Method for determining the feeding parameters of steel strip in the continuous casting process of super austenitic stainless steel

Abstract

This invention discloses a method for determining the feeding parameters of steel strip during the continuous casting process of super austenitic stainless steel, relating to the field of super austenitic stainless steel production. The method includes obtaining the operating parameters and molten steel properties during the feeding process of the continuous casting crystallizer to produce super austenitic stainless steel slabs; presetting the steel strip width, thickness, and feeding speed based on the operating parameters, molten steel properties, molten steel-strip phase transformation heat transfer theory, and cooling water-molten steel heat transfer theory; presetting the steel strip oscillation frequency and amplitude based on the fine-grained zone width regression model, operating parameters, and molten steel properties; determining whether the current preset parameters satisfy the fine-grained zone height regression model; if so, determining the current preset parameters as the final steel strip feeding parameters. This invention can accurately match the steel strip feeding parameters, improving the solidification quality of super austenitic stainless steel continuously cast slabs.

Description

Technical Field

[0001] This invention relates to the field of super austenitic stainless steel production, and in particular to a method for determining the feeding parameters of steel strip during the continuous casting process of super austenitic stainless steel. Background Technology

[0002] Super austenitic stainless steel possesses significantly greater strength and corrosion resistance than ordinary austenitic stainless steel, making it widely used in highly corrosive environments such as marine engineering and petrochemicals. However, super austenitic stainless steel contains a large number of alloying elements, which continuously accumulate in the molten steel during continuous casting, exacerbating segregation in the center of the continuously cast slab and causing intractable inclusion and cracking problems.

[0003] Feeding steel strip into the continuous casting mold can change the traditional solidification method from the surface to the interior in continuous casting. The cold steel strip promotes the solidification of the surrounding molten steel, improving the solidification quality of the continuously cast billet. This method has already been applied in the production of super austenitic stainless steel. In the process of producing super austenitic stainless steel continuously cast billets by feeding steel strip into the continuous casting mold, the feeding parameters of the steel strip are key to controlling the improvement of the solidification quality of the billet. A mismatch between the feeding parameters and the continuous casting machine operating conditions will result in unmelted steel strip remaining in the billet, increasing the risk of cracking and deteriorating the internal quality of the billet. Conversely, overly conservative feeding parameters will limit the cooling effect of the steel strip.

[0004] Patents CN112059132A ("A Method for Improving the Solidification Quality of Cast Billets by Feeding Boron, Magnesium, and Rare Earth Stainless Steel Strip into a Crystallizer") and CN115519082A ("A Method for Suppressing the Segregation of Alloy Elements in the Center of Super Austenitic Stainless Steel Billets") both introduce the application of crystallizer strip feeding technology in the production of super austenitic stainless steel. However, neither of these patents can accurately match the strip feeding parameters. Patent CN105033216A ("A Method for Determining Process Parameters of Crystallizer Strip Feeding in Thick Slab Continuous Casting") provides a method for determining the strip size and feeding speed in the production of ordinary steel using crystallizer strip feeding, but this method is not applicable to super austenitic stainless steel, and the strip oscillation parameters need further matching with the strip feeding amount. Summary of the Invention

[0005] The purpose of this invention is to provide a method for determining the feeding parameters of steel strip during the continuous casting of super austenitic stainless steel, which can accurately match the feeding parameters of steel strip and improve the solidification quality of super austenitic stainless steel slabs.

[0006] To achieve the above objectives, the present invention provides the following solution:

[0007] A method for determining the feeding parameters of steel strip in the continuous casting process of super austenitic stainless steel includes:

[0008] The process of producing super austenitic stainless steel slabs in a continuous casting crystallizer by feeding strip is used to obtain the operating parameters and molten steel properties. The operating parameters include: billet drawing speed, molten steel superheat, crystallizer size, secondary cooling zone length, liquid core length, crystallizer cooling water flow rate, crystallizer cooling water inlet and outlet temperatures, secondary cooling zone cooling water temperature and spray density, and ambient temperature. The molten steel properties include: molten steel specific heat capacity, molten steel density, molten steel liquidus temperature, and molten steel latent heat.

[0009] Based on the working parameters, the physical properties of molten steel, the heat transfer theory of molten steel to strip phase change and the heat transfer theory of cooling water to molten steel, the strip width, strip thickness and feeding speed are preset.

[0010] Based on the fine grain region width regression model, operating parameters, and molten steel properties, the steel strip oscillation frequency and steel strip amplitude are preset;

[0011] Determine whether the current preset parameters satisfy the fine grain region height regression model. If they do, then determine the current preset parameters as the final steel strip feeding parameters. If they do not, return to the step of presetting the steel strip size, feeding speed, and steel strip thickness based on the operating condition parameters, molten steel property parameters, molten steel-steel strip phase change heat transfer theory, and cooling water-molten steel heat transfer theory. The current preset parameters include: preset steel strip size, preset feeding speed, preset steel strip oscillation frequency, and preset steel strip amplitude.

[0012] Optionally, the steel strip is vertically fed into the molten steel at a distance of 600mm to 650mm from the submersible nozzle. The width of the steel strip satisfies: 0 < w < 0.1W; the thickness of the steel strip satisfies: 0 < d < 0.3w; the amplitude of the steel strip satisfies: A < 2mm; and the oscillation frequency of the steel strip satisfies: f < 300Hz.

[0013] Where w is the width of the steel strip (mm); d is the thickness of the steel strip (mm); W is the length of the crystallizer (mm); f is the oscillation frequency of the steel strip (Hz); and A is the amplitude of the steel strip (mm).

[0014] Optionally, the step of presetting the steel strip size, feeding speed, and steel strip thickness based on operating parameters, molten steel properties, molten steel-steel strip phase change heat transfer theory, and cooling water-molten steel heat transfer theory specifically includes:

[0015]

[0016] Where v is the belt feed speed, m / s; c p ρ is the specific heat capacity of molten steel, J (kg·℃); ρ is the density of molten steel, kg / m³ 3 D is the width of the crystallizer, mm; V is the billet drawing speed, m / s; ΔT is the superheat of the molten steel, °C; Q w The flow rate of the cooling water for the crystallizer is kg / s; c wΔt represents the specific heat capacity of cooling water, in J (kg·℃); w The temperature difference between the inlet and outlet of the cooling water for the crystallizer, in °C; W w The density of cooling water spray in the secondary cooling zone, L(m 2 ·s); H sec The height of the second cooling zone is in mm; T w The temperature of the cooling water in the secondary cooling zone is ℃; T b The ambient temperature is in °C; T l ν is the liquidus temperature of molten steel, °C; L is the latent heat of molten steel, J / kg.

[0017] Optionally, the step of determining the fine-grained region width regression model and presetting the strip oscillation frequency and amplitude based on the fine-grained region width regression model, operating parameters, and molten steel properties specifically includes:

[0018] 650.42+2.75f+826.98A-9.12ΔT≥0.4W

[0019] Optionally, determining whether the current preset parameters satisfy the fine-grained region height regression model specifically includes:

[0020] 0.0013H mold ≤-32.1699+106.3707v-0.08353ΔT+0.32396w+3.70091d-0.0477f-14.4123A≤0.0007H;

[0021] Among them, H mold H represents the height of the crystallizer, in mm; H represents the length of the liquid core, in mm.

[0022] Optionally, the continuous casting machine is a vertical slab continuous casting machine.

[0023] Optionally, the billet pulling speed is 0.005 to 0.0067 m / s; the crystallizer length W ranges from 1200 mm to 1500 mm; the crystallizer width D ranges from 100 to 250 mm; and the crystallizer height is 700 to 1000 mm.

[0024] According to specific embodiments provided by the present invention, the present invention discloses the following technical effects:

[0025] The present invention provides a method for determining the feeding parameters of steel strip in the continuous casting process of super austenitic stainless steel. The method collects the operating conditions and physical properties of molten steel during the continuous casting process of super austenitic stainless steel slab, and determines the feeding parameters of the super austenitic stainless steel slab production process based on the heat transfer theory of molten steel-steel strip phase transformation, the heat transfer theory of cooling water-molten steel, the regression model of fine grain width, and the regression model of fine grain height, so as to ensure the quality of super austenitic stainless steel slab. Attached Figure Description

[0026] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0027] Figure 1 This is a schematic flowchart illustrating a method for determining the feeding parameters of steel strip during the continuous casting of super austenitic stainless steel, as provided by the present invention. Detailed Implementation

[0028] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0029] The purpose of this invention is to provide a method for determining the feeding parameters of steel strip during the continuous casting of super austenitic stainless steel, which can accurately match the feeding parameters of steel strip and improve the solidification quality of super austenitic stainless steel slabs.

[0030] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0031] like Figure 1 As shown, the method for determining the feeding parameters of steel strip in the continuous casting process of super austenitic stainless steel provided by the present invention includes:

[0032] S101, Obtain the operating parameters and molten steel properties during the continuous casting process of feeding the strip into a super austenitic stainless steel slab; the operating parameters include: billet pulling speed, molten steel superheat, crystallizer size, secondary cooling zone length, liquid core length, crystallizer cooling water flow rate, crystallizer cooling water inlet and outlet temperatures, secondary cooling zone cooling water temperature and spray density, and ambient temperature; the molten steel properties include: molten steel specific heat capacity, molten steel density, molten steel liquidus temperature, and molten steel latent heat.

[0033] The steel strip is vertically fed into the molten steel at a distance of 600mm to 650mm from the submersible nozzle. The width of the steel strip satisfies: 0 < w < 0.1W; the thickness of the steel strip satisfies: 0 < d < 0.3w; the amplitude of the steel strip satisfies: A < 2mm; and the oscillation frequency of the steel strip satisfies: f < 300Hz.

[0034] Where w is the width of the steel strip (mm); d is the thickness of the steel strip (mm); W is the length of the crystallizer (mm); f is the oscillation frequency of the steel strip (Hz); and A is the amplitude of the steel strip (mm).

[0035] The continuous casting machine is a vertical slab continuous casting machine.

[0036] The billet pulling speed is 0.005m / s to 0.0067m / s; the crystallizer length W ranges from 1200mm to 1500mm; the crystallizer width D ranges from 100mm to 250mm; and the crystallizer height ranges from 700mm to 1000mm.

[0037] S102, based on working parameters, molten steel properties, molten steel-strip phase change heat transfer theory, and cooling water-molten steel heat transfer theory, preset the strip width, strip thickness, and feeding speed.

[0038] S102 specifically includes:

[0039]

[0040] Where v is the belt feed speed, m / s; c p ρ is the specific heat capacity of molten steel, J / (kg·℃); ρ is the density of molten steel, kg / m³ 3 D is the width of the crystallizer, mm; V is the billet drawing speed, m / s; ΔT is the superheat of the molten steel, °C; Q w The flow rate of the cooling water for the crystallizer is kg / s; c w Δt represents the specific heat capacity of cooling water, in J (kg·℃); w The temperature difference between the inlet and outlet of the cooling water for the crystallizer, in °C; W w The cooling water spray density in the secondary cooling zone is expressed in L / (m³). 2 ·s); H sec The height of the second cooling zone is in mm; T w The temperature of the cooling water in the secondary cooling zone is ℃; T b The ambient temperature is in °C; T l ν is the liquidus temperature of molten steel, °C; L is the latent heat of molten steel, J / kg.

[0041] S103, based on the fine grain region width regression model, operating parameters, and molten steel property parameters, preset the steel strip oscillation frequency and steel strip amplitude.

[0042] S103 specifically includes:

[0043] 650.42+2.75f+826.98A-9.12ΔT≥0.4W.

[0044] S104, determine whether the current preset parameters meet the fine grain region height regression model.

[0045] S104 specifically includes:

[0046] 0.0013H mold ≤-32.1699+106.3707v-0.08353ΔT+0.32396w+3.70091d-0.0477f-14.4123A≤0.0007H.

[0047] Among them, H mold H represents the height of the crystallizer, in mm; H represents the length of the liquid core, in mm.

[0048] S105, if satisfied, then determine the current preset parameters as the final steel strip feeding parameters; if not satisfied, then return to S102; the current preset parameters include: preset steel strip size, preset feeding speed, preset steel strip oscillation frequency, and preset steel strip amplitude.

[0049] The following is an illustration through specific examples:

[0050] Super austenitic stainless steel continuous casting billets were prepared on a vertical slab casting machine with a crystallizer size of 1280mm × 160mm × 800mm. The operating parameters were: billet speed V = 0.0058 m / s, molten steel superheat ΔT = 40℃, and crystallizer cooling water flow rate Q. w =110 kg / s, temperature difference Δt between inlet and outlet of cooling water in the crystallizer w =44℃, liquid core length H=9800mm, secondary cooling zone length H sec =5800mm, cooling water spray density W in the secondary cooling zone w =1.2L / (m 2 ·s), secondary cooling zone cooling water temperature T w =25℃, ambient temperature T b =30℃.

[0051] The composition (wt%) of the molten steel is: C: 0.04, Mn: 3, Cr: 24, Ni: 22, Mo: 7, N: 0.5, Cu: 1.1, with the balance being Fe. The parameters of the molten steel calculated by thermodynamic software are: specific heat capacity of molten steel c... p =793 J / (kg·℃), molten steel density ρ = 7292 kg / m³ 3 Liquidus temperature of molten steel T l =1390℃, latent heat of molten steel L=284500J / kg.

[0052] Based on the heat transfer theory of molten steel to molten steel strip phase transformation and the heat transfer theory of cooling water to molten steel, the steel strip dimensions and feeding speed satisfy the following:

[0053]

[0054] The preset values ​​are: steel strip width w = 30mm, steel strip thickness d = 4mm, and feeding speed v = 0.2m / s.

[0055] According to the regression model for the width of the fine-grained region, the oscillation frequency and amplitude of the steel strip satisfy the following:

[0056] 650.42+2.75f+826.98A-9.12ΔT≥0.4W=512.

[0057] The preset values ​​are: steel strip oscillation frequency f = 60Hz and steel strip amplitude A = 0.5mm.

[0058] Then we have:

[0059] -32.1699+106.3707v-0.08353ΔT+0.32396w+3.70091d-0.0477f-14.4123A=0.21733<0.0013H mold =1.04.

[0060] With the steel strip width w = 30mm, steel strip thickness w = 4mm, and feeding speed v = 0.2m / s preset again, we have wdv = 24 < 25.6; with the steel strip oscillation frequency f = 60Hz and steel strip amplitude A = 0.2mm preset, we have 650.42 + 2.75f + 826.98A - 9.12ΔT = 616.02 > 512.

[0061] at this time:

[0062] -32.1699+106.3707v-0.08353ΔT+0.32396w+3.70091d-0.0477f-14.4123A=4.54102.

[0063] Because 4.54102 > 0.0013H mold =1.04 and 4.45102 < 0.0007H = 6.86.

[0064] Therefore, the final feeding parameters are determined as follows: steel strip width w = 30mm, steel strip thickness w = 4mm, feeding speed v = 0.2m / s, steel strip oscillation frequency f = 60Hz, and steel strip amplitude A = 0.2mm.

[0065] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. The same or similar parts between the various embodiments can be referred to each other.

[0066] This document uses specific examples to illustrate the principles and implementation methods of the present invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of the present invention. Furthermore, those skilled in the art will recognize that, based on the ideas of the present invention, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of the present invention.

Claims

1. A method for determining a feeding parameter of a steel strip in a continuous casting process of a super austenitic stainless steel, characterized in that, The application relates to a method for determining the feeding parameters of a superaustenitic stainless steel slab in a continuous casting process. The working condition parameters include a slab drawing speed, a liquid steel superheat degree, a crystallizer size, a secondary cooling zone length, a liquid core length, a crystallizer cooling water flow, a crystallizer cooling water inlet and outlet temperature, a secondary cooling zone cooling water temperature and spraying density and an environment temperature; the liquid steel physical property parameters include liquid steel specific heat capacity, liquid steel density, liquid steel liquidus temperature and liquid steel latent heat; The slab width, the slab thickness and the feeding speed are preset according to the working condition parameters, the liquid steel physical property parameters, a liquid steel-steel strip phase change heat transfer theory and a cooling water-liquid steel heat transfer theory; The slab oscillation frequency and the slab amplitude are preset according to a fine grain zone width regression model and the working condition parameters and the liquid steel physical property parameters; The current preset parameters are determined as the feeding parameters of the final slab if the current preset parameters satisfy the fine grain zone height regression model; if the current preset parameters do not satisfy the fine grain zone height regression model, the slab width, the slab thickness and the feeding speed are preset again according to the working condition parameters, the liquid steel physical property parameters, the liquid steel-steel strip phase change heat transfer theory and the cooling water-liquid steel heat transfer theory; the current preset parameters include preset slab dimensions, a preset feeding speed, a preset slab oscillation frequency and a preset slab amplitude; The slab oscillation frequency and the slab amplitude are preset according to a fine grain zone width regression model and the working condition parameters and the liquid steel physical property parameters; The current preset parameters are determined as the feeding parameters of the final slab if the current preset parameters satisfy the fine grain zone height regression model; if the current preset parameters do not satisfy the fine grain zone height regression model, the slab width, the slab thickness and the feeding speed are preset again according to the working condition parameters, the liquid steel physical property parameters, the liquid steel-steel strip phase change heat transfer theory and the cooling water-liquid steel heat transfer theory; the current preset parameters include preset slab dimensions, a preset feeding speed, a preset slab oscillation frequency and a preset slab amplitude; ； The continuous casting machine is a vertical slab continuous casting machine. ； wherein, is the mold height, mm; is the liquid core length, mm; is the strip speed, m / s; is the liquid steel superheat, °C; is the strip width, mm; is the strip thickness, mm; is the mold length, mm; is the strip oscillation frequency, Hz; is the strip amplitude, mm.

2. A method of determining a strand feeding parameter in a continuous casting process of a super- austenitic stainless steel according to claim 1, characterized in that, The steel belt is vertically fed into the molten steel at a distance of 600 mm to 650 mm from the submerged nozzle, and the width of the steel belt satisfies: 0 w <0.1 W ; the thickness of the steel belt satisfies ; the amplitude of the steel belt satisfies: ; and the oscillation frequency of the steel belt satisfies: .

3. A method of determining a strand feeding parameter in a continuous casting process of a super- austenitic stainless steel according to claim 2, characterized in that, ​ ； wherein, is the specific heat capacity of the steel liquid, ; is the density of the steel liquid, ; is the crystallizer width, mm; is the casting speed, m / s; is the crystallizer cooling water flow, kg / s; is the specific heat capacity of the cooling water, ; is the crystallizer cooling water inlet and outlet temperature difference, °C; is the secondary cooling zone cooling water spraying density, ; is the secondary cooling zone height, mm; is the secondary cooling zone cooling water temperature, °C; is the ambient temperature, °C; is the steel liquid liquidus temperature, °C; is the steel liquid latent heat, .

4. The method of claim 1, wherein the method is characterized by: ​ 5. The method of determining the strand feeding parameters in continuous casting of super austenitic stainless steel according to claim 4, characterized in that, The drawing speed is 0.005 m / s to 0.0067 m / s; the length of the crystallizer is The value range is 1200 mm to 1500 mm; the width of the crystallizer is The value range is 100 mm to 250 mm; the height of the crystallizer is 700 mm to 1000 mm.

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