CN110564992A - sr, Zr, Ti and Ce quaternary composite microalloyed Al-Si-Cu series cast aluminum alloy and preparation method thereof - Google Patents

Abstract

A high-strength and high-plasticity Al-Si-Cu cast aluminum alloy of Sr, Zr, Ti and Ce quaternary composite microalloying, mainly composed of aluminum, silicon, copper, strontium, zirconium, titanium and cerium, and a preparation method thereof , in turn including: (1) casting, (2) homogenization annealing, (3) solution treatment, (4) aging. The tensile strength of the cast aluminum alloy of the present invention is 360 MPa to 391.58 MPa, and the elongation at break is 5.75 to 7.5%. Compared with the Sr and Zr binary micro-alloying technology, the invention uses the quaternary composite micro-alloying technology, the structure is denser, the composition of the alloy is more uniform, the size and quantity of the primary silicon phase are reduced, and the cast aluminum alloy is more effectively improved. The cast aluminum alloy prepared by the invention has high tensile strength and elongation at break, and meets the requirements of the automobile industry for lightweight, high strengthening and high toughness of alloy parts.

Description

Sr, Zr, Ti and Ce quaternary composite microalloyed Al-Si-Cu cast aluminum alloy and Preparation

technical field

The invention relates to a cast aluminum alloy, in particular to an Al-Si-Cu series cast aluminum alloy, in particular to a high-strength and high-plastic Al-Si alloyed with Sr, Zr, Ti and Ce quaternary composite microalloying -Cu-based cast aluminum alloy and its preparation method.

Background technique

Cast aluminum alloys have high tensile strength and elongation, excellent casting properties and corrosion resistance, and are widely used in various fields of industrial manufacturing, such as automobiles, aerospace and other fields. With the rapid growth of the number of automobiles, the continuous improvement of automobile performance and the increasingly prominent problems of energy resources, the automobile industry has become more and more strict with the requirements of lightweight and high-strengthening products, and improving the mechanical properties of cast aluminum alloys has become an urgent need in today's society. solved problem.

Patent Application No. 201710193447.9 discloses a preparation method of high-strength cast aluminum alloy. The obtained alloy has high strength and hardness, and good wear resistance and corrosion resistance, but the alloy uses centrifugal casting, and the production cost is relatively high; patent application No. 201611031488.X discloses the 2A12 aluminum alloy casting process, and the obtained workpiece has a low tensile strength; Patent Application No. 201010607633.0 discloses a high-strength cast aluminum alloy, and the obtained alloy has a high room temperature tensile strength, but a low elongation at break. So far, there has not been a cast aluminum alloy whose strength and plasticity fully meet the requirements of use on the market. Adding an appropriate amount of trace elements to the alloy can improve the performance of the aluminum alloy. Based on the design idea of "multi-element and small amount" of micro-alloying, the present invention proposes a quaternary composite micro-alloying technology.

As a modifier, Sr mainly exists as Al ₄ Sr in the alloy liquid. This compound is unstable and easy to decompose, and cannot play a role in non-uniform nucleation. It is ineffective for refining primary silicon, but free Sr is adsorbed on the surface of growing Si. , preventing eutectic silicon from growing in a sheet-like manner. The addition of Ce can form CeO ₂ , and CeO ₂ can act as a heterogeneous nucleation core of eutectic silicon. Therefore, the simultaneous addition of Sr and Ce achieves the effect of compound modification. Even if the nucleation rate of eutectic silicon is increased, the growth form of eutectic silicon is changed to be fragmented into fine dots. Therefore, the addition of Sr and Ce at the same time can better refine the structure, make the structure more dense, and reduce the size and quantity of the primary silicon phase, and more effectively improve the performance of the aluminum alloy.

Zr element is added to the aluminum alloy, during the solidification process of the alloy, Zr element and Al form high melting point phases such as A1 ₃ Zr, which play a heterogeneous nucleation effect on the subsequent solidification of the alloy, refine the as-cast matrix structure, and improve the liquid state. Alloy fluidity and element distribution uniformity. Ti is also a commonly used trace element in aluminum alloys. After adding Ti, it can form Al ₃ Ti phase in the aluminum alloy, forming a non-spontaneous core during crystallization, which significantly refines the casting structure. The Al ₃ Zr _x T _1-x phase formed when Zr and Ti are added at the same time can better refine the structure and has a better refining effect than the single A1 ₃ Zr phase and Al ₃ Ti phase. Zr and Ti have better strengthening effect than only Zr or only Ti.

To date, there are no cast aluminum alloys fortified using quaternary composite microalloying of Sr, Zr, Ti and Ce on the market. In order to solve the problems of low tensile strength and low plasticity of cast aluminum alloys in the prior art, it is urgent to invent a high-strength and high-plasticity Al-Si-Cu system with Sr, Zr, Ti and Ce quaternary composite microalloying Cast aluminum alloy and preparation method thereof.

SUMMARY OF THE INVENTION

The purpose of the present invention is to aim at the deficiencies existing in the existing cast aluminum alloys, using Sr, Zr, Ti and Ce quaternary composite microalloying technology (using Sr, Ce composite modification effect, using Zr, Ti composite formed Al ₃ Zr _x T _1-x phase), proposed a high-strength and high-plastic Al-Si-Cu cast aluminum alloy with Sr, Zr, Ti and Ce quaternary composite microalloying and its preparation method, which solved the problem of tensile strength of cast aluminum alloy. The problem of low strength and poor plasticity.

One of the technical solutions of the present invention is:

A high-strength and high-plastic Al-Si-Cu cast aluminum alloy with Sr, Zr, Ti and Ce quaternary composite microalloying, characterized in that it is mainly composed of aluminum (Al), silicon (Si), copper (Cu) , strontium (Sr), zirconium (Zr), titanium (Ti) and cerium (Ce), wherein the mass percentage of silicon (Si) is 7.5~11.16%, and the mass percentage of copper (Cu) is 4.34~5.31%, The mass percent of strontium (Sr) is 0.55~0.7%, the mass percent of zirconium (Zr) is 0.42~0.59%, the mass percent of titanium (Ti) is 0.14~0.18%, and the mass percent of cerium (Ce) is 0.15~0.23 %, the rest are aluminum and inevitable impurity elements; the sum of each component is 100%.

The second technical scheme of the present invention is:

A method for preparing a high-strength and high-plastic Al-Si-Cu cast aluminum alloy by quaternary composite microalloying of Sr, Zr, Ti and Ce, characterized in that the method comprises the following steps: (1) melting and casting, (2) homogeneous Chemical annealing, (3) solution treatment, (4) aging;

The melting and casting refers to: after the Al, Al-Si master alloy and Al-Cu master alloy are melted, the temperature is raised to 850±10°C, and then Al-Sr master alloy, Al-Zr master alloy, Al-Ti- B master alloy and Al-Ce master alloy, after all master alloys and metals are melted, keep the temperature for 2-2.5 hours, reduce the temperature to 750-780 ℃, add hexachloroethane refining agent for refining, let stand for 10 min after refining, After standing, remove slag, add hexachloroethane refining agent again for refining, let stand for 10 min after refining, remove slag after standing, and cast into ingots;

The homogenization annealing refers to: 250±10℃×6h+350±10℃×6h+450±10℃×6h+

480±10℃×20h;

The solution treatment refers to 480±10℃×1h+490±10℃×1h, and then water quenching at room temperature;

The aging period refers to: 191±10℃×12h;

The quaternary composite microalloying of Sr, Zr, Ti and Ce can be obtained by the above four-step method, and the quaternary composite microalloying of Sr, Zr, Ti and Ce can be obtained. High strength and high plasticity Al-Si-Cu cast aluminum alloy with elongation of 5.75~%7.5%.

The mass percentage of Si in the Al-Si master alloy is 17%, 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%, and the Al-Zr master alloy is 9.89%. The mass percentage of Zr in the Al-Ti-B master alloy is 4.11%, the mass percentage of Ti in the Al-Ti-B master alloy is 5.11%, and the mass percentage of Ce in the Al-Ce master alloy is 10%.

The present invention has the following beneficial effects:

(1) Using the quaternary composite microalloying technology, the simultaneous addition of Sr and Ce has a composite modification effect, the structure is denser, the alloy composition is more uniform, the number and size of the primary silicon phase are reduced, and the aluminum alloy is more effectively improved. performance; the Al ₃ Zr _x T _1-x phase formed by the addition of Zr and Ti at the same time can better refine the structure, and has a better refining effect than the single A1 ₃ Zr phase and Al ₃ Ti phase, and is more effective. The strength and plasticity of the cast aluminum alloy are improved.

(2) The cast aluminum alloy prepared by the present invention has high tensile strength and elongation at break, and meets the requirements of the automobile industry for lightweight, high strengthening and high toughness of alloy parts.

Description of drawings

FIG. 1 is a SEM image of the tensile fracture of the quaternary composite microalloyed Al-Si-Cu cast aluminum alloy in Example 1 of the present invention.

FIG. 2 is an SEM image of the surface of the quaternary composite microalloyed Al-Si-Cu cast aluminum alloy in Example 1 of the present invention.

Fig. 3 is the SEM image of the tensile fracture of the Al-Si-Cu cast aluminum alloy in Example 2 of the present invention;

4 is an SEM image of the surface of the quaternary composite microalloyed Al-Si-Cu cast aluminum alloy in Example 1 of the present invention.

5 is a SEM image of a tensile fracture of the quaternary composite microalloyed Al-Si-Cu based cast aluminum alloy of Comparative Example 1 of the present invention.

FIG. 6 is a SEM image of the surface of the quaternary composite microalloyed Al-Si-Cu cast aluminum alloy in Example 1 of the present invention.

7 is a SEM image of the tensile fracture of the quaternary composite microalloyed Al-Si-Cu based cast aluminum alloy of Comparative Example 2 of the present invention.

8 is a SEM image of the surface of the quaternary composite microalloyed Al-Si-Cu based cast aluminum alloy of Example 1 of the present invention.

Detailed ways

The present invention will be further described below in conjunction with specific embodiments.

Example 1.

A Sr, Zr, Ti and Ce quaternary composite micro-alloyed Al-Si-Cu cast aluminum alloy with high strength and high plasticity is prepared by the following method:

First, after melting the Al, Al-Si master alloy and Al-Cu master alloy, the temperature was raised to 850±10°C, and Al-Sr master alloy, Al-Zr master alloy, Al-Ti-B master alloy, Al- Ce master alloy, after all the master alloys and metals are melted, keep the temperature for 2-2.5 hours, reduce the temperature to 750-780 ℃, add hexachloroethane refining agent for refining, let stand for 10 minutes after refining, remove slag after standing, and then again Add hexachloroethane refining agent for refining, let stand for 10 minutes after refining, remove slag after standing, and cast into ingots.

Secondly, the aluminum alloy ingot is subjected to homogenization annealing, and the homogenization annealing process is as follows:

250±10℃×6h+350±10℃×6h+450±10℃×6h+480±10℃×20h;

Third, carry out solution treatment again, the solution treatment process is 480±10℃×1h+490±10℃×1h, and water quenching at room temperature;

Finally, an aging treatment of 191±10℃×12h is carried out to obtain a high-strength and high-plastic Al-Si-Cu cast aluminum alloy with quaternary composite microalloying of Sr, Zr, Ti and Ce.

The actual composition of the aluminum alloy of this embodiment measured by EDS is: Si11.16%, Cu4.34%, Sr0.70%, Zr0.42%, Ti0.14%, Ce0.19%, the balance is aluminum and unavoidable impurity elements.

The tensile strength of the aluminum alloy of this example is 391.58 MPa, and the elongation at break is 5.75%. With reference to Figure 1, it can be seen that the aluminum alloy of this embodiment has many tear edges, the structure is very uniform and dense, and there is no obvious porosity (shrinkage); the primary silicon phase is very small, and it is almost completely dissolved, so the alloy has very high strength. and plasticity.

Example 2.

A high-strength and high-plasticity Al-Si-Cu based cast aluminum alloy with Sr, Zr, Ti and Ce quaternary composite microalloying, the preparation method is the same as that of Example 1.

The actual composition of the aluminum alloy of this embodiment measured by EDS is: Si 7.66%, Cu 4.84%, Sr 0.57%, Zr 0.59%, Ti 0.16%, Ce 0.15%, and the balance is aluminum and inevitable impurity elements.

The tensile strength of the aluminum alloy of this example is 368 MPa, and the elongation at break is 7.5%. With reference to Figure 2, it can be seen that the aluminum alloy of this embodiment has many tear edges, the structure is dense and uniform, and the porosity (shrinkage) is very small; the primary silicon phase is very small, and the size is small, so the alloy has high strength and Very good plasticity.

Example 3.

A high-strength and high-plasticity Al-Si-Cu based cast aluminum alloy with Sr, Zr, Ti and Ce quaternary composite microalloying, the preparation method is the same as that of Example 1.

The actual composition of the aluminum alloy of this embodiment measured by EDS is: Si7.5%, Cu5.31%, Sr0.55%, Zr0.46%, Ti0.18%, Ce0.23%, the balance is aluminum and unavoidable impurity elements.

The tensile strength of the aluminum alloy of this example is 360 MPa, and the elongation at break is 7.25%.

Comparative Example 1.

An Al-Si-Cu based cast aluminum alloy added with Sr and Zr. The preparation method of the aluminum alloy of this comparative example is the same as that of Example 1.

The actual composition of the aluminum alloy of this embodiment measured by EDS is: Si7.39%, Cu4.9%, Sr0.54%, Zr0.36%, and the balance is aluminum and inevitable impurity elements.

The tensile strength of the aluminum alloy of this comparative example was 218.97 MPa, and the elongation at break was 3.25%. Combining with Fig. 3, it can be seen that the aluminum alloy of this comparative example has less tear edges, more porosity (shrinkage porosity), and the structure is not dense enough; the primary silicon is relatively large, and the size is very large, so it has lower strength and higher density. poor plasticity.

Comparative Example 2.

An Al-Si-Cu based cast aluminum alloy added with Sr and Zr. The preparation method of the aluminum alloy of this comparative example is the same as that of Example 1.

The actual composition of the aluminum alloy of this embodiment measured by EDS is: Si7.21%, Cu4.98%, Sr0.51%, Zr0.33%, and the balance is aluminum and inevitable impurity elements.

The tensile strength of the aluminum alloy of this comparative example is 208.84 MPa, and the elongation at break is 5%. Combining with Figure 3, it can be seen that the aluminum alloy of this comparative example has few tear edges, obvious porosity (shrinkage porosity), and the number is large, and the structure is not dense; the primary silicon phase is many, and the size is large, so it has a very low strength and plasticity.

Comparative Example 3.

An Al-Si-Cu based cast aluminum alloy added with Sr and Zr. The preparation method of the aluminum alloy of this comparative example is the same as that of Example 1.

The actual composition of the aluminum alloy of this embodiment measured by EDS is: Si6.93%, Cu3.45%, Sr0.42%, Zr0.42%, and the balance is aluminum and inevitable impurity elements.

The tensile strength of the aluminum alloy of this comparative example is 300.45 MPa, and the elongation at break is 3.5%.

Comparative Example 4.

An Al-Si-Cu based cast aluminum alloy added with Sr and Zr. The preparation method of the aluminum alloy of this comparative example is the same as that of Example 1.

The actual composition of the aluminum alloy of this embodiment measured by EDS is: Si6.11%, Cu3.31%, Sr0.46%, Zr0.54%, and the balance is aluminum and inevitable impurity elements.

The tensile strength of the aluminum alloy of this comparative example is 299.69 MPa, and the elongation at break is 4%.

The invention uses the quaternary microalloying technology to prepare a high-strength and high-plasticity Al-Si-Cu cast aluminum alloy with Sr, Zr, Ti and Ce quaternary composite microalloying, and the tensile strength is 360MPa-391.58MPa, Compared with Sr, Zr binary alloyed Al-Si-Cu cast aluminum alloy, the maximum increase is 182.74MPa; the elongation at break is 5.75~%7.5%, compared with Sr, Zr binary alloyed Al-Si-Cu alloy The maximum increase of 4.25% for cast aluminum alloys.

The specific embodiments of the present invention have been described above. It should be understood that the present invention is not limited to the above-mentioned special embodiments, and those skilled in the art can make modifications and modifications within the scope of the claims, which do not affect the essence of the present invention. .

The parts not involved in the present invention are the same as or can be implemented by using the prior art.

Claims (3)

1. the Sr, Zr, Ti and Ce quaternary composite microalloyed high ~ strength high ~ plasticity Al ~ Si ~ Cu series cast aluminum alloy is characterized by mainly comprising 7.5 ~ 11.16% of silicon (Si), 4.34 ~ 5.31% of copper (Cu), 0.55 ~ 0.7% of strontium (Sr), 0.42 ~ 0.59% of zirconium (Zr), 0.14 ~ 0.18% of titanium (Ti), 0.15 ~ 0.23% of cerium (Ce) and the balance of aluminum and inevitable impurity elements, wherein the sum of the components is 100%.

2. the preparation method of the Sr, Zr, Ti and Ce quaternary composite microalloyed high-strength and high-plasticity Al-Si-Cu series cast aluminum alloy of claim 1 is characterized by sequentially comprising the following steps of: (1) casting, (2) homogenizing annealing, (3) solution treatment, and (4) aging;

The fusion casting is as follows: heating to 850 +/-10 ℃ after Al, Al-Si intermediate alloy and Al-Cu intermediate alloy are melted, sequentially adding Al-Sr intermediate alloy, Al-Zr intermediate alloy, Al-Ti-B intermediate alloy and Al-Ce intermediate alloy, preserving heat for 2-2.5 hours after all intermediate alloy and metal are melted, reducing the temperature to 750-780 ℃, adding a hexachloroethane refining agent for refining, standing for 10min after refining, removing slag after standing, adding the hexachloroethane refining agent again for refining, standing for 10min after refining, removing slag after standing, and casting into ingots;

The homogenizing annealing refers to the following steps: 250 plus or minus 10 ℃ multiplied by 6h +350 plus or minus 10 ℃ multiplied by 6h +450 plus or minus 10 ℃ multiplied by 6h +

480±10℃×20h；

The solid solution treatment is 480 +/-10 ℃ multiplied by 1h +490 +/-10 ℃ multiplied by 1h, and then water quenching is carried out at room temperature;

The aging refers to: 191 plus or minus 10 ℃ multiplied by 12 hours;

the high ~ strength and high ~ plasticity Al ~ Si ~ Cu series cast aluminum alloy with Sr, Zr, Ti and Ce quaternary compound microalloying, the tensile strength of 360MPa ~ 391.58MPa and the elongation at break of 5.75 ~ 7.5 percent can be obtained.

3. The method as set forth in claim 2, wherein the Al-Si master alloy contains Si 17% 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 4.11% by mass, the Al-Ti-B master alloy contains Ti 5.11% by mass, and the Al-Ce master alloy contains Ce 10% by mass.