CN113215451B - High-strength Al-Mg-Si-Cu aluminum alloy and preparation method thereof - Google Patents

Abstract

The invention discloses a high-strength Al-Mg-Si-Cu alloy and a preparation method thereof, and the high-strength Al-Mg-Si-Cu alloy comprises the following components in percentage by mass: 0.75-1.10 wt.%, Fe: 0.35 wt.%, Cu: 0.75-1.0 wt.%, Mn: 0.5-0.75 wt.%, Mg: 0.85-1.30 wt.%, Cr: less than or equal to 0.05 wt.%, Ti: not more than 0.10 wt.%, the balance being Al, the sum of the mass percentages of the components being 100%, and the mass ratio of (Mg + Si)/Cu being controlled to be 1.6-3.2, mixing the raw materials, and carrying out smelting, casting, homogenizing treatment, hot extrusion, quenching and aging treatment to obtain the high-strength Al-Mg-Si-Cu alloy. According to the Al-Mg-Si-Cu alloy, 0.85-1.30 wt.% of Mg element is added, and the mass ratio of (Mg + Si)/Cu is strictly controlled, so that the alloy material with the strength of more than 450MPa can be prepared.

Description

A kind of high-strength Al-Mg-Si-Cu series aluminum alloy and preparation method thereof

technical field

The invention belongs to the technical field of aluminum alloys, and in particular relates to a high-strength Al-Mg-Si-Cu series aluminum alloy and a preparation method thereof.

Background technique

With the vigorous development of new energy vehicles, the trend of lightweight vehicles has attracted more and more attention. Al-Mg-Si-(Cu) alloys are widely used in new energy vehicles due to their excellent corrosion resistance, weldability and formability. However, its strength is generally in the 300MPa class. In order to achieve high efficiency, energy saving and environmental protection, it is of great significance to develop Al-Mg-Si-(Cu) alloys with higher strength.

At present, the Al-Mg-Si-(Cu) alloys widely used in new energy vehicles mainly include alloys with low Cu content 6063, 6005A, 6082 and 6061 with medium Cu content. However, the strength of these alloys is generally below 400MPa; in addition, in order to further improve the strength of Al-Mg-Si-(Cu) alloys, on the basis of the above alloys, the Cu content is further increased, and 6111 and 6013 with high Cu content have been developed. and other alloys. The Cu content of these alloys is up to 1% by weight, and although their strength can reach 400MPa, none of the above alloys can meet the requirements for alloys with a strength of 450MPa; The development of 450MPa grade Al-Mg-Si-(Cu) alloy is still a technical difficulty at present.

SUMMARY OF THE INVENTION

In view of the deficiencies of the prior art, the purpose of the present invention is to provide a high-strength Al-Mg-Si-(Cu) alloy and a preparation method thereof, the strength of which can reach 450MPa.

In order to achieve the above object, the present invention provides the following technical solutions:

A high-strength Al-Mg-Si-Cu alloy, the composition of which, by mass percentage, comprises: Si: 0.75-1.10wt.%, Fe:≤0.35wt.%, Cu: 0.75-1.0wt.%, Mn: 0.5～0.75wt.%, Mg: 0.85～1.30wt.%, Cr: ≤0.05wt.%, Ti: ≤0.10wt.%, the balance is Al, the sum of the mass percentage of each component is 100%, control (Mg The mass ratio of +Si)/Cu is 1.6 to 3.2.

In the present invention, by adding 0.85-1.30 wt.% Mg element, the content of Mg element required for supplementing the Q phase (Al ₅ Cu ₂ Mg ₈ Si ₆ ) as much as possible is strictly controlled, and (Mg+Si)/Cu is strictly controlled. On the one hand, the content of the strengthening phase Q phase (Al ₅ Cu ₂ Mg ₈ Si ₆ ) can be increased as much as possible, and on the other hand, the formation of excessive θ phase (Al ₂ Cu) can be avoided, thereby significantly improving the strength of the alloy material. An Al-Mg-Si-Cu alloy of 450MPa grade was obtained.

Preferably, the mass ratio of (Mg+Si)/Cu is 2.2. In the present invention, the mass ratio of (Mg+Si)/Cu is preferably 2.2, which can form the Q phase (Al ₅ Cu ₂ Mg ₈ Si ₆ ) with the largest volume fraction, while avoiding the formation of excessive theta phase (Al ₂ Cu), so as to maximize the to enhance the strength of the alloy material.

The present invention also provides a method for preparing the above-mentioned high-strength Al-Mg-Si-Cu series alloy. The raw materials are mixed and batched, and the high-strength alloy is obtained through smelting, ingot casting, homogenization treatment, hot extrusion, quenching and aging treatment. Al-Mg-Si-Cu alloy.

Preferably, the temperature of the smelting is 720-760°C.

Preferably, the ingot is in a semi-continuous ingot casting method, the casting temperature is 690-710° C., and the casting speed is 45-140 mm/min.

Preferably, the homogenizing treatment process is as follows: heating the ingot to 530-560°C and keeping the temperature for 1-10 hours, then cooling to 400-450°C at a rate of not more than 15°C/min, and then cooling to 400-450°C at a rate of not less than 30°C/min. The rate of min cooling to below 180 ℃ cooling.

Preferably, the process parameters of the hot extrusion are as follows: the homogenized ingot is heated to 500-530°C, the temperature of the extrusion cylinder is 430-500°C, and the extrusion speed of the extruded material is 4-20 m/min.

Preferably, the quenching temperature is not lower than 535°C, and the quenching cooling medium is water.

Preferably, the temperature of the aging treatment is 100-200° C., and the time is 1-48 h.

In the present invention, by adding 0.85-1.30wt.% Mg element and strictly controlling the mass ratio of (Mg+Si)/Cu, on the one hand, the content of the strengthening phase Q phase (Al ₅ Cu ₂ Mg ₈ Si ₆ ) is increased as much as possible, On the other hand, the formation of excessive theta phase (Al ₂ Cu) is avoided. During the preparation process of the alloy material, the Q phase plays the role of precipitation strengthening, thereby significantly improving the strength of the alloy material, and obtaining 450MPa grade Al-Mg-Si- Cu-based alloys.

Compared with the prior art, the advantages of the present invention are:

The Al-Mg-Si-Cu alloy of the present invention can be prepared by adding 0.85-1.30 wt.% Mg element and strictly controlling the mass ratio of (Mg+Si)/Cu to obtain an alloy material with a strength of more than 450 MPa.

Detailed ways

All materials, reagents and instruments selected in the present invention are well known in the art, but do not limit the implementation of the present invention, and some other reagents and equipment well known in the art are applicable to the implementation of the following embodiments of the present invention.

Example 1

A high-strength Al-Mg-Si-Cu alloy, its chemical composition is: Si: 0.75%, Fe: 0.18%, Cu, 1.00%, Mn: 0.60%, Mg: 0.85%, Cr: 0.05% by mass percentage , Ti: 0.068%, the remainder is Al, the sum of the mass percentages of each component is 100%; the mass ratio of (Mg+Si)/Cu is 1.6. The alloy of this composition was used to prepare a 6 mm thick extrusion with an extrusion ratio of 20.

The described alloy extrusion material preparation method comprises the following steps:

S1 smelting: ingredients according to the set proportion, smelting and melting raw materials at 740 ℃, fully stirring, degassing and slag removal;

S2 ingot: obtain the melt that meets the requirements by smelting, and cast the ingot for extrusion at 700°C by the semi-continuous casting method;

S3 Homogenization treatment: The ingot is heated to 560°C and kept for 1 h, then cooled to 450°C at a rate of 10°C/min, and then cooled to below 180°C at a rate of 45°C/min. the ingot after

S4 hot extrusion: heating the homogenized ingot obtained in step (3) to 530°C, the extrusion cylinder temperature is 500°C, and then extruding at an extrusion speed of 20 m/min;

S5 quenching: the quenching temperature is 535℃, the extruded material flows out of the die hole and enters the online quenching device for water quenching treatment;

S6 Aging: The quenched extruded material is heated to 100°C and kept for 48 hours for aging treatment. After being released from the furnace, the high-strength Al-Mg-Si-Cu alloy extruded material is obtained. The mechanical properties of the obtained extruded material are shown in Table 1. .

Example 2

A high-strength Al-Mg-Si-Cu alloy, its chemical composition is: Si: 1.10%, Fe: 0.18%, Cu, 0.75%, Mn: 0.50%, Mg: 1.30%, Cr: 0.05% by mass percentage , Ti: 0.06%, the balance is Al, the sum of the mass percentages of each component is 100%; the mass ratio of (Mg+Si)/Cu is 3.2. The alloy of this composition was used to prepare a 6 mm thick extrusion with an extrusion ratio of 20.

The described alloy extrusion material preparation method comprises the following steps:

S1 smelting: ingredients according to the set proportion, smelting and melting raw materials at 740 ℃, fully stirring, degassing and slag removal;

S2 ingot: obtain the melt that meets the requirements by smelting, and cast the ingot for extrusion at 700°C by the semi-continuous casting method;

S3 Homogenization treatment: the ingot is heated to 530°C and kept for 10h, then cooled to 400°C at a rate of 5°C/min, and then cooled to below 180°C at a rate of not less than 50°C/min. Ingot after quality treatment;

S4 hot extrusion: heating the ingot after the homogenization treatment obtained in step (3) to 500 ° C, the extrusion barrel temperature is 430 ° C, and then extruding at an extrusion speed of 4 m/min;

S5 quenching: the quenching temperature is 535℃, the extruded material flows out of the die hole and enters the online quenching device for water quenching treatment;

S6 aging: the quenched extruded material is heated to 200°C, and kept for 1 h for aging treatment. After being released from the furnace, the high-strength Al-Mg-Si-Cu alloy extruded material is obtained. The mechanical properties of the obtained extruded material are shown in Table 1. .

Example 3

A high-strength Al-Mg-Si-Cu alloy, its chemical composition is: Si: 0.9%, Fe: 0.18%, Cu, 0.95%, Mn: 0.60%, Mg: 1.2%, Cr: 0.05% by mass percentage , Ti: 0.068%, the remainder is Al, the sum of the mass percentages of each component is 100%; the mass ratio of (Mg+Si)/Cu is 2.2. The alloy of this composition was used to prepare a 6 mm thick extrusion with an extrusion ratio of 20.

The described alloy extrusion material preparation method comprises the following steps:

S1 smelting: ingredients according to the set proportion, smelting and melting raw materials at 740 ℃, fully stirring, degassing and slag removal;

S2 ingot: obtain the melt that meets the requirements by smelting, and cast the ingot for extrusion at 700 ℃ by the semi-continuous ingot casting method;

S3 Homogenization treatment: The ingot is heated to 540°C and kept for 8 hours, then cooled to 400°C at a rate of 10°C/min, and then cooled to below 180°C at a rate of 30°C/min. the ingot after

S4 hot extrusion: heating the ingot after the homogenization treatment obtained in step (3) to 500°C, the temperature of the extrusion cylinder is 430°C, and then extruding at an extrusion speed of 12 m/min;

S5 quenching: the quenching temperature is 535℃, the extruded material flows out of the die hole and enters the online quenching device for water quenching treatment;

S6 Aging: The quenched extruded material is heated to 160°C and kept for 24 hours for aging treatment. After being released from the furnace, the high-strength Al-Mg-Si-Cu alloy extruded material is obtained. The mechanical properties of the obtained extruded material are shown in Table 1. .

Comparative Example 1

The chemical composition of the alloy used in Comparative Example 1 is: Si: 0.85%, Fe: 0.18%, Cu, 1.2%, Mn: 0.60%, Mg: 0.90%, Cr: 0.05%, Ti: 0.05%, the remainder is Al, and the sum of the mass percentages of each component is 100%; the mass ratio of (Mg+Si)/Cu is 1.46. The preparation method is the same as that of Example 1. The mechanical properties of the obtained extruded materials are shown in Table 1.

Comparative Example 2

The chemical composition of the alloy used in Comparative Example 2 is: Si: 1.10%, Fe: 0.18%, Cu, 0.70%, Mn: 0.50%, Mg: 1.30%, Cr: 0.05%, Ti: 0.06%, the remainder is Al, and the sum of the weight percentages of each component is 100%; the mass ratio of (Mg+Si)/Cu is 3.43. The casting, homogenization and aging processes are the same as in Example 1, and the extrusion process is as follows: the ingot is heated to 500°C, the extrusion barrel temperature is 450°C, the extrusion speed of the extruded material is 8m/min; the quenching temperature is 520°C , the quenching method is online water quenching. The mechanical properties of the obtained extruded materials are shown in Table 1.

Mechanical property test: According to GBT228.1-2010 Tensile Test of Metal Materials Part 1 Room temperature test method, the test and analysis are carried out.

Table 1 Mechanical properties index of the extruded materials described in Examples 1-3 and Comparative Examples 1-2

sample Tensile strength/MPa Yield strength/MPa Elongation/% Example 1 452 421 11.5% Example 2 468 432 10.1% Example 3 472 445 10.3% Comparative Example 1 406 374 10.8% Comparative Example 2 419 382 12.0%

Claims (7)

1. A preparation method of high-strength Al-Mg-Si-Cu alloy is characterized by comprising the following steps: the high-strength Al-Mg-Si-Cu alloy comprises the following components in percentage by mass: 0.75-1.10 wt.%, Fe: 0.35 wt.%, Cu: 0.75-1.0 wt.%, Mn: 0.5-0.75 wt.%, Mg: 0.85-1.30 wt.%, Cr: less than or equal to 0.05 wt.%, Ti: not more than 0.10 wt.%, the balance being Al, the sum of the mass percentages of the components being 100%, and the mass ratio of (Mg + Si)/Cu being 2.2;

the preparation method of the high-strength Al-Mg-Si-Cu alloy comprises the following steps: mixing the raw materials, smelting, casting, homogenizing, hot extruding, quenching and aging to obtain the high-strength Al-Mg-Si-Cu alloy.

2. The method of claim 1, wherein: the smelting temperature is 720-760 ℃.

3. The method of claim 1, wherein: the casting adopts a semi-continuous casting mode, the casting temperature is 690-710 ℃, and the casting speed is 45-140 mm/min.

4. The method of claim 1, wherein: the homogenizing treatment process comprises the following steps: heating the cast ingot to 530-560 ℃, preserving heat for 1-10 h, then cooling to 400-450 ℃ at a speed of not more than 15 ℃/min, and then cooling to below 180 ℃ at a speed of not less than 30 ℃/min.

5. The method of claim 1, wherein: the technological parameters of the hot extrusion are as follows: heating the ingot after homogenizing treatment to 500-530 ℃, wherein the temperature of an extrusion cylinder is 430-500 ℃, and the extrusion speed of an extrusion material is 4-20 m/min.

6. The method of claim 1, wherein: the quenching temperature is not lower than 535 ℃, and the quenching cooling medium is water.

7. The method of claim 1, wherein: the temperature of the aging treatment is 100-200 ℃, and the time is 1-48 h.