A method for laser cladding gradient layers on the surface of a copper continuous casting crystallizer

Abstract

A method for laser cladding a gradient layer on the surface of a copper continuous casting crystallizer relates to a surface repair method for continuous casting crystallizers. The laser cladding gradient layer of this invention consists of an iron-based cladding layer and a nickel-based cladding layer. The iron-based cladding layer, serving as a transition layer, is composed of pure iron and pure cobalt metal powders. The nickel-based cladding layer, serving as the working layer, is composed of pure nickel, pure chromium, pure cobalt, and 99.999% yttrium oxide powder. These metal powders are dried at 200°C for 2 hours, then dry-milled at low speed using Al2O3 microspheres as the grinding media. A laser is used to transfer the intersection zone of the mixed powder and the laser light onto the workpiece to prepare the laser cladding gradient layer. This invention's laser cladding gradient layer strengthens the surface of the copper continuous casting crystallizer, enabling repeated repair of the copper crystallizer and improving material utilization.

Description

Technical Field

[0001] This invention relates to a method for repairing the surface of a continuous casting crystallizer, and more particularly to a method for laser cladding a gradient layer onto the surface of a copper continuous casting crystallizer. Background Technology

[0002] The crystallizer, a core component of continuous casting equipment, assists in the solidification and shaping of molten metal. Copper, due to its excellent thermal conductivity, is used as the raw material for crystallizers. However, copper is soft and has poor wear resistance, making it prone to severe wear during crystallizer use. To improve the performance and service life of copper crystallizers, surface treatment technology is applied.

[0003] Currently, electroplating and thermal spraying are commonly used to strengthen the surface of copper crystallizers. However, the coatings prepared by these two processes have low bonding strength with the copper crystallizer and are prone to peeling off, resulting in coating failure.

[0004] The emergence of laser cladding technology promises to change this situation. This is because the cladding layer prepared by laser cladding has a metallurgical bond with the substrate, a low dilution rate, and a uniform and dense internal structure, which can effectively improve the surface properties of copper crystallizers. At the same time, the use of laser cladding technology can not only significantly increase the service life of copper crystallizers, but also enable repeated repairs of copper crystallizers, improving material utilization.

[0005] In the continuous casting process, the existing copper continuous casting crystallizer continuously cools the high-temperature molten metal. The copper crystallizer is in direct contact with both the high-temperature molten metal and the cooling water. There is a large temperature gradient inside the crystallizer, while the surface is subjected to high-temperature oxidation and thermal fatigue. Summary of the Invention

[0006] The purpose of this invention is to provide a method for laser cladding a gradient layer onto the surface of a copper continuous casting crystallizer. This invention utilizes a high-energy laser beam as a heat source to simultaneously melt the cladding material added to the substrate surface and the substrate surface layer. After rapid cooling, a cladding layer with low dilution and metallurgical bonding to the substrate is formed. By adjusting the composition and structure of the laser cladding layer, the wear resistance of the continuous casting copper crystallizer surface is improved, increasing its effective service life.

[0007] The objective of this invention is achieved through the following technical solution:

[0008] A method for laser cladding a gradient layer on the surface of a copper continuous casting crystallizer, wherein the laser cladding gradient layer is composed of an iron-based cladding layer and a nickel-based cladding layer, wherein the iron-based cladding layer, as a transition layer, is composed of pure iron metal powder and pure cobalt metal powder; and the nickel-based cladding layer, as a working layer, is composed of a combination of pure nickel metal powder, pure chromium metal powder and pure cobalt powder.

[0009] The cladding process is as follows:

[0010] (1) Use a grinding wheel to remove the oxide layer on the surface of the copper crystallizer, then use gauze to polish the surface of the copper crystallizer, and after polishing, use alcohol to clean the surface of the copper crystallizer.

[0011] (2) After the metal powder is dried at 200° for 2 to 5 hours, it is ball-milled for 2 to 6 hours at a speed of 30 to 60 r / min to obtain uniform powder. The laser is then used to transfer the intersection area of ​​the mixed powder and the laser to the laser cladding gradient layer above the workpiece.

[0012] (3) Surface repair is performed by adjusting the process parameters of laser cladding; the laser power is 5000~6000 kW, and the laser power density is 50~500 W / mm². 2 The scanning speed is 20~200 mm / min, and the spot area is 50~110 mm. 2 ;

[0013] (4) The surface of the copper continuous casting crystallizer is machined and polished by an automatic mechanical grinding and polishing machine until the surface of the copper continuous casting crystallizer meets the accuracy requirements for use and a surface cladding layer with excellent performance is obtained.

[0014] (5) The coating thickness obtained on the surface of the copper crystallizer after laser cladding treatment is 200~2000 μm.

[0015] The method for laser cladding a gradient layer on the surface of a copper continuous casting crystallizer, wherein the cladding transition layer is composed of an iron-based cladding layer with a weight percentage of Co 2~15% and the balance being Fe; the particle size of the pure iron metal powder is 100~300 μm.

[0016] The method for laser cladding a gradient layer on the surface of a copper continuous casting crystallizer, wherein the pure cobalt metal powder has a particle size of 80~280 μm.

[0017] The method for laser cladding a gradient layer on the surface of a copper continuous casting crystallizer, wherein the laser cladding working layer is composed of nickel-based powder, the composition of which by weight percentage is Cr 15~35%, Co 5~25%, Y2O3 0.5~2%, and the balance is Ni.

[0018] The method for laser cladding a gradient layer on the surface of a copper continuous casting crystallizer, wherein the pure nickel metal powder has a particle size of 50~250 μm.

[0019] The method for laser cladding a gradient layer on the surface of a copper continuous casting crystallizer, wherein the pure chromium metal powder has a particle size of 90~220 μm.

[0020] The method for laser cladding a gradient layer on the surface of a copper continuous casting crystallizer, wherein the yttrium oxide powder has a particle size of 3.5-10 μm.

[0021] The method for laser cladding a gradient layer on the surface of a copper continuous casting crystallizer, wherein the pure cobalt metal powder has a particle size of 80~280 μm.

[0022] The advantages and effects of this invention are:

[0023] This invention features a flexible process, simple operation, and a wide range of cladding materials, facilitating industrial production. The laser cladding gradient layer strengthens the surface of the copper continuous casting crystallizer, enabling the remanufacturing and repair of the copper crystallizer substrate and improving material utilization. Attached Figure Description

[0024] Figure 1 The image shows the cross-sectional microstructure of the sample after laser cladding gradient layer treatment in Example 1.

[0025] Figure 2 This is a micrograph of the sample surface after laser cladding gradient layer treatment in Example 1.

[0026] Figure 3 This is a photograph of the actual workpiece surface after laser cladding in Example 1, showing the overlapping area formed on the surface of the workpiece.

[0027] Figure 4 This is a photograph of the actual workpiece after laser cladding on the surface of Example 1. Detailed Implementation Example 1

[0028] In this example, the laser cladding gradient layer consists of an iron-based cladding layer and a nickel-based cladding layer. The iron-based cladding layer, serving as a transition layer, is composed of pure iron metal powder and pure cobalt metal powder. The particle size of the pure iron metal powder is 110 μm, and the particle size of the pure cobalt metal powder is 120 μm. The alloy powder contains 5% Co by weight, with the balance being Fe. The nickel-based cladding layer, serving as the working layer, is composed of pure nickel metal powder, pure chromium metal powder, and pure cobalt powder. The particle size of the pure nickel metal powder is 150 μm, the particle size of the pure chromium metal powder is 140 μm, the particle size of the pure cobalt metal powder is 160 μm, and the particle size of the yttrium oxide powder is 3.5-7 μm. The alloy powder composition contains 18% Cr, 15% Co, 0.7% Y2O3 by weight, with the balance being Ni.

[0029] Use a grinding wheel to remove the oxide layer on the surface of the copper crystallizer, then use gauze to polish the surface of the copper crystallizer, and finally use alcohol to clean the surface of the copper crystallizer.

[0030] After drying the metal powder at 200°C for 2 hours, it was ball-milled for 2 hours at a ball mill speed of 22 r / min to obtain uniform powder. The laser was then used to transfer the intersection zone of the mixed powder and the laser to the workpiece to prepare a laser cladding gradient layer.

[0031] Laser cladding technology was employed, with process parameters controlled for surface repair. The laser power used to prepare the iron-based cladding layer was 5250 kW, and the laser power density was 50 W / mm². 2 The scanning speed is 20 mm / min, and the spot area is 50 mm. 2 The laser power used to prepare the nickel-based cladding layer was 5760 kW, and the laser power density was 360 W / mm². 2 The scanning speed is 150 mm / min, and the spot area is 100 mm. 2 The actual surface of the laser cladding overlap zone formed on the substrate of the copper continuous casting crystallizer (see...). Figure 3 ).

[0032] The surface of the copper continuous casting crystallizer is post-treated by mechanical processing and polishing with an automatic grinding and polishing machine until the surface of the copper continuous casting crystallizer substrate meets the required precision for use, thus obtaining a surface cladding layer with relatively general performance (see...). Figure 4 The microstructure of the sample after processing is shown in the figure. Figure 1 and Figure 2 .

[0033] The coating thickness obtained on the surface of the copper continuous casting crystallizer after laser cladding treatment is 800 μm. Its Vickers hardness and wear test results are shown in Table 1.

[0034] Table 1. Microhardness and wear test results of the surface of the copper continuous casting crystallizer after laser cladding treatment.

[0035] Sample number test items 1 2 3 4 5 average value Hardness (HV) 522 528 536 534 523 528.6 Wear amount (g) 0.033 0.027 0.021 0.022 0.032 0.0270

[0036] The above embodiments are only used for explanation and illustration of the present invention and are not intended to limit the present invention. Example 2

[0037] In this example, the laser cladding gradient layer consists of an iron-based cladding layer and a nickel-based cladding layer. The iron-based cladding layer, serving as a transition layer, is composed of pure iron metal powder and pure cobalt metal powder. The pure iron metal powder has a particle size of 100 μm, and the pure cobalt metal powder has a particle size of 80 μm. The alloy powder has a weight percentage of 8% Co and the balance being Fe. The nickel-based cladding layer, serving as the working layer, is composed of pure nickel metal powder, pure chromium metal powder, and pure cobalt powder. The pure nickel metal powder has a particle size of 100 μm, the pure chromium metal powder has a particle size of 90 μm, the pure cobalt metal powder has a particle size of 80 μm, and the yttrium oxide powder has a particle size of 3.5-7 μm. The alloy powder composition has a weight percentage of 16% Cr, 8% Co, 0.9% Y2O3, and the balance being Ni.

[0038] Use a grinding wheel to remove the oxide layer on the surface of the copper crystallizer, then use gauze to polish the surface of the copper crystallizer, and finally use alcohol to clean the surface of the copper crystallizer.

[0039] After drying the metal powder at 200°C for 5 hours, it was ball-milled for 1 hour at a ball mill speed of 25 r / min to obtain uniform powder. The laser was then used to transfer the intersection zone of the mixed powder and the laser to the workpiece to prepare a laser cladding gradient layer.

[0040] Laser cladding technology was employed, with process parameters controlled for surface repair. The laser power used to prepare the iron-based cladding layer was 5900 kW, and the laser power density was 378 W / mm². 2 The scanning speed was 86 mm / min, and the spot area was 81 mm. 2 The laser power used to prepare the nickel-based cladding layer was 5800 kW, and the laser power density was 220 W / mm². 2 The scanning speed is 50 mm / min, and the spot area is 70 mm. 2 .

[0041] The surface of the copper continuous casting crystallizer is machined and polished using an automatic mechanical grinding and polishing machine until it meets the required precision and a relatively high-performance surface cladding layer is obtained.

[0042] The coating thickness obtained on the surface of the copper continuous casting crystallizer after laser cladding treatment is 1000 μm. Its Vickers hardness and wear test results are shown in Table 2.

[0043] Table 2 Microhardness and wear test results of the surface of the copper continuous casting crystallizer after laser cladding treatment.

[0044] Sample number test items 1 2 3 4 5 average value Hardness (HV) 535 524 532 536 531 531.6 Wear amount (g) 0.022 0.026 0.024 0.021 0.025 0.0236

[0045] The above embodiments are only used for explanation and illustration of the present invention and are not intended to limit the present invention. Example 3

[0046] In this example, the laser cladding gradient layer consists of an iron-based cladding layer and a nickel-based cladding layer. The iron-based cladding layer, serving as a transition layer, is composed of pure iron metal powder and pure cobalt metal powder. The particle size of the pure iron metal powder is 300 μm, and the particle size of the pure cobalt metal powder is 280 μm. The alloy powder contains 12% Co by weight, with the balance being Fe. The nickel-based cladding layer, serving as the working layer, is composed of pure nickel metal powder, pure chromium metal powder, and pure cobalt powder. The particle size of the pure nickel metal powder is 50 μm, the particle size of the pure chromium metal powder is 90 μm, the particle size of the pure cobalt metal powder is 80 μm, and the particle size of the yttrium oxide powder is 3.5-7 μm. The alloy powder composition contains 20% Cr, 10% Co, 1.1% Y2O3 by weight, with the balance being Ni.

[0047] Use a grinding wheel to remove the oxide layer on the surface of the copper crystallizer, then use gauze to polish the surface of the copper crystallizer, and finally use alcohol to clean the surface of the copper crystallizer.

[0048] After drying the metal powder at 200°C for 3 hours, it was ball-milled for 6 hours at a ball mill speed of 32 r / min to obtain uniform powder. The laser was then used to transfer the intersection zone of the mixed powder and the laser to the workpiece to prepare a laser cladding gradient layer.

[0049] Surface repair was achieved using laser cladding technology with controlled process parameters. The laser power used to prepare the iron-based cladding layer was 5500 kW, and the laser power density was 500 W / mm². 2 The scanning speed is 180 mm / min, and the spot area is 85 mm. 2 The laser power used to prepare the nickel-based cladding layer was 6000 kW, and the laser power density was 420 W / mm². 2 The scanning speed is 200 mm / min, and the spot area is 100 mm. 2 .

[0050] The surface of the copper continuous casting crystallizer is machined and polished using an automatic mechanical grinding and polishing machine until it meets the required precision and a surface cladding layer with relatively good performance is obtained.

[0051] The coating thickness obtained on the surface of the copper continuous casting crystallizer after laser cladding treatment is 1500 μm. Its Vickers hardness and wear test results are shown in Table 3.

[0052] Table 3 Microhardness and wear test results of the surface of the copper continuous casting crystallizer after laser cladding treatment.

[0053] Sample number test items 1 2 3 4 5 average value Hardness (HV) 546 542 535 541 521 537.0 Wear amount (g) 0.015 0.017 0.022 0.019 0.031 0.0214

[0054] The above embodiments are only used for explanation and illustration of the present invention and are not intended to limit the present invention. Example 4

[0055] In this example, the laser cladding gradient layer consists of an iron-based cladding layer and a nickel-based cladding layer. The iron-based cladding layer, serving as a transition layer, is composed of pure iron metal powder and pure cobalt metal powder. The particle size of the pure iron metal powder is 220 μm, and the particle size of the pure cobalt metal powder is 240 μm. The alloy powder has a weight percentage of 7% Co and the balance is Fe. The nickel-based cladding layer, serving as the working layer, is composed of pure nickel metal powder, pure chromium metal powder, and pure cobalt powder. The particle size of the pure nickel metal powder is 250 μm, the particle size of the pure chromium metal powder is 220 μm, the particle size of the pure cobalt metal powder is 280 μm, and the particle size of the yttrium oxide powder is 3.5-7 μm. The alloy powder composition has a weight percentage of 30% Cr, 25% Co, 1.3% Y2O3, and the balance is Ni.

[0056] Use a grinding wheel to remove the oxide layer on the surface of the copper crystallizer, then use gauze to polish the surface of the copper crystallizer, and finally use alcohol to clean the surface of the copper crystallizer.

[0057] After drying the metal powder at 200°C for 3.6 hours, it was ball-milled for 4 hours at a ball mill speed of 30 r / min to obtain uniform powder. The laser was then used to transfer the intersection zone of the mixed powder and the laser to the workpiece to prepare a laser cladding gradient layer.

[0058] Laser cladding technology was employed, with process parameters controlled for surface repair. The laser power used to prepare the iron-based cladding layer was 5000 kW, and the laser power density was 223 W / mm². 2 The scanning speed was 67 mm / min, and the spot area was 74 mm. 2 The laser power used to prepare the nickel-based cladding layer was 5390 kW, and the laser power density was 345 W / mm². 2 The scanning speed was 112 mm / min, and the spot area was 91 mm. 2 .

[0059] The surface of the copper continuous casting crystallizer is machined and polished using an automatic mechanical grinding and polishing machine until it meets the required precision and a relatively high-performance surface cladding layer is obtained.

[0060] The coating thickness obtained on the surface of the copper continuous casting crystallizer after laser cladding treatment is 1350 μm. Its Vickers hardness and wear test results are shown in Table 4.

[0061] Table 4 Microhardness and wear test results of the surface of the copper continuous casting crystallizer after laser cladding treatment.

[0062] Sample number test items 1 2 3 4 5 average value Hardness (HV) 553 542 519 537 528 535.8 Wear amount (g) 0.013 0.017 0.033 0.021 0.029 0.0226

[0063] The above embodiments are only used for explanation and illustration of the present invention and are not intended to limit the present invention. Example 5

[0064] In this example, the laser cladding gradient layer consists of an iron-based cladding layer and a nickel-based cladding layer. The iron-based cladding layer, serving as a transition layer, is composed of pure iron metal powder and pure cobalt metal powder. The particle size of the pure iron metal powder is 170 μm, and the particle size of the pure cobalt metal powder is 190 μm. The alloy powder contains 15% Co by weight, with the balance being Fe. The nickel-based cladding layer, serving as the working layer, is composed of pure nickel metal powder, pure chromium metal powder, and pure cobalt powder. The particle size of the pure nickel metal powder is 130 μm, the particle size of the pure chromium metal powder is 155 μm, the particle size of the pure cobalt metal powder is 180 μm, and the particle size of the yttrium oxide powder is 3.5-7 μm. The alloy powder composition contains 25% Cr, 5% Co, 1.5% Y2O3 by weight, with the balance being Ni.

[0065] Use a grinding wheel to remove the oxide layer on the surface of the copper crystallizer, then use gauze to polish the surface of the copper crystallizer, and finally use alcohol to clean the surface of the copper crystallizer.

[0066] After drying the metal powder at 200°C for 5 hours, it was ball-milled for 2.8 hours at a ball mill speed of 33 r / min to obtain uniform powder. The laser was then used to transfer the intersection zone of the mixed powder and the laser to the workpiece to prepare a laser cladding gradient layer.

[0067] Laser cladding technology was employed, with process parameters controlled for surface repair. The laser power used to prepare the iron-based cladding layer was 5690 kW, and the laser power density was 198 W / mm². 2 The scanning speed was 113 mm / min, and the spot area was 95 mm. 2 The laser power used to prepare the nickel-based cladding layer was 5930 kW, and the laser power density was 409 W / mm². 2 The scanning speed was 108 mm / min, and the spot area was 68 mm. 2 .

[0068] The surface of the copper continuous casting crystallizer is machined and polished using an automatic mechanical grinding and polishing machine until it meets the required precision for use, resulting in a surface cladding layer with relatively low performance.

[0069] The coating thickness obtained on the surface of the copper continuous casting crystallizer after laser cladding treatment is 890 μm. Its Vickers hardness and wear test results are shown in Table 5.

[0070] Table 5 Microhardness and wear test results of the surface of the copper continuous casting crystallizer after laser cladding treatment.

[0071] Sample number test items 1 2 3 4 5 average value Hardness (HV) 525 531 528 534 518 525 Wear amount (g) 0.030 0.025 0.029 0.021 0.034 0.0278

[0072] The above embodiments are only used for explanation and illustration of the present invention and are not intended to limit the present invention. Example 6

[0073] In this example, the laser cladding gradient layer consists of an iron-based cladding layer and a nickel-based cladding layer. The iron-based cladding layer, serving as a transition layer, is composed of pure iron metal powder and pure cobalt metal powder. The particle size of both the pure iron and pure cobalt metal powders is 210 μm. The alloy powders contain 11% Co by weight, with the balance being Fe. The nickel-based cladding layer, serving as the working layer, is composed of pure nickel metal powder, pure chromium metal powder, and pure cobalt powder. The particle size of the pure nickel metal powder is 80 μm, the pure chromium metal powder is 170 μm, the pure cobalt metal powder is 230 μm, and the yttrium oxide powder has a particle size of 3.5-7 μm. The alloy powders contain 35% Cr, 7% Co, 1.7% Y₂O₃ by weight, with the balance being Ni.

[0074] Use a grinding wheel to remove the oxide layer on the surface of the copper crystallizer, then use gauze to polish the surface of the copper crystallizer, and finally use alcohol to clean the surface of the copper crystallizer.

[0075] After drying the metal powder at 200°C for 4 hours, it was ball-milled for 6 hours at a ball mill speed of 40 r / min to obtain uniform powder. The laser was then used to transfer the intersection zone of the mixed powder and the laser to the workpiece to prepare a laser cladding gradient layer.

[0076] Laser cladding technology was employed, with process parameters controlled for surface repair. The laser power used to prepare the iron-based cladding layer was 5260 kW, and the laser power density was 419 W / mm². 2 The scanning speed was 156 mm / min, and the spot area was 101 mm. 2 The laser power used to prepare the nickel-based cladding layer was 5780 kW, and the laser power density was 399 W / mm². 2 The scanning speed was 169 mm / min, and the spot area was 58 mm. 2 .

[0077] The surface of the copper continuous casting crystallizer is machined and polished using an automatic mechanical grinding and polishing machine until it meets the required precision for use, thus obtaining a surface cladding layer with relatively average performance.

[0078] The coating thickness obtained on the surface of the copper continuous casting crystallizer after laser cladding treatment is 2000 μm. Its Vickers hardness and wear test results are shown in Table 6.

[0079] Table 6 Microhardness and wear test results of the surface of the copper continuous casting crystallizer after laser cladding treatment.

[0080] Sample number test items 1 2 3 4 5 average value Hardness (HV) 553 536 518 516 522 529 Wear amount (g) 0.013 0.021 0.034 0.035 0.030 0.0266

[0081] The above embodiments are only used for explanation and illustration of the present invention and are not intended to limit the present invention.

Claims

1. A method for laser cladding a gradient layer onto the surface of a copper continuous casting crystallizer, characterized in that, The laser cladding gradient layer consists of an iron-based cladding layer and a nickel-based cladding layer. The iron-based cladding layer, as a transition layer, is composed of pure iron metal powder and pure cobalt metal powder. The nickel-based cladding layer, as a working layer, is composed of a combination of pure nickel metal powder, pure chromium metal powder, and pure cobalt powder. The cladding process is as follows: (1) Use a grinding wheel to remove the oxide layer on the surface of the copper crystallizer, then use gauze to polish the surface of the copper crystallizer, and after polishing, use alcohol to clean the surface of the copper crystallizer. (2) After the metal powder is dried at 200° for 2 to 5 hours, it is ball-milled for 2 to 6 hours at a speed of 30 to 60 r / min to obtain uniform powder. The laser is then used to transfer the intersection area of ​​the mixed powder and the laser to the laser cladding gradient layer above the workpiece. (3) Surface repair is performed by adjusting the process parameters of laser cladding; the laser power is 5000~6000 kW, and the laser power density is 50~500 W / mm². 2 The scanning speed is 20~200 mm / min, and the spot area is 50~110 mm. 2 ; (4) The surface of the copper continuous casting crystallizer is machined and polished by an automatic mechanical grinding and polishing machine until the surface of the copper continuous casting crystallizer meets the accuracy requirements for use and a high-performance surface cladding layer is obtained. (5) The coating thickness obtained on the surface of the copper crystallizer after laser cladding is 200~2000 μm; The transition layer is composed of an iron-based cladding layer, with a weight percentage of Co 2~15% and the balance being Fe; the particle size of the pure iron metal powder is 100~300 μm; The particle size of pure cobalt metal powder is 80~280 μm; The laser cladding working layer is composed of nickel-based powder, the composition of which by weight percentage is Cr 15~35%, Co 5~25%, Y2O3 0.5~2%, and the balance is Ni; The particle size of the pure nickel metal powder is 50~250 μm; The particle size of the pure chromium metal powder is 90~220 μm; The particle size of the Y2O3 powder is 3.5-10 μm; The particle size of the pure cobalt metal powder is 80~280 μm.

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