WO2017033663A1

WO2017033663A1 - Aluminum alloy extruded material and method for producing same

Info

Publication number: WO2017033663A1
Application number: PCT/JP2016/072198
Authority: WO
Inventors: 裕子玉田; 八太　秀周; 紘一石田
Original assignee: 株式会社Uacj; 株式会社Ｕａｃｊ押出加工
Priority date: 2015-08-25
Filing date: 2016-07-28
Publication date: 2017-03-02
Also published as: US20180237889A1; JP6348466B2; JP2017043802A; DE112016003841T5; CN107636181B; CN107636181A

Abstract

This aluminum alloy extruded material has a chemical composition that contains, in mass%, 2.5-3.3% of Cu, 1.3-2.5% of Mg, 0.50-1.3% of Ni, 0.50-1.5% of Fe, less than 0.50% of Mn, 0.15-0.40% of Si, 0.06-0.20% of Zr and less than 0.05% of Ti, with the balance made up of Al and unavoidable impurities. In a cross-section of this aluminum alloy extruded material, the circle-equivalent diameters of intermetallic compound particles are 20 μm or less; the density of intermetallic compound particles having circle-equivalent diameters of 0.3-20 μm is 5 × 10³ particles/mm² or more; and the average circle-equivalent diameter of crystal subgrains is 20 μm or less.

Description

Aluminum alloy extruded material and method for producing the same

Cross-reference of related applications

This international application claims priority based on Japanese Patent Application No. 2015-165985 filed with the Japan Patent Office on August 25, 2015, and Japanese Patent Application No. 2015-165985 The entire contents are incorporated by reference into this international application.

The present disclosure relates to an aluminum alloy extruded material and a manufacturing method thereof.

In recent years, from the viewpoint of environmental protection, improvement in fuel consumption of automobile internal combustion engines has been demanded. Aluminum alloy materials applied to automobile internal combustion engine parts (for example, pistons) and supercharger parts (for example, compressor wheels) are used in high temperature areas and high temperature areas to increase the output of internal combustion engines. There is a need for creep resistance that can withstand long-term use.

For example, Patent Document 1 proposes that the electrical conductivity and the average particle diameter of the intermetallic compound be controlled within a predetermined range in order to improve the strength of the aluminum alloy material in a high temperature range (100 to 180 ° C.). Yes. Patent Document 2 proposes that the contents of Fe and Ni satisfy a predetermined relationship in order to improve the strength of an aluminum alloy material in a high temperature range (200 ° C. or higher).

Japanese Patent Laid-Open No. 1-152237 Japanese Unexamined Patent Publication No. 7-242976

However, in Patent Documents 1 and 2 described above, although the strength of the aluminum alloy material in the high temperature range has been studied, the creep resistance in the high temperature range has not been studied at all. That is, conventionally, sufficient investigation has not been made on the creep resistance of aluminum alloy materials at high temperatures.

In one aspect of the present disclosure, an aluminum alloy extruded material excellent in strength and creep resistance at high temperatures and a manufacturing method thereof are desirable.

One aspect of the present disclosure is an aluminum alloy extruded material, and in terms of mass%, Cu: 2.5 to 3.3%, Mg: 1.3 to 2.5%, Ni: 0.50 to 1.3 %, Fe: 0.50 to 1.5%, Mn: Less than 0.50%, Si: 0.15 to 0.40%, Zr: 0.06 to 0.20%, Ti: Less than 0.05% And the balance is a chemical composition consisting of Al and inevitable impurities, and in the cross section, the particle size of the intermetallic compound is 20 μm or less in equivalent circle diameter, and the particle size is 0.3 to 20 μm in equivalent circle diameter. The density of the intermetallic compound is 5 × 10 ³ particles / mm ² or more, and the average grain size of the sub-crystal grains is 20 μm or less in terms of the equivalent circle diameter.

According to this aluminum alloy extruded material, for example, the strength and creep resistance in a high temperature range of 200 ° C. or higher can be improved. Here, regarding the strength, not only the strength in the extrusion direction (hereinafter, appropriately referred to as L direction) but also the strength in the direction orthogonal to the extrusion direction (hereinafter, appropriately referred to as LT direction) can be improved. Further, regarding the creep resistance, the creep resistance in the LT direction can be improved. Thereby, the aluminum alloy extruded material of the present disclosure can be applied to, for example, a part for an internal combustion engine of an automobile used in a high temperature environment, a part for a supercharger, or the like.

Another aspect of the present disclosure is a method for producing the aluminum alloy extruded material, in which an ingot of the aluminum alloy having the chemical composition is homogenized at 400 to 500 ° C., and then the ingot is 0.01 ° C. Is cooled from the homogenization temperature to a temperature of 200 ° C. or less at an average cooling rate of at least / s, and then the ingot is extruded at 310 to 450 ° C., and then the intermediate extruded material obtained by the extrusion process Then, solution treatment and quenching are performed, then, after solution treatment and quenching, the intermediate extrudate is subjected to 2-4% strain correction within 48 hours, and then the intermediate extrudate is subjected to tension correction. Aging treatment at 160-220 ° C.

According to this method for producing an aluminum alloy extruded material, for example, an aluminum alloy extruded material excellent in strength (strength in the L direction and LT direction) and creep resistance (particularly creep resistance in the LT direction) in a high temperature range of 200 ° C. or higher. Can be manufactured. The manufactured aluminum alloy extruded material can be applied to, for example, automobile internal combustion engine parts, turbocharger parts and the like used in a high temperature environment.

Hereinafter, embodiments of the present disclosure will be described. Note that the present disclosure is not limited to the following embodiments, and it is needless to say that the present disclosure can be implemented in various modes without departing from the gist of the present disclosure.

<Chemical composition of extruded aluminum alloy>
Cu: 2.5-3.3%
Cu contributes to improving the strength of the aluminum alloy extruded material at room temperature and high temperature. When the Cu content is less than 2.5%, the effect of improving the strength cannot be obtained sufficiently. When the Cu content exceeds 3.3%, the eutectic melting start temperature is lowered and the solution treatment temperature has to be lowered, so the amount of solid solution in the parent phase is reduced, and the effect of improving the strength. I can't hope.

Mg: 1.3-2.5%
Mg coexists with Cu and contributes to improving the strength of the extruded aluminum alloy at room temperature and high temperature. When the Mg content is less than 1.3%, the effect of improving the strength is small. When the Mg content exceeds 2.5%, the deformation resistance of the processed material is increased in hot working such as extrusion, and the productivity is lowered.

Ni: 0.50 to 1.3%
Ni forms an Fe—Ni compound together with Fe and improves the heat resistance of the extruded aluminum alloy. When the Ni content is less than 0.50%, the effect of improving heat resistance cannot be sufficiently obtained. When the Ni content exceeds 1.3%, Ni-based compounds such as Al-Ni-based and Al-Ni-Cu-based that are dispersed in the parent phase are formed, so the effect of improving heat resistance is reduced. . In addition, the formation of a coarse Fe—Ni-based compound makes it easy for cracks to occur due to hot working such as extrusion, resulting in decreased productivity.

Fe: 0.50 to 1.5%
Fe forms a Fe—Ni compound together with Ni and improves the heat resistance of the aluminum alloy extruded material. When the Fe content is less than 0.50%, the effect of improving heat resistance cannot be sufficiently obtained. When the Fe content exceeds 1.5%, an Fe-based compound such as an Al-Fe-based or Al-Fe-Cu-based material that is dispersed in the parent phase is formed, so that the effect of improving heat resistance is reduced. .

Mn: less than 0.50% Mn precipitates and disperses Al-Mn-Si compounds, suppresses recrystallization that occurs during solution treatment, and forms fine sub-crystal grains. Contributes to improving the strength of extruded aluminum alloys. When the Mg content is 0.50% or more, a huge crystallized product is easily formed during casting, and the strength is lowered.

Si: 0.15-0.40%
Si precipitates a finely dispersed phase of Al-Mn-Si compound together with Mn, enhances the pinning effect of dislocation, and suppresses the coarsening of recrystallized grains during solution treatment. To improve. When the Si content is less than 0.15%, the effect of improving the strength cannot be obtained sufficiently. When the Si content exceeds 0.40%, Mg and Si compounds are formed, and the heat resistance is lowered.

Zr: 0.06 to 0.20%
Zr contributes to refinement of the cast structure. In addition, Zr finely disperses Al ₃ Zr compound together with Al, suppresses recrystallization that occurs during solution treatment, and forms fine sub-crystal grains, thereby contributing to improvement in strength of the aluminum alloy extruded material. . When the Zr content is less than 0.06%, the effect of making the cast structure fine and improving the strength cannot be sufficiently obtained. When the Zr content exceeds 0.20%, a large crystallized product is likely to be formed during casting, so that the effects of refinement of the cast structure and improvement in strength are reduced.

Ti: Less than 0.05% Ti is added in order to stably obtain a fine grain structure, like Zr. The Ti content is less than 0.05%. When the Ti content is 0.05% or more, a huge Zr—Ti-based compound is formed during casting, and the strength decreases.

Other elements:
In addition to the above elements, basically, Al and inevitable impurities may be used. Usually, elements other than the above elements added to the aluminum alloy are allowed as long as they do not significantly affect the characteristics as inevitable impurities.

<Structure of extruded aluminum alloy>
In an aluminum alloy extruded material, in order to suppress the coarsening of the sub-crystal grain size at high temperature and to realize excellent strength and creep resistance, the crystal on the sub-grain boundary is prevented so that dislocation does not move easily at high temperature. There must be a small amount of artifacts. Therefore, in the cross section of the aluminum alloy extruded material, the particle diameter of the intermetallic compound is 20 μm or less (preferably 10 μm or less) in terms of the equivalent circle diameter, and the density of the intermetallic compound having the equivalent particle diameter of 0.3 to 20 μm 5 × 10 ³ pieces / mm ² or more.

In the cross section of the aluminum alloy extruded material, when the particle diameter of the intermetallic compound exceeds 20 μm in the equivalent circle diameter, it becomes a starting point at the time of fracture, and the strength is reduced. In the cross section of the aluminum alloy extruded material, when the density of the intermetallic compound having a grain equivalent diameter of 0.3 to 20 μm is less than 5 × 10 ³ pieces / mm ² , the precipitates on the grain boundaries are sparse. That is, the grain boundary sliding is not suppressed and the heat resistance is lowered.

In order to improve the strength of the aluminum alloy extruded material at a high temperature (particularly the strength in the LT direction), the average grain size of the sub-crystal grains is set to 20 μm or less in terms of the equivalent circle diameter in the cross section of the aluminum alloy extruded material. In the cross section of the aluminum alloy extruded material, when the average grain size of the sub-crystal grains exceeds 20 μm in the equivalent circle diameter, the effect of improving the strength at high temperature (particularly the strength in the LT direction) is reduced.

Here, the cross section of the aluminum alloy extruded material is a cross section in a predetermined direction of the aluminum alloy extruded material. The direction of the cross section is not limited at all, and may be a cross section parallel to the extrusion direction, a cross section perpendicular to the extrusion direction, or the like. The particle size (equivalent circle diameter) of the above-mentioned intermetallic compound, the density of the intermetallic compound having a particle diameter (equivalent circle diameter) of 0.3 to 20 μm, and the average grain size (equivalent circle diameter) of the subcrystalline grains are aluminum. This can be determined by observing an arbitrary region of the extruded alloy material in a predetermined direction, excluding a surface layer portion (for example, a range of 2 to 5 mm in the depth direction from the surface) with an optical microscope or the like.

<Method for producing aluminum alloy extruded material>
In producing the aluminum alloy extruded material, first, an aluminum alloy having the above chemical composition is melted by a conventional method, and the ingot of the ingot aluminum alloy is homogenized at 400 to 500 ° C. When the temperature of the homogenization treatment is less than 400 ° C., the tissue is not sufficiently homogenized. When the temperature of the homogenization treatment exceeds 500 ° C., eutectic melting occurs in the portion where the elements are segregated.

Next, the ingot of the aluminum alloy after the homogenization treatment is cooled from the temperature of the homogenization treatment to a predetermined temperature of 200 ° C. or less at an average cooling rate of 0.01 ° C./s or more. Here, the average cooling rate is (A ° C.−200 ° C.) / B seconds, where the temperature of the homogenization treatment is A ° C. and the time required for cooling the ingot from A ° C. to 200 ° C. is B seconds. expressed. When the average cooling rate is less than 0.01 ° C./s (slower than 0.01 ° C./s), the S phase (Al ₂ CuMg) and / or the Fe—Ni compound grows coarsely during cooling. .

For example, when an extrusion process at 450 ° C. or less is performed in a state where a coarse compound is formed, the dislocation introduced by the extrusion process disappears in the vicinity of the coarse compound, and the subcrystal grain size becomes coarse. In particular, the Fe—Ni-based compound is difficult to be infiltrated in the solution treatment, which is a process after extrusion, and therefore remains in the final product. Since a coarse compound deteriorates creep characteristics, it is necessary to control the cooling rate so as not to become coarse during the homogenization treatment. Therefore, by setting the average cooling rate after homogenization to 0.01 ° C / s or more, fine Fe-Ni and Cu-Mg compounds are produced, and uniform in the subsequent steps of tensile straightening and aging treatment. Moreover, an aluminum alloy extruded material having excellent heat resistance can be obtained by producing fine precipitates. Here, the “coarse compound” means, for example, a compound that can remain in a particle size (equivalent circle diameter) of 20 μm or more even after extrusion.

Next, the aluminum alloy ingot after cooling is extruded at 310 to 450 ° C. to obtain an intermediate extruded material. The ingot is reheated at the time of extrusion, but it takes time to raise the temperature in the heating furnace, and the crystallized material becomes coarse. Therefore, the extrusion process is performed immediately after the temperature rises with an induction heater (induction heating). Preferably it is done. When the temperature of the extrusion process is less than 310 ° C., the deformation resistance of the material becomes high during the extrusion process, and the extrusion speed becomes slow, so the productivity is lowered. When the temperature of the extrusion process exceeds 450 ° C., dynamic recovery occurs during the extrusion process, and fine subcrystal grains cannot be obtained.

Next, solution treatment and quenching are performed on the intermediate extruded material obtained by the extrusion process. The temperature of the solution treatment is preferably a temperature range that is 3 to 10 ° C. lower than the eutectic melting start temperature. When the temperature of the solution treatment is higher than the above temperature range, the material may be easily eutectic melted due to variations in the furnace temperature. When the temperature of the solution treatment is lower than the above temperature range, solution formation in the structure becomes insufficient, and sufficient strength may not be obtained.

Next, after the solution treatment and quenching, the intermediate extrudate is subjected to 2-4% tension correction within 48 hours. In tension straightening, residual stress is removed and yield strength is improved. In addition, since dislocations are introduced, it becomes possible to make the precipitation of the compound during the subsequent aging treatment fine, and fine subcrystal grains can be maintained even at high temperatures. In particular, by allowing the compound to precipitate finely on the subgrain boundaries, the movement of dislocations is suppressed, and excellent high-temperature creep characteristics can be obtained.

When the time from the solution treatment and quenching to the tensile straightening exceeds 48 hours, the acceleration of precipitation in the portion where the residual stress remains becomes remarkable. Since dislocations are easily introduced in the vicinity of fine precipitates, when precipitation is partially promoted, dislocations introduced by tensile straightening also become partial, and thereafter uniform subcrystal grains cannot be maintained. When the tensile straightening amount (the amount of strain during tensile straightening) is less than 2%, the effect of the above-described tensile straightening becomes small. When the tensile straightening amount exceeds 4%, too many dislocations are introduced and precipitation is promoted, so that the high temperature creep property is deteriorated.

Next, an aging treatment is performed at 160 to 220 ° C. on the intermediate extruded material after tension correction. When the temperature of the aging treatment is less than 160 ° C., the precipitation does not proceed sufficiently. When the temperature of the aging treatment exceeds 220 ° C., the precipitate becomes coarse and sufficient strength cannot be obtained.

Through the above steps, an aluminum alloy extruded material having the above chemical composition and the above structure is obtained.

Hereinafter, examples of the present disclosure will be described in comparison with comparative examples to demonstrate the effects of the present disclosure. These examples show one embodiment of the present disclosure, and the present disclosure is not limited thereto.

First, aluminum alloys (alloys A1 to A14, B1 to B4) having the chemical composition shown in Table 1 were ingoted by continuous casting to obtain billets (ingots adjusted for extrusion) having a diameter of 90 mm. In Table 1, the balance of chemical components is Al and inevitable impurities, and the description thereof is omitted. Moreover, when the content of the chemical component is outside the scope of the present disclosure, it is underlined.

The obtained billet was homogenized at 470 ° C. for 15 hours, cooled at an average cooling rate of 0.012 ° C./s, and then hot extruded at 440 ° C. Thereby, a round bar (intermediate extruded material) having a diameter of 28 mm was obtained. The obtained round bar was subjected to a solution treatment under conditions of 525 ° C. for 2 hours, and after quenching, tensile correction was performed with a strain amount of 2.4% when 190 hours passed, Artificial aging treatment was performed under conditions of 18 hours. In this manner, aluminum alloy extruded materials of Examples 1 to 14 and Comparative Examples 15 to 18 (hereinafter simply referred to as extruded materials) were produced.

For each manufactured extruded material, the maximum particle size (equivalent circle diameter) of the intermetallic compound in the cross section, the density of the intermetallic compound having a particle diameter (equivalent circle diameter) of 0.3 to 20 μm, the average particle diameter of the subcrystalline grains ( The equivalent circle diameter) was measured. Moreover, about each produced extrusion material, the 0.2% yield strength (L direction and LT direction) in room temperature and 200 degreeC was measured by the tension test, and creep resistance (LT direction) was evaluated by the creep rupture test. Hereinafter, measurement and evaluation methods will be described.

<Maximum particle size (equivalent circle diameter) and density of intermetallic compound>
In order to observe the structure of the extruded material in the extrusion direction (L direction), the extruded material is equally divided into two in a direction parallel to the extrusion direction (L direction) (including the central axis of the extruded material). ) The cut surface was polished with water-resistant abrasive paper, and finished to a mirror surface with a buff coated with an abrasive. Next, the central portion of the cut surface of the extruded material (the portion corresponding to the intermediate position in the direction (width direction) perpendicular to the length direction (extrusion direction) in the cut surface) was observed with an optical microscope at 200 times. As a result, the maximum particle size (equivalent circle diameter) of the intermetallic compound and the density of the intermetallic compound having a particle size (equivalent circle diameter) of 0.3 to 20 μm were measured.

<Average grain size of sub-crystal grains (equivalent circle diameter)>
In order to observe the structure of the extruded material in the extrusion direction (L direction), the extruded material is equally divided into two in a direction parallel to the extrusion direction (L direction) (including the central axis of the extruded material). ) The cut surface was polished with water-resistant abrasive paper, and finished to a mirror surface with a buff coated with an abrasive. Thereafter, the cut surface of the extruded material was etched with a Keller solution. Next, the central portion of the cut surface of the extruded material (the portion corresponding to the intermediate position in the direction (width direction) perpendicular to the length direction (extrusion direction) in the cut surface) was observed with an optical microscope at 200 times. Thereby, the average particle diameter (equivalent circle diameter) of the sub-crystal grains was measured.

<0.2% yield strength>
About 0.2% yield strength at room temperature, the test piece was produced using each extrusion material. Specifically, for each extruded material, a test piece in which the extrusion direction (L direction) is the axial direction (length direction) and a test direction in which the direction orthogonal to the extrusion direction (LT direction) is the axial direction (length direction). A piece was made. The test piece had a parallel part diameter of 5 mm, a gauge distance of 15 mm, and a shoulder radius of 10 mm. Next, the test piece was set in a tensile tester, and a tensile test (JIS Z2241 (2011)) was performed at room temperature. Note that, in the tensile test in the LT direction, a common material was friction-welded to both ends of the evaluation portion of the test piece to ensure a necessary length for the test piece. From the result of this tensile test, the 0.2% yield strength (L direction, LT direction) at room temperature was determined. About the evaluation of 0.2% yield strength at room temperature, compared with the conventional (for example, the value disclosed in the above-mentioned Patent Document 2), if the value of 0.2% yield strength at room temperature is 410 MPa or more, it was accepted. .

For the 0.2% yield strength at 200 ° C., a test piece similar to the 0.2% yield strength at room temperature described above was prepared using each extruded material. Subsequently, it heated to 200 degreeC in the state set to the tensile tester. After reaching 200 ° C. for 10 minutes, a tensile test (JIS Z2241 (2011)) was performed. From the result of this tensile test, 0.2% yield strength (L direction, LT direction) at 200 ° C. was determined. For the evaluation of 0.2% yield strength at 200 ° C., compared to the conventional case (for example, the value disclosed in Patent Document 2 above), when the value of 0.2% yield strength at 200 ° C. is 310 MPa or more, it passes. It was.

<Creep resistance>
Using each extruded material, similarly to the measurement of the 0.2% yield strength described above, a test piece was produced in which the direction orthogonal to the extrusion direction (LT direction) was the axial direction (length direction). Subsequently, it heated to 200 degreeC in the state which set the test piece to the creep rupture tester. After reaching 200 ° C., it was held for 60 minutes, and then a creep rupture test was conducted at 200 ° C. In the creep rupture test, a 200 MPa load was applied to the test piece for 100 hours. The load to be applied was set to 200 MPa on the basis of a value requiring recent high temperature characteristics. Regarding the evaluation of creep resistance (LT direction), a load of 200 MPa was applied, and the test was accepted when it did not break in 100 hours, and rejected when broken.

Table 2 shows the results of the measurement and evaluation. In Table 2, when the numerical value of each item is out of the scope of the present disclosure, it is underlined.
As can be seen from Table 2, since Comparative Examples 15 to 18 were outside the scope of the present disclosure, at least one of 0.2% yield strength and creep resistance was unacceptable.

Specifically, in Comparative Example 15, since the Cu content is small, the 0.2% yield strength (L direction, LT direction) at room temperature does not satisfy the standard value (410 MPa), and is rejected. The 0.2% proof stress (L direction, LT direction) did not satisfy the standard value (310 MPa) and was rejected, and the creep resistance (LT direction) was rejected.

In Comparative Example 16, since the Ni content is low, the density of the intermetallic compound having a particle size of 0.3 to 20 μm is low, and the 0.2% yield strength (L direction, LT direction) at 200 ° C. does not satisfy the standard value. It was rejected and the creep resistance (LT direction) was rejected.

In Comparative Example 17, since the Fe content is small, the 0.2% yield strength (L direction, LT direction) at 200 ° C. does not satisfy the standard value, and the creep resistance (LT direction) is rejected. there were.
In Comparative Example 18, since the Zr content is small, recrystallization occurs, and the 0.2% yield strength (LT direction) at room temperature and the 0.2% yield strength (L direction, LT direction) at 200 ° C. satisfy the standard values. The creep resistance (LT direction) was unacceptable. In addition, the numerical value described in the column of the average particle diameter of the subcrystal grain of Comparative Example 18 in Table 2 is the numerical value of the average particle diameter of the recrystallized grain.

On the other hand, since Examples 1 to 14 are within the scope of the present disclosure, 0.2% yield strength at room temperature (L direction, LT direction), 0.2% yield strength at 200 ° C. (L direction, LT direction) , And creep resistance (LT direction) were all passed. That is, it was found that the aluminum alloy extruded material of the present disclosure is excellent in strength and creep resistance at high temperatures.

Next, an aluminum alloy (alloy A14, see Table 1 for the chemical composition) was ingoted by continuous casting to obtain a billet (diameter 356 mm). The obtained billet was homogenized under predetermined conditions, cooled at a predetermined average cooling rate, and then subjected to hot extrusion under predetermined conditions. Thereby, a round bar material (intermediate extruded material) having a diameter of 58 mm was obtained. The obtained round bar material is subjected to a solution treatment under conditions of 525 ° C. for 2 hours, and after quenching, a predetermined strain amount is subjected to tensile correction when a predetermined time has elapsed, and predetermined conditions are satisfied. The artificial aging treatment was performed. Thus, aluminum alloy extruded materials of Examples 21 to 23 and Comparative Examples 24 to 31 (hereinafter simply referred to as extruded materials) were produced.

Table 3 shows the temperature and time of the homogenization treatment, the average cooling rate, the extrusion processing temperature, the time from solution treatment and quenching to tensile straightening, the amount of strain during tensile straightening, and the temperature and time of aging treatment. It was. In Table 3, when the conditions of each process of the manufacturing method are outside the scope of the present disclosure, they are underlined.

For each of the produced extruded materials, the maximum particle diameter (equivalent circle diameter) of the intermetallic compound in the cross section, the density of the intermetallic compound having a particle diameter (equivalent circle diameter) of 0.3 to 20 μm, and the average particle diameter of the subcrystalline grains (Equivalent circle diameter) was measured. Moreover, about each produced extrusion material, the 0.2% yield strength (L direction and LT direction) in room temperature and 200 degreeC was measured by the tension test, and creep resistance (LT direction) was evaluated by the creep rupture test. These measurement and evaluation methods are the same as described above.

The results of the measurement and evaluation are shown in Table 4. In Table 4, when the numerical value of each item is outside the scope of the present disclosure, it is underlined.
As can be seen from Table 4, in Comparative Examples 24-31, the production method was outside the scope of the present disclosure, so at least one of 0.2% yield strength and creep resistance was unacceptable.

Specifically, since Comparative Example 24 had a small amount of strain at the time of tension correction, 0.2% yield strength (LT direction) at room temperature and 0.2% yield strength (L direction, LT direction) at 200 ° C. The reference value was not satisfied and the test was rejected, and the creep resistance (LT direction) was rejected.

Since Comparative Example 25 had a large amount of strain at the time of tensile correction, the 0.2% yield strength (L direction, LT direction) at 200 ° C. did not satisfy the standard value and failed, and the creep resistance (LT direction) was low. It was a failure.

In Comparative Example 26, since the temperature of the homogenization treatment was low, the density of the intermetallic compound having a particle size of 0.3 to 20 μm was low, and the 0.2% proof stress at 200 ° C. (LT direction) did not satisfy the standard value. It was acceptable and the creep resistance (LT direction) was unacceptable.

In Comparative Example 27, since the temperature of the homogenization treatment was high, the 0.2% proof stress at room temperature (LT direction) and the 0.2% proof stress at 200 ° C. (L direction, LT direction) did not satisfy the standard values. It was acceptable and the creep resistance (LT direction) was unacceptable.

In Comparative Example 28, since the average cooling rate was slow, the density of the intermetallic compound having a grain size of 0.3 to 20 μm was low, the average grain size of the sub-crystal grains was large, and the 0.2% proof stress (L direction, (LT direction) and 0.2% proof stress (L direction, LT direction) at 200 ° C. did not satisfy the standard values and failed, and creep resistance (LT direction) failed.

Comparative Example 29 could not be extruded because the extrusion process temperature was low. For this reason, the extruded material could not be evaluated.
In Comparative Example 30, since the extrusion processing temperature was high, the average grain size of the sub-crystal grains was large, the 0.2% proof stress (LT direction) at 200 ° C. did not satisfy the standard value, and the creep resistance was not satisfied. (LT direction) was rejected.

In Comparative Example 31, since the time from solution treatment and quenching to tensile correction was long, the average grain size of the subcrystalline grains was increased, 0.2% proof stress at room temperature (LT direction), and 0.2 at 200 ° C. The 2% yield strength (LT direction) did not satisfy the standard value and was rejected, and the creep resistance (LT direction) was rejected.

On the other hand, since Examples 21 to 23 are within the scope of the present disclosure, 0.2% yield strength at room temperature (L direction, LT direction), 0.2% yield strength at 200 ° C. (L direction, LT direction) , And creep resistance (LT direction) were all passed. That is, it was found that an aluminum alloy extruded material excellent in strength and creep resistance at high temperatures can be obtained by the method for producing an aluminum alloy extruded material of the present disclosure.

Claims

An aluminum alloy extrusion,
In mass%, Cu: 2.5 to 3.3%, Mg: 1.3 to 2.5%, Ni: 0.50 to 1.3%, Fe: 0.50 to 1.5%, Mn: Chemical composition comprising less than 0.50%, Si: 0.15 to 0.40%, Zr: 0.06 to 0.20%, Ti: less than 0.05%, the balance being Al and inevitable impurities Have
In the cross section, the particle diameter of the intermetallic compound is 20 μm or less in terms of the equivalent circle diameter, and the density of the intermetallic compound having a particle diameter of 0.3 to 20 μm in terms of the equivalent circle diameter is 5 × 10 3 pieces / mm 2 or more, And the aluminum alloy extrusion material whose average particle diameter of a subcrystal grain is 20 micrometers or less in a circle equivalent diameter.
It is a manufacturing method of the aluminum alloy extrusion material according to claim 1,
The aluminum alloy ingot having the chemical composition is homogenized at 400 to 500 ° C.,
Next, the ingot is cooled from the homogenization treatment temperature to a temperature of 200 ° C. or less at an average cooling rate of 0.01 ° C./s or more,
Next, the ingot is extruded at 310 to 450 ° C.,
Next, a solution treatment and quenching are performed on the intermediate extruded material obtained by the extrusion process,
Next, after the solution treatment and quenching, within 48 hours, the intermediate extruded material is subjected to tensile correction with a strain of 2 to 4%,
Next, a method for producing an aluminum alloy extruded material, wherein the intermediate extruded material is subjected to an aging treatment at 160 to 220 ° C.