JP2007009273A - Plastic-worked article made from aluminum alloy, manufacturing method therefor, automotive parts, aging treatment furnace, and system for manufacturing plastic-worked article made from aluminum alloy - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a plastic-worked article which is made from an Al-Mg-Si-based alloy containing an increased amount of Cu, has higher strength and improved corrosion resistance, and is lightweight by thinning the wall of parts but suppressing a weight loss due to corrosion. <P>SOLUTION: The plastic-worked article manufactured from an ingot of the Al-Mg-Si-based aluminum alloy which contains 1 wt.% or less Cu and has conductivity controlled so as to be larger than the conductivity at the peak aging point by a value between 0 and 1 IACS%. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an aluminum alloy plastic processed product manufactured from an ingot of an Al-Mg-Si-based aluminum alloy, a manufacturing method thereof, an automotive part, an aging furnace, and an aluminum alloy plastic processed product manufacturing system.

  In recent years, aluminum alloy plastic processed products have been used as structural materials (parts) for transportation equipment such as vehicles, ships, aircraft, automobiles, and motorcycles that require high strength and corrosion resistance.

  As an example of aluminum alloy plastic processed products for structural materials for transport aircraft, automotive parts such as suspension arms are excellent in workability and have high strength and corrosion resistance for the purpose of reducing the weight of the car body. Alloy plastic processed products are used. Although A6061 is frequently used as an Al—Mg—Si based alloy, high strength is demanded in order to further reduce the weight, and the material side of the aluminum alloy is improved.

In order to increase the strength of the Al—Mg—Si based alloy, the amount of excess Si and the amount of Cu element added are increased. In particular, the Cu element promotes the precipitation of Mg ₂ Si and makes a solid solution in the matrix and greatly contributes to improving the strength. Therefore, increasing the amount of addition is an effective means for increasing the strength.

  However, when the amount of Cu element added for increasing the strength is 0.05% or more, the susceptibility to intergranular corrosion increases, and stress corrosion cracking may occur when used in a corrosive environment.

  In the prior art, by adding transition elements such as Mn, Cr, Zr, etc., grain size corrosion and stress corrosion cracking are prevented by refining the crystal grain size and crystallization, and Al-Mg-Si based alloys It is known to improve the corrosion resistance.

For example, the following is disclosed in Patent Document 1 below. For the purpose of providing a high-strength, high-toughness aluminum alloy forged material, Mg: 0.6 to 1.6% (mass%, the same applies hereinafter), Si: 0.6 to 1.8%, Cu: 0.05 -1.0% and Fe is restricted to 0.30% or less, Mn: 0.15-0.6%, Cr: 0.1-0.2%, Zr: 0.1-0. It is an aluminum alloy forging containing 2% or more, and hydrogen: 0.25 cc / 100 g Al or less, the balance being Al and inevitable impurities, and casting at a cooling rate of 10 ° C./sec or more The obtained aluminum alloy ingot was subjected to homogenization heat treatment at a temperature of 530 to 600 ° C. and then hot forged into a forged material. Mg ₂ Si and Al—Fe—Si— ( (Mn, Cr, Zr) system crystallized area ratio It has been proposed to 1.5% or less per unit area.
JP 2000-144296 A

The following is disclosed in Patent Document 2 below. For the purpose of providing an Al alloy forged material having high strength and high toughness, and excellent in corrosion resistance and durability, Mg: 0.6 to 1.8% (mass%, the same applies hereinafter), Si: 0.6 -1.8%, and further includes one or two of Cr: 0.1-0.2% and Zr: 0.1-0.2%, Cu: 0.25% or less, Mn: 0.05% or less, Fe: 0.30% or less, hydrogen: 0.25 cc / 100 g Al or less, each of which is a forged aluminum alloy composed of Al and unavoidable impurities, the grain boundary of the aluminum alloy structure The average particle size of Mg ₂ Si and Al—Fe—Si— (Mn, Cr, Zr) -based crystal precipitates (crystallized products and precipitates) present on the crystal is 1.2 μm or less. It has been proposed that the average distance between each other is 3.0 μm or more. .
JP 2001-107168 A

Further, Patent Document 3 below discloses the following. For the purpose of providing an Al alloy forged material having high strength and high toughness, and excellent in corrosion resistance and durability, Mg: 0.6 to 1.8% (mass%, the same applies hereinafter), Si: 0.6 -1.8%, and further includes one or two of Cr: 0.1-0.2% and Zr: 0.1-0.2%, Cu: 0.25% or less, Mn: 0.05% or less, Fe: 0.30% or less, Hydrogen: 0.25 cc / 100 g Al or less, each of which is an aluminum alloy forging made of Al and unavoidable impurities, on the grain boundaries of the aluminum alloy structure The average particle size of Mg ₂ Si and Al—Fe—Si— (Mn, Cr, Zr) based crystal precipitates present in the crystal is 1.2 μm or less, and the average interval between these crystal precipitates is 3.0 μm or more. And the natural potential of the aluminum alloy forging It has been proposed that the minimum value of -1020 mV or more.
JP 2002-294382 A

  However, these Al—Mg—Si based alloy materials can prevent intergranular corrosion and refine stress corrosion cracking by refining the crystal grain size and crystallized material. Corrosion resistance deteriorates due to an increase in the amount added, and the resulting corrosion weight loss cannot be suppressed. For plastic processed products whose parts are thinned to reduce weight, there is a risk that the strength will decrease and the durability will deteriorate due to the thinned thickness due to corrosion weight loss. There is a problem that it is not suitable.

On the other hand, it has been known that the electrical conductivity on the surface of an aluminum alloy material varies greatly depending on the structure of the aluminum alloy material, the solid solution and the precipitation state of the precipitate, and is closely correlated with the hardness and strength of the aluminum alloy material. For example, the following Patent Document 4 describes the relationship between the electrical conductivity (IACS (International Annealed Copper Standard)%) and strength (MPa) of the Al alloy forging surface, as shown in FIG. It shows that the intensity is maximum when it is within the predetermined range.
Japanese Patent Laid-Open No. 2004-43907

  And this patent document 4 discloses the following. 6000 series Al alloy forgings and forgings that can stably obtain 0.2% proof stress of 350 MPa or more even if the strength of the forging material is increased by increasing the amount of alloying elements and is thinned. For the purpose of providing materials, Mg: 0.6-1.8% (mass%, the same applies hereinafter), Si: 0.8-1.8%, Cu: 0.2-1.0% included The mass ratio of Si / Mg is 1 or more, and Mn: 0.1 to 0.6%, Cr: 0.1 to 0.2%, and Zr: 0.1 to 0.2%. It is an aluminum alloy forging material that contains more than seeds and the balance is Al and inevitable impurities, and the electrical conductivity of the surface of the aluminum alloy forging material after artificial age hardening is 41.0 to 42.5 IACS%. Proposed. This is by utilizing the relationship between the electrical conductivity and strength shown in FIG. 7, and controlling the electrical conductivity of the surface of the aluminum alloy forged material after the artificial age hardening treatment to a range of 41.0 to 42.5 IACS%. It is guaranteed that 0.2% proof stress is stably obtained at 350 MPa or more.

  However, as in Patent Document 4, it is effective for strength evaluation to control the conductivity within a certain range such as 41.0 to 42.5 IACS%. It does not solve the problem, that is, the corrosion resistance deteriorates due to an increase in the amount of Cu added and corrosion weight loss occurs, but it does not solve the corrosion resistance evaluation of plastic parts with a thin part shape, that is, corrosion weight loss evaluation. Nothing is stated about.

  Under the circumstances as described above, it is desired to impart high strength to the Al-Mg-Si based aluminum alloy plastic processed product with an increased amount of Cu addition and to improve the corrosion resistance.

  The present invention was proposed in view of the above, and in an Al-Mg-Si alloy plastic processed product with an increased amount of Cu added, it is possible to improve the corrosion resistance as well as increase the strength, and even if the part is thinned An object of the present invention is to provide an aluminum alloy plastic processed product that can prevent weight loss and reliably reduce weight, a manufacturing method thereof, an automobile part, an aging furnace, and a manufacturing system of an aluminum alloy plastic processed product. And

  1) In order to achieve the above object, according to a first aspect of the present invention, in an aluminum alloy plastic processed product manufactured from an ingot of an Al-Mg-Si-based aluminum alloy, Cu is contained in an amount of 1% by mass or less, and conductivity is increased. Is characterized by having an increment of greater than 0 and less than or equal to 1 IACS% relative to the conductivity at peak aging.

  2) In the second invention, in addition to the configuration of the invention described in the above item 1), the conductivity has an increment of greater than 0 and less than or equal to 0.7 IACS% with respect to the conductivity at the time of peak aging. It is characterized by that.

  3) In addition to the configuration of the invention described in 1) or 2) above, the third invention contains 1% by mass or less of Cu, 0.8 to 1.15% by mass of Mg, Si 0.95 to 1.15 mass%, Mn 0.4 to 0.6 mass%, Fe 0.2 to 0.3 mass%, Cr 0.11 to 0.19 mass%, Zn 0 .25% by mass or less, Zr 0.05% by mass or less, Ti 0.012-0.035% by mass, B 0.0001-0.03% by mass or less, and the remainder consisting of Al and inevitable impurities It is characterized by that.

  4) In the fourth aspect of the invention, in addition to the configuration of the invention described in any one of the above items 1) to 3), the aging treatment time after the peak aging time in the artificial age hardening treatment is controlled. It is characterized by being obtained.

  5) In the fifth aspect of the invention, in addition to the configuration of the invention described in any one of items 1) to 4), the peak aging time depends on the aging treatment time during the artificial age hardening treatment. It is characterized by the fact that the aging treatment time required for the hardness to increase and reach a peak is reached.

  6) In the sixth aspect of the invention, in addition to the configuration of the invention described in any one of items 1) to 4), the peak aging time point has a hardness with aging treatment time × temperature as a horizontal axis. It is characterized by being the maximum time.

  7) In the seventh invention, in addition to the configuration of the invention described in any one of items 1) to 4), the peak aging time depends on the aging treatment time during the artificial age hardening treatment. It is a point in time when the conductivity starts increasing after the conductivity increases.

  8) The eighth invention is characterized in that, in addition to the configuration of any one of the above-described items 1) to 7), the aluminum alloy plastic processed product is an automotive part. .

  9) A ninth invention relates to a method of manufacturing an aluminum alloy plastic processed product, wherein an aluminum alloy plastic processed product is manufactured from an ingot of an Al-Mg-Si-based aluminum alloy. Casting melt, casting product obtained by the above melt casting is subjected to homogenization processing and plastic working, plastic processing product obtained by the above plastic processing is subjected to solution treatment, water quenching treatment and artificial age hardening treatment, The aging treatment time after the peak aging time in the artificial age hardening treatment is controlled so that the electrical conductivity of the plastic processed product has an increment of greater than 0 and less than 1 IACS% with respect to the electrical conductivity at the peak aging time. It is characterized by that.

  10) In the tenth invention, in addition to the configuration of the invention described in the above item 9), the artificial age hardening treatment has an aging treatment temperature of 170 ° C. or more and 210 ° C. or less, and an aging treatment time of 0.5 hour or more. It is characterized by being 18 hours or less.

  11) In the eleventh aspect of the invention, in addition to the structure of the invention described in the above item 9) or 10), the solution treatment is performed at a temperature of 530 ° C. or more and 560 ° C. or less, and the water quenching treatment is performed at a temperature of Is performed at 70 ° C. or lower.

  12) In the twelfth aspect of the invention, in addition to the configuration of the invention described in any one of items 9) to 11), the plastic working is one type selected from extrusion, forging, and rolling. Or it is the combination of 2 or more types.

  13) The thirteenth invention is an automotive part, which is obtained by using the method for manufacturing an aluminum alloy plastic processed product according to any one of items 9) to 12) above. It is said.

  14) A fourteenth aspect of the present invention is an aging furnace used for artificial age hardening treatment in producing an aluminum alloy plastic work product from an ingot of an Al-Mg-Si based aluminum alloy. It is characterized in that the aging treatment time after the peak aging time in the artificial age hardening treatment is controlled so that the conductivity has an increment of greater than 0 and less than 1 IACS% with respect to the conductivity at the peak aging time.

  15) A fifteenth aspect of the present invention is a manufacturing system for an aluminum alloy plastic processed product, characterized in that it has the aging furnace described in item 14) above.

  According to the present invention, in an aluminum alloy plastic processed product manufactured from an ingot of an Al-Mg-Si-based aluminum alloy, Cu is contained in an amount of 1% by mass or less, and the conductivity is higher than the conductivity at the time of peak aging. Therefore, even if it is a plastic work product of an Al—Mg—Si based alloy with an increased amount of Cu added, it is possible to suppress the weight loss of corrosion. Corrosion resistance can be improved with increasing strength. Therefore, even if the part is thinned, the weight can be reliably reduced by suppressing the corrosion weight loss, and the use of the Al-Mg-Si alloy plastic work product for transportation equipment can be further expanded. It becomes like this.

  In the plastic processed product of Al-Mg-Si alloy, the present inventors can increase the strength of the material when the amount of Cu in the composition is increased, while the corrosion resistance is deteriorated, resulting in pores. Corrosion weight loss due to corrosion (pitting) is likely to occur. However, by over-aging the artificial age hardening treatment (hereinafter referred to as “aging treatment”), corrosion weight loss due to pitting corrosion can be suppressed, and the corrosion resistance is increased with increasing strength. I found out that it can be improved.

  In other words, when the aging treatment time is changed, the plasticity processed product of Al-Mg-Si alloy has a certain relationship among hardness, conductivity, and corrosion weight loss, and the conductivity at the time of peak aging is As a reference, the strength property can be obtained even in the overaging treatment by performing the aging treatment so that the increment X of the conductivity is in the range of 0 <X ≦ 1IACS%, preferably 0 <X ≦ 0.7IACS%. The present invention was completed by discovering that the corrosion weight loss can be suppressed and the corrosion resistance can be improved while maintaining.

  Here, the peak aging time is the time when the aging time required for the hardness to increase and reach the peak in the aging treatment according to the aging time. Or it can also be set as the time when hardness becomes the maximum, with aging treatment time x temperature as the horizontal axis. Furthermore, it can be set as the time when the electrical conductivity increases in accordance with the aging time during the artificial age hardening treatment, and starts to show a certain value, for example, when the differential value of the conductivity becomes a certain value or less. This is because the corrosion resistance can be improved by using these time points as a reference.

  Overaging treatment refers to performing aging treatment by taking more time beyond the peak aging point.

IACS% is the ratio of the electrical conductivity of a material having a unit length and unit cross-sectional area to the electrical conductivity of international standard soft copper (see JI5600). Volume resistance of international standard soft copper at 20 ° C. The rate (1.7241 μΩm × 10 ⁻² ) is divided by the volume resistivity of the material to be measured and calculated as a percentage.

  The present invention proposes a method for evaluating not only the strength of an Al—Mg—Si alloy plastic work product but also the corrosion resistance by conductivity.

  FIG. 1 is a diagram showing the relationship between the aging treatment time and the electrical conductivity when an aging treatment is performed at 200 ° C. on an Al—Mg—Si alloy plastic work product. Regardless of the alloy composition, in the aging treatment of plastic processed products of Al-Mg-Si alloys, the aging treatment time and the conductivity show a curve relationship as shown in FIG. 1, and the conductivity depends on the aging treatment time. Although it increases relatively quickly, it shows a tendency to rise constant or slightly in a few hours after reaching a certain value, and then turn to increase again.

  FIG. 2 is a diagram showing the relationship between the aging treatment time and the hardness when a plastic work product of an Al—Mg—Si alloy is subjected to aging treatment at 200 ° C. Regardless of the alloy composition, in the aging treatment of plastic processed products of Al-Mg-Si alloy, the aging treatment time and hardness show a curve relationship as shown in FIG. 2, and the hardness is the highest hardness according to the aging treatment time. Although it increases rapidly until reaching the maximum hardness, it remains almost constant for several hours after reaching the maximum hardness, and then tends to decrease.

  The present inventors prepared samples with various values of electrical conductivity according to various aging treatment times by performing an aging treatment on an Al-Mg-Si alloy plastic work product, and pitting corrosion ( Corrosion weight loss by pitting) was investigated. As a result, in samples where the increase in conductivity is within the specified range based on the conductivity at the time of peak aging, corrosion weight loss due to pitting corrosion can be suppressed, corrosion resistance can be improved, and overaging. It has been found that strength reduction due to treatment can be prevented. The control of the conductivity by this aging treatment is particularly effective when applied to an Al—Mg—Si based alloy with an increased amount of Cu element added.

  In the present invention, the aging treatment time for improving the corrosion resistance can be appropriately determined by measuring the conductivity increment X with reference to the conductivity at the time of peak aging. When determining the aging treatment time for improving the corrosion resistance, when using hardness measurement, the relationship between the aging treatment time and the hardness is substantially symmetrical with respect to the peak aging point as shown in FIG. Therefore, it is difficult to distinguish subaging (before peak aging time) and overaging (after peak aging time) from the hardness value, and it is difficult to appropriately determine the aging treatment time for improving corrosion resistance. On the other hand, in the present invention, by utilizing the relationship between the aging treatment time and the conductivity shown in FIG. 1 and measuring the increment of the conductivity based on the conductivity at the peak aging time, the aging treatment time for improving the corrosion resistance. Determine appropriately. This makes it possible for the first time to accurately evaluate the corrosion resistance (corrosion weight loss) of a plastic work product of an Al—Mg—Si alloy.

  In the present invention, as described above, the conductivity increment X is in the range of 0 <X ≦ 1IACS%, preferably 0 <X ≦ 0.7IACS%, based on the conductivity at the peak aging point in the aging treatment. Specified as a range. As a result, the corrosion resistance of the plastic processed product is greatly improved, strength reduction due to overaging treatment can be prevented, and high strength can be maintained.

  Compared to hardness measurement, conductivity measurement is non-destructive and easy to measure, and can be measured in real time on the spot, thus providing a great merit in product quality control.

  The electrical conductivity does not always show a constant value due to variations in manufacturing conditions even in a plastic processed product having the same alloy composition, but the relationship between the aging treatment time and the electrical conductivity shown in FIG. 1 does not change. Therefore, as long as the time to reach peak aging is measured in advance, the conductivity near the peak aging can be measured in real time, and the increment of conductivity based on the conductivity of the peak aging can be measured. . Thus, it is possible to appropriately determine whether or not the current time is an aging treatment time during which the corrosion resistance is improved during the aging treatment, and the aging treatment can be continued, terminated, and condition changed based on the determination result.

  As an example of measuring conductivity in real time, an electrical conductivity measurement terminal is introduced into the heat treatment furnace, an aging treatment is performed in a state where the plastic processed product and the terminal are fixed in contact, and the change in electrical conductivity over time is measured. do it. In addition, during the aging treatment, the plastic processed product may be taken out from the heat treatment furnace and cooled, and the conductivity may be measured with the measurement temperature kept constant. By these methods, it is possible to determine in real time whether the current time is the aging treatment time when the corrosion resistance of the plastic workpiece is improved, and the required strength and corrosion resistance can be reliably obtained. This is a great merit of quality control.

  The preferable manufacturing method of the aluminum alloy plastic work product in this invention is demonstrated.

  The aluminum alloy in the present invention is an Al—Mg—Si based aluminum alloy, and the content of Cu is 1% by mass or less. Besides, Mg is 0.8 to 1.15% by mass, Si is 0.95 to 1.15% by mass, Mn is 0.4 to 0.6% by mass, Fe is 0.2 to 0.3% by mass, Cr is 0.11-0.19 mass%, Zn is 0.25 mass% or less, Zr is 0.05 mass% or less, Ti is 0.012-0.035 mass%, and B is 0.0001-0. The content is preferably 03% by mass or less, and the remainder is composed of Al and inevitable impurities.

  The plastic processed product itself is manufactured by a known standard method or an improved method thereof except that the conductivity increment X is controlled within the range of 0 <X ≦ 1IACS% based on the conductivity at the peak aging point in the aging treatment. Is possible. For example, when casting a molten and adjusted aluminum alloy melt within the above-mentioned aluminum alloy component range, any of the casting methods such as continuous casting rolling method, semi-continuous casting method (DC casting method), hot top casting method, etc. You may choose and cast. However, in melt casting, in order to obtain a sound ingot, casting is preferably performed at a casting temperature of 750 ± 50 ° C. and a casting speed of 240 ± 50 mm / min.

  Next, the obtained ingot is preferably subjected to a homogenization treatment at 470 ° C to 540 ° C. This is because by performing the homogenization treatment within this range, the ingot is sufficiently homogenized and the solute atoms are sufficiently infused, so that the strength required by the subsequent aging treatment can be obtained. The holding time can be 3 to 10 hours.

  Then, plastic processing is performed after the homogenization processing, and processing is performed to a predetermined size by machining as necessary. As the plastic processing method, a conventional plastic processing method can be used as long as the heating temperature of the raw material during processing is set to a predetermined range. For example, it is a processing method such as extrusion, forging and rolling, but it is necessary to suppress recrystallization of the structure after processing in order to improve the strength. The heating temperature of the material is set to [430 + plastic processing rate ( %)] It is desirable to control within a range of from 0 ° C. to 550 ° C. By setting the temperature at which the plastic working rate is set as a condition, the occurrence of coarse recrystallization can be further suppressed, and the strength can be further improved by the subsequent aging treatment. The definition of the plastic working rate will be explained. For example, in the case of extrusion, [(cross-sectional area subject to deformation) ÷ (initial cross-sectional area) × 100] (%), which is a kind of upsetting process of forging In such a case, [(deformed height) ÷ (initial height) × 100] (%). Further, the processing rate of a plastic processed product that undergoes a plurality of steps in multiple stages is defined as the plastic processing rate for the final shape. The processing rate of a plastic workpiece having a complicated shape is calculated by the above formula for each part, and the average value is defined as the plastic processing rate.

  After plastic working, solution treatment, water quenching, and aging treatment are performed. This is because, for example, strength and corrosion resistance required for a structural material (part) of a transport device such as a vehicle, a ship, an aircraft, an automobile, or a motorcycle according to the application are obtained.

The solution treatment is preferably in the range of 530 to 560 ° C. If the solution temperature is less than 530 ° C., Mg ₂ Si or the like does not sufficiently dissolve, and the strength required by subsequent aging treatment may not be obtained. If the solution temperature exceeds 560 ° C., burning (local dissolution) may occur. The holding time can be 2 to 6 hours.

  The water quenching treatment after the solution treatment is preferably performed under conditions where the water temperature is 70 ° C. or less. Further, the quenching treatment is preferably water cooling, and when the quenching temperature exceeds 70 ° C., the quenching effect cannot be obtained, and the necessary strength may not be obtained by the subsequent aging treatment.

  The aging treatment is carried out so that the increment X of conductivity is in the range of 0 <X ≦ 1IACS%, preferably in the range of 0 <X ≦ 0.7IACS%, based on the conductivity at the time of peak aging. To control. In order to obtain the required strength and corrosion resistance, for example, it is preferable to set the aging treatment temperature within the range of 170 to 210 ° C. and the aging treatment time within the range of 0.5 to 18 hours. If the aging treatment temperature is less than 170 ° C., the aging effect is not promoted and the required strength may not be obtained. On the other hand, when the aging treatment temperature exceeds 210 ° C., aging is promoted too much and the strength may be lowered. The aging treatment is preferably performed within 1 hour after the solution treatment in order to promote the aging effect and obtain a required strength.

  Plastic processed products are further machined as necessary, for example, cutting, bending, drawing, etc., for structural materials (parts) of transportation equipment such as vehicles, ships, aircraft, automobiles, and motorcycles. Finished.

  The structure of the melt-cast aluminum alloy ingot will be described. The size of the crystal grain size of the ingot greatly affects the strength of the processed product when plastic processing and subsequent aging treatment are performed. If the crystal grain size of the original ingot is large, strength improvement after plastic working cannot be obtained. Therefore, the crystal grain size must be 300 μm or less on average, and preferably 250 μm or less. . The crystal grain size can be measured by, for example, a section method on an optical micrograph.

  If the size of DAS (Dendrite Arm Space) of the ingot exceeds 40 μm, the strength when plastic working and subsequent aging treatment is reduced, the average value must be 40 μm or less. Preferably it is 20 μm or less. The size of DAS is described in, for example, “Light Metal (1988), vol. 38, no. 1, p. 45 ”can be measured according to the“ Dendrite arm spacing measurement method ”.

The ingot crystallized product, the crystallized product referred to in the present invention, is an AlMnSi phase, Mg ₂ Si phase, secondary phase containing Fe and Cr crystallized in the form of particles or flakes at the crystal grain boundary. If the average particle size of the crystallized product is 8 μm or less, it does not affect the plastic workability, so it is necessary to make it 8 μm or less, preferably 6.8 μm or less. The size of the crystallized substance can be measured as a diameter when the microstructure is identified with an image analysis apparatus (Luzex) having a microscope, for example, and the cross-sectional area of each crystallized substance is converted into a circle.

  The reason for limiting the chemical components in the present invention will be described below.

Si coexists with Mg to form Mg ₂ Si-based precipitates and contributes to improving the strength of the final product. In order to further increase the strength of the final product after the aging treatment, Si is added in excess of the amount of Mg ₂ Si to be produced with respect to the amount of Mg described later, so the Si content is 0.95 mass. % Or more is desirable. On the other hand, when it exceeds 1.15 mass%, grain boundary precipitation of Si increases and grain boundary embrittlement is likely to occur, not only lowering the plastic workability of the ingot and the toughness of the final product, The average particle size of the crystallized product may exceed a predetermined upper limit. Therefore, the Si content is preferably in the range of 0.95% by mass to 1.15% by mass.
Mg coexists with Si to form Mg ₂ Si-based precipitates and contributes to improving the strength of the final product. If the Mg content is less than 0.8% by mass, the effect of precipitation strengthening may be reduced. On the other hand, when it exceeds 1.15% by mass, not only the plastic workability of the ingot and the toughness of the final product are deteriorated, but also the average particle size of the crystallized product of the ingot may exceed a predetermined upper limit. Therefore, the Mg content is preferably in the range of 0.8% by mass to 1.15% by mass.

Cu increases the apparent supersaturation amount of the Mg ₂ Si-based precipitates and increases the Mg ₂ Si precipitation amount, thereby significantly accelerating age hardening of the final product. If the Cu content exceeds 1.0% by mass, the forging processability of the ingot and the toughness of the final product may be reduced, and the corrosion resistance may be significantly reduced. Therefore, the Cu content needs to be in the range of 1.0 mass% or less.

  Mn crystallizes as an AlMnSi phase, and Mn that does not crystallize precipitates to suppress recrystallization. Due to the action of suppressing the recrystallization, the crystal grains are made fine even after the plastic working, and the effect of improving the toughness and corrosion resistance of the final product is brought about. If the Mn content is less than 0.4% by mass, the above effects may be reduced. On the other hand, if it exceeds 0.6% by mass, a huge intermetallic compound is formed, and the ingot structure of the present invention may not be satisfied. Therefore, the Mn content is preferably in the range of 0.4 mass% to 0.6 mass%.

  Cr also crystallizes as an AlCrSi phase, and Cr that does not crystallize precipitates and suppresses recrystallization. Due to the action of suppressing the recrystallization, the crystal grains are made fine even after the plastic working, and the effect of improving the toughness and corrosion resistance of the final product is brought about. If the Cr content is less than 0.1% by mass, the above-described effects may be reduced. On the other hand, if it exceeds 0.2% by mass, a giant intermetallic compound is formed, and the ingot structure of the present invention may not be satisfied. Therefore, the Cr content is preferably in the range of 0.11% by mass to 0.19% by mass.

  Fe is crystallized by combining with Al and Si in the alloy and prevents coarsening of crystal grains. If the Fe content is less than 0.2% by mass, the above effects may not be obtained. Moreover, when Fe exceeds 0.3 mass%, a coarse intermetallic compound will be produced | generated and there exists a possibility that plastic workability may deteriorate. Therefore, the Fe content is preferably 0.2% by mass to 0.3% by mass.

  Zn is treated as an impurity, and if it exceeds 0.25% by mass, the corrosion of aluminum itself is promoted and the corrosion resistance is deteriorated.

  Zr is treated as an impurity, and if it exceeds 0.05% by mass, the effect of refining crystal grains of the Al—Ti—B alloy is weakened, and the strength of the processed product after plastic working is reduced. % Or less is preferable.

  Ti is an alloy element that is effective in reducing the size of crystal grains, and prevents ingot cracking and the like from occurring in a continuous cast bar. If the Ti content is less than 0.012% by mass, the effect of miniaturization cannot be obtained. On the other hand, if the Ti content exceeds 0.035% by mass, coarse Ti compounds may crystallize and deteriorate toughness. . Therefore, the Ti content is preferably in the range of 0.012% by mass to 0.035% by mass.

  B, as well as Ti, is an element effective for refining crystal grains. If it is less than 0.0001% by mass, the effect cannot be obtained. On the other hand, if it exceeds 0.03% by mass, the toughness is deteriorated. There is a fear. Therefore, the B content is preferably in the range of 0.0001% by mass to 0.03% by mass.

  [Production Line] An example of the production line of the present invention will be described with reference to FIG.

  The production line includes an alloy melting furnace 31, a casting apparatus 32, a homogenization processing furnace 33, a raw material preheating apparatus 34, a forging apparatus 35, a machining apparatus 36, a solution treatment furnace 37, a quenching apparatus 38, an aging treatment furnace 39, The pickling device 40 includes a shot blasting device 41, a final machining device 42, and an inspection device 43.

  The alloy melting furnace 31 adjusts the alloy composition and keeps the molten alloy at a predetermined temperature. A melting and holding furnace and a molten metal cleaning device may be provided.

  The casting device 32 is a device that solidifies the molten alloy to obtain an ingot. The solidification rate can be adjusted by adjusting the cooling capacity such as the cooling water temperature and the cooling water amount.

  The homogenization furnace 33 is an apparatus that inserts an ingot into the furnace and applies the homogenization process to the ingot. The temperature can be controlled so that the inside of the furnace is in a predetermined temperature state.

  The ingot is processed into a material by an appropriate forming process such as extrusion, machining, and cutting.

  The material preheating device 34 is a device that heats a material to be molded in advance.

  The forging device 35 arranges an upper mold and a lower mold having molding holes, sets an ingot as a molding material in the molding holes, and performs plastic working by moving the mold up and down. If necessary, it is possible to have a lubricant spraying device for applying a lubricant to the molding hole of the mold and to apply a lubricant to the material.

  The machining device 36 is a device that performs machining such as cutting, drilling, and chamfering on a plastic molded product. May be omitted depending on product specifications.

  The solution treatment furnace 37 is a device that performs a solution treatment on a plastic-processed molded product. The temperature can be controlled so that the inside of the furnace is in a predetermined temperature state.

  The quenching device 38 is a device for rapidly cooling a molded product in a high temperature state. The molded product is put into water controlled to a certain temperature range and rapidly cooled.

  The aging treatment furnace 39 is an apparatus that performs an aging treatment, and performs an aging treatment such that the increment X is in a range of 0 <X ≦ 1 (IACS%) with reference to the conductivity at the peak aging time point. The temperature can be controlled so that the inside of the furnace is in a predetermined temperature state. Details will be described later.

  The pickling device 40 is a device for cleaning the molded product with an acid solution. May be omitted depending on product specifications.

  The shot blasting device 41 is a device that performs shot blasting on the surface of a molded product. May be omitted depending on product specifications.

  The final machining device 42 is a device that performs machining such as cutting, drilling, and chamfering in order to make a molded product into a final shape. Or it is an apparatus which makes a shape of a final part by combining or joining a molded product and another member. May be omitted depending on product specifications.

  The inspection device 43 is a device that performs an appearance inspection and, if necessary, a weight inspection. In some cases, it can be a direct visual inspection by a human.

  It is preferable that the apparatuses are connected by a conveying apparatus such as a conveyor or a conveyance vehicle.

  FIG. 4 is a block diagram showing an example of an aging furnace. The aging treatment furnace 39 includes a heating furnace 5 and a control unit 6. The heating furnace 5 further includes a temperature detector 51 and a heating device 52, and the control unit 6 includes an input unit 61, a data unit 62, a temperature monitoring unit 63, a temperature control unit 64, and a time control unit 65.

  In the data part 62, the increment X is 0 <X ≦ 1 (IACS%) based on the conductivity at the peak aging point in the aging treatment, which is measured in advance corresponding to the molded product to be processed. Enter a combination of time and temperature.

  The temperature monitoring unit 63 monitors the temperature in the furnace, compares the temperature with the temperature set in the data unit 62, outputs the result to the temperature control unit 64, and keeps the temperature in a predetermined state.

  The time control unit 65 monitors the aging processing time, compares it with the time set in the data unit 62, outputs the result to the temperature control unit 64, and sets the holding time to a predetermined state.

  Via the input unit 61, data input to the data unit 62 and start input of processing are performed. The input unit 61 can be an interface for remote operation from the central management system.

  Using the aging furnace 39 configured as described above, an aging treatment in which the increment X of the ingot conductivity is in the range of 0 <X ≦ 1 (IACS%) with reference to the conductivity at the peak aging point in the aging treatment. Can be implemented.

  Furthermore, by using the increase in conductivity as a key, a database of many combinations of temperature and holding time that can be realized, or by creating a database for each molding type and storing it in the data section 62, the operation status, product Even when the specifications and alloy specifications are changed, an appropriate aging treatment can be quickly selected and set.

  FIG. 5 is a block diagram showing another example of an aging furnace. This aging treatment furnace 39 </ b> A includes a heating furnace 50 and a control unit 60, similarly to the aging treatment furnace 39 described above. The heating furnace 50 further includes a temperature detector 510, a heating device 520, and a conductivity detector 530. The control unit 60 includes an input unit 610, a data unit 620, a temperature monitoring unit 630, a temperature control unit 640, a time control unit 650, A calculation unit 660 and a conductivity measurement unit 670 are provided.

  The conductivity measuring unit 670 monitors the output signal from the conductivity detector 530 that measures the conductivity of the surface of the processed product, and transfers it to the computing unit 660.

  The temperature monitoring unit 630 monitors the temperature in the furnace with an output signal from the temperature detector 510, compares the temperature with the temperature set in the data unit 620, outputs the result to the temperature control unit 640, and sets the temperature to a predetermined value. Keep in state.

  The time control unit 650 compares the aging processing time with the peak aging time input to the data unit 620 and notifies the calculation unit 660 of the timing of the peak aging time.

  The calculation unit 660 starts monitoring the conductivity increment X from the peak aging timing, and the increment X is 0 <X ≦ 1IACS% with reference to the conductivity at the peak aging point in the aging treatment. In the range where the increment X is 0 <X ≦ 1IACS% when the control signal is output to the temperature control unit 640 and the time control unit 650 at the time point before or beyond the range. End the aging process.

  Via the input unit 610, data input to the data unit 620, start input of aging processing, and the like are performed. The input unit 610 can be an interface for remote operation from the central management system.

  Using the aging furnace 39A having the above-described configuration, an aging treatment in which the increment of the ingot conductivity is in a range of 0 <X ≦ 1 (IACS%) with respect to the peak aging point in the aging treatment. Can be implemented. By doing in this way, the increment of the electrical conductivity of the ingot during heat treatment can be directly monitored, and a reliable aging treatment can be performed by feeding back the monitoring result to the heat treatment conditions.

  Further, by combining the time and temperature combination that is the peak aging point in the aging treatment measured in advance and storing it in the data unit 620 in correspondence with the molded article to be processed, the operation status, product specification, and the like are stored. Even when the alloy specifications are changed, it is possible to quickly select and set an appropriate scheduled aging treatment.

  Another operation example of the aging furnace 39A of FIG. 5 will be described. The conductivity measuring unit 670 monitors the output signal from the conductivity detector 530 that measures the conductivity of the surface of the processed product, and transfers it to the computing unit 660. In the data portion 620, the lower limit value of the differential value of the conductivity that changes with the aging treatment temperature and the aging treatment time is input corresponding to the molded product to be aging treated. This conductivity differential value is for determining the peak aging point. A preferable aging treatment time is input.

  The temperature monitoring unit 630 monitors the temperature in the furnace, compares the temperature with the temperature set in the data unit 620, outputs the result to the temperature control unit 640, and maintains the temperature in a predetermined state.

  The time control unit 650 compares the aging processing time with a preferable aging processing time input to the data unit 620 and informs the calculation unit 660 of the comparison result.

  The calculation unit 660 starts monitoring the conductivity increment X from the start of the aging process, compares the differential value with the determination value of the data unit 620, first determines the peak aging time point in the aging process, and determines the time point. As a reference, it is monitored whether or not the conductivity increment X is 0 <X ≦ 1 (IACS%), and the temperature control unit 640 and the time control unit 650 are inspected when exceeding the range or before that time. A control signal is output, and the aging process is terminated in a range where the increment X is 0 <X ≦ 1 (IACS%).

  By doing in this way, the aging treatment is performed in which the increment of the ingot conductivity is set in the range of 0 <X ≦ 1 (IACS%) with respect to the peak aging point in the aging treatment. Can do. In addition, it is possible to directly monitor the increment of the ingot conductivity during the heat treatment, and to feed back the monitoring result to the heat treatment conditions, so that a reliable aging treatment can be performed. For example, even if there is a case where the state of change in conductivity is different from that expected due to variations in the molded product, stable aging treatment can be performed reliably.

  Furthermore, when the change state is different than expected (for example, when it is expected that the process is not finished within a preferable processing time range), the processing quality can be stabilized by increasing or decreasing the temperature. .

  Although the aging furnace is shown as a batch process, it can be a continuous tunnel furnace instead of a batch process. In this case, since the necessary processing time can be controlled by changing the temperature while monitoring the conductivity so that the passage time in the tunnel is in a certain range, the processing amount per time of the production line is stabilized, and Processing quality can also be stabilized.

  The aluminum alloy plastic workpiece manufactured by the production line according to the present invention has an increase in the ingot conductivity, and the increment X is 0 <X ≦ 1 (IACS%) with reference to the peak aging point in the aging treatment. Therefore, it becomes an aluminum alloy plastic processed product having high strength and excellent corrosion resistance.

  For example, examples of plastic processed products made of aluminum alloy include automobile parts, motorcycle parts, ship parts, aircraft parts, trains, and freight vehicle parts as structural materials for vehicles and transportation equipment.

  For example, automotive parts made of aluminum alloy plastic products include upper arms, lower arms, knuckles, control arms, lower links, subframes, compression rods, transverse links, and the like.

  In addition, these parts can be manufactured as a whole by using the aluminum alloy plastic processed product of the present invention, but the aluminum alloy plastic processed product of the present invention and other members are combined or joined to manufacture as a part. In other words, an aluminum alloy plastic processed product may be used as a part of the part.

  (Example) Next, the Example of this invention is described.

  Aluminum alloy ingots having the chemical composition shown in Table 1 were cast by a hot top casting method under conditions of a casting temperature of 750 ± 50 ° C. and a casting speed of 240 ± 50 mm / min. The ingot was homogenized at 470 ° C. for 6 hours. The obtained ingot was heated to 530 ° C., and plastic working was performed on the shape of a suspension arm part of an automobile as shown in FIG. 6 by hot forging. The plastic working rate was calculated to be 50%. Next, the plastic processed product was subjected to a solution treatment at 530 ° C. for 4 hours, water-quenched at 60 ° C., and then subjected to an aging treatment.

  As shown in Table 2, the aging treatment was carried out at a temperature of 180 ° C. for 2 to 15 hours and as shown in Table 3 at a temperature of 200 ° C. for 0.5 to 12 hours.

  And the test piece was extract | collected from the suspension arm components shown in FIG. 6 which is an aluminum alloy plastic processing product of the chemical composition of the alloy A of Table 1, and hardness, electrical conductivity, and tensile strength were measured. The electrical conductivity was measured according to JIS-H0505 using Metal Condux 2010 (manufactured by Electronic Measurement Industry). The conductivity is an average value obtained by measuring five points in a state in which a test piece is collected from part A in FIG. The hardness is an average value obtained by measuring in accordance with JIS-Z2245, collecting a test piece from part A in FIG. The tensile strength is an average value measured in accordance with JIS-Z2241, taking a JIS14A proportional test piece (see JIS-Z2201) from part B of FIG.

Further, a C-ring No. 2 test piece (see JIS-H8711) was taken from part A of FIG. 6 and a stress corrosion cracking test (SCC test) was performed. The test conditions were as follows: a test solution containing CrO ₃ : 36 g / l, K ₂ Cr ₂ O ₇ : 30 g / l, NaCl: 3 g / l heated to 95 ° C. and 95% C-ring test piece. The test piece was immersed for 10 hours in a state where proof stress was applied, and the presence or absence of occurrence of stress corrosion cracking in the test piece was confirmed. As a result, it was confirmed that stress corrosion cracking did not occur under all conditions and there was no problem. Moreover, about the corrosion weight loss, the cross section of each test piece was observed with the optical microscope, and it evaluated by the average value which measured the product of the depth and the width | variety of the generated pitting corrosion 30 pieces.

  Tables 2 and 3 evaluate the corrosion resistance and strength of the aluminum plastic processed product after the aging treatment. Corrosion resistance was evaluated by the product of the width and depth of pitting corrosion as corrosion weight loss. The strength was calculated by calculating the strength ratio [(strength / maximum strength) × 100 (%)] with the maximum strength, and evaluating the strength reduction due to the overaging treatment.

The definitions of symbols in the evaluation column are as follows.
×: Corrosion amount is large and corrosion resistance is poor ◎: Corrosion amount is small and corrosion resistance is good, and strength ratio is 95% or more ○: Corrosion amount is small and corrosion resistance is good, and strength ratio is less than 95% to 90% or more Small amount, good corrosion resistance, and strength ratio is less than 90%

  From Comparative Examples 1 to 3 and Tables 1 to 7 in Table 2 and Comparative Examples 6 and 7 and Examples 8 to 14 in Table 3, the conductivity increment X based on the conductivity at the time of peak aging is 0. In the range exceeding, the product of pitting depth and width (corrosion weight loss) decreases rapidly, and it can be confirmed that the corrosion resistance is improved by preventing the corrosion amount from increasing.

  From Comparative Example 5 in Table 2 and Examples 1 to 7 and Comparative Example 8 and Examples 8 to 14 in Table 3, the strength ratio is 90% when the conductivity increment X is in the range of 0 <X ≦ 1IACS%. In addition, when the conductivity increment X is in the range of 0 <X ≦ 0.7IACS%, the strength ratio is 95% or more, which is a preferable range because there is little decrease in strength due to overaging treatment. When the increment X of conductivity exceeds 1, the strength ratio becomes less than 90%, and the strength is significantly reduced. Therefore, in order to prevent strength reduction due to overaging treatment and maintain strength characteristics, the conductivity increment X based on the conductivity at the time of peak aging is in the range of 0 <X ≦ 1IACS%, preferably 0 < It can be seen that it is necessary to define the range of X ≦ 0.7 IACS%.

  Table 4 evaluates the amount of Cu added. For plastic processed products of three types of aluminum alloy ingots with different Cu addition amounts shown in Table 1, the aging is within the range of 0 <X ≦ 1IACS% in the conductivity increment X based on the conductivity at the peak aging time point. It has been processed. In Comparative Example 9 in which the added amount of Cu is 1% by mass or more, the corrosion weight loss is large and the corrosion resistance is remarkably deteriorated. Moreover, in Example 3 and Example 15 in which the Cu addition amount is 1% by mass or less, the corrosion weight loss is suppressed and the corrosion resistance is improved. This shows that it is necessary to make Cu addition amount 1 mass% or less.

  As described above, according to the present invention, in an aluminum alloy plastic processed product manufactured from an ingot of an Al—Mg—Si based aluminum alloy, Cu is contained in an amount of 1% by mass or less, and the conductivity is at the time of peak aging. Since it has an increment of greater than 0 and less than 1 IACS% with respect to the electrical conductivity of Al, the corrosion weight loss is greatly increased even for plastic processed products of Al-Mg-Si alloys with increased Cu addition. It is possible to suppress the corrosion resistance and improve the corrosion resistance as well as increasing the strength. Therefore, even if the part is thinned, the weight can be reliably reduced by suppressing the corrosion weight loss, and the use of the Al-Mg-Si alloy plastic work product for transportation equipment can be further expanded. It becomes like this.

It is a figure which shows the relationship between the aging treatment time when the aging treatment is performed at 200 ° C. on the plastically processed product of the Al—Mg—Si alloy. It is a figure which shows the relationship between the aging treatment time and the hardness at the time of performing an aging treatment at 200 degreeC on the plastic processed goods of an Al-Mg-Si type alloy. It is a schematic explanatory drawing of an example of the manufacturing line of this invention. It is a block diagram which shows an example of an aging treatment furnace. It is a block diagram which shows the other example of an aging treatment furnace. It is a figure which shows the external appearance of the suspension component of a motor vehicle. It is a figure which shows the relationship between the electrical conductivity of the Al alloy forging material surface, and intensity | strength.

Explanation of symbols

DESCRIPTION OF SYMBOLS 5 Heating furnace 6 Control part 31 Alloy melting furnace 32 Casting apparatus 33 Homogenization processing furnace 34 Material preheating apparatus 35 Forging apparatus 36 Machining apparatus 37 Solution treatment furnace 38 Quenching apparatus 39 Aging furnace 39A Aging furnace 40 Pickling apparatus DESCRIPTION OF SYMBOLS 41 Shot blasting apparatus 42 Final machining apparatus 43 Inspection apparatus 50 Heating furnace 51 Temperature detector 52 Heating apparatus 60 Control part 61 Input part 62 Data part 63 Temperature monitoring part 64 Temperature control part 65 Time control part 510 Temperature detector 520 Heating apparatus 530 Conductivity detector 610 Input unit 620 Data unit 630 Temperature monitoring unit 640 Temperature control unit 650 Time control unit 660 Operation unit 670 Conductivity measurement unit

Claims (15)

In an aluminum alloy plastic work product manufactured from an ingot of an Al-Mg-Si-based aluminum alloy,
Cu is contained in an amount of 1% by mass or less, and the conductivity has an increment of greater than 0 and less than or equal to 1 IACS% with respect to the conductivity at the time of peak aging.
This is an aluminum alloy plastic processed product.   The aluminum alloy plastic work product according to claim 1, wherein the conductivity has an increment of greater than 0 and less than or equal to 0.7 IACS% with respect to the conductivity at the time of peak aging.   While containing 1 mass% or less of Cu, Mg is 0.8 to 1.15 mass%, Si is 0.95 to 1.15 mass%, Mn is 0.4 to 0.6 mass%, and Fe is 0.00. 2 to 0.3 mass%, Cr 0.11 to 0.19 mass%, Zn 0.25 mass% or less, Zr 0.05 mass% or less, Ti 0.012 to 0.035 mass%, The aluminum alloy plastic processed product according to claim 1 or 2, wherein B is contained in an amount of 0.0001 to 0.03% by mass or less, and the remainder is made of Al and inevitable impurities.   The aluminum alloy plastic work product according to any one of claims 1 to 3, which is obtained by controlling an aging treatment time after a peak aging time in an artificial age hardening treatment.   The peak aging time point is an elapsed time point of aging treatment time required for the hardness to increase and reach a peak according to the aging treatment time during the artificial age hardening treatment, according to any one of claims 1 to 4. Aluminum alloy plastic processed product.   The aluminum alloy plastic processed product according to any one of claims 1 to 4, wherein the peak aging point is a point at which the hardness becomes maximum with the aging time x temperature as a horizontal axis.   The aluminum alloy according to any one of claims 1 to 4, wherein the peak aging time point is a time point when the electrical conductivity has increased in accordance with the aging treatment time and started to show a constant value during the artificial age hardening treatment. Plastic processed product.   The aluminum alloy plastic processed product according to any one of claims 1 to 7, which is an automotive part. In the manufacturing method of an aluminum alloy plastic work product for manufacturing an aluminum alloy plastic work product from an ingot of an Al-Mg-Si based aluminum alloy,
Melting and casting an aluminum alloy with Cu of 1% by mass or less,
Homogenization treatment and plastic working are performed on the casting obtained by the above melting casting,
The plastic processed product obtained by the plastic processing is subjected to solution treatment, water quenching treatment and artificial age hardening treatment,
The aging treatment time after the peak aging time in the artificial age hardening treatment is controlled so that the electrical conductivity of the plastic processed product has an increment of greater than 0 and less than 1 IACS% with respect to the electrical conductivity at the peak aging time. To
A method for producing an aluminum alloy plastic processed product.   The method for producing an aluminum alloy plastic processed product according to claim 9, wherein the artificial age hardening treatment has an aging treatment temperature of 170 ° C to 210 ° C and an aging treatment time of 0.5 hours to 18 hours.   The method for producing an aluminum alloy plastic processed product according to claim 9 or 10, wherein the solution treatment is performed at a temperature of 530 ° C or higher and 560 ° C or lower, and the water quenching is performed at a temperature of 70 ° C or lower.   The method for producing an aluminum alloy plastic processed product according to any one of claims 9 to 11, wherein the plastic processing is one type or a combination of two or more types selected from extrusion processing, forging processing, and rolling processing.   The automotive part obtained using the manufacturing method of the aluminum alloy plastic fabrication goods of any one of Claim 9 to 12. In an aging treatment furnace used for artificial age hardening when producing an aluminum alloy plastic work product from an ingot of an Al-Mg-Si-based aluminum alloy,
Control the aging treatment time after the peak aging time in the artificial age hardening treatment so that the electrical conductivity of the plastic product made of aluminum alloy has an increment of greater than 0 and less than 1 IACS% with respect to the conductivity at the peak aging time. To
An aging furnace characterized by that.   The manufacturing system of the aluminum alloy plastic processed goods which has an aging treatment furnace of Claim 14.

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