AU2021103058A4

AU2021103058A4 - Aluminum alloy, and manufacturing process and use thereof

Info

Publication number: AU2021103058A4
Application number: AU2021103058A
Authority: AU
Inventors: Xiaoli Ding; Bing Zhang; Wang ZHOU
Original assignee: Guangdong Hoshion Industrial Aluminum Co Ltd
Current assignee: Guangdong Hoshion Industrial Aluminum Co Ltd
Priority date: 2020-12-17
Filing date: 2021-06-03
Publication date: 2021-07-29
Anticipated expiration: 2029-06-03
Also published as: CN112708811B; CN112708811A

Abstract

The present disclosure belongs to the technical field of alloys, and particularly relates to an aluminum alloy, and a manufacturing process and use thereof. The aluminum alloy provided in the present disclosure includes the following elements, in mass percentage: Cu: 0.08% to 0.12%, Mn: 0.07% to 0.10%, Si: 0.08% to 0.12%, Mg: 0.15% to 0.20%, Li: 0.02% to 0.06%, Ti: 0.005% to 0.008%, and Al and unavoidable impurities: the balance; where 0.12 wt.% < Li + Mn < 0.15 wt.%. The examples show that the aluminum alloy provided by the present disclosure has a tensile strength of 152 MPa to 170 MPa; and a product extruded from the aluminum alloy has a smooth surface without tearing and excellent extrusion performance, which can meet the requirements of thin-walled small-cavity structure profiles on tensile strength and extrusion performance. -1/1 DRAWINGS Melting, refining, on-line Homogenizat grain refinement, and on-line Casting iontreatment degassing and filtration Aging Deformation treatment treatment FIG. 1 FIG. 2 Small -al - -cavity Wall DDDDDDD_ _ _ _ thickness FIG. 3

Description

-1/1

DRAWINGS

Melting, refining, on-line Homogenizat grain refinement, and on-line Casting iontreatment degassing and filtration

Aging Deformation treatment treatment

FIG. 1

FIG. 2

Small

DDDDDDD_ -al - -cavity

Wall thickness __ _ FIG. 3

ALUMINUM ALLOY, AND MANUFACTURING PROCESS AND USE THEREOF TECHNICAL FIELD

[01] The present disclosure belongs to the technical field of alloys, and particularly relates to an aluminum alloy, and a manufacturing process and use thereof.

BACKGROUNDART

[02] A heat exchanger (also known as heat interchanger or heat exchange equipment) is a device that can transfer heat from a hot fluid to a cold fluid to meet specified process requirements, which is an industrial application for convective heat transfer and heat transfer and has multiple parallel rectangular channels. In order to improve a heat transfer effect, the parallel rectangular channels of a heat exchanger are designed smaller and smaller to increase a specific surface area (SSA) and a heat dissipation area, and an aluminum alloy wall thickness of a heat exchanger is designed thinner and thinner. For example, the current parallel rectangular channels of a heat exchanger have a minimum area of 2 mm 2 and a wall thickness of 0.5 mm, and such thin-walled small-cavity structures have higher and higher requirements on the extrudability of an aluminum alloy used in a heat exchanger.

[03] Among existing aluminum alloys, the 1000 series aluminum alloy has the advantages such as high purity and easy extrusion, but exhibits too-low strength that cannot meet the basic strength requirements of heat exchangers; and the 3000 series aluminum alloy, when used in the production of aluminum alloy heat exchangers with small wall thickness and rectangular small cavities, shows large shape resistance and is easily adhered to a die land of an extrusion die, which causes a cavity to be scratched and makes it difficult to extrude a thin-walled heat exchanger with many small heat dissipation channels. Therefore, the failure of extrusion forming is common. The current aluminum alloys cannot achieve the production of thin-walled small-cavity structures on the basis of ensuring prominent strength and extrusion performance, and thus cannot meet the production and use requirements of heat exchangers.

SUMMARY

[04] In view of this, the present disclosure is intended to provide an aluminum alloy and a manufacturing process thereof. The aluminum alloy provided by the present disclosure has the characteristics of excellent extrusion performance and high tensile strength, which can meet the requirements of thin-walled small-cavity structures on strength and extrusion performance.

[05] In order to realize the objective of the present disclosure, the present disclosure provides the following technical solutions:

[06] The present disclosure provides an aluminum alloy, including the following elements, in mass percentage:

[07] Cu: 0.08% to 0.12%, Mn: 0.07% to 0.10%, Si: 0.08% to 0.12%, Mg: 0.15% to 0.20%, Li: 0.02% to 0.06%, Ti: 0.005% to 0.008%, and Al and unavoidable impurities: the balance;

[08] where 0.12 wt.% < Li + Mn < 0.15 wt.%.

[09] Preferably, the unavoidable impurities may include Fe and non-Fe impurities; and in mass percentage, Fe may have a content of < 0.08%, a single element among the non-Fe impurities may have a content of < 0.05%, and the non-Fe impurities may have a total content of < 0.15%.

[10] Preferably, the aluminum alloy may have a tensile strength of 150 MPa to 170 MPa.

[11] Preferably, the aluminum alloy can be extruded into a profile with a limit wall thickness of 0.5 mm; and when the aluminum alloy is extruded into a small-cavity profile, a single small cavity may have a limit section area of 2 mm 2 and there may be 5 to 50 small cavities.

[12] The present disclosure also provides a manufacturing process of the aluminum alloy according to the above technical solution, including the following steps:

[13] subjecting alloy raw materials to smelting and casting in sequence to obtain an aluminum alloy ingot, where the smelting includes melting, refining, on-line grain refinement, and on-line degassing and filtration that are conducted in sequence; and

[14] subjecting the aluminum alloy ingot to homogenization treatment, deformation treatment, quenching, and aging treatment in sequence to obtain the aluminum alloy.

[15] Preferably, the melting may be conducted at 740°C to 760°C;

[16] the refining may be conducted at 730°C to 780°C for 10 min to 40 min;

[17] the grain refinement may be conducted at 710°C to 750°C; and

[18] the on-line degassing and filtration may include degassing box filtration, foam ceramic filter plate filtration, and tubular filter box filtration that are conducted in sequence.

[19] Preferably, the homogenization treatment may be conducted at a holding temperature of 520°C to 540°C and a holding time of 4 h to 8 h.

[20] Preferably, the deformation treatment may be conducted at 450°C to 500°C.

[21] Preferably, the aging treatment may be conducted at a holding temperature of 200°C to 210°C and a holding time of 1 h to 3 h.

[22] The present disclosure also provides use of the aluminum alloy according to the above technical solution or an aluminum alloy manufactured by the manufacturing process according to the above technical solution as a thin-walled small-cavity structure profile in heat exchangers.

[23] The present disclosure provides an aluminum alloy, including the following elements, in mass percentage: Cu: 0.08% to 0.12%, Mn: 0.07% to 0.10%, Si: 0.08% to 0.12%, Mg: 0.15% to 0.20%, Li: 0.02% to 0.06%, Ti: 0.005% to 0.008%, and Al and unavoidable impurities: the balance; where 0.12 wt.% < Li + Mn< 0.15 wt.%.

[24] In the present disclosure, Al provides a matrix alloying element; Cu, Si, and Mg play a role of solid solution strengthening, and Si and Mg can also form a Mg2Si strengthening phase to enhance a strength of the aluminum alloy; Mn and Li are microalloying elements, Mn and Li can undergo the following phase change reactions: Al + Mn -- MnAl6 and Al + Li -- A13Li, and generated A 3Li and MnAl 6 are fine dispersed phases with high thermodynamic stability, which helps to inhibit the recrystallization and grain growth of the aluminum alloy; the addition of Mn is also beneficial to the spheroidization of hard particles of unavoidable impurities, promotes the spheroidization of the needle-like Fe-containing phases, can eliminate the negative influence of the Fe impurity element, and helps to improve the extrusion performance of the alloy; and Ti is beneficial to the grain refinement of the ingot and the improvement in the uniformity of components in the aluminum alloy.

[25] In addition, in the present disclosure, Si, Mg, and Cu contents are controlled within corresponding content ranges, which helps to ensure a strength of the aluminum alloy, avoids large resistance of the aluminum alloy to extrusion deformation and deterioration of extrusion performance, and can also reduce an electrical potential between a grain boundary and an interior of a grain to avoid increased sensitivity to stress corrosion and grain boundary corrosion; Li and Mn contents and a relationship between the two are controlled, which helps to ensure that the aluminum alloy has a recrystallized structure with fine grains above grade 5 after being extruded, effectively prevent the appearance of coarse recrystallized structures or coarse intermetallic compounds such that a mixed grain structure in which coarse recrystallized structures and fibrous crystal structures coexist is formed, and avoid the deterioration of the strength and extrusion performance of the aluminum alloy; and a Ti content can be controlled within a corresponding content range, which is beneficial to grain refinement, and helps to avoid the agglomeration and growth of Ti-containing particles in the ingot, the failure of continuous production due to the appearance of white line strip defects and discontinuous scratched thin-walled regions in an extruded product, the excessively-large grains (greater than 500 m) in the ingot, the inhomogeneous composition and structure of the ingot, and the

I deterioration of extrusion performance and mechanical properties of the aluminum alloy.

[26] Test results in the examples show that the aluminum alloy provided by the present disclosure has a tensile strength of 152 MPa to 170 MPa; and a product extruded from the aluminum alloy has a smooth surface without tearing and excellent extrusion performance.

[27] The present disclosure also provides a manufacturing process of the aluminum alloy according to the above technical solution, including the following steps: subjecting alloy raw materials to smelting and casting in sequence to obtain an aluminum alloy ingot, where the smelting includes melting, refining, on-line grain refinement, and on-line degassing and filtration that are conducted in sequence; and subjecting the aluminum alloy ingot to homogenization treatment, deformation treatment, quenching, and aging treatment in sequence to obtain the aluminum alloy. In the present disclosure, the aluminum alloy melt obtained from the melting is deeply purified by refining and on-line degassing and filtration, which greatly improves the cleanliness of the aluminum alloy melt, reduces the inclusion of gases and impurities in the aluminum alloy, and fundamentally reduce the root causes of scratching and tearing of an aluminum alloy profile during extrusion. The homogenization treatment helps to eliminate the macrosegregation and microsegregation of alloying elements in the ingot, such that the alloying elements and the coarse compounds are fully solutionized, the spheroidization of an impurity phase (Fe) is improved, and fine dispersoids are formed; and the aging treatment helps to precipitate the strengthening phase in the aluminum alloy and improve the strength of the aluminum alloy.

BRIEF DESCRIPTION OF DRAWINGS

[28] FIG. 1 is a flow chart of the manufacturing process of the aluminum alloy according to the present disclosure;

[29] FIG. 2 is a metallograph of the aluminum alloy provided in Example 1 of the present disclosure; and

[30] FIG. 3 is a schematic diagram of an extrusion profile for a heat exchanger.

DETAILED DESCRIPTION OF THE EMBODIMENTS

[31] The present disclosure provides an aluminum alloy, including the following elements, in mass percentage:

[32] Cu: 0.08% to 0.12%, Mn: 0.07% to 0.10%, Si: 0.08% to 0.12%, Mg: 0.15% to 0.20%, Li: 0.02% to 0.06%, Ti: 0.005% to 0.008%, and Al and unavoidable impurities: the balance;

[33] where 0.12 wt.% < Li + Mn < 0.15 wt.%.

A

[34] In mass percentage, the aluminum alloy of the present disclosure may include 0.08% to 0.12%, preferably 0.085% to 0.115%, and more preferably 0.09% to 0.11% of Cu. In the present disclosure, Cu plays a role of solid solution strengthening, which helps to improve the strength of the aluminum alloy; and a Cu content is controlled within a specified range, which helps to ensure the strength of the aluminum alloy, and avoids large resistance of the aluminum alloy to extrusion deformation and deterioration of extrusion performance.

[35] In mass percentage, the aluminum alloy of the present disclosure may include 0.07% to 0.10%, preferably 0.075% to 0.095%, and more preferably 0.08% to 0.09% of Mn. In the present disclosure, Mn forms a MnAl 6 phase with Al, and the addition of Mn is conducive to the spheroidization of hard particles in a Fe phase, the elimination of the negative influence of the Fe impurity element, and the improvement of the extrusion performance of the alloy; and a Mn content is controlled at 0.07 wt.% to 0.10 wt.%, which helps to improve the plasticity, weldability, heat resistance, and corrosion resistance of the aluminum alloy, and avoids large resistance to extrusion deformation and serious deterioration of extrusion performance.

[36] In mass percentage, the aluminum alloy of the present disclosure may include 0.08% to 0.12%, preferably 0.085% to 0.115%, and more preferably 0.09% to 0.11% of Si. In the present disclosure, Si plays a role of solid solution strengthening.

[37] In mass percentage, the aluminum alloy of the present disclosure may include 0.15% to 0.20%, preferably 0.155% to 0.195%, and more preferably 0.16% to 0.19% of Mg. In the present disclosure, Mg plays a role of solid solution strengthening, which is conducive to the grain refinement and strength improvement of the aluminum alloy; Si and Mg can form a Mg2Si strengthening phase, which helps to enhance a strength of the aluminum alloy; and Si and Mg contents are controlled within corresponding content ranges, which helps to ensure a strength of the aluminum alloy and avoids large resistance of the aluminum alloy to extrusion deformation and deterioration of extrusion performance.

[38] In mass percentage, the aluminum alloy of the present disclosure may include 0.02% to 0.06%, preferably 0.025% to 0.055%, and more preferably 0.03% to 0.05% of Li. In the present disclosure, Mn and Li can undergo the following phase change reactions: Al + Mn - MnAl6 and Al + Li -- A13Li, and generated A3Li and MnAl6 are fine dispersed phases with high thermodynamic stability, which helps to inhibit the recrystallization and grain growth of the aluminum alloy.

[39] In mass percentage, the aluminum alloy of the present disclosure may include 0.005% to 0.008%, preferably 0.0055% to 0.0075%, and more preferably 0.006% to 0.007% of Ti. In the present disclosure, Ti is beneficial to the grain refinement of the ingot and the improvement

I: in the uniformity of components in the aluminum alloy; and a Ti content can be controlled within a corresponding content range, which is beneficial to grain refinement, and helps to avoid the agglomeration and growth of Ti-containing particles in the ingot, the failure of continuous production due to the appearance of white line strip defects and discontinuous scratched thin-walled regions in an extruded product, the excessively-large grains (greater than 500 m) in the ingot, the inhomogeneous composition and structure of the ingot, and the deterioration of extrusion performance and mechanical properties of the aluminum alloy.

[40] In mass percentage, the aluminum alloy of the present disclosure may include the balance of Al and unavoidable impurities.

[41] In the present disclosure, Al is a matrix alloying element.

[42] In the present disclosure, the unavoidable impurities may include Fe and non-Fe impurities. In the present disclosure, in mass percentage, Fe in the unavoidable impurities may have a content preferably of < 0.08%, more preferably of < 0.07%, and further more preferably of < 0.05%. In the present disclosure, the impurity element Fe may form the hard and brittle needle-like AlFeSi series intermetallic compound, and the compound is hard, will increase the difficulty of extrusion, and often becomes a root cause of scratching and tearing of a profile during extrusion, thus deteriorating the extrusion performance of the aluminum alloy. Therefore, in the present disclosure, the Fe content needs to be strictly controlled, and a Mn content in the aluminum alloy is controlled at 0.07% to 0.10%, such that the spheroidization of the needle-like Fe-containing phase is promoted and the negative influence of the Fe impurity element is eliminated.

[43] In the present disclosure, in mass percentage, a single element among the non-Fe impurities may have a content preferably of < 0.05% and more preferably of < 0.04%; and the non-Fe impurities may have a total content preferably of < 0.15%, more preferably of 0.13%, and further more preferably of < 0.1%. In the present disclosure, the non-Fe impurities may preferably include one or more from the group consisting of Na, Ca, V, and B.

[44] In the present disclosure, Li and Mn need to have a total content as follows: 0.12 wt.% < Li + Mn< 0.15 wt.%, preferably 0.125 wt.% Li + Mn < 0.145 wt.%, and more preferably 0.13 wt.% Li + Mn< 0.14 wt.%. In the present disclosure, a relationship between Li and Mn contents is controlled, which helps to ensure that the aluminum alloy has a recrystallized structure with fine grains above grade 5 after being extruded, effectively prevent the appearance of coarse recrystallized structures above grade 5 or coarse intermetallic compounds such that a mixed grain structure in which coarse recrystallized structures and fibrous crystal structures coexist is formed, avoid the deterioration of the strength and extrusion performance of the aluminum alloy, balance a relationship between the strength and the extrusion performance of the aluminum alloy, and meet the requirements of a thin-walled small-cavity structure on the strength and extrusion performance.

[45] In the present disclosure, the aluminum alloy may have a tensile strength preferably of 150 MPa to 170 MPa. In the present disclosure, the aluminum alloy can be extruded into a profile with a limit wall thickness preferably of 0.5 mm; and when the aluminum alloy is extruded into a small-cavity profile, a single small cavity may have a limit section area preferably of 2 mm 2 and there may preferably be 5 to 50 small cavities.

[46] The present disclosure also provides a manufacturing process of the aluminum alloy according to the above technical solution, including the following steps:

[47] subjecting alloy raw materials to smelting and casting in sequence to obtain an aluminum alloy ingot, where the smelting includes melting, refining, on-line grain refinement, and on-line degassing and filtration that are conducted in sequence; and

[48] subjecting the aluminum alloy ingot to homogenization treatment, deformation treatment, quenching, and aging treatment in sequence to obtain the aluminum alloy.

[49] FIG. 1 is a flow chart of the manufacturing process of the aluminum alloy according to the present disclosure. The manufacturing process of the aluminum alloy provided by the present disclosure will be described in detail below in conjunction with FIG. 1.

[50] In the present disclosure, alloy raw materials are subjected to smelting and casting in sequence to obtain an aluminum alloy ingot, where the smelting includes melting, refining, on-line grain refinement, and on-line degassing and filtration that are conducted in sequence.

[51] In the present disclosure, alloy raw materials are subjected to smelting to obtain an aluminum alloy ingot, where the smelting includes melting, refining, on-line grain refinement, and on-line degassing and filtration that are conducted in sequence.

[52] The present disclosure has no specific limitations on the alloy raw materials, and any alloy raw materials that can meet the aluminum alloy element composition requirements may be adopted.

[53] In the present disclosure, the melting may be conducted at a temperature preferably of 740°C to 760°C and more preferably of 745°C to 755°C; and the melting may be conducted preferably for 1 h to 5 h and more preferably for 3 h to 4 h. In the present disclosure, the melting may be conducted preferably with a tilting-type melting furnace. In the present disclosure, a first aluminum alloy melt is obtained through the melting.

[54] In the present disclosure, the refining may preferably include: mixing the first aluminum alloy melt, a refining agent, and a slag forming agent, and conducting refining at an argon atmosphere to obtain a second aluminum alloy melt. In the present disclosure, the refining agent may preferably be a 6AB refining agent; and in mass percentage, the 6AB refining agent may preferably include the following elements: K: 15% to 25%, Na: 15% to %, Al: 0% to 10%, Si: 2% to 10%, Cl: 10% to 30%, F: 5% to 20%, and impurities: the balance. In the present disclosure, relative to the first aluminum alloy melt, the refining agent may be used at an amount preferably of 0.5 kg/t to 1 kg/t and more preferably of 0.6 kg/t to 0.9 kg/t. In the present disclosure, the slag forming agent may preferably be one or more from the group consisting of K, Al, Si, Cl, F, Ni, Pb, Sn, B, Be, Ca, Na, and V. In the examples of the present disclosure, the slag forming agent may preferably be a D4 slag forming agent; and in mass percentage, the D4 slag forming agent may preferably include the following elements: K: 8% to 12%, Na: 10% to 20%, Al: 0% to 10%, Si: 3% to 15%, Cl: 20% to 30%, and F: 20% to %. In the present disclosure, relative to the first aluminum alloy melt, the slag forming agent may be used at an amount preferably of 0.5 kg/t to 1 kg/t and more preferably of 0.6 kg/t to 0.9 kg/t. In the present disclosure, the argon may be introduced at a flow rate preferably of 1 m3 /h to 2 m 3 /h and more preferably of 1.2 m 3 /h to 2 m3 /h. In the present disclosure, the refining may be conducted at a temperature preferably of 730°C to 780°C and more preferably of 740°C to 760°C; and the refining may be conducted preferably for 10 min to 40 min and more preferably for 15 min to 30 min.

[55] After the refining, the present disclosure may preferably further include: subjecting the second aluminum alloy melt to slagging-off and standing. The present disclosure has no specific limitations on the slagging-off, and slagging-off well known to those skilled in the art may be adopted. In the present disclosure, the standing may be conducted preferably for 10 min to 40 min and more preferably for 15 min to 30 min. The present disclosure preliminarily realizes the degassing and impurity removal for the second aluminum alloy melt through refining at an argon atmosphere.

[56] In the present disclosure, the on-line grain refinement may preferably include: mixing the second aluminum alloy melt with a grain refining agent, and conducting on-line grain refinement to obtain a third aluminum alloy melt. In the present disclosure, the grain refining agent may preferably be aluminum titanium boron wire, which may have a chemical composition preferably of Al-3Ti-1B. In the present disclosure, the aluminum titanium boron wire may preferably be added to the second aluminum alloy melt at a rate preferably determined according to the following formula:

[57] addition rate (m/min) = [number of aluminum alloy ingot cast holes x aluminum alloy ingot weight per meter x casting speed x (target Ti content in aluminum alloy - Ti content in

Q raw aluminum ingot)]/(Ti content in aluminum titanium boron wire x aluminum titanium boron wire weight per meter);

[58] where the aluminum alloy ingot weight per meter and the aluminum titanium boron wire weight per meter are expressed in kg, the casting speed is expressed in m/min, and an absolute value is taken for each parameter in the calculation formula.

[59] In the present disclosure, the on-line degassing and filtration may preferably include degassing box filtration, foam ceramic filter plate filtration, and tubular filter box filtration that are conducted in sequence. In the present disclosure, the on-line degassing and filtration may preferably include: allowing the third aluminum alloy melt to flow through a degassing box, a foam ceramic filter plate, and a tubular filter box arranged on a chute in sequence to obtain a fourth aluminum alloy melt. In the present disclosure, in the degassing box, a rotor may have a rotational speed preferably of 400 rpm to 500 rpm and more preferably of 420 rpm to 480 rpm; and argon may be introduced at a flow rate preferably of 2.0 m3 /h to 2.55 m3 /h and more preferably of 2.05 m3/h to 2.4 m3 /h. In the present disclosure, the foam ceramic filter plate may have a porosity preferably of 80 ppi. In the present disclosure, in the tubular filter box, a tubular filter may have a temperature preferably of 810°C to 880°C and more preferably of 820°C to 870°C.

[60] In the present disclosure, the casting may be conducted at a temperature preferably of 700°C to 730°C and more preferably of 705°C to 725°C. In the present disclosure, the casting may be conducted at a speed preferably of 0.150 m/min to 0.250 m/min and more preferably of 0.170 m/min to 0.230 m/min. The present disclosure has no specific limitations on the number of aluminum alloy cast holes in the casting, and a number of cast holes well known to those skilled in the art may be adopted.

[61] In the present disclosure, after an alloy ingot is obtained, the aluminum alloy ingot is subjected to homogenization treatment, deformation treatment, quenching, and aging treatment in sequence to obtain the aluminum alloy.

[62] In the present disclosure, the aluminum alloy ingot is subjected to homogenization treatment to obtain a homogenized ingot.

[63] In the present disclosure, the homogenization treatment may be conducted at a holding temperature preferably of 520°C to 540°C and more preferably of 525°C to 535°C; and the homogenization treatment may be conducted at a holding time preferably of 4 h to 8 h and more preferably of 4.5 h to 7.5 h. In the present disclosure, the homogenization treatment helps to eliminate the macrosegregation and microsegregation of alloying elements in the ingot, such that the alloying elements and the coarse compounds are fully solutionized and fine dispersoids

a are formed.

[64] In the present disclosure, after the homogenization treatment, the obtained homogenized ingot may preferably be cooled to room temperature; and the cooling may preferably refer to air-cooling.

[65] In the present disclosure, after a homogenized ingot is obtained, the homogenized ingot is subjected to deformation treatment and quenching in sequence to obtain a deformed aluminum alloy.

[66] In the present disclosure, the deformation treatment may be conducted at a temperature preferably of 450°C to 500°C and more preferably of 455°C to 495°C. In the present disclosure, the temperature for the deformation treatment may preferably be obtained by heating based on room temperature; and a rate for the heating may be preferably 6°C/min to 9°C/min and more preferably 8°C/min to 9°C/min. In the present disclosure, the deformation treatment may preferably be extrusion. In the present disclosure, the deformation treatment may be conducted preferably with a forward extruder. In the present disclosure, the extrusion may be conducted at a speed preferably of 20 m/min to 25 m/min and more preferably of 21 m/min to 24 m/min. In the present disclosure, the extrusion may be conducted at an extrusion ratio preferably of 50 to 100 and more preferably of 55 to 95. In the present disclosure, a die for the extrusion may have a temperature preferably of 450°C to 480°C and more preferably of 455°C to 475°C. In the present disclosure, the deformation treatment helps to realize the solid solution of an alloy strengthening phase and obtain a desired product prototype, and is also conducive to the realization of accurate process control of a product.

[67] In the present disclosure, before the extrusion, 1050 pure aluminum ingot drainage may preferably be conducted; and the 1050 pure aluminum ingot drainage may preferably include: after extruding the pure aluminum ingot, extruding the homogenized ingot. In the present disclosure, 1 to 3 pure aluminum ingots may preferably be used in the 1050 pure aluminum ingot drainage; the pure aluminum ingot may be extruded at a speed preferably of 10 m/min to 15 m/min and more preferably of 11 m/min to 14 m/min; and the pure aluminum ingot may have a temperature preferably of 500°C to 520°C and more preferably of 505°C to 515°C. The present disclosure uses the 1050 pure aluminum ingot with a small deformation resistance for drainage, which is beneficial to the smooth deformation of an aluminum alloy with high strength.

[68] In the present disclosure, the quenching may preferably refer to on-line air blast quenching. In the present disclosure, the quenching may be conducted at a cooling rate preferably of > 100°C/min and more preferably of 100°C/min to 200°C/min. In the present

iA disclosure, the quenching is beneficial to the formation of a supersaturated solid solution, which lays a foundation for subsequent aging.

[69] In the present disclosure, after a deformed aluminum alloy is obtained, the deformed aluminum alloy is subjected to aging treatment to obtain the aluminum alloy.

[70] In the present disclosure, the aging treatment may be conducted at a holding temperature preferably of 200°C to 210°C and more preferably of 202°C to 208°C; and the aging treatment may be conducted at a holding time preferably of 1h to 3 h and more preferably of 1.5 h to 2.5 h. In the present disclosure, the holding temperature for the aging treatment may preferably be obtained by heating based on room temperature; and a rate for the heating may be preferably 2°C/min to 10°C/min and more preferably 3C/min to 5°C/min. In the present disclosure, the aging treatment helps to precipitate the strengthening phase in the aluminum alloy and improve a strength of the aluminum alloy; and aging treatment conducted under the conditions specified in the present disclosure can ensure the strength and extrusion performance of the aluminum alloy to avoid strength reduction and difficult extrusion of the aluminum alloy.

[71] The present disclosure also provides use of the aluminum alloy according to the above technical solution or an aluminum alloy manufactured by the manufacturing process according to the above technical solution as a thin-walled small-cavity structure profile in heat exchangers.

[72] In the present disclosure, preferably, the aluminum alloy may be directly used for a heat exchanger forming process, and a thin-walled small-cavity profile obtained from the forming process may be used as a main component of the heat exchanger. The present disclosure has no specific limitations on the heat exchanger forming process, and a heat exchanger forming process well known to those skilled in the art may be adopted.

[73] To further illustrate the present disclosure, the aluminum alloy and the manufacturing process and use thereof provided in the present disclosure are described in detail below with reference to examples, but the examples should not be interpreted as a limitation to the protection scope of the present disclosure. Apparently, the described examples are merely some rather than all of the examples of the present disclosure. All other examples obtained by a person of ordinary skill in the art based on the examples of the present disclosure without creative efforts shall fall within the protection scope of the present disclosure.

[74] Example 1

[75] In mass percentage, an aluminum alloy with the following elementary composition was designed: Cu: 0.08%, Mn: 0.08%, Si: 0.08%, Mg: 0.15%, Li: 0.04%, Ti: 0.005%, and Al and unavoidable impurities: the balance. Fe among the unavoidable impurities had a content of 0.067%, a single non-Fe impurity had a content of 5 0.05%, and non-Fe impurities had a total content of < 0.15%.

[76] The aluminum alloy was manufactured as follows: alloy raw materials conforming to the elementary composition design were melted at 750°C for 3 h to obtain afirst aluminum alloy melt; a 6AB refining agent and a D4 slag forming agent were added to thefirst aluminum alloy melt at an amount of 1 kg/t relative to an amount of the first aluminum alloy melt, and a resulting mixture was subjected to refining at 740°C for 30 min, slagging-off, and then standing for 30 min to obtain a second aluminum alloy melt; the second aluminum alloy melt was introduced into a chute, a grain refining agent Al-3Ti-1B was added to the second aluminum alloy melt, and a resulting mixture was subjected to on-line grain refinement to obtain a third aluminum alloy melt; the third aluminum alloy melt was allowed to flow through a degassing box, a foam ceramic filter plate, and a tubular filter box to obtain a fourth aluminum alloy melt, where a rotor in the degassing box had a rotational speed of 450 rpm, the degassing box had an argon flow rate of 2.05 m3 /h, the foam ceramic filter plate had a porosity of 80 ppi, and a tubular filter for the tubularfilter box had a temperature of 850°C;

[77] the fourth aluminum alloy melt was subjected to casting at 700°C to 730°C to obtain an aluminum alloy ingot;

[78] the aluminum alloy ingot was heated to 530°C at a rate of 4°C/min, held at 530°C for 5 h, and air-cooled to room temperature to obtain a homogenized ingot; then the homogenized ingot was heated to 480°C to 490°C, then extruded at an extrusion speed of 22 m/min, and then subjected to on-line air blast quenching at a cooling rate of 120°C/min to obtain a deformed aluminum alloy, where 2 1050 pure aluminum ingots were used for drainage before extrusion, and the pure aluminum ingots had a temperature of 520°C and were extruded at an extrusion speed of 12 m/min; and the deformed aluminum alloy was heated to 200°C at a rate of 5°C/min and subjected to aging treatment at a holding temperature of 200°C and a holding time of 2 h to obtain the aluminum alloy.

[79] The aluminum alloy obtained in this example was observed under a metallographic microscope, and an obtained metallograph was shown in FIG. 2. It can be seen from FIG. 2 that the aluminum alloy provided by the present disclosure had recrystallized grains above grade 5, which was beneficial for the prominent extrusion performance of the aluminum alloy.

[80] Example 2

[81] In mass percentage, an aluminum alloy with the following elementary composition was designed: Cu: 0.12%, Mn: 0.10%, Si: 0.12%, Mg: 0.20%, Li: 0.05%, Ti: 0.008%, and Al and

12) unavoidable impurities: the balance. Fe among the unavoidable impurities had a content of 0.08%, a single non-Fe impurity had a content of 5 0.05%, and non-Fe impurities had a total content of < 0.15%.

[82] The aluminum alloy was manufactured as follows: alloy raw materials conforming to the elementary composition design were melted at 750°C for 4 h to obtain afirst aluminum alloy melt; a 6AB refining agent and a D4 slag forming agent were added to thefirst aluminum alloy melt at an amount of 0.8 kg/t relative to an amount of thefirst aluminum alloy melt, and a resulting mixture was subjected to refining at 750°C for 18 min, slagging-off, and then standing for 30 min to obtain a second aluminum alloy melt; the second aluminum alloy melt was introduced into a chute, a grain refining agent Al-3Ti-1B was added to the second aluminum alloy melt, and a resulting mixture was subjected to on-line grain refinement to obtain a third aluminum alloy melt; the third aluminum alloy melt was allowed to flow through a degassing box, a foam ceramic filter plate, and a tubular filter box to obtain a fourth aluminum alloy melt, where a rotor in the degassing box had a rotational speed of 450 rpm, the degassing box had an argon flow rate of 2.05 m3 /h, the foam ceramic filter plate had a porosity of 80 ppi, and a tubular filter for the tubularfilter box had a temperature of 850°C;

[83] the fourth aluminum alloy melt was subjected to casting at 700°C to 730°C to obtain an aluminum alloy ingot;

[84] the aluminum alloy ingot was heated to 530°C at a rate of 5°C/min, held at 530°C for 5 h, and air-cooled to room temperature to obtain a homogenized ingot; then the homogenized ingot was heated to 480°C to 490°C, then extruded at an extrusion speed of 22 m/min, and then subjected to on-line air blast quenching at a cooling rate of 120°C/min to obtain a deformed aluminum alloy, where 2 1050 pure aluminum ingots were used for drainage before extrusion, and the pure aluminum ingots had a temperature of 520°C and were extruded at an extrusion speed of 12 m/min; and the deformed aluminum alloy was heated to 200°C at a rate of 5°C/min and subjected to aging treatment at a holding temperature of 200°C and a holding time of 2 h to obtain the aluminum alloy.

[85] Example 3

[86] In mass percentage, an aluminum alloy with the following elementary composition was designed: Cu: 0.10%, Mn: 0.10%, Si: 0.10%, Mg: 0.17%, Li: 0.02%, Ti: 0.005%, and Al and unavoidable impurities: the balance. Fe among the unavoidable impurities had a content of 0.06%, a single non-Fe impurity had a content of < 0.05%, and non-Fe impurities had a total content of < 0.15%.

[87] The aluminum alloy was manufactured as follows: alloy raw materials conforming to the elementary composition design were melted at 740°C for 3 h to obtain a first aluminum alloy melt; a 6AB refining agent and a D4 slag forming agent were added to thefirst aluminum alloy melt at an amount of 1 kg/t relative to an amount of the first aluminum alloy melt, and a resulting mixture was subjected to refining at 760°C for 39 min, slagging-off, and then standing for 30 min to obtain a second aluminum alloy melt; the second aluminum alloy melt was introduced into a chute, a grain refining agent Al-3Ti-1B was added to the second aluminum alloy melt, and a resulting mixture was subjected to on-line grain refinement to obtain a third aluminum alloy melt; the third aluminum alloy melt was allowed to flow through a degassing box, a foam ceramic filter plate, and a tubular filter box to obtain a fourth aluminum alloy melt, where a rotor in the degassing box had a rotational speed of 450 rpm, the degassing box had an argon flow rate of 2.05 m 3 /h, the foam ceramic filter plate had a porosity of 80 ppi, and a tubular filter for the tubularfilter box had a temperature of 850°C;

[88] the fourth aluminum alloy melt was subjected to casting at 700°C to 730°C to obtain an aluminum alloy ingot;

[89] the aluminum alloy ingot was heated to 530°C at a rate of 5°C/min, held at 530°C for 5 h, and air-cooled to room temperature to obtain a homogenized ingot; then the homogenized ingot was heated to 480°C to 490°C, then extruded at an extrusion speed of 22 m/min, and then subjected to on-line air blast quenching at a cooling rate of 120°C/min to obtain a deformed aluminum alloy, where 2 1050 pure aluminum ingots were used for drainage before extrusion, and the pure aluminum ingots had a temperature of 520°C and were extruded at an extrusion speed of 12 m/min; and the deformed aluminum alloy was heated to 200°C at a rate of3C/min and subjected to aging treatment at a holding temperature of 200°C and a holding time of 2 h to obtain the aluminum alloy.

[90] Comparative Example 1

[91] An aluminum alloy in this example had the same elementary composition as that in Example 3.

[92] The aluminum alloy was obtained by a manufacturing process the same as that in Example 3 except that the homogenization treatment was conducted at a holding temperature of 545°C and a holding time of 9 h.

[93] Comparative Example 2

[94] An aluminum alloy in this example had the same elementary composition as that in Example 3.

[95] The aluminum alloy was obtained by a manufacturing process the same as that in Example 3 except that the homogenization treatment was conducted at a holding temperature

1A of 520°C and a holding time of 3 h.

[96] Comparative Example 3

[97] In mass percentage, an aluminum alloy with the following elementary composition was designed: Cu: 0.10%, Mn: 0.12%, Si: 0.10%, Mg: 0.17%, Li: 0.08%, Ti: 0.01%, and Al and unavoidable impurities: the balance. Fe among the unavoidable impurities had a content of 0.10%, a single non-Fe impurity had a content of < 0.05%, and non-Fe impurities had a total content of < 0.15%.

[98] The aluminum alloy was obtained by a manufacturing process the same as that in Example 1.

[99] Under a D65 standard light source, products extruded from the aluminum alloys obtained in Examples 1 to 3 and Comparative Examples 1 to 3 were observed, with a distance of about 600 mm from an examiner's eyes. A schematic diagram of a heat exchanger profile sample in the extrusion test was shown in FIG. 3. The extruded product was a heat exchanger profile with a wall thickness of 0.5 mm, a small-cavity section diameter of 2.5 mm 2 , and a length of 12.3 mm. According to Metallic materials - Tensile testing - Part 1: Method of Test at Room Temperature (GB T 228.1), the tensile strength was tested using a universal material testing machine for the aluminum alloys obtained in Examples 1 to 3 and Comparative Examples 1 to 3, and test results were shown in Table 1.

[100] Table 1 Performance test results of the aluminum alloys obtained in Examples 1 to 3 and Comparative Examples 1 to 3 Extrusion production status Extruded product quality

Whether the Continuous extrusion Tensile aluminum alloy can Appearance production status of 50 ingots strength/MPa be extruded out

A profile has a complete Continuous production is Example 1 Extrusion is possible structure, a smooth surface, 152 possible and no tearing

A profile has a complete Continuous production is Example 2 Extrusion is possible structure, a smooth surface, 170 possible and no tearing

A profile has a complete Continuous production is Example 3 Extrusion is possible structure, a smooth surface, 159 possible and no tearing

Comparative Extrusion is possible Continuous production is A profile has a complete 139

1 r

Example 1 possible structure, a smooth surface,

and no tearing

Comparative Extrusion is

Example 2 impossible

When the 10 th ingot is Comparative A profile has a rough surface Extrusion is possible produced, a surface of the 153 Example 3 and many scratches ingot is scratched and torn

[101] Note: "/" in Table 1 means that, since extrusion is impossible, the aluminum alloy does not have the basic extrusion performance, and the subsequent extrusion production test and extruded product test are not conducted.

[102] It can be seen from Table 1 that the aluminum alloy provided by the present disclosure has prominent extrudability, prominent continuous extrusion production performance, and a tensile strength as high as 152 MPa to 170 MPa.

[103] The above descriptions are merely preferred implementations of the present disclosure. It should be noted that a person of ordinary skill in the art may further make several improvements and modifications without departing from the principle of the present disclosure, but such improvements and modifications should be deemed as falling within the protection scope of the present disclosure.

Claims

WHAT IS CLAIMED IS:

1. An aluminum alloy, comprising the following elements, in mass percentage: Cu: 0.08% to 0.12%, Mn: 0.07% to 0.10%, Si: 0.08% to 0.12%, Mg: 0.15% to 0.20%, Li: 0.02% to 0.06%, Ti: 0.005% to 0.008%, and Al and unavoidable impurities: the balance; wherein 0.12 wt.% < Li + Mn < 0.15 wt.%.

2. The aluminum alloy according to claim 1, wherein the unavoidable impurities comprise Fe and non-Fe impurities; and in mass percentage, Fe has a content of < 0.08%, a single element among the non-Fe impurities has a content of < 0.05%, and the non-Fe impurities have a total content of 0.15%; wherein the aluminum alloy has a tensile strength of 150 MPa to 170 MPa; wherein the aluminum alloy can be extruded into a profile with a limit wall thickness of 0.5 mm; and when the aluminum alloy is extruded into a small-cavity profile, a single small cavity has a limit section area of 2 mm2 and there are 5 to 50 small cavities.

3. A manufacturing process of the aluminum alloy according to any one of claims 1 to 2, comprising the following steps: subjecting alloy raw materials to smelting and casting in sequence to obtain an aluminum alloy ingot, wherein the smelting comprises melting, refining, on-line grain refinement, and on-line degassing and filtration that are conducted in sequence; and subjecting the aluminum alloy ingot to homogenization treatment, deformation treatment, quenching, and aging treatment in sequence to obtain the aluminum alloy.

4. The manufacturing process according to claim 3, wherein the melting is conducted at 740°C to 760°C; the refining is conducted at 730°C to 780°C for 10 min to 40 min; the grain refinement is conducted at 710°C to 750°C; and the on-line degassing and filtration comprises degassing box filtration, foam ceramic filter plate filtration, and tubular filter box filtration that are conducted in sequence; wherein the homogenization treatment is conducted at a holding temperature of 520°C to 540°C and a holding time of 4 h to 8 h; wherein the deformation treatment is conducted at 450°C to 500°C; wherein the aging treatment is conducted at a holding temperature of 200°C to 210°C and

1-7 a holding time of 1 h to 3 h.

5. Use of the aluminum alloy according to any one of claims 1 to 2 or an aluminum alloy manufactured by the manufacturing process according to any one of claims 3 to 4 as a thin-walled small-cavity structure profile in heat exchangers.

1Q

－1/1－ 03 Jun 2021

DRAWINGS 2021103058

FIG. 1

FIG. 2

FIG. 3