阅读说明：本技术 一种真空压铸实现真空钎焊的Al-Mn-Mg-Si-Ti-Sn铸造合金及其制备方法 (Al-Mn-Mg-Si-Ti-Sn casting alloy for realizing vacuum brazing by vacuum die casting and preparation method thereof ) 是由 林波 范滔 肖华强 姜云 于 2021-10-18 设计创作，主要内容包括：本发明公开了一种真空压铸实现真空钎焊的Al-Mn-Mg-Si-Ti-Sn铸造合金及其制备方法,其技术方案要点是：本发明通过化学成分设计、真空压铸成形、均匀化热处理、真空钎焊成形,制备出铝合金水冷散热器用Al-Mn-Mg-Si-Ti-Sn铸造合金新材料。采用本技术制备的铝合金新材料,其Mn含量接近共晶点,铸造性能优良,通过Mg,Si,Ti,Sn合金化,并采用真空压铸工艺,获得晶粒细小,晶内包含Mg-(2)Si等增强相,显著获得高强韧室温性能和导热性能的同时,由于其高熔点的合金成分设计,可以满足后续高温真空钎焊的要求,减少变形,有效提高了铝合金水冷散热器的生产效率,减少机加工时间,大幅降低成本。(The invention discloses an Al-Mn-Mg-Si-Ti-Sn casting alloy for realizing vacuum brazing by vacuum die casting and a preparation method thereof, and the key points of the technical scheme are as follows: the invention prepares the novel Al-Mn-Mg-Si-Ti-Sn casting alloy material for the aluminum alloy water-cooling radiator through chemical composition design, vacuum die-casting forming, homogenization heat treatment and vacuum brazing forming. The new aluminum alloy material prepared by the technology has the Mn content close to the eutectic point and excellent casting performance, and the obtained crystal grains are fine and have fine grains by alloying Mg, Si, Ti and Sn and adopting a vacuum die-casting processContaining Mg therein 2 The reinforcing phases such as Si and the like obviously obtain high-strength and high-toughness room temperature performance and heat conductivity, and due to the design of the high-melting-point alloy components, the requirement of subsequent high-temperature vacuum brazing can be met, the deformation is reduced, the production efficiency of the aluminum alloy water-cooling radiator is effectively improved, the machining time is reduced, and the cost is greatly reduced.)

1. The Al-Mn-Mg-Si-Ti-Sn casting alloy for realizing vacuum brazing by vacuum die casting is characterized by comprising the following components in percentage by mass: 1.6-2.4% of Mn, 0.45-0.9% of Mg, 0.2-0.6% of Si, 0.1-0.2% of Ti, 0.5-1.5% of Sn, the balance of Al and impurities, and the content of impurity Fe is less than or equal to 0.5%;

the Al-Mn-Mg-Si-Ti-Sn casting alloy has the normal-temperature tensile strength of more than or equal to 200MPa, the yield strength of more than or equal to 150MPa, the elongation of more than or equal to 15 percent and the heat conductivity of more than or equal to 180W/(m.K).

2. The Al-Mn-Mg-Si-Ti-Sn casting alloy for vacuum die casting vacuum brazing according to claim 1, wherein the Al-Mn-Mg-Si-Ti-Sn casting alloy is prepared by chemical composition design, vacuum die casting forming and homogenization heat treatment.

3. The Al-Mn-Mg-Si-Ti-Sn casting alloy for vacuum die casting vacuum brazing as claimed in claim 1, wherein the Al-Mn-Mg-Si-Ti-Sn casting alloy is vacuum brazing-welded with 4004 clad fins to obtain the aluminum alloy water-cooled heat sink.

4. A method for preparing an Al-Mn-Mg-Si-Ti-Sn casting alloy for vacuum brazing by vacuum die casting, which is applied to the Al-Mn-Mg-Si-Ti-Sn casting alloy for vacuum brazing by vacuum die casting according to any one of claims 1 to 3, comprising the steps of:

s1: heating high-purity aluminum to be molten, and then adding an aluminum-manganese intermediate alloy, an aluminum-magnesium intermediate alloy, an aluminum-silicon intermediate alloy, an aluminum-titanium intermediate alloy and pure tin according to the proportioned alloy components; after the furnace burden is completely melted, uniformly mixing to obtain an aluminum melt;

s2: adding a solid refining agent into the aluminum melt in the step S1, refining, degassing, standing, and slagging off to obtain refined molten metal;

s3: preheating a metal die to 250 ℃, and carrying out vacuum die-casting on the metal solution in the step S2 at 690-730 ℃ to obtain a required thin-wall structural part;

s4: homogenizing the structural member in the step S3, wherein the homogenizing temperature is 550-600 ℃, and the heat preservation time is 6-12h, so as to obtain a final structural member;

s5: cutting the 4004 solder into sheets covering the areas to be welded according to different welding positions, cleaning the solder and the structural part to be welded, wrapping the areas to be welded of the structural part with the solder, and performing brazing in a vacuum brazing furnace.

5. The method as claimed in claim 4, wherein the heating rate of the high purity aluminum is 10 ℃ per minute, the melting temperature of the high purity aluminum is 680 ℃ to 700 ℃, and the melting temperature of the master alloy is 700 ℃ to 720 ℃ in step S1.

6. The method for preparing Al-Mn-Mg-Si-Ti-Sn casting alloy for vacuum brazing by vacuum die casting according to claim 4, wherein in the step S2, the temperature of the refining treatment is 720-730 ℃, and the refining time is 10-15 min.

7. The method as claimed in claim 4, wherein in step S2, the degassing gas is Ar with a purity of more than 99.5% and degassing time of 10-20 min.

8. The method for preparing Al-Mn-Mg-Si-Ti-Sn casting alloy for vacuum brazing by vacuum die casting according to claim 4, wherein the standing time in the step S2 is 10min to 15 min.

9. The method as claimed in claim 4, wherein in step S3, the temperature of the metal mold is 200-300 ℃, the casting temperature is 690-730 ℃, the injection speed is 0.5-1.5m/S, the injection pressure is 30-75MPa, and the vacuum degree of the vacuum die casting process is less than or equal to 50 mbar.

10. The method of claim 4, wherein the vacuum brazing furnace has a vacuum degree of more than 4 in step S5_*10^-3Pa, and the welding temperature is 590-600 ℃.

Technical Field

The invention relates to the technical field of aluminum alloy vacuum die casting and welding, in particular to an Al-Mn-Mg-Si-Ti-Sn casting alloy for realizing vacuum brazing by vacuum die casting and a preparation method thereof.

Background

The aluminum water-cooling radiator in the electronic field not only radiates heat for a chip on a circuit board, but also provides positioning and installation of the circuit board and adhesion of sealing colloid. At present, the aluminum water-cooling radiator mainly adopts a mode of forging 6063 aluminum alloy with high heat conductivity and machining an aluminum plate to form a shell, and is subjected to vacuum brazing welding with 4004 coated fins. The 6063 shell is formed by forging and aluminum plate machining, so that the efficiency is low, the machining time is too long, the material loss is too large, and the cost is too high. The vacuum die casting can greatly improve the precision of the shell, improve the efficiency, reduce the machining loss and greatly reduce the production cost of the shell, and is an ideal choice for the aluminum water-cooling radiator shell.

At present, the die-casting aluminum alloy material is mainly ADC series aluminum-silicon alloy, the casting performance is good, but the problems of insufficient heat conductivity and too low melting point exist, and the subsequent vacuum brazing cannot be met, because the fin material used for the vacuum brazing is 4004 alloy Al-Si-Mg alloy, the welding temperature of the vacuum brazing is too high (generally 590-. And 6063 aluminum alloy is wrought aluminum alloy, so that the casting performance is too poor and the requirement of vacuum die casting cannot be met.

In addition, the 3-series Al-Mn-Mg-Si alloy has the characteristics of high heat conductivity and high melting point, but the Mn content is only 1 to 1.5 percent, and the castability is too poor. (1) In addition, Chinese invention patent with application number CN202110590679.4 is retrieved, and the invention discloses a high-strength, high-toughness, high-heat-conductivity and easy-welding aluminum-based composite material for a 5G base station and a preparation method thereof, wherein the method comprises the steps of increasing the content of Si on the basis of 3003 aluminum alloy, adding rare and precious metals such as Zr, Ti, B, Er, Sc, Y, Zn, Mg and the like, simultaneously adopting in-situ synthesis reaction to generate a large amount of nano particles, and simultaneously adopting an electromagnetic ultrasonic control double-roller continuous casting rolling process, lap welding and blow forming to form a strip. The method has complex alloy components and complex process, and does not relate to vacuum die casting and vacuum brazing processes. (2) The Chinese patent with the application number of CN201811405300.2 discloses an Al-Mn-Mg alloy with high Mn content and a preparation method thereof, the method increases the Mn content and the Mg content to 5.0 percent on the basis of 3000 series aluminum alloy, and develops an Al-Mn-Mg alloy sheet with high Mn content. (3) Further, the chinese patent application No. CN201910447015.5 discloses "an anodizable Al-Mn cast aluminum alloy and an anodizing process thereof", which is a method for developing an aluminum alloy with excellent anodizing properties by adding rare and noble metals such as Co, Sc, Ti, etc. to an Al-Mn aluminum alloy. The method has the advantages that the cost of adding a large amount of rare and precious metals is too high, the heat-conducting property of the alloy is influenced after the alloy is alloyed, the anodic oxidation property is mainly concerned, and the process does not involve vacuum die-casting and vacuum brazing processes.

Therefore, a new vacuum die-casting aluminum alloy material with high thermal conductivity, high melting point and excellent casting performance is urgently needed to be developed and meet the requirement of vacuum brazing.

Disclosure of Invention

In order to overcome the defects in the prior art, the invention aims to provide the Al-Mn-Mg-Si-Ti-Sn casting alloy for realizing vacuum brazing by vacuum die casting and the preparation method thereof, which can meet the requirement of subsequent high-temperature vacuum brazing, reduce deformation, effectively improve the production efficiency of the aluminum alloy water-cooling radiator, reduce machining time and greatly reduce cost.

The technical purpose of the invention is realized by the following technical scheme:

in a first aspect, an Al-Mn-Mg-Si-Ti-Sn casting alloy for realizing vacuum brazing by vacuum die casting is provided, and the Al-Mn-Mg-Si-Ti-Sn casting alloy comprises the following components in percentage by mass: 1.6-2.4% of Mn, 0.45-0.9% of Mg, 0.2-0.6% of Si, 0.1-0.2% of Ti, 0.5-1.5% of Sn, the balance of Al and impurities, and the content of impurity Fe is less than or equal to 0.5%;

the Al-Mn-Mg-Si-Ti-Sn casting alloy has the normal-temperature tensile strength of more than or equal to 200MPa, the yield strength of more than or equal to 150MPa, the elongation of more than or equal to 15 percent and the heat conductivity of more than or equal to 180W/(m.K).

Preferably, the Al-Mn-Mg-Si-Ti-Sn casting alloy is prepared by chemical composition design, vacuum die-casting forming and homogenization heat treatment.

Preferably, the Al-Mn-Mg-Si-Ti-Sn casting alloy can be subjected to vacuum brazing welding forming with a 4004 coated fin to obtain the aluminum alloy water-cooled radiator.

In a second aspect, there is provided a method for preparing an Al-Mn-Mg-Si-Ti-Sn casting alloy for vacuum die casting vacuum brazing, which is applied to the Al-Mn-Mg-Si-Ti-Sn casting alloy for vacuum die casting vacuum brazing according to any one of the first aspects, and comprises the following steps:

s1: heating high-purity aluminum to be molten, and then adding an aluminum-manganese intermediate alloy, an aluminum-magnesium intermediate alloy, an aluminum-silicon intermediate alloy, an aluminum-titanium intermediate alloy and pure tin according to the proportioned alloy components; after the furnace burden is completely melted, uniformly mixing to obtain an aluminum melt;

s2: adding a solid refining agent into the aluminum melt in the step S1, refining, degassing, standing, and slagging off to obtain refined molten metal;

s3: preheating a metal die to 250 ℃, and carrying out vacuum die-casting on the metal solution in the step S2 at 690-730 ℃ to obtain a required thin-wall structural part;

s4: homogenizing the structural member in the step S3, wherein the homogenizing temperature is 550-600 ℃, and the heat preservation time is 6-12h, so as to obtain a final structural member;

s5: cutting the 4004 solder into sheets covering the areas to be welded according to different welding positions, cleaning the solder and the structural part to be welded, wrapping the areas to be welded of the structural part with the solder, and performing brazing in a vacuum brazing furnace.

Preferably, in step S1, the temperature raising rate of the high purity aluminum is 10 ℃ per minute, the melting temperature of the high purity aluminum is 680 ℃ to 700 ℃, and the melting temperature of the master alloy is 700 ℃ to 720 ℃.

Preferably, in step S2, the temperature of the refining treatment is 720 to 730 ℃, and the refining time is 10 to 15 min.

Preferably, in step S2, the degassing gas is argon gas, the purity is greater than 99.5%, and the degassing time is 10min to 20 min.

Preferably, in step S2, the standing time is 10 to 15 min.

Preferably, in step S3, the temperature of the metal mold is 200-.

Preferably, in step S5, the vacuum degree of the vacuum brazing furnace is more than 4_*10^-3Pa, and the welding temperature is 590-600 ℃.

Compared with the prior art, the invention has the following beneficial effects:

1. the Al-Mn-Mg-Si-Ti-Sn casting alloy for realizing vacuum brazing by vacuum die casting improves the Mn content to 1.6-2.4 percent on the basis of 3003 and 6003 alloys so as to improve the melting point and the casting performance of the alloy and meet the production requirements of subsequent vacuum die casting and vacuum brazing; with addition of Mg and Si to the alloy, with the aim of forming Mg₂The Si reinforcing phase improves the obdurability of the alloy on the basis of not reducing the heat-conducting property of the alloy; in addition, Ti and Sn are added into the alloy, the main purpose is to refine crystal grains and improve the toughness of the alloy, meanwhile, the addition of Sn can compensate the reduction of heat conductivity brought by Ti, and finally, the Al-Mn-Mg-Si-Ti-Sn casting alloy which has high casting performance, high melting point, high toughness, high heat conductivity and easy welding is obtained, so that the production requirements of vacuum die casting and high-temperature vacuum brazing are met.

2. The invention can reduce deformation in the production and processing processes, effectively improves the production efficiency of the aluminum alloy water-cooling radiator, reduces the machining time and greatly reduces the cost; the production requirements of vacuum die casting and vacuum brazing of the water-cooled radiator can be met, and the requirements of shell parts in the fields of new energy automobiles and electronics on aluminum alloy materials can be met.

3. The preparation method of the Al-Mn-Mg-Si-Ti-Sn casting alloy for realizing vacuum brazing by vacuum die casting provided by the invention is used for producing shell parts such as aluminum water-cooling plates and the like, and meets the requirements of the subsequent vacuum brazing process.

4. The performance of the Al-Mn-Mg-Si-Ti-Sn casting alloy provided by the invention can reach: the tensile strength at normal temperature is more than or equal to 200MPa, the yield strength is more than or equal to 150MPa, the elongation is more than or equal to 15%, and the heat conductivity is more than or equal to 180W/(mK).

Drawings

The accompanying drawings, which are included to provide a further understanding of the embodiments of the invention and are incorporated in and constitute a part of this application, illustrate embodiment(s) of the invention and together with the description serve to explain the principles of the invention. In the drawings:

FIG. 1 is a schematic structural view of an Al-Mn-Mg-Si-Ti-Sn cast alloy in an example of the present invention, a being an as-cast structure and b being a uniformly heat-treated structure;

FIG. 2 is a schematic structural diagram of an Al-Mn-Mg-Si-Ti-Sn casting alloy in the embodiment of the invention after vacuum brazing welding with 4004 solder.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is further described in detail below with reference to examples and accompanying drawings, and the exemplary embodiments and descriptions thereof are only used for explaining the present invention and are not meant to limit the present invention.

Example 1

In the embodiment of the invention, the Al-Mn-Mg-Si-Ti-Sn series cast aluminum alloy for realizing vacuum brazing by adopting vacuum die casting comprises the following components in percentage by mass: 1.6 parts of Mn, 0.45 part of Mg, 0.2 part of Si, 0.1 part of Ti, 0.5 part of Sn, 0.1 part of Fe and the balance of Al.

Adding a pure aluminum ingot into a resistance furnace, melting and preserving heat to 700 ℃, and then adding Al-10Mn intermediate alloy, Al-5Mg intermediate alloy, Al-20Si intermediate alloy, Al-10Ti intermediate alloy, pure Sn and the like in proportion to adjust the alloy components to the design values; adding a solid refining agent into the molten aluminum, refining, degassing, standing, and slagging off to obtain refined molten metal; pouring molten aluminum into a vacuum die casting machine, and carrying out vacuum die casting to form a part, wherein the pouring temperature is 690 ℃, the die temperature is 200 ℃, the injection speed is 0.5m/s, the injection pressure is 30MPa, and the vacuum degree of vacuum die casting treatment is 10 mbar. And homogenizing the casting at 550 ℃ for 6 h. And putting the casting subjected to heat treatment into a vacuum brazing furnace, and performing vacuum brazing on the casting and the fin coated with the 4004 aluminum alloy to obtain the water-cooled radiator, wherein the vacuum brazing temperature is 590 ℃. The test result shows that the normal-temperature tensile strength of the casting is 204MPa, the yield strength is 165MPa, and the elongation is 25%. The thermal conductivity of the material was 189W/m.K as measured by a hot wire thermal conductivity meter.

FIG. 1 shows the as-cast and homogenized heat-treated structure of Al-Mn-Mg-Si-Ti-Sn prepared by vacuum die casting, wherein a is the as-cast structure and b is the homogenized heat-treated structure; as can be seen from FIG. 1, the alloy structure is denser, the second phases in Chinese character shapes are distributed on the aluminum matrix, after the homogenization heat treatment, the second phases are remarkably reduced, part of the second phases are dissolved into the matrix, and part of the second phases are granulated.

As shown in fig. 2, when the welding zone of the material of the part (i.e., the structural member) in the embodiment is observed, the welding seam of the welding zone is neat and beautiful, and no "fish-scale" welding seam is generated, and a part of a sample is taken from the welding zone, and the appearance and the structure of the welding zone are observed by a microscope, so that the structure is dense, and the welding melting zone is tightly combined.

Example 2

In the embodiment of the invention, the Al-Mn-Mg-Si-Ti-Sn series cast aluminum alloy for realizing vacuum brazing by adopting vacuum die casting comprises the following components in percentage by mass: 2.0 parts of Mn, 0.6 part of Mg, 0.4 part of Si, 0.15 part of Ti, 1.0 part of Sn, 0.3 part of Fe and the balance of Al.

Adding a pure aluminum ingot into a resistance furnace, melting and preserving heat to 700 ℃, and then adding Al-10Mn intermediate alloy, Al-5Mg intermediate alloy, Al-20Si intermediate alloy, Al-10Ti intermediate alloy, pure Sn and the like in proportion to adjust the alloy components to the design values; adding a solid refining agent into the molten aluminum, refining, degassing, standing, and slagging off to obtain refined molten metal; and pouring the molten aluminum into a vacuum die casting machine, and carrying out vacuum die casting to form a part, wherein the pouring temperature is 710 ℃, the die temperature is 250 ℃, the injection speed is 1m/s, the injection pressure is 50MPa, and the vacuum degree of vacuum die casting treatment is 20 mbar. The casting was homogenized at a temperature of 590 ℃. The test result shows that the normal-temperature tensile strength of the casting is 235MPa, the yield strength is 185MPa, and the elongation is 20%. The thermal conductivity of the material was 185W/m.K as measured by a hot wire thermal conductivity meter. Observing the welding area of the part material in the embodiment, the welding line of the welding area is found to be neat and attractive in appearance, no fish scale-shaped welding line is generated, a part of sample is taken in the welding area, the appearance and the tissue of the welding area are observed through a microscope, the tissue is found to be compact, and the welding melting area is tightly combined.

Example 3

In the embodiment of the invention, the Al-Mn-Mg-Si-Ti-Sn series cast aluminum alloy for realizing vacuum brazing by adopting vacuum die casting comprises the following components in percentage by mass: mn2.4, Mg0.9, Si0.6, Ti 0.2, Sn 1.5, Fe 0.5, and the balance of Al.

Adding a pure aluminum ingot into a resistance furnace, melting and preserving heat to 700 ℃, and then adding Al-10Mn intermediate alloy, Al-5Mg intermediate alloy, Al-20Si intermediate alloy, Al-10Ti intermediate alloy, pure Sn and the like in proportion to adjust the alloy components to the design values; adding a solid refining agent into the molten aluminum, refining, degassing, standing, and slagging off to obtain refined molten metal; pouring molten aluminum into a vacuum die casting machine, and carrying out vacuum die casting to form a part, wherein the pouring temperature is 730 ℃, the die temperature is 300 ℃, the injection speed is 2.5m/s, the injection pressure is 75MPa, and the vacuum degree of vacuum die casting treatment is 30 mbar. The casting was homogenized at a temperature of 600 ℃. The test result shows that the normal-temperature tensile strength of the casting is 245MPa, the yield strength is 185MPa, and the elongation is 18%. The thermal conductivity of the material was measured to be 180W/m.K by a hot wire method. Observing the welding area of the part material in the embodiment, the welding line of the welding area is found to be neat and attractive in appearance, no fish scale-shaped welding line is generated, a part of sample is taken in the welding area, the appearance and the tissue of the welding area are observed through a microscope, the tissue is found to be compact, and the welding melting area is tightly combined.

From the above results, the Al-Mn-Mg-Si-Ti-Sn casting alloy provided by the invention has thermal conductivity and weldability close to 3003 and 6063 alloy, and the mechanical property is not weaker than that of the conventional 6063 alloy. The method of vacuum die casting and vacuum brazing can completely solve the problem of welding the complex shell parts and the fins of the radiator. And the utilization rate of materials is greatly improved, the production period of parts is shortened, the economic cost is saved to a great extent, and the method has great economic benefit.

The above-mentioned embodiments are intended to illustrate the objects, technical solutions and advantages of the present invention in further detail, and it should be understood that the above-mentioned embodiments are merely exemplary embodiments of the present invention, and are not intended to limit the scope of the present invention, and any modifications, equivalent substitutions, improvements and the like made within the spirit and principle of the present invention should be included in the scope of the present invention.