JP2001181771A - High strength and heat resistant aluminum alloy material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a high strength and heat resistant Al alloy material capable of securing high proof stress when used at high temperature even in the case the hardening rate is made slow in hardening treatment after solution treatment. SOLUTION: This high strength and heat resistant Al alloy material has a composition containing 5.3 to 7.0% Cu, 0.2 to 0.4% Mg and 0.05 to 0.7% Ag, and the balance Al with inevitable impurities and is used after artificial aging treatment in succession to hardening treatment in which the average cooling rate in the range from 400 to 290 deg.C is 10,000 deg.C/min or less. The contents of Zr, Cr and Mn are respectively controlled to <=0.12% Zr, <=0.01% Cr and <=0.4% Mn, and its proof stress after use at 120 deg.C for 100 hr is 350 Mpa or more.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a heat-resistant aluminum alloy material (hereinafter, aluminum is simply referred to as Al) which can increase the proof stress after artificial aging even if the quenching speed after solution treatment becomes slow (small). ).

[0002]

2. Description of the Related Art Aluminum alloy materials used for aerospace equipment such as rockets and aircraft, transportation equipment such as railway vehicles, automobiles, ships, etc., or mechanical parts such as engine parts and compressors. As an Al alloy material which is used at a high temperature exceeding ℃, an Al alloy having excellent high temperature characteristics is used. And, this high temperature property is basically
The creep resistance characteristics and high temperature proof stress of alloy materials under high temperature use.

Conventionally, heat-resistant Al alloy materials having excellent high-temperature characteristics include AA standard or JIS standard 2000 series (hereinafter simply referred to as 2000 type).
Al alloys are used. Of these, in particular, heat-resistant Al such as tanks for space equipment such as rockets, airframes such as aircraft, and wing structures, and turbines, rotors, and liners.
The alloys include Al-Cu-Mn-Zr-V-Ti based 2219Al alloy and Al-C
The u-Mg-Fe-Ni-Si-Ti system 2618Al alloy is mainly used. Among them, the 2219Al alloy has excellent weldability. However, at a high temperature exceeding 120 ° C., the strength of these 2000 series Al alloys decreases significantly when used for a long time. Therefore, when the use condition exceeds 120 ° C., it is a fact that the use time is restricted to a short time or the use environment is kept at a low temperature by adding a cooling device.

[0004] Therefore, in order to improve the creep characteristics and high-temperature proof stress in a high-temperature use environment exceeding 120 ° C, in recent years, a 2519Al alloy (Al-
6.1Cu-0.3Mn-0.15Zr-0.1V) has been developed. A 2519 (Ag) Al alloy in which Ag is added to this 2519Al alloy has also been developed. Also, Al alloys related to these 2519Al alloys and 2519 (Ag) Al alloys are disclosed in JP-A-62-112748 and USP 4610733.
No., 5376192, 5512112, 5593516, 5800927
Nos. 5,665,306, 5,565,063, and 5,630,889.

[0005] The high-temperature characteristics of the 2519Al alloy and the 2519 (Ag) Al alloy, including these related alloys, are described in Metal Sien.
ce, 12 (1978), p. 478, JATayler et al. "or" Metall T
rans, 19A (1988), p. 1027, J. Pollmear et al., in a 2519 Al alloy, the θ 'phase is present on the (100) plane, and 2519 (Ag)
This is because, in the Al alloy, the Ω phase, which is a hexagonal disk-shaped precipitate having a crystal habit plane on the (111) plane, is precipitated.

[0006] On the other hand, the present inventors have proposed the Japan Institute of Light Metals.
Outline of the 93rd Fall Meeting (issued October 20, 1997, 233-2
34 page) and Japanese Patent Application No. 10-108153, have proposed a heat-resistant Al alloy material that can guarantee high high-temperature characteristics with good reproducibility. This content includes Cu: 1.5-7.0%, Mg: 0.01-2.0%, and, optionally, a heat-resistant Al alloy containing Ag: 0.05-0.7%, for the θ ′ phase and / or the Ω phase, θ ′ The average phase size is 120 nm or less and the average spacing between the θ 'phase precipitates is 100 nm or less, the average size of the Ω phase is 100 nm or less, and the average spacing between the Ω phase precipitates is 150 nm or less. It is to be.

Further, the present inventors have disclosed in Japanese Patent Application No. 10-285540 that, similarly to the present invention, a heat-resistant Al alloy forged material for high-speed moving parts has not only high temperature characteristics but also high-speed moving parts. In order to guarantee the machinability, it was proposed that the crystal grain size of the forged Al alloy be equal to or less than 500 μm.

[0008]

However, even if a heat-resistant Al alloy excellent in high-temperature properties is designed by these conventional techniques, the heat-treated Al alloy wrought material actually manufactured is subjected to a solution treatment and a quenching treatment. Even if the high temperature artificial aging treatment is performed, the proof stress is not improved, and the proof stress after the artificial aging treatment required for this kind of heat-resistant Al alloy is reduced, and the proof stress at the time of high temperature use may be reduced. This is the same in the case of Japanese Patent Application Nos. 10-108153 and 10-285540 of the present inventors.

The present inventors have found that the reason is the effect of the quenching speed after the solution treatment. That is, depending on the capacity of the solution treatment and the quenching treatment,
Depending on the thickness of the quenched heat-resistant Al alloy wrought material (in the case of thickness), in order to further suppress the occurrence of residual stress due to quenching, inevitably the Al alloy wrought material after the solution treatment is necessarily The quenching speed (cooling speed) may be slow.

[0010] According to the findings of the present inventors, particularly when quenching treatment is performed after solution treatment,
When the quenching rate (cooling rate) becomes slower (smaller) such that the average quenching rate between 0 ° C and 290 ° C is 30000 ° C / min or less, the yield strength after the artificial aging treatment is low. At the same time, there is a case where the proof stress at the time of using at high temperature becomes low.

The present invention has been made in view of such circumstances, and an object of the present invention is to provide a quenching treatment after a solution treatment, in which even if the quenching speed is reduced, the high yield strength at the time of high temperature use is reduced. An object is to provide a high-strength heat-resistant Al alloy material that can be secured.

[0012]

In order to achieve this object, the gist of the heat-resistant Al alloy material of the present invention is as follows: Cu: 5.3 to 7.0%, Mg:
0.2-0.4%, Ag: 0.05-0.7%, the balance consisting of aluminum and unavoidable impurities, 400% after solution treatment
An aluminum alloy material that is used after being quenched at an average cooling rate between 30,000 ° C and 290 ° C of 30,000 ° C / min or less, and then subjected to artificial aging treatment.
r, Cr, Mn, Zr: 0.09% or less, Cr: 0.05% or less, Mn: 0.6%
Each is regulated below, and the proof stress after being used at a temperature of 120 ° C for 100 hours shall be 350MPa or more.

According to a preferred embodiment of the present invention, the artificial aging treatment after the quenching treatment ensures the proof stress of 350 MPa or more after being used for 100 hours at a temperature of 120 ° C. It is assumed that the Al alloy material does not substantially contain Zr and Cr.

In another preferred embodiment of the present invention, the crystal grain size is reduced to 500 μm or less in order to more reliably ensure the machinability and high-temperature characteristics of the heat-resistant Al alloy material. For this purpose, the Al alloy material further contains V: 0.05 to 0.15%.

In another preferred embodiment of the present invention, the means for spreading the heat-resistant Al alloy material of the present invention is a forging method capable of processing a complicated shape for the heat-resistant material. The heat-resistant Al alloy forged material also has a feature that the quenching speed after the solution treatment is likely to be low, and is most suitable for application of the present invention.

We have identified 2519, including the related alloys.
In the case of Al alloy and 2519 (Ag) Al alloy, the reason why the proof stress does not improve even if high-temperature artificial aging treatment is performed when the cooling rate is reduced in the quenching treatment after the solution treatment.

As a result, a transition element such as Cr, Zr, or Mn added to this kind of heat-resistant Al alloy to improve the room-temperature strength and high-temperature strength by forming a microstructure into a fiber structure is subjected to the high-temperature artificial aging treatment. It has been found that it works on the phenomenon that the proof stress at the time does not improve. In other words, these transition elements precipitate Al-Cr-based, Al-Zr-based, and Al-Mn-based dispersed particles that are thermally stable compounds in the Al matrix during the homogenization heat treatment. These dispersed particles have an effect of hindering the movement of the grain boundary after recrystallization, thereby preventing coarsening of the crystal grains, making the crystal grains fine, and securing the heat resistance of the Al alloy. . Therefore, including the related alloys
In the 2519Al alloy and 2519 (Ag) Al alloy, Cr, Zr, Mn
Etc. are necessarily contained. Among them, particularly Zr is generally regarded as an essential additive element.

However, in the quenching treatment after the solution treatment, the average cooling rate between 400 ° C. and 290 ° C. is 30,000 ° C. /
When the temperature is reduced to less than 1 minute, a stable phase such as AlCu ₂ is coarsely precipitated around the Al-Cr-based, Al-Zr-based, or Al-Mn-based dispersed particles during the quenching process. That is, in particular, Al
-Cr-based, Al-Zr-based, and Al-Mn-based dispersed particles have the negative effect of easily causing the stable phase to precipitate coarsely in the surroundings during the cooling process.

This phenomenon means that Cu necessary for forming the θ ′ phase and the Ω phase has already been consumed by the stable phase precipitated during the quenching process. As a result, during the next high-temperature artificial aging treatment, the θ 'phase and Ω phase, which should be precipitated finely and at high density, precipitate on the (100) and (111) planes of the Al alloy after the artificial aging treatment. Without
Alternatively, even if it is deposited, its absolute amount is insufficient, so that a sufficiently high strength as a heat-resistant Al alloy material cannot be obtained. Therefore, in such an Al alloy material, even if high-temperature artificial aging treatment is performed, the original artificial aging effect cannot be exhibited.

Moreover, the negative effect of the coarse precipitation of the stable phase during the quenching process is generally indispensable and generally used.
The present inventors have also found that Zr and Cr which is less commonly used than Zr are significantly larger than other V and Mn. In other words, Zr, Cr, or Mn is this kind of heat-resistant in the sense of causing the stable phase to coarsely precipitate during the quenching process.
It has the effect of increasing the quenching sensitivity of the Al alloy.

Therefore, in the present invention, the heat-resistant Al alloy
In particular, by regulating the content of Zr, Cr or Mn, which are widely used, and reducing the quenching sensitivity of this kind of heat-resistant Al alloy, the average cooling rate between 400 ° C and 290 ° C after solution treatment is 30,000. In the case of artificial aging after quenching at ℃ / min or less, the proof stress after use for 100 hours at a temperature of 120 ℃ after artificial aging shall be 350 MPa or more.

[0022]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The significance of each requirement of the present invention will be described below.

First, the chemical composition of the Al alloy of the present invention will be described. The chemical composition of the Al alloy of the present invention is basically an Al alloy such as 2519 or 2618 and 2519.
The composition standard of the 2519 (Ag) -based Al alloy obtained by adding Ag to the alloy is good, but it can be appropriately selected from the component composition ranges described below according to more specific applications and required characteristics.

(Cu: 5.3 to 7.0%) Cu is a basic component of the Al alloy of the present invention, and is mainly required in the use of the Al alloy of the present invention by the action of both solid solution strengthening and precipitation strengthening.
It is essential to ensure creep characteristics at normal and high temperatures and high temperature proof stress. More specifically, as described above, during the artificial aging treatment at a high temperature, Cu precipitates a θ ′ phase and an Ω phase finely and densely on the (100) plane and the (111) plane of the Al alloy,
Improves the strength of Al alloy material after artificial aging treatment. This effect is exhibited at 5.3% or more. When the Cu content is less than 5.3%, the above-mentioned effect is small, and the creep characteristics and the high-temperature proof stress at room temperature and high temperature of the Al alloy cannot be obtained. On the other hand, if the Cu content exceeds 7.0%, the strength becomes too high, and workability such as forgeability, rollability, and extrudability deteriorates. Therefore, Cu
Is in the range of 5.3 to 7.0%.

(Mg: 0.2-0.4%) Like Cu, Mg is also used to secure sufficient creep characteristics and high-temperature proof stress of Al alloys at room temperature and high temperature mainly by the actions of solid solution strengthening and precipitation strengthening. Required for More specifically, like Cu, Mg precipitates the θ ′ phase and Ω phase finely and densely on the (100) and (111) planes of the Al alloy during high-temperature artificial aging treatment, Improves the strength of Al alloy material after artificial aging treatment. This effect is exhibited at 0.2% or more, and this effect is not exhibited at a Mg content of less than 0.21%, and the aluminum alloy cannot have sufficient creep characteristics at room temperature and high temperature and high temperature proof stress. on the other hand,
If the Mg content exceeds 0.4%, the strength becomes too high, and cracks called burning occur during solution treatment,
There is a high possibility that workability such as forgeability, rollability, and extrudability will be reduced. Therefore, the content of Mg is set in the range of 0.2 to 0.4%.

(Ag: 0.05-0.7%) In the Al alloy,
A region where a fine and uniform Ω phase is formed and no precipitate phase is present (PFZ: solute-depleted precipitate free zo
ne) is essential to improve the room temperature and high temperature strength of the Al alloy by extremely narrowing the width of the Al alloy. If the Ag content is less than 0.05%, this effect is not obtained. On the other hand, if the Ag content exceeds 0.7%, the effect is saturated. Therefore, the content of Ag is set in the range of 0.05 to 0.7%.

(Zr: 0.09% or less, Cr: 0.05% or less, Mn: 0.6%
Zr, Cr, and Mn are, similarly to V, dispersed in Al-Zr-based, Al-Cr-based, and Al-Mn-based compounds that are thermally stable in the aluminum alloy matrix during the homogenization heat treatment. Precipitate the particles. Then, the dispersed particles have an effect of forming a microstructure of the Al alloy into a fiber structure to improve the room temperature strength and the high temperature strength.

However, as described above, firing after the solution treatment is performed.
Average cooling rate between 400 ° C and 290 ° C
If the temperature slows down to 30000 ° C / min or less, these Zr and C
When r and Mn are contained, it can be used for quenching after solution treatment.
In the quenching process, AlCu _TwoSuch as the stable phase,
Coarse around the dispersed particles of Al-Cr, Al-Zr and Al-Mn
Will precipitate out. As a result, the artificial aging at the next higher temperature
Even after processing, after using for 100 hours at a temperature of 120 ℃
Proof stress of 350MPa or more cannot be obtained. Therefore, the present invention
Then, in order to lower the quenching sensitivity of heat-resistant Al alloy, Zr:
0.09% or less, Cr: 0.05% or less, Mn: 0.6% or less, preferably
Regulates, in particular, to be substantially free of Zr and Cr
This is the biggest feature.

Next, the allowable amounts of other elements, which are selective additional elements or impurities in the present invention, will be described below.

(V: 0.05-0.15%) V, like Zr, Cr and Mn, precipitates Al-V dispersed particles which are thermally stable compounds in the Al alloy matrix during the homogenization heat treatment. In addition, since the dispersed particles have an effect of hindering the movement of the grain boundary after recrystallization, there is an effect of preventing the crystal grains from becoming coarse. As a result, there is an effect that the microstructure of the Al alloy is converted into a fiber structure to improve the room temperature strength and the high temperature strength. The effect of coarsely depositing the stable phase is relatively small as compared with Zr, Cr and Mn. Therefore, V is selectively contained in order to improve the room temperature strength and the high temperature strength. If V: less than 0.05%, these effects cannot be obtained. On the other hand, if V: more than 0.15%, coarse insoluble intermetallic compounds are easily formed during melting and casting, which causes molding failure and destruction. Therefore, when it is contained, the V content is in the range of 0.05 to 0.15%.

(One or two types of Fe: 1.5% or less, Ni: 2.4% or less) Since Fe and Ni both have the effect of improving the high-temperature characteristics of the Al alloy, Fe: 1.5% or less, Ni: 2.4% or less. Permitted up to and including%. Among these, if Fe is contained in excess of 1.5%, an insoluble intermetallic compound is generated, which is likely to cause molding failure and destruction. For this reason, it is basically an impurity, but on the other hand, hardly forms a solid solution in Al, forms a crystallized substance in the matrix by reaction with Al during solidification, and particularly when contained simultaneously with Ni, There is also an effect of forming Al ₉ (Fe—Ni) to improve high-temperature characteristics. Therefore, Fe is allowed up to 1.5% or less, including mixing from scrap.

Ni easily forms coarse NiAl ₃ and inhibits formability. On the other hand, Ni, like Fe, hardly forms a solid solution in Al, and forms a hard crystallized substance (Ni Al ₃ ) in the matrix by reaction with Al during solidification. In particular, when it is contained simultaneously with Fe, it has an effect of forming Al ₉ (Fe-Ni) and improving high-temperature characteristics. Therefore, including contamination from scrap,
Ni: Permitted up to 2.4% or less.

Also, elements other than those described above are permitted to be contained within a range that does not impair the high-temperature characteristics and other characteristics of the Al alloy material according to the present invention. For example, Si combines with Mg to form Mg ₂ Si and Al—Fe—Si crystallized substances in an aluminum matrix. For this reason, during the high temperature artificial aging treatment, θ ′
Mg required to precipitate the phase and the Ω phase and improve the strength of the Al alloy material after the artificial aging treatment is consumed,
The strength of the Al alloy material after the artificial aging treatment decreases. Since the content of Mg is originally smaller than that of Cu, the influence of Si is large. Further, by the solution treatment, most of the crystallized solids form a solid solution, but if excessive Mg ₂ Si is formed, it remains even in the solution treatment and becomes a starting point of fracture, so that the formability is reduced. . Therefore, the content of Si is preferably set to 0.3% or less.

In addition, Ti and B refine the crystal grains, but when added excessively, form coarse intermetallic compounds and serve as a starting point of breakage during the forming process, thus deteriorating the formability.
Therefore, the contents of Ti and B are allowed to be 0.20% or less and 0.005% or less, respectively. In addition, other impurity elements are allowed up to the upper limit values in the AA standard to the JIS standard.

(Preferred structure of Al alloy material)
A preferred structure of the alloy material will be described. The preferred structure of the Al alloy material of the present invention described below, which guarantees high high-temperature characteristics with good reproducibility and also guarantees machinability, is described in Japanese Patent Application No. 10-108153 of the present inventors. And Japanese Patent Application 10-2
It is basically the same as the organizational rules for 85540.

(Grain structure) Among these, first, the preferable grain structure of the Al alloy material of the present invention is to further improve the machinability when cutting the wrought aluminum alloy material for high-speed moving parts, 1000hr creep rupture strength of 250N / m for moving parts
m ² or more and a high temperature proof stress of 280 N / mm ² or more, the microstructure after the solution treatment basically has a crystal grain size of 50 or more.
It is preferable to use equiaxed recrystallized grains having a substantially constant size of 0 μm or less. However, since the 1000 hr creep rupture strength and the high temperature proof strength differ depending on the measurement conditions, the measurement conditions of the 1000 hr creep rupture strength are as follows: stress load direction: L direction, temperature 150
° C., the measurement conditions of the high-temperature proof stress, holding conditions: 120 ~ 18
100 hours at 0 ° C, tensile direction: L direction, tensile temperature: 120 to 180
° C, tensile strain rate: 8 × 10 ^-5 S ^-1 .

When a group of fine recrystallized grains (or subcrystal grains) is present in an equiaxed recrystallized grain structure having a substantially constant size of the Al alloy material, high-temperature properties such as creep properties are degraded. Further, as the recrystallized grain size is larger, the step at the crystal grain interface becomes larger and the machinability is reduced. Therefore, the present invention
Al alloy material is 500 μm or less, preferably 10-500 μm
By having fine recrystallized grains (equiaxed recrystallized grains) of substantially constant size in the range of, more preferably in the range of 50 to 300 μm, both high temperature properties such as creep properties and machinability are provided. Is preferred.

More specifically, from the viewpoint of machinability, the recrystallized grain size of equiaxed recrystallized grains is preferably 500 μm or less,
μm or less is more preferred. Also, in terms of high temperature properties such as creep properties, fine recrystallized grains (or sub-crystal grains)
Is preferably 10% or less in terms of area ratio.

Usually, in order to produce an Al alloy material, a bulk (lumped) ingot of the Al alloy is subjected to hot working such as hot forging, hot rolling, and hot extrusion. At this time, if the working degree of the hot working is large, the microstructure of the Al alloy plate after the solution treatment after the hot working becomes a recrystallized grain structure having a substantially constant size.
In contrast, Al alloys such as ordinary hot forged materials, hot-rolled sheet materials having a large sheet thickness, and thick-walled hot-extruded shapes have a low degree of hot working. Although the microstructure of (1) has some equiaxed recrystallized grains of almost constant size of 500 μm or less, it is considered to be aggregates of fine recrystallized grains (or subcrystal grains) with a grain size of 1 μm or less. It is composed of coarse recrystallized grains, and has a mixed grain structure in which an ingot structure remains partially.

In the case of an Al alloy forged material as an example, this mixed grain structure has a grain size, although equiaxed recrystallized grains partially exist.
Fine recrystallized grains (or sub-crystal grains) of 1 μm or less consist of dense and aggregated clusters and coarse recrystallized grains of several mm to several cm, and in some cases, ingot structure remains. It has a grain structure. The mixed grain structures of various sizes do not disappear even by heat treatment after processing and remain in the product Al alloy forging. And the present inventors have found that this mixed grain structure particularly deteriorates the machinability of the product Al alloy forged material. These mixed grain structures also reduce high-temperature characteristics such as creep characteristics.

The preferred structure of equiaxed recrystallized grains in the present invention is a structure composed of equiaxed recrystallized grains having a distribution size of 500 μm or less, preferably 300 μm or less, and having a substantially constant size. And an organization of approximately constant size
As seen in the mixed grain structure, a group of aggregated fine recrystallized grains (or subcrystal grains) having a particle size of 1 μm or less, coarse recrystallized grains of several mm to several cm, or This means that there is no remaining ingot structure.

However, the preferred structure of equiaxed recrystallized grains in the present invention does not necessarily mean the structure in which the equiaxed recrystallized grains of a certain size are only 100%, but the machinability and creep rupture strength. Incorporation of a cast structure or a mixed-grain structure within a range that does not lower the high-temperature characteristics such as the above is allowed. For example,
Fine recrystallized grains (or sub-crystal grains) with a grain size of 1 μm or less
Does not lower the high-temperature properties such as the machinability and creep rupture strength, even if single crystal grains are present individually dispersed. However, when these are grouped or aggregated in a form where they are attached to each other, the machinability and high-temperature characteristics are reduced. Therefore, from this point, in the microstructure after the solution treatment, the area ratio of aggregated fine recrystallized grains of 1 μm or less is preferably 10% or less.

The identification of equiaxed recrystallized grains and the presence or absence of a mixed grain structure in the present invention can be performed by microetching a sample by electrolytic etching or the like, and observing or measuring the sample with an optical microscope of 50 to 400 times. is there.

(Θ ′ phase and Ω phase) Next, in the structure of the present invention, in order to further enhance high temperature properties such as high temperature proof stress and creep rupture strength, the θ ′ phase precipitated on the (100) plane of the Al alloy ,
It is essential to precipitate an Ω phase that precipitates on the (111) plane, as in the case of the heat-resistant Al alloys of Japanese Patent Application Nos. 10-108153 and 10-285540 of the present inventors. However, according to the present invention, when the θ ′ phase and the Ω phase are subjected to artificial aging treatment, the average cooling rate between 400 ° C. and 290 ° C. at the time of quenching before the aging is
Even when the temperature is as low as 30000 ° C./min or less, it is essential to precipitate finely and at a high density. With conventional heat-resistant Al alloys,
When the cooling rate during the preceding quenching is as slow as 30,000 ° C / min or less, the stable phase is coarsely precipitated in advance, and even after the artificial aging treatment, the stable phase is used after being used at a temperature of 120 ° C for 100 hours. No proof stress of 350MPa or more.

Among the precipitates produced by this artificial aging treatment, the Ω phase, in particular, precipitates on the same plane as the slip plane (111).
Compared to the θ 'phase precipitated on the surface, it exhibits an Orowan mechanism, which is an extremely large obstacle to the movement of the transition, and improves high-temperature proof stress and creep characteristics.

According to the findings of the present inventors, the dispersion state of the θ ′ phase and the Ω phase, that is, the size of each of the θ ′ phase and the Ω phase and the average distance between the precipitates are 2519 to 2519. It governs the high temperature properties (heat resistance) of (Ag) Al alloys. And θ '
If the average distance between the precipitates and the size of each phase and Ω phase is too large, these 2519 Al alloy and 2519 (Ag)
The high-temperature properties of Al alloys deteriorate,
This leads to the inability to produce an Al alloy having high high-temperature characteristics with good reproducibility. Therefore, the average size of the θ 'phase is 120 nm.
And the average spacing between the precipitates in the θ ′ phase is 10
Preferably, it is 0 nm or less, the average size of the Ω phase is 100 nm or less, and the average interval between the precipitates of the Ω phase is 150 nm or less.

When the average size of the θ ′ phase exceeds 120 nm and the average interval between the precipitates of the θ ′ phase exceeds 100 nm, the average size of the Ω phase exceeds 100 nm, If the average spacing between precipitates exceeds 150 nm, the effect of improving the high-temperature properties of these θ 'phase and Ω phase (exhibiting the Orowan mechanism, which is an obstacle to the transition, etc.) is extremely reduced, and as a result, High temperature proof stress and creep characteristics of the Al alloy material are reduced, and there is a possibility that excellent high temperature characteristics cannot be guaranteed.

Further, while satisfying the conditions of the size and the spacing, the θ ′ phase is precipitated at a high density or the higher the number of θ ′ phases, the better the high temperature characteristics. More specifically,
It is preferable that the number of θ ′ phases be 5000 or more / mm ³ ,
More preferably, the number of particles / mm ³ or more is present.

The average size of the θ ′ phase and the Ω phase in the Al alloy structure (matrix) of the present invention and the average spacing between the precipitates were determined by observing the aluminum alloy matrix by a transmission electron microscope (TEM). Do it. More specifically, 5000
Visual observation or image analysis using a TEM at 0x is performed to identify the average size of the θ 'phase and the Ω phase, the average spacing between precipitates, and the number of precipitates.

Further, a method for manufacturing an Al alloy material according to the present invention will be described. First, a molten aluminum alloy melt-adjusted within the component range of the present invention is cast by appropriately selecting a normal melting casting method such as a continuous casting rolling method or a semi-continuous casting method (DC casting method).

The cast ingot is formed into a wrought aluminum alloy having a desired shape determined according to the application by a conventional method. More specifically, for forgings, after homogenization heat treatment, hot forging to make Al alloy forgings, or if necessary (with or without intermediate annealing) cold forging, rolling, or drawing. To an Al alloy material. In addition, as a material for forging,
An extruded material or a rolled material may be used. In addition, for the sheet material, the Al alloy ingot is subjected to a homogenizing heat treatment and then hot-rolled into an Al alloy sheet material, or, if necessary (with or without intermediate annealing), cold-rolled into an Al alloy. Plate material. Further, after the homogenizing heat treatment, the profile (including the wire rod) is hot-extruded and, if necessary (with or without intermediate annealing), is cold-drawn to form an Al alloy profile.

The wrought aluminum alloy after the plastic working is subjected to a solution treatment and a quenching treatment, and if necessary, to the cold working, and then to a high temperature artificial aging treatment. In addition, a relatively small forged material that easily generates residual stress due to quenching,
For comparatively thin plates and profiles, in order to remove residual stress generation, cold aging such as cold forging, cold rolling, stretching, and cold drawing are performed, and then artificial aging is performed.
Preferably, a treatment is performed.

In the cold working such as cold rolling or cold forging before the artificial aging treatment, the θ ′ phase and further the Ω phase are precipitated at a high density while satisfying the conditions of the size and the interval. May be important for you. That is, the cold working before the artificial aging treatment promotes the precipitation of the θ ′ phase, and unless the cold working is performed before the artificial aging treatment, the θ ′ phase cannot be precipitated at a high density,
The number of θ ′ phases does not increase, and the preferable condition that the number of the θ ′ phases is 5000 or more / mm ² may not be satisfied.

Further, the microstructure of the Al alloy material after solution treatment is greatly affected by the degree of hot working such as the forging ratio of hot forging, the rolling ratio of hot rolling, or the extrusion ratio of hot extrusion. You. Therefore, in the case of an Al alloy forging, in order to make the microstructure after solution treatment into equiaxed crystal grains, the forging ratio is 1.
It is preferred to be 5 or more. If the forging ratio is less than 1.5, the structure of the forged Al alloy tends to be mixed. Also, the direction of training is not only one direction, at least two different
It is preferable that the training ratio in each direction is 1.5 or more.

As a furnace used for refining (heat treatment) such as solution treatment and quenching treatment of the Al alloy material, a batch furnace, a continuous annealing furnace, a molten salt bath furnace, an oil furnace and the like can be used as appropriate. In addition, the cooling means at the time of quenching is also improved by the present invention, even if the cooling rate is reduced, so that the strength can be improved. Means such as a Yukon well chant, water immersion, water injection, and air injection can be appropriately selected. However, this solution treatment and quenching are prescribed in JIS-W-1103, MIL-H-6088F, etc. in order to re-dissolve the soluble intermetallic compound and suppress re-precipitation during cooling as much as possible. It is preferable to perform the reaction under the specified conditions.

As described above, for the purpose of forcing strain during quenching and increasing the proof stress of the final product after quenching, a cold rolling mill, a stretcher, a cold drawing machine, a cold forging machine and the like are used. Using it, cold working may be performed.
Furthermore, after solution treatment and quenching, if necessary, cold working may be performed, and then artificial aging treatment may be performed to precipitate the Ω phase and the θ ′ phase in the preferred form.

As described above, the artificial aging conditions are JIS-
It is preferable to carry out under the conditions specified in W-1103 and MIL-H-6088F. However, the solution treatment and quenching conditions are such that the average size of the precipitated θ ′ phase is less than 120 nm, the average interval between the precipitates of the θ ′ phase is 100 nm or less, and Ω
This affects the average spacing between the phase precipitates to 150 nm or less. That is, in order to finely precipitate the θ ′ phase and the Ω phase in the Al alloy of the present invention, the cooling rate is set to 20 ° C. in order to prevent the coarse θ ′ phase to the Ω phase from being precipitated during cooling.
/ Min, preferably 100 ° C./sec. In addition, the higher the heating rate, for example, 10 ° C./min or more, prevents coarsening of crystal grains generated during heating up to the solution treatment temperature, high machinability, and furthermore, fracture toughness and fatigue properties. It is also preferable to obtain a fine crystal excellent in crystallinity.

[0058]

Next, embodiments of the present invention will be described. (Example 1) First, an example of a forged material will be described. table 1
Al alloy ingots with the compositions shown in A to D (500 mm φ × 2000 mm
l) After melting the entire surface to 5mm depth, 510 ℃ × 8
hr homogenized heat treatment (air furnace), cut into 300mml length, reheated to 400 ° C, then 150mmt × 150mmW × 26
It was hot forged into 00mml square bars.

The forged material was cut into various sizes so as to change the quenching speed after the solution treatment, and the temperature was raised at a heating rate of 200 ° C./hr in an air furnace to obtain a 530 ° C. × 6 hr solution. After the aging treatment, it was quenched into water at a boiling temperature of 30 ° C., kept for 10 minutes, and then subjected to a high-temperature artificial aging treatment at 175 ° C. for 18 hours to obtain a test material. Only the comparative example of the 2618 Al alloy composition shown in C of Table 1 shows that the homogenizing heat treatment (air furnace) was performed at 500 ° C for 20 hours, the solution treatment was performed at 530 ° C for 6 hours, and the high-temperature artificial aging was performed at 261 ° C.
The test was carried out on an 8Al alloy under standard conditions (195 ° C. × 18 hours). Further, of the invention examples shown in Table 2, No. 5 was subjected to cold forging at a working ratio of 4% in the length direction after the quenching treatment, and then at 175 ° C. × 18 hours.
Was subjected to high temperature artificial aging treatment.

The tensile properties of these test materials were mechanical properties at room temperature (σB, proof stress, elongation), and the high-temperature properties were as follows: when the test materials were exposed to a high temperature of 120 to 180 ° C. × 100 hours. Mechanical properties at temperature (σB, proof stress, elongation),
Further, creep characteristics such as time to break (rupture time) and creep elongation (rupture time and creep elongation after 1000 hours) when a load of 300 MPa was applied in the L direction at 150 ° C. were measured. These test pieces are parallel part 10mmφ × 28mml
And Table 2 shows the measurement results of the tensile properties of these test materials. In Table 2, the creep characteristics of Invention Examples Nos. 3 and 4 and Comparative Example No. 7 were not measured.

Further, regarding the microstructure of the test material,
Observe the microstructure with an optical microscope of 400x magnification and confirm that it is a substantially equiaxed recrystallized grain structure (equiaxed recrystallized grains of almost constant size in the range of 10 to 500 μm), or Fine recrystallized grains (or sub-crystal grains) of 1 μm or less
Was confirmed to be a mixed grain structure composed of an aggregate of the above and coarse crystal grains. In addition, a transmission electron microscope with a magnification of 20,000 times
By (TEM), the (100) incidence of the microstructure of the test material, (11
1) Analyze the TEM image of the incident light and determine the average size (nm) of the θ 'phase precipitated on the (100) plane and the Ω phase precipitated on the (111) plane of the specimen, and the precipitates of each phase. The average interval (nm) between them was measured.

The machinability of the test material was measured by cutting the test material into a cylindrical round bar having a diameter of 50 mmφ and a length of 300 mml using a lathe. Was evaluated by visual observation of the surface of the round bar.

As is clear from Table 2, Zr, Cr and Mn are
r: 0.09% or less, Cr: 0.05% or less, Mn: 0.6% or less The invention examples Nos. 2 to 5 using Al alloys A and B respectively controlled from 400 ° C. to 290 ° C. during quenching after solution treatment. Excellent mechanical properties at room temperature (σB, proof stress, elongation) even at an average cooling rate of up to 30,000 ° C / min.
It can be seen that the high temperature properties are excellent, such as the proof stress after being used for 100 hours is 350 MPa or more. In Table 2, in Reference Example No. 1, when the cooling rate at the time of quenching is 30,000 ° C./min or more, even when using a conventional Al alloy D having a Zr content higher than the upper limit specified in the present invention, It shows that the mechanical properties at room temperature and the high temperature properties are excellent. Therefore, Reference Example No. 1 shows that the problem of reduction in proof stress of the Al alloy material due to Zr or the like is a problem specific to a case where the cooling rate during quenching after solution treatment is slow.

As a result of the observation of the structures of Invention Examples Nos. 2 to 5, the Al alloy structure was all equiaxed and the average crystal grain size was 50 to 50%.
Particle size of a certain size in the range of 500 μmm, and (100)
The average size (nm) and the average spacing (nm) between precipitates of each phase of the θ 'phase precipitated on the plane and the Ω phase precipitated on the (110) plane
And the number of θ 'phases each satisfied the preferred specifications.

Furthermore, the machinability of the test materials of Invention Examples Nos. 2 to 5 was evaluated by visual observation. The machinability was evaluated as having a smooth surface without surface flaws such as peeling or defects. It was also found that the machinability was excellent.

On the other hand, in Comparative Examples Nos. 6 and 7 using 2618 Al alloy C in which Cu was outside the lower limit of the present invention, the average cooling rate from 400 ° C. to 290 ° C. during quenching after solution treatment was used. 30000
℃ / min or less, mechanical properties at room temperature (σB, proof stress,
Elongation) and high temperature properties such as proof stress after use at a temperature of 120 ° C. for 100 hours are also significantly inferior to those of the examples of the present invention.

Further, the comparative example (conventional example) No. 8 using Al alloy D in which Zr was out of the upper limit also showed a 40% quenching after the solution treatment.
Mechanical properties at room temperature (σB, proof stress, elongation) when the average cooling rate between 0 ° C and 290 ° C is below 30,000 ° C / min
Also, the high-temperature characteristics such as proof stress after using at a temperature of 120 ° C. for 100 hours are significantly inferior to those of the examples of the present invention.

[0068]

[Table 1]

[0069]

[Table 2]

(Example 2) Next, after ingoting an Al alloy ingot (50 mmφ × 2000 mml) having a composition of F to M shown in Table 1, the same as in Example 1, except that the diameter was 15 mmt and the diameter was 200 mmφ. Hot forging into a disk shape. The quenching rate of this forged material after solution treatment is
As shown in Table 3, the heating rate was 200
The temperature was raised at 530 ° C / hr, the solution was treated at 530 ° C x 6 hours, quenched from the boiling temperature into hot water at 95 ° C, held for 10 minutes,
The specimen was subjected to a high-temperature artificial aging treatment at 18 ° C for 18 hours.

The properties of these test materials are as follows: mechanical properties at room temperature (σB, proof stress, elongation);
When the test material was exposed to a high temperature of 120 to 180 ° C x 100 hours,
The mechanical properties (σB, proof stress, elongation) at that temperature were measured. These test pieces had a parallel portion of 10 mmφ × 28 mml. Table 3 shows the results.

Further, regarding the microstructure of the test material,
Microstructure observation was performed in the same manner as in Example 1.

Further, the machinability of the test material was evaluated in the same manner as in Example 1.

As is clear from Table 3, Zr, Cr and Mn are
r: 0.09% or less, Cr: 0.05% or less, Mn: 0.6% or less.Inventive Examples Nos. 9 and 10 using Al alloys F and G, respectively, were quenched from 400 ° C to 290 ° C during quenching after solution treatment. Excellent mechanical properties at room temperature (σB, proof stress, elongation) even at an average cooling rate of up to 30,000 ° C / min.
It can be seen that the high temperature properties are excellent, such as the proof stress after being used for 100 hours is 350 MPa or more.

As a result of the observation of the structures of Invention Examples Nos. 9 and 10, the Al alloy structure was all equiaxed and the average crystal grain size was 50 to 50%.
Particle size of a certain size in the range of 500 μmm, and (100)
The average size (nm) and the average spacing (nm) between precipitates of each phase of the θ 'phase precipitated on the plane and the Ω phase precipitated on the (110) plane
And the number of θ 'phases each satisfied the preferred specifications.

Further, the machinability of the test materials of Invention Examples Nos. 9 and 10 was evaluated by visual observation. It was also found that the machinability was excellent.

On the other hand, Cu was out of the lower limit of the present invention, and Zr was in Comparative Example No. 11 using an Al alloy H out of the upper limit of the present invention. Mg was out of the lower limit of the present invention, and Zr was in the upper limit of the present invention. Aluminum alloy
Comparative Example No. 12 using I, Zr was outside the upper limit of the present invention Al
Comparative Example No. 15 using alloy L and Comparative Example No. 16 using Al alloy M in which Cr deviated from the upper limit of the present invention were obtained between 400 ° C. and 290 ° C. during quenching after solution treatment. Average cooling rate of 30
When the temperature is below 000 ° C / min, the mechanical properties at room temperature (σB, proof stress, elongation) and the high temperature properties such as proof stress after use at 120 ° C for 100 hours are significantly inferior to those of the present invention. .

In Comparative Example No. 13 using Al alloy J in which Mg and Zr were outside the upper limits of the present invention, burning (local melting) occurred during the solution treatment, and the refining treatment could not be performed to the end. And the measurement of the mechanical properties itself was impossible. Also,
Also in Comparative Example No. 14 using an Al alloy K in which Cu was out of the upper limit, cracking occurred during hot forging, so that hot forging itself could not be performed, and measurement of mechanical properties itself was impossible. Therefore, these results indicate the critical significance of the definition of the present invention.

[0079]

[Table 3]

[0080]

According to the present invention, in the quenching treatment after the solution treatment, even if the cooling rate is reduced, the temperature is kept at 120 ° C.
It is possible to provide a high-strength heat-resistant Al alloy material capable of ensuring that the proof stress after being used at the above temperature for 100 hours is 350 MPa or more. Therefore, it has an industrial value in that the applications of the heat-resistant Al alloy material can be expanded.

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (reference) C22F 1/00 692 C22F 1/00 692B

Claims (4)

[Claims] [Claim 1] Cu: 5.3-7.0%, Mg: 0.2-0.4%, Ag: 0.05
~ 0.7%, balance aluminum and unavoidable impurities.After solution treatment, after quenching at an average cooling rate between 400 ℃ and 290 ℃ below 30,000 ℃ / min, artificial aging treatment is used Aluminum alloy material, Zr, Cr, Mn in the aluminum alloy, Zr: 0.0
9% or less, Cr: 0.05% or less, Mn: 0.6% or less
A high-strength heat-resistant aluminum alloy material having a proof stress of 350 MPa or more after being used at a temperature of 0 ° C for 100 hours. 2. The high-strength heat-resistant aluminum alloy material according to claim 1, wherein the aluminum alloy material does not substantially contain Zr and Cr. 3. The method according to claim 1, wherein the aluminum alloy material further comprises V: 0.05 to
3. The high-strength heat-resistant aluminum alloy material according to claim 1, containing 0.15%. 4. The high-strength heat-resistant aluminum alloy material according to claim 1, wherein the aluminum alloy material is a forged material.