Cobalt-based alloy powder and application thereof

Abstract

The invention discloses cobalt-based alloy powder and application thereof, and belongs to the technical field of metal alloy materials. The cobalt-based alloy powder comprises the following components in percentage by mass: 0.2 to 0.6 percent of C, 2.0 to 3.0 percent of Si, 2.0 to 3.0 percent of Fe, 25.0 to 32.0 percent of Cr, 5.0 to 7.0 percent of Mo, 1.0 to 3.0 percent of Mn, 0.1 to 9.0 percent of W, 2.0 to 12.0 percent of Ni and the balance of Co and inevitable impurities. The cobalt-based alloy powder provided by the invention can be used for repairing a nut column through laser cladding, a cladding layer without cracks, air holes, inclusions and other defects on the surface and the interior can be obtained after cladding under certain laser power, the average Vickers hardness of the cladding layer can reach 434.3 Hv, meanwhile, the cobalt-based alloy powder has excellent wear resistance, and the service life of the cladding layer is prolonged. The method has remarkable advantages in the aspect of improving the material surface performance, and is suitable for various repair scenes needing high hardness and wear resistance.

Description

Technical Field

[0001] The present invention relates to the technical field of metal alloy materials, and particularly relates to a cobalt-based alloy powder and its application. Background Art

[0002] The vertical ship lift is one of the permanent navigation facilities of the Three Gorges Water Control Project. Its main function is to provide a rapid dam-crossing channel for passenger and cargo ships and special ships. The key structure to ensure the safe operation of the vertical ship lift is the nut column. However, during the long-term use of the nut column (when docking with the locking block, there is a large extrusion, or due to hard objects on the surface, the structure of the nut column is damaged after docking), defects such as corrosion, local rolling depressions, and wear will appear on the surface, affecting its service life. Therefore, it is necessary to explore a suitable surface repair and modification process to repair the nut column. During the repair process of the nut column, the thermal influence should be controlled to the minimum as much as possible. The repair layer should have no obvious defects and cannot peel off. After the repair is completed, the surface hardness of the repaired position should not be lower than 230 HB, and it should have good anti-wear performance.

[0003] As an energy-saving, environmentally friendly, and efficient surface modification technology, laser cladding has improved the defects existing in modification technologies such as electroplating, chemical vapor deposition, and thermal spraying, such as environmental pollution, poor bonding between the substrate and the cladding layer, and easy occurrence of pores, cracks and other problems. In addition, a suitable laser cladding process can not only ensure that the thermal influence on the substrate is as small as possible, but also obtain a cladding layer with excellent comprehensive properties such as high hardness, high strength, and high wear resistance.

[0004] Combined with the requirements of the surface repair process of the nut column of the vertical ship lift, there is currently no suitable alloy material that can be used to repair the nut column. Therefore, how to design an alloy material and process for repairing the surface defects of large nut columns to provide technical guidance for ensuring their service life and equipment safety is a technical problem that those skilled in the art need to solve currently. Summary of the Invention

[0005] Aiming at the deficiencies existing in the prior art, the purpose of the present invention is to provide a cobalt-based alloy powder and its application to solve the problem of the lack of suitable nut column repair materials in the prior art.

[0006] The technical solution of the present invention to solve the above technical problems is as follows: Provide a cobalt-based alloy powder, which includes the following components in mass percentage according to the elemental composition: 0.2 - 0.6% C, 2.0 - 3.0% Si, 2.0 - 3.0% Fe, 25.0 - 32.0% Cr, 5.0 - 7.0% Mo, 1.0 - 3.0% Mn, 0.1 - 9.0% W, 2.0 - 12.0% Ni, and the balance is Co and unavoidable impurities.

[0007] The beneficial effects of the present invention are: C: The main role of element C is to combine with strong carbide-forming elements during the cladding process to form carbide particles, thereby improving the hardness and wear resistance of the cladding layer.

[0008] Si: Element Si can improve the comprehensive performance of the cladding layer by reducing the melting point of the alloy and forming eutectics with low melting points with other alloying elements.

[0009] Fe: Element Fe can play a role in solid solution strengthening and promote the stability of the austenite structure. In addition, element Fe can also improve the wettability between the substrate and the cladding layer, reducing defects such as pores or cracks in the cladding layer.

[0010] Mn: As an austenite stabilizing element, Mn can improve the stability of austenite at room temperature. And the addition of an appropriate amount of element Mn can improve the hardness and strength of the alloy.

[0011] Cr, W, Mo: They mainly play a role in solid solution strengthening and passivation, which can effectively improve the surface stability of the alloy, and then greatly improve its corrosion resistance, high-temperature oxidation resistance, and thermal fatigue performance, etc.

[0012] Ni: Element Ni can play a synergistic role in solid solution strengthening with other elements and can also effectively improve the high-temperature mechanical properties of the alloy.

[0013] Furthermore, according to the elemental composition, the cobalt-based alloy powder includes the following components in mass percentages: 0.25% C, 2.0% Si, 2.0% Fe, 27.5% Cr, 5.5% Mo, 1.0% Mn, 0.15% W, 2.5% Ni, and the balance is Co and inevitable impurities.

[0014] Furthermore, the particle size of the cobalt-based alloy powder is 100 - 325 μm.

[0015] Furthermore, the present invention also provides an application of the above cobalt-based alloy powder in the repair of nut studs.

[0016] Furthermore, the method for repairing nut studs with the cobalt-based alloy powder is laser cladding, and the specific steps of laser cladding are as follows: S1. Pretreatment: Remove the oil stain on the surface of the nut stud. S2. Laser cladding: Use a laser to perform laser cladding on the added cobalt-based alloy powder. Furthermore, the material of the nut stud is G35CrNiMo6 - 6 + QT1 steel.

[0017] Furthermore, the treatment method for removing the oil stain on the surface of the nut stud in S1 is laser cleaning.

[0018] Furthermore, the process parameters of laser cleaning are: The laser energy density < 200.6 J / cm 2 ; The laser spot is 0.5 - 0.7 mm; The cleaning speed is 80 - 120 mm / s; The scanning width is 70 - 80 mm; The scanning speed is 7000 - 9000 mm / s; The number of scanning times is 1 - 3 times; The spot mode is a linear mode, the defocus amount is 0, the frequency is 2 kHz, and the incident angle is 45°.

[0019] Furthermore, the process parameters of laser cladding in S2 are as follows: The laser power is 2200 - 2800 W; The scanning speed is 20 - 30 mm / s; The powder feeding rate is 17 - 20 g / min; The protective gas flow rate is 5 - 7 L / min; The powder feeding gas flow rate is 6 - 8 L / min; The spot diameter is 2.0 - 2.2 mm.

[0020] Furthermore, a transmissive laser cladding head is adopted, with the collimation C = 90 - 110 mm, the focusing f = 300 - 400 mm, and the powder focus of the cladding nozzle f = 14 - 16 mm.

[0021] The present invention has the following beneficial effects: Using the cobalt - based alloy powder provided by the present invention for laser cladding on the surface of the nut column material G35CrNiMo6 - 6 + QT1 steel, a cladding layer with good bonding effect, high hardness, and excellent anti - wear performance can be obtained. Moreover, there are no defects such as cracks, pores, and inclusions on the surface and inside of the cladding layer. The average Vickers hardness can reach 434.3 Hv (410 HB). Under a 1 N load, its wear volume is all within 0.2×10 7 μm 3 Hereinafter, under a 10 N load, its wear volume is all within 1.3×10 7 μm 3 Hereinafter, under a 30 N load, its wear volume is all within 4.5×10 7 μm 3 Hereinafter, it has excellent mechanical properties and high wear - resistance, has significant advantages in improving the surface properties of materials, and its comprehensive performance fully meets the repair requirements of the nut column in the vertical ship lift. At the same time, it is also applicable to various repair scenarios requiring high hardness and wear resistance. Description of the Drawings

[0022] Figure 1Metallographic structure diagrams of the cladding interface quality of cobalt-based alloy powders in Examples 1-3 and Comparative Examples 1-3 under different laser powers; Figure 2 Metallographic structure diagrams of the cladding interface quality of iron-based alloy powders in Comparative Examples 4-9 under different laser powers; Figure 3 Metallographic structure diagrams of the cladding interface quality of nickel-based alloy powders in Comparative Examples 12-17 under different laser powers; Figure 4 Microhardness change diagrams of the cladding layer to the substrate in Example 1 and Comparative Example 8; Figure 5 Schematic diagrams of the wear volume comparison of Example 1, 4, 5 and Comparative Examples 8, 10, 11 under a 1 N load; Figure 6 Schematic diagrams of the wear volume comparison of Example 1, 4, 5 and Comparative Examples 8, 10, 11 under a 10 N load; Figure 7 Schematic diagrams of the wear volume comparison of Example 1, 4, 5 and Comparative Examples 8, 10, 11 under a 30 N load. Detailed implementation manners

[0023] The principles and features of the present invention will be described below with reference to the accompanying drawings. The examples given are only for explaining the present invention and are not intended to limit the scope of the present invention. For those not specified in the examples, conventional conditions or conditions recommended by the manufacturer are used. Reagents or instruments not specified by the manufacturer are all conventional products that can be obtained through commercial purchase.

[0024] Example 1: A cobalt-based alloy powder, according to the elemental composition, includes the following components in mass percentage: 0.25% C, 2.0% Si, 2.0% Fe, 27.5% Cr, 5.5% Mo, 1.0% Mn, 0.15% W, 2.5% Ni, and the balance is Co and unavoidable impurities; the particle size of the cobalt-based alloy powder is 100-325 μm.

[0025] On the other hand, this example provides an application of a cobalt-based alloy powder. Using the above cobalt-based alloy powder as the cladding material and G35CrNiMo6-6+QT1 cast steel as the base metal component with a size of 200*200*10 (mm), a laser cladding test is carried out. The specific steps are as follows: S1. Pretreatment: Use a CO2 laser to remove the oil stain on the surface of the metal component. The process parameters for laser cleaning are configured as: laser energy density < 200.6 J / cm 2, the laser spot is 0.6 mm, the cleaning speed is 100 mm / s, the scanning width is 75 mm, the scanning speed is 8000 mm / s, the number of scans is 1 time, the spot mode is linear mode, the defocus amount is 0, the frequency is 2 kHz, and the incident angle is 45°. After this process cleaning, there is no obvious remelting layer and rust layer on the section; S2. Laser cladding: Use a laser (Raycus 6000W) and add cobalt-based alloy powder for laser cladding. The process parameters configured for laser cladding are as follows: the laser power is 2500 W, the scanning speed is 20 mm / s, the powder feeding rate is 18.5 g / min, the protective gas flow rate is 6 L / min, the powder feeding gas flow rate is 7 L / min, the fiber length is 20 m, the fiber core diameter is 600 μm, a transmissive laser cladding head is used, the collimation C = 100 mm, the focusing f = 350 mm, and the powder focus of the cladding nozzle f ≈ 15 mm; the theoretical diameter of the focused spot D ≈ 2.1 mm.

[0026] Example 2 - 3: A cobalt-based alloy powder, according to the elemental composition, includes the following components in mass percentages: 0.25% C, 2.0% Si, 2.0% Fe, 27.5% Cr, 5.5% Mo, 1.0% Mn, 0.15% W, 2.5% Ni, and the balance is Co and inevitable impurities; the particle size of this cobalt-based alloy powder is 100 - 325 μm.

[0027] On the other hand, this example provides an application of a cobalt-based alloy powder. The specific treatment steps are the same as those in Example 1. Among them, the laser powers in the S2. Laser cladding step are 2200 W (Example 2) and 2800 W (Example 3) respectively, and other process parameters are consistent with those in Example 1.

[0028] Example 4: A cobalt-based alloy powder, according to the elemental composition, includes the following components in mass percentages: 0.5% C, 2.5% Si, 2.5% Fe, 28.0% Cr, 6.0% Mo, 1.5% Mn, 4.5% W, 5.5% Ni, and the balance is Co and inevitable impurities; the particle size of this cobalt-based alloy powder is 100 - 325 μm.

[0029] On the other hand, this example provides an application of the above cobalt-based alloy powder. The specific treatment steps are the same as those in Example 1. Among them, the scanning speed in the S2. Laser cladding step is 25 mm / s, and other process parameters are consistent with those in Example 1.

[0030] Example 5: A cobalt-based alloy powder, according to the elemental composition, includes the following components in mass percentages: 0.35% C, 3.0% Si, 3.0% Fe, 29.5% Cr, 6.5% Mo, 3.0% Mn, 6.5% W, 10.0% Ni, the balance being Co and inevitable impurities; the particle size of the cobalt-based alloy powder is 100 - 325 μm.

[0031] On the other hand, this embodiment provides an application of the above cobalt-based alloy powder. The specific treatment steps are the same as those in Embodiment 1. Among them, in step S2. Laser cladding step, the scanning speed is 30 mm / s, and other process parameters are consistent with those in Embodiment 1.

[0032] Comparative Examples 1 - 3: A cobalt-based alloy powder, according to the elemental composition, includes the following components in mass percentages: 0.25% C, 2.0% Si, 2.0% Fe, 27.5% Cr, 5.5% Mo, 1.0% Mn, 0.15% W, 2.5% Ni, the balance being Co and inevitable impurities; the particle size of the cobalt-based alloy powder is 100 - 325 μm.

[0033] On the other hand, this comparative example provides an application of the cobalt-based alloy powder. Among them, in step S2. Laser cladding step, the laser powers are 1300 W (Comparative Example 1), 1600 W (Comparative Example 2), and 1900 W (Comparative Example 3) respectively, and other process parameters are consistent with those in Embodiment 1.

[0034] Comparative Examples 4 - 9: An iron-based alloy powder, according to the elemental composition, includes the following components in mass percentages: 0.2% C, 1.2% Si, 28% Cr, 4.5% Mo, 1.0% Mn, 16% Ni, the balance being Fe and inevitable impurities; the particle size of the iron-based alloy powder is 45 - 150 μm.

[0035] On the other hand, this comparative example provides an application of the iron-based alloy powder. The specific treatment steps are the same as those in Embodiment 1. Among them, in step S2. Laser cladding step, the laser powers are 1300 W (Comparative Example 4), 1600 W (Comparative Example 5), 1900 W (Comparative Example 6), 2200 W (Comparative Example 7), 2500 W (Comparative Example 8), and 2800 W (Comparative Example 9) respectively, and other process parameters are consistent with those in Embodiment 1.

[0036] Comparative Example 10: A ferrous-based alloy powder, according to the elemental composition, includes the following components by mass percentage: 0.2% C, 1.2% Si, 28% Cr, 4.5% Mo, 1.0% Mn, 16% Ni, the balance being Fe and inevitable impurities; the particle size of the ferrous-based alloy powder is 45 - 150 μm.

[0037] On the other hand, this comparative example provides an application of the above ferrous-based alloy powder. The specific treatment steps are the same as those in Example 1. Among them, in S2. the scanning speed in the laser cladding step is 25 mm / s, and other process parameters are consistent with those in Example 1.

[0038] Comparative Example 11: A ferrous-based alloy powder, according to the elemental composition, includes the following components by mass percentage: 0.2% C, 1.2% Si, 28% Cr, 4.5% Mo, 1.0% Mn, 16% Ni, the balance being Fe and inevitable impurities; the particle size of the ferrous-based alloy powder is 45 - 150 μm.

[0039] On the other hand, this comparative example provides an application of the above ferrous-based alloy powder. The specific treatment steps are the same as those in Example 1. Among them, in S2. the scanning speed in the laser cladding step is 30 mm / s, and other process parameters are consistent with those in Example 1.

[0040] Comparative Examples 12 - 17: A nickel-based alloy powder, according to the elemental composition, includes the following components by mass percentage: 0.12% C, 0.5% Si, 3% Fe, 15.5% Cr, 16% Mo, the balance being Ni and inevitable impurities; the particle size of the nickel-based alloy powder is 100 - 270 μm.

[0041] On the other hand, this comparative example provides an application of a ferrous-based alloy powder. The specific treatment steps are the same as those in Example 1. Among them, in S2. the laser powers in the laser cladding step are 1300 W (Comparative Example 12), 1600 W (Comparative Example 13), 1900 W (Comparative Example 14), 2200 W (Comparative Example 15), 2500 W (Comparative Example 16), 2800 W (Comparative Example 17) respectively, and other process parameters are consistent with those in Example 1.

[0042] Test Example: The specimens obtained by single-pass laser cladding of Examples 1-3, Comparative Examples 1-9 and Comparative Examples 12-17 at laser powers of 1300 W, 1600 W, 1900 W, 2200 W, 2500 W and 2800 W were cut, embedded, ground and polished according to the standard metallographic preparation method. The cross-sectional quality of the cladding layer at different powers was analyzed and characterized by an optical microscope to obtain the metallographic structure diagram of the cladding layer cross-section, as shown in Figures 1-3 shown ( Figure 1 : cobalt-based alloy powder cladding layer, Figure 2 : iron-based alloy powder cladding layer, Figure 3 : nickel-based alloy powder cladding layer).

[0043] It can be seen from the figure that the bonding effect between the cladding layer and the substrate after cladding of cobalt-based and iron-based alloy powders at powers of 1300 W, 1600 W and 1900 W is poor, and there are a large number of defects such as pores, inclusions and poor wettability with the substrate. In contrast, at powers of 2200 W, 2500 W and 2800 W, with the continuous increase of the laser power, the above defects are gradually alleviated or disappear, the cladding layer is continuously and densely bonded to the substrate and the cladding width increases, and no defects such as pores and unmelted are seen; but at the same time, the heat-affected zone of the substrate at the interface gradually increases, and there is a phenomenon of powder sticking in the cladding layer at 2200 W. Therefore, based on the comprehensive comparative analysis of the cladding layer quality and the heat-affected zone, the cladding effect is the best at a power of 2500 W; subsequently, Examples 1, 4, 5 of cobalt-based alloy powder and iron-based alloy powder cladding at 2500 W power and Comparative Examples 8, 10, 11 were selected to continue the hardness and friction and wear performance test experiments to further analyze the performance of their cladding layers.

[0044] After laser cladding of nickel-based alloy powder at each power, there are a large number of pores and inclusions in the cross-section, and obvious cracking is observed at 2800 W. Therefore, nickel-based alloy powder is not suitable for the substrate repair process of the present invention, and no subsequent performance tests are carried out.

[0045] The microhardness of the substrate and the cladding layer was measured using a micro-Vickers hardness tester (DHV-1000ZTEST) with a load of 200 gN and a holding time of 15 s. Examples 1 and Comparative Example 8 were tested, and the average value of 10 points at each test position of each specimen was taken as the experimental result. Taking the position at the abscissa 0 as the junction between the cladding layer and the substrate, the positive number (right side of 0) region is the cladding layer region, and the negative number (left side of 0) region is the substrate region. The average Vickers hardness of the cladding layer is taken as the final hardness value. Figure 4It is the microhardness change diagram from the substrate to the cladding layer of Example 1 and Comparative Example 8. It can be seen from the figure that the average Vickers hardness of the cladding layer prepared in Example 1 of the present invention is 434.3 Hv (410 HB), and the average Vickers hardness of the cladding layer prepared in Comparative Example 8 is 334.1 Hv (320 HB). The hardness of the cobalt-based alloy powder cladding layer is much higher than that of the iron-based alloy powder, and it meets the requirement that the surface hardness of the repaired position is not lower than 230 HB after repair.

[0046] The cladding specimens obtained from Example 1, Examples 4 - 5, Comparative Example 8 and Comparative Examples 10 - 11 were carried out sliding friction and wear tests on a high-precision tangential sliding reciprocating friction and wear test equipment. The contact mode was ball-plane mode. A GCr15 steel ball with a diameter of 10 mm and a hardness of 700 Hv was selected as the counterbody. The specimen size for the sliding friction and wear test was 15 mm × 10 mm × 2.5 mm, and it was cut, embedded, polished and polished according to the standard metallographic preparation method. The sliding friction and wear tests were all carried out at room temperature and in the atmospheric environment, with a displacement amplitude of 2.5 mm, normal loads of 1 N, 10 N and 30 N respectively, a test frequency of 2 Hz, and a cycle number of 1×10 4 , and the relative humidity was 50% - 60%. The direction of the sliding friction and wear test was perpendicular to the laser cladding direction of the sample. All working conditions were repeated three times to ensure the repeatability of the test and the accuracy of the data. After the sliding friction and wear test was completed, a Bruker white light interference 3D profiler (GTK - 16 - 0295) was used to collect the wear volume and the two-dimensional profile of the wear scar of the specimen after the wear test, and then analyze the anti-wear performance of the cladding layer. To avoid the irregular shape at both ends of the wear scar affecting the experimental results, when calculating the wear volume of all specimens, a 4 mm long area in the center of the wear scar (the total length of the wear scar was 5 mm) was selected, and the wear volume was used as the evaluation index for wear resistance.

[0047] The experimental results are as Figures 5-7 ( Figure 5 : the load is 1 N, Figure 6 : the load is 10 N, Figure 7 : the load is 30 N) and shown in Table 1.

[0048] Table 1 Friction and wear test results under different loads

[0049] From Figures 5-7 and the data in Table 1, it can be known that the wear volumes of the cladding specimens of Examples 1, 4, and 5 under each load of the present invention are much smaller than those of Comparative Examples 8, 10, and 11, indicating that the cladding layer prepared from cobalt-based alloy powder has significantly excellent anti-wear performance and can be used for the repair of the nut column in the vertical ship lift.

[0050] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

Claims

1. A cobalt-based alloy powder, characterized in that: The cobalt-based alloy powder includes the following components in percentage by mass according to elemental composition: 0.2-0.6% C, 2.0-3.0% Si, 2.0-3.0% Fe, 25.0-32.0% Cr, 5.0-7.0% Mo, 1.0-3.0% Mn, 0.1-9.0% W, 2.0-12.0% Ni, and the balance is Co and unavoidable impurities.

2. The cobalt-based alloy powder according to claim 1, characterized in that The cobalt-based alloy powder includes the following components in percentage by mass according to element composition: 0.25% C, 2.0% Si, 2.0% Fe, 27.5% Cr, 5.5% Mo, 1.0% Mn, 0.15% W, 2.5% Ni, the balance is Co and inevitable impurities.

3. The cobalt-based alloy powder according to claim 1 or 2, characterized in that: The particle size of the cobalt-based alloy powder is 100-325 μm.

4. Use of the cobalt-based alloy powder according to any one of claims 1 to 3 in repairing nut columns.

5. The use according to claim 4, characterized in that: The repair method is laser cladding, and the specific steps of laser cladding are: S1. Pretreatment: remove oil stains on the surface of the nut column; S2. Laser cladding: using a laser to perform laser cladding on the cobalt-based alloy powder.

6. The use according to claim 5, characterized in that: The material of the nut column is G35CrNiMo6-6+QT1.

7. The use according to claim 5, characterized in that: The method for removing oil stains on the surface of the nut column in S1 is laser cleaning.

8. The use according to claim 5, characterized in that: The process parameters of the laser cleaning are: Laser energy density <200.6 J / cm 2 ; The laser spot is 0.5~0.7 mm; The cleaning speed is 80~120 mm / s; Scan width is 70~80 mm; Scanning speed is 7000~9000 mm / s; The number of scans is 1 to 3 times; The spot pattern is a straight line pattern, the defocus is 0, the frequency is 2 kHz, and the incident angle is 45°.

9. The use according to claim 5, characterized in that: The process parameters of laser cladding in S2 are: Laser power is 2200~2800 W; Scanning speed is 20~30 mm / s; The powder feeding rate is 17~20 g / min; Shielding gas flow rate 5~7 L / min; Powder delivery gas flow rate 6~8 L / min; The spot diameter is 2.0~2.2 mm.

10. The use according to claim 9, characterized in that: A transmission laser cladding head is used, with collimation C=90~110mm, focusing f=300~400 mm, and cladding nozzle powder coke f=14~16 mm.

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