A 6-series aluminum alloy with high strength and low standing effect and its preparation method

Abstract

The present invention relates to a 6-series aluminum alloy with high strength and low aging effect and a preparation method thereof. By mass percentage, it consists of the following components: Mg: 0.70 - 1.20%; Si: 0.80 - 1.30%; Cu: ≤0.50%; Mn: ≤0.60%; Cr: ≤0.30%; Zr: ≤0.20%; Sn: 0.05 - 0.20%; Fe: ≤0.35%; other inevitable impurity elements, and the balance is Al. Through strictly limiting the Mg / Si ratio and trace amounts of Sn, the product obtained by the present invention has excellent strength and low aging effect, and has good application prospects.

Description

Technical Field

[0001] The present invention belongs to the field of aluminum alloys, and in particular relates to a 6-series aluminum alloy with high strength and low parking effect and a preparation method thereof. Background Art

[0002] 6-series aluminum profiles are increasingly used in vehicle bodies. Besides their obvious lightweight advantages, their excellent recyclability, extrudability, and heat treatability make them an essential component of vehicle body materials, particularly for structural components. Currently, with the increasing demand for lightweight vehicles, material strength requirements are also increasing. High-strength 6-series aluminum profiles exhibit a significant stagnation effect. This means that if the extruded profile is left standing for a period of time before undergoing artificial aging, the mechanical properties of the profile will significantly degrade. In practice, artificial aging often fails to occur promptly after extrusion, resulting in a large number of defective products. Limited research has been conducted on how to mitigate the stagnation effect of high-strength aluminum profiles. Therefore, the development of aluminum profiles with high strength and low stagnation effect is of great significance for production practice. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to provide a 6 series aluminum alloy with high strength and low parking effect and a preparation method thereof. By strictly limiting the Mg / Si ratio and a trace amount of Sn, the obtained product has excellent strength and low parking effect, and has good application prospects.

[0004] The present invention provides a 6 series aluminum alloy with high strength and low parking effect, which is composed of the following components by mass percentage: Mg: 0.70-1.20%;

[0005] Si: 0.80-1.30%;

[0006] Cu: ≤0.50%;

[0007] Mn: ≤0.60%;

[0008] Cr: ≤0.30%;

[0009] Zr: ≤0.20%;

[0010] Sn: 0.05-0.20%;

[0011] Fe: ≤0.35%; other unavoidable impurity elements, the rest is Al;

[0012] Among them, the Mg / Si ratio is 0.70-1.00.

[0013] The individual content of the unavoidable impurity elements is ≤0.05%, and the total content is ≤0.15%.

[0014] The present invention provides a method for preparing a 6-series aluminum alloy with high strength and low standing effect, comprising the following steps:

[0015] Add the prepared aluminum alloy raw materials into a melting furnace. After online refining, online degassing, and online filtering of the melt, cast the liquid aluminum alloy into an aluminum alloy ingot. Subsequently, homogenize at 550 - 590 °C for 5 - 10 h, and cool with strong wind or water mist. Preheat the homogenized ingot to 500 °C ± 30 °C, perform extrusion production, with the quenching temperature ≥ 500 °C, and cool by water mist or water cooling. Produce profiles according to the parameters of 150 - 180 °C / 4 - 12 h or 190 - 210 °C / 2 - 8 h to obtain a 6-series aluminum alloy with high strength and low standing effect.

[0016] The present invention also provides a method for preparing a 6-series aluminum alloy with high strength and low standing effect, comprising the following steps:

[0017] Add the prepared aluminum alloy raw materials into a melting furnace. After online refining, online degassing, and online filtering of the melt, cast the liquid aluminum alloy into an aluminum alloy ingot. Subsequently, homogenize at 400 - 500 °C for 4 - 8 h, and homogenize at 550 - 590 °C for 5 - 10 h, and cool with strong wind or water mist. Preheat the homogenized ingot to 500 °C ± 30 °C, perform extrusion production, with the quenching temperature ≥ 500 °C, and cool by water mist or water cooling. Produce profiles according to the parameters of 150 - 180 °C / 4 - 12 h or 190 - 210 °C / 2 - 8 h to obtain a 6-series aluminum alloy with high strength and low standing effect.

[0018] The present invention also provides an application of a 6-series aluminum alloy with high strength and low standing effect in automotive components.

[0019] The principle of the present invention is as follows:

[0020] In the actual production of 6xxx aluminum alloy, the waiting time after extrusion and before artificial aging is called the natural standing time. A large number of production practices have shown that the natural standing time will have an obvious positive or negative impact on the strength after artificial aging of 6xxx alloy, which is called the standing effect. When Mg + Si < 1% wt.%, the standing effect will have a positive impact on the strength after artificial aging; when Mg + Si > 1% wt.%, the standing effect will cause a significant loss in the strength after artificial aging, resulting in a negative impact. The present invention aims to prepare a high-strength alloy, and the total content of Mg + Si is far > 1 wt.%, generally having an obvious negative standing effect, which causes a lot of trouble in actual production because it requires immediate artificial aging after extrusion. In fact, it often leads to a large number of product scraps due to insufficient strength caused by failure to perform artificial aging in time.

[0021] To solve the problems caused by the aging effect in the production of high-strength products, the present invention has conducted a large number of practical explorations and finally discovered two effective rules:

[0022] 1) The Mg / Si ratio has an important influence on the aging effect. A low Mg / Si ratio has a relatively low negative aging effect;

[0023] 2) The addition of trace Sn elements can effectively reduce or even eliminate the aging effect.

[0024] Beneficial effects

[0025] By strictly limiting the Mg / Si ratio and trace Sn, the products obtained by the present invention have excellent strength and low aging effect, and have good application prospects. Detailed implementation manners

[0026] The following further elaborates the present invention in conjunction with specific embodiments. It should be understood that these embodiments are only used to illustrate the present invention and not to limit the scope of the present invention. In addition, it should be understood that after reading the content taught by the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms also fall within the scope defined by the appended claims of this application.

[0027] The preparation methods of Alloys 1-6 are the same and include the following steps:

[0028] Add the prepared aluminum alloy raw materials into a melting furnace. After online refining, online degassing, and online filtering of the melt, cast the liquid aluminum alloy into an aluminum alloy ingot; then homogenize at 550°C for 5 h and cool with strong wind or water mist; preheat the homogenized ingot to 500°C ± 30°C, perform extrusion production, and the quenching temperature is ≥500°C, and cool with water mist or water cooling; produce profiles according to the parameters of 200-210°C / 2-8 h to obtain 6-series aluminum alloys.

[0029] Table 1 Mass percentages (wt%) of alloy components in Examples 1-2 and Comparative Examples 1-4

[0030] Alloy Mg Si Mn Fe Cu Cr Sn Example 1 0.87 0.88 0.32 0.11 0.25 0.15 0.05 Example 2 0.90 1.03 0.33 0.12 0.24 0.14 0.20 Comparative example 1 1.08 0.89 0.35 0.18 0.25 0.14 0.89 Comparative example 2 1.10 0.90 0.33 0.12 0.24 0.14 0.20 Comparative example 3 0.86 0.88 0.35 0.10 0.22 0.14 ＜0.0001 Comparative example 4 0.85 0.86 0.35 0.11 0.25 0.13 0.03

[0031] Table 2 Mechanical properties of alloys in Examples 1-2 and Comparative Examples 1-4, mechanical properties after 150°C × 1000 h

[0032]

Claims

1. A 6xxx series aluminum alloy with high strength and low standing effect, characterized in that: Composed of the following components by mass percentage: Mg: 0.90%; Si: 1.03%; Cu: 0.24%; Mn: 0.33%; Cr：0.14%； Sn: 0.20%; Fe: 0.12%; Other inevitable impurity elements, the rest is Al; The preparation method of the 6-series aluminum alloy includes the following steps: Add the prepared aluminum alloy raw materials into the melting furnace. After online refining, online degassing, and online filtration of the melt, cast the liquid aluminum alloy into an aluminum alloy ingot. Then homogenize at 550 °C for 5 h and cool with strong wind or water mist. Preheat the homogenized ingot to 500 °C ± 30 °C, perform extrusion production, the quenching temperature is ≥ 500 °C, and cool by water mist or water cooling. Produce profiles according to the parameters of 200 - 210 °C / 2 - 8 h to obtain the 6-series aluminum alloy.

2. The 6xxx series aluminum alloy according to claim 1, wherein: The individual content of the inevitable impurity elements: ≤ 0.05%, the total: ≤ 0.15%.

3. A preparation method of a 6-series aluminum alloy with high strength and low parking effect as described in claim 1, including the following steps: Add the prepared aluminum alloy raw materials into the melting furnace. After online refining, online degassing, and online filtration of the melt, cast the liquid aluminum alloy into an aluminum alloy ingot. Then homogenize at 550 °C for 5 h and cool with strong wind or water mist. Preheat the homogenized ingot to 500 °C ± 30 °C, perform extrusion production, the quenching temperature is ≥ 500 °C, and cool by water mist or water cooling. Produce profiles according to the parameters of 200 - 210 °C / 2 - 8 h to obtain the 6-series aluminum alloy.

4. An application of a 6-series aluminum alloy with high strength and low parking effect as described in claim 1 in automotive parts.

Images