Aluminum-tin alloy-steel bimetallic composite and method of making same

Abstract

The application discloses an aluminum-tin alloy-steel bimetal composite material and a manufacturing method thereof, and comprises the following steps: sintering copper powder on the surface of a steel strip which needs to be compounded with aluminum-tin alloy; laying aluminum-tin alloy powder on the surface of the steel strip with the sintered copper powder; rolling the steel strip with the laid aluminum-tin alloy powder to compound the aluminum-tin alloy powder on the steel strip, so as to form a bimetal composite steel strip; placing the bimetal composite steel strip in a sintering furnace for sintering; rolling the sintered bimetal composite steel strip into a final size; and performing annealing treatment on the bimetal composite steel strip after the second rolling. The aluminum-tin bearing alloy is used as a working layer, and high-quality low-carbon steel with certain strength and toughness is used as a base layer, so that the bimetal composite material has good fatigue resistance, compatibility, compliance and embedding property. The aluminum-tin alloy layer of the bimetal composite material is uniform, the material has excellent fatigue resistance, the preparation method has the characteristics of simple process, low cost and high production efficiency.

Description

Technical Field

[0001] This invention relates to an aluminum-tin alloy-steel bimetallic composite material and its manufacturing method, belonging to the technical field of sliding bearing materials and their preparation. Background Technology

[0002] Traditional aluminum-tin alloy-steel bimetallic composite materials are generally produced by rolling cast aluminum-tin alloy into plates, which are then rolled together with surface-treated steel plates. Alternatively, to improve the bonding strength between the aluminum-tin alloy and the steel matrix, a layer of pure aluminum is typically rolled between the aluminum-tin alloy and the steel plate. For example, CN102935447A discloses an aluminum-tin-steel metal bearing material and its manufacturing method, in which an aluminum-tin alloy ingot is first double-sided composite rolled with pure aluminum, with a double-sided composite rolling rate of ≥50%. Then, the double-sided composite aluminum-tin alloy plate is rolled together with a roughened steel plate in a single pass, with a rolling rate of ≥47%. The composite material is then annealed before use. However, cast aluminum-tin alloy ingots are prone to severe tin phase segregation due to the immiscibility of tin and aluminum at room temperature and the significant density difference between them, resulting in varying degrees of weakening of the final alloy's tribological properties. Furthermore, this method requires two composite rolling processes and a high rolling rate to complete the composite process, placing high demands on equipment and resulting in higher production line investment and costs. Additionally, this process is prone to delamination and bubble defects between the aluminum-tin alloy layer and the steel substrate, leading to poor bonding and low product yield. Summary of the Invention

[0003] The purpose of this invention is to provide an aluminum-tin alloy-steel bimetallic composite material and its preparation method. The prepared composite material has a uniform aluminum-tin alloy layer structure and excellent fatigue performance. The preparation method is characterized by simple process, low cost and high production efficiency.

[0004] To solve the above-mentioned technical problems, the objective of this invention is achieved as follows:

[0005] The present invention relates to an aluminum-tin alloy-steel bimetallic composite material, comprising a steel substrate, a copper plating layer, and an aluminum-tin alloy layer;

[0006] The copper plating layer has copper particles distributed on it; the aluminum-tin alloy layer is an aluminum alloy with tin particles evenly distributed on it; the copper particles are bonded to the copper plating layer by sintering copper powder; the aluminum-tin alloy layer is formed by rolling and sintering aluminum-tin alloy powder.

[0007] The copper powder has a particle size of 50-250 mesh.

[0008] Based on the above scheme and as a preferred embodiment of the above scheme: the steel substrate is carbon steel with a thickness of 0.5-5mm; the copper plating layer has a thickness of 1-10μm; and the aluminum-tin alloy layer has a thickness of 0.1-0.6mm.

[0009] Based on the above scheme and as a preferred embodiment of the above scheme: the particle size of the copper powder is 80-180 mesh.

[0010] Based on the above scheme and as a preferred embodiment of the above scheme: the aluminum-tin alloy layer is an AlSn20Cu or AlSn12SiCu alloy.

[0011] This invention also relates to a method for manufacturing an aluminum-tin alloy-steel bimetallic composite material, comprising the following steps:

[0012] S1. Sintered copper powder: Copper powder is sintered on the surface of the steel strip that requires composite aluminum-tin alloy; the sintering amount of copper powder is 200-500 grams per square meter; the steel strip needs to be degreased, derusted and copper-plated before sintering the copper powder;

[0013] S2. Laying aluminum-tin alloy powder: Laying aluminum-tin alloy powder on the surface of the steel strip sintered with copper powder; the thickness of the aluminum-tin alloy powder is 0.3-2.0 mm;

[0014] S3. First rolling: The steel strip with aluminum-tin alloy powder is rolled through a rolling mill to roll the aluminum-tin alloy powder onto the steel strip, forming a bimetallic composite steel strip; during the rolling process, the rolling deformation of the steel strip is 3-25%;

[0015] S4. Sintering: The bimetallic composite steel strip is placed in a sintering furnace for sintering at a temperature of 300-500℃. The atmosphere of the sintering furnace is air, nitrogen or argon.

[0016] S5. Second rolling: The sintered bimetallic composite steel strip is rolled into its final size by a rolling mill, with a rolling deformation of more than 10%.

[0017] S6. Annealing: The bimetallic composite steel strip after the second rolling is placed in an annealing furnace for annealing treatment. The annealing temperature is 300-500℃ and the annealing time is 0.5-5 hours.

[0018] Based on the above scheme and as a preferred option, the sintering amount of copper powder in step S1 is 300-400 grams per square meter.

[0019] Based on the above scheme and as a preferred option: the particle size of the aluminum-tin alloy powder in step S2 is between 80 and 200 mesh.

[0020] Based on the above scheme and as a preferred option, the rolling deformation of the steel strip in step S3 is 5%-15%.

[0021] Based on the above scheme and as a preferred option, the sintering temperature of the rolled bimetallic composite steel strip in step S4 is 380-480℃, and the sintering time is 0.5 hours to 1 hour.

[0022] Based on the above scheme and as a preferred option: the deformation amount of the second rolling in step S5 is >30%; the annealing temperature of the composite material in step S6 is 350℃-450℃, the annealing time is 1 hour-2 hours, and it is air-cooled after annealing.

[0023] The beneficial effects of this invention are as follows: The aluminum-tin alloy-steel bimetallic composite material and its preparation method involved in this invention use an aluminum-tin bearing alloy as the working layer and high-quality low-carbon steel with certain strength and toughness as the base layer, exhibiting good fatigue strength, compatibility, compliance, and embedding properties. The aluminum-tin alloy layer of this bimetallic composite material has a uniform microstructure, excellent fatigue resistance, and its preparation method is characterized by simple process, low cost, and high production efficiency. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the structure of the aluminum-tin alloy-steel bimetallic composite material involved in this invention;

[0025] Figure 2 This is a schematic diagram of the process flow of the preparation method involved in this invention;

[0026] Figure 3 This is a metallographic photograph of the aluminum-tin alloy layer in an aluminum-tin alloy-steel bimetallic composite material.

[0027] The markings in the diagram are explained as follows: 1. Steel substrate; 2. Copper plating layer; 3. Copper particles; 4. Aluminum alloy; 5. Tin particles; 6. Steel strip; 7. Adhesive roller brush; 8. Copper powder hopper; 9. Sintering furnace one; 10. Cooling section; 11. Aluminum-tin alloy hopper; 12. Rolling mill one; 13. Sintering furnace two; 14. Rolling mill two; 15. Aluminum-tin alloy-steel composite strip; 16. Annealing furnace; 17. Aluminum alloy substrate; 18. Tin. Detailed Implementation

[0028] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0029] Combination Figure 1 , Figure 2 and Figure 3 The present invention will be described in detail below. The present invention relates to an aluminum-tin alloy-steel bimetallic composite material, comprising a steel substrate 1, a copper-plated layer 2, and an aluminum-tin alloy layer.

[0030] The copper plating layer 2 has copper particles 3 distributed on it; the aluminum-tin alloy layer is an aluminum alloy 4 with tin particles 5 evenly distributed on it; the copper particles 3 are bonded to the surface of the copper plating layer 2 by sintering copper powder; the aluminum-tin alloy layer is formed by rolling and sintering aluminum-tin alloy powder.

[0031] Furthermore, the steel substrate is carbon steel with a thickness of 0.5-5mm, and is subjected to copper plating treatment on its surface; the copper powder is commercially available conventional tin bronze spherical powder, which is bonded to the copper plating layer by sintering, and its particle size is between 50 mesh and 250 mesh; the aluminum-tin bearing alloy layer is formed by rolling and sintering aluminum-tin alloy powder, and the alloy layer thickness is 0.1-0.6mm.

[0032] Through rolling, the surface of the matrix with sintered copper particles 3 can form a strong mechanical bond with the aluminum-tin alloy powder, ensuring that the composite material will not delaminate or detach during subsequent processing. Copper powder particles that are too large or too small are detrimental to subsequent rolling composite processes, reducing the bonding strength and making delamination or detachment more likely during rolling. Preferably, the copper powder particle size is 80-180 mesh.

[0033] The copper plating layer 2 on the steel substrate 1 improves the bonding strength between the copper particles 3 and the steel substrate 1, thereby enhancing the anti-detachment and fatigue resistance of the aluminum-tin alloy layer. Furthermore, the copper plating layer also improves the bonding strength between the aluminum-tin alloy and the steel substrate. If the copper plating layer is less than 1 μm thick, it cannot effectively achieve the above-mentioned effects; however, if the copper plating layer is too thick, it will increase material costs. Preferably, the thickness of the copper plating layer on the steel substrate is 2-5 μm.

[0034] Furthermore, the aluminum-tin alloy used in the aluminum-tin alloy layer can be a conventional aluminum-based bearing alloy composition such as AlSn20Cu or AlSn12SiCu, prepared by atomization powder preparation. Due to its extremely high cooling rate, the atomization method prevents tin segregation in the resulting aluminum-tin alloy powder, resulting in a very uniform and fine distribution, thus enabling the final alloy to achieve ideal surface friction properties.

[0035] The present invention relates to a method for manufacturing an aluminum-tin alloy-steel bimetallic composite material, comprising the following steps:

[0036] S1. Sintering copper powder: Copper powder is sintered on the surface of the steel strip 6 where the aluminum-tin alloy composite is required; the sintering amount of copper powder is 200-500 grams per square meter; the steel strip needs to be degreased, derusted, and copper-plated before sintering the copper powder, forming a copper plating layer 2. The steel strip 6 used in this step is the steel matrix 1 in the prepared aluminum-tin alloy-steel bimetallic composite material.

[0037] Furthermore, the sintering amount of copper powder is 300-400 grams per square meter. After sintering, the copper powder forms copper particles 3 that adhere to the surface of the copper plating layer 2.

[0038] S2. Laying aluminum-tin alloy powder: Laying aluminum-tin alloy powder on the surface of the steel strip sintered with copper powder; the thickness of the aluminum-tin alloy powder is 0.3-2.0 mm. The particle size of the aluminum-tin alloy powder used is between 80-200 mesh.

[0039] S3. First Rolling: The steel strip coated with aluminum-tin alloy powder is rolled through a rolling mill to bond the aluminum-tin alloy powder onto the steel strip, forming a bimetallic composite steel strip. During the rolling process, the rolling deformation of the steel strip is 3-25%. A deformation of less than 3% will prevent the alloy powder from adhering firmly to the steel strip, while a deformation of more than 25% will cause rolling cracks in the alloy layer. Further, the rolling deformation of the steel strip can be selected as 5%-15%.

[0040] S4. Sintering: The bimetallic composite steel strip is placed in a sintering furnace for sintering at a temperature of 300-500℃. The furnace atmosphere is air, nitrogen, or argon. Sintering temperatures below 300℃ are insufficient to allow for adequate metallurgical bonding between the aluminum-tin alloy powders and are detrimental to increasing the density of the aluminum-tin alloy powder layer. Sintering temperatures above 500℃ cause excessive formation of brittle phases between the aluminum-tin alloy layer and the steel matrix, resulting in reduced interlayer bonding strength. Furthermore, the sintering temperature of the rolled bimetallic composite steel strip is 380-480℃, and the sintering time is 0.5-1 hour.

[0041] S5. Second Rolling: The sintered bimetallic composite steel strip is rolled to its final dimensions using a rolling mill, with a rolling deformation of more than 10%. The greater the rolling deformation in this step, the stronger the bond between the aluminum-tin alloy layer and the steel substrate. A rolling deformation of less than 10% is detrimental to increasing the density of the alloy layer and also hinders the improvement of its plasticity through subsequent recrystallization heat treatment. Furthermore, the deformation in the second rolling is >30%.

[0042] S6. Annealing: The bimetallic composite steel strip after the second rolling is placed in an annealing furnace for annealing treatment. The annealing temperature is 300-500℃, and the annealing time is 0.5-5 hours. Further, in step S6, the composite material is annealed at 350℃-450℃ for 1-2 hours, followed by air cooling. This step can remove the internal stress of the aluminum-tin alloy-steel bimetallic composite material, allowing the aluminum-tin alloy layer to recrystallize, improving the plasticity of the alloy layer material, and further increasing the bonding strength between the alloy layer and the steel matrix. Generally, choosing a lower annealing temperature and a shorter time may result in incomplete annealing, failing to completely eliminate the internal stress of the bimetallic composite material, and resulting in lower plasticity. If a higher annealing temperature and a longer time are chosen, it will lead to an increase in the brittle phase in the bonding layer, reducing the bonding force between the alloy layer and the steel strip.

[0043] Example

[0044] The manufacturing method of an aluminum-tin bearing alloy-steel bimetallic composite material involved in this embodiment includes the following steps:

[0045] S1. Commercially available ST12 cold-rolled steel strip, 2mm thick and 300mm wide, is selected. The strip is degreased, derusted, and copper-plated to a thickness of 2μm. The strip is uncoiled, and a layer of adhesive is applied to its surface using a liquid adhesive roller. The strip then passes through a copper powder hopper, where -120 mesh +160 mesh copper powder is evenly sprinkled onto its surface. The hopper flow rate is controlled to ensure approximately 320 grams of copper powder per square meter of strip. The copper-powder-coated strip enters a continuous sintering furnace at 930℃ for 20 minutes, after which it is cooled in a cooling zone.

[0046] S2. The steel strip with sintered copper powder passes through the aluminum-tin alloy powder hopper. The composition of the aluminum-tin alloy powder is Sn: 20%, Cu: 1%, Al: balance. The mesh size of the alloy powder is -80 to +120 mesh, and the thickness of the alloy powder layer is 1 mm.

[0047] S3. The steel strip with aluminum-tin alloy powder is rolled by a rolling mill. The rolling deformation of the steel strip is 5%. The aluminum-tin alloy powder is firmly bonded to the steel strip through rolling.

[0048] S4. The steel strip coated with aluminum-tin alloy powder enters the sintering furnace at a sintering temperature of 450°C for 60 minutes. The atmosphere in the sintering furnace is air.

[0049] S5. The sintered bimetallic composite steel strip is rolled to a final thickness of 2mm with a rolling deformation of 20%, and then rolled into a coil.

[0050] S6. The bimetallic alloy coil is placed in an annealing furnace for annealing at 350℃ for 2 hours. This yields an aluminum-tin alloy-steel bimetallic composite material with bearing alloy composition AlSn20Cu.

[0051] The aluminum-tin alloy-steel bimetallic composite material prepared in this embodiment, after metallographic analysis according to GB / T13298-2015 "Metallic Microstructure Examination Methods", shows that the tin distribution in the aluminum-tin alloy layer is relatively uniform. Figure 3 As shown. Because the tin is evenly distributed in the aluminum-tin alloy layer, without any clumps or flakes, the bearings made with it can lubricate the surface before an oil film forms due to the softness of the tin, preventing the bearing from seizing during startup. If the tin distribution is uneven, uneven friction will occur on the bearing surface, with higher friction in areas without tin. Since an oil film has not yet formed when the bearing starts rotating, this can cause the bearing to seize.

[0052] The aluminum-tin alloy-steel bimetallic composite material prepared in this embodiment has excellent fatigue resistance. The fatigue strength of the aluminum-tin alloy-steel bimetallic composite material obtained in this embodiment and a commercially available aluminum-tin alloy-steel bimetallic composite material with the same aluminum-tin alloy composition (AlSn20Cu) were tested under the same conditions.

[0053] The fatigue strength test process for two aluminum-tin alloy-steel bimetallic composite materials is as follows: After the test bearing made of the bimetallic composite material is installed on the sapphire bearing fatigue testing machine, it is run under no-load for 30 minutes. The load is started from 70 MPa. After running for 20 hours, the bearing is checked for any visible fatigue damage. If there is no damage, the load is increased by one level (5 MPa) and the test is continued. This process is repeated until the test bearing fails due to fatigue. The bearing load at which the bearing fails due to fatigue is the fatigue strength of the material sample on the sapphire bearing fatigue testing machine.

[0054] Tests showed that the fatigue strength of commercially available AlSn20Cu aluminum-tin alloy-steel bimetallic composite material produced by conventional methods was 90 MPa, while the fatigue strength of the AlSn20Cu aluminum-tin alloy-steel bimetallic composite material obtained by the embodiments described in the invention was 110 MPa, which is significantly better than that of commercially available materials.

[0055] The preferred embodiments of the present invention have been described in detail above. It should be understood that those skilled in the art can make numerous modifications and variations based on the concept of the present invention without creative effort. Therefore, all technical solutions that can be obtained by those skilled in the art based on the concept of the present invention through logical analysis, reasoning, or limited experimentation on the basis of existing technology should be within the scope of protection defined by the claims.

Claims

1. A method for manufacturing an aluminum-tin alloy-steel bimetallic composite material, characterized in that, it comprises a steel base, a copper plating layer and an aluminum-tin alloy layer; the copper plating layer is distributed with copper particles; the aluminum-tin alloy layer is an aluminum alloy uniformly distributed with tin particles; the copper particles are bonded on the copper plating layer by copper powder sintering; the aluminum-tin alloy layer is rolled and sintered from aluminum-tin alloy powder; the particle size of the copper powder is 50-250 mesh; the steel base is carbon steel with a thickness of 0.5-5 mm; the thickness of the copper plating layer is 1-10 μm; the thickness of the aluminum-tin alloy layer is 0.1-0.6 mm; the manufacturing method comprises the following steps: S1, sintering copper powder: sintering copper powder on the surface of the steel strip where aluminum-tin alloy is needed to be compounded; the sintering amount of the copper powder is 200-500 grams per square meter; the steel strip needs to be degreased, derusted and plated with copper before sintering the copper powder; S2, laying aluminum-tin alloy powder: laying aluminum-tin alloy powder on the surface of the steel strip sintered with copper powder; the laying thickness of the aluminum-tin alloy powder is 0.3-2.0 mm; S3, first rolling: rolling the steel strip laid with aluminum-tin alloy powder through a rolling mill to roll and compound the aluminum-tin alloy powder on the steel strip to form a bimetallic composite steel strip; in the rolling process, the rolling deformation of the steel strip is 3-25%; S4, sintering: sintering the bimetallic composite steel strip in a sintering furnace, the sintering temperature is 300-500℃, and the sintering furnace atmosphere is air, nitrogen or argon; S5, second rolling: rolling the sintered bimetallic composite steel strip to the final size through a rolling mill, the rolling deformation is greater than 10%; S6, annealing: placing the bimetallic composite steel strip after the second rolling in an annealing furnace for annealing treatment, the annealing temperature is 300-500℃, and the annealing time is 0.5-5 hours.

2. The method for manufacturing an aluminum-tin alloy-steel bimetallic composite material according to claim 1, characterized in that, The sintering amount of the copper powder in step S1 is 300-400 grams per square meter.

3. The method for manufacturing an aluminum-tin alloy-steel bimetallic composite material according to claim 1, characterized in that, The particle size of the aluminum-tin alloy powder in step S2 is between 80-200 mesh.

4. The method for manufacturing an aluminum-tin alloy-steel bimetallic composite material according to claim 1, characterized in that, The rolling deformation of the steel strip in step S3 is 5%-15%.

5. The method for manufacturing an aluminum-tin alloy-steel bimetallic composite material according to claim 1, characterized in that, The sintering temperature of the bimetallic composite steel strip after rolling in step S4 is 380-480℃, and the sintering time is 0.5-1 hour.

6. The method for manufacturing an aluminum-tin alloy-steel bimetallic composite material according to claim 1, characterized in that, The deformation in the second rolling in step S5 is >30%; the annealing temperature of the composite material in step S6 is 350℃-450℃, the annealing time is 1-2 hours, and the composite material is air-cooled after annealing.

7. The method for manufacturing an aluminum-tin alloy-steel bimetallic composite material according to claim 1, characterized in that, The particle size of the copper powder is 80-180 mesh.

8. The method for manufacturing an aluminum-tin alloy-steel bimetallic composite material according to claim 1, characterized in that, The aluminum-tin alloy layer is AlSn20Cu or AlSn12SiCu alloy.

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