, etc.; the viscosity of the protective slag can be 0.09 pa·s, 0.10 pa·s, 0.11 pa·s, 0.12 pa·s, etc.

[0044] In some embodiments, the second set chemical composition comprises: CaO, SiO2, MgO, Al2O3, Li2O, C, and F; wherein, in terms of mass fraction,

[0045] CaO is 35-45%, SiO2 is 25-35%, MgO is 1-3%, Al2O3 is 1-3%, Li2O is 2-5%, C is 4-8%, F is 6-10%;

[0046] and simultaneously satisfying [CaO] / [SiO2]=1.1-1.3, [CaO] represents the weight of CaO, and [SiO2] represents the weight of SiO2.

[0047] In the embodiments of the present application, the protective slag is a complex compound formed based on the CaO-SiO2-Al2O3 ternary phase diagram, with the addition of certain fluxing agents (CaF, Li2O, NaO, etc.) and control of melting rate substances (mainly carbon black and graphite). The influence of each component on the physical property parameters such as melting rate, melting point, and viscosity is complex and multi-faceted, and the physical properties of the protective slag are comprehensively controlled to achieve the desired metallurgical effect.

[0048] The main component contents of CaO-SiO2 system protective slag CaO and SiO2 are about 20-40%, and the composition ratio is generally determined by the required basicity (basicity affects melting point, heat transfer, viscosity, etc.). MgO and Al2O3 should be controlled to be less, otherwise it will increase the melting point and viscosity (MgO increases the melting point, and Al2O3 increases the melting point and viscosity). Then a certain amount of CaF, Na2O, Li2O is added to control the melting point and viscosity. C is mainly used to control the melting rate. The protective slag used in the embodiments of the present application is located in the low melting point region after modification reaction, has good fluidity, fast consumption and renewal of protective slag, stable performance, is conducive to improving the quality of the casting blank and ensuring smooth pouring. The slag uses CaO / SiO2 slag system design to increase the proportion of CaO and SiO2 in the original slag. The new protective slag avoids the high melting point region of calcium aluminum yellow long stone after modification reaction, and the mineral phase type after modification of the protective slag is low melting point phase 3CaO·2SiO2·CaF2 and 12CaO·7Al2O3. Specifically, the content of CaO can be 35%, 37%, 39%, 41%, 43%, 45%, etc. The content of SiO2 can be 25%, 27%, 29%, 31%, 33%, 35%, etc. The content of MgO can be 1%, 2%, 3%, etc. The content of Al2O3 can be 1%, 2%, 3%, etc. The content of Li2O can be 2%, 3%, 4%, 5%, etc. The content of C can be 4%, 5%, 6%, 7%, 8%, etc.

[0049] [CaO] / [SiO2] represents the basicity of the protective slag, and the positive effect of controlling the basicity to be 1.1-1.3 is: the basicity mainly controls the heat transfer, achieves the effect of slow cooling on the primary shell of the mold, and promotes the uniform growth of the primary shell. Specifically, the basicity can be 1.1, 1.2, 1.3, etc.

[0050] In some embodiments, the molten steel in the tundish is injected into a crystallizer, and a protective slag with set physical parameters and a second set chemical composition is added to the molten steel of the crystallizer to obtain a casting billet with a liquid core, comprising:

[0051] The molten steel in the tundish is injected into a crystallizer, and a protective slag with set physical parameters and a second set chemical composition is added to the molten steel of the crystallizer, and the vibration process parameters of the crystallizer are controlled to obtain a casting billet with a liquid core; wherein,

[0052] The vibration process parameters include: vibration frequency ≥ 150 cpm, vibration amplitude ≥ 3 mm, and negative stripping time of 0.10-0.14 s.

[0053] The positive effect of controlling the above vibration process parameters: using a high-frequency small-amplitude vibration mode, controlling the negative stripping time t N , on the one hand, it is beneficial to improve the consumption of protective slag and improve the lubricating effect, and on the other hand, the short negative stripping time is beneficial to reduce the depth of the casting billet vibration marks and thus reduce the transverse crack sensitivity. Specifically, the vibration frequency can be 150 cpm, 155 cpm, 160 cpm, etc.; the vibration amplitude can be 3 mm, 4 mm, 5 mm, etc.; and the negative stripping time can be 0.10 s, 0.11 s, 0.12 s, 0.13 s, 0.14 s, etc.

[0054] In some embodiments, the content of N in the molten steel is ≤0.004% by mass fraction.

[0055] The positive effect of controlling the content of N in the above molten steel to be ≤0.004%: it is beneficial to reduce the precipitation of AlN in high-aluminum steel and improve the high-temperature plasticity in the straightening area. If the content of N is too high, it will promote the precipitation of AlN in the straightening area to a certain extent, thereby deteriorating the high-temperature plasticity of the steel. Specifically, the content of N can be 0.004%, 0.0035%, 0.003%, etc.

[0056] In some embodiments, the weight ratio of the added amount of Ti to the content of N is 4-5.

[0057] The positive effect of controlling the weight ratio of the added amount of Ti to the content of N to be 4-5: since the precipitation temperature of TiN is higher than that of AlN, it plays a role in fixing nitrogen, and TiN particles can act as heterogeneous cores for AlN and other precipitates, making the precipitates more uniform and dispersed. If the weight ratio is too high, it will cause waste of cost to a certain extent, and too high Ti will affect the product performance; if the weight ratio is too low, it will not play the above nitrogen fixation effect to a certain extent. Specifically, the weight ratio can be 4, 4.5, 5.

[0058] In some embodiments, the first set chemical composition comprises CaO, MgO, Al2O3 and SiO2; wherein, in mass fraction,

[0059] The content of CaO is 40-46%, the content of MgO is 6-12%, the content of Al2O3 is 32-37%, and the content of SiO2 is ≤6%.

[0060] By using the basic covering agent, the secondary oxidation of the molten steel by the covering agent can be reduced, the inclusion content in the steel can be reduced, and the castability can be improved. Specifically, the content of CaO can be 40%, 42%, 44%, 46%, etc. The content of MgO can be 6%, 8%, 10%, 12%, etc. The content of Al2O3 can be 32%, 35%, 37%, etc. The content of SiO2 can be 6%, 5%, 4%, 3%, etc.

[0061] In some embodiments, the refining of the molten steel is followed by injecting the molten steel into a tundish and adding a basic covering agent with a set chemical composition to the molten steel in the tundish, comprising:

[0062] The refining of the molten steel is followed by injecting the molten steel into a tundish, adding a basic covering agent with a set chemical composition to the molten steel in the tundish, and controlling the superheat of the molten steel in the tundish; wherein,

[0063] The superheat of the molten steel in the tundish is 15-30°C.

[0064] The positive effect of controlling the superheat of the molten steel in the tundish to be 15-30°C is to ensure the quality of the cast slab. Specifically, the superheat of the molten steel in the tundish can be 15°C, 20°C, 25°C, 30°C, etc.

[0065] In some embodiments, the casting machine pulling speed is set to be 1.0-1.2 m / min.

[0066] The positive effect of setting the casting machine pulling speed to be 1.0-1.2 m / min is that the pulling speed and the protective slag lubrication are matched. If the pulling speed is too high, the liquid slag film between the shell and the copper plate will be thinned to some extent, and the lubrication performance will be poor. If the pulling speed is too low, the slag film will be too thick, and the liquid slag will flow unevenly. Specifically, the casting machine pulling speed can be 1.0 m / min, 1.1 m / min, 1.2 m / min, etc.

[0067] In some embodiments, under the condition of setting the casting machine pulling speed, the cast slab with a liquid core is pulled to a secondary cooling zone for second cooling to obtain a high-aluminum steel slab, comprising:

[0068] Under the condition of setting the casting speed, the slab with liquid core is pulled to the secondary cooling zone for air-atomizing cooling, and the process parameters of the air-atomizing cooling are controlled to obtain the high-aluminum steel slab; wherein the process parameters of the air-atomizing cooling include:

[0069] The specific water amount is 0.65-0.8 L / kg, the water amount at the outlet of the crystallizer is 0.1-0.15 M, and the water amount in the straightening zone is 0.3-0.35 M, wherein M represents the total water amount.

[0070] The specific water amount refers to the water amount used for cooling per unit weight of molten steel, and the air-atomizing cooling is performed in the fan-shaped section. The positive effect of controlling the process parameters of the air-atomizing cooling is that the peritectic high-aluminum steel has strong crack sensitivity, and the secondary cooling water is suitable for taking relatively weak cooling, and the water amount distribution in the straightening zone is controlled to avoid the third brittle zone during straightening, so as to prevent cracks from being generated during straightening in the low plasticity zone. The specific water amount can be 0.65, 0.70, 0.75, 0.8, etc.

[0071] The application will be further described in combination with specific examples. It should be understood that the examples are only used for illustrating the application and are not used for limiting the scope of the application. The experimental methods not specified in the following examples are generally determined according to the national standards. If there is no corresponding national standard, the international standard, the conventional condition, or the condition suggested by the manufacturer is used.

[0072] Example 1

[0073] A certain steel plant casts the high-aluminum steel continuous casting slab with the size of 230x1550 mm. The content of carbon in the high-aluminum steel is 0.14% by mass fraction, the content of Al is 0.5%, the molten steel adopts the LF+RH refining route, the content of N is 35 ppm, and 0.015% of Ti is added during refining, and the ratio is 4.3.

[0074] The high-alkalinity covering agent is used for the molten steel in the tundish, and the main components of the high-alkalinity covering agent by mass fraction are as follows: CaO: 44.3%, MgO:

[0075] 7.3%, Al2O3: 36.1%, SiO2: 5.1%. The superheat of the molten steel in the tundish is controlled to be 24 ℃.

[0076] The vibration frequency of the crystallizer is 165 cpm, the amplitude is 3 mm, and the negative slide time is 0.11 s.

[0077] The basicity R of the crystallizer protective slag is 1.22, the melting point is 1125 ℃, and the viscosity is 0.11 pa·s. The main components of the crystallizer protective slag by mass fraction are as follows: CaO: 40.5%, SiO2: 33.2%, MgO: 1.03%, Al2O3: 1.21%, Li2O: 3.0%, C: 5.67%, and F: 7.95%.

[0078] The drawing speed was controlled at 1.1 m / min, the secondary cooling was carried out by water mist cooling, the water flow M was 2805 L / min, the specific water quantity was 0.66 L / kg, the water flow at the lower outlet of the crystallizer was 0.11 M, i.e. 320 L / min, and the water flow at the straightening area was 0.32 M, i.e. 903 L / min. The high-aluminum steel was continuously and stably cast for 5 heats in this embodiment, and the cast slab was checked to be free of surface slag inclusion, depression and crack, and had good quality.

[0079] Example 2

[0080] A steel plant casted a high-aluminum steel continuous casting slab with a size of 230x1200 mm. The content of carbon in the high-aluminum steel was 0.08% by mass fraction, the content of Al was 0.6%, the molten steel adopted a LF+RH refining route, the content of N was 38 ppm, and 0.019% of Ti was added during refining, with a ratio of 5.

[0081] The high-basicity covering agent used for the molten steel in the tundish had the following main components by mass fraction: CaO: 40%, MgO: 6%, Al2O3: 32%, and SiO2: 6%. The superheat of the molten steel in the tundish was controlled at 15°C.

[0082] The vibration frequency of the crystallizer was 150 cpm, the amplitude was 3 mm, and the negative slide-off time was 0.14 s.

[0083] The basicity R of the crystallizer protective slag was 1.17, the melting point was 1145°C, and the viscosity was 0.09 pa·s. The main components of the protective slag by mass fraction were: CaO: 35%, SiO2: 30%, MgO: 2.1%, Al2O3: 2.1%, Li2O: 2.0%, C: 4%, and F: 6%.

[0084] The drawing speed was controlled at 1.15 m / min, the secondary cooling was carried out by water mist cooling, the water flow M was 2647 L / min, the specific water quantity was 0.75 L / kg, the water flow at the lower outlet of the crystallizer was 0.13 M, i.e. 344 L / min, and the water flow at the straightening area was 0.35 M, i.e. 926 L / min. The high-aluminum steel was continuously and stably cast for 5 heats in this embodiment, and the cast slab was checked to be free of surface slag inclusion, depression and crack, and had good quality.

[0085] Example 3

[0086] A steel plant casted a high-aluminum steel continuous casting slab with a size of 230x1400 mm. The content of carbon in the high-aluminum steel was 0.17% by mass fraction, the content of Al was 1.3%, the molten steel adopted a LF+RH refining route, the content of N was 35 ppm, and 0.014% of Ti was added during refining, with a ratio of 4.

[0087] The tundish molten steel adopts high basicity covering agent, and the main components of the covering agent are CaO: 46%, MgO: 12%, Al2O3: 37%, and SiO2: 5.1% in mass fraction. The superheat of the tundish molten steel is controlled to be 30 ℃.

[0088] The vibration frequency of the crystallizer is 165 cpm, the amplitude is 3 mm, and the negative stripping time is 0.12 s.

[0089] The basicity R of the crystallizer protective slag is 1.29, the melting point is 1125 ℃, and the viscosity is 0.11 pa·s. The main components of the protective slag are CaO: 45%, SiO2: 35%, MgO: 3%, Al2O3: 3%, Li2O: 5%, C: 8%, and F: 10% in mass fraction.

[0090] The drawing speed is controlled to be 1.1 m / min, the secondary cooling gas mist cooling is used, the water flow M is 2875 L / min, the specific water quantity is 0.8 L / kg, the water flow at the lower opening of the crystallizer is 0.15 M, that is, 431 L / min, and the water flow at the straightening area is 0.30 M, that is, 862 L / min. The high-aluminum steel is continuously and stably cast for 4 heats in the embodiment, and the cast slab is free of surface slag inclusion, depression and crack, and has good quality.

[0091] Comparative Example 1

[0092] A steel plant casts a high-aluminum steel continuous casting slab with a size of 230×1300 mm. The content of carbon in the high-aluminum steel is 0.14% in mass fraction, the content of Al is 0.5%, the molten steel adopts an LF+RH refining route, and the content of N is 43 ppm.

[0093] The tundish molten steel adopts a common covering agent, and the main components of the covering agent are CaO: 45.8%, MgO: 6.5%, Al2O3: 4.0%, and SiO2: 30.8% in mass fraction. The superheat of the tundish molten steel is controlled to be 20 ℃.

[0094] The vibration frequency of the crystallizer is 165 cpm, the amplitude is 3 mm, and the negative stripping time is 0.11 s.

[0095] The basicity R of the crystallizer protective slag is 1.31, the melting point is 894 ℃, and the viscosity is 0.13 pa·s. The main components of the protective slag are CaO: 22.7%, SiO2: 17.4%, MgO: 0.9%, Al2O3: 15.1%, Li2O: 4%, C: 7.9%, and F: 8.8% in mass fraction.

[0096] The drawing speed was controlled at 1.1 m / min, the secondary cooling was mist cooling, the water flow M was 2805 L / min, the specific water quantity was 0.66 L / kg, the water flow at the lower outlet of the crystallizer was 0.11 M, i.e. 320 L / min, and the water flow at the straightening area was 0.32 M, i.e. 903 L / min. The high-aluminum steel of the present comparative example was cast for 3 heats, and the surface slag inclusion and deep shake mark depression were serious, and the transverse crack defects were accompanied under the deep shake marks.

[0097] The above description is merely that of a specific implementation of the application, and persons skilled in the art can understand or implement the application based on the above description. Various modifications to the embodiments will be apparent to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the application. Therefore, the application will not be limited to the embodiments shown herein, but will conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method of producing a high aluminum steel slab, characterized by, The method comprises: The molten steel is refined by LF+RH method, and Ti is added into the molten steel; wherein, the content of N in the molten steel is controlled, and the weight ratio of the added amount of Ti to the content of N is controlled; the content of N in the molten steel is ≤0.004% in mass fraction; and the weight ratio of the added amount of Ti to the content of N is 4-5; The refined molten steel is continuously cast; wherein, the continuous casting comprises: The refined molten steel is poured into a tundish, and a basic covering agent with a first set chemical composition is added into the molten steel in the tundish; The molten steel in the tundish is poured into a mold for first cooling, and a protective slag with set physical parameters and a second set chemical composition is added into the molten steel in the mold, and vibration process parameters of the mold are controlled, to obtain a casting blank with a liquid core; wherein, the vibration process parameters comprise: vibration frequency ≥ 150 cpm, vibration amplitude ≥ 3 mm, and negative slip time is 0.10-0.14 s; Under the condition of a set casting machine casting speed, the casting blank with the liquid core is drawn to a secondary cooling zone for second cooling, to obtain a high-aluminum steel slab; The set physical parameters comprise: melting point and viscosity; wherein, the melting point is < 1150℃, and the viscosity is 0.09-0.12 Pa·s; The second set chemical composition comprises: CaO, SiO2, MgO, Al2O3, Li2O, C and F; wherein, the content of CaO is 35-45% in mass fraction, the content of SiO2 is 25-35% in mass fraction, the content of MgO is 1-3% in mass fraction, the content of Al2O3 is 1-3% in mass fraction, the content of Li2O is 2-5% in mass fraction, the content of C is 4-8% in mass fraction, and the content of F is 6-10% in mass fraction; and simultaneously, [CaO] / [SiO2]=1.1-1.3 is met, [CaO] represents the weight of CaO, and [SiO2] represents the weight of SiO2; The first set chemical composition comprises: CaO, MgO, Al2O3 and SiO2; wherein, the content of CaO is 40-46% in mass fraction, the content of MgO is 6-12% in mass fraction, the content of Al2O3 is 32-37% in mass fraction, and the content of SiO2 is ≤6% in mass fraction.

2. The method of claim 1, wherein, The pouring of the refined molten steel into the tundish and the adding of the basic covering agent with the set first chemical composition into the molten steel in the tundish comprise: The pouring of the refined molten steel into the tundish and the adding of the basic covering agent with the first set chemical composition into the molten steel in the tundish, and the control of the superheat of the molten steel in the tundish; wherein, The superheat of the molten steel in the tundish is 15-30℃. The set casting machine casting speed is 1.0-1.2 m / min.

3. The method of claim 1, wherein, Under the condition of the set casting machine casting speed, 4. The method according to claim 1 or 3, characterized in that, The drawing of the casting blank with the liquid core to the secondary cooling zone for the second cooling to obtain the slab comprises: Under the condition of the set casting machine casting speed, the drawing of the casting blank with the liquid core to the secondary cooling zone for the gas mist cooling, and the control of process parameters of the gas mist cooling to obtain the slab; wherein, the process parameters of the gas mist cooling comprise: ​ The specific water amount is 0.65-0.8 L / kg, the water amount at the lower outlet of the crystallizer is 0.1-0.15 M, and the water amount in the straightening area is 0.3-0.35 M, M representing total water amount.

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