ALUMINUM ALLOY MATERIAL AND METHOD FOR PRODUCING SAME

An aluminum alloy material having excellent high-temperature creep strength and a method for producing the aluminum alloy material. The aluminum alloy material has an alloy composition that includes 1.5-6.0 mass % of Cu, 1.0-4.0 mass % of Mg, 0.5-2.0 mass % of Fe, 0.5-2.0 mass % of Ni, 0.1-3.0 mass % of Si, 0.05-0.7 mass % of Mo, 0.01-0.3 mass % of Ti, and a remainder of Al and incidental impurities.

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Description
TECHNICAL FIELD

The present invention relates to an aluminum alloy material and a method for producing the same. Hereinafter, aluminum may also be simply referred to as Al.

BACKGROUND ART

Al alloy materials having excellent high-temperature properties are used for Al alloy parts that serve as operating environments at high temperatures higher than 100° C., such as impellers for automotive turbochargers and pump rotors for industrial machinery (for example, turbo-molecular pumps, vacuum pumps, and diffusion pumps). Moreover, with the improvement in the performances of automobiles, industrial machinery, and the like, heat-resistant strength required for heat-resistant Al alloys has also been increased, and excellent high-temperature creep strength has been required.

Hitherto, Al alloys of 2000 series specified in the AA standards or JIS standards (hereinafter, simply referred to as 2000 series) have been used as these so-called heat-resistant Al alloy materials. Al alloys of this type are, for example, Al—Cu (—Mg)-based 2000 series aluminum alloys, such as 2219 and 2618 alloys. However, when these 2000 series Al alloys are used for a long time at a high temperature higher than 120° C., the strength decreases significantly.

Therefore, techniques for improving the heat-resistant strength of aluminum alloys have been studied to date.

For example, PTL 1 describes a technique for improving creep strength by adding Ag to an Al—Cu—Mg-based alloy corresponding to a 2000 series aluminum alloy and further adding Mn and Cr to be dissolved.

PTL 2 describes a technique for achieving excellent creep strength by controlling crystallized matter of an Al—Cu—Mg-based alloy by controlling the cooling rate during casting.

PTL 3 describes a technique for improving creep strength by finely dispersing, on subgrain boundaries, an intermetallic compound crystallized by adding Zr and Ti.

PTL 4 describes a technique for improving high-temperature creep strength by specifying additive elements and coarsening the crystal grains of an Al—Cu-based alloy.

PTL 5 describes a technique for providing an Al alloy having excellent high-temperature properties (heat resistance, high-temperature fatigue strength, creep resistance at high temperatures, and high-temperature proof stress) and discloses an Al alloy containing Si, Cu, Mn, Mg, Ti, and Ag in predetermined amounts, while restricting Zr to less than a predetermined amount, with the balance being Al and incidental impurities.

CITATION LIST Patent Literature

  • PTL 1: Japanese Unexamined Patent Application Publication No. 2013-142168
  • PTL 2: Japanese Unexamined Patent Application Publication No. 2021-134414
  • PTL 3: Japanese Unexamined Patent Application Publication No. 2017-043802
  • PTL 4: Japanese Unexamined Patent Application Publication No. 2020-066785
  • PTL 5: Japanese Unexamined Patent Application Publication No. 2013-014835

SUMMARY OF INVENTION Technical Problem

Many of the existing techniques for improving high-temperature creep strength of a 2000 series aluminum alloy use a noble metal such as Ag, and therefore have a problem in that the alloy cost increases significantly, although the heat-resistant strength increases (PTL 2 and PTL 5).

In the related art in which the amounts of elements, such as Fe and Ni, which form crystallized matter are specified, sufficient creep strength is not obtained (PTL 2). The technique of adding transition metals, such as Zr and Ti, which have high oxidation tendency improves high-temperature strength but has a problem in that the effect is not sufficiently exerted when the production is performed by casting at a low solidification rate for large-size parts (PTL 5).

That is, there is a need for a technique for significantly improving creep strength at high temperatures compared with those of existing aluminum alloys without using an expensive noble metal, such as Ag, as an additive element even in the case where an aluminum alloy is applied to large-size parts.

In view of the above, an object of the present invention is to provide an aluminum alloy material having excellent high-temperature creep strength and a method for producing the aluminum alloy material.

Solution to Problem

As a result of extensive research and development to impart excellent high-temperature creep strength to an aluminum alloy material having, for example, an Al—Cu-Mg composition typified by 2618 alloy, the inventors of the present invention have found that the above problems can be solved by adding Si and Mo and have completed the present invention.

Specifically, the present invention is as follows.

[1]

An aluminum alloy material having an alloy composition containing:

    • Cu: 1.5% to 6.0% by mass,
    • Mg: 1.0% to 4.0% by mass,
    • Fe: 0.5% to 2.0% by mass,
    • Ni: 0.5% to 2.0% by mass,
    • Si: 0.1% to 3.0% by mass,
    • Mo: 0.05% to 0.7% by mass, and
    • Ti: 0.01% to 0.3% by mass,
    • with the balance being Al and incidental impurities.
      [2]

An aluminum alloy material having an alloy composition containing:

    • Cu: 1.9% to 3.0% by mass,
    • Mg: 1.3% to 3.0% by mass,
    • Fe: 0.9% to 1.3% by mass,
    • Ni: 0.9% to 1.3% by mass,
    • Si: 0.25% to 0.8% by mass,
    • Mo: 0.05% to 0.5% by mass, and
    • Ti: 0.04% to 0.09% by mass,
    • with the balance being Al and incidental impurities.
      [3]

The aluminum alloy material according to [1] or [2],

    • wherein contents of the Si and the Mo are
    • Si: 0.1% to 0.6% by mass, and
    • Mo: 0.3% to 0.7% by mass.
      [4]

The aluminum alloy material according to [1] or [2],

    • wherein contents of the Si and the Mo are
    • Si: 0.35% to 0.8% by mass, and
    • Mo: 0.05% to 0.55% by mass.
      [5]

The aluminum alloy material according to [1] or [2],

    • wherein the aluminum alloy material has a minimum creep rate of 8.5×10−10/sec or less at 160° C. and 250 MPa.
      [6]

A method for producing an aluminum alloy material, the method being a method for producing the aluminum alloy material having the alloy composition according to [1] or [2], the method including performing melt-adjustment of a molten metal having the alloy composition, casting, homogenization treatment, hot working, solution treatment, quenching, and aging treatment in this order.

Advantageous Effects of Invention

The present invention can provide an aluminum alloy material having excellent high-temperature creep strength.

In addition, the method for producing an aluminum alloy material according to the present invention enables the production of an aluminum alloy material having excellent high-temperature creep strength.

DESCRIPTION OF EMBODIMENTS

Embodiments for carrying out the aluminum alloy material according to the present invention will be described in detail below. Note that “to” indicating a numerical range is used to mean that the numerical values before and after it are included as the lower limit value and the upper limit value, respectively.

<Aluminum Alloy Material>

Aluminum alloy materials according to the embodiments have predetermined alloy compositions as aluminum alloys and are used to produce aluminum alloy materials (aluminum alloy parts) having excellent high-temperature creep strength.

An aluminum alloy material according to a first embodiment of the present invention has an alloy composition containing:

    • Cu: 1.5% to 6.0% by mass,
    • Mg: 1.0% to 4.0% by mass,
    • Fe: 0.5% to 2.0% by mass,
    • Ni: 0.5% to 2.0% by mass,
    • Si: 0.1% to 3.0% by mass,
    • Mo: 0.05% to 0.7% by mass, and
    • Ti: 0.01% to 0.3% by mass,
    • with the balance being Al and incidental impurities.

An aluminum alloy material according to a second embodiment of the present invention has an alloy composition containing:

    • Cu: 1.9% to 3.0% by mass,
    • Mg: 1.3% to 3.0% by mass,
    • Fe: 0.9% to 1.3% by mass,
    • Ni: 0.9% to 1.3% by mass,
    • Si: 0.25% to 0.8% by mass,
    • Mo: 0.05% to 0.5% by mass, and
    • Ti: 0.04% to 0.09% by mass,
    • with the balance being Al and incidental impurities.

In an aluminum alloy material according to a third embodiment of the present invention, contents of Si and the Mo in the aluminum alloy material according to the first embodiment or the second embodiment are preferably

    • Si: 0.1% to 0.6% by mass, and
    • Mo: 0.3% to 0.7% by mass.

In an aluminum alloy material according to a fourth embodiment of the present invention, contents of Si and the Mo in the aluminum alloy material according to the first embodiment or the second embodiment are preferably

    • Si: 0.35% to 0.8% by mass, and
    • Mo: 0.05% to 0.55% by mass.

The alloy compositions of the aluminum alloy materials according to the embodiments of the present invention may be adjusted to the above ranges by adding Si and Mo to an Al—Cu—Mg composition typified by AA2618 aluminum alloy.

It has been found that a σ phase (Al5Cu6Mg2), which is a new precipitated phase, can be introduced into the aluminum alloy material according to an embodiment of the present invention by incorporating Si and Mo in specific amounts to thereby significantly improve creep strength at high temperatures.

[Alloy Composition]

The foregoing alloy compositions will be described below.

(Cu: 1.5% to 6% by Mass)

Cu is one of elements essential for the aluminum alloy material according to an embodiment of the present invention to exhibit high-temperature creep strength.

Cu forms a fine precipitate composed of an S phase (Al2CuMg) during aging after solution treatment in the production of the aluminum alloy material when added together with Mg and improves high-temperature creep strength as a result of precipitation strengthening of the S phase.

From the viewpoint of providing the above effect, the Cu content is in a range of 1.5% to 6.0% by mass. If the Cu content is less than 1.5% by mass, the effect of improving high-temperature creep strength is not sufficiently provided. If the Cu content exceeds 6.0% by mass, Al—Cu-based coarse crystallized matter is formed at the casting stage, and the solution treatment takes a long time. The lower limit value of the Cu content is preferably 1.9% by mass or more, more preferably 2.2% by mass or more. The upper limit value of the Cu content is preferably 4.5% by mass or less, more preferably 3.0% by mass less.

(Mg: 1.0% to 4.0% by Mass)

Mg is one of elements essential for the aluminum alloy material according to an embodiment of the present invention to exhibit high-temperature creep strength.

Mg forms a fine precipitate composed of an S phase (Al2CuMg) during aging after solution treatment in the production of the aluminum alloy material when added together with Cu and improves high-temperature creep strength.

From the viewpoint of providing the above effect, the Mg content is in a range of 1.0% to 4.0% by mass. If the Mg content is less than 1.0% by mass, the effect of improving high-temperature creep strength is not sufficiently provided. If the Mg content exceeds 4.0% by mass, the amount of coarse Mg2Si increases, and toughness deteriorates. The lower limit value of the Mg content is preferably 1.2% by mass or more, more preferably 1.3% by mass or more. The upper limit value of the Mg content is preferably 3.5% by mass or less, more preferably 3.0% by mass less. (Fe: 0.5% to 2.0% by mass)

Fe forms an Al—Fe—Ni-based compound, such as Al9FeNi, together with Ni and has a function of suppressing excessive coarsening of the crystal grain size and a function of suppressing deformation near crystal grain boundaries to slightly increase the high-temperature creep strength.

From the viewpoint of providing the above effect, the Fe content is in a range of 0.5% to 2.0% by mass. If the Fe content is less than 0.5% by mass, the effect of suppressing coarsening of the crystal grain size cannot be sufficiently provided. If the Fe content exceeds 2.0% by mass, the amount of crystallized matter excessively increases, and properties other than strength, such as ductility and toughness, are impaired. The lower limit value of the Fe content is preferably 0.7% by mass or more, more preferably 0.9% by mass or more. The upper limit value of the Fe content is preferably 1.6% by mass or less, more preferably 1.3% by mass less.

(Ni: 0.5% to 2.0% by Mass)

Ni forms an Al—Fe—Ni-based compound, such as Al9FeNi, together with Fe and has a function of suppressing excessive coarsening of the crystal grain size and a function of suppressing deformation near crystal grain boundaries to slightly increase the high-temperature creep strength.

The Ni content is in a range of 0.5% to 2.0% by mass. If the Ni content is less than 0.5% by mass, the above effect cannot be sufficiently provided. If the Ni content exceeds 2.0% by mass, the amount of crystallized matter excessively increases, and properties other than strength, such as ductility and toughness, are impaired. The lower limit value of the Ni content is preferably 0.7% by mass or more, more preferably 0.9% by mass or more. The upper limit value of the Ni content is preferably 1.6% by mass or less, more preferably 1.3% by mass less.

(Si: 0.1% to 3.0% by Mass)

Si is one of important elements essential for further improving high-temperature creep strength of the aluminum alloy material according to an embodiment of the present invention compared with high-temperature creep strength of existing Al—Cu—Mg-based aluminum alloys.

Si has a function of promoting the nucleation of the o phase (Al5Cu6Mg2) by forming a cluster at the early stage of aging and attracting Cu with compressive stress formed around the cluster as a driving force.

The inventors of the present invention have conducted studies and found the following: Since the aluminum alloy material according to an embodiment of the present invention contains Si in a predetermined amount, the function of improving the high-temperature creep strength can be provided by the effect of Si alone; however, when the aluminum alloy material contains both Si and Mo in predetermined amounts, the amount of σ phase formed is increased, and the high-temperature creep strength can be further improved.

The Si content is in a range of 0.1% to 3.0% by mass. If the Si content is less than 0.1% by mass, the σ phase is not sufficiently stabilized, and the effect of precipitation of the o phase is not sufficiently provided. If the Si content exceeds 3.0% by mass, a Si phase having an extremely brittle diamond structure is formed, resulting in a problem of deterioration of ductility and toughness. The lower limit value of the Si content is preferably 0.25% by mass or more, 0.3% by mass or more, 0.35% by mass or more, or 0.4% by mass or more. The upper limit value of the Si content is preferably 1.5% by mass or less, more preferably 0.8% by mass or less, still more preferably 0.75% by mass or less, still further more preferably 0.6% by mass or less.

(Mo: 0.05% to 0.7% by Mass)

Mo is an important element essential for further improving high-temperature creep strength of the aluminum alloy material according to an embodiment of the present invention compared with high-temperature creep strength of existing Al—Cu—Mg-based aluminum alloys.

Mo is an element having an extremely slow diffusion coefficient and is an element that has high affinity for (that easily forms a compound or a cluster with) Si. Thus, Mo, which is stably in a dissolved state, promotes the formation of Si clusters to increase the amount of σ phase formed, thereby maximizing the precipitation strengthening action of the σ phase obtained by the addition of Si and significantly improving high-temperature creep strength.

The Mo content is 0.05% to 0.7% by mass. If the Mo content is less than 0.05% by mass, the σ phase is not sufficiently formed, and the effect of precipitation of the σ phase is not sufficiently provided. If the Mo content exceeds 0.7% by mass, the amount of coarse Al—Mo—Mg-based crystallized matter is increased, resulting in a problem of a decrease in the high-temperature creep strength. The lower limit value of the Mo content is preferably 0.05% by mass or more, more preferably 0.1% by mass or more, still more preferably 0.15% by mass or more, still further more preferably 0.2% by mass or more. The lower limit value of the Mo content may be 0.3% by mass or more. The upper limit value of the Mo content is preferably 0.6% by mass or less, 0.55% by mass or less, 0.5% by mass or less, or 0.4% by mass or less.

The aluminum alloy material according to another embodiment of the present invention preferably has a Si content of 0.1% to 0.6% by mass and a Mo content of 0.3% to 0.7% by mass.

The aluminum alloy material according to still another embodiment of the present invention preferably has a Si content of 0.35% to 0.8% by mass and a Mo content of 0.05% to 0.55% by mass.

When the Si content and the Mo content are within the above ranges, the effect of improving the high-temperature creep strength is more likely to be provided.

(Ti: 0.01% to 0.3% by Mass)

Ti is an element that is effective to refine the crystal grains.

The Ti content is in a range of 0.01% to 0.3% by mass. If the Ti content is less than 0.01% by mass, the effect of stabilizing a fine crystal grain structure is not sufficiently provided. If the Ti content exceeds 0.1% by mass, for example, a coarse Ti-based compound is formed, resulting in a decrease in the high-temperature creep strength. The lower limit value of the Ti content is preferably 0.02% by mass or more, more preferably 0.04% by mass or more. The upper limit value of the Ti content is preferably 0.15% by mass or less, more preferably 0.09% by mass or less.

(Balance: Al and Incidental Impurities)

The balance of the aluminum alloy material according to an embodiment of the present invention is Al and incidental impurities. The incidental impurities are impurities that are, in the actual operation, derived from, for example, raw materials used or incidentally mixed during melting of the raw materials. Examples of the incidental impurities include Zn, Mn, Cr, Zr, and V.

One or two or more of these may be contained as long as the advantages of the present invention are not impaired. The contents of Zn, Mn, Cr, Zr, and V mentioned as the above examples are each preferably 0.15% by mass or less. Even if the aluminum alloy material according to an embodiment of the present invention contains each of Zn, Mn, Cr, Zr, and V in an amount of 0.15% by mass or less, the advantages of the present invention are not affected.

[Minimum Creep Rate]

The aluminum alloy material according to an embodiment of the present invention preferably has a minimum creep rate of 8.5×10−10/sec or less at 160° C. and 250 MPa.

The minimum creep rate can be determined by a uniaxial tensile high-temperature creep rate test in accordance with JIS Z 2271:2010. For the high-temperature creep rate test, test conditions are set such that the temperature is 160° C. and the stress is 250 MPa, and the test is performed by holding the test temperature for 1.5 hours or more and subsequently applying the test stress.

A creep rate corresponding to the “slope” of the relationship between the test time and the creep elongation obtained in the high-temperature creep rate test is calculated, and the smallest creep rate can be determined as the minimum creep rate. A smaller value of the minimum creep rate means better high-temperature creep strength.

As described above, the aluminum alloy material according to an embodiment of the present invention has a predetermined alloy composition, and therefore excellent high-temperature creep strength can be provided.

<Method for Producing Aluminum Alloy Material>

Next, one embodiment of a method for producing an aluminum alloy material according to an embodiment of the present invention will be described. In the following description related to the production method, a detailed explanation of the matters that have already been described is omitted.

The method for producing an aluminum alloy material according to the present embodiment is a method for producing the aluminum alloy material having the foregoing alloy composition and includes performing melt-adjustment of a molten metal having the alloy composition, casting, homogenization treatment, hot working, solution treatment, quenching, and aging treatment in this order.

Specifically, the method for producing an aluminum alloy material according to the embodiment is a method for producing an aluminum alloy material having an alloy composition containing:

    • Cu: 1.5% to 6.0% by mass,
    • Mg: 1.0% to 4.0% by mass,
    • Fe: 0.5% to 2.0% by mass,
    • Ni: 0.5% to 2.0% by mass,
    • Si: 0.1% to 3.0% by mass,
    • Mo: 0.05% to 0.7% by mass, and
    • Ti: 0.01% to 0.3% by mass,
    • with the balance being Al and incidental impurities, the method including:

performing melt-adjustment of a molten metal having the foregoing alloy composition, casting, homogenization treatment, hot working (plastic working), solution treatment, quenching, and aging treatment in this order.

The method for producing an aluminum alloy material according to the present invention, that is, the melt-adjustment of a molten metal, casting, homogenization treatment, hot working, solution treatment, quenching, and aging treatment can be performed under general conditions for an aluminum alloy material made of, for example, AA2618 aluminum alloy.

In the following, the case where the hot working is forging will be described by way of an example, but the hot working may be any of forging, extrusion, rolling, form rolling, press forming, and the like.

For example, the melt-adjustment of the molten metal can be performed at 700° C. to 900° C.

The homogenization treatment can be performed at 450° C. to 550° C. However, when the Cu concentration is about 2.7% or more, eutectic melting may occur, and therefore, it is desirable to set the temperature of the homogenization treatment to be low in the above range.

The forging can be performed at 200° C. to 500° C. The solution treatment can be performed at 500° C. to 550° C.

The quenching can be performed using water or oil at a temperature of 90° C. to 100° C., but can also be performed with water or typical heat-treatment oil at room temperature (about 25° C.).

The aging treatment can be performed at 170° C. to 220° C.

Specifically, this production method can be performed by T6 treatment or T61 treatment and is preferably performed by T61 treatment. Under the above production conditions, this production method can produce the aluminum alloy material according to the embodiment. Note that this production method is not limited to the general conditions described as examples herein.

The method for producing an aluminum alloy material according to the embodiment is as described above; however, as for conditions that are not explicitly described, publicly known conditions may be adopted in each of the above processes, and the conditions can be appropriately changed as long as the effect obtained by the treatment in each process is achieved.

[Aluminum Alloy Parts]

The aluminum alloy materials according to the embodiments can be subjected to hot working to provide near-net shapes, followed by cutting work to produce rotational parts and direct-acting parts (aluminum alloy parts) such as impellers for engines, compressors, and turbochargers.

As described above, the following matters are disclosed herein.

[1]

An aluminum alloy material having an alloy composition containing:

    • Cu: 1.5% to 6.0% by mass,
    • Mg: 1.0% to 4.0% by mass,
    • Fe: 0.5% to 2.0% by mass,
    • Ni: 0.5% to 2.0% by mass,
    • Si: 0.1% to 3.0% by mass,
    • Mo: 0.05% to 0.7% by mass, and
    • Ti: 0.01% to 0.3% by mass,
    • with the balance being Al and incidental impurities.
      [2]

An aluminum alloy material having an alloy composition containing:

    • Cu: 1.9% to 3.0% by mass,
    • Mg: 1.3% to 3.0% by mass,
    • Fe: 0.9% to 1.3% by mass,
    • Ni: 0.9% to 1.3% by mass,
    • Si: 0.25% to 0.8% by mass,
    • Mo: 0.05% to 0.5% by mass, and
    • Ti: 0.04% to 0.09% by mass,
    • with the balance being Al and incidental impurities.
      [3]

The aluminum alloy material according to [1] or [2],

    • wherein contents of the Si and the Mo are
    • Si: 0.1% to 0.6% by mass, and
    • Mo: 0.3% to 0.7% by mass.
      [4]

The aluminum alloy material according to [1] or [2],

    • wherein contents of the Si and the Mo are
    • Si: 0.35% to 0.8% by mass, and
    • Mo: 0.05% to 0.55% by mass.
      [5]

The aluminum alloy material according to any one of [1] to [4],

    • wherein the aluminum alloy material has a minimum creep rate of 8.5×10−10/sec or less at 160° C. and 250 MPa.
      [6]

A method for producing an aluminum alloy material, the method being a method for producing the aluminum alloy material having the alloy composition according to any one of [1] to [5], the method including performing melt-adjustment of a molten metal having the alloy composition, casting, homogenization treatment, hot working, solution treatment, quenching, and aging treatment in this order.

EXAMPLES

The present invention will be more specifically described below with reference to Examples and Comparative Examples; however, the present invention is not limited to these Examples. The present invention can be implemented in various modifications without departing from the spirit of the present invention, and such modifications are all included in the technical scope of the present invention.

Examples and Comparative Examples

Small-size ingots having the compositions (balance: Al and incidental impurities) shown in Tables 1 and 2 and each having a mass of about 1.6 kg were produced by “ingot casting” in which casting was performed by pouring a molten metal made of an aluminum alloy into a casting mold with dimensions of 170 mm×110 mm×28 mm.

The concentration of each element was analyzed by plasma emission spectrometry.

The ingots were each held at 500° C. for 12 hours as homogenization treatment, then formed into a rectangular material with dimensions of 40 mm×40 mm as they are by hammer forging including reheating once, and subjected to, as T61 treatment, holding at 530° C. for 6 hours followed by immersion water cooling at 90° C., and aging treatment at 200° C. for 22 hours followed by natural cooling to produce aluminum alloy materials of Nos. 1 to 11, which were used as sample materials.

(Measurement of Minimum Creep Rate)

For evaluation of mechanical properties, a uniaxial tensile high-temperature creep rate test was performed in accordance with JIS Z 2271:2010.

The test was performed using a single-type creep testing machine, and the creep elongation during the test was also measured using a dial gauge extensometer in combination.

A test piece has a round-bar shape having a total length of 80 mm and prepared by cutting out from the above rectangular material and has a gauge section with a flange, the gauge section having dimensions of φ6 mm×30 mm in length, and grip sections with a M12 screw shape.

The test conditions were set such that the temperature was 160° C. and the stress was 250 MPa. After the test temperature was held for 1.5 hours or more, the test stress was applied to start the test.

A creep rate corresponding to the “slope” of the relationship between the test time and the creep elongation obtained in the creep rate test was calculated, and the smallest creep rate was determined as the minimum creep rate. A smaller value of the minimum creep rate means better high-temperature creep strength. A minimum creep rate of 8.5×10−10/sec or less was rated pass (o), and a minimum creep rate exceeding that was rated fail (x). Note that this criteria for pass or fail corresponds to a threshold which means that the lifetime is about 1.7 times those of existing materials when used under the same conditions.

The above results are shown in Tables 1 and 2.

TABLE 1 Minimum creep rate Pass Composition (mass %) or No. Si Fe Cu Mn Mg Cr Zn Ti Ni Mo /sec fail Example 1 0.496 1.08 2.50 0.02 1.49 0.02 0.04 0.06 1.10 0.48 5.32 × ∘ 10−10 2 0.510 1.08 2.49 0.02 1.51 0.02 0.03 0.06 1.11 0.47 3.73 × ∘ 10−10 3 0.492 1.07 2.48 0.02 1.48 0.02 0.03 0.06 1.09 0.11 8.32 × ∘ 10−10 4 0.229 1.09 2.49 0.02 1.50 0.02 0.03 0.06 1.11 0.51 7.86 × ∘ 10−10 Comparative 5 0.523 1.09 2.49 0.02 1.51 0.02 0.03 0.06 1.11 — 8.78 × x Example 10−10 6 0.192 1.10 2.51 0.02 1.47 0.02 0.03 0.06 1.11 <0.01 1.55 × x 10−9 7 0.215 1.08 2.48 0.02 1.50 0.02 0.03 0.06 1.10 — 1.16 × x 10−9

As shown in Table 1, the aluminum alloy materials of Nos. 1 to 4 corresponding to Examples of the present invention had excellent high-temperature creep strength. The aluminum alloy materials of Nos. 5 to 7 correspond to Comparative Examples in which the Mo content is outside the range specified in the present invention. It is presumed that, in the aluminum alloy materials of Nos. 5 to 7, the formation of the σ phase was not promoted and precipitation strengthening did not work sufficiently, resulting in high minimum creep rates, that is, poor high-temperature creep strength.

TABLE 2 Minimum creep rate Pass Composition (mass %) or No. Si Fe Cu Mn Mg Cr Zn Ti Ni Mo /sec fail Example 8 0.50 1.06 2.49 0.02 1.49 0.02 0.03 0.06 1.10 0.31 5.64 × ∘ 10−10 9 0.51 1.07 2.51 0.02 1.46 0.02 0.03 0.06 1.09 0.64 7.67 × ∘ 10−10 Comparative 10 0.52 1.06 2.51 0.02 1.46 0.02 0.03 0.06 1.10 0.03 1.26 × x Example 10−9 11 3.65 1.09 2.47 0.02 1.46 0.02 0.03 0.06 1.10 0.31 2.06 × x 10−4

As shown in Table 2, the aluminum alloy materials of Nos. 8 and 9 corresponding to Examples of the present invention had excellent high-temperature creep strength. The aluminum alloy material of No. 10 corresponds to a Comparative Example in which the Mo content is outside the range specified in the present invention. It is presumed that, in the aluminum alloy material of No. 10, the Mo concentration was insufficient and thus the σ phase was not sufficiently precipitated, resulting in a high minimum creep rate, that is, poor high-temperature creep strength. The aluminum alloy material of No. 11 corresponds to a Comparative Example in which the Si content is outside the range specified in the present invention. Presumably, in the aluminum alloy material of No. 11, since the Si concentration was excessive, a fine precipitated structure such as the S phase, which an aluminum alloy material having an Al—Cu—Mg composition originally has, was inhibited, and a basic strengthening mechanism was impaired, resulting in a high minimum creep rate, that is, poor high-temperature creep strength.

It has been demonstrated that since the aluminum alloy materials according to the embodiments of the present invention have predetermined alloy compositions, it is possible to provide aluminum alloy materials having excellent high-temperature creep strength.

Although various embodiments have been described above, it goes without saying that the present invention is not limited to these examples. It will be apparent that those skilled in the art may conceive of various variations and modifications within the scope defined in the claims, and it is understood that such variations and modifications also fall within the technical scope of the present invention. The constituents in the above embodiments may be freely combined without departing from the spirit of the invention.

The present application is based on Japanese Patent Application (No. 2022-027200) filed on Feb. 24, 2022 and Japanese Patent Application (No. 2022-182576) filed on Nov. 15, 2022, the contents of which are incorporated herein by reference.

Claims

1. An aluminum alloy material comprising an alloy composition containing:

Cu: 1.5% to 6.0% by mass,
Mg: 1.0% to 4.0% by mass,
Fe: 0.5% to 2.0% by mass,
Ni: 0.5% to 2.0% by mass,
Si: 0.1% to 3.0% by mass,
Mo: 0.05% to 0.7% by mass,
Ti: 0.01% to 0.3% by mass, and
Al.

2. An aluminum alloy material comprising an alloy composition containing:

Cu: 1.9% to 3.0% by mass,
Mg: 1.3% to 3.0% by mass,
Fe: 0.9% to 1.3% by mass,
Ni: 0.9% to 1.3% by mass,
Si: 0.25% to 0.8% by mass,
Mo: 0.05% to 0.5% by mass,
Ti: 0.04% to 0.09% by mass, and
Al.

3. The aluminum alloy material according to claim 1, wherein contents of the Si and the Mo are

Si: 0.1% to 0.6% by mass, and
Mo: 0.3% to 0.7% by mass.

4. The aluminum alloy material according to claim 1, wherein contents of the Si and the Mo are

Si: 0.35% to 0.8% by mass, and
Mo: 0.05% to 0.55% by mass.

5. The aluminum alloy material according to claim 1, wherein the aluminum alloy material has a minimum creep rate of 8.5×10−10/sec or less at 160° C. and 250 MPa.

6. A method for producing the aluminum alloy material having the alloy composition according to claim 1, the method comprising performing melt-adjustment of a molten metal having the alloy composition, casting, homogenization treatment, hot working, solution treatment, quenching, and aging treatment in this order.

7. The aluminum alloy material according to claim 2, wherein contents of the Si and the Mo are

Si: 0.1% to 0.6% by mass, and
Mo: 0.3% to 0.7% by mass.

8. The aluminum alloy material according to claim 2, wherein contents of the Si and the Mo are

Si: 0.35% to 0.8% by mass, and
Mo: 0.05% to 0.55% by mass.

9. The aluminum alloy material according to claim 2, wherein the aluminum alloy material has a minimum creep rate of 8.5×10−10/sec or less at 160° C. and 250 MPa.

10. A method for producing the aluminum alloy material having the alloy composition according to claim 2, the method comprising performing melt-adjustment of a molten metal having the alloy composition, casting, homogenization treatment, hot working, solution treatment, quenching, and aging treatment in this order.

Patent History
Publication number: 20250101547
Type: Application
Filed: Jan 23, 2023
Publication Date: Mar 27, 2025
Applicant: Kabushiki Kaisha Kobe Seiko Sho (Kobe Steel, Ltd.) (Kobe-shi)
Inventors: Takeo MIYAMURA (Kobe-shi), Toshiyuki TANAKA (Inabe-shi), Naohiro KOISO (Inabe-shi)
Application Number: 18/728,146
Classifications
International Classification: C22C 21/16 (20060101); C22F 1/057 (20060101);