High-strength 6-series aluminum alloy for automobile anti-collision beam and preparation method of high-strength 6-series aluminum alloy

Abstract

The invention discloses a high-strength 6-series aluminum alloy for an automobile anti-collision beam, which comprises the following chemical components in percentage by mass: 0.80 to 1.20 percent of Si, 0.70 to 1.15 percent of Mg, 0.15 to 0.80 percent of Cu, 0.10 to 0.50 percent of Mn, 0.05 to 0.20 percent of Cr, less than or equal to 0.1 percent of Ti, less than or equal to 0.15 percent of V, less than or equal to 0.18 percent of Fe and the balance of Al and inevitable impurity elements. The content of the impurity elements is smaller than or equal to 0.15%; wherein Mg / Si is larger than or equal to 0.8 and smaller than or equal to 1.2, Si-1.33 Mg is larger than or equal to-0.2 and smaller than or equal to 0, Mg-1. 02 Si-0.3 Cu is larger than or equal to-0.4 and smaller than or equal to-0.2, and Ti / V is larger than or equal to 1.5 and smaller than or equal The aluminum alloy prepared from the chemical components provided by the invention is very excellent in aging state, tensile strength, yield strength, ductility and tensile strength reduction after 30 days.

Description

Technical Field

[0001] The present invention relates to the field of aluminum alloys, and more specifically, to a high-strength 6-series aluminum alloy for automotive bumper beams and a preparation method thereof. Background Art

[0002] As the most abundant metallic element on Earth, aluminum alloy has a wide range of applications in lightweight transportation due to its low density and recyclability. Cast aluminum alloys are mainly used in components such as wheel hubs and engines; 2-series aluminum alloys are mainly used in automotive body panels, etc.; 6-series aluminum alloys are mostly used in body panels and frame materials. As the main components for passive safety protection of automobiles, energy-absorbing boxes and bumper beams mainly absorb external energy through deformation or conduct external impacts to the vehicle body during collisions, thereby protecting the safety of vehicle occupants. Generally, energy-absorbing boxes are made of 6-series aluminum alloys such as 6063 and 6008, and the aluminum alloys used for bumper beams are 7-series aluminum alloys such as 7003 and 7005, which have relatively high strength. Energy-absorbing boxes and bumper beams are generally connected by welding and bolts. The weldability of 7-series aluminum alloys is poor. When the bumper beam system is recycled, 6-series aluminum alloys and 7-series aluminum alloys need to be recycled separately. However, the existing 6-series aluminum alloys have problems such as poor performance in terms of aging state, tensile strength, yield strength, elongation, and tensile strength decline after 30 days.

[0003] In summary, after extensive searches by the applicant, there is at least a problem in the prior art that the existing 6-series aluminum alloys have poor performance in terms of aging state, tensile strength, yield strength, elongation, and tensile strength decline after 30 days. Therefore, it is necessary to develop or improve a high-strength 6-series aluminum alloy for automotive bumper beams and a preparation method thereof. Summary of the Invention

[0004] Based on this, in order to solve the problem that the existing 6-series aluminum alloys have poor performance in terms of aging state, tensile strength, yield strength, elongation, and tensile strength decline after 30 days, the present invention provides a high-strength 6-series aluminum alloy for automotive bumper beams and a preparation method thereof. The specific technical solutions are as follows:

[0005] A high-strength 6-series aluminum alloy for automotive bumper beams, calculated as a percentage of the total mass of the aluminum alloy, consists of the following chemical components:

[0006] Si: 0.80 - 1.20%, Mg: 0.70 - 1.15%, Cu: 0.15 - 0.80%, Mn: 0.10 - 0.50%, Cr: 0.05 - 0.20%, Ti: ≤0.1%, V: ≤0.15%, Fe: ≤0.18%, and the balance is Al and inevitable impurity elements;

[0007] The content of the impurity elements ≤0.15%;

[0008] Among them, 0.8 ≤ Mg / Si ≤ 1.2, -0.2 ≤ Si - 1.33Mg ≤ 0, -0.4 ≤ Mg - 1.02Si - 0.3Cu ≤ -0.2, 1.5 ≤ Ti / V ≤ 2.5.

[0009] This technical solution also provides a preparation method of a high-strength 6-series aluminum alloy for an automobile anti-collision beam, which includes the following steps:

[0010] Prepare raw materials according to the chemical composition, then add them into a melting furnace to melt, refine, degas and filter the melt, and then cast the liquid aluminum alloy into an aluminum alloy ingot.

[0011] Place the aluminum alloy ingot in a homogenizing furnace for homogenization treatment to obtain a homogenized aluminum alloy ingot.

[0012] Cool the homogenized aluminum alloy ingot to obtain a cooled aluminum alloy ingot.

[0013] Extrude and form the cooled aluminum alloy ingot to obtain an aluminum alloy profile.

[0014] Quench the aluminum alloy profile to obtain quenched aluminum alloy.

[0015] Age the quenched aluminum alloy to obtain the high-strength 6-series aluminum alloy for the automobile anti-collision beam.

[0016] The chemical composition is as follows: based on the total mass of the aluminum alloy as 100%, Si: 0.80 - 1.20%, Mg: 0.70 - 1.15%, Cu: 0.15 - 0.80%, Mn: 0.10 - 0.50%, Cr: 0.05 - 0.20%, Ti: ≤0.1%, V: ≤0.15%, Fe: ≤0.18%, and the balance is Al and unavoidable impurity elements.

[0017] The content of the impurity elements ≤0.15%; among them, 0.8 ≤ Mg / Si ≤ 1.2, -0.2 ≤ Si - 1.33Mg ≤ 0, -0.4 ≤ Mg - 1.02Si - 0.3Cu ≤ -0.2, 1.5 ≤ Ti / V ≤ 2.5.

[0018] Furthermore, the number of times of refining is 2 times.

[0019] Furthermore, the gas used for degassing is high-purity argon.

[0020] Furthermore, the filtration adopts double-stage filtration.

[0021] Furthermore, the homogenization treatment includes the following steps:

[0022] Place the aluminum alloy cast rod in a homogenizing furnace, set the temperature to 500 - 560 °C, and hold for 8 - 16 h to obtain the homogenized aluminum alloy cast rod.

[0023] Further, the cooling treatment includes the following steps:

[0024] Perform air mist cooling on the homogenized aluminum alloy cast rod, and then place it in the air to cool to room temperature to obtain the cooled aluminum alloy cast rod.

[0025] Further, the extrusion forming treatment includes the following steps:

[0026] Preheat the cooled aluminum alloy cast rod to 480 - 500 °C, and then perform extrusion production to obtain the aluminum alloy profile.

[0027] Further, the quenching treatment includes the following steps:

[0028] Cool the aluminum alloy profile in a water mist manner, and then cool it in a water cooling manner to obtain the quenched aluminum alloy.

[0029] Further, the aging treatment includes the following steps:

[0030] Heat the quenched aluminum alloy to 160 - 180 °C, and hold for 6 - 16 h to obtain the high-strength 6-series aluminum alloy for automotive anti-collision beams.

[0031] The aluminum alloy prepared from the chemical components provided by the above technical solution has excellent properties in terms of aging state, tensile strength, yield strength, elongation, and tensile strength reduction after 30 days; specifically, Al-Mg-Si is a heat-treatable aluminum alloy. Through certain heat treatments, strengthening phases such as β and β" can be obtained. Among them, β" is the main strengthening phase during peak aging of the alloy. When -0.2 ≤ Si - 1.33Mg ≤ 0, it can promote the precipitation of β" inside the alloy. However, when the Si content exceeds a certain amount, it will precipitate in the form of a single substance, and the presence of elemental silicon will affect the strength and toughness of the alloy; adding a certain amount of Mn to the alloy with excess Si, Mn and Si form the AlMnSi secondary phase, which can consume part of the excess Si. Moreover, as the Mn content increases, it promotes the transformation of acicular β-AlMnSi to granular α-AlMnSi, which can improve the impact toughness and bending properties of the alloy. In the present invention, the contents of Mg, Si, and Mn need to follow a certain strict constraint relationship to ensure the effective formation of dispersed strengthening phases and coarse secondary phases inside the alloy; further, the solubility of Mg2Si in the aluminum matrix decreases with the decrease of temperature. At a temperature of 595 °C, the maximum solubility in the aluminum matrix is 1.85, while at a temperature of 200 °C, the solubility is only 0.25%; Cu and Mg can form the AlCuMg phase, which can increase the solubility of Mg in the alloy to a certain extent; in the initial stage of aging, the Cu element combines with vacancies and hinders the precipitation of clusters, which can alleviate the adverse effect of strength reduction caused by the parking effect of the alloy; furthermore, the Ti element and the V element can interact with each other to make up for the spatial defects of the aluminum alloy; therefore, the contents of Mg, Si, Cu, Ti, and V need to follow a certain strict constraint relationship, specifically 0.8 ≤ Mg / Si ≤ 1.2, -0.2 ≤ Si - 1.33Mg ≤ 0, -0.4 ≤ Mg - 1.02Si - 0.3Cu ≤ -0.2, 1.5 ≤ Ti / V ≤ 2.5. Detailed implementation manners

[0032] In order to make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail below in conjunction with its embodiments. It should be understood that the specific implementation manners described herein are only used to explain the present invention and do not limit the protection scope of the present invention.

[0033] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the technical field to which the present invention belongs. The terms used in the description of the present invention herein are only for the purpose of describing specific implementation manners and are not intended to limit the present invention. The term "and / or" used herein includes any and all combinations of one or more of the related listed items.

[0034] A high-strength 6-series aluminum alloy for automobile anti-collision beams according to an embodiment of the present invention, based on the total mass of the aluminum alloy as 100%, is composed of the following chemical components:

[0035] Si: 0.80 - 1.20%, Mg: 0.70 - 1.15%, Cu: 0.15 - 0.80%, Mn: 0.10 - 0.50%, Cr: 0.05 - 0.20%, Ti: ≤0.1%, V: ≤0.15%, Fe: ≤0.18%, and the balance is Al and unavoidable impurity elements;

[0036] The content of the impurity elements is ≤0.15%;

[0037] Among them, 0.8 ≤ Mg / Si ≤ 1.2, -0.2 ≤ Si - 1.33Mg ≤ 0, -0.4 ≤

[0038] Mg - 1.02Si - 0.3Cu ≤ -0.2, 1.5 ≤ Ti / V ≤ 2.5.

[0039] Preferably, based on the total mass of the aluminum alloy as 100%, it is composed of the following chemical components:

[0040] Si: 0.80 - 1.20%, Mg: 0.70 - 1.15%, Cu: 0.15 - 0.80%, Mn: 0.10 - 0.50%, Cr: 0.05 - 0.20%, Ti: ≤0.1%, V: ≤0.15%, Fe: ≤0.18%, and the balance is Al and unavoidable impurity elements;

[0041] The content of the impurity elements is ≤0.15%;

[0042] Among them, 0.8 ≤ Mg / Si ≤ 0.9, -0.15 ≤ Si - 1.33Mg ≤ -0.1, -0.4 ≤ Mg - 1.02Si - 0.3Cu ≤ -0.3, 1.5 ≤ Ti / V ≤ 2.

[0043] In one embodiment, the present technical solution provides a preparation method of a high-strength 6-series aluminum alloy for automobile anti-collision beams, which includes the following steps:

[0044] Prepare raw materials according to the chemical composition, then add them into a melting furnace for melting, refine, degas and filter the melt, and then cast the liquid aluminum alloy into an aluminum alloy ingot;

[0045] Place the aluminum alloy ingot in a homogenizing furnace for homogenization treatment to obtain a homogenized aluminum alloy ingot;

[0046] Cool the homogenized aluminum alloy ingot to obtain a cooled aluminum alloy ingot;

[0047] The cooled aluminum alloy cast rod is subjected to extrusion forming to obtain an aluminum alloy profile;

[0048] The aluminum alloy profile is subjected to quenching treatment to obtain quenched aluminum alloy;

[0049] The quenched aluminum alloy is subjected to aging treatment to obtain the high-strength 6-series aluminum alloy for automotive anti-collision beams;

[0050] The chemical composition is as follows: based on the total mass of the aluminum alloy being 100%, Si: 0.80 - 1.20%, Mg: 0.70 - 1.15%, Cu: 0.15 - 0.80%, Mn: 0.10 - 0.50%, Cr: 0.05 - 0.20%, Ti: ≤0.1%, V: ≤0.15%, Fe: ≤0.18%, and the balance being Al and unavoidable impurity elements;

[0051] The content of the impurity elements is ≤0.15%; among them, 0.8 ≤ Mg / Si ≤ 1.2, -0.2 ≤ Si - 1.33Mg ≤ 0, -0.4 ≤ Mg - 1.02Si - 0.3Cu ≤ -0.2, 1.5 ≤ Ti / V ≤ 2.5.

[0052] In one embodiment, the number of refining times is 2 times.

[0053] In one embodiment, the gas used for degassing is high-purity argon.

[0054] In one embodiment, the filtration adopts double-stage filtration.

[0055] In one embodiment, the homogenization treatment includes the following steps:

[0056] The aluminum alloy cast rod is placed in a homogenization furnace, the temperature is set to 500 - 560°C, and it is held for 8 - 16 h to obtain the homogenized aluminum alloy cast rod.

[0057] In one embodiment, the cooling treatment includes the following steps:

[0058] The homogenized aluminum alloy cast rod is subjected to air mist cooling and then cooled in air to room temperature to obtain the cooled aluminum alloy cast rod.

[0059] In one embodiment, the extrusion forming treatment includes the following steps:

[0060] The cooled aluminum alloy cast rod is preheated to 480 - 500°C and then subjected to extrusion production to obtain the aluminum alloy profile.

[0061] In one embodiment, the quenching treatment includes the following steps:

[0062] Cool the aluminum alloy profile by water mist method, and then cool it by water cooling method to obtain the quenched aluminum alloy.

[0063] In one embodiment, the aging treatment includes the following steps:

[0064] Heat the quenched aluminum alloy to 160 - 180 °C and hold for 6 - 16 h to obtain the high-strength 6-series aluminum alloy for automobile anti-collision beam.

[0065] The embodiments of the present invention will be described in detail below in conjunction with specific embodiments.

[0066] Example 1:

[0067] Prepare raw materials according to the chemical composition, then add them into the melting furnace to melt. Refine the melt twice, degas with high-purity argon gas, and filter with double-stage filtration, and then cast the liquid aluminum alloy into an aluminum alloy ingot; place the aluminum alloy ingot in a homogenizing furnace, set the temperature to 560 °C, and hold for 7 h to obtain a homogenized aluminum alloy ingot; cool the homogenized aluminum alloy ingot by air mist cooling, and then cool it in air to room temperature to obtain a cooled aluminum alloy ingot; preheat the cooled aluminum alloy ingot to 490 °C, and then carry out extrusion production to obtain an aluminum alloy profile; cool the aluminum alloy profile by water mist method, and then cool it by water cooling method to obtain a quenched aluminum alloy; heat the quenched aluminum alloy to 170 °C and hold for 12 h to obtain the high-strength 6-series aluminum alloy for automobile anti-collision beam;

[0068] Among them, the chemical composition is: based on the total mass of the aluminum alloy as 100%, Si: 1.06%, Mg: 0.85%, Cu: 0.56%, Mn: 0.39%, Cr: 0.09%, Ti: 0.018%, V: 0.008%, Fe: 0.16%, and the balance is Al and inevitable impurity elements.

[0069] Example 2:

[0070] Prepare raw materials according to the chemical composition, then add them into the melting furnace to melt. Refine the melt twice, degas with high-purity argon gas, and filter with double-stage filtration, and then cast the liquid aluminum alloy into an aluminum alloy ingot; place the aluminum alloy ingot in a homogenizing furnace, set the temperature to 560 °C, and hold for 7 h to obtain a homogenized aluminum alloy ingot; cool the homogenized aluminum alloy ingot by air mist cooling, and then cool it in air to room temperature to obtain a cooled aluminum alloy ingot; preheat the cooled aluminum alloy ingot to 490 °C, and then carry out extrusion production to obtain an aluminum alloy profile; cool the aluminum alloy profile by water mist method, and then cool it by water cooling method to obtain a quenched aluminum alloy; heat the quenched aluminum alloy to 170 °C and hold for 12 h to obtain the high-strength 6-series aluminum alloy for automobile anti-collision beam;

[0071] Among them, the chemical composition is as follows: based on the total mass of the aluminum alloy as 100%, Si: 1.13%, Mg: 0.93%, Cu: 0.57%, Mn: 0.37%, Cr: 0.1%, Ti: 0.02%, V: 0.012%, Fe: 0.16%, and the balance is Al and inevitable impurity elements.

[0072] Example 3:

[0073] Prepare raw materials according to the chemical composition, then add them into a melting furnace to melt. Refine the melt twice, degas it with high-purity argon, and filter it using double-stage filtration. Then cast the liquid aluminum alloy into an aluminum alloy ingot; place the aluminum alloy ingot in a homogenizing furnace, set the temperature to 560 °C, and hold for 7 h to obtain a homogenized aluminum alloy ingot; subject the homogenized aluminum alloy ingot to air mist cooling, and then cool it in air to room temperature to obtain a cooled aluminum alloy ingot; preheat the cooled aluminum alloy ingot to 490 °C, and then carry out extrusion production to obtain an aluminum alloy profile; cool the aluminum alloy profile by water mist method and then by water cooling method to obtain a quenched aluminum alloy; heat the quenched aluminum alloy to 170 °C and hold for 12 h to obtain a high-strength 6-series aluminum alloy for automotive bumper beams;

[0074] Among them, the chemical composition is as follows: based on the total mass of the aluminum alloy as 100%, Si: 1.12%, Mg: 0.97%, Cu: 0.42%, Mn: 0.28%, Cr: 0.12%, Ti: 0.021%, V: 0.013%, Fe: 0.18%, and the balance is Al and inevitable impurity elements.

[0075] Comparative Example 1:

[0076] Prepare raw materials according to the chemical composition, then add them into a melting furnace to melt. Refine the melt twice, degas it with high-purity argon, and filter it using double-stage filtration. Then cast the liquid aluminum alloy into an aluminum alloy ingot; place the aluminum alloy ingot in a homogenizing furnace, set the temperature to 560 °C, and hold for 7 h to obtain a homogenized aluminum alloy ingot; subject the homogenized aluminum alloy ingot to air mist cooling, and then cool it in air to room temperature to obtain a cooled aluminum alloy ingot; preheat the cooled aluminum alloy ingot to 490 °C, and then carry out extrusion production to obtain an aluminum alloy profile; cool the aluminum alloy profile by water mist method and then by water cooling method to obtain a quenched aluminum alloy; heat the quenched aluminum alloy to 170 °C and hold for 12 h to obtain an aluminum alloy;

[0077] Among them, the chemical composition is as follows: based on the total mass of the aluminum alloy as 100%, Si: 1.15%, Mg: 1.05%, Cu: 0.44%, Mn: 0.42%, Cr: 0.19%, Ti: 0.022%, V: 0.012%, Fe: 0.17%, and the balance is Al and inevitable impurity elements.

[0078] Comparative Example 2:

[0079] Prepare raw materials according to the chemical composition, then add them into a melting furnace for melting. Refine the melt twice, degas it with high-purity argon, and filter it using double-stage filtration. Then cast the liquid aluminum alloy into an aluminum alloy ingot; place the aluminum alloy ingot in a homogenizing furnace, set the temperature to 560 °C, and hold for 7 h to obtain a homogenized aluminum alloy ingot; subject the homogenized aluminum alloy ingot to air mist cooling, and then cool it in air to room temperature to obtain a cooled aluminum alloy ingot; preheat the cooled aluminum alloy ingot to 490 °C, and then carry out extrusion production to obtain an aluminum alloy profile; cool the aluminum alloy profile by water mist method and then by water cooling method to obtain a quenched aluminum alloy; heat the quenched aluminum alloy to 170 °C and hold for 12 h to obtain an aluminum alloy;

[0080] Among them, the chemical composition is: based on the total mass of the aluminum alloy as 100%, Si: 0.96%, Mg: 0.94%, Cu: 0.22%, Mn: 0.43%, Cr: 0.09%, Ti: 0.027%, V: 0.015%, Fe: 0.15%, and the balance is Al and inevitable impurity elements.

[0081] Comparative Example 3:

[0082] Prepare raw materials according to the chemical composition, then add them into a melting furnace for melting. Refine the melt twice, degas it with high-purity argon, and filter it using double-stage filtration. Then cast the liquid aluminum alloy into an aluminum alloy ingot; place the aluminum alloy ingot in a homogenizing furnace, set the temperature to 560 °C, and hold for 7 h to obtain a homogenized aluminum alloy ingot; subject the homogenized aluminum alloy ingot to air mist cooling, and then cool it in air to room temperature to obtain a cooled aluminum alloy ingot; preheat the cooled aluminum alloy ingot to 490 °C, and then carry out extrusion production to obtain an aluminum alloy profile; cool the aluminum alloy profile by water mist method and then by water cooling method to obtain a quenched aluminum alloy; heat the quenched aluminum alloy to 170 °C and hold for 12 h to obtain an aluminum alloy;

[0083] Among them, the chemical composition is: based on the total mass of the aluminum alloy as 100%, Si: 0.87%, Mg: 1.13%, Cu: 0.51%, Mn: 0.36%, Cr: 0.11%, Ti: 0.017%, V: 0.011%, Fe: 0.18%, and the balance is Al and inevitable impurity elements.

[0084] Comparative Example 4:

[0085] Prepare raw materials according to the chemical composition, then add them into the melting furnace for melting. Refine the melt twice, degas it with high-purity argon, and filter it by double-stage filtration. Then cast the liquid aluminum alloy into aluminum alloy ingots; place the aluminum alloy ingots in a homogenizing furnace, set the temperature to 560 °C, and keep it warm for 7 h to obtain homogenized aluminum alloy ingots; cool the homogenized aluminum alloy ingots by air fog cooling, and then cool them in the air to room temperature to obtain cooled aluminum alloy ingots; preheat the cooled aluminum alloy ingots to 490 °C, and then carry out extrusion production to obtain aluminum alloy profiles; cool the aluminum alloy profiles by water mist cooling, and then cool them by water cooling to obtain quenched aluminum alloy; heat the quenched aluminum alloy to 170 °C and keep it warm for 12 h to obtain aluminum alloy;

[0086] Among them, the chemical composition is: based on the total mass of the aluminum alloy as 100%, Si: 1.04%, Mg: 0.70%, Cu: 0.15%, Mn: 0.39%, Cr: 0.13%, Ti: 0.021%, V: 0.009%, Fe: 0.15%, and the balance is Al and inevitable impurity elements.

[0087] Comparative Example 5:

[0088] Prepare raw materials according to the chemical composition, then add them into the melting furnace for melting. Refine the melt twice, degas it with high-purity argon, and filter it by double-stage filtration. Then cast the liquid aluminum alloy into aluminum alloy ingots; place the aluminum alloy ingots in a homogenizing furnace, set the temperature to 560 °C, and keep it warm for 7 h to obtain homogenized aluminum alloy ingots; cool the homogenized aluminum alloy ingots by air fog cooling, and then cool them in the air to room temperature to obtain cooled aluminum alloy ingots; preheat the cooled aluminum alloy ingots to 490 °C, and then carry out extrusion production to obtain aluminum alloy profiles; cool the aluminum alloy profiles by water mist cooling, and then cool them by water cooling to obtain quenched aluminum alloy; heat the quenched aluminum alloy to 170 °C and keep it warm for 12 h to obtain aluminum alloy;

[0089] Among them, the chemical composition is: based on the total mass of the aluminum alloy as 100%, Si: 1.07%, Mg: 0.93%, Cu: 0.62%, Mn: 0.42%, Cr: 0.13%, Ti: 0.021%, V: 0.007%, Fe: 0.17%, and the balance is Al and inevitable impurity elements.

[0090] Comparative Example 6:

[0091] Prepare raw materials according to the chemical composition, then add them into the melting furnace for melting. Refine the melt twice, degas it with high-purity argon, and filter it using double-stage filtration. Then cast the liquid aluminum alloy into aluminum alloy ingots; place the aluminum alloy ingots in a homogenizing furnace, set the temperature at 560 °C, and hold for 7 hours to obtain homogenized aluminum alloy ingots; cool the homogenized aluminum alloy ingots by air fog cooling, and then cool them in the air to room temperature to obtain cooled aluminum alloy ingots; preheat the cooled aluminum alloy ingots to 490 °C, and then carry out extrusion production to obtain aluminum alloy profiles; cool the aluminum alloy profiles by water mist cooling and then by water cooling to obtain quenched aluminum alloy; heat the quenched aluminum alloy to 170 °C and hold for 12 hours to obtain aluminum alloy.

[0092] Among them, the chemical composition is as follows: based on the total mass of the aluminum alloy as 100%, Si: 1.09%, Mg: 0.91%, Cu: 0.53%, Mn: 0.38%, Cr: 0.15%, Ti: 0.007%, V: 0.008%, Fe: 0.16%, and the balance is Al and inevitable impurity elements.

[0093] Test the aging state, tensile strength, yield strength, and elongation of the aluminum alloys obtained in Examples 1 to 3 and Comparative Examples 1 to 6. The test results are shown in Table 1.

[0094] Table 1:

[0095]

[0096] As can be seen from Table 1, for the aluminum alloys prepared from the chemical components provided by the present invention in Examples 1 to 3, their aging state, tensile strength, yield strength, elongation, and the performance of tensile strength decline after 30 days are all excellent; specifically, Al-Mg-Si is a heat-treatable aluminum alloy, and strengthening phases such as β and β" can be obtained through certain heat treatment. Among them, β" is the main strengthening phase during the peak aging of the alloy. When the Si content in the alloy is excessive, that is, Mg / Si < 1.33, it can promote the precipitation of β" inside the alloy. However, when the Si content exceeds a certain amount, it will precipitate in the form of elemental silicon, and the presence of elemental silicon will affect the strength and toughness of the alloy; adding a certain amount of Mn to the alloy with excessive Si, Mn and Si form the AlMnSi secondary phase, which can consume part of the excessive Si, and as the Mn content increases, it promotes the transformation of acicular β-AlMnSi to granular α-AlMnSi, which can improve the impact toughness and bending performance of the alloy. The contents of Mg, Si, and Mn in the present invention need to follow a certain strict constraint relationship to ensure the effective formation of dispersed strengthening phases and coarse secondary phases inside the alloy; further, the solubility of Mg2Si in the aluminum matrix decreases with the decrease of temperature. At a temperature of 595 °C, the maximum solubility in the aluminum matrix is 1.85, while at a temperature of 200 °C, the solubility is only 0.25%; Cu and Mg can form the AlCuMg phase, which can increase the solubility of Mg in the alloy to a certain extent; in the initial stage of aging, the Cu element combines with vacancies and hinders the precipitation of clusters, which can alleviate the adverse effect of strength reduction caused by the parking effect of the alloy; furthermore, the Ti element and the V element can interact with each other to make up for the spatial defects of the aluminum alloy; therefore, the contents of Mg, Si, Cu, Ti, and V need to follow a certain strict constraint relationship, specifically 0.8 ≤ Mg / Si ≤ 1.2, -0.2 ≤ Si - 1.33Mg ≤ 0, -0.4 ≤ Mg - 1.02Si - 0.3Cu ≤ -0.2, 1.5 ≤ Ti / V ≤ 2.5. From the aluminum alloy properties of Examples 1 to 3 and Comparative Examples 1 to 6, it can be seen that this constraint relationship obviously affects the aging state, tensile strength, yield strength, elongation, and the performance of tensile strength decline after 30 days of the aluminum alloy.

[0097] The technical features of the above-described embodiments can be combined arbitrarily. For the sake of brevity of description, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, it should be considered as the scope recorded in this specification.

[0098] The above-described embodiments merely represent several implementation manners of the present invention. The description is relatively specific and detailed, but it should not be construed as a limitation on the scope of the invention patent. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention, several modifications and improvements can still be made, and these all fall within the protection scope of the present invention. Therefore, the protection scope of the present invention patent shall be subject to the appended claims.

Claims

1. A high-strength 6-series aluminum alloy for automobile anti-collision beams, characterized in that: Taking the total mass of aluminum alloy as 100%, it has the following chemical composition composition: Si: 0.80-1.20%, Mg: 0.70-1.15%, Cu: 0.15-0.80%, Mn: 0.10-0.50%, Cr: 0.05-0.20%, Ti: ≤0.1%, V: ≤0.15%, Fe: ≤0.18%, the balance is Al and unavoidable impurity elements; The content of the impurity element is ≤0.15%; Among them, 0.8≤Mg / Si≤1.2, -0.2≤Si-1.33Mg≤0, -0.4≤Mg-1.02Si-0.3Cu≤-0.2, 1.5≤Ti / V≤2.

5.

2. A method for preparing the high-strength 6-series aluminum alloy for automobile anti-collision beams as claimed in claim 1, characterized in that: It includes the following steps: The raw materials are prepared according to the chemical composition, then added into the melting furnace for melting, the melt is refined, degassed and filtered, and then the liquid aluminum alloy is cast into aluminum alloy casting rods; Placing the aluminum alloy cast rod in a homogenizing furnace for homogenization treatment to obtain a homogenized aluminum alloy cast rod; Cooling the homogenized aluminum alloy cast rod to obtain a cooled aluminum alloy cast rod; Extruding the cooled aluminum alloy cast rod to obtain an aluminum alloy profile; The aluminum alloy profile is subjected to quenching treatment to obtain a quenched aluminum alloy; The quenched aluminum alloy is subjected to aging treatment to obtain the high-strength 6 series aluminum alloy for the automobile anti-collision beam; The chemical composition is: based on the total mass of the aluminum alloy, Si: 0.80-1.20%, Mg: 0.70-1.15%, Cu: 0.15-0.80%, Mn: 0.10-0.50%, Cr: 0.05-0.20%, Ti: ≤0.1%, V: ≤0.15%, Fe: ≤0.18%, and the balance is Al and unavoidable impurity elements; The content of the impurity elements is ≤0.15%; among which, 0.8≤Mg / Si≤1.2, -0.2≤Si-1.33Mg≤0, -0.4≤Mg-1.02Si-0.3Cu≤-0.2, 1.5≤Ti / V≤2.

5.

3. The preparation method according to claim 2, characterized in that: The refining was performed twice.

4. The preparation method according to claim 2, characterized in that: The gas used for degassing is high-purity argon.

5. The preparation method according to claim 2, characterized in that: The filtration adopts double-stage filtration.

6. The preparation method according to claim 2, characterized in that: The homogenization process comprises the following steps: The aluminum alloy cast rod is placed in a homogenizing furnace, the temperature is set at 500-560° C., and the temperature is kept at 8-16 hours to obtain the homogenized aluminum alloy cast rod.

7. The preparation method according to claim 2, characterized in that: The cooling process comprises the following steps: The homogenized aluminum alloy cast rod is subjected to wind and mist cooling, and then placed in air to cool to room temperature to obtain the cooled aluminum alloy cast rod.

8. The preparation method according to claim 2, characterized in that: The extrusion molding process comprises the following steps: The cooled aluminum alloy cast rod is preheated to 480-500° C. and then extruded to obtain the aluminum alloy profile.

9. The preparation method according to claim 2, characterized in that: The quenching treatment comprises the following steps: The aluminum alloy profile is cooled by water mist and then by water cooling to obtain the quenched aluminum alloy.

10. The preparation method according to claim 2, characterized in that: The aging treatment comprises the following steps: The quenched aluminum alloy is heated to 160-180° C. and kept warm for 6-16 hours to obtain the high-strength 6 series aluminum alloy for the automobile anti-collision beam.

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