A laser cladding remanufacturing strengthening method

Abstract

This invention belongs to the field of laser additive manufacturing technology, specifically materials science and surface engineering technology. It relates to a laser cladding remanufacturing strengthening method, comprising the following steps: surface pretreatment of the coupling; high-speed laser cladding of the pretreated coupling, wherein the cladding layer is designed as a multi-layer, multi-pass cladding, with the chromium content concentration in the cladding layer increasing sequentially from the inside to the outside, and the thickness of each pass also increasing sequentially from the inside to the outside, with the chromium concentration increasing by 0% to 15% in each pass. This method applies a high-hardness, gradient, chromium-rich wear-resistant layer to the outer surface of the coupling via laser cladding. The cladding layer forms a metallurgical, dense bond with the substrate, exhibiting high bonding strength and hardness, which improves the wear resistance of the coupling, making it less prone to detachment during long-term operation and extending the service life of the workpiece.

Description

Technical Field

[0001] This invention belongs to the field of laser additive manufacturing technology, specifically relating to a laser cladding remanufacturing strengthening method. Background Technology

[0002] With rapid economic development, the working environment of equipment components in various industries is becoming increasingly complex. This is especially true for critical parts of wear-resistant and corrosion-resistant components, where the performance requirements for surfaces and interfaces are becoming increasingly stringent. During long-term service, components may experience performance degradation or even damage due to wear, corrosion, and extreme environments, leading to an increased probability of component failure. Common components scrapped due to surface failure include rotor blades, shafts, gears, and molds. If these critical components are repaired promptly in the early stages of damage, they can return to their original working condition. Laser cladding can not only repair critical components damaged by long-term service but also optimize existing manufacturing processes. For example, it can directly remanufacture and strengthen parts of equipment components with special requirements, extending the service life of workpieces while meeting current operating conditions and effectively improving resource utilization.

[0003] In recent years, chromium has become an indispensable alloying element in various wear-resistant and corrosion-resistant alloy materials. Chromium possesses excellent high-temperature oxidation resistance, and hard chromium plating not only has a high melting point and good chemical stability but also high hardness, resisting wear and deformation caused by long-term operation. Currently, electroplating is a commonly used method in industry. Although electroplated chromium layers are low-cost and have good hardness and uniformity, the bonding between the hard chromium plating layer and the substrate material is essentially a physical bond, resulting in poor adhesion. Long-term use can easily lead to bubbling, oxidation, cracking, and other issues that cause the plating to fail. Furthermore, electroplating chromium also causes significant environmental pollution. Summary of the Invention

[0004] In view of the shortcomings of the prior art, one of the objectives of this invention is to solve one or more problems existing in the prior art. For example, one objective of this invention is to provide a laser cladding remanufacturing strengthening method for coupling surfaces that ensures a strong bond between the cladding layer and the substrate, while the overall cladding layer meets hardness requirements, thereby strengthening the workpiece surface and extending its service life.

[0005] Specifically, this invention addresses the remanufacturing, repair, and strengthening of 40Cr coupling-type workpieces. It proposes a more practical laser cladding chromium-rich coating technology that can replace electroplated hard chromium plating. Couplings are mechanical components that firmly connect the driving and driven shafts in mechanical equipment, transmitting power and torque. Long-term use can lead to surface and interface damage due to wear, erosion, and oxidation. The laser cladding layer produced by this invention exhibits superior hardness, wear resistance, corrosion resistance, and thermal properties. It also saves raw materials, is pollution-free, and offers advantages over electroplating chromium plating, including being environmentally friendly, having a dense cladding layer, and high bonding strength with the substrate. The cladding layer achieves a metallurgical bond with the substrate, minimizing cracks and porosity, enhancing the bonding strength, and significantly extending the service life of components. Furthermore, the addition of a certain amount of chromium to the alloy powder not only reduces the need for pure chromium plating but also improves corrosion resistance and bonding strength with the substrate while ensuring the cladding layer's hardness meets requirements. The method of the present invention laser-coats a chromium-rich coating on the outer surface of the coupling. The coating is applied in multiple layers and multiple passes, with the chromium content increasing in a gradient. This allows the coating to bond more firmly to the substrate, while the overall cladding layer meets certain hardness requirements, thereby strengthening the workpiece surface and extending its service life.

[0006] This invention proposes a laser cladding remanufacturing strengthening method, which may include the following steps:

[0007] Step S01, coupling surface pretreatment. For example, high-speed laser cladding technology can be used to perform laser surface pretreatment on the outer surface of the coupling workpiece to remove contaminants, rust spots, and submicron-sized impurity particles, and then a high-hardness wear-resistant coating is clad onto the clean workpiece surface.

[0008] Step S02: High-speed laser cladding is performed on the pre-treated coupling. The cladding layer is designed as a multi-layer, multi-pass cladding. The chromium content concentration in the cladding layer increases from the inside to the outside, and the thickness of each pass also increases from the inside to the outside. The chromium concentration of each pass increases from 0% to 15%. The mass percentage range of each component element in the cladding layer can be as follows: C: 0.2-0.5wt%, Si: 0.3-0.5wt%, Cr: 10.5-35.6wt%, Mn: 0.4-0.5wt%, Co: 0.1-0.5wt%, Ni: 0.1-0.8wt%, V: 0-0.3wt%, Mo: 0-12wt%, with the balance being Fe. For example, the mass percentage range of each component element in the cladding layer can be as follows: C: 0.25-0.4wt%, Si: 0.35-0.42wt%, Cr: 12.5-30.5wt%, Mn: 0.42-0.48wt%, Co: 0.2-0.4wt%, Ni: 0.3-0.6wt%, V: 0-0.25wt%, Mo: 0-11wt%, with the balance being Fe. Alternatively, the mass percentage range of each component element in the cladding layer can be as follows: C: 0.32-0.38wt%, Si: 0.37-0.40wt%, Cr: 20.5-27.2wt%, Mn: 0.44-0.47wt%, Co: 0.25-0.38wt%, Ni: 0.4-0.52wt%, V: 0-0.19wt%, Mo: 0-9.2wt%, with the balance being Fe. Preferably, the chromium concentration of each cladding layer increases by 2% to 15%. By cladding in an increasing order of chromium concentration from the inside out, and with the thickness of each cladding layer also increasing from the inside out, the inner cladding layer can be made to have a more similar alloy content to the 40Cr base material of the coupling, while simultaneously increasing the hardness of the outer cladding layer and improving wear resistance. For example, the chromium concentration increase for each cladding layer can be a combination of 3%–14%, 5%–10%, 6%–12%, 8%–9%, ​​or higher. High-speed laser cladding is performed by adjusting and optimizing cladding parameters such as laser power, spot size, linear velocity, and overlap rate. Argon powder blowing and coaxial lateral powder feeding are used to laser clad a high-hardness gradient chromium-rich wear-resistant layer on the outer surface of the coupling. For example, the thickness of the cladding layer can be 2, 3, or more layers.

[0009] Furthermore, high-speed laser cladding parameters can include: laser power controlled between 1500W and 3500W, a circular spot diameter of 4mm to 10mm, a multi-pass cladding overlap rate of 40% to 70%, a scanning rate of 20mm / s or higher, and the use of argon gas blowing and coaxial lateral powder feeding for high-speed laser cladding of the coupling surface. For example, the laser power can be 1800W to 3200W, the circular spot diameter 6mm, the multi-pass cladding overlap rate 50% to 65%, and the scanning rate 25mm / s to 40mm / s. Another example is a laser power of 2000W to 2800W, a circular spot diameter 6.5mm, a multi-pass cladding overlap rate 52% to 63%, and a scanning rate 31mm / s to 38mm / s.

[0010] Furthermore, the thickness of a single cladding layer is 0.1mm-0.8mm, and the thickness of the first cladding layer is no greater than the thickness of the other cladding layers. For example, the thickness increase of each layer can be 0.2mm-0.5mm, or, for another example, 0.3mm.

[0011] Furthermore, high-speed laser cladding also includes heat preservation during the cladding process, with the temperature ranging from 40℃ to 90℃. For example, the temperature can be 50℃, 60℃, 70℃, or 80℃. This ensures that the temperature generated during laser cladding does not decrease, allowing for temperature measurement using a contact thermometer and the use of insulation materials such as insulating cotton.

[0012] Furthermore, high-speed laser cladding also includes the requirement for slow cooling of the cladding coating, with a cooling rate ranging from 3°C / h to 8°C / h. For example, the cooling rate can be 4°C / h, 5°C / h, 6°C / h, or 7°C / h.

[0013] Furthermore, the surface pretreatment of the coupling includes laser surface treatment, with a laser power of 500-1500W. For example, the surface treatment laser power can be 1000W.

[0014] Furthermore, the coupling is made of 40Cr, and its outer surface is cylindrical or conical.

[0015] Furthermore, the high-speed laser cladding process includes drying the cladding powder beforehand. The drying temperature is between 100℃ and 140℃, and the drying time is between 40 minutes and 2 hours. For example, the drying temperature can be 120℃, and the drying time can be 1 hour.

[0016] Furthermore, after high-speed laser cladding, the hardness of the cladding layer ranges from HRC43 to 55.

[0017] Furthermore, the specific steps of high-speed laser cladding may include:

[0018] (1) Pretreatment: Adjust the laser power to 1000W, remove oil and rust from the surface of the coupling, dry the substrate, and dry the raw material powder to be clad at 120℃ for 1 hour.

[0019] (2) Laser parameters: The laser power of the laser cladding process is controlled between 1500W and 3500W, the diameter of the circular spot is 6mm, the overlap rate of multi-pass cladding is between 40% and 70%, and the scanning speed is above 20mm / s.

[0020] (3) The laser cladding process adopts coaxial side powder feeding and argon powder blowing. The single-pass cladding thickness is 0.1mm-0.8mm. The number of cladding layers can be set according to the workpiece thickness requirements. The chromium concentration of each cladding layer increases by 10% to 15%. The thickness of the first cladding layer is not greater than that of other layers.

[0021] (4) The cladding process needs to be kept warm, that is, the temperature generated during the laser cladding process should not drop. Insulation cotton and other measures can be used to keep warm. The temperature generated during the laser cladding process should not drop. A contact thermometer can be used to measure the temperature. The temperature range should be kept between 40-90℃. After cladding, the coating needs to be cooled slowly. The cooling rate range is 3-8℃ / h.

[0022] The laser cladding coating has an average roughness between 0.2 and 3.5 μm before finishing. After laser cladding strengthening, the hardness of the outer surface of the coupling can be increased by more than 30%. The coating forms a metallurgical-like dense bond with the substrate, with high bonding strength and high hardness, which can improve the wear resistance of the coupling, making it less prone to peeling off under long-term operation and extending the service life of the workpiece.

[0023] The beneficial effects of the present invention include at least the following: the method of the present invention enables the cladding layer to form a metallurgical dense bond with the substrate, with high bonding strength and high hardness, which can improve the wear resistance of the coupling, making it less likely to fall off under long-term operation and extending the service life of the workpiece. Attached Figure Description

[0024] Figure 1 Comparison of the cladding and uncladding areas of a cylindrical sample subjected to high-speed laser cladding;

[0025] Figure 2 Example image of a coupling whose outer surface has been reinforced by laser cladding and then machined. Detailed Implementation

[0026] The present invention is further described below through specific embodiments:

[0027] Example 1

[0028] Laser remanufacturing was performed on the outer surface of the coupling workpiece. The substrate material was 40Cr with a hardness of HRC36. After laser cladding, the surface hardness of the workpiece was increased to achieve high wear resistance. First, a 1000W laser was used to remove oil and rust from the areas to be strengthened on the coupling surface, and then the surface was dried. The raw material powder to be clad was dried at 120℃ for 1 hour. The mass percentage range of the raw material composition to be clad is as follows: C: 0.3wt%, Si: 0.3wt%, Cr: 11wt%, Mn: 0.4wt%, Co: 0.1wt%, Ni: 0.2wt%, V: 0.1wt%, Mo: 0.3wt%. 2.2wt%, balance Fe; the laser cladding process uses coaxial lateral powder feeding and argon powder blowing. The number of cladding layers is set to three: the inner layer cladding thickness is 0.2mm, the chromium content is 11wt%, and each layer increases by 10%; the middle layer cladding thickness is 0.5mm, and the outer layer thickness is 0.8mm. The laser power during the laser cladding process is controlled at 2700W, the diameter of the circular spot is 6mm, the overlap rate is 45%, and the scanning rate is 20mm / s. The cladding process requires heat preservation, meaning the temperature generated during laser cladding must not decrease. A contact thermometer can be used to measure the temperature, which should be maintained within 80℃. Insulation cotton or other measures can be used for heat preservation. After cladding, the coating needs to be slowly cooled at a rate of 3℃ / h. The average roughness of the cladding coating before subsequent finishing is Ra0.4. After laser cladding strengthening, the hardness of the outer surface of the coupling is HRC50, which is 38.9% higher than the hardness of the substrate.

[0029] Example 2

[0030] Laser remanufacturing was performed on the outer surface of the coupling workpiece. The substrate material was 40Cr with a hardness of HRC36. After laser cladding, the surface hardness of the workpiece was increased to achieve high wear resistance. First, a 1000W laser was used to remove oil and rust from the areas of the coupling surface to be strengthened, and then the surface was dried. The raw material powder to be clad was dried at 120℃ for 1 hour. The mass percentage range of the raw material composition to be clad is as follows: C: 0.2wt%, Si: 0.3wt%, Cr: 12.1wt%, Mn: 0.4wt%, Co: 0.2wt%, Ni: 0.1wt%, V: 0.2wt%, Mo: 0.2wt%. The chromium content is 2.8 wt%, with the balance being Fe. The laser cladding process uses coaxial lateral powder feeding and argon blowing. Two cladding layers are used: the inner layer is 0.5 mm thick with a chromium content of 12.1 wt%, increasing by 10% with each subsequent layer; the outer layer is 0.8 mm thick. The laser power is controlled at 2800 W, the circular spot diameter is 6 mm, the overlap rate is 60%, and the scanning speed is 30 mm / s. Temperature preservation is required during the cladding process to prevent temperature drop. A contact thermometer can be used to measure the temperature, which should be maintained within 75℃. Insulation measures such as insulating cotton can be used. After cladding, the coating needs slow cooling at a rate of 5℃ / h. The average roughness of the cladding coating before subsequent finishing is Ra0.3. After laser cladding strengthening, the hardness of the coupling's outer surface is HRC48, which is 33.3% higher than the substrate hardness. Figure 1 This is a comparison image of the clad and unclad areas when using this parameter to perform laser cladding on a cylindrical sample.

[0031] Example 3

[0032] Laser remanufacturing was performed on the outer surface of the coupling workpiece. The substrate material was 40Cr with a hardness of HRC32. After laser cladding, the surface hardness of the workpiece was increased to achieve high wear resistance. First, a 1000W laser was used to remove oil and rust from the areas of the coupling surface to be strengthened, and then the surface was dried. The raw material powder to be clad was dried at 120℃ for 1 hour. The mass percentage range of the raw material composition to be clad is as follows: C: 0.4wt%, Si: 0.3wt%, Cr: 15wt%, Mn: 0.4wt%, Co: 0.1wt%, Ni: 0.5wt%, Mo ... Co: 0.4wt%, Co: 0.1wt%, Mo: 0.5wt%, Mo: 0.4wt%, Co: 0.4wt%, Co: 0.1wt%, Co: 0.5wt%, Mo: 0.4wt%, Co: 0.4wt%, Co: 0.4wt%, Co: 0.4wt%, Co: 0.4wt%, Co: 0.4wt%, Co: 0.4wt%, Co: 0.4wt%, Co: 0.4wt%, Co: 0.4wt%, Co: 0.4wt%, Co: 0.4wt%, Co: 0.4wt%, Co: 0.4wt%, The chromium content is 5 wt%, with the balance being Fe. The laser cladding process uses coaxial lateral powder feeding and argon blowing. Four cladding layers are used, with the inner layer having a thickness of 0.2 mm and a chromium content of 15 wt%. Each subsequent layer increases by 10%, with the second layer having a thickness of 0.5 mm and all subsequent layers having a thickness of 0.8 mm. The laser power during the laser cladding process is controlled at 2500 W, the diameter of the circular spot is 6 mm, the overlap rate is 70%, and the scanning rate is 20 mm / s. Temperature preservation is required during the cladding process to prevent the temperature from dropping. A contact thermometer can be used to measure the temperature, which should be maintained within the range of 85℃. Insulation measures such as insulating cotton can be used for preservation. After cladding, the coating needs to be slowly cooled at a rate of 8℃ / h. The average roughness of the cladding coating before subsequent finishing is Ra0.5. After laser cladding strengthening, the hardness of the coupling's outer surface is HRC45, which is 40.6% higher than the hardness of the substrate.

[0033] Example 4

[0034] Laser remanufacturing was performed on the outer surface of the coupling workpiece. The substrate material was 40Cr with a hardness of HRC32. After laser cladding, the surface hardness of the workpiece was increased to achieve high wear resistance. First, a 1000W laser was used to remove oil and rust from the areas of the coupling surface to be strengthened, and then the surface was dried. The raw material powder to be clad was dried at 120℃ for 1 hour. The mass percentage range of the raw material composition to be clad is as follows: C: 0.2wt%, Si: 0.3wt%, Cr: 25wt%, Mn: 0.4wt%, Co: 0.1wt%, Ni: 0.2wt%, V: 0.3wt%, Mo: 0.2wt%, Ni: 0.2wt%, V: 0.3wt%, Mo: 0.3wt%. The chromium content is 5 wt%, with the balance being Fe. The laser cladding process uses coaxial lateral powder feeding and argon blowing. The cladding layer is set to three layers: the inner layer has a thickness of 0.5 mm and a chromium content of 25 wt%, increasing by 10% with each subsequent layer; the middle layer has a thickness of 0.6 mm; and the outer layer has a thickness of 0.8 mm. The laser power during the laser cladding process is controlled at 2500 W, the diameter of the circular spot is 6 mm, the overlap rate is 70%, and the scanning rate is 28 mm / s. Temperature preservation is required during the cladding process to prevent the temperature from dropping. A contact thermometer can be used to measure the temperature, which should be maintained within 60℃. Insulation measures such as insulating cotton can be used for preservation. After cladding, the coating needs to be slowly cooled at a rate of 5℃ / h. The average roughness of the clad coating before subsequent finishing is Ra0.4. After laser cladding strengthening, the hardness of the coupling's outer surface is HRC43, which is 34.4% higher than the hardness of the substrate. Figure 2 This is an example of a coupling whose outer surface has been reinforced by laser cladding and then machined.

Claims

1. A laser cladding remanufacturing strengthening method, characterized in that, Includes the following steps: High-speed laser cladding is performed on the coupling. The cladding layer is designed as a multi-layer, multi-pass cladding, with the chromium concentration increasing sequentially from the inside out. The thickness of each cladding layer also increases sequentially from the inside out. The chromium concentration of each cladding layer increases by 2% to 15% in each subsequent layer. The mass percentage range of each component element in the cladding layer is as follows: C: 0.2-0.5 wt%, Si: 0.3-0.5 wt%, Cr: 10.5-35.6 wt%, Mn: 0.4-0.5 wt%, Co: 0.1-0.5 wt%, Ni: 0.1-0.8 wt%, V: 0-0.3 wt%, Mo: 0-12 wt%, with the balance being Fe; The coupling is made of 40Cr, and its outer surface is cylindrical or conical; after high-speed laser cladding, the hardness of the cladding layer ranges from HRC43 to 55.

2. The laser cladding remanufacturing strengthening method according to claim 1, characterized in that, The parameters for high-speed laser cladding include: laser power controlled between 1500 W and 3500 W, circular spot diameter between 4 mm and 10 mm, multi-pass cladding overlap rate between 40% and 70%, scanning rate above 20 mm / s, and high-speed laser cladding of the coupling surface using argon powder blowing and coaxial side powder feeding.

3. The laser cladding remanufacturing strengthening method according to claim 1 or 2, characterized in that, The thickness of a single cladding layer is 0.1 mm to 0.8 mm, and the thickness of the first cladding layer is no greater than the thickness of the other cladding layers.

4. The laser cladding remanufacturing strengthening method according to claim 1 or 2, characterized in that, High-speed laser cladding also includes heat preservation during the cladding process, with the heat preservation temperature ranging from 40 ℃ to 90 ℃.

5. The laser cladding remanufacturing strengthening method according to claim 1 or 2, characterized in that, High-speed laser cladding also requires the coating to be slowly cooled after cladding, with a cooling rate of 3 ℃ / h-8 ℃ / h.

6. The laser cladding remanufacturing strengthening method according to claim 1 or 2, characterized in that, The surface pretreatment of the coupling includes surface treatment using laser with a laser power of 1000W.

7. The laser cladding remanufacturing strengthening method according to claim 1 or 2, characterized in that, Before high-speed laser cladding, the cladding powder is dried at a temperature of 120°C for 1 hour.

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