CN111801433A - Hollow extrusion material of Al-Mg-Si series aluminum alloy and method for producing the same - Google Patents
Hollow extrusion material of Al-Mg-Si series aluminum alloy and method for producing the same Download PDFInfo
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- CN111801433A CN111801433A CN201980016556.0A CN201980016556A CN111801433A CN 111801433 A CN111801433 A CN 111801433A CN 201980016556 A CN201980016556 A CN 201980016556A CN 111801433 A CN111801433 A CN 111801433A
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21C—MANUFACTURE OF METAL SHEETS, WIRE, RODS, TUBES OR PROFILES, OTHERWISE THAN BY ROLLING; AUXILIARY OPERATIONS USED IN CONNECTION WITH METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL
- B21C23/00—Extruding metal; Impact extrusion
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- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
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- C22C21/00—Alloys based on aluminium
- C22C21/02—Alloys based on aluminium with silicon as the next major constituent
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- C22C21/06—Alloys based on aluminium with magnesium as the next major constituent
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- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22F—CHANGING THE PHYSICAL STRUCTURE OF NON-FERROUS METALS AND NON-FERROUS ALLOYS
- C22F1/00—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working
- C22F1/04—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working of aluminium or alloys based thereon
- C22F1/05—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working of aluminium or alloys based thereon of alloys of the Al-Si-Mg type, i.e. containing silicon and magnesium in approximately equal proportions
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- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22F—CHANGING THE PHYSICAL STRUCTURE OF NON-FERROUS METALS AND NON-FERROUS ALLOYS
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Abstract
Provided is a high-strength Al-Mg-Si alloy hollow extrusion material having excellent bending crush resistance and corrosion resistance. The aluminum alloy hollow extruded material is formed into the following structure, containing: si: 0.80 to 1.25 mass%, Mg: 0.65 to 1.20 mass%, Fe: 0.15 to 0.30 mass%, Mn: 0.40 to 0.80 mass%, Cu: 0.01 to 0.60 mass%, Cr: 0.09-0.21 mass%, Ti: 0.01 to 0.10 mass%, a Zr content of 0.05 mass% or less, and the balance being Al and unavoidable impurities, wherein when the Si content in the alloy is α (mass%), and the Mg content in the alloy is β (mass%), two relational expressions of 0.90. gtoreq. (. beta./1.73). gtoreq.0.19 and 1.90. gtoreq. + (. beta./1.73). gtoreq.1.00 are satisfied, the metal structure of the cross section of the extrusion material has a fibrous structure, the ratio of the fibrous structure to the entire area of the cross section is 80% or more, the 0.2% yield strength of the hollow extrusion material is 330MPa or more, and the ultimate bend R of the extrusion material is 5mm or less.
Description
Technical Field
The present invention relates to an Al-Mg-Si-based high-strength aluminum alloy hollow extruded material having excellent bending crush resistance and corrosion resistance, and a method for producing the same.
In the scope of the present specification and claims, the term "section of the hollow extruded material parallel to the extrusion direction" means a section parallel to the extrusion direction (section of the thick pipe wall portion) at a position avoiding such a rib, when the cross-sectional shape of the hollow extruded material is provided with a rib in the hollow space, for example, a shape like a japanese letter, a chinese character tian (refer to fig. 3 and 4), and the like. For example, when the cross-sectional shape of the hollow extruded material is a rectangular shape (see fig. 3 and 4), the cross-sectional shape is a section taken along line II-II in fig. 4.
Background
Since Al — Mg — Si-based (6000-based) aluminum alloys are practical alloys in terms of corrosion resistance and recyclability while having strength, they are used as structural materials for transportation equipment such as vehicles, ships, automobiles, and motorcycles, which are required to have high strength and corrosion resistance.
In particular, a6061 is used in many cases in Al — Mg — Si-based (6000-based) aluminum alloys, but in order to improve transportation efficiency by reducing the weight of a vehicle body structure, further reduction in weight is required, and therefore, it is required to achieve high strength as a material. In order to achieve such high strength, improvements such as changing the kind of the added metal of the aluminum alloy and the content thereof have been studied.
As an Al — Mg — Si based (6000 based) aluminum alloy extrusion material used for transportation equipment such as automobiles, materials described in patent documents 1 and 2 can be cited. Patent document 1 proposes a method of realizing a high strength of 350MPa or more in yield strength by adopting a structure in which the area ratio of a fibrous structure in a cross section parallel to the hot extrusion direction is 95% or more. Patent document 2 proposes an aluminum alloy extrusion material having a structure in which the structure in the cross section of the extrusion material in the thickness direction is mainly fibrous and the thickness of the recrystallized structure in the surface layer portion is 500 μm or less on one side, thereby achieving a 0.2% proof stress of 270 to 330 MPa.
Documents of the prior art
Patent document 1: japanese patent No. 6022882
Patent document 2: japanese patent No. 5473718
Disclosure of Invention
However, as a drawback that may occur due to the high strength of the aluminum alloy extruded material used as a structural material of the transportation equipment, toughness of the material is lowered and the crush resistance is lowered. Even in the structural material of a transportation machine, particularly in the material of an automobile frame, if the toughness of the aluminum alloy material itself is insufficient, the impact at the time of collision cannot be sufficiently absorbed, and there is a fear that the vehicle body is seriously damaged.
As an index for evaluating toughness of a hollow extruded material as an impact absorbing member (energy absorbing member), bending crush characteristics can be mentioned. In the bending test defined in JIS Z2248, the smaller the limit bending R value (mm) at which no crack occurs, the more the load loss due to the crack at the time of impact is eliminated, and the higher the energy can be absorbed, so the performance evaluation as an impact absorbing member is higher.
The aluminum alloy extruded material described in patent document 1 realizes a high strength of 350MPa or more in yield strength, but it is not disclosed about the buckling and crushing characteristics required as an impact absorbing member, and it is not available from patent document 1 as to what kind of structure is required to sufficiently improve the performance as an impact absorbing member.
Further, the aluminum alloy extruded material described in patent document 2 is controlled to have a fibrous structure mainly by adding Mn and Zr, and although high strength and crush resistance are improved, since the yield strength is in the range of 270 to 330MPa, the strength is lower than that of an iron-based material generally used for a frame material, and therefore, if it is intended to ensure the strength and rigidity equivalent to those of an iron-based material, there is a problem that weight reduction is difficult to achieve. In the example of patent document 2, when the yield strength is 350MPa or more, the limit bending R value is 10mm, and thus, in the technique of patent document 2, if high strength is to be achieved, the bending crush resistance is greatly reduced, and sufficient performance as an impact absorbing member cannot be obtained.
The present invention has been made in view of the above-mentioned background, and an object thereof is to provide an Al — Mg — Si aluminum alloy hollow extruded material having excellent bending crush resistance and corrosion resistance and high strength, and a method for producing the same.
In order to achieve the above object, the present invention provides the following means.
[1] An Al-Mg-Si series aluminum alloy hollow extrusion material is characterized by comprising:
si: 0.80 to 1.25 mass%, Mg: 0.65 to 1.20 mass%, Fe: 0.15 to 0.30 mass%, Mn: 0.40 to 0.80 mass%, Cu: 0.01 to 0.60 mass%, Cr: 0.09-0.21 mass%, Ti: 0.01 to 0.10 mass%, and a Zr content of 0.05 mass% or less, the balance being Al and unavoidable impurities,
when the Si content in the aluminum alloy is "α" (mass%), and the Mg content in the aluminum alloy is "β" (mass%), the following formulas (1) and (2) are satisfied:
0.90 ≥ alpha- (beta/1.73) ≥ 0.19 formula (1)
1.90 ≥ beta + (beta/1.73) ≥ 1.00 formula (2)
In a cross section parallel to the extrusion direction of the aluminum alloy hollow extruded material, a metal structure has a fibrous structure, and the proportion of the area of the fibrous structure in the entire area of the cross section is 80% or more,
the 0.2% yield strength of the aluminum alloy hollow extrusion material is more than 330MPa,
the aluminum alloy hollow extruded material has a limit bending R of 5.0mm or less as measured in a bending test according to JIS Z2248-2006.
[2] A method for producing an Al-Mg-Si aluminum alloy hollow extrusion material, characterized by comprising:
a melt forming step of obtaining an aluminum alloy melt containing: si: 0.80 to 1.25 mass%, Mg: 0.65 to 1.20 mass%, Fe: 0.15 to 0.30 mass%, Mn: 0.40 to 0.80 mass%, Cu: 0.01 to 0.60 mass%, Cr: 0.09-0.21 mass%, Ti: 0.01 to 0.10 mass%, and a Zr content of 0.05 mass% or less, with the balance being Al and unavoidable impurities;
a casting step of obtaining a billet by casting the obtained melt;
a homogenization heat treatment step of maintaining the billet at 480 to 530 ℃ for 2 to 15 hours to perform homogenization heat treatment;
a cooling step of cooling the homogenized blank to 200 ℃ or lower at an average cooling rate of 150 ℃/hr or higher;
an extrusion step of subjecting the billet subjected to the cooling step to hot extrusion at an extrusion speed of 5 to 15 m/min at 500 to 560 ℃ to obtain a hollow extruded material;
a quenching step of quenching the obtained hollow extrusion material from a state of 500-570 ℃ to 150 ℃ or less at a cooling rate of 10-500 ℃/sec; and
an aging treatment step of heating the hollow extrusion material subjected to the quenching step at a temperature of 150 to 210 ℃ for 1 to 24 hours,
the aluminum alloy forming the melt satisfies the following formulas (1) and (2) when the content of Si in the aluminum alloy is "α" (mass%) and the content of Mg in the aluminum alloy is "β" (mass%):
0.90 ≥ alpha- (beta/1.73) ≥ 0.19 formula (1)
1.90. gtoreq.beta. + (beta/1.73) or more than 1.00 formula (2).
[1] The invention of (1) can provide an Al-Mg-Si aluminum alloy hollow extrusion material having excellent bending and crushing resistance and corrosion resistance and high strength. Since the hollow extruded material has a limit bend R of 5.0mm or less, sufficient performance as an impact absorbing member can be ensured.
[2] In the invention (1), the Al-Mg-Si aluminum alloy hollow extrusion material according to the invention can be produced. That is, an Al-Mg-Si aluminum alloy hollow extrusion material having excellent bending crush resistance and corrosion resistance and high strength can be produced.
Drawings
FIG. 1 is a perspective view showing an example of an Al-Mg-Si aluminum alloy hollow extrusion material according to the present invention.
FIG. 2 is a perspective view showing a method of producing a test piece for bending test from a hollow extruded material.
FIG. 3 is a perspective view showing another example of the Al-Mg-Si aluminum alloy hollow extrusion material of the present invention.
Fig. 4 is a front view of the hollow extruded material of fig. 3.
FIG. 5 is a photograph of a metal structure of a longitudinal section (a longitudinal section cut parallel to an extrusion direction) of a hollow extruded material of Al-Mg-Si based aluminum alloy of example 21.
Detailed Description
The aluminum alloy hollow extrusion material of the present invention is characterized by containing: si: 0.80 to 1.25 mass%, Mg: 0.65 to 1.20 mass%, Fe: 0.15 to 0.30 mass%, Mn: 0.40 to 0.80 mass%, Cu: 0.01 to 0.60 mass%, Cr: 0.09-0.21 mass%, Ti: 0.01 to 0.10 mass%, the Zr content being 0.05 mass% or less, the balance being Al and unavoidable impurities, and satisfying the following formulas (1) and (2) when the Si content in the aluminum alloy is "α" (mass%), and the Mg content in the aluminum alloy is "β" (mass%):
0.90 ≥ alpha- (beta/1.73) ≥ 0.19 formula (1)
1.90 ≥ beta + (beta/1.73) ≥ 1.00 formula (2)
In a cross section parallel to an extrusion direction of the aluminum alloy hollow extruded material, a metal structure has a fibrous structure, and a proportion of an area of the fibrous structure in an entire area of the cross section is 80% or more, a 0.2% yield strength of the aluminum alloy hollow extruded material is 330MPa or more, and an ultimate bending R measured in a bending test performed according to JIS Z2248 (2006) is 5.0mm or less for the aluminum alloy hollow extruded material.
The aluminum alloy hollow extruded material of the above-described structure is excellent in bending crush resistance and corrosion resistance and has high strength, and therefore is suitable for use as a structural material (frame or the like) of a vehicle body of a vehicle such as an automobile, a railway or the like.
In the aluminum alloy hollow extruded material of the present invention, the above formula (1) and formula (2) need to be satisfied. Satisfying the above formulas (1) and (2) are components necessary for obtaining the Al — Mg — Si-based aluminum alloy hollow extruded material of the present invention which is excellent in bending crush resistance and corrosion resistance and has high strength. That is, when the value calculated by the formula "α - (. beta./. 1.73)" is less than 0.19, the strength-improving effect by the aging treatment is small, and a sufficiently high strength cannot be obtained. On the other hand, when the value calculated by the formula "α - (. beta./. 1.73)" exceeds 0.90, grain boundary precipitates are coarsened by Si, whereby the extrudability at the time of hot extrusion processing is deteriorated, appearance defects are generated in the hollow extruded material, the toughness of the hollow extruded material is lowered, and the bending crush resistance is insufficient. In addition, when the value calculated from the formula "β + (β/1.73)" is less than 1.00, Mg is included2The amount of Si-based precipitates is small, the strength-improving effect by aging treatment is small, and a sufficiently high strength cannot be obtained. On the other hand, when the value calculated from the formula "β + (β/1.73)" exceeds 1.90, Mg2The excessive Si-based precipitates deteriorate the extrudability during hot extrusion processing, cause appearance defects in the hollow extruded material, lower the toughness of the hollow extruded material, and lower the bending crush resistance. Among them, the composition preferably satisfies the relational expressions of 0.85. gtoreq. (. beta./1.73). gtoreq.0.24 and 1.82. gtoreq.beta. + (. beta./1.73). gtoreq.1.09. Moreover, the composition satisfies the relational expressions of 0.80. gtoreq. (. beta./1.73). gtoreq.0.29 and 1.74. gtoreq.beta. + (. beta./1.73). gtoreq.1.18 are particularly preferable.
The composition of the aluminum alloy (such as the meaning of the limitation of the content range of each component) will be summarized and described in detail in the following paragraphs that describe the production method of the present invention.
In the present invention, it is important that the metal structure has a fibrous structure in a cross section parallel to the extrusion direction of the aluminum alloy hollow extruded material 1, and the fibrous structure accounts for 80% or more of the entire area of the cross section. When the area ratio of the fibrous structure is 80% or more, a large 0.2% yield strength of 330MPa or more can be achieved, and good bending and crushing resistance can be obtained. FIG. 5 shows an example of a photograph of the metal structure of a longitudinal section (a longitudinal section parallel to the extrusion direction) of the aluminum alloy hollow extruded material of the present invention. The fibrous structure is a structure in which fibrous structures are not recrystallized but remain due to pressing. In fig. 5, in the photograph of the metal structure of the longitudinal section of the hollow extruded material, the surface layer portion on the outer side and the surface layer portion on the inner side of the tube wall become "recrystallized structures", and the core portion other than these surface layer portions become "fibrous structures". Wherein the ratio of the area of the fibrous structure to the entire area of the cross section is preferably 85% or more.
The 0.2% yield strength of the aluminum alloy hollow extrusion material is more than 330 MPa. Such high strength can be achieved by having the above-described specific metal composition and satisfying the above-described formulae (1) and (2) and the like. Such high strength is comparable to that of iron-based materials generally used for frames in strength, and is excellent in bending and crushing resistance. Wherein the 0.2% yield strength of the aluminum alloy hollow extruded material is preferably 350MPa or more.
The aluminum alloy hollow extruded material of the present invention has a limit bending R of 5.0mm or less as measured in a bending test according to JIS Z2248-2006. By having the above-described specific structure, excellent bending crush resistance can be achieved with a limit bend R of 5.0mm or less. Wherein the aluminum alloy hollow extruded material preferably has a limit bend R of 4.0mm or less.
Fig. 1 shows an embodiment of an aluminum alloy hollow extruded material 1 according to the present invention. The aluminum alloy hollow extrusion material 1 shown in fig. 1 has a so-called square tube shape having a rectangular outer shape in cross section, but is not particularly limited to such a shape. The cross-sectional shape of the hollow extruded material 1 is not particularly limited, but a cross-sectional shape that can reduce the weight of a vehicle structural member and can secure sufficient rigidity and strength as a structural material is preferably employed, and specifically, examples of the cross-sectional shape include a square shape (see fig. 1), a japanese-letter shape, a field-letter shape (see fig. 3 and 4), a hollow cross-sectional shape such as a circular shape, an oval shape, and the like. The hollow extrusion material 1 is preferably designed in such a size that the diameter of a circumscribed circle of the cross-sectional shape is in the range of 15 to 570 mm. The wall thickness T of the hollow extrusion material 1 is preferably set in the range of 2 to 10 mm. The thickness T is 2mm or more, whereby deformation due to the influence of thermal shrinkage during forced cooling after extrusion can be prevented, and the weight saving can be ensured by the thickness T being 10mm or less.
Next, a method for producing the aluminum alloy hollow extruded material 1 of the present invention will be described. The manufacturing method comprises a melt forming step of obtaining an aluminum alloy melt, and a casting step of obtaining a billet by casting the aluminum alloy melt, wherein the aluminum alloy melt contains: si: 0.80 to 1.25 mass%, Mg: 0.65 to 1.20 mass%, Fe: 0.15 to 0.30 mass%, Mn: 0.40 to 0.80 mass%, Cu: 0.01 to 0.60 mass%, Cr: 0.09-0.21 mass%, Ti: 0.01 to 0.10 mass%, and a Zr content of 0.05 mass% or less, with the balance being Al and unavoidable impurities.
(melt formation step)
In the melt forming step, an aluminum alloy melt is obtained which is melt-prepared to have a composition containing: si: 0.80 to 1.25 mass%, Mg: 0.65 to 1.20 mass%, Fe: 0.15 to 0.30 mass%, Mn: 0.40 to 0.80 mass%, Cu: 0.01 to 0.60 mass%, Cr: 0.09-0.21 mass%, Ti: 0.01 to 0.10 mass%, and a Zr content of 0.05 mass% or less, with the balance being Al and unavoidable impurities. In the case where the content of Si in the alloy is "α" (mass%) and the content of Mg in the aluminum alloy is "β" (mass%), the aluminum alloy melt should satisfy the following formulas (1) and (2):
0.90 ≥ alpha- (beta/1.73) ≥ 0.19 formula (1)
1.90. gtoreq.beta. + (beta/1.73) or more than 1.00 formula (2).
Among them, the composition preferably satisfies the relational expressions of 0.85. gtoreq. (. beta./1.73). gtoreq.0.24 and 1.82. gtoreq.beta. + (. beta./1.73). gtoreq.1.09. Moreover, the composition satisfies the relational expressions of 0.80. gtoreq. (. beta./1.73). gtoreq.0.29 and 1.74. gtoreq.beta. + (. beta./1.73). gtoreq.1.18 are particularly preferable.
(casting step)
Next, the obtained melt is cast to obtain a casting material (casting step). The casting method is not particularly limited as long as a conventionally known method is employed, and examples thereof include a continuous casting rolling method, a hot-top casting method, a float-pressure casting method, a semi-continuous casting method (DC casting method), and the like. In this casting step, it is preferable to reduce the crystal grain size of the microstructure and the crystal formed in the ingot (charge) by performing casting at a high cooling rate.
The following steps are performed in this order, namely, a homogenization heat treatment step, a cooling step, an extrusion step, a quenching step, and an aging treatment step.
(homogenization Heat treatment Process)
The obtained billet was subjected to a homogenization heat treatment. Namely, the billet is subjected to a homogenization heat treatment by holding the billet at 480 to 530 ℃ for 2 to 15 hours. When the temperature is lower than 480 ℃, the softening of the ingot blank is insufficient, the pressure during hot extrusion is significantly increased, the appearance quality is deteriorated, and the productivity is also deteriorated. On the other hand, when the temperature exceeds 530 ℃, precipitates of Mn and Cr are coarsened, whereby the effect of suppressing recrystallization is reduced, and the toughness of the hollow extruded material 1 is reduced due to the occurrence of recrystallization, and it is difficult to obtain high strength. Wherein the temperature of the homogenization heat treatment is preferably 485 to 525 ℃.
When the time for the homogenization heat treatment is less than 2 hours, the softening of the ingot is insufficient, the pressure during the hot extrusion processing is significantly increased, the appearance quality is deteriorated, and the productivity is also deteriorated. When the time is less than 2 hours, segregation in the grain in the ingot structure disappears and the effect of homogenization becomes insufficient, and the toughness of the hollow extruded material 1 decreases, and it is difficult to obtain high strength. On the other hand, if the time of the homogenization heat treatment exceeds 15 hours, a better effect by the homogenization heat treatment is not obtained, and productivity is rather lowered.
(Cooling Process)
Subsequently, the homogenized blank is cooled to a temperature of 200 ℃ or lower at an average cooling rate of 150 ℃/hour or higher. The average cooling rate is more preferably large. The cooling method in this cooling step is not particularly limited, and examples thereof include fan cooling and spray cooling. The reason why the ingot is forcibly cooled at an average cooling rate of 150 ℃/hr or more in this way is to suppress the growth of coarse precipitates of the solid solution elements in the cooling process after the homogenization heat treatment. By suppressing the coarse growth, the strength of the hollow extruded material can be sufficiently improved by the aging treatment thereafter, and the toughness of the hollow extruded material can be sufficiently ensured, and sufficient bending and crushing resistance can be obtained.
(extrusion Process)
And (3) performing hot extrusion processing on the blank subjected to the cooling step at an extrusion speed of 5-15 m/min under the condition of setting the temperature to be 500-560 ℃ to obtain the hollow extruded material. When the heating temperature is less than 500 ℃, the elements added to the ingot are not dissolved in the matrix and remain, and thus the strength cannot be improved by the aging treatment. On the other hand, when the heating temperature exceeds 560 ℃, eutectic melting (overburning) may occur locally in the hollow extruded material due to heat generation in the process after the extrusion process. Therefore, the heating temperature during the hot extrusion is set to 500 to 560 ℃. The heating temperature during the hot extrusion processing is preferably set to 510 to 550 ℃. The heating time of the billet is not particularly limited, but is set to a time that can ensure good productivity in consideration of the heating device being provided on the line of the extrusion process, and is preferably set to 30 minutes or less, and particularly preferably set to 15 minutes or less.
The extrusion speed during the hot extrusion is set to 5 to 15 m/min. In view of productivity, the extrusion speed is as high as possible, but when the extrusion speed exceeds 15 m/min, peeling and/or cracks may occur on the surface of the hollow extruded material. On the other hand, when the extrusion speed is less than 5 m/min, the productivity is lowered.
(quenching step)
The temperature of the hollow extrusion material after the hot extrusion processing needs to be 500-570 ℃. The temperature of the hollow extruded material immediately after the ejection from the die was measured with a non-contact thermometer or a contact thermometer. When the measurement temperature is less than 500 ℃, the elements added to the ingot are not dissolved in the matrix and remain, and thus the strength cannot be improved by the aging treatment. In the case where the measurement temperature exceeds 570 ℃, eutectic melting (overburning) may locally occur in the hollow extruded material. Wherein the temperature of the hollow extrusion material after the hot extrusion processing is preferably 510-560 ℃.
Rapidly cooling the hollow extrusion material having a temperature of 500-570 ℃ immediately after the hot extrusion processing to 150 ℃ or lower at a cooling rate of 10-500 ℃/sec. Such quenching may be performed, for example, using a cooling device provided on the extrusion outlet side. The rapid cooling under such conditions is an important step in forming a metal structure in which the metal structure of the hollow extruded material has a fibrous structure and the fibrous structure accounts for 80% or more of the entire area of the cross section of the hollow extruded material. In this quenching step, when the cooling rate is less than 10 ℃/sec, quenching during cooling becomes insufficient, the toughness of the hollow extruded material decreases, and it is difficult to obtain high strength. On the other hand, when the cooling rate exceeds 500 ℃/sec, deformation due to thermal shrinkage difference occurs in thick portions and thin portions, and dimensional accuracy is deteriorated.
The cooling method in the quenching step is not particularly limited, and examples thereof include fan air cooling, spray cooling, shower cooling, liquid nitrogen cooling, and water cooling. Further, the quenching may be carried out by appropriately combining the cooling methods exemplified above.
In the quenching step, the cooling rate of the hollow extruded material is preferably set to 50 to 500 ℃/sec, and particularly preferably set to 100 to 500 ℃/sec.
(aging treatment Process)
And then heating the hollow extrusion material subjected to the quenching step at a temperature of 150-210 ℃ for 1-24 hours to perform aging treatment. When the aging treatment temperature is lower than 150 ℃, precipitates become too fine, and the aging hardening is insufficient, so that a high-strength hollow extruded material cannot be obtained. On the other hand, when the aging temperature exceeds 210 ℃, the precipitation is coarsened by overaging treatment, and a high-strength hollow extruded material cannot be obtained. When the aging treatment time is less than 1 hour, the hollow extruded material is subjected to a sub-aging treatment, and thus a high-strength hollow extruded material cannot be obtained. When the aging treatment time exceeds 24 hours, the hollow extruded material becomes overaged and high strength cannot be obtained. Wherein the aging treatment temperature is preferably set to 160 to 200 ℃. The aging treatment time is preferably set to 1 to 16 hours.
In the above-described production method of the present invention, if the solutionizing treatment and/or the quenching treatment is performed after the extrusion step, the formed fibrous structure is damaged, and therefore, it is not desirable to perform such a solutionizing treatment and quenching treatment.
In the above-described manufacturing method of the present invention, for example, for application to a vehicle body structural material (frame or the like) of a vehicle such as an automobile, a railway, or the like, one or two or more kinds of processing such as drawing, cutting, bending, grinding, welding, mechanical fastening, or the like may be performed after the extrusion step as necessary.
Next, the composition of the "aluminum alloy" in the aluminum alloy hollow extruded material of the present invention and the method for producing the aluminum alloy hollow extruded material of the present invention will be described in detail below. The aluminum alloy is a silicon-containing alloy comprising: 0.80 to 1.25 mass%, Mg: 0.65 to 1.20 mass%, Fe: 0.15 to 0.30 mass%, Mn: 0.40 to 0.80 mass%, Cu: 0.01 to 0.60 mass%, Cr: 0.09-0.21 mass%, Ti: 0.01 to 0.10 mass%, and the Zr content is 0.05 mass% or less, with the balance being Al and unavoidable impurities.
The Si coexists with Mg to form Mg2The Si-based precipitates contribute to the improvement of the strength of the hollow extruded material 1. As described above, Si generates Mg by exceeding the content relative to Mg2Since the strength improvement by aging treatment can be sufficiently achieved by adding an excessive amount of Si, the Si content is set to 0.80 mass%The above. On the other hand, when the Si content exceeds 1.25 mass%, grain boundary precipitation of Si increases, toughness of the hollow extruded material decreases, and extrudability during hot extrusion processing deteriorates. Therefore, the Si content is set to 0.80 to 1.25 mass%. Among them, the Si content is preferably 0.95 to 1.20% by mass, more preferably 1.02 to 1.17% by mass.
The Mg coexists with Si to form Mg2The Si-based precipitates contribute to the improvement of the strength of the hollow extruded material 1. When the Mg content is less than 0.65 mass%, the precipitation strengthening effect cannot be sufficiently obtained, and high strength cannot be ensured. On the other hand, when the Mg content exceeds 1.20 mass%, Mg2The Si-based precipitates excessively increase to thereby lower the toughness of the hollow extruded material, and the extrusion pressure at the time of hot extrusion processing significantly increases to thereby lower the appearance quality and/or lower the productivity. Therefore, the Mg content is set to 0.65 to 1.20 mass%. Among them, the Mg content is preferably set to 0.75 to 1.15 mass%, more preferably 0.85 to 1.10 mass%.
The Fe has an effect of acting as an AlFeSi phase crystal, thereby preventing the grain from being coarsened. When the Fe content is less than 0.15 mass%, the effect of preventing the coarsening of crystal grains cannot be sufficiently obtained. On the other hand, if the Fe content exceeds 0.30 mass%, coarse intermetallic compounds are formed, the toughness of the hollow extruded material is reduced, and appearance defects called skinning may occur during hot extrusion processing. Therefore, the Fe content is set to 0.15 to 0.30 mass%. Among them, the Fe content is preferably set to 0.15 to 0.25 mass%.
The Mn crystallizes as an AlMnSi phase, and the non-crystallized Mn precipitates to suppress recrystallization. By suppressing the action of this recrystallization, the structure after the hot extrusion processing can be organized into a fibrous structure, whereby high strength can be achieved. If the Mn content is less than 0.40 mass%, the above-mentioned recrystallization inhibiting effect is not obtained, and the recrystallized structure grows coarse, whereby the strength is reduced (high strength cannot be ensured), and the structure control becomes difficult, and a structure state in which a fibrous structure and a recrystallized structure are mixed is obtained, and the toughness is reduced. On the other hand, when the Mn content exceeds 0.80%, coarse intermetallic compounds are generated, and the toughness of the hollow extruded material is lowered. Therefore, the Mn content is set to 0.40 to 0.80 mass%. Among them, the Mn content is preferably set to 0.40 to 0.70 mass%, more preferably 0.40 to 0.60 mass%. Further, Mn can synergistically enhance the above-described effects by being added in combination with Cr having the same effects.
The Cu is added with Mg2The apparent supersaturation amount of Si precipitates increases Mg2Si is precipitated, thereby remarkably promoting age hardening of the hollow extruded material of the final product. If the Cu content is less than 0.01 mass%, age hardening cannot be sufficiently obtained. On the other hand, if the Cu content exceeds 0.60 mass%, the toughness of the hollow extruded material is lowered, and the extrudability at the time of hot extrusion is deteriorated. In addition, an excessive increase in the amount of addition may reduce corrosion resistance, increase susceptibility to grain boundary corrosion, and cause stress corrosion cracking. Therefore, the Cu content is set to 0.01 to 0.60 mass%. Among them, the Cu content is preferably set to 0.10 to 0.50 mass%, more preferably 0.30 to 0.50 mass%.
The Cr is crystallized as an AlCrSi phase, and the non-crystallized Cr has an effect of precipitating to suppress recrystallization. By suppressing the action of this recrystallization, the structure after the hot extrusion processing can be organized into a fibrous structure, whereby high strength can be achieved. If the Cr content is less than 0.09 mass%, the above-mentioned recrystallization-inhibiting effect is not obtained, and the recrystallized structure coarsens and grows, whereby the strength decreases (high strength cannot be ensured), and the structure control becomes difficult, and a structure state in which a fibrous structure and a recrystallized structure are mixed is obtained, and the toughness decreases. On the other hand, if the Cr content exceeds 0.21 mass%, coarse intermetallic compounds are formed, and the toughness of the hollow extruded material is lowered. Therefore, the Cr content is set to 0.09 to 0.21 mass%. Among them, the Cr content is preferably set to 0.11 to 0.19 mass%. Further, the effect can be synergistically enhanced by adding Cr in combination with Mn having the same effect.
The Ti is an element effective in achieving grain refinement and prevents ingot cracks from occurring in the cast rod (billet). If the Ti content is less than 0.01% by mass, the above-mentioned effects may not be obtained. On the other hand, if the Ti content exceeds 0.10%, coarse Ti compounds are crystallized to lower the toughness of the hollow extruded material. Therefore, the Ti content is set to 0.01 to 0.10 mass%. When B (boron) which is relatively easy to be mixed in when Ti is contained is included, the Ti content is preferably set in the range of 0.0001 to 0.03 mass%.
The above-mentioned Zr is an element having an effect of suppressing recrystallization, similarly to Mn and Cr, but the content of Zr is set to 0.05 mass% or less. If the Zr content exceeds 0.05 mass%, the above-mentioned effect of refining Ti crystal grains is inhibited and the toughness of the hollow extruded material is lowered. Therefore, the Zr content is set to 0.05 mass% or less. Zr may not be contained (the Zr content may be 0 mass%). The Zr content is preferably set to 0.01 mass% or less (including 0 mass%; i.e., including no Zr).
Examples
Next, specific examples of the present invention will be described, but the present invention is not particularly limited to these examples.
< example 1>
Will contain: si: 0.95 mass%, Fe: 0.20 mass%, Cu: 0.40 mass%, Mn: 0.50 mass%, Mg: 0.65 mass%, Cr: 0.15 mass%, Zr: 0.01 mass%, Ti: 0.02 mass%, Al: an aluminum alloy (alloy No. a in table 1) containing 97.12 mass% and inevitable impurities was heated to obtain an aluminum alloy melt, and an ingot blank having a diameter of 156mm and a length of 450mm was produced by a hot top casting method using the aluminum alloy melt.
Next, the ingot was subjected to a homogenization heat treatment at 500 ℃ for 7 hours (homogenization heat treatment step; see production condition No.1 in Table 2). The ingot blank after the homogenization heat treatment step was forcibly cooled at an ingot cooling rate of 200 ℃/hour until the ingot temperature reached 200 ℃ or lower (cooling step; see production condition No.1 in table 2). Then, the ingot blank having undergone the cooling step was subjected to hot extrusion at an ingot heating temperature of 530 ℃ and an extrusion speed of 10 m/min, thereby obtaining a hollow extruded material (see FIGS. 1 and 2) having a square tube shape of 45mm in length and 45mm in width, a corner R of 1.5mm, and a tube wall thickness (wall thickness) T of 2.5mm (extrusion step; see production condition No.1 in Table 2). Then, the 540 ℃ hollow extruded material obtained by the hot extrusion (the temperature of the hollow extruded material at the exit of the extrusion die was measured by a contact thermometer) was rapidly cooled to a temperature of 150 ℃ or less at a cooling rate of 400 ℃/sec (rapid cooling step; see production condition No.1 in Table 2). The hollow extruded material having undergone the quenching step was cut into a length of 400mm, and then heated at 180 ℃ for 6 hours to be subjected to aging treatment (aging treatment step; see production condition No.1 in Table 2). Thus, an Al-Mg-Si aluminum alloy hollow extruded material 1 shown in FIG. 1 was obtained.
< example 2>
An Al — Mg — Si aluminum alloy hollow extruded material 1 shown in fig. 1 was obtained in the same manner as in example 1 (the same production conditions as in example 1 were employed for production conditions No.1) except that an aluminum alloy melt of alloy No. b shown in table 3 was used as the aluminum alloy melt. The composition of the aluminum alloy of alloy No. b is shown in table 1.
< examples 3 to 19 and comparative examples 1 to 14>
An Al — Mg — Si aluminum alloy hollow extruded material 1 shown in fig. 1 was obtained in the same manner as in example 1 (the same production conditions as in example 1 were adopted) except that a melt of an aluminum alloy of each alloy No. shown in table 3 (the composition of an aluminum alloy of each alloy No. is shown in table 1) was used as the aluminum alloy melt.
< example 20>
An Al — Mg — Si aluminum alloy hollow extruded material 1 shown in fig. 1 was obtained in the same manner as in example 1, except that an aluminum alloy melt of alloy No. g shown in table 4 was used as the aluminum alloy melt, and production condition No.2 (see table 2) was used as the production condition. The composition of the aluminum alloy of alloy No. g is shown in table 1.
< examples 21 to 29 and comparative examples 15 to 24>
An Al — Mg — Si aluminum alloy hollow extruded material 1 shown in fig. 1 was obtained in the same manner as in example 20 (using an aluminum alloy melt of alloy No. g) except that the production conditions of the respective production condition nos. shown in table 4 were adopted as the production conditions (the production conditions of the respective production condition nos. are shown in table 2).
In each of examples and comparative examples, the cooling rate of the extrudate in the quenching step was adjusted by selecting an optimum cooling method from various cooling methods such as cooling by air, fan air cooling, spray air cooling, shower air cooling, liquid nitrogen cooling, and water cooling.
For each of the aluminum alloy hollow extruded materials obtained as described above, the "ratio of the fibrous structure area to the entire area of the cross section of the hollow extruded material" was measured by the following measurement method, and various evaluations were performed based on the following evaluation methods.
< method for measuring the ratio of the area of fibrous texture to the entire cross-sectional area of hollow extruded Material >
For the hollow extruded material, after a cross section (cross section of the Z-Z line in fig. 1) parallel to the extrusion direction in the direction of the hollow extruded material was cut, the cross section (cut cross section) of the hollow extruded material was mirror-polished, followed by electrolytic etching, and then the cross section (cut surface) was observed with an optical microscope. Fig. 5 shows a photograph of a metal structure using an optical microscope of a cross section (cut surface) of the aluminum alloy hollow extruded material of example 21. The microstructure photograph of fig. 5 is an optical microscope photograph taken with a field of view set at an arbitrary magnification in a region including the wall thickness (T ═ 2.5mm) of the entire hollow extruded material. As shown in fig. 5, a fibrous structure (fibrous structure) extending substantially parallel to the extrusion direction was observed inside, and a recrystallized structure (a surface layer structure different in color tone and morphology from the fibrous structure) was observed in the surface layer portions on both the upper and lower sides of the fibrous structure (see fig. 5).
In the photographs of the metal structure using an optical microscope of the cross section (cut surface) of each hollow extrusion material, the ratio of the area of the fibrous structure to the entire area of the cross section was determined by image analysis in a plurality of visual fields, and the case where the ratio was 80% or more was determined as the "fibrous structure" (see tables 3 and 4), the case where the ratio was 20% or more and less than 80% (the case where the structure other than the fibrous structure was the recrystallized structure) was determined as the "mixed structure", and the case where the ratio was less than 20% (the case where the structure other than the fibrous structure was the recrystallized structure) was determined as the "recrystallized structure" (see tables 3 and 4).
< 0.2% yield Strength measurement >
A tensile test was conducted at room temperature (25 ℃ C.) in accordance with JIS Z2241-2011, whereby the 0.2% yield strength (MPa) was measured. That is, as shown in FIG. 2, a test piece 10 of JIS5 was prepared from the obtained hollow extruded material 1 by the method described in JIS Z2201-1998. The test piece 10 according to JIS5 has a parallel portion width (W) of 25mm, a parallel portion length (L) of 60mm, and a thickness (T) of 2.5mm (see FIG. 2). In addition, the distance between the dots was set to 50mm in the test piece. The test piece was subjected to a tensile test in the pressing direction of the test piece (a part of the hollow pressed material) using an instron type tensile tester. The tensile test speed was set to 2 mm/min, and the yield strength was set to 10 mm/min after the measurement. The number n of test pieces No. JIS5 was 3, and the average value of the 3 test pieces was "0.2% yield strength" (see tables 3 and 4). In tables 3 and 4, the case where the 0.2% yield strength was 350MPa or more was marked as "excellent", the case where the 0.2% yield strength was 330MPa or more and less than 350MPa was marked as "o", and the case where the 0.2% yield strength was less than 330MPa was marked as "x".
< method for evaluating appearance of extruded Material >
The surface of the obtained aluminum alloy hollow extruded material was visually observed to examine the presence or absence of peeling of the surface of the extruded material and the presence or absence of cracks at the corners, and the appearance quality of the hollow extruded material was evaluated based on the following criteria.
(determination criteria)
". O" … did not peel, nor did there be corner cracks
Either or both of peeling and corner cracking occurred in the case of "x" ….
< method of evaluating Corrosion resistance >
A test piece of 4mm in length (width 4mm) × length (length in the extrusion direction) 45mm × thickness 2.5mm was obtained from the center position in the width direction of the obtained aluminum alloy hollow extruded material in one direction in the width direction, and 2 test pieces of 4mm in length (width 4mm) × length (length in the extrusion direction) 45mm × thickness 2.5mm were obtained from the center position in the width direction in the other direction in the width direction (n ═ 2).
Corrosion resistance test liquid (CrO) with liquid temperature set to 90 DEG C3Has a concentration of 36g/L, K2Cr2O730g/L, NaCl, 3 g/L) for 10 hours. At this time, the top surfaces of the 2 test pieces were immersed in the corrosion resistance test solution for 10 hours in a state of being loaded with a yield strength of 90% from the upper side. After 10 hours of immersion, 2 test pieces were taken out, and the presence or absence of stress corrosion cracking was visually confirmed or, when the presence or absence of stress corrosion cracking was not visually confirmed, the cross-sectional area was observed by an optical microscope to evaluate the corrosion resistance of the hollow extruded material based on the following criteria.
(criteria for determination)
Both of the "O" … 2 test pieces produced no stress corrosion cracking.
At least one of the "X" … 2 test pieces confirmed the occurrence of stress corrosion cracking.
< method of evaluating bendability (bending test method) >
The 180 DEG bending test was carried out according to JIS Z2248-2006 by the press bending method. That is, as shown in FIG. 2, a JIS3 test piece 10 was prepared from the obtained hollow extruded material 1. The test piece 10 of JIS3 was set to have a width (W) of 30mm, a length (L) of 200mm, and a thickness (T) of 2.5mm (see FIG. 2). For the test piece (a part of the hollow extruded material), a 180 ° bending test was performed using an oil pressure universal tester. In the bending test, a bending line was set as an extrusion direction (of the hollow extruded material), a limit bending R (minimum inside radius R) (mm) in which a crack caused breakage does not occur at a portion outside a bending R portion was measured, and the bendability was evaluated based on the following criteria.
(determination criteria)
"excellent" … ultimate bending R value is below 3.0mm
"O" … ultimate bending R value exceeds 3.0mm and is 5.0mm or less
"Delta" … ultimate bend R values were over 5.0mm and below 5.5mm
The "x" … ultimate bending R value is 5.5mm or more.
< comprehensive evaluation >
Among 4 evaluation items of "0.2% yield strength", "appearance of extruded material", "corrosion resistance", "bendability (bending crush resistance)", an evaluation result having "x" in 1 or more items was "failed", and an evaluation result having no "x" in all of the 4 evaluation items was "passed".
As is clear from the table, the Al-Mg-Si aluminum alloy hollow extrusion materials of examples 1 to 29 of the present invention had good appearance quality, high strength, excellent corrosion resistance and excellent bending and crushing resistance, and the 0.2% yield strength was 330MPa or more.
In contrast, in comparative examples 1 to 14, the aluminum alloy compositions deviated from the specified range of the present invention, and therefore, the comprehensive evaluation was not satisfactory. Specifically, in comparative examples 1 and 2, the content of Si is less than the predetermined range of the present invention, and therefore the 0.2% yield strength is insufficient. In comparative example 3, since the Si content is larger than the range defined in the present invention, the numerical value of "α - (. beta./. 1.73)" is also larger than the range defined in the present invention, and the extruded material is inferior in appearance and bendability. In comparative example 4, the Cu content is larger than the predetermined range of the present invention, and therefore the appearance and bendability of the extrudate are poor. In comparative example 5, since the Mg content is larger than the range defined in the present invention, the numerical value of "β + (β/1.73)" is also larger than the range defined in the present invention, and the appearance and bendability of the extrudate are poor. In comparative example 6, the Cr content was less than the predetermined range of the present invention, and the Zr content was more than the predetermined range of the present invention, so the bendability was poor. In comparative example 7, the Mn content is less than the predetermined range of the present invention, and the Zr content is greater than the predetermined range of the present invention, so the bendability is poor. In comparative example 8, the Mn content is greater than the predetermined range of the present invention, and hence the bendability is poor. In comparative example 9, since the Mg content is less than the range defined in the present invention, the value of "β + (β/1.73)" is also less than the range defined in the present invention, and the 0.2% yield strength is insufficient. In comparative example 10, since the Si content is less than the range defined in the present invention, the value of "α - (. beta./. 1.73)" is also less than the range defined in the present invention, and the 0.2% yield strength is insufficient. In comparative example 11, since the content of Fe is larger than the predetermined range of the present invention, the appearance of the extrusion material is poor, and since the content of Mn is smaller than the predetermined range of the present invention, the metal structure form becomes a mixed structure form, and the bendability is poor. In comparative example 12, since the Mn content is less than the predetermined range of the present invention, the metal structure form is a recrystallized structure form, and the numerical value of "α - (. beta./. 1.73)" is less than the predetermined range of the present invention, the 0.2% yield strength is insufficient. In comparative example 13, since the Mn content and the Cr content are less than the predetermined ranges of the present invention, the metal structure form is a recrystallized structure form, and the Si content and the Mg content are less than the predetermined ranges of the present invention, the numerical value of "β + (β/1.73)" is also less than the predetermined ranges of the present invention, and therefore the 0.2% yield strength is insufficient. In comparative example 14, the Ti content was higher than the range defined in the present invention, and therefore the bendability was poor (see table 3).
In comparative examples 15 to 24, the aluminum alloy compositions in the production method of the present invention were within the predetermined ranges, but the other production conditions were outside the predetermined ranges of the production method of the present invention, and therefore the comprehensive evaluation was not satisfactory. Specifically, in comparative example 15, since the homogenization heat treatment temperature was less than the range defined in the present invention, hot extrusion processability was deteriorated, and the appearance and bendability of the extruded material were poor. In comparative example 16, since the homogenization heat treatment temperature is higher than the predetermined range of the present invention, the recrystallization-suppressing effect is small, the metal structure form is a mixed structure form, and the bendability is poor. In comparative example 17, since the homogenization heat treatment time was less than the range specified in the present invention, softening of the ingot was not sufficiently performed, and the hot extrusion workability was deteriorated, and peeling, cracks, and the like were generated, and the appearance of the extruded material was poor. In comparative example 18, the ingot heating temperature in the extrusion step was lower than the predetermined range of the present invention, and the temperature of the hollow extruded material at the start of rapid cooling in the rapid cooling step was lower than the predetermined range of the present invention, so that hot extrusion workability was deteriorated, peeling, cracks, and the like were generated, and the appearance of the extruded material was poor. In comparative example 19, since the ingot heating temperature in the extrusion step was higher than the predetermined range of the present invention, and the temperature of the hollow extruded material at the start of rapid cooling in the rapid cooling step was higher than the predetermined range of the present invention, it is presumed that eutectic melting (overburning) locally occurred in the hollow extruded material, peeling, cracks, and the like occurred, the extruded material appearance was poor, and the bendability was also deteriorated due to the decrease in toughness. In comparative example 20, the extrusion speed in the extrusion step was higher than the predetermined range of the present invention, the amount of work heat generated during extrusion was excessively large, and the temperature of the hollow extruded material at the start of rapid cooling in the subsequent rapid cooling step was higher than the predetermined range of the present invention, and it was estimated that eutectic melting (overburning) locally occurred in the hollow extruded material, peeling and cracks occurred, and the extruded material appearance was poor, and the bendability was also poor due to the decrease in toughness. In comparative example 21, since the cooling rate of the hollow extruded material in the quenching step was less than the range defined in the present invention, the precipitates coarsened during the quenching, and therefore the 0.2% yield strength was insufficient and the bendability was also poor. In comparative example 22, the 0.2% yield strength was insufficient because the aging treatment temperature was lower than the range defined in the present invention. In comparative example 22, the aging treatment time is longer than the range defined in the present invention, and therefore, the aging treatment may be excessive to further lower the 0.2% proof stress. In comparative example 23, the aging treatment temperature was higher than the range defined in the present invention, and therefore the 0.2% yield strength was insufficient. In comparative example 23, the aging treatment time was shorter than the range defined in the present invention, and therefore, it is considered that the aging treatment was insufficient and the 0.2% proof stress was further reduced. In comparative example 24, since the cooling rate of the ingot in the cooling step was lower than the range defined in the present invention, it was not possible to suppress the coarse growth of precipitates in the cooling process after the homogenization heat treatment, and the bendability was poor (see table 4).
Industrial applicability
The Al-Mg-Si-based aluminum alloy hollow extrusion material of the present invention and the Al-Mg-Si-based aluminum alloy hollow extrusion material obtained by the production method of the present invention are excellent in bending crush resistance and corrosion resistance and have high strength, are comparable in strength to conventional iron-based materials, and are excellent in bending crush resistance, and therefore are suitable for use as an alternative material to conventional iron-based materials. For example, when used as a structural material (frame or the like) of a vehicle body of a transportation machine such as a vehicle, a ship, an automobile, or a motorcycle, the vehicle body can be reduced in weight.
The present application is accompanied by the priority claim of japanese patent application No. 2018-38157 filed on 3/5/2018, the disclosure of which constitutes a part of the present application as such.
The terms and descriptions used herein are used for the purpose of describing embodiments of the present invention, and the present invention is not limited thereto. The present invention allows various design changes within the scope of the claims without departing from the spirit thereof.
Description of the reference numerals
1 … aluminum alloy hollow extrusion material
Claims (2)
1. An Al-Mg-Si series aluminum alloy hollow extrusion material is characterized by comprising:
si: 0.80 to 1.25 mass%, Mg: 0.65 to 1.20 mass%, Fe: 0.15 to 0.30 mass%, Mn: 0.40 to 0.80 mass%, Cu: 0.01 to 0.60 mass%, Cr: 0.09-0.21 mass%, Ti: 0.01 to 0.10 mass%, and a Zr content of 0.05 mass% or less, the balance being Al and unavoidable impurities,
when the Si content in the aluminum alloy is defined as "α" by mass and the Mg content in the aluminum alloy is defined as "β" by mass, the following formulas (1) and (2) are satisfied:
0.90 ≥ alpha- (beta/1.73) ≥ 0.19 formula (1)
1.90 ≥ beta + (beta/1.73) ≥ 1.00 formula (2)
In a cross section parallel to the extrusion direction of the aluminum alloy hollow extruded material, a metal structure has a fibrous structure, and the proportion of the area of the fibrous structure in the entire area of the cross section is 80% or more,
the 0.2% yield strength of the aluminum alloy hollow extrusion material is more than 330MPa,
the aluminum alloy hollow extruded material has a limit bending R of 5.0mm or less as measured in a bending test according to JIS Z2248-2006.
2. A method for producing an Al-Mg-Si aluminum alloy hollow extrusion material, characterized by comprising:
a melt forming step of obtaining an aluminum alloy melt containing: si: 0.80 to 1.25 mass%, Mg: 0.65 to 1.20 mass%, Fe: 0.15 to 0.30 mass%, Mn: 0.40 to 0.80 mass%, Cu: 0.01 to 0.60 mass%, Cr: 0.09-0.21 mass%, Ti: 0.01 to 0.10 mass%, and a Zr content of 0.05 mass% or less, with the balance being Al and unavoidable impurities;
a casting step of obtaining a billet by casting the obtained melt;
a homogenization heat treatment step of maintaining the billet at 480 to 530 ℃ for 2 to 15 hours to perform homogenization heat treatment;
a cooling step of cooling the homogenized blank to 200 ℃ or lower at an average cooling rate of 150 ℃/hr or higher;
an extrusion step of subjecting the billet subjected to the cooling step to hot extrusion at an extrusion speed of 5 to 15 m/min at 500 to 560 ℃ to obtain a hollow extruded material;
a quenching step of quenching the obtained hollow extrusion material from a state of 500-570 ℃ to 150 ℃ or less at a cooling rate of 10-500 ℃/sec; and
an aging treatment step of heating the hollow extrusion material subjected to the quenching step at a temperature of 150 to 210 ℃ for 1 to 24 hours,
the aluminum alloy forming the melt satisfies the following formulas (1) and (2) when the content of Si in the aluminum alloy is defined as "α" mass% and the content of Mg in the aluminum alloy is defined as "β" mass%:
0.90 ≥ alpha- (beta/1.73) ≥ 0.19 formula (1)
1.90. gtoreq.beta. + (beta/1.73) or more than 1.00 formula (2).
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| JP2018038157 | 2018-03-05 | ||
| JP2018-038157 | 2018-03-05 | ||
| PCT/JP2019/002688 WO2019171818A1 (en) | 2018-03-05 | 2019-01-28 | Al-Mg-Si-BASED ALUMINUM ALLOY HOLLOW EXTRUDED MATERIAL AND METHOD FOR PRODUCING SAME |
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| JP7182425B2 (en) * | 2018-10-22 | 2022-12-02 | 昭和電工株式会社 | Al-Mg-Si-based aluminum alloy extruded material and method for producing the same |
| WO2020117771A1 (en) * | 2018-12-03 | 2020-06-11 | Rio Tinto Alcan International Limited | Aluminum extrusion alloy |
| JP2023061742A (en) * | 2021-10-20 | 2023-05-02 | 株式会社Uacj | Extrusion multiple hole pipe and method for manufacturing the same |
| JP7341266B2 (en) * | 2022-02-10 | 2023-09-08 | 株式会社神戸製鋼所 | Bumper reinforcement material and its manufacturing method |
| CN117070787B (en) * | 2023-10-12 | 2024-01-19 | 中铝科学技术研究院有限公司 | Aluminum alloy profile, preparation method and application thereof |
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| JP2019151918A (en) | 2019-09-12 |
| JP7215920B2 (en) | 2023-01-31 |
| WO2019171818A1 (en) | 2019-09-12 |
| CN111801433B (en) | 2021-11-09 |
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