A laser deposition repair layer on the surface of a titanium alloy and a repair method

Abstract

The present application provides a laser deposition repair layer on the surface of a titanium alloy and a repair method. In this method, high-purity Fe, Co, Cr, C, and B powders are used as deposition materials, and a TiB2 ceramic phase is in-situ deposited on the surface of the titanium alloy substrate under the irradiation of high-energy laser. This greatly improves the hardness and wear resistance of the deposition repair layer, and further enhances the ability of the deposition repair layer to withstand alternating loads during the wear process, avoiding the generation of cracks in the deposition repair layer. In addition, the deposition repair layer and the titanium alloy substrate have good metallurgical bonding, greatly improving the service life of the repair layer, and are suitable for repairing the service damage of Ti-6Al-4V titanium alloy. The Ti element in the deposition repair layer comes from the titanium alloy bulk material, and there is no need to add Ti powder to the deposition powder; the mixed powder is an iron-based powder with a low price, which all reduces the repair cost of the titanium alloy. This method is simple to operate, and the formed quality of the deposition repair layer is good, which is suitable for mass production.

Description

Technical Field

[0001] The present invention belongs to the technical field of alloy surface treatment, and relates to a laser deposition repair layer on the surface of a titanium alloy and a repair method thereof. Background Art

[0002] Titanium alloy refers to a variety of alloy metals made of titanium and other metals, which have excellent strength-to-weight ratio, high strength, good corrosion resistance, high heat resistance, etc., and have important applications in the fields of aerospace, shipbuilding, chemical engineering, etc.

[0003] Ti-6Al-4V is one of the most common titanium alloys. After long-term service, the components of Ti-6Al-4V titanium alloy will be damaged. Especially under extreme working conditions such as high temperature, high pressure, and heavy load, the wear of titanium alloy components is particularly serious. Therefore, it is necessary to repair them. In order to make the repaired titanium alloy components adapt to extreme working conditions such as high temperature, high pressure, and heavy load, this puts forward higher requirements for the repair quality of titanium alloy.

[0004] When repairing Ti-6Al-4V titanium alloy components by the method of repair welding, due to the large chemical activity of titanium, it is easy to react with elements such as oxygen, nitrogen, and hydrogen at high temperature to form brittle compounds. Due to the low surface energy of titanium alloy, the bonding force of the repair layer prepared on the surface of Ti-6Al-4V titanium alloy is often not strong enough and is easy to peel off, resulting in the inability to guarantee the repair quality. In addition, in the repair of titanium alloy components, problems such as oxidation, cracks, and pores are likely to occur in the repair layer, which makes the repair of Ti-6Al-4V titanium alloy components face great difficulties. Summary of the Invention

[0005] The purpose of the present invention is to provide a laser deposition repair layer on the surface of a titanium alloy and a repair method thereof to solve the problem of easy cracking during the repair of the existing titanium alloy surface.

[0006] To achieve the above purpose, the present invention adopts the following technical solutions:

[0007] The present application provides a laser deposition repair method for the surface of a titanium alloy, and the method includes:

[0008] S01: Put high-purity Fe, Co, Cr, C, and B powders into a ball mill and dry grind them for 2-4 h to obtain a mixed powder with a particle size of 150-300 mesh.

[0009] The high-purity Fe, Co, Cr, C, and B powders are proportioned according to the design requirements and weighed respectively according to the mass percentage. The weighed powders are added to the ball mill and dry ground for 2-4 h to control the particle size of the mixed powder within 150-300 mesh. More preferably, the particle size of the mixed powder is 300 mesh.

[0010] In this application, the mass percentages of Fe, Co, Cr, C, and B powders are as follows: 15 - 25% Co powder, 4 - 8% Cr powder, 1 - 4% C powder, 8 - 12% B powder, and the rest is pure Fe powder. More preferably, the mass percentages of Fe, Co, Cr, C, and B powders are: 15% Co powder, 5% Cr powder, 1% C powder, 10% B powder, and 69% Fe powder.

[0011] S02: After the mixed powder is mixed with absolute ethanol, it is spread flat on the surface of the polished titanium alloy substrate with a thickness of 0.5 - 1 mm.

[0012] The surface of the titanium alloy substrate is polished with 200# SiC sandpaper until it is flat to remove impurities on the substrate surface. After polishing, it is cleaned with acetone. After the acetone cleaning is completed and the surface of the titanium alloy substrate is dry, the mixed powder is mixed with absolute ethanol and then spread flat on the polished titanium alloy substrate surface with a thickness of 0.5 - 1 mm.

[0013] S03: After the titanium alloy substrate is dried at a temperature of 120 - 150 °C for 1 - 2 h, laser deposition is carried out to form a deposited repair layer on the surface of the titanium alloy substrate.

[0014] The titanium alloy substrate with the mixed powder spread flat on its surface is placed in a vacuum drying oven and dried at a temperature of 120 - 150 °C for 1 - 2 h to remove the ethanol in the mixed powder and the moisture on the surface of the titanium alloy substrate. More preferably, the drying temperature of the mixed powder and the titanium alloy substrate is 140 °C and the drying time is 1.5 h.

[0015] After drying, the titanium alloy substrate is placed on the workbench for laser deposition. Among them, the conditions for laser deposition are: laser power: 1100 - 2000 W; scanning speed: 2 - 6 mm / s; spot diameter: 2 - 5 mm; high-purity argon is used as the shielding gas, and the flow rate is set at 10 - 20 L / min. More preferably, the conditions for laser deposition are: laser power: 1500 W; scanning speed: 4 mm / s; spot diameter: 3 mm; high-purity argon is used as the shielding gas, and the flow rate is set at 15 L / min.

[0016] During the laser deposition process, the Fe-Co-Cr-C-B mixed powder and the surface of the titanium alloy substrate are rapidly melted under the action of high-energy laser. The titanium element in the titanium alloy is rapidly diluted into the melted Fe-Co-Cr-C-B alloy deposition layer under the influence of the high-energy laser beam. In the Fe-Co-Cr-C-B mixed powder, due to the lower Gibbs free energy of Ti and B, a deposition repair layer of TiB2 ceramic phase is preferentially synthesized in situ inside the deposition layer. The in-situ synthesized TiB2 ceramic phase is a ceramic phase with extremely high hardness, which can greatly improve the hardness and wear resistance of the deposition repair layer, and further enhance the ability of the deposition repair layer to withstand alternating loads during the wear process. Under the dual influence of the metal toughness of the metal powder and the high hardness of the TiB2 ceramic phase, the wear resistance and crack resistance of the deposition repair layer are greatly improved.

[0017] In this application, the average microhardness of the deposition repair layer is 1300 - 1600 HV, and the average friction coefficient is 0.35 - 0.52. In addition, since the Ti element in the deposition repair layer comes from the titanium alloy base material, there is no need to add Ti powder to the deposition powder, which greatly reduces the repair cost of the titanium alloy. At the same time, the mixed powder is an iron-based powder with a low price, which further reduces the repair cost of the titanium alloy.

[0018] In addition, this application also provides a laser deposition repair layer on the surface of a titanium alloy, and this deposition repair layer is prepared by the above repair method.

[0019] The present invention has the following beneficial effects:

[0020] (1) In this application, high-purity Fe, Co, Cr, C, and B powders are used as deposition materials, and a TiB2 ceramic phase is in-situ deposited on the surface of the titanium alloy substrate under high-energy laser irradiation, which greatly improves the hardness and wear resistance of the deposition repair layer, and further enhances the ability of the deposition repair layer to withstand alternating loads during the wear process.

[0021] (2) Compared with the method of adding TiB2 powder to enhance the performance of the laser deposition layer, this application uses an in-situ deposition method to form a TiB2 ceramic phase on the surface of the titanium alloy substrate, enhancing the hardness and wear resistance of the deposition repair layer, and at the same time can also avoid the generation of cracks in the deposition repair layer.

[0022] (3) The average microhardness of the deposition repair layer is 1300 - 1600 HV, and the average friction coefficient is 0.35 - 0.52.

[0023] (4) The Ti element in the deposition repair layer comes from the titanium alloy base material, and there is no need to add Ti powder to the deposition powder, which greatly reduces the repair cost of the titanium alloy. At the same time, the mixed powder is an iron-based powder with a low price, which further reduces the repair cost of the titanium alloy.

[0024] (5) The processing method adopted in this application is simple to operate, the formed quality of the deposited repair layer is good, and it is suitable for mass production.

[0025] (6) The deposited repair layer formed in this application and the titanium alloy matrix have good metallurgical bonding, which greatly improves the service life of the repair layer and is mainly used for repairing the service damage of Ti-6Al-4V titanium alloy. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is the XRD (X-Ray Diffractometer) detection diagram of the deposited repair layer prepared in Example 1 of this application;

[0027] Figure 2 It is the SEM (Scanning electron microscope) detection diagram of the deposited repair layer prepared in Example 1 of this application;

[0028] Figure 3 It is the Figure 2 elemental distribution diagram in the white frame of the deposited repair layer prepared in Example 1 of this application;

[0029] Figure 4 It is the dry friction coefficient diagram of the deposited repair layer prepared in Example 1 of this application. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0030] The technical solutions of the present invention will be further explained and described below through specific embodiments.

[0031] Example 1

[0032] This application provides a laser deposition repair method for the surface of titanium alloy, and the method includes:

[0033] S101: Weigh high-purity Fe, Co, Cr, C, and B powders according to 15% Co powder, 5% Cr powder, 1% C powder, 10% B powder, and 69% Fe powder by mass percentage. Add the weighed high-purity metal powders into a ball mill and dry grind for 4 h to control the particle size of the mixed powder within 300 mesh.

[0034] S102: Polish the surface of the titanium alloy matrix with 200# SiC sandpaper until it is flat to remove the impurities on the matrix surface. After polishing, clean it with acetone. After the acetone cleaning is completed and the surface of the titanium alloy matrix is dry, mix the mixed powder with absolute ethanol and spread it evenly on the polished surface of the titanium alloy matrix, and the spreading thickness is 1 mm.

[0035] S103: Place the titanium alloy substrate with the mixed powder evenly spread on its surface into a vacuum drying furnace and dry it at 140°C for 1.5 h. After drying, place the titanium alloy substrate on the workbench for laser deposition to obtain a deposited repair layer. Among them, the conditions for laser deposition are: laser power: 1500 W; scanning speed: 4 mm / s; spot diameter: 3 mm; use high-purity argon as the shielding gas, and the flow rate is set at 15 L / min.

[0036] Example 2

[0037] This application provides a method for laser deposition repair of the titanium alloy surface, and the method includes:

[0038] S201: Weigh high-purity Fe, Co, Cr, C, and B powders according to the mass percentages of 20% Co powder, 6% Cr powder, 2% C powder, 11% B powder, and 61% Fe powder respectively. Add the weighed high-purity metal powders into a ball mill and dry mill for 2 h to control the particle size of the mixed powder within 150 mesh.

[0039] S202: Use 200# SiC sandpaper to polish the surface of the titanium alloy substrate until it is flat to remove impurities on the substrate surface. After polishing, clean it with acetone. After the acetone cleaning is completed and the surface of the titanium alloy substrate is dry, mix the mixed powder with absolute ethanol and evenly spread it on the polished titanium alloy substrate surface, and the spreading thickness is 0.5 mm.

[0040] S203: Place the titanium alloy substrate with the mixed powder evenly spread on its surface into a vacuum drying furnace and dry it at 120°C for 1 h. After drying, place the titanium alloy substrate on the workbench for laser deposition to obtain a deposited repair layer. Among them, the conditions for laser deposition are: laser power: 1100 W; scanning speed: 2 mm / s; spot diameter: 2 mm; use high-purity argon as the shielding gas, and the flow rate is set at 10 L / min.

[0041] Example 3

[0042] This application provides a method for laser deposition repair of the titanium alloy surface, and the method includes:

[0043] S301: Weigh high-purity Fe, Co, Cr, C, and B powders according to the mass percentages of 25% Co powder, 8% Cr powder, 3% C powder, 12% B powder, and 52% Fe powder respectively. Add the weighed high-purity metal powders into a ball mill and dry mill for 3 h to control the particle size of the mixed powder within 200 mesh.

[0044] S302: Polish the surface of the titanium alloy substrate with 200# SiC sandpaper until it is flat to remove impurities on the substrate surface. After polishing, clean it with acetone. After the acetone cleaning is completed and the surface of the titanium alloy substrate is dry, mix the mixed powder with absolute ethanol and spread it evenly on the polished titanium alloy substrate surface, with a spreading thickness of 0.8 mm.

[0045] S303: Put the titanium alloy substrate with the mixed powder evenly spread on its surface into a vacuum drying oven and dry it at a temperature of 150 °C for 2 h. After drying, place the titanium alloy substrate on the workbench for laser deposition to obtain a deposited repair layer. Among them, the conditions for laser deposition are: laser power: 2000 W; scanning speed: 6 mm / s; spot diameter: 5 mm; use high-purity argon as the shielding gas, and the flow rate is set at 20 L / min.

[0046] Example 4

[0047] This application provides a method for laser deposition repair of the titanium alloy surface, and this method includes:

[0048] S401: Weigh high-purity Fe, Co, Cr, C, and B powders according to the mass percentages of 20% Co powder, 4% Cr powder, 4% C powder, 8% B powder, and 64% Fe powder respectively. Add the weighed high-purity metal powders to a ball mill for dry grinding for 3 h to control the particle size of the mixed powder within 250 mesh.

[0049] S402: Polish the surface of the titanium alloy substrate with 200# SiC sandpaper until it is flat to remove impurities on the substrate surface. After polishing, clean it with acetone. After the acetone cleaning is completed and the surface of the titanium alloy substrate is dry, mix the mixed powder with absolute ethanol and spread it evenly on the polished titanium alloy substrate surface, with a spreading thickness of 0.8 mm.

[0050] S403: Put the titanium alloy substrate with the mixed powder evenly spread on its surface into a vacuum drying oven and dry it at a temperature of 140 °C for 1 h. After drying, place the titanium alloy substrate on the workbench for laser deposition to obtain a deposited repair layer. Among them, the conditions for laser deposition are: laser power: 1600 W; scanning speed: 5 mm / s; spot diameter: 3 mm; use high-purity argon as the shielding gas, and the flow rate is set at 12 L / min.

[0051] This application also conducts XRD detection, SEM detection, and friction coefficient detection on the deposited repair layers in Example 1 respectively to obtain the appendix Figures 1-4 .

[0052] According to the appendix Figure 1 It can be seen that a TiB2 ceramic phase is formed in the deposited repair layer, which indicates that the Fe-Co-Cr-C-B mixed powder in-situ deposits on the titanium alloy surface to form large-grained TiB2 ceramic phases.

[0053] According to the attached Figure 2 、 3 it can be seen that the surface of the deposited repair layer is relatively smooth, the large-grained TiB2 ceramic phase is uniformly distributed in the deposited repair layer, and there are no defects such as cracks and pores. The granular TiB2 can make the deposited repair layer have a smooth surface, is not prone to stress concentration, tends to have no cracks, and thus the deposited repair layer is not prone to cracking under extreme working conditions such as high temperature, high pressure, and heavy load.

[0054] According to the attached Figure 4 it can be seen that the average friction coefficient of the deposited repair layer is 0.41, which indicates that the deposited repair layer has a small friction coefficient.

[0055] The above are only the preferred embodiments of the present application and are not used to limit the present application. For those skilled in the art, various changes and modifications can be made to the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A titanium alloy surface laser deposition repair method, characterized in that: include: Put high-purity Fe, Co, Cr, C, and B powders into a ball mill and dry grind for 2-4 hours to obtain a mixed powder with a particle size of 150-300 mesh; wherein the mass percentages of the Fe, Co, Cr, C, and B powders are: 15-25% Co powder, 4-8% Cr powder, 1-4% C powder, 8-12% B powder, and the rest is pure Fe powder; The mixed powder is mixed with anhydrous ethanol and spread on the polished titanium alloy substrate surface by 0.5-1 mm; After the titanium alloy substrate is dried at a temperature of 120-150°C for 1-2 hours, laser deposition is performed to form a smooth deposition repair layer on the surface of the titanium alloy substrate; wherein, during the laser deposition process, high-purity B powder and the Ti element on the surface of the titanium alloy substrate in situ generate a TiB2 ceramic phase; the average microhardness of the deposition repair layer is 1300-1600HV, and the average friction coefficient is 0.35-0.

52.

2. The titanium alloy surface laser deposition repair method according to claim 1, characterized in that: The mass percentages of the Fe, Co, Cr, C and B powders are: 15% Co powder, 5% Cr powder, 1% C powder, 10% B powder and 69% iron powder.

3. The titanium alloy surface laser deposition repair method according to claim 1, characterized in that: The conditions of the laser deposition are: laser power: 1100-2000W; scanning speed: 2-6mm / s; spot diameter: 2-5mm; high-purity argon is used as the protective gas, and the flow rate is set at 10-20L / min.

4. The titanium alloy surface laser deposition repair method according to claim 1, characterized in that: The conditions of the laser deposition are: laser power: 1500 W; scanning speed: 4 mm / s; spot diameter: 3 mm; high-purity argon gas is used as the protective gas, and the flow rate is set at 15 L / min.

5. The titanium alloy surface laser deposition repair method according to claim 1, characterized in that: The particle size of the mixed powder is 300 meshes.

6. The titanium alloy surface laser deposition repair method according to claim 1, characterized in that: The drying temperature of the mixed powder and the titanium alloy matrix is ​​140° C., and the drying time is 1.5 hours.

7. A titanium alloy surface laser deposition repair layer, characterized in that: The repairing method is prepared by any one of claims 1 to 6.

Images