阅读说明：本技术 一种再生铝合金及其制备方法 (Regenerated aluminum alloy and preparation method thereof ) 是由 张素卿 孙翠翠 周吉学 马百常 庄海华 宋晓村 王美芳 吴建华 于 2020-06-19 设计创作，主要内容包括：本发明属于铝合金领域,涉及一种再生铝合金及其制备方法。再生铝合金成分主要包括：Si 6.5～17％,Fe 1～5％,Mn 0.5～1.5％,杂质元素0～1％,余量的Al。再生铝合金的制备方法：将废旧铝材熔化,通过添加Al-Fe,Al-Si,Al-Mn等中间合金及纯Al调节铝液成分来达到成分要求,经精炼、保温后,浇注,对熔体施加机械振动,待温度降至半固态温度区间时,进行流变挤压铸造,最终获得一种再生铝合金。本发明通过机械振动、流变挤压铸造,制备了一种综合性能好,可保级利用的再生铝合金,制备方法具有工艺简单,成本低等优点。(The invention belongs to the field of aluminum alloy, and relates to a regenerated aluminum alloy and a preparation method thereof. The regenerated aluminum alloy mainly comprises the following components: 6.5-17% of Si, 1-5% of Fe, 0.5-1.5% of Mn, 0-1% of impurity elements and the balance of Al. The preparation method of the recycled aluminum alloy comprises the following steps: melting waste aluminum materials, adjusting the components of aluminum liquid by adding intermediate alloys such as Al-Fe, Al-Si, Al-Mn and the like and pure Al to meet the component requirements, refining, preserving heat, pouring, applying mechanical vibration to a melt, and performing rheo-extrusion casting when the temperature is reduced to a semi-solid temperature range to finally obtain the regenerated aluminum alloy. The invention prepares a recycled aluminum alloy with good comprehensive performance and guaranteed utilization through mechanical vibration and rheo-extrusion casting, and the preparation method has the advantages of simple process, low cost and the like.)

1. The secondary aluminum alloy is characterized by comprising the following chemical components in percentage by mass: 6.5-17% of Si, 1-5% of Fe, 0.5-1.5% of Mn, and the balance of Al and inevitable impurities.

2. The secondary aluminum alloy according to claim 1, which comprises the following chemical components in percentage by mass: 6.5-11.5% of Si, 1-3% of Fe, 0.5-1% of Mn, and the balance of Al and inevitable impurities.

3. The secondary aluminum alloy according to claim 1, which comprises the following chemical components in percentage by mass: 11.5-17% of Si, 3-5% of Fe, 1-1.5% of Mn, and the balance of Al and inevitable impurities.

4. A preparation method of a recycled aluminum alloy is characterized by comprising the following steps:

melting the waste aluminum material, adding intermediate alloy and pure Al into the waste aluminum material to enable the chemical composition of the waste aluminum material to reach the target content, and refining, preserving heat and stirring the waste aluminum material after the waste aluminum material is uniformly melted;

applying mechanical vibration in the solidification and cooling process, and cooling to a semi-solid temperature range for rheo-extrusion casting;

the target content is that the secondary aluminum alloy consists of the following chemical components in percentage by mass: 6.5-17% of Si, 1-5% of Fe, 0.5-1.5% of Mn, and the balance of Al and inevitable impurities.

5. The method for producing a recycled aluminum alloy as claimed in claim 1, wherein the master alloy is one or more of Al-Fe, Al-Si, and Al-Mn;

or the preheating temperature of the intermediate alloy and the pure Al is 200-220 ℃, and the preheating time is 20-30 min.

6. The method for preparing recycled aluminum alloy as claimed in claim 4, wherein the melt is kept warm for 30min after the raw materials are all melted, and the alloy melt is stirred during the keeping warm process.

7. The method for producing a recycled aluminum alloy as claimed in claim 4, wherein the solidification cooling is performed until the melt temperature is 600 to 700 ℃, the mechanical vibration is applied, and the vibration is continued while maintaining the temperature until the melt temperature is lowered to 20 to 100 ℃ above the solidus temperature.

8. The method for producing a recycled aluminum alloy as claimed in claim 4, wherein the mechanical vibration has a frequency of 10 to 60Hz, an amplitude of 0.1 to 1.0mm, and a vibration time of 1 to 20 min;

or the preheating temperature of the vibration sample cup is 500-600 ℃.

9. The method for producing a recycled aluminum alloy as claimed in claim 4, wherein the casting temperature in the rheo-extrusion casting is 570 to 630 ℃, the injection specific pressure is 100 to 200MPa, the extrusion speed is 1 to 2m/s, and the pressure holding time is 10 to 60 s.

10. The method for preparing the recycled aluminum alloy as claimed in claim 4, wherein the preheating temperature of the rheo-extrusion casting die is 150-250 ℃, the preheating temperature is kept until the rheo-extrusion casting is finished, and the obtained recycled aluminum material is air-cooled to room temperature.

Technical Field

The invention belongs to the technical field of aluminum alloy, and particularly relates to a regenerated aluminum alloy and a preparation method thereof.

Background

The information in this background section is only for enhancement of understanding of the general background of the invention and is not necessarily to be construed as an admission or any form of suggestion that this information forms the prior art that is already known to a person of ordinary skill in the art.

The aluminum alloy has the advantages of low density, high strength, good plasticity, excellent heat conductivity, electric conductivity, corrosion resistance and the like, so that the aluminum alloy is widely applied to various fields of aerospace, transportation, buildings, automobiles and the like. With the rapid development of economy, the consumption of aluminum alloy is increased year by year, and the aluminum alloy becomes the second largest metal material next to steel. Under the large environment that the energy is increasingly in shortage and the environmental protection policy is increasingly strict, the recycling of the aluminum alloy is greatly promoted.

Leftover materials, scrapped products and waste products after the end of service life generated in the manufacturing of aluminum and aluminum alloy products are collectively called waste aluminum scraps, and the waste aluminum scraps comprise process leftover materials, scrapped automobiles, waste ring-pull cans, waste aluminum alloy doors and windows and the like. The waste aluminum impurities are wide in source, high in impurity content and the like, so that the problems that the recycled aluminum alloy product is degraded in use, low in added value and the like are caused, and the waste of resource and energy is generated. Therefore, it is an urgent need for those skilled in the art to improve the comprehensive properties of the secondary aluminum alloy and achieve the guaranteed utilization thereof.

The regenerated aluminum alloy has large crystal grains, segregation of components, casting defects such as air holes, shrinkage porosity and the like, and the alloy performance is seriously influenced, so that the rejection rate of the material is higher. In addition, Fe element has been considered as the most harmful impurity element in aluminum alloys, and the content gradually increases as the number of life cycles of secondary aluminum increases. Because the solid solubility of Fe in aluminum is only 0.05 wt.%, most of Fe forms a thick, long and narrow needle-shaped brittle Fe-rich phase in an aluminum matrix, and a severe cutting effect is generated on the aluminum alloy matrix, so that the plasticity, toughness and the like of the aluminum alloy product are obviously reduced.

Disclosure of Invention

In order to overcome the problems, the invention provides a regenerated aluminum alloy with good comprehensive performance, which has excellent comprehensive mechanical properties, higher strength, no precious metal, low cost and better economic benefit.

In order to achieve the technical purpose, the invention adopts the following technical scheme:

the invention provides a regenerated aluminum alloy, which comprises the following chemical components in percentage by mass: 6.5-17% of Si, 1-5% of Fe, 0.5-1.5% of Mn, and the balance of Al and inevitable impurities.

The element Si is usually used as a basic element in the aluminum alloy, and the fluidity and the corrosion resistance of the aluminum alloy can be greatly improved by adding a proper amount of Si. The Fe element is added, and when the formed Fe-rich compound is in the forms of Chinese characters, branches and the like, the Fe-rich compound is often used as a matrix strengthening phase, so that the wear resistance, the high-temperature performance and the mechanical property of the alloy can be improved. The addition of Mn can effectively improve the appearance of the Fe-rich phase, the Mn element is similar to the Fe element in atomic size and is easy to form a replacement solid solution with Fe, the Mn element is added into the Fe-containing Al-Si alloy to replace Fe in the Fe-rich phase, and the crystal structure and the dominant growth orientation of the Fe-rich phase are changed, so that the acicular Fe-rich phase is eliminated.

In a second aspect of the present invention, there is provided a method for producing a recycled aluminum alloy, comprising:

melting the waste aluminum material, adding intermediate alloy and pure Al into the waste aluminum material to enable the chemical composition of the waste aluminum material to reach the target content, and refining, preserving heat and stirring the waste aluminum material after the waste aluminum material is uniformly melted;

applying mechanical vibration in the solidification and cooling process, and cooling to a semi-solid temperature range for rheo-extrusion casting;

the target content is that the secondary aluminum alloy consists of the following chemical components in percentage by mass: 6.5-17% of Si, 1-5% of Fe, 0.5-1.5% of Mn, and the balance of Al and inevitable impurities.

The method applies mechanical vibration in the process of solidifying and cooling the melt, the mechanical vibration promotes nucleation of the metal liquid, breaks dendritic crystals (grain refinement), reduces alloy segregation (homogenized structure), promotes separation and floating of slag gas (degassing and impurity removal, melt purification), enhances feeding of the metal liquid (density improvement) and the like, and simultaneously influences the shape, size and distribution of a second phase in the alloy, so that the metallographic structure of the casting is improved, and the comprehensive performance of the casting is improved.

Meanwhile, rheologic extrusion casting is adopted when the melt is cooled to a semi-solid temperature range. The rheo-extrusion casting forming process integrates the dual advantages of extrusion casting and semi-solid processing techniques. The viscosity of the semi-solid metal is higher than that of the liquid metal, and the semi-solid metal is filled in a laminar flow mode, so that the entrainment of gas can be reduced and even eliminated, the gas inclusion is reduced, and the porosity is reduced. The semi-solid metal already contains a certain fraction of solid phase spherical particles during casting, so that the probability of shrinkage cavity and shrinkage porosity can be reduced. The squeeze casting is solidified under higher pressure and generates plastic deformation, so that the micro shrinkage porosity and macro shrinkage cavity can be effectively reduced, the crystal grains can be refined, and the surface quality of the alloy can be improved.

The invention has the beneficial effects that:

(1) the invention provides a regenerated aluminum alloy material, which can realize the guaranteed utilization of regenerated aluminum alloy, has excellent comprehensive mechanical property, tensile strength of 363MPa and elongation of 2.45 percent, and has strength superior to that of the conventional common regenerated aluminum alloy.

(2) The invention adopts a new casting technology, namely mechanical vibration and rheo-extrusion casting. The method is characterized in that the semisolid slurry is prepared under the optimal mechanical vibration condition, and then rheo-extrusion casting is carried out.

(3) The casting technology of the invention can effectively refine the size distribution of the secondary aluminum alloy grains and the second phase, and unnecessary impurities are introduced without adding excessive alloy elements.

(4) The preparation method of the regenerated aluminum alloy is simple, short in flow, low in energy consumption and low in cost, and the regenerated aluminum alloy with excellent comprehensive performance can be obtained without special equipment.

(5) The method is simple, low in cost, strong in practicability and easy to popularize.

Drawings

The accompanying drawings, which are incorporated in and constitute a part of this specification, are included to provide a further understanding of the invention, and are incorporated in and constitute a part of this specification, illustrate exemplary embodiments of the invention and together with the description serve to explain the invention and not to limit the invention.

FIG. 1 is a photograph of the metallographic structure of the alloy of example 1 of the invention (a) the microstructure of a gravity cast alloy; (b) mechanical vibration + rheo-extrusion casting of the alloy microstructure.

Detailed Description

It is to be understood that the following detailed description is exemplary and is intended to provide further explanation of the invention as claimed. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs.

It is noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of exemplary embodiments according to the invention. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, and it should be understood that when the terms "comprises" and/or "comprising" are used in this specification, they specify the presence of stated features, steps, operations, devices, components, and/or combinations thereof, unless the context clearly indicates otherwise.

Interpretation of terms

In the present application, pure Al, Al-10Fe, Al-10Mn, and Al-30Si are all in terms of mass fraction.

A secondary aluminum alloy comprises the following chemical components in percentage by mass: 6.5-17% of Si, 1-5% of Fe, 0.5-1.5% of Mnand the balance of Al and inevitable impurities.

The preparation method of the regenerated aluminum alloy is innovative, simple in process and short in preparation flow, and comprises the following steps: smelting, mechanical vibration and rheo-extrusion casting.

In some embodiments, the waste aluminum material is melted, the components of the aluminum melt are adjusted according to the content requirements of the Si, the Fe and the Mn, and then Al-Fe, Al-Si, Al-Mn intermediate alloy and pure Al are added according to the proportion. After the raw materials are all melted, refining, preserving heat and stirring the melt. The Fe-rich phase has the characteristics of high hardness, good thermal stability and the like, so that the wear resistance and the heat resistance of the alloy can be greatly improved, and the appearance and the size of the Fe-rich phase can be improved to be beneficial.

In some embodiments, the preheating temperature of the pure Al, Al-Fe, Al-Si and Al-Mn intermediate alloy is 200-220 ℃ and the preheating time is 20-30 min.

In some embodiments, the alloy melt is poured into a vibration sample cup when the temperature is reduced to 600-700 ℃. The preheating temperature of the vibration sample cup is 500-600 ℃.

In some embodiments, mechanical vibration is applied to the melt during solidification and cooling, and the melt is kept at the temperature 20-100 ℃ above the solidus temperature and continuously vibrated. Under the mechanical vibration condition, because the temperature of vibration appearance cup wall is less than the liquid phase temperature of fuse-element and produces the subcooling, form a large amount of crystal nuclei, the fuse-element convection current that the vibration produced simultaneously makes the crystal nuclei on the cup wall drop free, gets into inside the fuse-element, and temperature fluctuation and convection current will make free crystal nuclei take place to proliferate in the fuse-element that arouses by the vibration. The vibration brings the melt with higher temperature inside to the surface and the cup wall, and the overcooling is generated to form crystal nucleus. In addition, convection exacerbates structural and energy fluctuations within the melt, greatly increasing the probability of cluster aggregation into nuclei. The convection generated by mechanical vibration enables crystal nuclei generated by supercooling to be dissociated in the whole melt, so that the growth heat transfer and mass transfer states in all directions tend to be consistent, and the generation of dendrites is inhibited; on the other hand, due to the action of convection and crystal nucleus movement, the concentration gradient and the temperature gradient of the front edge of the crystal grain are changed, so that the overcooling of the components of the front edge of the crystal grain is reduced, and the growth of dendrites is inhibited. In addition, mechanical vibration is applied in the alloy solidification process, slag gas separation and floating can be promoted, metal liquid feeding is enhanced, and the like, macroscopic and microscopic defects of castings are reduced, and the quality of the castings is improved. Meanwhile, the mechanical vibration has certain influence on the form, size and distribution of the second phase in the alloy. Therefore, the mechanical vibration can effectively refine alloy grains, improve the second phase in the alloy and improve the quality of a casting, thereby improving the performance of the alloy, and the method is a simple and effective process method.

In some embodiments, the mechanical vibration has a vibration frequency of 10 to 60Hz, an amplitude of 0.1 to 1.0mm, and a vibration time of 1 to 20 min. Wherein the vibration time is the vibration time in the alloy heat preservation process.

In some embodiments, the melt is cast into an extrusion die and allowed to air cool to room temperature after rheo-casting.

The rheo-squeeze casting forming process combines the dual advantages of squeeze casting and semi-solid processing techniques. Because the extrusion casting is solidified under higher pressure, the workpiece also generates certain plastic deformation, so that the micro shrinkage porosity and macro shrinkage cavity in the casting can be effectively eliminated, the alloy crystal grains can be effectively refined, and the casting has good mechanical property and surface quality. In addition, the extrusion casting technology is an efficient and accurate forming technology, riser feeding is not needed, the process is simple, and the metal utilization rate is high. The semi-solid processing temperature is lower than that of the liquid state, the solidification shrinkage is small, so that the casting porosity is less (or no), the mold filling is stable, the air hole defect and the oxide inclusion are less (or no), and the casting quality of the alloy is improved. The lower semi-solid processing temperature is beneficial to prolonging the service life of the die and has a plurality of unique advantages of net forming, high quality, high performance, low energy consumption, low cost and the like. Therefore, mechanical vibration and rheo-extrusion casting would be a very effective process to improve the properties of recycled aluminum alloys.

In some embodiments, the pouring temperature of the rheo-extrusion casting is 570-630 ℃, the injection specific pressure is 100-200 MPa, the extrusion speed is 1-2 m/s, and the pressure maintaining time is 10-60 s.

In some embodiments, the preheating temperature of the rheo-extrusion casting die is 150-250 ℃, and the preheating temperature is kept until the rheo-extrusion casting is finished.

The present invention is described in further detail below with reference to specific examples, which are intended to be illustrative of the invention and not limiting.