CN106756342B - A kind of heat-treatable strengthened high strength high toughness casting aluminum alloy and preparation method - Google Patents

Abstract

The invention discloses a high-strength and high-toughness cast aluminum alloy that can be strengthened by heat treatment. The alloy is composed of the following components by weight percentage: Cu 3.8 wt% to 4.6 wt%; Zn 2.5 wt% to 3.5 wt%; Mg 0.25 wt% %~0.5 wt%; Mn 0.25 wt%~0.5 wt%; Ti 0.02 wt%~0.35 wt%; Dy 0.15wt%~0.45 wt%. When the element addition content ratio reaches M(Cu):M(Zn):M(Mg)=(15-20):(8-15):(1-3), after three-stage aging (160℃/2.5~4h +180°C/5~8.0h+210°C/1.5~3h), the main strengthening phases θ'(Al ₂ Cu), T'(Al ₁₂ CuMn ₂ ) and S'(Al ₂ CuMg) can be precipitated in turn, respectively, With the increase of aging temperature and time, the precipitation strengthening phase can gradually coarsen. Adding 0.15wt%~0.45wt% of rare earth element Dy can effectively inhibit the growth and coarsening of the three precipitation strengthening phases, and can better improve the strength of the alloy and resilience.

Description

A high-strength and high-toughness cast aluminum alloy that can be strengthened by heat treatment and its preparation method

technical field

The invention relates to a high-strength and high-toughness cast aluminum alloy which can be strengthened by heat treatment, in particular to a high-strength and high-toughness cast Al-Cu-Zn-Mn-Mg-Ti-Dy aluminum alloy which can be strengthened by heat treatment.

Background technique

Casting aluminum alloy is a kind of aluminum alloy product that countries in the world have invested more in research in recent years. Its advantages are small specific gravity, high specific strength, isotropic structure, good corrosion resistance and casting process, and can be used for various molding castings; moreover, cast aluminum alloy is also low in price, and the melting process and equipment are relatively simple. , Many advantages that can be produced in small batches or in large batches. Especially in the semi-solid casting process, the casting structure is dense and has less segregation, and the alloy has good fluidity, which can better add reinforcing materials. Even so, the strength and toughness of cast aluminum alloy is slightly lower than that of deformed aluminum alloy, which limits its application range. Deformed aluminum alloy reduces structural defects by means of extrusion, rolling, forging, etc. Many important uses such as special heavy-duty Deformed aluminum alloys are mostly used in vehicle road wheels and aviation aluminum alloys. However, for wrought aluminum alloys, the equipment and tooling molds require high requirements, many processes, long production cycles, and high costs.

Contents of the invention

The present invention adds a specific proportion of Zn and Mg elements to the traditional Al-Cu series cast aluminum alloy to form an Al-Cu-Zn-Mg series alloy, and the main strengthening phase formed in the alloy structure is θ(Al ₂ Cu ), T(Al ₁₂ CuMn ₂ ) and S(Al ₂ CuMg), etc., effectively improve the heat treatment strengthening effect of the alloy.

The technical scheme that the present invention takes is:

A high-strength and high-toughness cast aluminum alloy material that can be strengthened by heat treatment mainly includes the following components: Cu, Zn, Mg, and Al. The weight ratio of the three elements of Cu, Zn and Mg is: M(Cu):M(Zn):M(Mg) =(15-20):(8-15):(1-3).

As preferably, the weight percent composition of each component in the aluminum alloy material is:

Cu 3.8 wt%～4.6 wt%,

Zn 2.5wt%～3.5wt%,

Mg 0.25wt%～0.5wt%,

The balance is Al.

Further preferably, the aluminum alloy material further includes Mn element in an amount of 0.25 wt% to 0.5 wt%.

Further preferably, the aluminum alloy material further includes a rare earth element Dy in an amount of 0.15wt%-0.45wt%.

Further preferably, the aluminum alloy material further includes Ti element in an amount of 0.02 wt% to 0.35 wt%.

A high-strength and high-toughness cast aluminum alloy material that can be strengthened by heat treatment, which consists of the following components in weight percentage:

Cu 3.8 wt%～4.6 wt%,

Zn 2.5wt%～3.5wt%,

Mg 0.25wt%～0.5wt%,

Mn 0.25wt%～0.5wt%,

Ti 0.25wt%～0.35wt%,

Dy 0.15wt%～0.45wt%,

The balance is Al.

A method for preparing a high-strength and high-toughness cast aluminum alloy material that can be strengthened by heat treatment, comprising the following steps:

(1) Using pure Cu, Al-5%Zn master alloy, pure Mg, Al-20%Mn, Al-5%Ti master alloy and Al-10%Dy master alloy as raw materials, it can be heat treated according to the above-mentioned The ratio of each component in the reinforced high-strength and high-toughness cast aluminum alloy material is used for batching;

(2) Melting the prepared material in step (1) in a melting furnace, then pouring the alloy melt into a mold, stirring, and cooling to obtain an ingot;

(3) Perform uniform solution heat treatment on the ingot;

(4) Tertiary aging temperature/time: 160°C/2.5～4h+180°C/5～8.0h+210°C/1.5～3h.

Preferably, the melting temperature in step (2) is 740°C to 780°C.

Preferably, the uniform solid solution temperature/time in step (3) is: 500°C-530°C/20h-30h.

The beneficial effects of the present invention are:

(1) The present invention has advanced alloy design components. On the basis of the traditional Al-Cu cast aluminum alloy, the present invention adds Zn and Mg elements with strengthening effect, and controls the precipitation through different three-stage aging temperatures and times Different precipitation strengthening phases. In the present invention, the element content ratio M(Cu):M(Zn):M(Mg)=(15-20):(8-15):(1-3) can co-generate θ(Al ₂ Cu), T(Al ₁₂ CuMn ₂ ) and S(Al ₂ CuMg) strengthening phases.

(2) The present invention has a good heat treatment system, through solution temperature/time: 500℃～530℃/20h～30h, the θ(Al ₂ Cu), T(Al ₁₂ CuMn ₂ ) and S (Al ₂ CuMg) enhances phase dissolution into the matrix to reach a supersaturated solid solution, and then through three-stage aging (160°C/2.5～4h+180°C/5～8.0h+210°C/1.5～3h) can sequentially separate Corresponding to the precipitation of the main strengthening phases θ'(Al ₂ Cu), T'(Al ₁₂ CuMn ₂ ) and S'(Al ₂ CuMg), so the required strengthening phases can be selectively precipitated by controlling the aging temperature and time. Under the three-stage aging system of the present invention, the three strengthening phases can be precipitated separately, but as the temperature and time prolong, the precipitation strengthening phase will grow and coarsen, so the present invention adds rare earth elements Dy0.15wt%~ 0.45 wt%, has the effect of removing oxygen, removing hydrogen, refining and purifying the solution, effectively realizing the role of replacing precious and rare metals Ag, V, Zr, etc., adding a reasonable proportion of rare earth element Dy can generate eutectic phase Al ₃ Dy, It can promote the precipitation of θ'(Al ₂ Cu), T'(Al ₁₂ CuMn ₂ ) and S'(Al ₂ CuMg) in the GP region during the subsequent aging process, and can pin the movement of dislocations, enabling these three types of strengthening The phase maintains the size of the initial precipitation, inhibits the growth of the strengthening phase, and can significantly improve the strength of the alloy without compromising the toughness of the alloy.

The semi-solid cast aluminum alloy prepared by the composition formula and preparation method of the present invention has a tensile strength of 480-550MPa, a yield strength of 380-440MPa, and an elongation of 7.5-10%, which is suitable for strength and shaping. Highly demanding industrial fields.

Description of drawings

Figure 1 is the metallographic microstructure before and after heat treatment (A has not been heat treated; B has been heat treated);

Figure 2 is the tensile curve of the sample;

Figure 3 is the scanning diagram of the tensile fracture of the sample.

Detailed ways

The present invention adds a specific proportion of Zn and Mg elements to the traditional Al-Cu series cast aluminum alloy to form an Al-Cu-Zn-Mg series alloy, and the main strengthening phase formed in the alloy structure is θ(Al ₂ Cu ), T(Al ₁₂ CuMn ₂ ) and S(Al ₂ CuMg), etc., effectively improve the heat treatment strengthening effect of the alloy. When the Cu content in the melt is high, the L → α(Al)+θ(Al ₂ Cu)+ T (Al ₁₂ CuMn ₂ ) ternary eutectic reaction occurs at 547.5°C, and θ and T are formed as cast alloys. The main strengthening phase, when the Mg content is less than 0.05%, another main S(Al ₂ CuMg) phase can be formed at 507°C. Quantitative θ(Al ₂ Cu ), T(Al ₁₂ CuMn ₂ ) and S(Al ₂ CuMg), exceeding the content of Cu 3.8 wt%~4.6 wt%, Mg 0.25 wt%~0.5 wt% and Mn 0.25 wt%~0.5 wt%, the resulting strengthening is relatively Alloy properties have embrittlement and reduce corrosion resistance, so it is not suitable to add excessive elements. Through tertiary aging at 160℃/2.5～4h+180℃/5～8.0h+210℃/1.5～3h, θ'(Al ₂ Cu), T'(Al ₁₂ CuMn ₂ ) and If S'(Al ₂ CuMg) exceeds this aging range, it cannot play the role of heat treatment to control phase precipitation.

After the rare earth element Dy is added, the Al 3 Dy phase can spontaneously nucleate and form Al ₃ Dy phase, which can improve the strength of the alloy. In addition, as the aging temperature and time increase, the strengthening phases θ'(Al ₂ Cu), T'(Al ₁₂ CuMn ₂ ) and S'(Al ₂ CuMg) will grow and coarsen, and the added content of Dy 0.15 wt%～0.45 wt%, the movement of dislocations can be pinned, the size of these three strengthening phases can be maintained at the initial precipitation, the growth of strengthening phases can be suppressed, and the toughness of the alloy can be guaranteed without compromising the toughness of the alloy. increase the strength of the alloy.

Therefore, the content ratio of added element components M(Cu):M(Zn):M(Mg) =(15-20):(8-15):(1-3); the content of added rare earth elements Dy 0.15wt%～ 0.45 wt%, to develop a heat-treatable high-strength and high-toughness cast aluminum alloy material and preparation method that can replace part of the deformed aluminum alloy, to achieve the purpose of replacing forging with casting, shortening the manufacturing cycle, and reducing manufacturing costs, which has important theoretical significance and great significance. practical application value.

The present invention will be further described below in conjunction with the examples, but not limited thereto.

Example 1

(1) Take Cu: 3.8 wt%, Zn: 2.5 wt%, Mg: 0.25 wt%, Mn: 0.25 wt%, Ti: 0.25 wt%, Dy: 0.15 wt% according to the weight percentage of the constituent elements, and the balance is Al.

(2) The above-mentioned materials are smelted at a high temperature in a melting furnace at a temperature of 740°C until they are melted, and the alloy melt is poured into a cylindrical stainless steel mold, and then water-cooled to form an ingot;

(3) Perform uniform solution heat treatment on the ingot, uniform solution temperature/time: 500°C/20h.

(4) Tertiary aging temperature/time: 160°C/2.5h+180°C/5h+210°C/1.5h.

Example 2

(1) Take Cu: 3.9 wt%, Zn: 2.9 wt%, Mg: 0.29 wt%, Mn: 0.28 wt%, Ti: 0.28 wt%, Dy: 0.20 wt% according to the weight percentage of the constituent elements, and the balance is Al;

(2) The above-mentioned materials are smelted at a high temperature in a melting furnace at a temperature of 750°C until they are melted, and the alloy melt is poured into a cylindrical stainless steel mold, and then water-cooled to form an ingot;

(3) Perform uniform solution heat treatment on the ingot, uniform solution temperature/time: 500°C/25h.

(4) Tertiary aging temperature/time: 160°C/3.0 h+180°C/6h+210°C/2.0h.

Example 3

(1) Take Cu: 4.0 wt%, Zn: 3.1 wt%, Mg: 0.32 wt%, Mn: 0.32 wt%, Ti: 0.30 wt%, Dy: 0.25 wt% according to the weight percentage of the constituent elements, and the balance is Al;

(2) The above-mentioned materials are smelted at a high temperature in a melting furnace at a temperature of 760°C until they are melted, and the alloy melt is poured into a cylindrical stainless steel mold, and then water-cooled to form an ingot;

(3) Perform uniform solution heat treatment on the ingot, uniform solution temperature/time: 510°C/30h.

(4) Tertiary aging temperature/time: 160°C/3.5h+180°C/6.5h+210°C/2.5h.

Example 4

(1) Take Cu: 4.1 wt%, Zn: 3.3 wt%, Mg: 0.38 wt%, Mn: 0.35 wt%, Ti: 0.32 wt%, Dy: 0.30 wt% according to the weight percentage of the constituent elements, and the balance is Al;

(2) The above materials are smelted at a high temperature in a smelting furnace at a temperature of 770°C until melting, and the alloy melt is poured into a cylindrical stainless steel mold, and then water-cooled to form an ingot;

(3) Perform uniform solution heat treatment on the ingot, uniform solution temperature/time: 515°C/30h.

(4) Tertiary aging temperature/time: 160°C/4.0 h+180°C/7.0 h+210°C/3.0h.

Example 5

(1) Take Cu: 4.2 wt%, Zn: 3.5 wt%, Mg: 0.45 wt%, Mn: 0.40 wt%, Ti: 0.35 wt%, Dy: 0.35 wt% according to the weight percentage of the constituent elements, and the balance is Al.

(2) The above materials are smelted at a high temperature in a smelting furnace at a temperature of 780°C until melting, and the alloy melt is poured into a cylindrical stainless steel mold, and then water-cooled to form an ingot;

(3) Perform uniform solution heat treatment on the ingot, uniform solution temperature/time: 520°C/30h.

(4) Tertiary aging temperature/time: 160°C/3.5h+180°C/7.5h+210°C/2.5h.

Example 6

(1) According to the weight percentage of the constituent elements, Cu: 4.3 wt%, Zn: 3.5 wt%, Mg: 0.45 wt%, Mn: 0.40 wt%, Ti: 0.35 wt%, Dy: 0.35 wt%, and the balance is Al.

(2) Melting the above materials at a high temperature in a melting furnace at a temperature of 780°C until melting, pouring the alloy melt into a cylindrical stainless steel mold, and then cooling it with water to form an ingot;

(3) Perform uniform solution heat treatment on the ingot, uniform solution temperature/time: 530°C/30h.

(4) Tertiary aging temperature/time: 160°C/4.0h+180°C/8.0h+210°C/3.0h.

Example 7

(1) Cu: 0.5wt%, Zn: 0.5wt%, Mg: 0.5wt%, and Al in the balance according to the weight percentage of the constituent elements.

(2) Melting the above materials at a high temperature in a melting furnace at a temperature of 780°C until melting, pouring the alloy melt into a cylindrical stainless steel mold, and then cooling it with water to form an ingot;

(3) Perform uniform solution heat treatment on the ingot, uniform solution temperature/time: 530°C/30h.

(4) Tertiary aging temperature/time: 160°C/4.0h+180°C/8.0h+210°C/3.0h.

Example 8

(1) According to the weight percentage of the constituent elements, Cu: 2.0 wt%, Zn: 1.0 wt%, Mg: 1.0 wt%, Dy: 0.15 wt%, and the balance is Al.

(2) Melting the above materials at a high temperature in a melting furnace at a temperature of 780°C until melting, pouring the alloy melt into a cylindrical stainless steel mold, and then cooling it with water to form an ingot;

(3) Perform uniform solution heat treatment on the ingot, uniform solution temperature/time: 530°C/30h.

(4) Tertiary aging temperature/time: 150°C/7.0h+120°C/3.0h+230°C/5.0h.

Example 9

(1) Take Cu: 0.5 wt%, Zn: 0.5 wt%, Mg: 0.5 wt%, Ti: 0.28 wt%, Dy: 0.15 wt% according to the weight percentage of the constituent elements, and the balance is Al.

(2) Melting the above materials at a high temperature in a melting furnace at a temperature of 780°C until melting, pouring the alloy melt into a cylindrical stainless steel mold, and then cooling it with water to form an ingot;

(3) Perform uniform solution heat treatment on the ingot, uniform solution temperature/time: 530°C/30h.

(4) Aging temperature/time: 160°C/4.0h+180°C/8.0h+210°C/3.0h.

Example 10

(1) According to the weight percentage of the constituent elements, Cu: 3.8 wt%, Zn: 2.5 wt%, Mg: 0.25 wt%, Mn: 0.25 wt%, Ti: 0.25 wt%, Dy: 0.05 wt%, and the balance is Al.

(2) The above-mentioned materials are smelted at a high temperature in a melting furnace at a temperature of 740°C until they are melted, and the alloy melt is poured into a cylindrical stainless steel mold, and then water-cooled to form an ingot;

(3) Perform uniform solution heat treatment on the ingot, uniform solution temperature/time: 500°C/20h.

(4) Tertiary aging temperature/time: 160°C/2.5h+180°C/5h+210°C/1.5h.

Example 11

(1) Take Cu: 3.8 wt%, Zn: 2.5 wt%, Mg: 0.25 wt%, Mn: 0.25 wt%, Ti: 0.25 wt%, Dy: 0.15 wt% according to the weight percentage of the constituent elements, and the balance is Al.

(2) The above-mentioned materials are smelted at a high temperature in a melting furnace at a temperature of 740°C until they are melted, and the alloy melt is poured into a cylindrical stainless steel mold, and then water-cooled to form an ingot;

(3) Perform uniform solution heat treatment on the ingot, uniform solution temperature/time: 500°C/20h.

(4) Aging temperature/time: 130°C/4.0h+180°C/1.0h.

The tensile strength, yield strength and elongation of the above-mentioned high-strength and high-toughness cast Al-Cu-Zn-Mn-Mg-Ti-Dy aluminum alloy that can be strengthened by heat treatment are as follows:

Tensile strength (MPa) Yield strength (MPa) Elongation (%) Example 1 482.4 383.0 7.5 Example 2 494.7 387.3 7.8 Example 3 518.9 415.4 8.8 Example 4 531.6 423.3 9.5 Example 5 540.1 429.5 9.8 Example 6 548.7 438.1 10.1 Example 7 367.4 301.2 6.2 Example 8 380.5 329.3 5.6 Example 9 374.8 308.7 6.0 Example 10 375.5 306.5 6.3 Example 11 360.1 299.0 5.8

It can be known from the above table that the tensile strength of the semi-solid cast aluminum alloy prepared by the composition formula and preparation method of the present invention can reach 480-550MPa, the yield strength can reach 380-440MPa, and the elongation can reach 7.5-10%. Industrial fields that require high strength and shape.

The above embodiments are only preferred cases for introducing the present invention. For those skilled in the art, any obvious changes and improvements made within the scope of not departing from the spirit of the present invention should be regarded as a part of the present invention.

Claims (4)

1. a kind of heat-treatable strengthened high strength high toughness casting aluminum alloy material, which is characterized in that the aluminum alloy materials by with The group of lower weight percent is grouped as：

Preparation method includes the following steps：

(1) dispensing is carried out in the ratio of above-mentioned each component；

(2) alloy melt, is then cast in mold by the material melting in smelting furnace for preparing step (1), stirs, cooling Obtain ingot casting；

(3) uniform solution heat treatment is carried out to ingot casting；

(4) three-step aging temperature/time：160 DEG C/2.5~4h+180 DEG C/5~8.0h+210 DEG C/1.5~3h.

2. a kind of preparation method of heat-treatable strengthened high strength high toughness casting aluminum alloy material, includes the following steps：

(1) ratio of heat-treatable strengthened high strength high toughness casting aluminum alloy material each component as described in claim 1 carries out Dispensing；

(2) alloy melt, is then cast in mold by the material melting in smelting furnace for preparing step (1), stirs, cooling Obtain ingot casting；

(3) uniform solution heat treatment is carried out to ingot casting；

(4) three-step aging temperature/time：160 DEG C/2.5~4h+180 DEG C/5~8.0h+210 DEG C/1.5~3h.

3. preparation method according to claim 2, which is characterized in that the temperature of step (2) melting is 740 DEG C~780 DEG C.

4. preparation method according to claim 2, which is characterized in that uniformly solid solubility temperature/time is step (3)：500℃ ~530 DEG C/20h~30h.