JP6638192B2 - Aluminum alloy processing material and method of manufacturing the same - Google Patents

Description

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

  The aluminum alloy is an alloy containing aluminum as a main component. Aluminum (Al) is a relatively light metal, but high-purity aluminum is very soft, so Cu (copper), Mn (manganese), Si (silicon), Mg (magnesium), Zn (zinc), Ni ( By alloying with an additive such as nickel), desired properties such as strength, toughness, and ductility can be improved.

  Among aluminum alloys, the so-called 7000-series Al-Zn-Mg-Cu alloy is a high strength alloy, and is utilized in various fields by making use of the lightness and strength of the aluminum alloy.

  Patent Literature 1 discloses an aircraft product made of an aluminum alloy for the purpose of obtaining a good balance between toughness and static mechanical properties. The technique disclosed in this document discloses adjusting the concentration of an additive element and the like for the purpose of obtaining a good balance of toughness, static mechanical properties, corrosion resistance, and elongation at break. Patent Literature 1 discloses that toughness is improved by satisfying a condition such as Mg / Cu <2.4 as an additive element of an aluminum alloy.

Japanese Patent No. 4535731

However, depending on the field to which the aluminum alloy is applied, a product having higher strength may be required. For example, a product that is lightweight and has high impact resistance may be required.
Therefore, an object of the present invention is to provide a high-strength aluminum alloy processed material and a method for manufacturing the same.

According to the present invention, Zn: 9% to 11% by mass, Mg: 2.0% to less than 2.8% by mass, Cu: more than 0.8% by mass to 1.2% by mass, Zr 0.08% by mass or less and 0.25% by mass or less; Cr; 0.02% by mass or more and 0.30% by mass or less;
The balance consists of Al and unavoidable impurities, the content of Mg and Cu satisfies the relationship of Mg / Cu ≧ 2.5, and the total content of Zr and Cr is 0.12% by mass or more and 0.42% or more. An aluminum alloy processed material, which is not more than mass% and has a plastic working structure.

  According to one embodiment of the present invention, the processed aluminum alloy material further contains Mn; 0.05 mass% or more and 0.32 mass% or less, and the total content of Zr, Cr, and Mn is 0. It is not less than 12% by mass and not more than 0.42% by mass.

  Further, according to the present invention, Zn: 9 mass% to 11 mass%, Mg: 2.00 to less than 2.80 mass%, Cu: more than 0.8 mass% to 1.2 mass%, Zr; 0.08% by mass or more and 0.25% by mass or less, Cr; containing 0.02% by mass or more and 0.30% by mass or less, and the balance consists of Al and inevitable impurities. The relationship of Mg / Cu ≧ 2.5 is satisfied, and the total content of Zr and Cr is 0.12% by mass or more and 0.42% by mass or less, plastic working, solution treatment, quenching treatment and aging treatment Are provided sequentially, and a method for producing a processed aluminum alloy material is provided.

  According to one embodiment of the present invention, the method for producing a processed aluminum alloy material further includes Mn; 0.05 mass% or more and 0.32 mass% or less, and the total content of Zr, Cr, and Mn is reduced. , 0.12% by mass or more and 0.42% by mass or less.

  According to one aspect of the present invention, in the above-described method for manufacturing a processed aluminum alloy material, as the plastic working, an extrusion ratio is 5 to 100, and an ingot temperature is 300 to 450 ° C., and hot extrusion is performed. C., a quenching treatment for cooling the range of 450 ° C. to 100 ° C. at a cooling rate of 1000 ° C./min or more, and an aging treatment for 10 hours to 30 hours at 100 ° C. to 180 ° C. Features.

  Hereinafter, embodiments of the present invention will be described.

<Aluminum alloy processed material>
One embodiment of the present invention is Zn: 9% by mass or more and 11% by mass or less, Mg: 2.0% by mass or more and less than 2.8% by mass, Cu: more than 0.8% by mass and 1.2% by mass or less. , Zr: 0.08% by mass or more and 0.25% by mass or less, Cr: 0.02% by mass or more and 0.30% by mass or less, with the balance being Al and inevitable impurities, containing Mg and Cu. The amount satisfies the relationship of Mg / Cu ≧ 2.5, the sum of the contents of Zr and Cr is 0.12% by mass or more and 0.42% by mass or less, and has a plastic working structure. Aluminum alloy processed material. The aluminum alloy processed material of the present embodiment is a high-strength aluminum alloy processed material.

(Zn, Mg, Cu)
The processed aluminum alloy material of the present embodiment has a Zn (zinc) content of 9% by mass or more and 11% by mass or less.

  The aluminum alloy processed material of the present embodiment has a Mg (magnesium) content of 2.0% by mass to 2.8% by mass. More preferably, the content of Mg is 2.2 mass% or more and 2.8 mass% or less.

  The aluminum alloy processed material of the present embodiment has a Cu (copper) content of more than 0.8% by mass and not more than 1.2% by mass.

An aluminum alloy containing the above elements, by aging treatment after solution treatment, Zn and Mg to form Zn-Mg-based precipitates (compounds such as MgZn _2). Mg and Cu form Al-Cu-Mg-based precipitates (compounds such as Al ₂ CuMg). Precipitation strengthening by these precipitates contributes to the strength of the aluminum alloy.

If the content of the above elements is less than 9% by mass of Zn, less than 2.0% by mass of Mg, and 0.8% by mass or less of Cu, precipitation strengthening cannot be sufficiently performed outside the lower limit range, and the aluminum alloy has Less than desired strength.
When the content of the above elements is more than 11% by mass of Zn, more than 2.8% by mass of Mg, and more than 1.2% by mass of Cu, a crystallized substance formed at the time of casting becomes coarse and homogeneous. A solid solution cannot be sufficiently formed by the solution treatment or the solution treatment, and the concentration of stress on the crystallized material remaining after the heat treatment becomes a starting point of fracture, thereby reducing the elongation of the aluminum alloy.

As described above, Zn, Mg, and Cu are elements that contribute to the strength, but it has been confirmed that strengthening by a Zn—Mg-based precipitate increases the strength of the Al alloy most.
However, regarding the alloy components, it is necessary to consider the contribution of castability and strength per amount of addition. Zn has a high density, and when added excessively, it lowers the specific strength. Therefore, the amount of Zn is preferably 11% by mass or less from the viewpoint of castability and specific strength.

The content of Mg and Cu is preferably 3.2% by mass ≦ Mg + Cu ≦ 4.2% by mass.
When the content of Mg + Cu is less than 3.2% by mass, the amount of the Mg-Cu-based precipitate is insufficient. If the content of Mg + Cu exceeds 4.2% by mass, coarse crystals are formed, and crystals that cannot be dissolved in the solution treatment are present after the heat treatment. Decrease.

Further, the ratio of Mg to Cu represented by Mg / Cu is 2.5 or more. More preferably, Mg / Cu is 2.5 or more and 3.5 or less.
By strengthening with the Zn-Mg precipitation phase, which is the main strengthening phase, and further strengthening with the Al-Cu-Mg precipitation phase, an aluminum alloy with high strength can be obtained. If Mg / Cu is less than 2.5, Mg is consumed in forming Al-Cu-Mg-based precipitates, and the amount of Zn-Mg-based precipitates acting more effectively on the strength becomes relatively small. .

(Zr, Cr, Mn)
The processed aluminum alloy material of the present embodiment has a Zr (zirconium) content of 0.08% by mass to 0.25% by mass.
The processed aluminum alloy material of the present embodiment has a Cr (chromium) content of 0.02% by mass or more and 0.30% by mass or less.
The processed aluminum alloy material of the present embodiment may further contain Mn; 0.05% by mass or more and 0.32% by mass or less. The total content of Zr, Cr, and Mn is 0.12% by mass or more and 0.42% by mass or less.

In an aluminum alloy containing the above elements, during homogenization treatment, Al-Zr-based dispersed particles, and / or Al-Cr-based dispersed particles, and Al-Mn-based dispersed particles are formed, and the movement of crystal grain boundaries is suppressed. In other words, a so-called pinning effect is suppressed. Thereby, recrystallization is suppressed and the processed structure formed at the time of plastic working is maintained after the solution treatment, thereby contributing to the strength of the aluminum alloy.
If the total content of Zr, Cr, and Mn is more than 0.42% by mass, quenching sensitivity increases and T6 strength decreases. In particular, when the extrusion cross-sectional area is large, the cooling rate becomes slow, so that the strength cannot be obtained.

When the content of the above elements is such that Zr is less than 0.08% by mass, Cr is less than 0.02% by mass, and Mn is less than 0.05% by mass, the pinning effect is sufficient. It cannot be obtained and cannot contribute to strength. If the content of the above elements is such that Zr is more than 0.20% by mass and Cr is more than 0.30% by mass, the above coarse crystals are formed during casting, and the elongation of the aluminum alloy is reduced. I do.
Al-Cr-based dispersed particles and Al-Mn-based dispersed particles have an effect of enhancing stress corrosion cracking resistance, but Cr is less than 0.02% by mass and Mn is less than 0.05% by mass. This effect cannot be obtained sufficiently. This effect is considered to be caused by the Al-Cr-based dispersed particles and the Al-Mn-based dispersed particles capturing hydrogen atoms.

The remainder of the aluminum alloy processed material of the present embodiment other than the above-mentioned elements consists of Al and inevitable impurities. The aluminum alloy contains other elements as inevitable impurities derived from aluminum ingots and the like. If the content of the unavoidable impurities is 0.15% by mass or less for Si and 0.20% by mass or less for Fe, and more preferably 0.10% by mass or less for both, the effect of the present invention is not hindered. preferable.
Ti and B may be added as fine agents in the cast structure to prevent cracking of the ingot.

<Production method of aluminum alloy processed material>
One embodiment of the present invention is Zn: 9% by mass or more and 11% by mass or less, Mg: 2.0% by mass or more and less than 2.8% by mass, Cu: more than 0.8% by mass and 1.2% by mass or less. , Zr; 0.08% by mass or more and 0.25% by mass or less; Cr; 0.02% by mass or more and 0.30% by mass or less;
The balance consists of Al and unavoidable impurities, the content of Mg and Cu satisfies the relationship of Mg / Cu ≧ 2.5, and the total content of Zr and Cr is 0.12% by mass or more and 0.42% or more. Mass% or less, and is a method for producing an aluminum alloy processed material, wherein plastic working, solution treatment, quenching, and aging are sequentially performed.

  According to the method for manufacturing an aluminum alloy processed material of the present embodiment, a high-strength aluminum alloy processed material having the above-described composition and being subjected to plastic working, solution treatment, quenching, and aging sequentially. Can be manufactured.

(Plastic processing)
Examples of the plastic working include rolling, forging, extrusion, and drawing. The plastic working is preferably hot working in order to form a working structure. The most preferred plastic working is hot extrusion working at an extrusion ratio of 5 to 100 and an ingot temperature of 300 to 450 ° C. This is because the conditions are suitable for allowing the processed structure to remain until after the heat treatment.
Further, after the extrusion, plastic processing such as drawing or cutting may be performed in order to obtain a predetermined shape or size.

Before the plastic working, a homogenization treatment for homogenizing the crystallized substances and the like segregated at the time of casting and for forming Al-Zr-based, Al-Cr-based and Al-Mn-based precipitates ( (HO treatment) is more preferable. This is because this treatment affects the plastic workability and the formation of the processed structure.
By maintaining the holding conditions at 460 ° C. (450 ° C. to 470 ° C.) for 24 hours, elution elements such as Zn, Mg, and Cu can be homogenized, and sufficient strength can be obtained by a subsequent heat treatment. On the other hand, if the holding temperature is too high, there is a possibility that the resin is excessively melted. Further, the heating rate is more preferably 50 ° C./h or less. If the heating rate is high, the particle spacing of the Al-Zr-based, Al-Cr-based, and Al-Mn-based precipitates is widened, and it is easy to recrystallize during the solution treatment. That is, the heating rate is controlled in order to maintain the processed structure after the solution treatment.

(Solution treatment)
After the plastic working, a solution treatment is performed. In the solution treatment, the crystallized material is dissolved in the parent phase by maintaining the plastic work material at a high temperature.
The holding temperature during the solution treatment is preferably in the range of about 440C to about 470C. If the holding temperature is too high, local melting occurs and the strength of the plastically processed material decreases. On the other hand, if the holding temperature is low, Zn, Mg, and Cu cannot be sufficiently solid-dissolved, so that sufficient precipitation strengthening cannot be obtained by the subsequent aging treatment.

(Hardening process)
After the solution treatment, a quenching treatment is performed. By quenching the solution-processed plastic work material to room temperature, precipitation of crystallized solid solution in the mother phase is suppressed, and a supersaturated state is maintained.
In the quenching process, for example, water is used to quickly cool to room temperature. The cooling rate is preferably from 450 ° C. to 100 ° C. at a rate of 1000 ° C./min or more, followed by natural aging at room temperature for 2 days. By performing the quenching treatment under such conditions, a good supersaturated solid solution can be obtained.

(Aging treatment)
After the quenching process, an aging process is performed. As an aging treatment, the super-saturated Zn, Mg, and Cu in the mother phase are removed by heating and holding the quenched plastic work material at about 100 ° C. to about 180 ° C. -Precipitating finely and uniformly as an Mg-Cu-based compound to improve the strength of the plastically processed material.
If the solution treatment or quenching treatment is not performed, the amount of Zn, Mg, and Cu that are supersaturated in the mother phase will be insufficient, and the amount of the compound that precipitates during the aging treatment will decrease, and the strength will improve. Run out.

  The aging treatment condition (T6) for obtaining the highest strength is, for example, 10 to 30 hours at 100 to 180 ° C, more preferably 12 to 25 hours at 110 to 120 ° C. When other corrosion resistance is emphasized, the heat treatment of T73, T74, and T76 can be selected.

  In one embodiment of the present invention, in the above-described method for producing a processed aluminum alloy material, as the plastic working, an extrusion ratio of 5 to 100 and an ingot temperature of 300 to 450 ° C. are hot extruded, and 440 to 470 ° C. , A quenching process of cooling a range of 450 ° C. to 100 ° C. at a cooling rate of 1000 ° C./min or more, and an aging process at 100 ° C. to 180 ° C. for 10 hours to 30 hours.

  One embodiment of the present invention is as follows: Zn: 9 mass% to 11 mass%, Mg: 2.0 mass% to less than 2.8 mass%, Cu; more than 0.8 mass% to 1.2 mass% or less. , Zr: 0.08% by mass to 0.25% by mass, Cr: 0.02% by mass to 0.30% by mass, and Mn: 0.05% by mass to 0.32% by mass. Contained, with the balance being Al and unavoidable impurities, the content of Mg and Cu satisfying the relationship Mg / Cu ≧ 2.5, and the total content of Zr, Cr and Mn is 0.12 mass%. % Or more and not more than 0.42% by mass, and is a method for producing an aluminum alloy processed material, wherein plastic working, solution treatment, quenching and aging are sequentially performed.

In this manufacturing method, by containing Mn (manganese) in an amount of 0.05% by mass or more and 0.32% by mass or less, there is an effect of enhancing stress corrosion cracking resistance. Since Mn also has the same effect as Al-Cr-based dispersed particles, the above-described characteristics can be further improved.
In the aluminum alloy containing the above elements, at the time of the homogenization treatment, Al-Zr-based dispersed particles, and / or Al-Cr-based dispersed particles, and Al-Mn-based dispersed particles are formed, and the movement of crystal grain boundaries is suppressed. In other words, a so-called pinning effect is suppressed. Thereby, recrystallization is suppressed and the processed structure formed at the time of plastic working is maintained after the solution treatment, thereby contributing to the strength of the aluminum alloy. When the total content of Zr, Cr, and Mn is more than 0.42%, the quenching sensitivity increases and the T6 strength decreases. In particular, when the extrusion cross-sectional area is large, the cooling rate becomes slow, so that the strength cannot be obtained.

  In one embodiment of the present invention, in the above-mentioned aluminum alloy processed material, as the plastic working, the extrusion ratio is 5 to 100, and the ingot temperature is 300 to 450 ° C., and the hot extruding process is maintained at 440 to 470 ° C. A solution treatment, a quenching treatment for cooling a range of 450 ° C. to 100 ° C. at a cooling rate of 1000 ° C./min or more, and an aging treatment at 100 ° C. to 180 ° C. for 10 hours to 30 hours are sequentially performed.

  Further, in one embodiment of the present invention, the main crystal grain structure of the aluminum alloy processed material is a processed structure such as a fibrous structure. When heat treatment or the like is performed, recrystallization occurs, and a recrystallized structure may be generated in the structure of the outer peripheral portion.

  The aluminum alloy processed material according to the above embodiment can be used as leisure articles such as sports, industrial equipment, components for automobile parts and the like.

  Hereinafter, the present invention will be described using examples, but the present invention is not limited to these examples.

(Production of aluminum alloy test material)
Ingots of the components A to J in Table 1 below were obtained by continuous casting. The diameter of the ingot is 254 mm. These ingots were subjected to HO treatment (460 ° C., 24 hours, heating rate 50 ° C./h), and then cut into 800 mm lengths.

A test material was obtained by extruding each of the ingots of the above components A to J.
The diameter of the extruded material was 25 mm, and two pieces were extruded, and indirect extrusion was performed. The extrusion conditions were an extrusion ratio of 52, an ingot temperature of 380 ° C., and an extrusion speed of 1 m / min.

  Next, a solution treatment was performed. The solution temperature was 460 ° C. for 2 hours. Thereafter, the mixture was quickly cooled with water and naturally aged at room temperature for 3 days (quenching treatment). Thereafter, artificial aging was performed at 120 ° C. for 24 hours.

  As understood from Table 1, the compositions of Examples A and B satisfy the requirements of the present invention. The compositions of Examples C to J are outside the range defined by the present invention.

(Characteristic evaluation of aluminum alloy test material)
The strength of the aluminum alloy test material was evaluated by a tensile test. The tensile test was performed by processing a tensile test piece according to JIS 14A. The parallel part shape of the test piece was 10 mm in diameter and 60 mm in length, and the distance between gauge points was 50 mm. The tensile test was performed according to JIS2201.
The results of the tensile test are shown in [Table 2].

  The recrystallized structure formed on the outer peripheral portion of the extruded material was etched with a modified Tucker solution after polishing the extruded LT cross section, observed with a stereoscopic microscope, and its thickness was measured.

  In the tensile test, the tensile strength, 0.2% proof stress, and elongation at break were measured. In the tensile test, those satisfying these criteria based on a tensile strength of 770 MPa or more, a 0.2% proof stress of 750 MPa or more, and a breaking elongation of 8% or more were judged as acceptable.

Next, stress corrosion cracking resistance (SCC resistance) was evaluated for A, B, and C that passed the above tensile test.
A C-ring test piece was manufactured, and a stress corrosion cracking test (SCC test) was performed in accordance with JIS H8711. The C-ring test piece had an outer diameter of 19 mm and a thickness of 19 mm. As the stress, a stress corresponding to 75% of the proof stress was applied. The etchant was 3.5% NaCl, and 30 cycles were performed, with one cycle consisting of immersion in this aqueous solution for 10 minutes and drying for 50 minutes, and the presence or absence of cracks was determined.

  Those satisfying the target values of the above tensile properties and SCC resistance were evaluated as acceptable (O) in the overall evaluation.

  [Table 3] below shows the results of the characteristic evaluations for Examples A to J.

  According to the above results, A and B satisfied the conditions of 0.2% proof stress, elongation, and SCC resistance, and passed the comprehensive evaluation. From this result, it is understood that the aluminum alloy processed material specified in the present invention can obtain high strength.

C did not have satisfactory SCC resistance. This is presumably because the amount of Cr added is less than the lower limit specified in the present invention.
As for D, the result of 0.2% proof stress does not satisfy the acceptance criteria. This is considered to be because the amount of Cu added was larger than the upper limit specified in the present invention, and the Mg / Cu ratio was out of the range specified in the present invention, so that precipitation strengthening was insufficient.
E shows that the result of 0.2% proof stress does not satisfy the acceptance criteria. This is considered to be because the amount of Cu added was larger than the upper limit specified in the present invention, and the Mg / Cu ratio was out of the range specified in the present invention, so that precipitation strengthening was insufficient.

As for F, the result of 0.2% proof stress did not satisfy the acceptance criteria. This is because the amount of Zn added is smaller than the value specified, the amount of Cu added is larger than the upper limit specified in the present invention, and the Mg / Cu ratio is out of the range specified in the present invention. Probably because it was insufficient.
G shows that the elongation results do not meet the acceptance criteria. This is considered to be because the amount of Zn added was larger than the upper limit specified in the present invention, and the crystallized portion increased.

As for H, the results of 0.2% proof stress and elongation do not satisfy the acceptance criteria. This is because the addition amount of Mg is larger than the upper limit specified in the present invention, the Mg / Cu ratio is outside the range specified in the present invention, and Mg + Cu is larger than the upper limit specified in the present invention. It is thought that this was due to an increase in
As for I, the result of 0.2% proof stress does not satisfy the acceptance criteria. This is considered to be because the amount of Mg added was less than the lower limit specified in the present invention, the Mg / Cu ratio was outside the range specified in the present invention, and the precipitation strengthening was insufficient.
As for J, the result of 0.2% proof stress did not satisfy the acceptance criteria. Since the addition amounts of Zr and Cr are less than the lower limit specified in the present invention, it is considered that an extruded structure was not formed and a desired strength was not obtained.

  From the above results, it is understood that the aluminum alloy processed material satisfying the composition specified in the present invention can obtain higher strength than the aluminum alloy processed material not satisfying the composition specified in the present invention.

Claims (3)

Zn: 9% by mass to 11% by mass, Mg: 2.0% by mass to less than 2.8% by mass, Cu: more than 0.8% by mass to 1.2% by mass, Zr: 0.08% by mass Not less than 0.25% by mass and Cr; not less than 0.02% by mass and not more than 0.30% by mass;
The balance consists of Al and inevitable impurities,
The content of Mg and Cu satisfies the relationship of Mg / Cu ≧ 2.5, and the total content of Zr and Cr is 0.12% by mass or more and 0.42% by mass or less. A method for producing a processed aluminum alloy material , comprising: a crystal grain structure including a fibrous structure; and a recrystallized structure having a recrystallized thickness of 1.0 mm or less. A manufacturing method comprising sequentially performing processing, solution treatment, quenching, and aging . The aluminum alloy processing material further contains Mn; 0.05 to 0.32% by mass, and the total content of Zr, Cr and Mn is 0.12 to 0.42% by mass. The method according to claim 1, wherein: Homogenization treatment at a heating rate of 50 ° C./h or less,
As the plastic working, an extrusion ratio of 5 to 100 and an ingot temperature of 300 ° C. to 450 ° C. are hot extruded.
Solution treatment maintained at 440 ° C. to 470 ° C.
A quenching process of cooling a range of 450 ° C. to 100 ° C. at a cooling rate of 1000 ° C./min or more;
The method according to claim 1, wherein the aging treatment is sequentially performed at 100 ° C. to 180 ° C. for 10 hours to 30 hours.