JPH11172359A - Screw made of high strength aluminum alloy and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To produce a screw (bolt) made of an aluminum alloy in which the length of crystal grains in the longitudinal direction is regulated to <=100 μm, tensile strength regulated to <=350 N/mm<2> , proof stress is regulated to <=300 N/mm<2> , elongation is regulated to >=6%, and torsional strength is regulated to the value higher than that of AL3 (A6061-T6) by >=10%. SOLUTION: An aluminum alloy contg., by weight, 0.5 to 1.5% Mg, 0.5 to 1.5% Si, 0.5 to l.5% Cu, 0.2 to 0.5% Mn, 0.005 to 0.l% Ti, 0.001 to 0.05% B and 0.05 to 0.25% Zr, and the balance aluminum with inevitable impurities is melted to cast, the obtd. ingot is subjected to homogenizing treatment and is next worked into an wire element 1 for a screw by an extrusion method, a reduction method or a rolling method while annealing is suitably executed, the working ratio after final annealing in this wire element for a screw is regulated to >=40%, then, the wire element for a screw is annealed at a prescribed temp. and is formed into a screw 7, and this screw formed body is subjected to solution treatment, is thereafter rapidly cooled and is then subjected to artificial age hardening treatment.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a high-strength 6000
The present invention relates to a system-based aluminum alloy screw and a method for manufacturing the same.

[0002]

2. Description of the Related Art Steel screws used for assembling aluminum alloy structures (including bolts, hereinafter represented by screws)
Although there is no problem in strength, it is used by plating Zn or Ni because electrolytic corrosion occurs in a corrosive environment. However, when the plating is peeled off or the corrosive environment is particularly bad, electrolytic corrosion cannot be prevented. JI for steel screws
^SB - ^1051-1991 Standardized in "Mechanical Properties of Steel Bolts and Machine Screws". Stainless steel screws are compatible with aluminum alloys and are not easily eroded, so they are used in many aluminum alloy structures such as A6063 alloy window sashes. J for stainless steel screws
IS-B-1054 ^-1985 Standardized in "Mechanical properties of stainless steel corrosion-resistant screw parts".

[0003] In recent years, there has been a strong demand for material recycling from the viewpoints of effective use of earth resources, energy saving, and environmental cleanup. Aluminum requires an enormous amount of electrical energy to refine the raw material bauxite into bullion, but since aluminum has a low melting point, re-melting aluminum scrap does not require much energy and has a large recycling effect. However, if the scrap of the aluminum alloy structure is redissolved as it is, the steel or stainless steel screw is melted, and the purity of the obtained aluminum alloy is reduced. Removing the screws and re-melting is time-consuming and reduces the recycling effect by half.

[0004] The problem of the decrease in purity due to the re-melting can be solved by using aluminum alloy screws, and aluminum alloy screws are currently commercially available. In terms of recycling, for example, A6063 alloy window sashes
It is desirable to use screws of the same 6000 series alloy.
JIS-B-105 for aluminum alloy screws
^7-1989 Standardized in "Mechanical properties of non-ferrous metal screw parts".

On the other hand, in the automobile industry, efforts are being made to save energy and clean the environment, and the most influential measure is to reduce the weight of the vehicle body to aluminum to make it lighter. Regarding the structure of the aluminum body, a space frame type in which the body is mounted on a shape member serving as a bone is being studied from a conventional monocoque type in which a strength member is also used as a pressed plate. JIS-A which has high strength and excellent extrudability
It is likely that a 6000 series alloy will be used. It is expected that mechanical joints using reliable and energy-saving screws will be used extensively to replace the conventional resistance spot welding for joining sections and bodies. Recyclability is also required for automobiles having an aluminum body, and naturally aluminum alloy screws are used, and the alloy is desirably the same 6000 series alloy as the profile.

Incidentally, JIS-B-1057
^-1989 "Mechanical properties of non-ferrous metal threaded parts" includes AL1 (A5052), A1
L2 (A5056), AL3 (A6061), AL4
(A2024), AL5 (7N01), AL6 (A70
75) are standardized. Table 1 shows the specifications of screws (including bolts).

[0007]

[Table 1] (Note) Torsion strength of M4, unit: NM. The torsional strength is specified for each screw diameter.

Next, a conventional manufacturing process of the screw will be described. (1) AL1 (A5052) ... Casting → homogenization → extrusion → drawing → strand → → H16 material → cutting → completed → O material → header processing, thread rolling (H16) → completed (2) AL2 (A5056) …… Casting → homogenization processing → extrusion → drawing → element wire →→ H16 material → cutting → completed → O material → header processing, thread rolling (H16) → completed (3) AL3 (A6061)… … Casting → Homogenization → Extrusion → Drawing → Wire → → T6 processing → Cutting → Finishing → O material → Header processing, thread rolling → T6 processing → Completed (4) AL4 (A2024) …… Casting → Homogeneous Processing → Extrusion → Drawing → Wire → → T4 processing → Cutting → Completed → O material → Header processing, thread rolling → T4 processing → Completed (5) AL5 (A7N01) …… Casting → Homogenization processing → Extrusion → Drawing → Element wire →→ T6 processing → Cutting → Completion → O material → Header Work, thread rolling → T6 processing → completion (6) AL6 (A7075) …… Casting → homogenization processing → extrusion → drawing → wire → → T6 processing → cutting → completion → O material → header processing, screw rolling Manufacturing → T6 treatment → Completion

[0009]

Problems when the conventional screw produced in the above process is used for a window sash or an automobile are as follows. (1) Since AL1 (A5052) is not a 6000 series alloy, it has poor recyclability. The cutting material has low strength (30
0 N / mm ² or less), and the processing cost is high. Header processed and thread rolled materials have low strength (300 N / mm ² or less). (2) AL2 (5056) is inferior in recyclability because it is not 6000 type. Cutting materials are expensive. Since the header processed and thread rolled materials have poor workability, they are easily broken during processing. (3) With regard to AL3 (A6061), the processing cost of the cutting material is high. Header processed and thread rolled materials have poor workability and are easily cracked during processing. (4) AL4 (A2024) is inferior in recyclability because it is not 6000 type. Moreover, it is easily corroded. Cutting materials have high processing costs. Header processed and thread rolled materials have poor workability and are easily cracked during processing. (5) Since AL5 (A7N01) is not a 6000 series, it has poor recyclability. Moreover, it is easily corroded. Cutting materials have high processing costs. Header processed and thread rolled materials have poor workability and are easily cracked during processing. (6) AL6 (A7075) is inferior in recyclability because it is not 6000 type. Moreover, it is easily corroded. Cutting materials have high processing costs. Header processed and thread rolled materials have poor workability and are easily cracked during processing.

[0010] When a 6000 series alloy is required in the thread standard, there is AL3. AL3 (A6061-T6), the tensile strength of 320N / mm ^2, yield strength 250 N / mm ^2, elongation of 7%, the torsional strength (M4) 1.4N · m is standard value. Screws used in the assembly structure of automobiles are required to have a tensile strength of 350 N / mm ² or more, a proof stress of 300 N / mm ² or more, and an elongation of 6% or more. The torsional strength is changed from the conventional bolt and nut type to tapping screw type. Since there is a tendency to shift, a value higher than the standard value of AL3 by 10% or more is desired. Furthermore, it is also desired that they do not rust and that they are low in cost. The present invention has a tensile strength of 350 N / mm ² or more and a proof stress of 3
00N / mm ² or more, elongation 6% or more, torsional strength is AL
(3) It is an object of the present invention to provide a low-cost, high-strength aluminum alloy screw which is 10% or more of the standard value, has mechanical properties enough to withstand the assembly structure of an automobile, is hardly rusted, and is low in cost.

[0011]

According to the first aspect of the present invention,
Mg: 0.5 to 1.5 wt%, Si: 0.5 to 1.5 wt%
%, Cu: 0.5 to 1.5 wt%, Mn: 0.2 to 0.5
wt%, Ti: 0.005 to 0.1 wt%, B: 0.001
It is a high-strength aluminum alloy screw containing -0.05 wt% and Zr: 0.05-0.25 wt%, the balance being aluminum and unavoidable impurities.

The invention according to claim 2 is characterized in that Mg: 0.5 to
1.5 wt%, Si: 0.5 to 1.5 wt%, Cu: 0.5
-1.5 wt%, Mn: 0.2-0.5 wt%, Ti: 0.
005 to 0.1 wt%, B: 0.001 to 0.05 wt%,
Zr: contains 0.05 to 0.25 wt%, and contains Sc,
When at least one of the rare earth element and V is contained and each is added alone, Sc: 0.05 to 1 wt%, rare earth element: 0.05 to 1 wt%, V: 0.05 to 0.5 wt%
%, And when two or more kinds are added simultaneously, the total amount of the respective additions is 0.05 to 0.7 wt%, and the balance is aluminum and unavoidable impurities. .

The invention according to claim 3 is characterized in that Mg: 0.5 to
1.5 wt%, Si: 0.5 to 1.5 wt%, Cu: 0.5
-1.5 wt%, Mn: 0.2-0.5 wt%, Ti: 0.
005 to 0.1 wt%, B: 0.001 to 0.05 wt%,
An aluminum alloy containing 0.05 to 0.25 wt% of Zr, the balance being aluminum and unavoidable impurities is melted and cast, and the obtained ingot is homogenized. After being processed into a thread for a screw by either a drawing method or a rolling method, the working rate after final annealing of the thread for a screw is set to 40% or more, and then the wire for a screw is annealed at a predetermined temperature, The wire is formed into a screw, the screw formed body is solution-treated, rapidly cooled, and then subjected to artificial age hardening to reduce the length of crystal grains in the longitudinal direction to 20 mm.
0 μm or less, tensile strength of 350 N / mm ² or more, proof strength of 300 N / mm ² or more, elongation of 6% or more, and torsional strength of AL3 (A6061-T) of JIS-B- ^1057-1989.
A method for manufacturing a high-strength aluminum alloy screw, characterized in that the screw strength is set to a value 10% or more higher than the screw strength of 6).

The invention according to claim 4 is characterized in that Mg: 0.5 to
1.5 wt%, Si: 0.5 to 1.5 wt%, Cu: 0.5
-1.5 wt%, Mn: 0.2-0.5 wt%, Ti: 0.
005 to 0.1 wt%, B: 0.001 to 0.05 wt%,
Zr: contains 0.05 to 0.25 wt%, and contains Sc,
When at least one of the rare earth element and V is contained and each is added alone, Sc: 0.05 to 1 wt%, rare earth element: 0.05 to 1 wt%, V: 0.05 to 0.5 wt%
%, And when two or more kinds are added at the same time, the total of the respective addition amounts is 0.05 to 0.7 wt%, and the aluminum alloy consisting of the remaining aluminum and unavoidable impurities is melted and cast, and the obtained ingot is cast. Homogenization treatment and then, while appropriately annealing, are processed into a thread for screw by any one of extrusion method, drawing method, or rolling method, and the working rate of the screw wire after final annealing is 40% or more. Then, after annealing the element wire for a screw at a predetermined temperature, the element wire is formed into a screw, the screw formed body is subjected to a solution treatment, quenched, and then subjected to an artificial age hardening treatment to obtain a longitudinal crystal. The grain length is 200 μm or less, the tensile strength is 350 N / mm ² or more,
Strength of 300N / mm ² or more, elongation of 6% or more, the torsional strength of the ^{JIS-B-1057 -1989 AL3 (} A606
1-T6) A method for producing a high-strength aluminum alloy screw, wherein the screw strength is set to a value higher than the screw strength by 10% or more.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, Mg and Si are the main constituent elements of the screw of the present invention and contribute to the improvement of strength. Mg
When Si and Si coexist, Mg ₂ Si is precipitated by quenching and artificial age hardening, and the strength is improved. In the present invention, 0.5 to 1.5 wt% of Mg, 0.5
The reason for specifying each in the range of .about.1.5 wt% is 0.1.
If the amount is less than 5% by weight, the strength is not sufficiently improved, and if the amount exceeds 1.5% by weight, tensile properties, torsional strength, header workability, and rolling workability are reduced.

Cu contributes to strength improvement together with Mg and Si. The reason for defining the content to be 0.5 to 1.5 wt% is that if the content is less than 0.5%, the effect cannot be sufficiently obtained.
If the content exceeds 5% by weight, the tensile properties, torsional strength, header workability, rolling workability, and corrosion resistance decrease.

Mn partially forms a solid solution in the matrix and contributes to improvement in strength. Al-Fe contained as impurities
The Al-Fe-Mn-based rod-like compound is formed by combining with the base compound, and contributes to the improvement of the header workability and the rolling workability. Further, Mn promotes the precipitation of Mg ₂ Si. M
If n is less than 0.2 wt%, the effect cannot be sufficiently obtained.
If it exceeds 1.5 wt%, huge inclusions are formed, and the tensile properties, torsional strength, header workability, and rolling workability decrease. Therefore, Mn is contained in an amount of 0.2 to 0.5% by weight.

[0018] Ti and / or B improves cast cracking properties, and also improves header workability and roll workability. Ti is less than 0.005 wt% or B is 0.001
If the content is less than 0.1 wt%, the effect cannot be sufficiently obtained.
If the content of B exceeds 0.05% by weight or B exceeds 0.05% by weight, coarse inclusions are formed and the tensile properties, torsional strength, header workability, and rolling workability decrease. Therefore, Ti is set to 0.
005 to 0.1 wt%, and B is 0.001 to 0.05 wt%.

Zr prevents coarsening of crystal grains during heat treatment, and particularly enhances header workability and roll workability. If the content of Zr is less than 0.05 wt%, the effect cannot be sufficiently obtained, and if it exceeds 0.25 wt%, coarse inclusions are formed, and tensile properties, torsional strength, header workability,
And rolling workability falls.

Sc, rare earth elements, and V all contribute to the refinement of the crystal structure, and also improve the tensile strength, torsional strength, header workability, and roll workability. When Sc, a rare earth element, and V are used alone, 0.05 wt%
If the content is less than 1 wt%, the content of V is 0.5% or less.
If the content exceeds wt%, coarse inclusions are formed, and the tensile properties, torsional strength, header workability, and rolling workability decrease.
When two or more of Sc, rare earth element, and V are contained, the effect cannot be sufficiently obtained if the sum of the respective contents (wt%) is less than 0.05 wt%. If the sum of the amounts exceeds 0.7 wt%, coarse inclusions are formed, and the tensile properties, torsional strength, header workability, and rolling workability decrease.

As rare earth elements, La, Ce, Pr,
One or more of Nd, Sm and the like can be used, and the content of any one of them or the total content of two or more thereof may be in the range of 0.05 to 1 wt%. . As an alloy containing two or more of the above elements,
For example, there is a misch metal containing Ce and La as main components (usually, 45 to 50% by weight of Ce, 20 to 40% by weight of La, and a balance of other rare earth elements (Pr, Nd, Sm, etc.) and inevitable impurities). Each of the above-mentioned rare earth elements and misch metals has the same effect, but in terms of price, misch metal is more inexpensive than rare earth elements alone.

In the present invention, the alloy is melted and cast by a conventional method, and the obtained ingot is subjected to a homogenization treatment.
By extrusion, drawing, or rolling, the wire is processed into a screw wire while annealing. In the present invention, the reason why the working rate after the final annealing of the thread for a screw is 40% or more is that if the working rate is less than 40%, the subsequent annealing is performed.
Although Zr is added, the crystal grains become coarse, header workability and rolling workability are reduced, and defects such as cracks are easily generated during screw working. When the working degree after the final annealing of the screw wire is set to 40% or more, the crystal grains do not become coarse even in the subsequent annealing due to the synergistic effect with Zr, and the crystal grains remain fine, and the header processing and rolling of the screw are performed. Defects such as cracks do not occur during fabrication, and the fabrication is facilitated.

The thread for a screw is annealed so as to facilitate threading and the like, and then processed into a screw shape by header processing and rolling. Next, quenching and artificial age hardening are performed to increase the strength and complete the screw. By processing in such a process, the average length of the crystal grains in the longitudinal direction of the screw is suppressed to 200 μm or less. Further, the tensile strength is 350 N / mm ² or more, the proof stress is 300 N / mm ² or more, the elongation is 6% or more, and the torsional strength is JIS-B-105.
The value can be increased by 10% or more than that of AL3 (A6061-T6) of 7 ^{−1 989} . In the present invention, the reason for suppressing the average length of crystal grains in the longitudinal direction of the screw to 200 μm or less,
If the thickness exceeds 200 μm, the toughness is reduced and the screw is cracked when tightened. The average length of the crystal grains is 1
It is particularly desirable that the thickness be 00 μm or less.

[0024]

EXAMPLES (Example 1) Aluminum alloys of the present invention compositions shown in Nos. 1 to 27 in Table 2 were cast into billets of 219 mmφ by a semi-continuous casting method, and the obtained ingot was cut into a length of 300 mm. This was homogenized at 540 ° C. for 4 hours.
The wire was hot-extruded at 70 ° C. to obtain a wire having a diameter of 9 mm, and this wire was processed into a strand having a diameter of 3.46 mm by a manufacturing process A shown in Table 4. Next, the strand 1 is cut into a predetermined length by a cutting machine 2 (FIG. 1A), and a head 4 is formed by a header processing machine 3 (FIG. 1B). 6 was formed (FIG. 1C, D). Next, after heating at 540 ° C. for 1 hour and then water quenching, an artificial age hardening treatment was performed at 180 ° C. for 8 hours to produce M4 screws. The dimensions of the M4 screw 7 are shown in FIG. In the case of poor workability, cracks occurred at the base of the head and the cross-groove during the formation of the head, and cracks occurred at the thread during the rolling process.

(Comparative Example 1) Aluminum alloys other than the compositions of the present invention shown in Nos.
into a billet with a diameter of 300 mm.
mm, and homogenized at 540 ° C. for 4 hours.
Next, the material was hot-extruded at 470 ° C. to obtain a wire having a diameter of 9 mm. The wire was formed into a strand having a diameter of 3.46 mm by the manufacturing process B shown in Table 4.
No. 4 screws were manufactured.

(Conventional example 1) Conventional alloys (A6061, A5052, A5056, A202) shown in No. 50 to No. 54 of Table 3
4, A7N01) was cast into a 219 mmφ billet by a semi-continuous casting method, and the obtained ingot was processed in the same manner as in Comparative Example 1 to produce an M4 screw.

With respect to each of the obtained screws, thread workability (header workability, screw rollability) was examined. Further, a tensile test, a torsion test, a microstructure observation of a cross section in a longitudinal direction, and a corrosion test were performed. The results are shown in Tables 4 to 7. The test, observation method, or criteria for good or bad are shown below. (1) Header processability: header process was performed without any problem ... good (○). Cracked during header processing ..... Defective (x). (2) Rolling workability: M4 screw processing was performed without any problem ... good (O). Cracked during M4 thread rolling ..... Poor (x). (3) Tensile properties: As shown in FIG. 3, a tensile test was performed with an M4 screw 7 sandwiched between an upper chuck 8 and a lower chuck 9. Those having a tensile strength of 350 N / mm ² or more: good (○). Those having a tensile strength of less than 350 N / mm ² ... poor (x). Those with a proof stress of 300 N / mm ² or more: good (○). Those with a proof stress of less than 300 N / mm ² ... poor (x). Those with an elongation of 6% or more: good (O). Those with an elongation of less than 6%: poor (x). (4) Torsion strength: As shown in FIG. 4, after turning the handle 11 to the fixing jig 10 and firmly fixing the M4 screw 7, until the M4 screw 7 is broken by the plus screwdriver 13 attached to the torque meter 12. It was turned to determine the torque value (torsional strength) at break. The reference value for torsional strength is AL3
1.54N ・ 10% or more higher than the standard value of 1.4N ・ m
m. Good in torsional strength of 1.54 N · m or more. Those with a torsional strength of less than 1.54 N · m: defective (x). (5) Measurement of crystal grain length: As shown in FIGS. 5 (a) and 5 (b), the M4 screw 7 is cut vertically, its cross section is polished, then etched, and a metal microscope section 14 is used. Was observed, and the length 15 in the longitudinal direction of each crystal grain was measured for 50 crystal grains. Those having an average value of 200 μm or less: good (○). Those with an average value exceeding 200 μm: poor (×). (6) Corrosion test method: As shown in FIG. 6, an A6063 alloy plate (3 × 100
(× 100 mm) 17 was tightened to obtain a test body, which was immersed in a 5% saline solution 19 in a stainless steel tank 18.
The specimen was placed on an insulating bakelite table 20. After a lapse of 1000 hours, the test specimen was taken out and the state of corrosion was examined. Corrosion resistance equivalent to bolts made of A6061 .......... Good (O). Inferior to A6061 bolts in corrosion resistance .......... Poor (x).

[0028]

[Table 2]

[0029]

[Table 3]

[0030]

[Table 4]

[0031]

[Table 5]

[0032]

[Table 6]

[0033]

[Table 7]

[0034]

[Table 8]

[0035]

[Table 9]

[0036]

[Table 10]

[0037]

[Table 11]

As is clear from Tables 5 to 11, all of Examples Nos. 1 to 54 (Tables 5 to 8) of the present invention are excellent in workability, screw tensile test, torsion test, microstructure and corrosion test. No.77-86 (Table 1)
1) It was better. Manufacturing process (Table 4)
With regard to, A exhibited better properties than B with respect to the tensile test, the torsion test, and the microstructure of the screw. On the other hand, in Comparative Examples Nos. 55 to 76 (Tables 9 and 10), since the alloy composition was not the composition of the present invention, one of the characteristics was poor and the overall evaluation was poor.

Example 2 An aluminum alloy having the composition of the present invention shown in Nos. 1 to 27 of Table 2 was 219 mmφ by a semi-continuous casting method.
And the resulting ingot was cut into a length of 300 mm, homogenized at 540 ° C. for 4 hours, and then hot extruded at 470 ° C. to obtain a 10 mmφ wire. It was processed into a 7.1 mmφ element wire by the manufacturing process C shown below. Next, the strand 21 is cut into a predetermined length by the cutting machine 2 (FIG. 7A), and this is subjected to header processing in two stages of round head → hexagonal head to form a head 24 (FIG. 7B, C) A thread portion 26 is formed by a thread rolling machine (FIG. 7D).
After heating at 40 ° C for 1 hour and water quenching,
An M8 bolt 27 was manufactured by performing an artificial age hardening treatment for a time. The dimensions of the M8 bolt 27 are shown in FIG. In the case of poor workability, cracks occurred at the base of the head and the cross groove at the time of forming the head, and cracks occurred at the thread during the rolling process.

Comparative Example 2 Aluminum alloys other than the compositions of the present invention shown in Nos.
into a billet with a diameter of 300 mm.
mm, and homogenized at 540 ° C. for 4 hours.
Next, it is hot-extruded at 470 ° C. to form a 10 mmφ wire,
This wire was made into a 7.1 mmφ wire by the manufacturing process D shown in Table 9, and this wire was processed in the same manner as in Example 2 to obtain
Eight bolts were manufactured.

(Conventional example 2) Conventional alloys (A6061, A5052, A5056, A202) shown in No. 50 to No. 54 of Table 3
4, A7N01) was cast into a 219 mmφ billet by a semi-continuous casting method, and the obtained ingot was worked in the same manner as in Comparative Example 2 to produce an M8 bolt.

For each of the obtained screws, thread workability (header workability, thread rolling property) was examined. Further, a tensile test, observation of a microstructure of a cross section in a longitudinal direction, and a corrosion test of the screw were performed in the same manner as in Example 1. Table 10-1
It is shown in FIG.

[0043]

[Table 12]

[0044]

[Table 13]

[0045]

[Table 14]

[0046]

[Table 15]

[0047]

[Table 16]

[0048]

[Table 17]

[0049]

[Table 18]

As is clear from Tables 12 to 18, all of Nos. 87 to 140 (Tables 12 to 15) of the present invention show good properties in workability, screw tensile test, microstructure and corrosion test. Overall, it was better than Nos. 163 to 167 of the conventional example (Table 18). In the production process (Table 9), C exhibited better characteristics than D in the tensile test, torsion test, and microstructure of the screw. In contrast, No. 1 of the comparative example
For 41 to 162 (Tables 16 to 17), since the alloy composition was out of the composition of the present invention, one of the properties was poor and the overall evaluation was poor.

Although the description has been given of the aluminum alloy screws (including bolts), the same effects can be obtained by applying the present invention to nuts, and the present invention is used in combination with the screws (including bolts) of the present invention. Thereby, a larger effect can be obtained.

[0052]

As described above, the high-strength aluminum alloy screws (including bolts) of the present invention have a tensile strength of 350 N / mm ² or more and a proof stress of 300 N / mm ² or more.
Elongation of 6% or more, torsional strength of JIS-B-1057
10% or more of AL3 (A6061-T6) of ^-1989 , average grain length of 200 μm or less in longitudinal method, sufficient tensile properties and torsional strength as screws and bolts for joining aluminum alloy structures In addition, it has stress corrosion cracking resistance and stable high joint strength can be obtained. It also has excellent header workability and thread rolling workability and is easy to work. Further, since the screw of the present invention is a 6000 series alloy, for example, when used for joining a 6000 series alloy structure such as a sash or an automobile, the scrap is less likely to decrease in purity due to re-melting of the scrap and has excellent recyclability. Further, the screw of the present invention can be easily manufactured by a normal manufacturing method in which manufacturing conditions are partially defined. Therefore, an industrially remarkable effect is achieved.

[Brief description of the drawings]

BRIEF DESCRIPTION OF THE DRAWINGS FIGS. 1A to 1D are explanatory views of a forming process of an M4 screw.

FIG. 2 is an explanatory diagram of dimensions of an M4 screw.

FIG. 3 is a schematic diagram of a tensile test of a screw.

FIG. 4 is a perspective view of a torsion tester.

5A is a diagram illustrating a test piece for measuring a crystal grain length, and FIG. 5B is an explanatory view of a method for measuring a crystal grain length.

FIG. 6 is an explanatory diagram of a corrosion test method.

FIGS. 7A to 7D are explanatory diagrams illustrating forming of an M8 bolt.

FIG. 8 is an explanatory diagram of dimensions of an M8 bolt.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Wire for M4 screw 2 Cutting machine 3 Header processing machine 4 Head of M4 screw 5 Screw rolling machine 6 Thread part of M4 screw 7 M4 screw 8 Upper chuck 9 Lower chuck 10 Fixing jig 11 Handle 12 Torque meter 13 Phillips screwdriver 14 M4 screw crystal grain length measuring point 15 crystal grain length 16 nut 17 A6063 alloy plate 18 stainless steel tank 19 saline solution 20 bakelite table 21 M8 bolt strand 24 M8 bolt head 26 M8 bolt Thread part 27 M8 bolt

Continuation of the front page (51) Int.Cl. ⁶ identification code FI C22F 1/00 630 C22F 1/00 630A 631 631A 685 685Z 694 694A

Claims (4)

[Claims] 1. Mg: 0.5-1.5 wt%, Si: 0.1.
5 to 1.5 wt%, Cu: 0.5 to 1.5 wt%, Mn:
0.2-0.5 wt%, Ti: 0.005-0.1 wt%,
B: 0.001 to 0.05 wt%, Zr: 0.05 to 0.
A high-strength aluminum alloy screw containing 25 wt%, the balance being aluminum and unavoidable impurities. 2. Mg: 0.5-1.5 wt%, Si: 0.
5 to 1.5 wt%, Cu: 0.5 to 1.5 wt%, Mn:
0.2-0.5 wt%, Ti: 0.005-0.1 wt%,
B: 0.001 to 0.05 wt%, Zr: 0.05 to 0.
25 wt% and at least one of Sc, rare earth element, and V, when each is added alone, Sc: 0.05-1 wt%, rare earth element: 0.05-
1 wt%, V: 0.05 to 0.5 wt%, and when two or more kinds are added at the same time, the total amount of each addition is 0.1%.
A high-strength aluminum alloy screw, characterized in that the amount is from 0.5 to 0.7 wt% and the balance is aluminum and unavoidable impurities. 3. Mg: 0.5-1.5 wt%, Si: 0.
5 to 1.5 wt%, Cu: 0.5 to 1.5 wt%, Mn:
0.2-0.5 wt%, Ti: 0.005-0.1 wt%,
B: 0.001 to 0.05 wt%, Zr: 0.05 to 0.
An aluminum alloy containing 25 wt%, the balance being aluminum and unavoidable impurities is melted and cast, and the obtained ingot is homogenized, and then, while appropriately annealing,
The screw wire is processed by any one of the extrusion method, the drawing method, and the rolling method, the working rate of the screw wire after the final annealing is set to 40% or more, and then the screw wire is annealed at a predetermined temperature. After that, the wire is formed into a screw, the screw formed body is subjected to a solution treatment, quenched, and then subjected to an artificial aging hardening treatment to have a crystal grain length in the longitudinal direction of 200 μm or less and a tensile strength of 350 N / mm ² or more, proof stress of 300 N / mm ² or more, elongation of 6% or more, and torsional strength of JIS-B-105.
High intensity manufacturing method of an aluminum alloy screw, characterized by a high value of 10% or more than the screw strength of 7 ^-1989 of AL3 (A6061-T6). 4. Mg: 0.5-1.5 wt%, Si: 0.
5 to 1.5 wt%, Cu: 0.5 to 1.5 wt%, Mn:
0.2-0.5 wt%, Ti: 0.005-0.1 wt%,
B: 0.001 to 0.05 wt%, Zr: 0.05 to 0.
25 wt% and at least one of Sc, rare earth element, and V, when each is added alone, Sc: 0.05-1 wt%, rare earth element: 0.05-
1 wt%, V: 0.05 to 0.5 wt%, and when two or more kinds are added at the same time, the total amount of each addition is 0.1%.
An aluminum alloy consisting of aluminum and unavoidable impurities is melted and cast, and the obtained ingot is homogenized, and then subjected to extrusion, drawing, or rolling while appropriately annealing. After the final annealing of the screw wire is made 40% or more, and then the screw wire is annealed at a predetermined temperature, and then the wire is turned into a screw. The screw formed body is subjected to solution treatment, then quenched, and then subjected to an artificial age hardening treatment to have a crystal grain length in the longitudinal direction of 200 μm or less, a tensile strength of 350 N / mm ² or more, and a proof stress of 300 N / mm ^{2. Two}
The elongation is 6% or more, and the torsional strength is JIS-B-10.
57 ^{-1 989} AL3 high intensity method of manufacturing an aluminum alloy screw, characterized by a high value of 10% or more than the screw strength of (A6061-T6).