阅读说明：本技术 Sr、Zr、Ti三元复合微合金化Al-Si-Cu系铸造铝合金及制备方法 (Sr, Zr and Ti ternary composite microalloyed Al-Si-Cu series cast aluminum alloy and preparation method thereof ) 是由 许晓静 庄园 陈士安 骆建军 张斌 刘正 张日凯 金啸鹏 张鹏 韦宏博 于 2019-09-12 设计创作，主要内容包括：一种Sr、Zr、Ti三元复合微合金化的高强度高硬度Al-Si-Cu系铸造铝合金,其特征在于：它主要由Al、Si、Cu、Sr、Zr、Ti组成。制备方法包括：1.熔炼；2.除杂浇铸；3.均匀化退火—固溶—淬火—时效处理。本发明的Sr、Zr、Ti三元复合微合金化的Al-Si-Cu系铸造铝合金的强度为334.347~371.884 MPa、延伸率为4.3~5.25%,断口呈韧窝特征的典型韧性断裂,硬度为137.6~144.1HV,相比Al<Sub>3</Sub>Ti、A1<Sub>3</Sub>Zr单一化合物相具有更好的微合金化作用,在不降低合金铸造性能保证合金组织致密的同时高效细化了合金中的Si相和化合物相,有效提高了铸造铝合金的强度和塑性。(The Sr, Zr and Ti ternary composite microalloyed Al-Si-Cu series cast aluminum alloy is characterized by mainly comprising Al, Si, Cu, Sr, Zr and Ti, and the preparation method comprises the steps of 1, smelting, 2, impurity removal and casting, 3, homogenizing annealing, solid solution, quenching and aging treatment, wherein the strength of the Sr, Zr and Ti ternary composite microalloyed Al-Si-Cu series cast aluminum alloy is 334.347 ~ 371.884MPa, the elongation is 4.3 ~ 5.25.25%, the fracture has typical toughness fracture with dimple characteristic, the hardness is 137.6 ~ 144.1.1 HV, and compared with Al, the Al-Si-Cu series cast aluminum alloy has the characteristics of high strength, high hardness and low cost 3 Ti、A1 3 The Zr single compound phase has better microalloying effect, the Si phase and the compound phase in the alloy are efficiently refined while the compactness of the alloy structure is ensured without reducing the casting performance of the alloy, and the strength and the plasticity of the cast aluminum alloy are effectively improved.)

1. The Sr, Zr and Ti ternary composite microalloyed high-strength high-hardness Al-Si-Cu series cast aluminum alloy is characterized by mainly comprising 8.43-8.73 mass percent of silicon (Si), 5.29 ~ 5.36.36 mass percent of copper (Cu), 0.54-0.57 mass percent of strontium (Sr), 0.60-0.65 mass percent of zirconium (Zr), 0.15-0.23 mass percent of titanium (Ti) and the balance of aluminum and a small amount of impurity elements, wherein the sum of the mass percent of the components is 100%.

2. The preparation method of the Sr, Zr and Ti ternary composite microalloyed high-strength and high-hardness Al-Si-Cu series cast aluminum alloy as set forth in claim 1 is characterized in that the preparation process sequentially comprises the following steps:

(1) firstly, putting pure Al, Al-Si intermediate alloy and Al-Cu intermediate alloy into a resistance wire smelting furnace for smelting, then heating to 850 +/-10 ℃, and then sequentially adding Al-Sr intermediate alloy, Al-Zr intermediate alloy and Al-Ti-B intermediate alloy;

(2) secondly, preserving heat for 1.5 ~ 2h, adjusting the temperature to 760 +/-10 ℃ after all the intermediate alloy and metal are melted, adding hexachloroethane for primary degassing until no gas escapes, standing and preserving heat for 15min, then adding hexachloroethane for secondary degassing until no gas escapes, standing and preserving heat for 15min, removing slag, pouring into a metal mold preheated to 400 +/-10 ℃ and casting into ingots;

(3) and finally, carrying out heat treatment on the aluminum alloy ingot cast into an ingot, wherein the heat treatment is homogenizing annealing, solid solution, quenching and aging treatment, and obtaining the Sr, Zr and Ti ternary composite micro-alloyed high-strength and high-hardness Al-Si-Cu series cast aluminum alloy with the strength of 334.347 ~ 371.884MPa, the elongation of 4.3 ~ 5.25.25%, typical ductile fracture with dimple characteristic fracture and the hardness of 137.6 ~ 144.1.1 HV.

3. The method as set forth in claim 2, wherein the homogenizing annealing in the step (3) employs an annealing schedule of 250 ± 10 ℃ x 6h +350 ± 10 ℃ x 6h +450 ± 10 ℃ x 6h +480 ± 10 ℃ x 6 h.

4. The method as set forth in claim 2, wherein the solid solution in the step (3) is a solid solution having a temperature of 480 ℃ X1 h +490 ℃ X1 h.

5. The method as set forth in claim 2, wherein the quenching in the step (3) is performed with warm water of 60 ± 5 ℃.

6. The method as claimed in claim 2, wherein the aging in step (3) is carried out by furnace cooling to room temperature using an aging system of 191 ℃ for 12 hours.

7. The method as set forth in claim 2, wherein the Al-Si master alloy contains Si 16% by mass, the Al-Cu master alloy contains Cu 50.12% by mass, the Al-Sr master alloy contains Sr 9.89% by mass, the Al-Zr master alloy contains Zr 4.12% by mass, and the Al-Ti-B master alloy contains Ti 5.11% by mass.

Technical Field

The invention relates to an aluminum alloy material and a preparation method thereof, in particular to a ternary composite aluminum alloy technology, and specifically relates to a Sr, Zr and Ti ternary composite microalloyed high-strength and high-hardness Al-Si-Cu series cast aluminum alloy and a preparation method thereof.

Background

The Al-Si-Cu cast aluminum alloy has higher tensile strength and elongation, better casting performance and corrosion resistance, and is widely applied to various fields of industrial manufacturing, such as: the fields of automobiles, aerospace and the like. With the rapid increase of the number of automobiles, the continuous improvement of the automobile performance and the increasingly prominent problem of energy resources, the requirements of the automobile industry on the light weight and high strength of products are more and more strict, and the improvement of the mechanical property of the cast aluminum alloy becomes the problem which needs to be solved urgently in the current society.

It is well known that the mechanical properties of Al-Si-Cu series cast aluminum alloys are closely related to the morphology, size, and distribution of the second phase (silicon phase) in their structure.The thinning of Si phase and the reduction of the cracking of the Si phase to the matrix Al are effective ways for improving the performance of Al-Si-Cu series cast aluminum alloy. Strontium (Sr) is an effective long-acting alterant in aluminum alloy, can effectively refine Si phase in Al-Si-Cu series cast aluminum alloy and FeSiAl in the alloy₅And (3) an equivalent compound phase. Zirconium (Zr) is a 3d transition group element with strong affinity with Al, is added into the aluminum alloy, and forms A1 with Al in the process of alloy solidification₃Zr and other high-melting-point phases play a role in heterogeneous nucleation on subsequent solidification of the alloy, so that the as-cast matrix structure of the alloy is refined, the formation of fine isometric crystals is promoted, and the fluidity and the element distribution uniformity of the liquid alloy are improved. Titanium (Ti) is a commonly used additive element in aluminum alloy, and mainly plays a role in refining casting structure, reducing cracking tendency and improving mechanical properties of the material. Titanium (Ti) added to aluminum to form Al₃Ti and the melt are subjected to peritectic reaction to form a non-spontaneous core, so that the refining effect is achieved. In particular to Al formed by composite microalloying of Zr and Ti₃(Zr_x,Ti_1-x) Phase contrast Al₃Ti、A1₃The Zr single compound phase has better microalloying effect. Therefore, the Zr and Sr composite micro-alloying and the Ti alloying can greatly improve the plasticity and the toughness of the alloy without reducing the casting performance, the strength and other performances of the alloy.

So far, no Sr, Zr and Ti ternary composite microalloyed high-strength and high-hardness Al-Si-Cu series cast aluminum alloy with independent intellectual property rights and a preparation method thereof are available in China.

Disclosure of Invention

The invention aims to adjust the contents of Si and Cu elements and simultaneously add trace strontium (Sr), zirconium (Zr) and titanium (Ti) to carry out ternary composite microalloying on the basis of the component design of an Al-Si-Cu series cast aluminum alloy, efficiently refine Si phases and compound phases in the alloy without reducing the formability (fluidity) of the alloy, improve the toughness of the alloy, obtain the Al-Si-Cu series cast aluminum alloy with high strength and high hardness, and provide a preparation method thereof.

One of the technical schemes of the invention is as follows:

the Sr, Zr and Ti ternary composite microalloyed high-strength high-hardness Al-Si-Cu series cast aluminum alloy is characterized by mainly comprising 8.43-8.73 mass percent of silicon (Si), 5.29-5.29 ~ 5.36.36 mass percent of copper (Cu), 0.54-0.57 mass percent of strontium (Sr), 0.60-0.65 mass percent of zirconium (Zr), 0.15-0.23 mass percent of titanium (Ti) and the balance of aluminum and a small amount of impurity elements, wherein the sum of the mass percent of the components is 100%.

The second technical scheme of the invention is as follows:

(1) firstly, putting pure Al, Al-Si intermediate alloy and Al-Cu intermediate alloy into a resistance wire smelting furnace for melting, then heating to 850 +/-10 ℃, and then sequentially adding Al-Sr intermediate alloy, Al-Zr intermediate alloy and Al-Ti-B intermediate alloy.

(2) And secondly, preserving heat for 1.5 ~ 2h, adjusting the temperature to 760 +/-10 ℃ after all the intermediate alloy and metal are melted, adding hexachloroethane for primary degassing until no gas escapes, standing and preserving heat for 15min, then adding hexachloroethane for secondary degassing until no gas escapes, standing and preserving heat for 15min, removing slag, pouring into a metal mold preheated to 400 +/-10 ℃ and casting into ingots.

(3) And finally, carrying out homogenization annealing, solid solution, quenching and aging treatment.

The homogenization annealing in the step (3) adopts an annealing system of 250 +/-10 ℃ multiplied by 6h +350 +/-10 ℃ multiplied by 6h +450 +/-10 ℃ multiplied by 6h +480 +/-10 ℃ multiplied by 6 h;

the solid solution in the step (3) adopts a solid solution system of 480 +/-10 ℃ multiplied by 1h +490 +/-10 ℃ multiplied by 1 h;

the quenching in the step (3) adopts warm water with the temperature of 60 +/-5 ℃;

and (3) aging in the step (3) by adopting an aging system of 191 +/-10 ℃ for 12h, and cooling to room temperature along with the furnace.

The mass percent of Si in the Al-Si intermediate alloy is 16%, the mass percent of Cu in the Al-Cu intermediate alloy is 50.12%, the mass percent of Sr in the Al-Sr intermediate alloy is 9.89%, the mass percent of Zr in the Al-Zr intermediate alloy is 4.12%, and the mass percent of Ti in the Al-Ti-B intermediate alloy is 5.11%.

The invention has the beneficial effects that:

(1) on the basis of the component design of Al-Si-Cu series cast aluminum alloy, the invention carries out ternary composite microalloying by adjusting the contents of Si and Cu elements and adding trace Sr, Zr and Ti. Sr refines Si phase, Zr and Ti are compositely microalloyed to form Al₃(Zr_x,Ti_1-x) Phase contrast Al₃Ti、A1₃The Zr single compound phase has better microalloying effect. The Si phase and the compound phase in the alloy are efficiently refined while the compactness of the alloy structure is ensured without reducing the casting performance of the alloy, and the strength and the hardness of the alloy are greatly improved.

(2) The invention obtains a Sr, Zr and Ti ternary composite micro-alloyed high-strength and high-hardness Al-Si-Cu series cast aluminum alloy with the strength of 334.347 ~ 371.884MPa, the elongation of 4.3 ~ 5.25.25 percent, the fracture of which is typical ductile fracture with dimple characteristic and the hardness of which is 137.6 ~ 144.1.1 HV.

(3) The invention discloses a Sr, Zr and Ti ternary composite microalloyed high-strength and high-hardness Al-Si-Cu series cast aluminum alloy and a preparation method thereof, which break through the technical blockade of foreign high-performance aluminum alloys to a certain extent and can meet the requirements of China on high-strength and high-hardness cast aluminum alloys.

Drawings

FIG. 1 is a scanning electron microscope photograph of the metallographic structure of a ternary complex microalloyed high-strength high-hardness Al-Si-Cu cast aluminum alloy according to an embodiment of the present invention.

FIG. 2 is a scanning electron micrograph of a fracture of a tensile specimen of a high-strength and high-hardness Al-Si-Cu-based cast aluminum alloy microalloyed by ternary composition according to an embodiment of the present invention.

FIG. 3 is a scanning electron micrograph of the metallographic structure of an Sr/Zr binary micro-alloyed Al-Si-Cu cast aluminum alloy to which Ti was not added according to comparative example of the present invention.

FIG. 4 is a scanning electron micrograph of a fracture of a tensile specimen of a Sr, Zr binary micro-alloyed Al-Si-Cu based cast aluminum alloy to which Ti was not added according to comparative example of the present invention.

FIG. 5 is a scanning electron microscope photomicrograph showing the metallographic structure of an Sr/Zr binary micro-alloyed Al-Si-Cu cast aluminum alloy to which Ti was not added according to a comparative example of the present invention.

FIG. 6 is a scanning electron micrograph of a fracture of a tensile specimen of an Sr, Zr binary micro-alloyed Al-Si-Cu based cast aluminum alloy to which Ti was not added according to a comparative example of the present invention.

Detailed Description

The following detailed description of the present invention will be made with reference to the accompanying drawings and examples, but the present invention is not limited to the examples. In the master alloy used in this example, the mass percentage of Si in the Al-Si master alloy is 16%, the mass percentage of Cu in the Al-Cu master alloy is 50.12%, the mass percentage of Sr in the Al-Sr master alloy is 9.89%, the mass percentage of Zr in the Al-Zr master alloy is 4.12%, and the mass percentage of Ti in the Al-Ti-B master alloy is 5.11%.