CN115125434B - Low-carbon high-nitrogen tinned substrate and slab continuous casting production method thereof - Google Patents
Low-carbon high-nitrogen tinned substrate and slab continuous casting production method thereof Download PDFInfo
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/02—Ferrous alloys, e.g. steel alloys containing silicon
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
- B22D11/00—Continuous casting of metals, i.e. casting in indefinite lengths
- B22D11/16—Controlling or regulating processes or operations
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
- B22D11/00—Continuous casting of metals, i.e. casting in indefinite lengths
- B22D11/16—Controlling or regulating processes or operations
- B22D11/22—Controlling or regulating processes or operations for cooling cast stock or mould
- B22D11/225—Controlling or regulating processes or operations for cooling cast stock or mould for secondary cooling
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/001—Ferrous alloys, e.g. steel alloys containing N
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- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/002—Ferrous alloys, e.g. steel alloys containing In, Mg, or other elements not provided for in one single group C22C38/001 - C22C38/60
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/04—Ferrous alloys, e.g. steel alloys containing manganese
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
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- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/06—Ferrous alloys, e.g. steel alloys containing aluminium
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Abstract
The invention discloses a low-carbon high-nitrogen tinned substrate and a slab continuous casting production method thereof, wherein the steel grade of the substrate consists of the following elements in percentage by mass: c:0.01 to 0.12 percent, 0<Si≤1.0％，0<Mn is less than or equal to 1.0%, S is less than or equal to 0.020%, P is less than or equal to 0.040%, al: 0.005-0.12%, N: 0.010-0.020%, and Mn/S is more than or equal to 50, 0.5X10 ‑8 ≤[Al]·[N]The product is less than or equal to 24 multiplied by 10 ‑8 The balance being Fe and unavoidable impurities. After continuous annealing of the continuous casting slab through hot rolling and cold rolling, the HR30T hardness of the hardening and tempering degree T-5CA can reach 67-73; after the secondary cold rolling, the tensile strength in the rolling direction is about 65-75 kg/mm 2 。
Description
Technical Field
The invention relates to a manufacturing method of a low-carbon high-nitrogen tinned substrate, which is free from longitudinal cracks and transverse cracks in slab continuous casting and belongs to the technical field of metallurgy.
Background
The tin plate is a cold rolled low-carbon thin steel plate or steel strip with pure tin plated on two sides, and the tin plate is formed into a tin plate with a relatively complex surface composition and structure after the treatment steps of alkali washing, acid washing, electrotinning, reflow, passivation, electrostatic oiling and the like. Tin plating plates combine the strength and mechanical properties of steel with the corrosion resistance, weldability and aesthetics of tin, and are currently widely used in the packaging field of canned foods, beverages and the like. Along with the change of the living standard of people and the continuous growth of export trade, the food industry in China rapidly develops, the market demand and the yield of various foods such as cans, fruit juice, eight-treasure porridge and the like also continuously increase, the demand for packaging raw material tin plate is greatly increased, the rolling and baking demands for tin plate base plates are higher and higher, and the low-carbon high-nitrogen tin plate variety is also the main development direction of tin plate products
In the continuous casting process of the carbon-containing and nitrogen-containing steel, cracks can possibly occur from the crystallizer to the secondary cooling zone. When the continuous casting blank is in the crystallizer, element segregation among dendrites exists in the process of solidification of molten steel, on the other hand, because cooling at a vibration mark is weaker, generated austenite grains are coarse, the solidification thickness of the whole blank shell is uneven, cracks are easy to generate at the place where the blank shell is thin, and precipitation of oxysulfide of ferro-manganese at an austenite grain boundary weakens the grain boundary to initiate the cracks. After entering the secondary cooling zone, the high temperature zone can greatly reduce the thermoplasticity of the continuous casting blank due to the generation of precipitates such as AlN, mnS and the like in an austenite grain boundary and the generation of ferrite along with the generation of ferrite transformation from austenite to ferrite along with the reduction of temperature. On the basis, if unreasonable conditions such as uneven cooling, uncomfortable strength and the like exist in secondary cooling, cracks can be generated and expanded in a large amount after continuous casting blanks are subjected to external stresses such as bending, straightening and thermal stress, and macroscopic corner transverse cracks are formed. As the temperature is further lowered, cementite formed at the grain boundaries also weakens the grain boundaries, enhancing crack sensitivity.
Disclosure of Invention
The invention aims to provide a low-carbon high-nitrogen tinned substrate capable of improving the quality of continuous casting blanks.
The technical problems to be solved by the method can be implemented by the following technical schemes.
The low-carbon high-nitrogen tinned substrate is characterized in that the steel grade of the substrate consists of the following elements in percentage by mass:
C：0.01～0.12％，0<Si≤1.0％，0<mn is less than or equal to 1.0%, S is less than or equal to 0.020%, P is less than or equal to 0.040%, al: 0.005-0.12%, N: 0.010-0.020%, and Mn/S is more than or equal to 50, 0.5X10 -8 ≤[Al]·[N]The product is less than or equal to 24 multiplied by 10 -8 The balance being Fe and unavoidable impurities.
As a preferred embodiment of the technical scheme, the steel grade of the substrate consists of the following elements in percentage by mass:
c:0.03 to 0.10 percent (carbon is used as solid solution strengthening element in the tin-plated substrate, the C content of converter tapping is 0.03 to 0.04 percent, from the aspects of meeting product characteristics and cost, the C is preferably more than or equal to 0.03 percent, but when the carbon content exceeds 0.10 percent, the plasticity of the steel is low, the transverse cracks of continuous casting angles are most likely to occur, the service life is reduced, and the C is preferably less than or equal to 0.10 percent);
si is 0< 0.7% or less (the invention discovers that Si can also increase the solid solution strengthening performance of a tinned substrate, when Si is more than or equal to 0.7%, the rate of increase of the solid solution strengthening capability is slow, and if Si exceeds 1.0%, the brittleness of the material is increased and the corrosion resistance is reduced, and the invention prefers Si to be less than or equal to 0.7%);
mn is 0< Mn is less than or equal to 0.8 percent (Mn/S is more than or equal to 50 percent, the toughness and solid solution strength of steel can be increased simultaneously, mn/S can be effectively improved along with the increase of Mn content, the critical strain of the material, namely the crack resistance capability is enhanced, meanwhile, S content is also considered in Mn addition, and from the aspects of cost and performance comprehensive consideration, a certain Mn/S ratio is satisfied;
s is less than or equal to 0.016 percent (sulfur is a harmful element, the lower the content is, the better the content is, but a large amount of lime and low-temperature control are needed in the refining process, the consumption is large, the smelting period is long, and the preferable S is less than or equal to 0.016 percent through Mn/S ratio matching, so that the requirement can be met);
p is less than or equal to 0.020 percent (sulfur is a harmful element, the lower the content is, the better the content is, the high-temperature P removal in the converter process is also required, the consumption is large, the smelting period is long, and the requirement can be met by optimizing the P to be less than or equal to 0.020 percent from the viewpoint of meeting the product performance);
al:0.01 to 0.08 percent (AlN is used as deoxidizer and plays a role of refining grains, and a large amount of fine AlN in steel is separated out along grain boundaries, so that the strength of austenite grain boundaries is reduced, the austenite grain boundaries are easy to crack under the action of stress, and the plasticity of a tinned substrate is reduced, so that the Al content is controlled within the range of 0.01 to 0.08 percent, and the effect is optimal);
n: 0.010-0.018% (N has the main function of improving the processing performance of continuous annealing, surface light rolling and the like of the tinning plate), when the N content is lower than 0.01 percent, the effect of refining grains and cold processing performance is not obvious, but the increase of [ N ] content in steel can cause the widening of a third brittle zone of a continuous casting blank, particularly the enhancement of the sensitivity of transverse crack of a rear corner with the N content higher than 0.018 percent, so the N content is preferably controlled in the range of 0.010-0.018 percent;
and Mn/S is more than or equal to 50,2 multiplied by 10 -8 ≤[Al]·[N]The product is less than or equal to 20 multiplied by 10 -8 The balance being Fe and unavoidable impurities.
In the tin plate, alN is used as deoxidizer and has the function of refining grains, the N content also has the function of improving the continuous annealing, surface light rolling and other processing functions of the tin plate, and the Al is controlled]·[N]The product content realizes the above functions. The components of the inventionWhen [ Al]·[N]The product is larger than 2 multiplied by 10 -8 After that, the action effect of refining the crystal grains and the effect of improving the cold processing performance are obviously improved; but when [ Al]·[N]The product is larger than 20 multiplied by 10 -8 After that, the grain refining effect and the cold processing performance improving effect are close to saturation, and the Al is continuously increased]·[N]The integration content increases the temperature of the surface of the secondary cooling area and oscillates at low temperature along with the continuous casting process, alN precipitated phases are gathered at the crystal boundary of the casting blank, and the risk of inter-crystal cracks is initiated. Therefore, the invention is preferably 2X 10 -8 ≤[Al]·[N]The product is less than or equal to 20 multiplied by 10 -8 。
Another technical problem to be solved by the invention is to provide a steel slab continuous casting manufacturing method of a low-carbon high-nitrogen tinned substrate, which can realize slab continuous casting without longitudinal cracks and transverse cracks.
The method adopts the following technical scheme.
The steel plate blank continuous casting production method of the low-carbon high-nitrogen tinned substrate is characterized in that in the continuous casting process,
the continuous casting secondary cooling zone is divided into 0-8 sections along the length direction of the casting machine, and 9 sections are added.
The second cooling areas 0 and 1 are controlled based on pulling speed, the average pulling speed is controlled to be 1.0-1.8 m/min, and the total specific water content of the second cooling water is controlled to be 1.2-1.6L/kg;
the second cooling zone 2-8 adopts target temperature control, and the target temperature is 650-750 ℃;
the secondary cooling electromagnetic stirring current is 1200-2200A, and the stirring frequency is 2.0-4.0 Hz; the superheat degree of the molten steel in the tundish is controlled to be 10-50 ℃; the water quantity of the wide surface of the crystallizer is 2000-2800L/min; the insertion depth of the water gap of the continuous casting crystallizer is controlled to be 100-160 mm; the taper of the narrow surface of the crystallizer is 1.05 to 1.25.
As a further improvement of the production method, in the slab continuous casting process, the thickness of the slab section is controlled to be (200-300) mm (800-1650) mm.
As a preferable scheme, the two cooling areas 0 and 1 are controlled based on the pulling speed, the average pulling speed is controlled to be 1.2-1.70 m/min, and the specific water quantity is controlled to be 1.3-1.5L/kg. The invention discovers that if the average pulling speed is higher than 1.70m/min, the continuous casting steel amount is large, the risk of casting blank being rolled into mold flux is aggravated, white spot defect is easy to occur after rolling, and the initial green shell in the crystallizer is thinner along with the pulling speed, the casting blank is unevenly cooled, and longitudinal cracks and even steel leakage are easy to occur. After the casting blank comes out of the crystallizer, the surface temperature of the casting blank is about 1000 ℃, the casting blank directly enters the sections 0 and 1 of the secondary cooling zone, the pure water cooling rate in the crystallizer is high, the gas mist cooling rate in the secondary cooling zone is low, so that the surface temperature of the casting blank can rise to 1100 ℃, the precipitation peak temperature of AlN corresponds to 800-1100 ℃, in order to enable the surface temperature of the casting blank to be in a rapid AlN precipitation peak temperature interval, the surface of the casting blank can be guaranteed to be cooled at a certain cooling rate by controlling the water meter based on the pulling speed, and the research shows that the average pulling speed is controlled to be 1.2-1.70 m/min, and the effect is optimal. Further, if the pulling speed is lower than 1.2m/min, the casting blank stays in the crystallizer for a long time, so that a great amount of MnS and AlN are easily precipitated in advance due to rapid temperature drop, and the crack sensitivity of the casting blank is enhanced; meanwhile, considering the control of the steelmaking continuous casting production rhythm, the continuous casting pulling speed is not too low, so the average pulling speed is preferably controlled to be 1.2-1.70 m/min. The second cooling area 0 and the No. 1 are controlled based on a pull-speed water meter, the average pull-speed is controlled to be 1.2-1.70 m/min, and the preferable specific water quantity scheme is 1.3-1.5L/kg.
As a preferable scheme, the second cooling zone 2-8 adopts target temperature control, and the target temperature is 675-750 ℃. Based on the above expression, the surface temperature of the casting blank is reduced to below 800 ℃ in the second cooling zone 0 and the second cooling zone 1 through the control of a pull-speed water meter. The second cooling zone 2-8 is controlled by target temperature, and the method has the advantages of precisely controlling the second cooling water amount based on a mathematical model and a target temperature method, ensuring that the surface temperature of the casting blank is controlled to 650-750 ℃, ensuring that the casting blank in the temperature range of the alloy system has relatively high plasticity, ensuring that the highest plasticity temperature range is 675-750 ℃, straightening the casting blank in the temperature range, ensuring that the casting blank is not easy to crack and ensuring good surface quality.
As a preferable scheme, the secondary cooling electromagnetic stirring current is 1400-2000A, and the stirring frequency is 2.5-3.5 Hz. The invention discovers that after the electromagnetic stirring current intensity is higher than 1400A, the effect of improving the central quality of a casting blank and columnar crystal dendrites is remarkable; the electromagnetic stirring current intensity is higher than 2000A, the fluctuation of the liquid level of the crystallizer begins to become larger, and the negative segregation rating of the casting blank is increased; the invention preferably takes the electromagnetic stirring current of 1400-2000A and the stirring frequency of 2.5-3.5 Hz in the secondary cooling area.
As a preferable scheme, the superheat degree of molten steel in the tundish is controlled at 20-40 ℃. The improvement of the degree of superheat of the molten steel is beneficial to preventing the slag from being rolled up by the low-carbon high-nitrogen tinplate crystallizer, and when the degree of superheat of the molten steel is higher than 20 ℃, the melting effect of the protective slag is found to be good, the liquid protective slag is gradually increased, and the probability of rolling up the solid protective slag is reduced. But after the overheat is higher than 40 ℃, the casting blank is found to have long solidification time and sufficient selective crystallization, so that the internal quality problem of the casting blank is aggravated; therefore, the superheat degree of the molten steel in the tundish is preferably controlled to be 20-40 ℃.
As a preferable scheme, the wide water volume of the crystallizer is 2200-2500L/min. According to the solidification characteristics of the low-carbon nitrogen-containing tin plate, a crystallizer slow cooling change mode is adopted, so that longitudinal cracking is restrained, the initial solidification position and solidification rate of a blank shell are reduced, non-uniformity is weakened, and crack tendency is restrained. When the water quantity of the wide surface of the crystallizer exceeds 2500L/min, the difference of water temperature difference of copper plates at two sides of the wide surface of the crystallizer is increased, which indicates that the heat transfer becomes uneven. When the water quantity of the wide surface of the crystallizer is lower than 2200L/min, the thickness of the blank shell at the outlet of the crystallizer is obviously thinned, and when the pulling speed is 1.7-1.8 m/min, the thickness requirement of the blank shell at the outlet of the crystallizer is met, so that the risk of steel leakage of the crystallizer is increased. Therefore, the preferable wide-surface water quantity of the crystallizer is 2200-2500L/min.
As a preferable scheme, the water gap insertion depth of the continuous casting crystallizer is controlled to be 120-150 mm. For the low-carbon high-nitrogen tinning plate, the mold gate insertion depth determines the mold flow field and slag melting conditions, and when the mold gate insertion depth becomes shallow, the mold flux is beneficial to melting and adding the liquid mold flux; however, if the insertion depth becomes too shallow, the fluctuation of the liquid level of the crystallizer is too large, and the probability of slag inclusion of the mold flux is increased. Meanwhile, if the water gap of the crystallizer is inserted too deeply, the solid casting powder is not melted yet, and the floating of inclusions in molten steel is also not facilitated, and the risks that the inclusions and the casting powder are involved in a casting blank are also increased. Therefore, the insertion depth of the nozzle is preferably controlled to be 120-150 mm.
Preferably, the taper of the narrow surface of the crystallizer is 1.10-1.20. The taper of the crystallizer is used for compensating the shrinkage of the solidified shell, reducing the generation of air gaps between the crystallizer and the casting blank and enhancing the uniformity of heat transfer. The invention is applied to the production process, and the taper of the crystallizer is found to be too small, when the taper is lower than 1.1, the solidified blank shell is easy to bulge, and the casting blank is easy to dent; otherwise, if the taper is larger than 1.20, the friction force between the shell and the crystallizer copper plate starts to increase, so that the casting blank is at risk of longitudinal cracking, and meanwhile, the casting blank contacts with the crystallizer copper plate, so that the crystallizer copper plate is seriously worn and has a reduced service life. Therefore, the taper of the narrow face of the crystallizer is preferably controlled to be 1.10-1.20.
The technical scheme mechanism and the limiting reasons of the invention are as follows:
C：0.01～0.12％，0<Si≤1.0％，0<mn is less than or equal to 1.0%, S is less than or equal to 0.020%, mn/S is more than or equal to 50%, P is less than or equal to 0.040%, al: 0.005-0.12%, N:0.010 to 0.020%, 0.5X10) -8 ≤[Al]·[N]The product is less than or equal to 24 multiplied by 10 -8 The balance being Fe and unavoidable impurities.
C: carbon is used as a solid solution strengthening element in the tin-plated substrate, and C is more than or equal to 0.01% from the standpoint of meeting product characteristics and cost; however, when the carbon content exceeds 0.12%, continuous casting angle transverse cracks are easy to generate, and the service life is reduced. Therefore, the C content of the present invention is controlled to be 0.01-0.12%.
Si: silicon is generally carried in from raw materials and alloys; the silicon content is high and can increase the solid solution strengthening property of the tin-plated substrate, but if added in a large amount, the brittleness of the material is increased and the corrosion resistance is lowered, so that the silicon content is not excessively high. Therefore, the Si content of the invention is controlled to be less than or equal to 1.0 percent.
P and S: phosphorus and sulfur are harmful elements, and can generate brittle materials with low melting point and have high crack occurrence tendency, so that the invention is controlled to be less than or equal to 0.040 percent of P and less than or equal to 0.020 percent of S.
Mn: manganese generally increases the toughness of steel, and increases the strength of steel through solid solution strengthening; however, as Mn and S are combined to form MnS, the generation of transverse cracks of the casting blank angle is aggravated, and researches show that Mn/S is more than or equal to 50, the critical strain of the material can be improved, and the transverse cracks of the angle are improved. Therefore, the Mn is controlled to be less than or equal to 1.0 percent and the Mn/S is controlled to be more than or equal to 50 percent.
Al: al is used as a deoxidizer, and a proper amount of AlN can play a role in refining grains; a large amount of fine AlN in the steel is separated out along the grain boundary, the austenitic grain boundary strength is reduced, the steel is easy to crack along the grain boundary under the action of stress, and the plasticity of the tin-plated substrate is reduced, so that the Al content must be controlled within a reasonable range. Therefore, the Al content of the present invention is controlled to be in the range of 0.005 to 0.12%.
N: the addition of N is beneficial to the subsequent continuous annealing, surface light rolling and other processing; however, an increase in the [ N ] content in the steel causes a widening of the third brittle zone of the continuous casting slab and an increase in the sensitivity to transverse cracks. Therefore, the N of the present invention is controlled to be in the range of 0.010 to 0.020%.
[Al]·[N]The product directly influences the occurrence of transverse cracks of the casting blank angle, and is controlled to be 0.5 multiplied by 10 according to research and practical results -8 ≤[Al]·[N]The product is less than or equal to 24 multiplied by 10 -8 And the occurrence rate of the transverse angle crack is reduced.
In the continuous casting process, after entering the secondary cooling zone, the thermal plasticity of the continuous casting blank is greatly reduced due to the generation of precipitates such as AlN, mnS and the like in an austenite grain boundary in a high-temperature zone and the generation of ferrite along with the generation of ferrite by austenite transformation generated along with the reduction of temperature. Summarizing to obtain that the steel grade is suitable for adopting a forced cooling process system in a secondary cooling area; in the continuous casting process of the steel plate blank of the low-carbon high-nitrogen tinned substrate, the second cooling zone 0 and the first section 1 are controlled based on the pulling speed, the average pulling speed is controlled to be 1.0-1.80 m/min, and the specific water quantity is controlled to be 1.2-1.6L/kg; the second cooling zone 2-8 adopts target temperature control, and the target temperature is 650-750 ℃.
In the slab continuous casting process, when the thickness of a slab with a section x the width of the slab is (200-300) mm x (800-1650) mm, if the average pulling speed is higher than 1.80m/min, the primary slab shell is thinner, the casting blank is unevenly cooled, and longitudinal cracks and even steel leakage are easy to generate; considering the steelmaking continuous casting rhythm and the high drawing speed target, if the average drawing speed is not lower than 1.0m/min, the overall production capacity of the continuous casting machine is not affected; therefore, the average pulling speed of the invention is controlled to be 1.0-1.80 m/min.
In order to improve the segregation problem possibly caused in the continuous casting process, the invention adds a secondary cooling zone electromagnetic stirring process. If the electromagnetic stirring current intensity is lower than 1200A, the effect of improving the center quality of the casting blank is not achieved; the electromagnetic stirring current intensity is higher than 2200A, the fluctuation of the liquid level of the crystallizer is large, and the casting blank is easy to generate negative segregation; a large number of experiments show that the electromagnetic stirring current intensity is controlled to be 1200-2200A, and the stirring frequency is controlled to be 2-4 Hz.
If the superheat degree of molten steel in the continuous casting process is lower than 10 ℃, the molten steel has poor fluidity, which is easy to cause the freezing of steel at the water gap of a crystallizer and force the interruption of casting, and the casting powder has poor melting effect; if the superheat degree of the molten steel is higher than 50 ℃, segregation is very easy to occur, so that the solidification time is long, the selective crystallization is sufficient, and the quality problem of a casting blank is aggravated; therefore, the superheat degree of the molten steel in the tundish is controlled to be 10-50 ℃.
Unlike the prior art in which the water quantity of the broad surface of the crystallizer is controlled to be more than 3000-3500L/min, in some preferred embodiments, in order to prevent cracks and depressions from being generated in the crystallizer, a weak cooling mode is adopted, and the water quantity of the broad surface of the crystallizer can be controlled to be 2000-2800L/min.
If the insertion depth of the crystallizer water gap is too shallow, the impact of the water gap flow on the steel slag interface is strong, the reaction probability of molten steel and the crystallizer casting powder is increased, and meanwhile, the meniscus slag-rolling probability is increased; if the water gap of the crystallizer is inserted too deeply, the casting blank is easy to crack; therefore, the water gap insertion depth of the continuous casting crystallizer designed by the invention is controlled to be 100-160 mm.
During solidification, an air gap is formed between the mold and the cast blank, which causes uneven heat transfer, uneven thickness of the grown shell, and easy formation of surface pits or cracks, so that an inverted taper is provided to compensate for shrinkage of the solidified shell. If the taper of the crystallizer is too small, the blank shell is easy to bulge; if the taper is too large, the friction force between the blank shell and the crystallizer copper plate is increased. The mold taper is generally selected based on the steel grade, the width of the strand and the draw rate. The narrow surface taper of the crystallizer designed by the invention is 1.05-1.25.
Compared with the prior art, the low-carbon high-nitrogen tinned substrate and the slab continuous casting production method thereof developed by the invention have the characteristics of good surface and center quality of continuous casting billets and the like, and are also beneficial to improving the quality of the continuous casting billets. The technology is a key technology for realizing continuous casting production and quality assurance of low-carbon high-nitrogen tinned substrate slabs.
Further, compared with the prior art, the low-carbon high-nitrogen tinned substrate slab continuous casting production method developed by the invention has the characteristics of good surface and center quality of a continuous casting blank, can fully exert the advantages of continuous casting production, can inhibit the generation of pits and cracks of a casting blank, remarkably improves the surface and center quality of the casting blank, and can realize multi-furnace continuous casting. The technology is a key technology for realizing continuous casting production and quality assurance of low-carbon high-nitrogen tinned substrate slabs. The method has popularization and application values for developing nitrogen-containing varieties and optimizing processes of enterprises adopting continuous casting process flows to realize production and test, improves productivity, reduces production cost and enhances comprehensive competitiveness of enterprises.
Detailed Description
The low-carbon high-nitrogen tinned substrate and the slab continuous casting process thereof according to the present invention will be further explained and illustrated with reference to specific examples, but the explanation and illustration do not unduly limit the technical scheme of the present invention.
Examples 1 to 6
The following table 1 lists the mass percentages of each chemical element in the low carbon high nitrogen tin plated substrates of examples 1 to 6.
Table 1 (wt.%), the balance Fe and other unavoidable impurities other than P, S, N
The low-carbon high-nitrogen tinned substrates of examples 1-6 of the invention were prepared by the following continuous casting production process:
in the continuous casting process, the second cooling areas 0 and 1 are controlled to be 1.0-1.80 m/min based on the pulling speed, and the specific water quantity is controlled to be 1.2-1.6L/kg; the second cooling zone 2-8 adopts target temperature control, and the target temperature is 650-750 ℃; the secondary cooling electromagnetic stirring current is 1200-2200A, and the stirring frequency is 2-4 Hz; the superheat degree of the molten steel in the tundish is controlled to be 10-50 ℃; the wide water volume of the crystallizer is 2000-2800L/min, and the narrow water volume is 450-550L/min; the insertion depth of the water gap of the continuous casting crystallizer is controlled to be 100-160 mm; the taper of the narrow surface of the crystallizer is 1.05 to 1.25.
Table 2 below sets forth specific process parameters for the manufacturing process of the low carbon high nitrogen tin plated substrates of examples 1-6.
Table 2.
The HR30T hardness of the tempering degree T-5CA can reach 67-73 after continuous withdrawal of the continuous casting slab produced by adopting the low-carbon high-nitrogen tinning substrate and the slab continuous casting method thereof is hot rolled and cold rolled, and is higher than that of the traditional steel plate with the tempering degree T-5CA by 62-68; after the secondary cold rolling, the tensile strength in the rolling direction is about 65-75 kg/mm 2 Is higher than the traditional 60-65 kg/mm 2 。
Finally, it should be noted that: the above embodiments are only for illustrating the present invention and not for limiting the technical solution described in the present invention; thus, while the invention has been described in detail with reference to the various embodiments described above, it will be understood by those skilled in the art that the invention may be modified or equivalents; all technical solutions and modifications thereof that do not depart from the spirit and scope of the present invention are intended to be included in the scope of the appended claims.
Claims (10)
1. The low-carbon high-nitrogen tinned substrate is characterized in that the steel grade of the substrate consists of the following elements in percentage by mass:
C：0.01～0.12％，0<Si≤1.0％，0<mn is less than or equal to 1.0%, S is less than or equal to 0.020%, P is less than or equal to 0.040%, al: 0.005-0.12%, N: 0.010-0.020%, and Mn/S is more than or equal to 50, 0.5X10 -8 ≤[Al]·[N]The product is less than or equal to 24 multiplied by 10 -8 The balance of Fe and unavoidable impurities;
wherein, the preparation of the steel plate blank of the substrate adopts a continuous casting production method of the following continuous casting procedure:
dividing a continuous casting secondary cooling zone into sections 0-8 along the length direction of a casting machine, and adding 9 sections in total;
the second cooling area 0 and the No. 1 are controlled based on a pull-speed water meter, the average pull-speed is controlled to be 1.0-1.8 m/min, and the specific water quantity is controlled to be 1.2-1.6L/kg;
the second cooling zone 2-8 adopts target temperature control, and the target temperature is 650-750 ℃;
the secondary cooling electromagnetic stirring current is 1200-2200A, and the stirring frequency is 2.0-4.0 Hz; the superheat degree of the molten steel in the tundish is controlled to be 10-50 ℃; the water quantity of the wide surface of the crystallizer is 2000-2800L/min; the insertion depth of the water gap of the continuous casting crystallizer is controlled to be 100-160 mm; the taper of the narrow surface of the crystallizer is 1.05 to 1.25.
2. The low-carbon high-nitrogen tinned substrate according to claim 1, wherein the steel grade of the substrate is composed of the following elements in percentage by mass:
C：0.03～0.10％，0<Si≤0.7％，0<mn is less than or equal to 0.8%, S is less than or equal to 0.016%, P is less than or equal to 0.020%, al:0.01 to 0.08 percent, N: 0.010-0.018%, and Mn/S is more than or equal to 50, 2X 10 -8 ≤[Al]·[N]The product is less than or equal to 20 multiplied by 10 -8 The balance being Fe and unavoidable impurities.
3. A steel plate blank continuous casting production method of a low-carbon high-nitrogen tin-plated substrate is characterized in that in the continuous casting process,
dividing a continuous casting secondary cooling zone into sections 0-8 along the length direction of a casting machine, and adding 9 sections in total;
the second cooling area 0 and the No. 1 are controlled based on a pull-speed water meter, the average pull-speed is controlled to be 1.0-1.8 m/min, and the specific water quantity is controlled to be 1.2-1.6L/kg;
the second cooling zone 2-8 adopts target temperature control, and the target temperature is 650-750 ℃;
the secondary cooling electromagnetic stirring current is 1200-2200A, and the stirring frequency is 2.0-4.0 Hz; the superheat degree of the molten steel in the tundish is controlled to be 10-50 ℃; the water quantity of the wide surface of the crystallizer is 2000-2800L/min; the insertion depth of the water gap of the continuous casting crystallizer is controlled to be 100-160 mm; the taper of the narrow surface of the crystallizer is 1.05 to 1.25.
4. The continuous casting process for a steel slab of a low-carbon high-nitrogen tin-plated substrate according to claim 3, wherein the thickness of the slab cross section x the slab width is controlled to be (200 to 300) mm x (800 to 1650) mm in the slab continuous casting step.
5. The continuous casting production method of the steel plate blank of the low-carbon high-nitrogen tinned substrate according to claim 3, wherein the second cooling zone 0 and the first cooling zone 1 are controlled based on a pull-speed water meter, the average pull speed is controlled to be 1.2-1.70 m/min, and the specific water quantity is controlled to be 1.3-1.5L/kg.
6. The continuous casting production method of the steel plate blank of the low-carbon high-nitrogen tinned substrate according to claim 5, wherein the second cooling zone 2-8 sections are controlled by target temperature, and the target temperature is 675-750 ℃.
7. The continuous casting production method of the steel plate blank of the low-carbon high-nitrogen tinned substrate according to claim 3, wherein the secondary cooling electromagnetic stirring current is 1400-2000A and the stirring frequency is 2.5-3.5 Hz.
8. The continuous casting production method of the steel plate blank of the low-carbon high-nitrogen tinned substrate according to claim 3, wherein the superheat degree of molten steel in the tundish is controlled to be 20-40 ℃.
9. The continuous casting production method of the steel plate blank of the low-carbon high-nitrogen tinned substrate according to claim 3, wherein the water quantity of the wide surface of the crystallizer is 2200-2500L/min.
10. The continuous casting production method of the steel plate blank of the low-carbon high-nitrogen tinned substrate according to claim 3, wherein the water gap insertion depth of the continuous casting crystallizer is controlled to be 120-150 mm.
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| JP2002266016A (en) * | 2001-01-05 | 2002-09-18 | Kawasaki Steel Corp | Method for producing rolling stock for dead soft steel sheet having high age hardenability |
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