CN109136670B - A kind of 6XXX line aluminium alloy and preparation method thereof - Google Patents

Abstract

The invention provides a 6XXX series aluminum alloy and belongs to the technical field of metal alloys. It is prepared from the following elemental components in weight percentage: Mg 0.8-1.5%, Si 1.5-3.0%, Cu 0.2-0.5%, Mn 0.2-0.5%, Cr 0.1-0.15%, Y 0.15-0.4%, Zr 0.1～0.3%, Sr 0.05～0.15%, Ti 0.01～0.04%, Zn≤0.1%, Fe≤0.5%, single impurity≤0.05%, total impurity≤0.15%, the balance is Al. Yttrium-zirconium refines the as-cast structure of the aluminum alloy, which can strengthen the fine grain; excess Si improves the hardness and strength of the aluminum alloy. It can be seen from the examples that the hardness of the aluminum alloy is 129HBW, the tensile strength is 411MPa, the yield strength is 348MPa, and the elongation is 15%.

Description

A kind of 6XXX series aluminum alloy and preparation method thereof

technical field

The invention relates to the technical field of metal alloys, in particular to a 6XXX series aluminum alloy and a preparation method thereof.

Background technique

6XXX series aluminum alloys are age-strengthened aluminum alloys with low density, medium strength, good welding and formability, etc. They are widely used as structural parts in aerospace, automobiles, high-speed rail, construction and other fields.

It is well known that the properties of 6XXX alloys are affected by the precipitation of the metastable β" phase of the stable phase β phase, while the precipitation of the metastable β" phase of the stable β phase in aluminum alloys is mainly determined by the heat treatment process. Therefore, in order to improve the comprehensive mechanical properties of 6XXX series aluminum alloys, scientific and technical personnel generally focus on the heat treatment steps of aluminum alloys, such as using various heat treatment methods to increase the mechanical strength of aluminum alloys, especially with the help of some precipitation during heat treatment. Precipitation hardening caused by nano-scale precipitated phase is a research hotspot in recent years.

In the prior art, there is no research on improving the properties of aluminum alloys by adding other metal elements and matching heat treatment to 6XXX series aluminum alloys.

Contents of the invention

In view of this, the object of the present invention is to provide a 6XXX series aluminum alloy and a preparation method thereof. In the present invention, elements silicon, yttrium and zirconium are added to the raw material of the aluminum alloy, and the joint action of the three improves the comprehensive performance of the aluminum alloy.

In order to achieve the above-mentioned purpose of the invention, the present invention provides the following technical solutions:

The invention provides a 6XXX series aluminum alloy, which is prepared from the following element components in weight percent: Mg 0.8-1.5%, Si 1.5-3.0%, Cu 0.2-0.5%, Mn 0.2-0.5%, Cr 0.1～0.15%, Y0.15～0.4%, Zr 0.1～0.3%, Sr 0.05～0.15%, Ti 0.01～0.04%, Zn≤0.1%, Fe≤0.5%, single impurity≤0.05%, total impurity≤0.15 %, the balance is Al.

Preferably, it is prepared from the following elemental components in weight percentage: 0.92% Mg, 2.0% Si, 0.3% Cu, 0.4% Mn, 0.1% Cr, 0.25% Y, 0.15% Zr, 0.10% Sr, Ti 0.02%, Zn ≤ 0.1%, Fe ≤ 0.2%, single impurity ≤ 0.05%, total impurity ≤ 0.15%, the balance is Al.

Preferably, the hardness value of the 6XXX series aluminum alloy is 129HBW, the tensile strength is 411MPa, the yield strength is 348MPa, and the elongation is 15%.

The present invention also provides a method for preparing the 6XXX series aluminum alloy described in the above technical solution, comprising the following steps:

(1) Weigh pure aluminum ingots, pure magnesium ingots, aluminum-silicon master alloys, aluminum-copper master alloys, aluminum-manganese master alloys, aluminum-chromium master alloys, aluminum-yttrium master alloys, and aluminum-zirconium master alloys according to the weight percentage of each element in the aluminum alloy. Master alloys and Al-Sr master alloys;

(2) smelting the raw materials in the step (1) with a refining agent, a covering agent and a refining agent to obtain an aluminum alloy melting solution;

(3) Perform casting, annealing, extrusion, solution treatment and aging treatment on the molten aluminum alloy obtained in the step (2) in sequence to obtain the 6XXX series aluminum alloy.

Preferably, the smelting of the step (2) includes the following steps: (a) after melting the pure aluminum ingot, it is mixed with an aluminum-silicon master alloy, an aluminum-copper master alloy, an aluminum-manganese master alloy, an aluminum-chromium master alloy, and an aluminum-yttrium master alloy , an aluminum-zirconium master alloy, an aluminum-strontium master alloy, a covering agent and a refining agent are mixed, and a smelting is carried out to obtain a primary smelting liquid; (b) the primary smelting liquid obtained in the step (a) is mixed with pure magnesium ingots, and a second smelting is carried out Secondary smelting to obtain a secondary smelting liquid; (c) mixing the secondary smelting liquid obtained in the step (b) with a refiner, performing three smelting, and standing still to obtain an aluminum alloy smelting liquid.

Preferably, the temperature of the primary smelting in the step (a) is 750-800°C.

Preferably, the temperature of the secondary smelting in the step (b) is 720-750°C.

Preferably, the annealing temperature in the step (3) is 520-540° C., and the time is 8-16 hours.

Preferably, the temperature of the solution treatment in the step (3) is 500-540° C., and the time is 1-3 hours.

Preferably, the temperature of the aging treatment in the step (3) is 150-200° C., and the time is 4-12 hours.

The invention provides a 6XXX series aluminum alloy, which is prepared from the following element components in weight percent: Mg 0.8-1.5%, Si 1.5-3.0%, Cu 0.2-0.5%, Mn 0.2-0.5%, Cr 0.1～0.15%, Y0.15～0.4%, Zr 0.1～0.3%, Sr 0.05～0.15%, Ti 0.01～0.04%, Zn≤0.1%, Fe≤0.5%, single impurity≤0.05%, total impurity≤0.15 %, the balance is Al. A small amount of excess Si element in the aluminum alloy of the present invention is dissolved in the aluminum matrix, most of which are distributed in the grain boundary in the form of single-phase silicon or compounds, and excess Si can improve the hardness and strength of the alloy. The joint addition of yttrium and zirconium elements can refine the as-cast structure of aluminum alloy and play a role of fine grain strengthening. It can be seen from the examples that the hardness value of the 6XXX series aluminum alloy of the present invention is 129HBW, the tensile strength reaches 411MPa, the yield strength is 348MPa, and the elongation is 15%.

Description of drawings

Fig. 1 is the scanning electron micrograph of the as-cast ingot of 200 times among the embodiment 1;

Fig. 2 is the scanning electron micrograph of the as-cast ingot of 500 times in embodiment 1;

Fig. 3 is the scanning electron micrograph of extruded ingot in embodiment 1;

Fig. 4 is the scanning electron micrograph of solid solution ingot in embodiment 1;

5 is a transmission electron micrograph of the 6XXX series aluminum alloy in Example 1.

Detailed ways

The invention provides a 6XXX series aluminum alloy, which is prepared from the following element components in weight percent: Mg 0.8-1.5%, Si 1.5-3.0%, Cu 0.2-0.5%, Mn 0.2-0.5%, Cr 0.1～0.15%, Y0.15～0.4%, Zr 0.1～0.3%, Sr 0.05～0.15%, Ti 0.01～0.04%, Zn≤0.1%, Fe≤0.5%, single impurity≤0.05%, total impurity≤0.15 %, the balance is Al.

In the present invention, the raw materials for preparing the 6XXX series aluminum alloy include 0.8-1.5% by weight of Mg, preferably 0.9-1.4%, more preferably 0.92-1.0%.

In the present invention, the raw materials for preparing the 6XXX series aluminum alloy include 1.5-3.0% Si by weight, preferably 1.8-2.5%, more preferably 2.0-2.2%. In the present invention, a small amount of the Si element is solid-dissolved in the aluminum matrix, most of which are distributed in the grain boundary in the form of single-phase silicon or compounds, and excess Si can improve the hardness and strength of the alloy.

In the present invention, the raw materials for preparing the 6XXX series aluminum alloy include 0.2-0.5% Cu by weight, preferably 0.25-0.45%, more preferably 0.3-0.4%.

In the present invention, the raw materials for preparing the 6XXX series aluminum alloy include 0.2-0.5% by weight of Mn, preferably 0.25-0.45%, more preferably 0.3-0.4%.

In the present invention, the raw materials for preparing the 6XXX series aluminum alloy include 0.1-0.15% Cr by weight, preferably 0.11-0.14%, more preferably 0.12-0.13%.

In the present invention, the raw materials for preparing the 6XXX series aluminum alloy include Y with a weight percentage of 0.15-0.4%, preferably 0.20-0.35%, more preferably 0.25-0.30%. In the present invention, the solubility of yttrium in aluminum is small, and a part of it is segregated at the grain boundary to form a compound phase such as _Al3Y , which strengthens the grain boundary, and at the same time can improve the coarseness of Fe, Mn, Cu, Cr, etc. on the grain boundary. The compound phase makes these precipitated phases finer and broken; a part is dissolved in the aluminum matrix, and after aging, it can form finer and dispersed phases such as Al ₃ Y and Al ₃ Zr, which play the role of dispersion strengthening and anchored dislocations. function to enhance the mechanical properties of the alloy.

In the present invention, the raw materials for preparing the 6XXX series aluminum alloy include Zr with a weight percentage of 0.1-0.3%, preferably 0.12-0.25%, more preferably 0.15-0.2%. In the present invention, the joint addition of yttrium and zirconium elements can refine the as-cast structure of the aluminum alloy and play the role of fine grain strengthening.

In the present invention, the raw materials for preparing the 6XXX series aluminum alloy include 0.05-0.15% by weight of Sr, preferably 0.06-0.14%, more preferably 0.08-0.12%. In the present invention, since the aluminum alloy contains more excess Si, a small amount of Sr modifier is added, which can reduce the formation of coarse Si phase, make Si particles more broken, and distribute more uniformly, improving the comprehensiveness of the alloy. performance.

In the present invention, the raw materials for preparing the 6XXX series aluminum alloy include 0.01-0.04% Ti by weight, preferably 0.015-0.03%, more preferably 0.02-0.025%.

In the present invention, the raw materials for preparing the 6XXX series aluminum alloy inevitably include Fe and Zn impurities, wherein the weight percentage content of impurity Zn is preferably ≤0.1%; the weight percentage content of impurity Fe is preferably ≤0.5% . In the present invention, the raw materials for preparing the 6XXX series aluminum alloy inevitably contain impurities other than Fe and Zn, such as boron, sodium, and oxygen. In the present invention, the total of said impurities is ≤0.15%; a single impurity is ≤0.05%.

The present invention also provides a preparation method for the above-mentioned 6XXX series aluminum alloy, comprising the following steps:

(1) Weigh pure aluminum ingots, pure magnesium ingots, aluminum-silicon master alloys, aluminum-copper master alloys, aluminum-manganese master alloys, aluminum-chromium master alloys, aluminum-yttrium master alloys, aluminum-zirconium master alloys, and Master alloy, aluminum strontium master alloy;

(2) smelting the raw materials in the step (1) with a refining agent, a covering agent and a refining agent to obtain an aluminum alloy melting solution;

(3) Perform casting, annealing, extrusion, solution treatment and aging treatment on the molten aluminum alloy obtained in the step (2) in sequence to obtain the 6XXX series aluminum alloy.

The present invention weighs pure aluminum ingots, pure magnesium ingots, aluminum-silicon master alloys, aluminum-copper master alloys, aluminum-manganese master alloys, aluminum-chromium master alloys, aluminum-yttrium master alloys, aluminum Zirconium master alloy and aluminum strontium master alloy. In the present invention, the source of each raw material is not particularly limited, and commercially available products well known to those skilled in the art can be used. The present invention has no special limitation on the weight ratio of the raw materials, as long as the weight percentage of each element satisfies Mg 0.8%-1.5%, Si 1.5-3.0%, Cu 0.2-0.5%, Mn 0.2-0.5%, Cr 0.1～0.15%, Y0.15～0.4%, Zr 0.1～0.3%, Sr 0.05～0.15%, Ti 0.01～0.04%, Zn≤0.1%, Fe≤0.5%, single impurity≤0.05%, total impurity≤0.15 %, and the balance is Al.

After the raw materials are prepared, the present invention melts the raw materials with a refining agent, a covering agent and a refining agent to obtain an aluminum alloy melting liquid. The present invention has no special restrictions on the refining agent, covering agent and refining agent, and the commonly used refining agent, covering agent and refining agent for the preparation of aluminum alloys well known to those skilled in the art can be used. For example, the refining agent is preferably Al- For 5Ti-1B, the covering agent is preferably 45% NaCl+45% KCl+10% Na ₃ AlF ₆ , and the refining agent is preferably C ₂ F ₆ . In the present invention, the mass ratio of the raw material, refining agent, covering agent and refining agent is preferably 150-200:2:2:1, more preferably 160-190:2:2:1, most preferably 170 ~180:2:2:1.

In the present invention, the smelting preferably includes the following steps: (a) after melting the pure aluminum ingot, it is mixed with aluminum-silicon master alloy, aluminum-copper master alloy, aluminum-manganese master alloy, aluminum-chromium master alloy, aluminum-yttrium master alloy, aluminum zirconium master alloy, aluminum strontium master alloy, covering agent and refining agent are mixed, and a primary melting is carried out to obtain a primary melting; (b) the primary melting obtained in the step (a) is mixed with pure magnesium ingots, and a secondary melting is carried out , to obtain a secondary smelting solution; (c) mixing the secondary smelting solution obtained in the step (b) with a refiner, performing three smelting, and standing still to obtain an aluminum alloy smelting solution. In the present invention, the melting temperature of the pure aluminum ingot is preferably 730-780°C, more preferably 740-770°C, most preferably 750-760°C. In the present invention, the temperature of the primary smelting is preferably 750-800°C, more preferably 760-790°C, and most preferably 770-780°C. In the present invention, the temperature of the secondary smelting is preferably 720-750°C, more preferably 725-745°C, most preferably 730-740°C. In the present invention, the temperature of the tertiary melting is preferably 730-740°C. In the present invention, the standing time is preferably 20-40 minutes. The present invention has no special limitation on the melting time of the pure aluminum ingot, the first melting time, the second melting time and the third melting time, as long as the alloy can be completely melted.

After the primary smelting is completed, the present invention preferably performs the first degassing and slag removal treatment.

After the secondary smelting is finished, the present invention preferably adds a slagging agent to carry out the second slagging treatment.

After the aluminum alloy melting liquid is obtained, the present invention sequentially performs casting, annealing, extrusion, solution treatment and aging treatment on the aluminum alloy melting liquid to obtain the 6XXX series aluminum alloy.

In the present invention, the temperature of the molten aluminum alloy during casting is preferably 730-740°C. In the present invention, the hydraulic pressure of the casting is preferably 0.01-0.03 MPa, more preferably 0.015-0.025 MPa, most preferably 0.02 MPa. In the present invention, the casting speed is preferably 20-30 mm/min, more preferably 22-28 mm/min, most preferably 24-26 mm/min. The present invention has no special limitation on the shape of the ingot after casting, and those skilled in the art can choose according to actual needs. In the embodiment of the present invention, the diameter of the ingot is preferably 126 mm, and the length is preferably 400-410 mm.

In the present invention, the annealing temperature is preferably 520-540°C, more preferably 525-535°C, and most preferably 528-532°C. In the present invention, the annealing time is preferably 8-16 hours, more preferably 10-15 hours, and most preferably 12-14 hours. In the present invention, after the annealing is finished, the present invention preferably air-cools the annealed ingot to 25°C.

In the present invention, the extrusion preferably includes sequentially heating the annealed ingot, keeping it warm and then extruding. In the present invention, the heating temperature is preferably 440-460°C, more preferably 445-455°C, most preferably 450°C; the heat preservation time is preferably 10-12h. In the present invention, the temperature of the extrusion cylinder during the extrusion is preferably 460-480°C, more preferably 465-475°C, most preferably 470°C; the extrusion speed is preferably 8-12m/min, It is more preferably 9-11 m/min, most preferably 10 m/min; the extrusion ratio of the extrusion is preferably 20-30. In the present invention, before the annealed ingot is extruded, in order to avoid scratches on the surface of the ingot, it is preferable to carve the annealed ingot to a diameter of 122 mm and a length of 300 mm.

In the present invention, the solution treatment temperature is preferably 500-540°C, more preferably 510-535°C, and most preferably 520-530°C. In the present invention, the solution treatment time is preferably 1-3 hours, more preferably 1.5-2.5 hours, and most preferably 2.0-2.3 hours. In the present invention, after the solid solution is completed, the present invention preferably water-cools the ingot to room temperature.

In the present invention, the aging treatment temperature is preferably 150-200°C, more preferably 160-190°C, most preferably 170-180°C. In the present invention, the aging treatment time is preferably 4-12 hours, more preferably 6-10 hours, and most preferably 8 hours. In the present invention, after the aging treatment, the present invention preferably air-cools the aging-treated product to room temperature.

A small amount of excess Si element in the aluminum alloy raw material of the present invention is dissolved in the aluminum matrix, most of which are distributed at the grain boundaries in the form of single-phase silicon or compounds, and the excess Si can improve the hardness and strength of the aluminum alloy; It contains more excess Si, so a small amount of Sr modifier is added, which can reduce the formation of coarse Si phase, make Si particles more broken, distribute more uniformly, and improve the overall performance of the alloy. The joint addition of yttrium and zirconium can refine the as-cast structure of aluminum alloy and play a role of fine grain strengthening. The solubility of yttrium in aluminum is small, and a part of it is segregated at the grain boundary to form _Al3Y and other compound phases to strengthen the grain boundary, and at the same time, it can improve the coarse Fe, Mn, Cu, Cr and other compound phases on the grain boundary, so that these The precipitated phases are finer and broken; a part of yttrium and zirconium are dissolved in the aluminum matrix, and after aging, they can form finer and dispersed phases such as Al ₃ Y and Al ₃ Zr, which play the role of dispersion strengthening and pinned dislocations. Enhance the mechanical properties of the alloy.

The 6XXX series aluminum alloy provided by the present invention has excellent comprehensive performance, the hardness value is 129HBW, the tensile strength is 411MPa, the yield strength is 348MPa, and the elongation is 15%. It also has good machining performance and cutting performance, and can be used in ABS, OA, optical instrument parts, etc.

The 6XXX series aluminum alloy provided by the present invention and its preparation method will be described in detail below in conjunction with examples, but they should not be construed as limiting the protection scope of the present invention.

Example 1

A 6XXX series aluminum alloy prepared from the following elemental components in weight percent: Mg 0.92%, Si 2.0%, Cu 0.3%, Mn 0.4%, Cr 0.1%, Y 0.25%, Zr 0.15%, Sr 0.10%, Ti 0.02%, Zn 0.1%, Fe 0.2%, single impurity ≤ 0.05%, total impurity ≤ 0.15%, the balance is Al.

The preparation method comprises the following steps:

(1) Weigh pure aluminum ingots, pure magnesium ingots, aluminum-silicon master alloys, aluminum-copper master alloys, aluminum-manganese master alloys, aluminum-chromium master alloys, aluminum-yttrium master alloys, and aluminum-zirconium master alloys according to the weight percentages of the above elements , Al-Sr master alloy;

(2) After melting the pure aluminum ingot at 780°C, add aluminum-silicon master alloy, aluminum-copper master alloy, aluminum-manganese master alloy, aluminum-chromium master alloy, aluminum-yttrium master alloy, aluminum-zirconium master alloy, aluminum-strontium master alloy, covering agent and refining agent, conduct a smelting at 780°C to obtain a primary smelting liquid; lower the temperature to 730°C, mix the obtained primary smelting liquid with pure magnesium ingots, and perform secondary smelting to obtain a secondary smelting liquid; The smelting liquid is mixed with aluminum titanium boron, smelted three times at 730°C, and left standing for 20 minutes to obtain the aluminum alloy smelting liquid;

(3) Cast the molten aluminum alloy obtained in the step (2) at 740°C, with a water pressure of 0.03MPa and a speed of 30mm/min to obtain an as-cast ingot with a diameter of 126mm and a length of 410mm ;The as-cast ingot was annealed at 540°C for 8 hours, and cooled in the air to obtain the annealed ingot; the annealed ingot was cut to a diameter of 122mm, and the length was sawed to 300mm to obtain a wagon ingot; the wagon ingot was heated to 440°C Insulate for 12 hours, then come out of the furnace; extrude under the conditions of extrusion cylinder temperature of 480°C, extrusion speed of 12m/min, and extrusion ratio of 25 to obtain an extruded ingot; the extruded ingot is solution treated at 510°C for 2h, A solid solution ingot is obtained; the solid solution ingot is aged at 170° C. for 8 hours to obtain the 6XXX series aluminum alloy.

Using GB/T231.1-2002 to measure the hardness of 6XXX series aluminum alloy, the result is that the hardness is 113HBW.

Using GB/T228-2002 to measure the tensile strength, yield strength and elongation of 6XXX series aluminum alloy, the result is that the tensile strength is 371MPa, the yield strength is 313MPa, and the elongation is 14.4%.

The microstructure of the as-cast ingot was observed by 200X and 500X scanning electron microscopes, and the results are shown in Figure 1 and Figure 2, respectively. It can be seen from Fig. 1 and Fig. 2 that the as-cast ingot has relatively uniform and fine equiaxed grains with small anisotropy, uniform deformation and good plasticity during processing, which is conducive to subsequent processing; in addition, from the figure Obvious segregation can be seen; at the same time, there are still some undissolved residual phases. The EDS energy spectrum analysis of several positions in the figure shows that the white and relatively coarse second phase is mainly the non-equilibrium phase of Si and Cu elements, and the gray and finer second phase mainly contains insoluble phases such as Fe, Mn and Cr. , and a small amount of Mg ₂ Si. Therefore, as-cast ingots need to be annealed to eliminate segregation.

SEM was used to observe the microstructure of extruded ingots and solid solution ingots, and the results are shown in Figure 3 and Figure 4, respectively. Combining Figure 3 and Figure 4, it can be seen that the extruded ingot is fibrous along the extrusion direction, and there are a large number of residual phases on the grain boundaries. After solid solution treatment, the residual phase in the grain basically dissolves into the matrix, most of the residual phase on the grain boundary dissolves, and the alloy structure becomes more uniform. The solid-solution ingot of the present invention forms relatively sufficient supersaturated solid solution, which is conducive to the precipitation of more and more dispersed strengthening phases during aging treatment, and enhances the mechanical properties of the aluminum alloy.

The microstructure of the 6XXX series aluminum alloy was observed by transmission electron microscopy, and the results are shown in Figure 5. It can be seen from Fig. 5 that: Al ₃ Y, Al ₃ Zr and other precipitates are evenly distributed, the size is between 50 and 150 nm, they are spherical and massive, and their shapes are similar. There are larger-sized precipitated phases at the grain boundaries, which can strengthen the grain boundaries to a certain extent; at the same time, the aluminum alloy disperses and uniformly precipitates the needle-like Mg ₂ Si phase, and this β" phase has the best strengthening effect, which can make the aluminum alloy The alloy has the best mechanical properties, and Al ₃ Y, Al ₃ Zr and other precipitated phases are relatively evenly distributed.

Example 2

A 6XXX series aluminum alloy prepared from the following elemental components in weight percent: Mg 0.90%, Si 2.2%, Cu 0.3%, Mn 0.4%, Cr 0.12%, Y 0.27%, Zr 0.15%, Sr 0.10%, Ti 0.03%, Zn 0.09%, Fe 0.17%, single impurity ≤ 0.05%, total impurity ≤ 0.15%, the balance is Al.

The preparation method comprises the following steps:

(1) Weigh pure aluminum ingots, pure magnesium ingots, aluminum-silicon master alloys, aluminum-copper master alloys, aluminum-manganese master alloys, aluminum-chromium master alloys, aluminum-yttrium master alloys, and aluminum-zirconium master alloys according to the weight percentages of the above elements , Al-Sr master alloy;

(2) After melting the pure aluminum ingot at 780°C, add aluminum-silicon master alloy, aluminum-copper master alloy, aluminum-manganese master alloy, aluminum-chromium master alloy, aluminum-yttrium master alloy, aluminum-zirconium master alloy, aluminum-strontium master alloy, covering agent and refining agent, conduct a smelting to obtain a primary smelting solution; lower the temperature to 730°C, mix the obtained primary smelting solution with pure magnesium ingots, and perform secondary smelting to obtain a secondary smelting solution; mix the obtained secondary smelting solution with Aluminum, titanium and boron are mixed, smelted three times at 730°C, and left to stand for 15 minutes to obtain aluminum alloy smelting liquid;

(3) Cast the molten aluminum alloy obtained in the step (2) at 730°C, with a water pressure of 0.025MPa and a speed of 25mm/min to obtain a cast state with a diameter of 126mm and a length of 400-410mm Ingot casting; the as-cast ingot is annealed at 530°C for 12 hours, cooled in the air out of the furnace to obtain annealed ingot; the annealed ingot car body is cut to a diameter of 122mm, and the length is sawed to 300mm to obtain a car body ingot; the car body ingot is heated Heat at 450°C for 10 hours, then come out of the furnace; extrude under the conditions of extrusion cylinder temperature of 470°C, extrusion speed of 10m/min, and extrusion ratio of 25; the extruded ingot is solution treated at 530°C for 2h, and then Aging treatment at 180° C. for 8 hours to obtain the 6XXX series aluminum alloy.

The hardness of the 6XXX series aluminum alloy was measured by the same method as in Example 1, and the result was that the hardness was 126HBW.

The tensile strength, yield strength and elongation of the 6XXX series aluminum alloy were measured by the same method as in Example 1. The results showed that the tensile strength was 411 MPa, the yield strength was 348 MPa, and the elongation was 15%.

Example 3

A 6XXX series aluminum alloy prepared from the following elemental components in weight percent: 1.1% Mg, 2.0% Si, 0.32% Cu, 0.39% Mn, 0.11% Cr, 0.28% Y, 0.16% Zr, Sr 0.09%, Ti 0.025%, Zn 0.1%, Fe 0.16%, single impurity ≤ 0.05%, total impurity ≤ 0.15%, the balance is Al.

The preparation method comprises the following steps:

(1) Weigh pure aluminum ingots, pure magnesium ingots, aluminum-silicon master alloys, aluminum-copper master alloys, aluminum-manganese master alloys, aluminum-chromium master alloys, aluminum-yttrium master alloys, and aluminum-zirconium master alloys according to the weight percentages of the above elements , Al-Sr master alloy;

(2) After melting the pure aluminum ingot at 730°C, add aluminum-silicon master alloy, aluminum-copper master alloy, aluminum-manganese master alloy, aluminum-chromium master alloy, aluminum-yttrium master alloy, aluminum-zirconium master alloy, aluminum-strontium master alloy, covering agent and refining agent, conduct a smelting to obtain a primary smelting solution; lower the temperature to 730°C, mix the obtained primary smelting solution with pure magnesium ingots, and perform secondary smelting to obtain a secondary smelting solution; mix the obtained secondary smelting solution with Aluminum, titanium and boron are mixed, smelted three times at 730°C, and left to stand for 25 minutes to obtain aluminum alloy smelting liquid;

(3) Cast the molten aluminum alloy obtained in the step (2) at 740°C, with a hydraulic pressure of 0.03 MPa and a speed of 30 mm/min to obtain a cast state with a diameter of 126 mm and a length of 400 to 410 mm Ingot casting; the as-cast ingot is annealed at 535°C for 14 hours, and cooled in the air when it comes out of the furnace; the annealed ingot is cut to a diameter of 122mm, and the length is sawed to 300mm, and the ingot is cast into an ingot; the ingot is heated to 450°C and kept for 12 hours , out of the furnace; extruded under the conditions of extrusion cylinder temperature of 475°C, extrusion speed of 10m/min, and extrusion ratio of 25 to obtain an extruded ingot; the extruded ingot was solution treated at 540°C for 2 hours to obtain a solution cast Ingot; solid solution ingot aging treatment at 170° C. for 10 h to obtain the 6XXX series aluminum alloy.

The hardness of the 6XXX series aluminum alloy was measured by the same method as in Example 1, and the result was that the hardness was 117HBW.

The tensile strength, yield strength and elongation of the 6XXX series aluminum alloy were measured by the same method as in Example 1. The results showed that the tensile strength was 396MPa, the yield strength was 331MPa, and the elongation was 14.6%.

The above is only a preferred embodiment of the present invention, it should be pointed out that, for those of ordinary skill in the art, without departing from the principle of the present invention, some improvements and modifications can also be made, and these improvements and modifications can also be made. It should be regarded as the protection scope of the present invention.

Claims (7)

1. A 6XXX series aluminum alloy prepared from the following elemental components in weight percentage: Mg 0.8%~1.5%, Si 1.5~3.0%, Cu 0.2~0.5%, Mn 0.2~0.5%, Cr 0.1 ~0.15%, Y 0.15~0.4%, Zr 0.1~0.3%, Sr0.05~0.15%, Ti 0.01~0.04%, Zn≤0.1%, Fe≤0.5%, single impurity≤0.05%, total impurity≤0.15% , the balance is Al; The preparation method of above-mentioned 6XXX series aluminum alloy comprises the following steps: (1) Weigh pure aluminum ingots, pure magnesium ingots, aluminum-silicon master alloys, aluminum-copper master alloys, aluminum-manganese master alloys, aluminum-chromium master alloys, aluminum-yttrium master alloys, aluminum-zirconium master alloys, Aluminum strontium master alloy; (2) Melting the raw materials in the step (1) with a refining agent, a covering agent and a refining agent to obtain an aluminum alloy melting liquid; (3) sequentially performing casting, annealing, extrusion, solution treatment and aging treatment on the molten aluminum alloy obtained in the step (2) to obtain the 6XXX series aluminum alloy; The annealing temperature in the step (3) is 520~540°C, and the time is 8~16h; The temperature of the solution treatment in the step (3) is 500-540° C., and the time is 1-3 hours; The temperature of the aging treatment in the step (3) is 150-200° C., and the time is 4-12 hours. 2. The 6XXX series aluminum alloy according to claim 1, characterized in that it is prepared from the following elemental components in weight percent: Mg 0.92%, Si 2.0%, Cu 0.3%, Mn 0.4%, Cr 0.1 %, Y 0.25%, Zr 0.15%, Sr0.10%, Ti 0.02%, Zn≤0.1%, Fe≤0.2%, single impurity≤0.05%, total impurity≤0.15%, and the balance is Al. 3. The 6XXX series aluminum alloy according to claim 1 or 2, wherein the hardness of the 6XXX series aluminum alloy is 129HBW, the tensile strength is 411MPa, the yield strength is 348MPa, and the elongation is 15%. 4. The preparation method of the 6XXX series aluminum alloy described in any one of claims 1 to 3, comprising the following steps: (1) Weigh pure aluminum ingots, pure magnesium ingots, aluminum-silicon master alloys, aluminum-copper master alloys, aluminum-manganese master alloys, aluminum-chromium master alloys, aluminum-yttrium master alloys, aluminum-zirconium master alloys, Aluminum strontium master alloy; (2) Melting the raw materials in the step (1) with a refining agent, a covering agent and a refining agent to obtain an aluminum alloy melting liquid; (3) sequentially performing casting, annealing, extrusion, solution treatment and aging treatment on the molten aluminum alloy obtained in the step (2) to obtain the 6XXX series aluminum alloy; The annealing temperature in the step (3) is 520~540°C, and the time is 8~16h; The temperature of the solution treatment in the step (3) is 500-540° C., and the time is 1-3 hours; The temperature of the aging treatment in the step (3) is 150-200° C., and the time is 4-12 hours. 5. The preparation method according to claim 4, characterized in that the smelting in step (2) includes the following steps: (a) after melting the pure aluminum ingot, it is mixed with aluminum-silicon master alloy, aluminum-copper master alloy, aluminum Manganese master alloy, aluminum-chromium master alloy, aluminum-yttrium master alloy, aluminum-zirconium master alloy, aluminum-strontium master alloy, covering agent and refining agent are mixed, and a smelting is carried out to obtain a primary smelting liquid; (b) the step (a) The obtained primary smelting liquid is mixed with pure magnesium ingots, and the secondary smelting is carried out to obtain the secondary smelting liquid; (c) the secondary smelting liquid obtained in the step (b) is mixed with the refiner, and the third smelting is carried out, and the , to obtain aluminum alloy smelting solution. 6 . The preparation method according to claim 5 , wherein the temperature of the primary smelting in the step (a) is 750-800° C. 7. The preparation method according to claim 5 or 6, characterized in that the temperature of the secondary smelting in the step (b) is 720-750°C.