Method for preparing anti-burnt-on roll coating and surface texture integrated for silicon steel normalizing furnace

Abstract

The application discloses a method for integrally preparing an anti-nodular furnace roller coating and a surface texture for a silicon steel normalizing furnace, which is suitable for a silicon steel normalizing and pickling unit normalizing furnace with a working temperature of less than or equal to 1150 DEG C and belongs to the field of silicon steel production. The method adopts a material plus annular texture mode to inhibit nodulation, develops a laser cladding Ni-based alloy coating, and integrates the coating and the texture in metallurgy to avoid secondary processing defects. The laser cladding synchronously completes working layer and texture forming, has high bonding strength, no interface micro-cracks, and no peeling phenomenon after high-temperature circulation. Through four core links of high-temperature chemical reaction, solid solution strengthening, grain boundary regulation and oxidation film modification, the performance of the coating is comprehensively improved. Experimental verification shows that the coating is stable and has obvious anti-nodular effect in the production process of the normalizing furnace at 1150 DEG C, and is significantly better than the performance of an existing coating.

Description

Technical Field

[0001] This invention belongs to the field of silicon steel production, and particularly relates to an integrated preparation method of coating and surface texture for anti-nodulation furnace rollers for silicon steel normalizing furnaces. Background Technology

[0002] As a core component of the high-temperature conveying system for silicon steel strip, the furnace rollers of the normalizing furnace must operate under harsh conditions below 1150℃ and in a water-nitrogen mixed atmosphere for extended periods. The normalizing furnace uses natural gas for open-flame heating. Natural gas combustion primarily produces carbon dioxide and water vapor, but incomplete combustion may also produce carbon monoxide and trace amounts of hydrogen. These gases, along with trace amounts of oxygen present in the furnace, create a complex redox environment. Under this complex environment, oxides such as FeO, Fe2O3, Fe3O4, and FeCr2O4 are formed. These low-melting-point oxides adhere to the furnace rollers, eventually accumulating to form nodules. These nodules not only severely impact the stability of the production line and product quality but also lead to reduced production capacity, product scrap, and energy waste. This problem has become a major bottleneck in the normalizing and pickling process, causing significant economic losses and profoundly affecting the company's operations and development.

[0003] In existing technologies, furnace roller anti-nodulation solutions are mainly divided into three categories: One method is single-coating reinforcement, such as laser cladding of nickel-based tungsten carbide and plasma spraying of Al2O3-TiO2 coating (such as US6841221B2). However, this method only relies on the coating composition to improve wear resistance without optimizing the surface morphology. The large contact area between the oxide scale and the coating still poses a risk of nodule formation and is prone to oxidation and peeling at high temperatures. Second, post-coating textures, such as laser-etched textures and electrical discharge machining of micro-pits (e.g., CN114481266B, JP2021-121567A), are prone to damaging the interface between the coating and the substrate during secondary processing, resulting in micro-cracks. Under high-temperature cycling conditions, the risk of coating peeling is significantly increased, and the bonding strength is generally lower than 45MPa. Thirdly, there are textured cladding coatings, such as laser cladding mesh metal-based ceramic coatings (e.g., CN115537806A). However, the texture is a common structure such as mesh and herringbone, which is not suitable for the rotating conveyor conditions of the furnace roller. Moreover, the ceramic phase is mostly tungsten carbide and chromium carbide, and the nodulation inhibition effect is limited at 1150℃ (nodulation rate ≥40%).

[0004] Deficiencies of existing technology: Existing technologies have not optimized the matching relationship between coating composition and texture parameters for the operating conditions of silicon steel normalizing furnaces. Either the coating lacks sufficient high-temperature resistance, or the texture easily accumulates oxide scale, accelerating nodulation. Furthermore, most solutions lack quantitative coating performance data and operating condition adaptation verification. Therefore, there is an urgent need to develop an integrated preparation method that is compatible with silicon steel normalizing furnaces below 1150℃, where coating and texture work synergistically to prevent nodulation, and where performance data is verifiable.

[0005] References (such as patents / papers / standards)

[0006] CN101654377A, CN101838767A, CN102650028A, CN103374693A, CN104046979A, CN110747465B, CN111270066B, CN115283669A Summary of the Invention

[0007] To address the technical shortcomings of existing technologies, such as poor stability of coating and texture bonding, insufficient texture adaptability, and limited high-temperature anti-nodulation effect, this paper proposes a method for preparing a special anti-nodulation furnace roller for silicon steel normalizing furnaces, based on verified coating experimental data. By integrating a specific ratio of ceramic coating and annular texture through laser cladding, a synergistic effect is achieved on the coating's temperature resistance, the texture's chip removal performance, and its adaptability to operating conditions, significantly reducing the nodulation rate and extending the service life of the furnace roller.

[0008] A method for integrating anti-nodulation furnace roller coating and surface texture in silicon steel normalizing furnaces, applicable to normalizing furnaces in silicon steel normalizing and pickling units with operating temperatures ≤1150℃, characterized by the following preparation steps: (1) Pretreatment of furnace roll substrate: Centrifugal casting high temperature resistant alloy Cr33Ni50W16 furnace roll substrate is selected and machined to the target diameter by lathe, with surface roughness Ra=3.2-6.3μm; (2) Preparation of cladding powder: The powder is dried at 110℃ for 2.5h to remove moisture. The specific formula is as follows: the weight percentage is Cr 17.5-18.1%, Al 3-3.6%, Co 4-4.6%, Y 1-1.6%, and the balance is Ni; the powder particle size is 40-70μm; (3) Laser cladding integrated forming coating and ring texture: (4) Preheating treatment: The furnace roller substrate is heated and kept warm in a heating furnace to reduce the temperature difference stress between the substrate and the coating; (5) Underlayer cladding: A fiber laser is used to scan, feed powder, and coat under argon protection; the thickness of the underlayer after cladding is H1, with H1 ranging from 290 to 310 μm. The textured area and the coating are metallurgically integrated, with no interface cracks. (6) Texture layer cladding: The same fiber laser is used for scanning, powder feeding, and coating under argon protection; the coating overlap rate is adjusted by adjusting the laser transverse speed to form an arc-shaped ring texture. (7) Arc-shaped ring texture: forming a closed ring arc protrusion adapted to the rotation condition of the furnace roller; (8) Low-temperature tempering to relieve stress: After the cladding is completed, the furnace roller is placed in a heat treatment furnace for low-temperature tempering and cooled to room temperature with the furnace to avoid coating cracking under high-temperature conditions. (9) Coating polishing treatment: A two-stage polishing process is adopted to match the ring texture morphology: coarse polishing uses a soft steel wire wheel, and fine polishing uses a wool wheel with chromium oxide polishing agent. After polishing, the surface texture of the furnace roller is smooth, without oxide scale or residual dead corners. (10) On-machine adaptation and debugging: The prepared furnace rollers are loaded into the silicon steel normalizing furnace, with nitrogen as the protective gas. The rotation speed is set to match the running speed of the strip according to the thermal expansion coefficient of the strip and the diameter of the furnace rollers.

[0009] Furthermore, the heating furnace temperature in step (4) is 210-240℃, and the temperature is maintained for 70-90 minutes.

[0010] Furthermore, the process parameters for the underlayer cladding in step (5) are: power 1.8-1.9kW, scanning speed 27-30mm / s, powder feeding amount 5-7g / min, and argon protection flow rate 20L / min.

[0011] Furthermore, the process parameters for the cladding of the textured layer in step (6) are: power 1.8-1.9kW, scanning speed 27-30mm / s, powder feeding amount 5-7g / min, and argon protection flow rate 20L / min.

[0012] Further, the arc-shaped annular texture parameters in step (7) are: protrusion width W, ranging from 4 to 5 mm; groove depth H2, ranging from 0.2 to 0.3 mm; and adjacent protrusion spacing L, ranging from 5 to 6 mm.

[0013] Furthermore, the low-temperature tempering described in step (8) is performed at a tempering temperature of 280°C for 2-3 hours.

[0014] Further, the coating polishing process described in step (9) is as follows: rough polishing speed 1400 r / min, pressure 0.25 MPa, to remove burrs from the texture edge; fine polishing speed 2000 r / min, pressure 0.08 MPa.

[0015] This invention employs a combination of material composition and surface texture morphology to suppress nodule formation. It relates to a coating for furnace rollers in normalizing furnaces used in silicon steel production, effectively addressing the nodule formation problem in the normalizing process. The coating operates at temperatures exceeding 1150℃. Its core innovation lies in: 1. Targeted innovation in coating composition: A Ni-based alloy coating for laser cladding was developed. Utilizing the in-situ modification mechanism of the rare earth element yttrium, the coating performance was comprehensively improved through four core processes: chemical reaction at high temperature, solid solution strengthening, grain boundary regulation, and oxide film modification. Experimental verification showed that the coating was stable and had a significant anti-nodulation effect during normalizing furnace production at 1150℃, which was significantly better than the performance of existing coatings.

[0016] 2. Texture structure adapted to working conditions and depth: The existing mesh and straight texture (such as CN114481266B, US20100116380A1) are replaced by a ring texture. The surface texture reduces the adhesion of nodules, thereby avoiding nodule accumulation.

[0017] 3. Integrated molding avoids secondary processing defects: Laser cladding simultaneously completes the forming of the working layer and the texture, which is different from "post-coating texture processing" (such as JP2021-121567A). The coating and texture are metallurgically integrated structures with high bonding strength, no interface micro-cracks, and no peeling after high-temperature cycling.

[0018] 4. Full-process operating condition binding: From matrix material, powder ratio, process parameters to on-machine debugging, all are limited to silicon steel normalizing furnaces below 1150℃, which is different from general furnace roller strengthening solutions (such as EP4589026A1). The technical solution is highly targeted and the protection scope is clear.

[0019] Beneficial effects of the technical solution of this invention

[0020] 1. The rate of furnace roller nodule formation has decreased significantly, from once every two weeks to more than once every two months, significantly improving the production efficiency of silicon steel production enterprises, with a single unit increasing annual output value by 4.6 million yuan; 2. The amount of products with reduced quality due to furnace roller nodule formation has decreased from 100-150 tons / month to less than 20 tons / month, resulting in an annual reduction of economic losses of over 1.9 million yuan for a single production line.

[0021] 3. Nodule formation on the furnace rolls of silicon steel normalizing furnaces is an industry-wide problem. Currently, there are more than 50 silicon steel normalizing production lines with such equipment installed. If it is widely adopted, the economic and social benefits will be significant. Attached Figure Description

[0022] Figure 1 This is a powder SEM image of the present invention; Figure 2 This is a particle size distribution diagram of the powder of the present invention; Figure 3 Metallographic image of the coating; Figure 4 This is a hardness chart of the coating. Figure 5 For process flow diagram; Figure 6 This is a diagram showing the state after cladding; Figure 7 Hardness distribution curves of cross sections after cladding with different compositions; Figure 8 The outline of the furnace roll is shown, with the surface texture distributed in a mirror image with the center of the roll as the central axis. Figure 9 This is a detailed view of the surface texture of the furnace roller, showing the angle A between the texture and the centerline; Figure 10 This is a cross-sectional view of the surface texture of the furnace rollers. Detailed Implementation

[0023] The alloy composition of the furnace rollers is Cr33Ni50W16:

[0024] Example 1, the specific preparation steps are as follows: (1) Pretreatment of furnace roll substrate: Centrifugal casting high temperature resistant alloy Cr33Ni50W16 furnace roll substrate is selected and machined to the target diameter by lathe, with surface roughness Ra=3.2-6.3μm.

[0025] (2) Preparation of cladding powder: The powder is dried at 110℃ for 2.5h to remove moisture. The specific formula is as follows: the weight percentage is Cr 17.5-18.1%, Al 3-3.6%, Co 4-4.6%, Y 1-1.6%, and the balance is Ni; the powder particle size is 40-70μm; (3) Laser cladding integrated forming coating and ring texture: (4) Preheating treatment: Place the furnace roller substrate in a heating furnace at a temperature of 210-240℃ and keep it at that temperature for 70-90 minutes to reduce the temperature difference stress between the substrate and the coating.

[0026] (5) Underlayer cladding: A fiber laser is used with the following process parameters: power 1.8-1.9kW, scanning speed 27-30mm / s, powder feed rate 5-7g / min, and argon protection flow rate 20L / min. The thickness of the underlayer after cladding is H1, with H1 valued at 290-310μm. The textured area and the coating form a metallurgically integrated structure without interface cracks. (6) Texture layer cladding: The process parameters are: power 1.8-1.9kW, scanning speed 27-30mm / s, powder feed rate 5-7g / min, and argon protection flow rate 20L / min. The coating overlap rate is adjusted by adjusting the laser transverse speed to form an arc-shaped ring texture. (7) Arc-shaped annular texture parameters: closed annular arc protrusions adapted to the rotation conditions of the furnace rollers, with protrusion width W ranging from 4 to 5 mm; groove depth H2 ranging from 0.2 to 0.3 mm; and adjacent protrusion spacing L ranging from 5 to 6 mm.

[0027] (8) Low-temperature tempering to relieve stress: After the cladding is completed, the furnace roller is placed in the heat treatment furnace and tempered at 280°C for 2.5 hours. Then, it is cooled to room temperature with the furnace to avoid cracking of the coating under high temperature conditions.

[0028] (9) Coating polishing treatment: A two-stage polishing process is adopted to adapt to the annular texture morphology: coarse polishing uses a soft steel wire wheel with a speed of 1400 r / min and a pressure of 0.25 MPa to remove burrs on the edge of the texture; fine polishing uses a wool wheel with chromium oxide polishing agent with a speed of 2000 r / min and a pressure of 0.08 MPa; after polishing, the surface of the furnace roller has a smooth texture, no oxide scale and no residual dead corners.

[0029] (10) On-machine adaptation and debugging: The prepared furnace rollers are loaded into the silicon steel normalizing furnace, with nitrogen as the protective gas. The rotation speed is set to match the running speed of the strip according to the thermal expansion coefficient of the strip and the diameter of the furnace rollers.

[0030] Example 2, the specific preparation steps are as follows: The conditions for steps (1), (2), and (3) are the same as those in Example 1, except that steps (4), (5), (6), (7), (8), and (9) are changed.

[0031] (1) Pretreatment of furnace roll substrate: Centrifugal casting high temperature resistant alloy Cr33Ni50W16 furnace roll substrate is selected and machined to the target diameter by lathe, with surface roughness Ra=3.2-6.3μm.

[0032] (2) Preparation of cladding powder: The powder is dried at 110℃ for 2.5h to remove moisture. The specific formula is as follows: the weight percentage is Cr 17.5-18.1%, Al 3-3.6%, Co 4-4.6%, Y 1-1.6%, and the balance is Ni; the powder particle size is 40-70μm; (3) Laser cladding integrated forming coating and ring texture: (4) Preheating treatment: Place the furnace roller substrate in a heating furnace at a temperature of 210-240℃ and keep it at that temperature for 70-90 minutes to reduce the temperature difference stress between the substrate and the coating.

[0033] (5) Underlayer cladding: A fiber laser is used with the following process parameters: power 1.8-1.9kW, scanning speed 27-30mm / s, powder feed rate 5-7g / min, and argon protection flow rate 20L / min. The thickness of the underlayer after cladding is H1, with H1 valued at 290-310μm. The textured area and the coating are metallurgically integrated, with no interface cracks.

[0034] (6) Texture layer cladding: The process parameters are power 1.8-1.9kW, scanning speed 27-30mm / s, powder feeding amount 5-7g / min, and argon protection flow rate 20L / min; the coating overlap rate is adjusted by adjusting the laser transverse speed to form an arc-shaped ring texture. (7) Arc-shaped annular texture parameters: closed annular arc protrusions adapted to the rotation conditions of the furnace rollers, with protrusion width W ranging from 4 to 5 mm; groove depth H2 ranging from 0.2 to 0.3 mm; and adjacent protrusion spacing L ranging from 5 to 6 mm.

[0035] (8) Low-temperature tempering to relieve stress: After the cladding is completed, the furnace roller is placed in the heat treatment furnace and tempered at 280°C for 2.5 hours. Then, it is cooled to room temperature with the furnace to avoid cracking of the coating under high temperature conditions.

[0036] (9) Coating polishing treatment: A two-stage polishing process is adopted to adapt to the annular texture morphology: coarse polishing uses a soft steel wire wheel with a speed of 1400 r / min and a pressure of 0.25 MPa to remove burrs on the edge of the texture; fine polishing uses a wool wheel with chromium oxide polishing agent with a speed of 2000 r / min and a pressure of 0.08 MPa; after polishing, the surface of the furnace roller has a smooth texture, no oxide scale and no residual dead corners.

[0037] (10) On-machine adaptation and debugging: The prepared furnace rollers are loaded into the silicon steel normalizing furnace, with nitrogen as the protective gas. The rotation speed is set to match the running speed of the strip according to the thermal expansion coefficient of the strip and the diameter of the furnace rollers.

[0038] Example 3

[0039] The specific preparation steps are as follows: The conditions for steps (1), (2), and (3) are the same as those in Example 1, except that steps (4), (5), (6), (7), (8), and (9) are changed.

[0040] (1) Pretreatment of furnace roll substrate: Centrifugal casting high temperature resistant alloy Cr33Ni50W16 furnace roll substrate is selected and machined to the target diameter by lathe. The surface roughness Ra = 3.2 - 6.3μm.

[0041] (2) Preparation of cladding powder: The powder is dried at 110℃ for 2.5h to remove moisture. The specific formula is as follows: the weight percentage is Cr17.5-18.1%, Al3-3.6%, Co4-4.6%, Y1-1.6%, and the balance is Ni; the powder particle size is 40-70μm; (3) Laser cladding integrated forming coating and ring texture: (4) Preheating treatment: Place the furnace roller substrate in a heating furnace at a temperature of 200-230℃ and keep it at that temperature for 60-80 minutes to reduce the temperature difference stress between the substrate and the coating.

[0042] (5) Underlayer cladding: A fiber laser is used with the following process parameters: power 1.7 - 1.85kW, scanning speed 25 - 28mm / s, powder feed rate 4 - 6g / min, and argon protection flow rate 18L / min. The thickness of the underlayer after cladding is H1, with H1 valued at 280 - 300μm. The textured area and the coating are metallurgically integrated, with no interface cracks.

[0043] (6) Texture layer cladding: The process parameters are power 1.7 - 1.85kW, scanning speed 25 - 28mm / s, powder feeding amount 4 - 6g / min, and argon protection flow rate 18L / min; the coating overlap rate is adjusted by adjusting the laser transverse speed to form an arc-shaped ring texture. (7) Arc-shaped annular texture parameters: closed annular arc protrusions adapted to the rotation conditions of the furnace rollers, with protrusion width W ranging from 4.2 to 4.8 mm; groove depth H2 ranging from 0.22 to 0.28 mm; and adjacent protrusion spacing L ranging from 5.2 to 5.8 mm.

[0044] (8) Low-temperature tempering to relieve stress: After the cladding is completed, the furnace roller is placed in the heat treatment furnace and tempered at 270°C for 2 hours. Then, it is cooled to room temperature with the furnace to avoid cracking of the coating under high temperature conditions.

[0045] (9) Coating polishing treatment: A two-stage polishing process is adopted to adapt to the annular texture morphology: coarse polishing uses a soft steel wire wheel with a speed of 1300 r / min and a pressure of 0.22 MPa to remove burrs on the edge of the texture; fine polishing uses a wool wheel with chromium oxide polishing agent with a speed of 1900 r / min and a pressure of 0.07 MPa; after polishing, the surface of the furnace roller is smooth, without oxide scale and residual dead corners.

[0046] (10) On-machine adaptation and debugging: The prepared furnace rollers are loaded into the silicon steel normalizing furnace, with nitrogen as the protective gas. The rotation speed is set to match the running speed of the strip according to the thermal expansion coefficient of the strip and the diameter of the furnace rollers.

[0047]

Claims

1. A method for integrating anti-nodulation furnace roller coating and surface texture for silicon steel normalizing furnaces, applicable to normalizing furnaces in silicon steel normalizing and pickling units with operating temperatures ≤1150℃, characterized in that, The preparation steps are as follows: (1) Pretreatment of furnace roll substrate: Centrifugal casting high temperature resistant alloy Cr33Ni50W16 furnace roll substrate is selected and machined to the target diameter by lathe, with surface roughness Ra=3.2-6.3μm; (2) Preparation of cladding powder: The powder is dried at 110℃ for 2.5h to remove moisture. The specific formula is as follows: the weight percentage is Cr 17.5-18.1%, Al 3-3.6%, Co 4-4.6%, Y 1-1.6%, and the balance is Ni; the powder particle size is 40-70μm; (3) Laser cladding integrated forming coating and ring texture: (4) Preheating treatment: The furnace roller substrate is heated and kept warm in a heating furnace to reduce the temperature difference stress between the substrate and the coating; (5) Underlayer cladding: A fiber laser is used to scan, feed powder, and coat under argon protection; the thickness of the underlayer after cladding is H1, with H1 ranging from 290 to 310 μm. The textured area and the coating are metallurgically integrated, with no interface cracks. (6) Texture layer cladding: The same fiber laser is used for scanning, powder feeding, and coating under argon protection; the coating overlap rate is adjusted by adjusting the laser transverse speed to form an arc-shaped ring texture. (7) Arc-shaped ring texture: forming a closed ring arc protrusion adapted to the rotation condition of the furnace roller; (8) Low-temperature tempering to relieve stress: After the cladding is completed, the furnace roller is placed in a heat treatment furnace for low-temperature tempering and cooled to room temperature with the furnace to avoid coating cracking under high-temperature conditions. (9) Coating polishing treatment: A two-stage polishing process is adopted to match the ring texture morphology: coarse polishing uses a soft steel wire wheel, and fine polishing uses a wool wheel with chromium oxide polishing agent. After polishing, the surface texture of the furnace roller is smooth, without oxide scale or residual dead corners. (10) On-machine adaptation and debugging: The prepared furnace rollers are loaded into the silicon steel normalizing furnace, with nitrogen as the protective gas. The rotation speed is set to match the running speed of the strip according to the thermal expansion coefficient of the strip and the diameter of the furnace rollers.

2. The method for integrating anti-nodulation furnace roller coating and surface texture for silicon steel normalizing furnaces according to claim 1, characterized in that, The heating furnace temperature in step (4) is 210-240℃, and the temperature is maintained for 70-90 minutes.

3. The method for integrating anti-nodulation furnace roller coating and surface texture for silicon steel normalizing furnaces according to claim 1, characterized in that, The process parameters for the underlayer cladding in step (5) are: power 1.8-1.9kW, scanning speed 27-30mm / s, powder feeding amount 5-7g / min, and argon protection flow rate 20L / min.

4. The method for integrating anti-nodulation furnace roller coating and surface texture for silicon steel normalizing furnaces according to claim 1, characterized in that, The process parameters for the textural layer cladding in step (6) are: power 1.8-1.9kW, scanning speed 27-30mm / s, powder feeding rate 5-7g / min, and argon protection flow rate 20L / min.

5. The method for integrating anti-nodulation furnace roller coating and surface texture for silicon steel normalizing furnaces according to claim 1, characterized in that, The parameters of the arc-shaped annular texture in step (7) are: the width of the protrusion W, which ranges from 4 to 5 mm; the groove depth H2, which ranges from 0.2 to 0.3 mm; and the distance between adjacent protrusions L, which ranges from 5 to 6 mm.

6. The method for integrating anti-nodulation furnace roller coating and surface texture for silicon steel normalizing furnaces according to claim 1, characterized in that, The low-temperature tempering described in step (8) is performed at a tempering temperature of 280°C for 2-3 hours.

7. The method for integrating anti-nodulation furnace roller coating and surface texture for silicon steel normalizing furnaces according to claim 1, characterized in that, The coating polishing process described in step (9) is as follows: rough polishing speed is 1400 r / min, pressure is 0.25 MPa, and burrs on the texture edge are removed; fine polishing speed is 2000 r / min, pressure is 0.08 MPa.

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