6XXX series aluminum alloy with high strength and toughness and corrosion resistance and aging process of 6XXX series aluminum alloy

Abstract

The invention relates to a high-toughness corrosion-resistant 6XXX series aluminum alloy and an aging process thereof, and relates to the technical field of aluminum alloy materials, and alloy components of the high-toughness corrosion-resistant 6XXX series aluminum alloy comprise conventional alloy elements and microalloying elements; the conventional alloy elements comprise Si, Mg and Cu, and the microalloying element is selected from one or more of Ti, Fe, Mn and Zn. By adding the Cu element, a multi-element strengthening effect is formed, and high strength is obtained. And a short-time pre-aging process is carried out before artificial aging, and then peak aging is carried out, so that the characteristics of a continuous precipitated phase of a grain boundary can be destroyed, and excellent intergranular corrosion resistance is achieved while the obdurability of the aluminum alloy is improved.

Description

Technical Field

[0001] The present application relates to the technical field of aluminum alloy materials, and in particular to a high-strength, tough, and corrosion-resistant 6XXX series aluminum alloy and an aging process thereof. Background Art

[0002] At present, 6XXX series aluminum alloys are aluminum-magnesium-silicon alloys with good corrosion resistance, medium strength, excellent machinability and good weldability, and the strength can be further improved by heat treatment. Common grades such as 6061, 6063 and 6082 are widely used in construction, transportation, aerospace and industrial products such as door and window frames, automotive parts and medium and low load structural parts.

[0003] With the advancement of the new energy vehicle strategy, the temperature control of power batteries is particularly important. Liquid cooling technology has become the mainstream cooling method for battery systems due to its high efficiency and reliability, and liquid cooling plates are key components. Liquid cooling plates need to work at high temperatures and high flow rates, so they are required to have good waterproof and corrosion resistance. Aluminum alloys have become commonly used materials due to their low density, good thermal conductivity and strength. Compared with 3XXX series aluminum alloys, 6XXX series Al-Mg-Si-Cu aluminum alloys have higher strength and lightweight advantages and are suitable for liquid cooling plates. Although 6XXX series aluminum alloys have better corrosion resistance than 2XXX series and 7XXX series aluminum alloys, they are the most susceptible to intergranular corrosion. Therefore, how to improve the strength, toughness and intergranular corrosion resistance of 6XXX series aluminum alloys has become a key issue that needs to be solved urgently.

[0004] The existing Chinese patent with publication number CN103774067A discloses a two-stage aging method for improving the intergranular corrosion resistance of 6000 series aluminum alloys. This method improves the corrosion resistance of the aluminum alloy by performing high-temperature pre-aging and low-temperature re-aging after solution treatment and quenching.

[0005] The existing Chinese patent with publication number CN108977739A discloses an aging treatment process for simultaneously improving the strength and stress corrosion resistance of aluminum alloy. The stress corrosion resistance of the alloy is improved by sequentially performing solid solution treatment, low-temperature long-time single-stage aging treatment and double-stage aging treatment on the aluminum alloy.

[0006] The existing Chinese patent with publication number CN115433889B discloses a discontinuous non-isothermal aging treatment process for aluminum alloy, which mainly includes solution quenching, primary non-isothermal aging, quenching, secondary non-isothermal aging, and quenching. A fine intragranular precipitation phase is obtained, which improves the corrosion resistance of the aluminum alloy. Chinese invention patent CN106319402A provides a method for improving strength and intergranular corrosion resistance, which mainly includes 550℃ / 1h solution treatment and water quenching, 180℃ / 2h under-aging, 75% reduction cold rolling, and 100℃ / 48h low-temperature re-aging, to obtain relatively high strength and corrosion resistance.

[0007] The existing Chinese patent with publication number CN106319402A discloses a method for improving strength and intergranular corrosion resistance, which mainly includes 550℃ / 1h solution treatment and water quenching, 180℃ / 2h under-aging, 75% reduction cold rolling, and 100℃ / 48h low-temperature re-aging, thereby achieving relatively high strength and corrosion resistance.

[0008] The existing Chinese patent with publication number CN110951982A discloses a production process for improving the intergranular corrosion resistance of 6 series aluminum alloys. The process adopts a two-stage aging system, specifically including a two-stage aging system of (175-185°C)×(7-9h)+200°C×(3-5h), thereby achieving an optimal combination of tensile strength and intergranular corrosion resistance.

[0009] With regard to the above-mentioned related technologies, it can be seen that the existing technologies mostly regulate the nano-precipitated phase, thereby regulating the corrosion resistance of the aluminum alloy, but to a certain extent, they will inevitably affect the strength of the aluminum alloy. In addition, the existing aging process does not consider the impact of artificial aging. In actual production, after brazing solid solution, the aluminum plate may undergo artificial aging due to site restrictions, which will affect the formation of Mg-Si clusters, and further affect the strength and corrosion resistance of the alloy. Summary of the invention

[0010] The technical problem to be solved by the present invention is to provide a high-strength, toughness and corrosion-resistant 6XXX series aluminum alloy and its aging process. The alloy forms a multi-element strengthening effect by adding Cu elements, and a short-time pre-aging process is performed before artificial aging, so that the strength and toughness of the aluminum alloy are improved while having excellent intergranular corrosion resistance.

[0011] To achieve the above object, the present invention provides the following technical solutions:

[0012] A high-strength, tough, and corrosion-resistant 6XXX series aluminum alloy, the alloy components of which include conventional alloying elements and micro-alloying elements; the conventional alloying elements include Si, Mg, and Cu, and the micro-alloying elements are selected from one or more of Ti, Fe, Mn, and Zn.

[0013] Furthermore, the composition and weight percentage of the high-strength, toughness and corrosion-resistant 6XXX series aluminum alloy are: Si: 0.40-0.50%, Fe: ≤0.30%, Cu: 0.40-0.50%, Mn: 0.30-0.40%, Mg: 0.70-0.90%, Zn: ≤0.50%, Ti: ≤0.50%, the individual content of other elements is 0.05%, the total amount is ≤0.15%, and the balance is Al.

[0014] Furthermore, the deformation structure of the high-strength, toughness and corrosion-resistant 6XXX series aluminum alloy is a layered heterogeneous structure.

[0015] An aging process for any of the above high-strength, tough, and corrosion-resistant 6XXX series aluminum alloys, comprising the following steps:

[0016] The 6XXX series aluminum alloy obtained by smelting is used as the core material and the 4XXX and 3XXX series aluminum alloy skin materials are hot rolled and cold rolled to obtain a multi-layer aluminum alloy foil. The multi-layer aluminum alloy foil with the 6XXX series aluminum alloy as the core material is then annealed and recrystallized, taken out and brazed for solid solution treatment, and then subjected to aging treatment after straightening and shearing.

[0017] Furthermore, the hot rolling temperature is 450-500° C., and the deformation of the high-strength, toughness, and corrosion-resistant 6XXX series aluminum alloy after hot rolling and cold rolling is 90%±5%.

[0018] Furthermore, the annealing and recrystallization treatment system is to heat the multilayer aluminum alloy foil with the rolled 6XXX series aluminum alloy as the core material to 360-400° C. at 60-80° C. / h, then keep the temperature for 3-5 hours, and finally perform water quenching.

[0019] Furthermore, the multilayer aluminum alloy foil with 6XXX series aluminum alloy as the core material is brazed at 35-40°C / min, the temperature is set to 580-620°C, the processing time is 10-20min, and then air quenching is performed.

[0020] Furthermore, the aging treatment process adopts low-temperature pre-aging at 60-80°C for 2 hours, followed by artificial aging at a temperature of 150-200°C for 24 hours, and then peak aging at 170-220°C for 7 hours.

[0021] In summary, the present application includes at least one of the following high-strength, toughness, and corrosion-resistant 6XXX series aluminum alloys and their beneficial technical effects of aging process:

[0022] A high-strength, tough, and corrosion-resistant 6XXX series aluminum alloy and its aging process, by adding Cu elements to form a multi-element strengthening effect, to obtain relatively high strength. Then, by performing a short-time pre-aging process before artificial aging, followed by peak aging, the continuous precipitation phase characteristics of the grain boundary can be destroyed, and while improving the strength and toughness of the aluminum alloy, it has excellent intergranular corrosion resistance. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is a cross-sectional view of the intergranular corrosion depth of Example 1 provided mainly in this application;

[0024] Figure 2 This is a cross-sectional view of the intergranular corrosion depth of Example 2 provided mainly in this application;

[0025] Figure 3 This is a cross-sectional view of the intergranular corrosion depth of Example 3 provided mainly in this application;

[0026] Figure 4 This is a cross-sectional view of the intergranular corrosion depth of Comparative Example 1 provided mainly in this application;

[0027] Figure 5 It is a bar graph of intergranular corrosion depth derived from Examples 1-3 and Comparative Example 1 provided in this application;

[0028] Figure 6 It is a mechanical performance diagram of Examples 1-3 and Comparative Example 1 provided mainly in this application;

[0029] Figure 7 This application mainly provides the strength and plasticity results derived from the mechanical performance diagram. DETAILED DESCRIPTION

[0030] In view of the contradiction between strength, plasticity and corrosion resistance of existing aluminum alloy materials mentioned above, the present invention proposes a high-strength, toughness and corrosion-resistant 6XXX series aluminum alloy and its aging process. Figure 1-3 The present invention is further described with specific embodiments so that those skilled in the art can better understand the present invention and implement it, but the embodiments are not intended to limit the present invention.

[0031] Example 1

[0032] The composition and weight percentage of the high-toughness and corrosion-resistant 6XXX series aluminum alloy of this embodiment are silicon (Si): 0.40%, iron (Fe): 0.20%, copper (Cu): 0.41%, manganese (Mn): 0.31%, magnesium (Mg): 0.72%, zinc (Zn): 0.50%, titanium (Ti): 0.50%. The individual content of other elements is ≤0.05%, and the total amount is ≤0.15%. Further, other elements refer to chromium (Cr), vanadium (V), nickel (Ni), zirconium (Zr), boron (B), tin (Sn), calcium (Ca), and other impurity elements that are inevitable in the smelting process. The above impurity elements mainly come from trace impurities in the raw materials or are inevitably introduced in the process. By optimizing the smelting process and selecting high-purity raw materials, the content of these impurities can be effectively controlled to ensure that their individual content is ≤0.05% and the total amount is ≤0.15%. The balance is aluminum (Al).

[0033] The specific processing technology is:

[0034] The 6XXX series aluminum alloy obtained by smelting is used as the core material and the 4XXX and 3XXX series aluminum alloy skin materials are hot rolled and cold rolled to obtain a multi-layer aluminum alloy foil. Specifically, the layer structure of the multi-layer aluminum alloy foil is 4XXX-3XXX-6XXX-3XXX stacked together. Then, the multi-layer aluminum alloy foil with the 6XXX series aluminum alloy as the core material is annealed and recrystallized, taken out and brazed for solid solution treatment, and then aging treatment is performed after straightening and shearing.

[0035] The hot rolling temperature is 500°C, and the deformation of the high-strength, tough, and corrosion-resistant 6XXX series aluminum alloy after hot rolling and cold rolling is 90%.

[0036] Recrystallization treatment after annealing: heating to 380°C at 65°C / h, keeping at this temperature for 5h, and then water quenching.

[0037] The multilayer aluminum alloy foil with 6XXX series aluminum alloy as the core material was brazed at a speed of 35°C / min, the temperature was set to 580°C, the processing time was 20min, and then air quenching was performed.

[0038] For the O-state plate after brazing, a pre-aging treatment was applied at 60°C for 2 hours.

[0039] After that, artificial aging treatment is carried out, the temperature of artificial aging is 170° and the treatment time is 24h.

[0040] After that, peak aging treatment was carried out at a temperature of 170°C for 7 hours.

[0041] The surface quality, mechanical properties and corrosion resistance of the aged aluminum alloy plates were tested.

[0042] Example 2

[0043] The composition and weight percentage of the high-toughness and corrosion-resistant 6XXX series aluminum alloy in this embodiment are Si: 0.40%, Fe: 0.25%, Cu: 0.45%, Mn: 0.31%, Mg: 0.72%, Zn: 0.50%, Ti: 0.50%. The specific heat treatment process is:

[0044] Recrystallization treatment after annealing: heating to 380°C at 65°C / h, keeping at this temperature for 5h, and then water quenching.

[0045] The multilayer aluminum alloy foil with 6XXX series aluminum alloy as the core material was brazed at a speed of 35°C / min, the temperature was set to 580°C, the processing time was 20min, and then air quenching was performed.

[0046] For the O-state plate after brazing, a pre-aging treatment was applied at 60°C for 2 hours.

[0047] After that, artificial aging treatment is carried out, the temperature of artificial aging is 170° and the treatment time is 24h.

[0048] After that, peak aging treatment was carried out at a temperature of 170°C for 7 hours.

[0049] The surface quality, mechanical properties and corrosion resistance of the aged aluminum alloy plates were tested.

[0050] Example 3

[0051] The composition and weight percentage of the high-toughness and corrosion-resistant 6XXX series aluminum alloy in this embodiment are Si: 0.40%, Fe: 0.20%, Cu: 0.41%, Mn: 0.31%, Mg: 0.72%, Zn: 0.50%, Ti: 0.50%. The specific heat treatment process is:

[0052] Recrystallization treatment after annealing: heating to 380°C at 65°C / h, keeping at this temperature for 5h, and then water quenching.

[0053] The multilayer aluminum alloy foil with 6XXX series aluminum alloy as the core material was brazed at a speed of 35°C / min, the temperature was set to 580°C, the processing time was 20min, and then air quenching was performed.

[0054] For the O-state plate after brazing, a pre-aging treatment was applied at 70°C for 2 hours.

[0055] After that, artificial aging treatment is carried out, the temperature of artificial aging is 170° and the treatment time is 24h.

[0056] After that, peak aging treatment was carried out at a temperature of 165°C for 7 hours.

[0057] The surface quality, mechanical properties and corrosion resistance of the aged aluminum alloy plates were tested.

[0058] Comparative Example 1

[0059] The alloy composition and weight percentage of this embodiment are Si: 0.40%, Fe: 0.20%, Cu: 0.41%, Mn: 0.31%, Mg: 0.72%, Zn: 0.50%, Ti: 0.50%. The specific heat treatment process is:

[0060] Recrystallization treatment after annealing: heating to 380°C at 65°C / h, keeping at this temperature for 5h, and then water quenching.

[0061] The multilayer aluminum alloy foil with 6XXX series aluminum alloy as the core material was brazed at a speed of 35°C / min, the temperature was set to 580°C, the processing time was 20min, and then air quenching was performed.

[0062] The O-state plate after brazing was subjected to artificial aging treatment, the artificial aging temperature was 170°, and the treatment time was 24h.

[0063] After that, peak aging treatment was carried out at a temperature of 170°C for 7 hours.

[0064] The surface quality, mechanical properties and corrosion resistance of the aged aluminum alloy plates were tested.

[0065] The 6XXX aluminum alloys of Examples 1-3 and Comparative Example 1 were tested for performance, and the tensile properties were in accordance with the national standard (GB / T228.1-2021), and the intergranular corrosion test was in accordance with the national standard (GB / T26491-2011). It can be seen that the 6XXX aluminum alloys of the present invention can reach a yield strength of 230-240 MPa, an elongation after fracture of 15-17%, and a mass loss of 16-18% after the intergranular corrosion test after the aging process. The yield strength of the comparative example can reach 220-230 MPa, an elongation after fracture of 15-17%, and a mass loss of 19-21% after the intergranular corrosion test.

[0066] The above results show that the alloy treated by the 6XXX series aluminum alloy and the aging process thereof mentioned in the present invention forms a multi-element strengthening effect by adding the Cu element, and obtains a higher strength. When the alloy strength is improved, a short-time pre-aging process is performed before artificial aging, and then peak aging is performed, which can destroy the continuous precipitation phase characteristics of the grain boundary, and while improving the toughness of the aluminum alloy, it has excellent intergranular corrosion resistance, and the intergranular corrosion resistance of the alloy is also significantly improved. Therefore, by using the 6XXX series aluminum alloy and the aging process of the present invention, an aluminum alloy with good mechanical properties and corrosion resistance can be obtained.

[0067] Figure 5 The intergranular corrosion depth bar graphs derived from Examples 1-3 and Comparative Example 1 of the present application, and in the attached figure, IGCDepth (Intergranular Corrosion Depth) refers to the intergranular corrosion depth, that is, the depth of corrosion extending along the grain boundary of the material (i.e., the area between the grains). The unit of the intergranular corrosion depth is micrometer.

[0068] Figure 6 It is the mechanical performance diagram of Examples 1-3 and Comparative Example 1 provided in this application. Figure 6 The horizontal axis in is engineering strain (usually represented by the symbol ε), which is a measure of the change in relative shape or length of a material when it is subjected to force or deformation. It is calculated by measuring the change between the original length of the material and the length after deformation.

[0069] The calculation formula is: Where: ΔL is the change in length of the material before and after deformation (i.e. the length after deformation minus the original length): L 0 is the original length of the material.

[0070] Figure 6 The vertical axis is engineering stress, usually represented by the symbol σ, which is a measure of the stress state of a material under external force. It is calculated by the ratio of the external force on the material to the original cross-sectional area.

[0071] The calculation formula is: Where: F is the external force applied to the material (in Newton, N); A 0 is the original cross-sectional area of ​​the material (in square millimeters, mm 2 ).

[0072] Figure 7 It is the strength and plasticity results derived from the mechanical properties diagram. The abscissa represents tensile strength / MPa, yield strength / MPa and elongation / %.

[0073] The above are all preferred embodiments of the present application, and the protection scope of the present application is not limited thereto. Therefore, any equivalent changes made according to the structure, shape, and principle of the present application should be included in the protection scope of the present application.

Claims

1. A high-strength, tough, and corrosion-resistant 6XXX series aluminum alloy, characterized in that: The alloy components of the high-strength, toughness and corrosion-resistant 6XXX series aluminum alloy include conventional alloying elements and micro-alloying elements; the conventional alloying elements include Si, Mg and Cu, and the micro-alloying elements are selected from one or more of Ti, Fe, Mn and Zn.

2. A high-strength, tough, and corrosion-resistant 6XXX series aluminum alloy according to claim 1, characterized in that: The high-strength, toughness and corrosion-resistant 6XXX series aluminum alloy has the following components and weight percentages: Si: 0.40-0.50%, Fe: ≤0.30%, Cu: 0.40-0.50%, Mn: 0.30-0.40%, Mg: 0.70-0.90%, Zn: ≤0.50%, Ti: ≤0.50%, the individual content of other elements is 0.05%, the total content is ≤0.15%, and the balance is Al.

3. The high-toughness and corrosion-resistant 6XXX series aluminum alloy according to claim 1, characterized in that: The high-strength, toughness and corrosion-resistant 6XXX series aluminum alloy deformation structure is a layered heterogeneous structure.

4. An aging process for the high-toughness and corrosion-resistant 6XXX series aluminum alloy according to any one of claims 1 to 3, characterized in that: The following steps are involved: The 6XXX series aluminum alloy obtained by smelting is used as the core material and the 4XXX and 3XXX series aluminum alloy skin materials are hot rolled and cold rolled to obtain a multi-layer aluminum alloy foil. The multi-layer aluminum alloy foil with the 6XXX series aluminum alloy as the core material is then annealed and recrystallized, taken out and brazed for solid solution treatment, and then subjected to aging treatment after straightening and shearing.

5. The aging process according to claim 4, characterized in that: The hot rolling temperature is 450-500° C., and the deformation of the high-strength, tough, and corrosion-resistant 6XXX series aluminum alloy after hot rolling and cold rolling is 90%±5%.

6. The aging process according to claim 4, characterized in that: The annealing and recrystallization treatment system is to heat the multi-layer aluminum alloy foil with the rolled 6XXX series aluminum alloy as the core material to 360-400° C. at 60-80° C. / h, then keep the temperature for 3-5 hours, and finally perform water quenching treatment.

7. The aging process according to claim 4, characterized in that: The multi-layer aluminum alloy foil material with 6XXX series aluminum alloy as the core material is brazed at 35-40°C / min, the temperature is set to 580-620°C, the processing time is 10-20min, and then air quenching is performed.

8. The aging process according to claim 4, characterized in that: The aging treatment process adopts low-temperature pre-aging at 60-80°C for 2 hours, followed by artificial aging at a temperature of 150-200°C for 24 hours, and then peak aging at 170-220°C for 7 hours.

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