JP2017043802A - Aluminum alloy extrusion material and manufacturing method therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an aluminum alloy extrusion material excellent in strength and creep resistance at high temperature and a manufacturing method therefor.SOLUTION: An aluminum alloy extrusion material contains, by 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 Al with inevitable impurities. The aluminum alloy extrusion material has particle diameter of an intermetallic compound of 20 μm or less by equivalent circle diameter, density of intermetallic compound with particle diameter of 0.3 to 20 μm by equivalent circle diameter of 5×10/mmor more and average particle diameter of subgrain particle of 20 μm by equivalent circle diameter at a cross section.SELECTED DRAWING: None

Description

  The present invention relates to an aluminum alloy extruded material and a method for producing the same.

  In recent years, from the viewpoint of environmental protection, there has been a demand for improved fuel efficiency of automobile internal combustion engines. 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 to control the electrical conductivity and the average particle diameter of the intermetallic compound 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).

JP-A-1-152237 Japanese Patent Laid-Open 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.

  This invention is made | formed in view of this background, and provides the aluminum alloy extrusion material excellent in the intensity | strength and creep resistance in high temperature, and its manufacturing method.

One aspect of the present invention 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: 0.05% And the balance is made 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. 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 equivalent circle diameter.

  According to this aluminum alloy extruded material, the strength and creep resistance in a high temperature range of, for example, 200 ° C. or higher can be improved. Here, regarding the strength, not only the strength in the extrusion direction (L direction) but also the strength in the direction perpendicular to the extrusion direction (LT direction) can be improved. Further, regarding the creep resistance, the creep resistance in the LT direction can be improved. Thereby, it can apply to components, such as internal combustion engines, such as a motor vehicle used in a high temperature environment, and a supercharger.

  Another aspect of the present invention is a method for producing the aluminum alloy extruded material, wherein the aluminum alloy ingot having the above composition is homogenized at 400 to 500 ° C., and an average cooling rate of 0.01 ° C./s or more. After cooling to a temperature of 200 ° C. or less from the temperature of the homogenization treatment, extrusion is performed at 310 to 450 ° C., and the resulting extruded material is subjected to a solution treatment and quenching, and then within 2 to 4 within 48 hours. % Straightening is performed, and an aging treatment is performed at 160 to 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 automobile internal combustion engine parts, supercharger parts, and the like used in high-temperature environments.

  Hereinafter, embodiments of the present invention will be described. In addition, this invention is not limited to the following embodiment, It cannot be overemphasized that it can implement with a various aspect in the range which does not deviate from the summary of this invention.

<Aluminum alloy extruded material>
The aluminum alloy extruded material is, 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 0.5%, Mn: 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 Consists of impurities. Hereinafter, each component composition of the aluminum alloy extruded material will be described in detail.

Cu: 2.5-3.3%
Cu contributes to improving the strength of the aluminum alloy extruded material at room temperature and high temperature. The Cu content is in the range of 2.5 to 3.3%. 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. Mg content shall be 1.3 to 2.5% of range. 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 material increases during hot working such as extrusion, and the productivity decreases.

Ni: 0.50 to 1.3%
Ni forms an Fe—Ni compound together with Fe and improves the heat resistance of the aluminum alloy extruded material. The Ni content is in the range of 0.50 to 1.3%. 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%, an Ni-based compound such as an Al-Ni-based or Al-Ni-Cu-based material that is dispersed in the matrix phase is formed, so that the effect of improving heat resistance is reduced. . Moreover, by forming a coarse Fe—Ni compound, cracks are likely to occur during hot working such as extrusion, and productivity is lowered.

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. The Fe content is in the range of 0.50 to 1.5%. 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, so that at normal temperature and high temperature. Contributes to improving the strength of extruded aluminum alloys. The Mn content is less than 0.50%. 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, thereby improving the strength of the extruded aluminum alloy material. To improve. The Si content is in the range of 0.15 to 0.40%. 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%, a compound of Mg and Si is formed and the heat resistance is lowered.

Zr: 0.06-0.20%
Zr contributes to refinement of the cast structure. In addition, the fine dispersion of the Al ₃ Zr compound suppresses recrystallization that occurs during the solution treatment and forms fine sub-crystal grains, thereby contributing to an improvement in the strength of the aluminum alloy extruded material. The Zr content is in the range of 0.06 to 0.20%. When the Zr content is less than 0.05%, the effect of making the cast structure fine and improving the strength cannot be obtained sufficiently. 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, Al and inevitable impurities may be basically used, but elements other than the above elements added to the aluminum alloy are generally allowed within a range that does not greatly affect the characteristics.

In addition, in the cross section of the extruded aluminum alloy material, the intermetallic compound particle size is 20 μm or less in terms of the equivalent circle diameter, and the density of the intermetallic compound in which the particle size is 0.3 to 20 μm in terms of the equivalent circle diameter is 5 × 10 ^3. Pieces / mm ² or more, and the average grain size of the sub-crystal grains is 20 μm or less in terms of equivalent circle diameter. Hereinafter, the structure of the aluminum alloy extruded material will be described in detail.

In order to suppress the coarsening of the sub-crystal grain size at high temperature and to realize excellent strength and creep resistance in the structure of the aluminum alloy extruded material, on the sub-grain boundary so that dislocations do not move easily at high temperature. The crystallized product must be finely present. Therefore, the particle diameter of the intermetallic compound in the cross section of the aluminum alloy extruded material is set to 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 is set. 5 × 10 ³ pieces / mm ² or more.

When the particle diameter of the intermetallic compound in the cross section of the aluminum alloy extruded material exceeds 20 μm in terms of the equivalent circle diameter, it becomes a starting point at the time of fracture, and the strength decreases. In the cross section of the aluminum alloy extruded material, when the density of the intermetallic compound having a diameter equivalent to a circle 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 at high temperatures, especially the direction perpendicular to the extrusion direction (LT direction), the average grain size of the sub-crystal grains in the cross section of the aluminum alloy extruded material is equivalent to a circle in the structure of the aluminum alloy extruded material. The diameter is 20 μm or less. When the average grain size of the sub-crystal grains in the cross section of the aluminum alloy extruded material exceeds 20 μm in the equivalent circle diameter, the effect of improving the strength at a 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 diameter (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 particle diameter (equivalent circle diameter) of the subcrystalline grains are aluminum alloys. It can be determined by observing an arbitrary region excluding a surface layer portion (for example, a range of 2 to 5 mm from the surface) with an optical microscope or the like, which is a cross section in a predetermined direction in the extruded material.

<Method for producing aluminum alloy extruded material>
The method for producing an aluminum alloy extruded material is to homogenize an ingot of aluminum alloy having the above composition at 400 to 500 ° C., and at an average cooling rate of 0.01 ° C./s or more, the temperature of the homogenization treatment is 200 ° C. or less. After cooling to a temperature, extrusion processing is performed at 310 to 450 ° C., and a solution treatment and quenching are performed on the obtained extruded material, and then 2 to 4% strain correction is performed within 48 hours, and 160 to 220 Aging is performed at ℃. Hereinafter, the manufacturing method of an aluminum alloy extruded material will be described in detail.

  In producing the aluminum alloy extruded material, first, the aluminum alloy is melted by a conventional method, and the ingot of the ingot aluminum alloy (billet: ingot adjusted for extrusion) is homogenized at 400 to 500 ° C. Process (homogenization process). The aluminum alloy having the above composition is: 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%, the balance being Al and inevitable impurities An aluminum alloy consisting of The temperature of the homogenization treatment is in the range of 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 (billet) of the aluminum alloy after the homogenization treatment is cooled from the homogenization treatment temperature to a predetermined temperature of 200 ° C. or less at an average cooling rate of 0.01 ° C./s or more (cooling step). Here, when the average cooling rate is A ° C. and the time required for cooling the ingot (billet) from A ° C. to 200 ° C. is B seconds, (A ° C.−200 ° C.) / Expressed in B seconds. 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 the Fe—Ni-based compound grow coarsely during cooling.

  For example, when a low temperature extrusion process at 450 ° C. or less is performed in a state where a coarse compound is formed, dislocations introduced by the extrusion process disappear 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 the homogenization treatment to 0.01 ° C./s or more, fine Fe—Ni-based and Cu—Mg-based compounds are generated, and are 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 ingot (billet) of the aluminum alloy after cooling is extruded at 310 to 450 ° C. to obtain an extruded material (intermediate extruded material) (extrusion process). The ingot (billet) is reheated during the extrusion process, but it takes time to raise the temperature in the heating furnace, and the crystallized material becomes coarse, so immediately after the temperature rises with an induction heater (induction heating) etc. Extrusion is preferably performed. The extrusion temperature is 310 to 450 ° C. 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 obtained extruded material (intermediate extruded material) (solution treatment / quenching step). The temperature of the solution treatment is preferably a temperature range 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 solution treatment and quenching, 2 to 4% tensile correction is performed on the extruded material (intermediate extruded material) within 48 hours. In tension straightening, residual stress is removed and yield strength is improved. Further, since dislocations are introduced, it becomes possible to make fine precipitation during subsequent aging treatment, and fine subcrystal grains can be maintained even at high temperatures. In particular, by causing fine precipitation on the subgrain boundaries, the movement of dislocations is suppressed, and excellent high temperature creep characteristics can be obtained.

  In the case where the time from the solution treatment and quenching to the tensile correction exceeds 48 hours, the acceleration of precipitation in the portion where the residual stress remains is significant. 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 on the extruded material (intermediate extruded material) after tensile correction at 160 to 220 ° C. (aging treatment process). 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, the density of an intermetallic compound having the above composition (in the cross section, the particle diameter of the intermetallic compound is equivalent to a circle equivalent diameter of 20 μm or less and the particle diameter is a circle equivalent diameter of 0.3 to 20 μm). 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).

  Examples of the present invention will be described below in comparison with comparative examples to demonstrate the effects of the present invention. These examples show one embodiment of the present invention, and the present invention is not limited to these examples.

  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 (diameter 90 mm). In Table 1, the balance of chemical components is Al and inevitable impurities, and the description thereof is omitted. Moreover, when a chemical component was outside the scope of the present invention, it was 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. By the above, the aluminum alloy extrusion material of Examples 1-14 and Comparative Examples 15-18 (henceforth an appropriate extrusion material only hereafter) was produced.

  About each produced extrusion material (Examples 1-14, Comparative Examples 15-18), the maximum particle size (equivalent circle diameter) and particle size (equivalent circle diameter) of the intermetallic compound in the cross section are 0.3 to 20 μm. The density of the intermetallic compound and the average grain size (equivalent circle diameter) of the sub-crystal grains were 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>
Cut the extruded material so that the structure in the extrusion direction (L direction) can be observed, so that the extruded material is equally divided into two (including the central axis of the extruded material) in a direction parallel to the extrusion direction (L direction). The cut surface was polished with water-resistant abrasive paper, and further mirror finished 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. Thereby, the maximum particle diameter (equivalent circle diameter) of the intermetallic compound and the density of the intermetallic compound having a particle diameter (equivalent circle diameter) of 0.3 to 20 μm were measured.

<Average grain size of sub-crystal grains (equivalent circle diameter)>
Cut the extruded material so that the structure in the extrusion direction (L direction) can be observed, so that the extruded material is equally divided into two (including the central axis of the extruded material) in a direction parallel to the extrusion direction (L direction). The cut surface was polished with water-resistant abrasive paper, and further mirror finished 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. Regarding the evaluation of 0.2% proof stress at room temperature, the 0.2% proof stress value at room temperature was 410 MPa or more as compared with the conventional one (for example, the value disclosed in Patent Document 2).

  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. 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, 0.2% yield strength (L direction, LT direction) at 200 ° C. was determined. For the evaluation of 0.2% yield strength at 200 ° C., the value of 0.2% yield strength at 200 was 310 MPa or more as compared with the past (for example, the value disclosed in Patent Document 2 above). .

<Creep resistance>
A test piece similar to the 0.2% proof stress described above was produced using each extruded material. 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 that was 200 MPa was applied and the sample was not broken in 100 hours was accepted, and the broken sample was rejected.

Table 2 shows the results of the measurement and evaluation. In Table 2, when the numerical value of each item is outside the scope of the present invention, it is underlined.
As can be seen from Table 2, Comparative Examples 15 to 18 were outside the scope of the present invention, so that 0.2% proof stress and creep resistance were not good.

  Specifically, in Comparative Example 15, since the Cu content of the alloy component is small, the 0.2% yield strength (L direction, LT direction) at room temperature does not satisfy the reference value (410 MPa or more), and at 200 ° C. The 0.2% yield strength (L direction, LT direction) did not satisfy the standard value (310 MPa or more), and the creep resistance (LT direction) was not acceptable.

  In Comparative Example 16, since the Ni content of the alloy component is small, the density of the intermetallic compound having a particle size of 0.3 to 20 μm is low, and the 0.2% proof stress (L direction, LT direction) at 200 ° C. is the reference value. The creep resistance (LT direction) was not acceptable.

In Comparative Example 17, since the Fe content of the alloy component 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 not acceptable. It was.
In Comparative Example 18, since the Zr content of the alloy component is small, recrystallization occurs, and 0.2% proof stress at room temperature (LT direction) and 0.2% proof stress at 200 ° C. (L direction, LT direction) are standards. The value was not satisfied and 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 1-14 are within the scope of the present invention, 0.2% yield strength at room temperature (L direction, LT direction), 0.2% yield strength at 200 ° C. (L direction, LT direction) In addition, necessary properties were obtained for creep resistance (LT direction). That is, it turned out that the aluminum alloy extruded material of the present invention is excellent in strength and creep resistance at high temperatures.

  Next, an aluminum alloy (alloy A14, see Table 1 for 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. By the above, the aluminum alloy extrusion material (extrusion material) of Examples 21-23 and Comparative Examples 24-31 was 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 invention, they are underlined.

  About each produced extrusion material (Examples 21-23, Comparative Examples 24-31), the maximum particle size (equivalent circle diameter) and particle size (equivalent circle diameter) of the intermetallic compound in the cross section are 0.3 to 20 μm. The density of the intermetallic compound and the average grain size (equivalent circle diameter) of the sub-crystal grains were 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 invention, 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 invention, so that 0.2% proof stress and creep resistance were not good.

  Specifically, since Comparative Example 24 had a small amount of strain during 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 creep resistance (LT direction) was rejected.

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

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

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 increased, and the 0.2% yield strength (LT direction) at 200 ° C. did not satisfy the standard value, and the creep resistance (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 sub-crystal grains increased, 0.2% yield strength at room temperature (LT direction), and 0.2% proof stress at 200 ° C. The 2% yield strength (LT direction) did not satisfy the standard value, and the creep resistance (LT direction) was rejected.

  On the other hand, since Examples 21-23 are within the scope of the present invention, 0.2% yield strength at room temperature (L direction, LT direction), 0.2% yield strength at 200 ° C. (L direction, LT direction) In addition, necessary properties were obtained for creep resistance (LT direction). 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 invention.

Claims (2)

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: Less than 0.50%, Si: 0.15 to 0.40%, Zr: 0.06 to 0.20%, Ti: less than 0.05%, the balance consisting of Al and inevitable impurities,
In the cross section, the particle size 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 size of 0.3 to 20 μm in terms of the equivalent circle diameter is 5 × 10 ³ pieces / mm ² or more, And the average particle diameter of a subcrystal grain is 20 micrometers or less in an equivalent circle diameter, The aluminum alloy extrusion material characterized by the above-mentioned. It is a manufacturing method of the aluminum alloy extrusion material according to claim 1,
The ingot of the aluminum alloy having the above composition is homogenized at 400 to 500 ° C., and cooled from the temperature of the homogenizing process to a temperature of 200 ° C. or less at an average cooling rate of 0.01 ° C./s or more. Extrusion at 450 ° C, solution treatment and quenching of the resulting extruded material, followed by 2-4% strain straightening within 48 hours and aging at 160-220 ° C A method for producing an extruded aluminum alloy material.