Polishing method for inner runner of high-strength aluminum alloy for additive manufacturing

Abstract

The invention provides a polishing method for an inner runner of a high-strength aluminum alloy for additive manufacturing, and belongs to the field of metal surface treatment. The method comprises the following steps: mixing an abrasive with a base solution to obtain an abrasive fluid; and abrasive flow polishing is conducted on an inner flow channel of the high-strength aluminum alloy through abrasive fluid, and a polished high-strength aluminum alloy workpiece is obtained. The polishing abrasive used in the method is easy to prepare, does not pollute the environment, can be repeatedly used and is low in use cost; the invention provides a polishing method for an inner runner of a high-strength aluminum alloy for additive manufacturing by adopting an abrasive flow polishing technology, and the surface quality of a workpiece is improved by changing the proportion of an abrasive and designing the polishing pressure and time. The surface roughness of the polished inner runner of the high-strength aluminum alloy manufactured by the additive material is reduced to Ra2.630 microns from Ra10.8 microns within 15 minutes, and excellent surface quality is obtained.

Description

Technical Field

[0001] The present invention relates to the field of metal surface treatment, and in particular to a method for polishing an inner flow channel of an additively manufactured high-strength aluminum alloy. Background Art

[0002] High-strength aluminum alloys, through carefully designed alloy compositions and advanced processing techniques, form a uniform and dense microstructure, maintaining excellent structural stability across various temperature conditions, thereby ensuring reliability during use. Due to their high strength, low density, and excellent overall performance, achieved through precise control of alloying elements within the alloy system, high-strength aluminum alloys are often considered the "leaders" of the aluminum alloy family. High-strength aluminum alloys are used in the aerospace industry to manufacture critical structural components such as aircraft beams and wings. They are also used to reduce vehicle weight and increase structural strength in high-speed trains and automobiles. In the defense and military industries, they are widely used in various types of weaponry, making them an indispensable material in modern industry. Fatigue fracture is the most common failure mode of aerospace components. Because the surface of a part is the interface between the part and the external environment, many fatigue cracks originate there. Therefore, surface quality significantly affects its endurance limit and corrosion resistance. A good polishing process can reduce surface roughness, improve surface finish, and enhance surface corrosion resistance. However, currently, no ideal polishing process for high-strength aluminum alloys exists. Summary of the Invention

[0003] The purpose of the present invention is to provide a method for polishing the inner flow channel of a high-strength aluminum alloy manufactured by additive manufacturing, so as to reduce the surface roughness of the metal and improve the surface quality of the aluminum alloy.

[0004] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0005] The present invention provides a method for polishing an inner flow channel of an additively manufactured high-strength aluminum alloy, comprising the following steps:

[0006] mixing an abrasive with a base fluid to obtain an abrasive fluid;

[0007] Performing abrasive flow polishing on the inner flow channel of the high-strength aluminum alloy using the abrasive fluid to obtain a polished high-strength aluminum alloy workpiece;

[0008] The abrasives include silicon carbide abrasives of a first particle size, silicon carbide abrasives of a second particle size, and silicon carbide abrasives of a third particle size;

[0009] The base fluid includes polyethylene glycol and water.

[0010] Preferably, the particle size of the first particle size silicon carbide abrasive is 220-320 mesh, the particle size of the second particle size silicon carbide abrasive is 600-700 mesh, and the particle size of the third particle size silicon carbide abrasive is 1000-1200 mesh.

[0011] Preferably, based on the total mass of the abrasive as 100%, the mass of the first particle size silicon carbide abrasive accounts for 38-42%, the mass of the second particle size silicon carbide abrasive accounts for 35-40%, and the mass of the third particle size silicon carbide abrasive accounts for 18-27%.

[0012] Preferably, the mass ratio of the polyethylene glycol to water is 6.8-7.2:2.8-3.2.

[0013] Preferably, the mass volume ratio of the abrasive to the base liquid is 90-120 g:180-230 mL.

[0014] Preferably, the alloy matrix of the high-strength aluminum alloy includes Al-Mn-Mg-Sc-Zr alloy.

[0015] Preferably, the Al-Mn-Mg-Sc-Zr alloy includes the following components in percentage by weight: Mn 4.0-6.0wt%, Mg 1.0-2.0wt%, Sc 0.5-1.0wt%, Zr 0.1-0.6wt%, and the balance is Al.

[0016] Preferably, the polishing pressure is 4-8 MPa, and the polishing time is 13-18 min.

[0017] Preferably, after polishing, the process further comprises cleaning and vacuum drying the polished high-strength aluminum alloy workpiece; the vacuum drying temperature is 110-120° C., and the time is 12 hours.

[0018] Beneficial effects of the present invention:

[0019] The present invention adopts abrasive flow polishing technology for the inner flow channel of high-strength aluminum alloy manufactured by additive manufacturing and provides a polishing method. By changing the proportion of abrasives and designing the polishing pressure and time, the surface quality of the workpiece is improved, so that the surface roughness of the inner flow channel of the additively manufactured high-strength aluminum alloy workpiece after polishing is reduced from Ra10.8μm to Ra2.630μm within 15 minutes, thereby obtaining excellent surface quality and realizing high-speed and efficient preparation of polished metal of the inner flow channel of the high-strength aluminum alloy obtained by additive manufacturing technology.

[0020] The present invention uses three different sizes of silicon carbide abrasives to form the abrasive. The first size has large particles and strong cutting force, which is used to quickly remove macroscopic defects such as surface burrs and scales and initially level the surface. The second size has medium particles, which is used to refine the surface texture, eliminate rough grinding marks, and prepare for fine grinding. The third size has fine particles, which is mainly used for friction polishing, eliminating fine scratches and achieving a near-mirror finish. The polishing abrasive used in the present invention is simple to prepare, does not cause pollution to the environment, is reusable, and has a low cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 Schematic diagram of the abrasive flow polishing process of the present invention. DETAILED DESCRIPTION

[0022] The present invention provides a method for polishing an inner flow channel of an additively manufactured high-strength aluminum alloy, comprising the following steps:

[0023] mixing an abrasive with a base fluid to obtain an abrasive fluid;

[0024] Performing abrasive flow polishing on the inner flow channel of the high-strength aluminum alloy using the abrasive fluid to obtain a polished high-strength aluminum alloy workpiece;

[0025] The abrasives include silicon carbide abrasives of a first particle size, silicon carbide abrasives of a second particle size, and silicon carbide abrasives of a third particle size;

[0026] The base fluid includes polyethylene glycol and water.

[0027] In the present invention, unless otherwise specified, the raw materials required for preparation are all commercially available products well known to those skilled in the art.

[0028] The present invention preferably prepares abrasives of different particle sizes, mixes the abrasives with a base liquid, turns on a stirring device, and continuously stirs until an abrasive fluid with uniform texture and excellent fluidity is formed; and injects the abrasive fluid into an abrasive storage tank of a high-speed jet abrasive flow polishing device to ensure good sealing.

[0029] In the present invention, the abrasive is preferably a first-size silicon carbide abrasive, a second-size silicon carbide abrasive, and a third-size silicon carbide abrasive.

[0030] In the present invention, the particle size of the first particle size silicon carbide abrasive is preferably 220-320 mesh, more preferably 320 mesh; the particle size of the second particle size silicon carbide abrasive is preferably 600-700 mesh, more preferably 600 mesh; the particle size of the third particle size silicon carbide abrasive is preferably 1000-1200 mesh, more preferably 1000 mesh.

[0031] In the present invention, based on the total mass of the abrasive as 100%, the mass proportion of the first particle size silicon carbide abrasive is preferably 38-42%, and more preferably 40%; the mass proportion of the second particle size silicon carbide abrasive is preferably 35-40%, and more preferably 35%; the mass proportion of the third particle size silicon carbide abrasive is 18-27%, and more preferably 25%.

[0032] In the present invention, the base liquid preferably includes polyethylene glycol and water, and the mass ratio of polyethylene glycol to water is preferably 6.8-7.2:2.8-3.2, and more preferably 7:3; polyethylene glycol has good lubricity and dispersibility, can reduce abrasive impact damage, inhibit frictional heat accumulation, and prevent abrasive agglomeration and sedimentation, and polyethylene glycol is degradable, easy to clean, and suitable for multi-size abrasives.

[0033] In the present invention, the mass volume ratio of the abrasive to the base liquid is preferably 90-120 g:180-230 mL, and more preferably 100 g:200 mL.

[0034] The present invention has no particular limitation on the stirring speed and time when the abrasive and the base liquid are mixed, as long as the abrasive fluid is free of agglomeration, stratification or obvious precipitation when observed with the naked eye.

[0035] The present invention preferably utilizes the abrasive fluid to perform abrasive flow polishing on the inner flow channel of the high-strength aluminum alloy to obtain a polished high-strength aluminum alloy workpiece; specifically: utilizing ultrasonic cleaning equipment to perform all-around cleaning of the high-strength aluminum alloy workpiece, the ultrasonic cleaning equipment used in the present invention is the JIEMENG JP-12000D ultrasonic cleaning machine, the present invention has no special restrictions on the cleaning power and time of the ultrasonic cleaning machine, and can be adjusted according to the condition of the workpiece to thoroughly remove oil stains, impurities and processing residues on the surface of the workpiece; the cleaned high-strength aluminum alloy workpiece is clamped on the fixture of the high-speed jet abrasive flow polishing equipment, the high-speed jet abrasive flow polishing equipment is turned on, the parameter setting interface is entered, and the polishing pressure and polishing time are set; during the entire polishing process, as Figure 1 As shown in the figure, under the strong drive of the polishing pressure setting value, the abrasive fluid acts as an abrasive medium in the form of a high-speed jet and continuously flows through the inner flow channel of the high-strength aluminum alloy workpiece; a dedicated person is arranged to monitor the equipment operation status and the flow status of the abrasive fluid in real time, and the sensors, observation windows and monitoring software provided by the equipment are used to ensure that various parameters remain stable at all times, ensuring that the abrasive can fully and evenly polish all parts of the workpiece inner flow channel to avoid polishing dead corners.

[0036] In the present invention, the high-strength aluminum alloy is obtained by additive manufacturing of Al-Mn-Mg-Sc-Zr alloy. The additive manufacturing method is preferably laser powder bed melting. The technical parameters of the laser powder bed melting are preferably: laser power 400W, scanning speed 100mm / s, scanning spacing 100μm, and printing layer thickness 30μm.

[0037] The present invention has no special limitation on the source of the Al-Mn-Mg-Sc-Zr alloy. The Al-Mn-Mg-Sc-Zr alloy described in the embodiment is preferably provided by Suzhou Beifeng Technology Co., Ltd.

[0038] In the present invention, the Al-Mn-Mg-Sc-Zr alloy preferably includes the following components in percentage by weight: Mn 4.0-6.0wt%, Mg 1.0-2.0wt%, Sc 0.5-1.0wt%, Zr 0.1-0.6wt%, and the balance is Al. The chemical composition of the alloy matrix Al-Mn-Mg-Sc-Zr used in the embodiment is preferably Al-4.88Mn-1.66Mg-0.69Sc-0.33Zr.

[0039] In the present invention, the polishing pressure is preferably 4 to 8 MPa, more preferably 6 MPa, and the polishing time is preferably 13 to 18 minutes, more preferably 15 minutes.

[0040] After polishing is completed, the present invention preferably takes out the high-strength aluminum alloy workpiece and rinses it thoroughly with high-pressure clean water to ensure that the silicon carbide abrasive particles remaining on the workpiece surface and in the inner flow channel can be completely removed; the cleaned high-strength aluminum alloy workpiece is placed in a vacuum drying device for vacuum drying to finally obtain a polished high-strength aluminum alloy workpiece.

[0041] In the present invention, the vacuum drying temperature is preferably 110 to 120° C., more preferably 115 to 120° C., and the drying time is preferably 12 hours.

[0042] The technical solutions provided by the present invention are described in detail below with reference to the embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0043] The ultrasonic cleaning equipment used in Examples 1 to 5 and Comparative Examples 1 to 3 was a JIEMENG JP-12000D ultrasonic cleaning machine;

[0044] The high-strength aluminum alloys used in Examples 1 to 5 and Comparative Examples 1 to 3 were all obtained by additive manufacturing of Al-Mn-Mg-Sc-Zr alloy; the Al-Mn-Mg-Sc-Zr alloy used was provided by Suzhou Beifeng Technology Co., Ltd., and its chemical composition was Al-4.88Mn-1.66Mg-0.69Sc-0.33Zr; the additive manufacturing method was laser powder bed melting, and the technical parameters were: laser power 400W, scanning speed 100mm / s, scanning spacing 100μm, and print layer thickness 30μm; the printed high-strength aluminum alloy contained an internal flow channel.

[0045] Example 1

[0046] like Figure 1 As shown, 40% by mass of 320-mesh silicon carbide abrasive, 35% by mass of 600-mesh silicon carbide abrasive, and 25% by mass of 1000-mesh silicon carbide abrasive were mixed evenly, and then added to a base liquid obtained by mixing polyethylene glycol and water in a mass ratio of 7:3. The volume ratio of the total mass of the abrasive to the base liquid was 100 g:200 mL. The stirring device was turned on and the stirring was continued to form an abrasive fluid, which was injected into the abrasive storage tank of the high-speed jet abrasive flow polishing equipment as an abrasive medium.

[0047] The high-strength aluminum alloy workpiece to be polished was cleaned using an ultrasonic cleaning device, and the cleaned workpiece was clamped on the fixture of a high-speed jet abrasive flow polishing device. The inner flow channel of the Al-Mn-Mg-Sc-Zr alloy workpiece was abrasively polished using an abrasive fluid at a polishing pressure of 6 MPa and a polishing time of 15 minutes.

[0048] After polishing is completed, the high-strength aluminum alloy workpiece is taken out and fully rinsed with high-pressure water. Then, it is placed in a vacuum drying equipment and vacuum dried at 120°C for 12 hours until the workpiece is completely dry to obtain a polished high-strength aluminum alloy workpiece.

[0049] Example 2

[0050] The only difference from Example 1 is:

[0051] Polishing pressure is 4MPa;

[0052] A polished high-strength aluminum alloy workpiece is obtained.

[0053] Example 3

[0054] The only difference from Example 1 is:

[0055] Polishing pressure is 8MPa;

[0056] A polished high-strength aluminum alloy workpiece is obtained.

[0057] Example 4

[0058] The only difference from Example 1 is:

[0059] Polishing time is 13min;

[0060] A polished high-strength aluminum alloy workpiece is obtained.

[0061] Example 5

[0062] The only difference from Example 1 is:

[0063] Polishing time is 18 minutes;

[0064] A polished high-strength aluminum alloy workpiece is obtained.

[0065] Comparative Example 1

[0066] The only difference from Example 1 is:

[0067] Polishing pressure is 2MPa;

[0068] A polished high-strength aluminum alloy workpiece is obtained.

[0069] Comparative Example 2

[0070] The only difference from Example 1 is:

[0071] The polishing pressure is 10MPa;

[0072] A polished high-strength aluminum alloy workpiece is obtained.

[0073] Comparative Example 3

[0074] The only difference from Example 1 is:

[0075] Polishing time is 20min;

[0076] A polished high-strength aluminum alloy workpiece is obtained.

[0077] Performance Testing

[0078] The surface roughness of the inner flow channels of the high-strength aluminum alloy before polishing, the high-strength aluminum alloy obtained in Examples 1 to 5, and the high-strength aluminum alloy after polishing obtained in Comparative Examples 1 to 3 were tested according to GB / T 1031-2009 "Product Geometric Technical Specification (GPS) Surface Structure Profile Method Surface Roughness Parameters and Their Values". The results are shown in Table 1.

[0079] Table 1 Surface roughness of the inner flow channel of the high-strength aluminum alloy before polishing, and the high-strength aluminum alloys of Examples 1 to 5 and Comparative Examples 1 to 3 after polishing

[0080] Serial number Surface roughness / (μm) Al-Mn-Mg-Sc-Zr alloy before polishing 10.8 Example 1 2.630 Example 2 2.705 Example 3 3.218 Example 4 2.812 Example 5 3.045 Comparative Example 1 3.117 Comparative Example 2 4.102 Comparative Example 3 4.527

[0081] As can be seen from Table 1, by comparing the surface roughness of the inner flow channel of the high-strength aluminum alloy in Examples 1 to 3 and Comparative Examples 1 to 2 before and after polishing, it can be found that compared with Comparative Examples 1 to 2, the inner flow channel of the high-strength aluminum alloy prepared in Examples 1 to 3 after polishing is significantly reduced compared with that before polishing, among which Example 1 has the best effect, indicating that when the polishing pressure is 4 to 8 MPa, a better polishing effect can be achieved, and the polishing effect is best when the polishing pressure is 6 MPa; comparing the surface roughness before and after polishing of Example 1, Examples 4 to 5 and Comparative Example 3, it can be found that compared with Comparative Example 3, the inner flow channel of the high-strength aluminum alloy prepared in Examples 1 and 4 to 5 after polishing is also significantly reduced compared with that before polishing, among which Example 1 has the best effect, indicating that when the polishing pressure is 6 MPa, a better polishing effect can be achieved by setting the polishing time to 13 to 18 min, and the polishing effect is best when the polishing pressure is 15 min. The surface roughness of the inner flow channel of the workpiece can reach as low as Ra2.630 μm, which is significantly reduced compared with that before polishing.

[0082] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for polishing the inner flow channel of an additively manufactured high-strength aluminum alloy, characterized in that: The following steps are involved: mixing an abrasive with a base fluid to obtain an abrasive fluid; Performing abrasive flow polishing on the inner flow channel of the high-strength aluminum alloy using the abrasive fluid to obtain a polished high-strength aluminum alloy workpiece; The abrasives include silicon carbide abrasives of a first particle size, silicon carbide abrasives of a second particle size, and silicon carbide abrasives of a third particle size; The base fluid includes polyethylene glycol and water.

2. The polishing method according to claim 1, wherein The particle size of the first particle size silicon carbide abrasive is 220-320 meshes, the particle size of the second particle size silicon carbide abrasive is 600-700 meshes, and the particle size of the third particle size silicon carbide abrasive is 1000-1200 meshes.

3. The polishing method according to claim 2, wherein: Taking the total mass of the abrasive as 100%, the mass of the first particle size silicon carbide abrasive accounts for 38-42%, the mass of the second particle size silicon carbide abrasive accounts for 35-40%, and the mass of the third particle size silicon carbide abrasive accounts for 18-27%.

4. The polishing method according to claim 1, wherein The mass ratio of the polyethylene glycol to water is 6.8-7.2:2.8-3.

2.

5. The polishing method according to claim 1, wherein The mass volume ratio of the abrasive to the base liquid is 90-120 g:180-230 mL.

6. The polishing method according to claim 1, wherein The alloy matrix of the high-strength aluminum alloy includes Al-Mn-Mg-Sc-Zr alloy.

7. The polishing method according to claim 6, characterized in that The Al-Mn-Mg-Sc-Zr alloy includes the following components in percentage by weight: Mn 4.0-6.0wt%, Mg 1.0-2.0wt%, Sc 0.5-1.0wt%, Zr 0.1-0.6wt%, and the balance is Al.

8. The polishing method according to claim 1, wherein The polishing pressure is 4-8 MPa, and the polishing time is 13-18 minutes.

9. The polishing method according to claim 1, wherein: After polishing, the high-strength aluminum alloy workpiece is cleaned and vacuum-dried in sequence; the vacuum drying temperature is 110-120° C. and the time is 12 hours.

Images