Crystallizer copper plate and using process thereof

Abstract

The invention belongs to the technical field of metallurgical continuous casting, and particularly relates to a crystallizer copper plate and a use process thereof, which are characterized in that a sharkskin-imitating micro-unit array is arranged on the surface of the crystallizer copper plate, the outline length L of the sharkskin-imitating micro-unit array is 0.1-0.4 mm, the outline width H of the sharkskin-imitating micro-unit array is 0.1-0.4 mm, and the width H of the sharkskin-imitating micro-unit array is 0.1-0.4 mm. Each sharkskin-imitating micro unit is a circular or nearly circular laser etching body with a convex surface, a main ridge is arranged in the middle of the surface, two symmetrical branch ridges are arranged on two sides of the main ridge, the height V of the main ridge is 50-200 microns, and the distance between the adjacent micro units is 200-500 microns; the main ridge is arranged in the width direction of the casting blank, the included angle alpha between the branch ridges and the main ridge is 15-45 degrees, and a large angle is taken corresponding to a high-shrinkage steel grade. Compared with the prior art, the method has the beneficial effects that the sharkskin-imitating micro-unit array is prepared on the working face of the copper plate through the laser etching technology, the friction resistance between an initial setting shell and the copper plate is reduced through the fluid boundary layer effect, and the surface quality of a casting blank and the continuous casting efficiency are improved.

Description

Technical Field

[0001] This invention belongs to the field of metallurgical continuous casting technology, and particularly relates to a crystallizer copper plate and its application process. Background Technology

[0002] Continuous casting is short for continuous steel casting. In the steel production process, there are two main methods for solidifying molten steel: traditional ingot casting and continuous casting. Compared to traditional methods, continuous casting technology offers significant advantages such as greatly improving metal yield and billet quality, and saving energy. The continuous casting process involves transporting a ladle filled with refined molten steel to a turret. After the turret rotates to the pouring position, the molten steel is poured into the tundish, and then distributed to various crystallizers through the nozzle. The crystallizer is one of the core pieces of the continuous casting machine; it shapes the casting and allows it to solidify rapidly. A straightening machine and a crystallization vibration device work together to pull the casting out of the crystallizer. After cooling and electromagnetic stirring, the casting is cut into slabs of a certain length.

[0003] During continuous casting, the frictional resistance between the copper plate in the crystallizer and the initial solidified shell is the core factor leading to transverse corner cracks. Traditional techniques mainly reduce friction by optimizing the copper plate material or coating (such as chromium plating or nickel-based alloys), but the following problems still exist: high frictional resistance: smooth surfaces are prone to adhesive friction, and stress concentration at the corners leads to a crack rate of ≥5%; poor adaptability: fixed coating structures cannot match the shrinkage characteristics of different steel grades (e.g., low-carbon steel shrinkage rate 0.8%-1.2%, high-carbon steel 1.5%-2.0%); short lifespan: the coating is prone to peeling off at high temperatures, and the average service life of the copper plate is only 6-10 months. The main technical bottlenecks are: the lack of biomimetic structural design to actively regulate the fluid boundary layer; and the inability of existing groove structures to dynamically adapt to the shrinkage differences of steel grades.

[0004] Chinese invention patent CN105108082A discloses a narrow-faced copper plate for a continuous casting crystallizer, comprising a working copper plate and a back plate. A cooling mechanism is installed within the working copper plate, and the lower back of the working copper plate is connected to the back plate via an elastic support, ensuring that the steel billet in the crystallizer remains in close contact with the copper plate surface, maintaining excellent heat dissipation at all times. This design employs a wavy groove design, but the groove depth is only 20μm, which is insufficient to form effective boundary layer separation.

[0005] Chinese invention patent CN110666116B discloses a copper plate for a crystallizer and a continuous casting crystallizer. The copper plate has a mold surface for continuous metal casting and a fixed surface for back-side cooling. A section of diverting cooling ribs is arranged in the middle of the meniscus region along the cooling channel. At least one of the top and bottom ends of the diverting cooling ribs is a cone angle used to change the direction of the cooling medium's movement. This design proposes a gradient groove distribution but does not mention any inspiration for adjusting the direction in conjunction with the shrinkage characteristics of the steel grade.

[0006] Chinese invention patent CN111673057A discloses a method for processing copper plates for crystallizers, which includes fixing a chamfered copper plate to be processed to the surface of the copper plate to be processed, followed by sequential curing and hardening treatments. This solution utilizes magnetic fluid to reduce friction, but requires additional equipment and increases costs by 50%.

[0007] Conclusion: Existing technologies do not address the application of dynamic adaptation between sharkskin-like micro-units and the shrinkage characteristics of steel grades, nor do they provide a systematic solution for corner transverse cracks. Summary of the Invention

[0008] The purpose of this invention is to provide a crystallizer copper plate and its application process, which overcomes the shortcomings of the prior art. By using laser etching technology to prepare a sharkskin-like micro-unit array on the working surface of the copper plate, the frictional resistance between the initial solidification shell and the copper plate is reduced by utilizing the fluid boundary layer effect. In addition, the fishbone-shaped groove distribution is adapted to the shrinkage characteristics of different steel grades, reducing transverse cracks at the corners and improving the surface quality of the billet and the continuous casting efficiency.

[0009] To achieve the above objectives, the present invention provides the following technical solution:

[0010] One technical solution: A crystallizer copper plate, with a sharkskin-like micro-unit array on its surface. The outer length L of the sharkskin-like micro-unit is 0.1-0.4 mm, and the outer width H is 0.1-0.4 mm. The sharkskin-like micro-unit is a circular or near-circular laser-etched body with a raised surface. A main ridge is provided in the center of the surface, and two symmetrical branch ridges are provided on both sides of the main ridge. The height V of the main ridge is 50-200 μm, and the spacing between adjacent micro-units is 200-500 μm. The main ridge is arranged along the width direction of the billet, and the angle α between the branch ridges and the main ridge is 15°-45°, with a larger angle corresponding to high shrinkage steel grades.

[0011] Furthermore, when the sharkskin-like micro-unit is circular, L=H; when the sharkskin-like micro-unit is nearly circular, the difference between L and H is ≤0.05mm.

[0012] Furthermore, the laser-etched body is fabricated using a fiber laser with a wavelength of 1064nm, a power of 500-600W, and a scanning speed of 3-8m / s; after parameter optimization, the pulse frequency is 20-25kHz, the overlap rate is 30-35%, and the surface roughness Ra after etching is ≤0.8μm.

[0013] Furthermore, when the crystallizer copper plate is made of low-carbon steel, the angle between the branch ridge and the main ridge is 15°-20°, and the height of the main ridge is 75-85μm, which can suppress the concentration of shrinkage stress. When the crystallizer copper plate is made of high-carbon steel, the angle between the branch ridge and the main ridge is 40°-55°, and the height of the main ridge is 145-155μm, which enhances the boundary layer separation effect. When the crystallizer copper plate is made of stainless steel, the distribution density of the sharkskin-like micro-units increases, and the spacing between adjacent micro-units is shortened by 15%-20% from 200-500μm, thereby improving surface lubricity.

[0014] Furthermore, the sharkskin-like micro-units are arranged in a fishbone pattern or in an alternating pattern.

[0015] Furthermore, the distribution area of ​​the sharkskin-like micro-units on the copper plate of the crystallizer is not less than 80%.

[0016] Technical Solution Two: A process for using a crystallizer copper plate, wherein the vibration amplitude of the crystallizer copper plate is ±3mm, the vibration frequency is 140-150cpm, and the flow effect of the grooves around the sharkskin-like micro-unit is matched. The cooling intensity water flow rate of a single crystallizer copper plate is increased to 4-14 L / min to ensure the thermal balance of the copper plate.

[0017] Furthermore, the copper plate of the crystallizer is compatible with steel billets made of any one of low-carbon steel, high-carbon steel, alloy steel, or stainless steel.

[0018] Furthermore, the steel billet is any one of the continuously cast steel billets, including slabs, square billets, and round billets.

[0019] Furthermore, the casting speed of the continuously cast steel billet is 1.32-1.38 m / min.

[0020] Compared with the prior art, the beneficial effects of the present invention are:

[0021] 1) A sharkskin-like micro-unit array is prepared on the working surface of a copper plate by laser etching technology. The fluid boundary layer effect is used to reduce the frictional resistance between the initial solidification shell and the copper plate, thereby improving the surface quality of the billet and the continuous casting efficiency.

[0022] 2) Frictional resistance is minimized by inducing fluid boundary layer separation through micro-unit arrays, resulting in a friction coefficient reduction of ≥40%.

[0023] 3) Good dynamic adaptability; the sharkskin-like groove distribution adapts to the shrinkage characteristics of different steel grades; the groove direction changes with the width of the billet, better matching the differences in shrinkage rate of steel grades.

[0024] 4) The lifespan is extended. The laser etching process improves the surface hardness of the copper plate (HV≥250), extending the lifespan of the crystallizer copper plate to 18 months.

[0025] 5) It has a significant crack suppression effect, reducing the number of transverse corner cracks, with the rate of transverse corner cracks decreasing from 5% to below 0.5%. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of the sharkskin-inspired micro-unit structure of the present invention;

[0027] Figure 2 This is a schematic diagram of the sharkskin-like micro-unit array arrangement on the copper plate of the crystallizer in an embodiment of the present invention;

[0028] In the diagram: 1-Sharkskin-like micro-unit, 2-Crystallizer copper plate. Detailed Implementation

[0029] To further describe the present invention, specific embodiments are provided below, which will more clearly demonstrate the advantages and various effects of the present invention. Those skilled in the art should understand that these specific embodiments are illustrative of the invention and not intended to limit it.

[0030] Throughout this specification, unless otherwise specified, the terminology used herein should be understood as having the meaning commonly used in the art. Therefore, unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. In the event of any conflict, this specification shall prevail.

[0031] Unless otherwise specified, all raw materials, reagents, instruments and equipment used in this invention can be purchased from the market or prepared by existing methods.

[0032] See Figure 1-2 This invention provides a schematic diagram of a sharkskin-like micro-unit structure in an embodiment of a crystallizer copper plate. An array of sharkskin-like micro-units 1 is provided on the surface of the crystallizer copper plate 2. The outer length L of each sharkskin-like micro-unit 1 is 0.1-0.4 mm, and the outer width H is 0.1-0.4 mm. Each sharkskin-like micro-unit 1 is a laser-etched, circular or near-circular raised surface. A main ridge is centrally located on the surface, with two symmetrical branch ridges on either side. The height V of the main ridge is 50-200 μm, and the spacing between adjacent micro-units 1 is 200-500 μm. The main ridge is arranged along the width direction of the cast billet, and the angle α between the branch ridges and the main ridge is 15°-45°, with a larger angle corresponding to high-shrinkage steel grades. When the sharkskin-like micro-unit is circular, L=H; when the sharkskin-like micro-unit is near-circular, the difference between L and H is ≤0.05 mm.

[0033] The laser-etched body is fabricated using a fiber laser with a wavelength of 1064nm, a power of 500-600W, and a scanning speed of 3-8m / s. After parameter optimization, the pulse frequency is 20-25kHz, the overlap rate is 30-35%, and the surface roughness Ra after etching is ≤0.8μm.

[0034] When the crystallizer copper plate 2 is made of low-carbon steel, the angle between the branch ridge and the main ridge is 15°-20°, and the height of the main ridge is 75-85μm, which can suppress the concentration of shrinkage stress. When the crystallizer copper plate 2 is made of high-carbon steel, the angle between the branch ridge and the main ridge is 40°-55°, and the height of the main ridge is 145-155μm, which enhances the boundary layer separation effect. When the crystallizer copper plate 2 is made of stainless steel, the distribution density of the sharkskin-like micro-units increases, and the spacing between adjacent micro-units is shortened by 15%-20% from 200-500μm, which improves surface lubricity.

[0035] The sharkskin-like micro-units 1 are arranged in a fishbone pattern or in a staggered arrangement. The grooves around the micro-units form a uniform cooling water flow channel, increasing the cooling intensity and water flow rate of a single crystallizer copper plate to 4-14 L / min, ensuring thermal balance of the copper plate. To guarantee the cooling effect, the distribution area of ​​the sharkskin-like micro-units 1 on the crystallizer copper plate 2 is not less than 80%. The following is a description of the application process of the crystallizer copper plate of this invention in various situations.

[0036] Example 1

[0037] Take the continuous casting of low-carbon steel slabs as an example.

[0038] Process parameters:

[0039] Steel grade: Q235B;

[0040] Billet dimensions: 220mm × 1500mm;

[0041] Groove design: main ridge height 80μm, included angle 15°, spacing between adjacent micro-units 1 300μm;

[0042] Vibration parameters: amplitude ±2.5mm, frequency 120cpm.

[0043] Implementation results:

[0044] Coefficient of friction: decreased from 0.21 to 0.10;

[0045] Crack rate: Corner transverse cracks decreased from 4.8% to 0.2%;

[0046] Copper plate lifespan: After 18 months of use, the grooves are clear and show no wear.

[0047] Example 2

[0048] Take the continuous casting of high-carbon steel square billets as an example.

[0049] Process parameters:

[0050] Steel grade: 60# high carbon steel;

[0051] Billet dimensions: 150mm × 150mm;

[0052] Groove design: main ridge height 150μm, included angle 45°, sharkskin-like micro-unit distribution density increased by 30%;

[0053] Cooling water flow rate: 25 m³ / h (15% more than the traditional method).

[0054] Implementation results:

[0055] Surface quality: No visible cracks at the corners of the cast billet; oxide scale thickness reduced by 40%;

[0056] Pulling speed increased from 1.0 m / min to 1.1 m / min;

[0057] Energy consumption: The power consumption of the vibration system is reduced by 18%.

[0058] Copper plate lifespan: After 16 months of use, the grooves are clear and show no wear.

[0059] Example 3

[0060] Take the continuous casting of stainless steel round billets as an example.

[0061] Process parameters:

[0062] Steel type: 304L stainless steel;

[0063] Billet specifications: Φ250mm round billet;

[0064] Groove design: Main ridge height 120μm, main groove direction dynamically adjusted (±5° with shrinkage rate);

[0065] Laser parameters: power 600W, scanning speed 5m / s.

[0066] Implementation results:

[0067] Crack control: The corner transverse crack rate decreased from 3.5% to 0.1%;

[0068] Surface roughness: Ra decreased from 1.2 μm to 0.6 μm;

[0069] Copper plate lifespan: The copper plate replacement interval has been extended to 20 months.

[0070] Example 4

[0071] Take the continuous casting of alloy steel shaped billets as an example.

[0072] Process parameters:

[0073] Steel grade: 42CrMo;

[0074] Billet shape: H-shaped cross section (web thickness 80mm);

[0075] Trench design: main ridge height and depth 200μm, branch ridge depth 100μm, included angle 30°;

[0076] Vibration mode: Asymmetric vibration (web amplitude ±3mm, flange amplitude ±2mm).

[0077] Implementation results:

[0078] Crack suppression: H-shaped corner cracks are completely eliminated;

[0079] Copper plate lifespan: The copper plate replacement interval has been extended to 21 months.

[0080] Example 5

[0081] Take high-speed continuous casting of thin slabs as an example.

[0082] Process parameters:

[0083] Steel grade: SPHC hot-rolled low-carbon steel;

[0084] Billet thickness: 70mm;

[0085] Pulling speed: 2.5 m / min;

[0086] Trench optimization: Nanoscale trench edge polishing (Ra≤0.2μm) reduces initial shell adhesion.

[0087] Implementation results:

[0088] Coefficient of friction: stable at 0.08-0.09;

[0089] Surface defects: No star-shaped cracks or longitudinal cracks;

[0090] Cost-effectiveness: The cost of copper plate loss per ton of steel is reduced by 45%.

[0091] Copper plate lifespan: Copper plate replacement interval extended to 19 months.

[0092] Those skilled in the art should recognize that the above embodiments are merely illustrative of the invention and not intended to limit it, but are similarly limited to the scope of the invention. Variations and modifications to the above embodiments will fall within the protection scope of the claims. It should be understood that the endpoints and values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of various ranges, the endpoint values ​​of various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0093] It should be noted that in this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Additionally, the term "and / or" as used herein is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A alone, A and B simultaneously, or B alone.

[0094] The above description is merely a specific embodiment of the present invention, enabling those skilled in the art to understand or implement the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the present invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features claimed herein.

Claims

1. A crystallizer copper plate characterized by, The surface of the crystallizer copper plate is provided with a sharkskin microcell array, the outer contour length L of the sharkskin microcell is 0.1-0.4mm, the outer contour width H is 0.1-0.4mm, the sharkskin microcell is a laser etching body with a surface protrusion of a circular or nearly circular shape, a main ridge is arranged in the middle of the surface, two symmetrical branch ridges are arranged on both sides of the main ridge, the height V of the main ridge is 50-200μm, and the spacing between adjacent microcells is 200-500μm; the main ridge is arranged along the width direction of the cast blank, the included angle α between the branch ridge and the main ridge is 15°-45°, and a large angle is taken for corresponding high-shrinkage steel grades.

2. A crystallizer copper plate according to claim 1, characterized in that When the sharkskin microcell is circular, L=H; when the sharkskin microcell is nearly circular, the difference between L and H is ≤0.05mm.

3. The crystallizer copper plate of claim 1, wherein, The laser etching body is made of a fiber laser with a wavelength of 1064nm, a power of 500-600W, and a scanning speed of 3-8m / s; after parameter optimization, the pulse frequency is 20-25kHz, the overlap rate is 30-35%, and the surface roughness Ra after etching is ≤0.8μm.

4. The crystallizer copper plate of claim 1, wherein, When the crystallizer copper plate is suitable for low-carbon steel, the included angle between the branch ridge and the main ridge is 15°-20°, and the height of the main ridge is 75-85μm, so as to inhibit shrinkage stress concentration; when the crystallizer copper plate is suitable for high-carbon steel, the included angle between the branch ridge and the main ridge is 40°-55°, and the height of the main ridge is 145-155μm, so as to enhance the boundary layer separation effect; when the crystallizer copper plate is suitable for stainless steel, the distribution density of the sharkskin microcell is increased, and the spacing between adjacent microcells is shortened by 15%-20% based on 200-500μm, so as to improve the surface lubricity.

5. The crystallizer copper plate of claim 1, wherein, The sharkskin microcell is arranged in a fishbone shape or staggered front and back.

6. A crystallizer copper plate according to claim 1, characterized in that The distribution area of the sharkskin microcell on the crystallizer copper plate is not less than 80%.

7. The process for using a crystallizer copper plate according to any one of claims 1 to 6, characterized in that, The vibration amplitude of the crystallizer copper plate is ±3mm, and the vibration frequency is 140-150cpm, so as to match the flow effect of the surrounding groove of the sharkskin microcell, the cooling intensity of a single crystallizer copper plate is increased to 4-14 L / min, and the thermal balance of the copper plate is ensured.

8. The process for using a crystallizer copper plate according to claim 7, characterized in that, The steel billet material adapted by the crystallizer copper plate is any one of low-carbon steel, high-carbon steel, alloy steel and stainless steel.

9. The process for using a crystallizer copper plate according to claim 7, wherein, The steel billet is any one of a slab, a bloom and a round billet.

10. The process for using a crystallizer copper plate according to claim 7, wherein, The casting speed of the continuous casting steel billet is 1.32-1.38m / min.

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