JPH09249931A - High corrosion resistant aluminum alloy excellent in machinability - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a high corrosion resistant aluminum alloy excellent in machinability and suitable, e.g. for machine parts requiring frequent use of machining in their manufacturing process. SOLUTION: This aluminum alloy has a composition consisting of, by mass, 1.5-12.0% Si, 0.5-6.0% Mg, 0.01-0.1% Ti, and the balance Al with inevitable impurities and containing, if necessary, either or both of 0.5-2.0%, by mass, Mn and 0.1-1.0% Cu or one or more kinds among 0.5-1.0% Fe, 0.1-0.5% Cr, and 0.1-0.5% Zr.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a highly corrosion-resistant aluminum alloy having excellent machinability, which is suitable for machine parts and the like that frequently use cutting during manufacturing.

[0002]

2. Description of the Related Art Among aluminum alloys, non-heat-treatable alloys, mainly 3000-series Al-Mn alloys, have moderate mechanical properties, excellent corrosion resistance and cold forgeability, and can be formed at low cost. Since it is possible, it is often used for machine parts and the like. At that time, it is generally commercialized by cold forging, followed by cutting and drilling. However, this type of alloy has difficulty in cutting chips generated at the time of cutting and is inferior in machinability, so that it has been difficult to employ it in machine parts that require complicated cutting and drilling.

[0003] Among aluminum alloys, non-heat-treated alloys, mainly 5000-series Al-Mg-based alloys, have moderate mechanical properties (slightly higher in strength level than 3000 series), corrosion resistance and cold working. It has excellent performance and can be processed at low cost, so it has many uses for optical devices and other mechanical parts such as cameras and microscope tubes. In that case, cutting and drilling are generally performed after cold forging. Has been commercialized. However, this type of alloy is inferior in machinability due to the difficulty in cutting chips generated during cutting, and it has been difficult to employ it in machine parts that require complicated cutting and drilling.

On the other hand, a conventional high machinability aluminum alloy is an AA6262 alloy (Si: 0.4
0.8% by mass, Mg: 0.8% to 1.2% by mass, Cu:
0.15 to 0.4% by mass, Pb: 0.4 to 0.7% by mass, Bi: 0.4 to 0.7% by mass, balance Al) It contains low melting point metals such as Bi and Sn (see JP-A-54-143714 and JP-A-3-39442). These low-melting metals hardly form a solid solution in aluminum, but micro-segregate in granular form in the aluminum alloy, and the low-melting metal particles are melted by the heat generated during the cutting process to cut chips and cut the aluminum alloy. Improve the performance.

[0005] The above-mentioned AA6262 alloy is a mechanical part that is frequently used for cutting, especially drilling in the manufacturing process.
For example, a heat-treated aluminum alloy conventionally used as a material for a housing of an anti-skid brake system of an automobile, such as Pb, Bi,
It is expected that the effect of improving the machinability by the addition of a low melting point metal such as Sn can be obtained not only in the above-mentioned heat-treated alloy but also in the non-heat-treated alloy (for example, Japanese Patent Application Laid-Open No. Hei 3-3).
No. 9442).

[0006]

However, aluminum alloys to which these low-melting-point metals have been added improve machinability, but on the other hand, have low corrosion resistance, and low-melting-point metals also have the disadvantage of causing thermal embrittlement. Had to pay close attention to Further, when the alloy is recycled as scrap, it can be diverted only to a relatively small number of alloy species that require Pb, Bi, etc., and the diverted range is narrowed, which is disadvantageous in recyclability.

[0007] Further, in order to enhance corrosion resistance, abrasion resistance or decorative effect, mechanical parts may be subjected to alumite treatment on the surface. In the case of an aluminum alloy to which Pb or Bi is added, Pb or Bi is added to the surface. There is a problem that an oxide film is not formed at an exposed portion, and only an alumite film having a non-uniform and low gloss can be obtained.

A non-heat treatment type aluminum alloy which does not contain such a low melting point metal and has improved machinability is disclosed in JP-A-60-
Although proposed in Japanese Patent No. 184658, Pb, B
The machinability was not sufficient as compared with an aluminum alloy containing a low melting point metal such as i or Sn.

The present invention has been made in view of the above-mentioned problems of the prior art. In general, it is possible to obtain an aluminum alloy excellent in both machinability and corrosion resistance, and to provide a recyclable and uniform alumite. The object is to obtain an aluminum alloy having excellent machinability capable of forming a film. Individually speaking, the non-heat treatment type which has the same mechanical properties, cold forgeability, corrosion resistance, and recyclability as the conventional 3000 series or 5000 series non-heat treatment type aluminum alloys and which has improved machinability It is an object to obtain an aluminum alloy, and to obtain a heat-treatable aluminum alloy having a machinability equal to or higher than that of a conventional AA6262 alloy and having more improved corrosion resistance.

[0010]

As a result of intensive studies to solve the above problems, the inventors of the present invention have found that low-melting-point metals such as Pb, Bi, Sn, etc., which have been added for the purpose of improving machinability in the past. Si is not added and does not hinder recyclability
It was found that the above object can be achieved by using Mg and Mg, and based on the findings, the present invention has been completed. As shown below, the present application relates to two systems of non-heat treatment type aluminum alloys having different strength levels (claims 1 to 5 and 6 to 9) and inventions to heat treatment type aluminum alloys (claims 10 to 10). 12) is included.

[Inventions 1 to 5] A highly corrosion resistant aluminum alloy excellent in machinability according to the present invention is Si: 1.
5 to 12.0 mass%, Mg: 0.5 to 6.0 mass%, T
i: 0.01 to 0.1% by mass, respectively, with the balance being Al and unavoidable impurities. Further, the highly corrosion-resistant aluminum alloy excellent in machinability according to the present invention, if necessary, in addition to the above alloy elements, Mn: 0.5 to 2.0 mass% or Cu: 0.1 to 1.0 mass%. One or both of the above, or Fe: 0.5 to 1.0% by mass, Cr: 0.1 to 0.5% by mass, Zr: 0.1 to 0.1% by mass.
One or more of 0.5 mass% is contained, or the above-mentioned elements are freely combined and contained.

The above-mentioned highly corrosion-resistant aluminum alloy having excellent machinability is superior in forgeability but inferior in machinability due to poor machinability, and thus has strength and corrosion resistance as compared with conventional 3003 alloy and 3004 alloy which cannot be applied to many machine parts. It is a non-heat treatment type aluminum alloy having the same cold forgeability and significantly improved machinability, which enables cold forging at low cost and enables complicated cutting. Further, the cutting ability of the cutting chips is good, and troubles such as winding of the cutting chips around the tool due to long cutting chips do not occur. In addition, P is used to improve machinability.
Since a low melting point metal such as b or Bi is not added, it has high corrosion resistance, heat brittleness cannot occur, and recyclability is not hindered. The aluminum alloy can be manufactured according to a conventional method. For example, the extruded material can be melted, cast, homogenized and heat-treated, and then extruded to be used as a material for forging.

Next, the reasons for adding each element and the reasons for limiting the amount of addition to the aluminum alloy will be described.

Si: 1.5 to 12.0 mass% Si forms a Si-based compound in the aluminum structure to improve the cutting property of cutting chips and improve the machinability. This is because the Si-based compound serves as a starting point for cutting chips. The lower limit of Si addition must exceed the solid solubility limit of 1.5% in aluminum. To clarify the effect of Si, addition of more than 2.0% is desirable. A remarkable effect can be obtained by adding 0.0% or more. Therefore, from the viewpoint of obtaining excellent machinability, S
i is preferably 2.0 to 12.0 (not including 2.0)% or 4.0 to 12.0%. On the other hand, the upper limit of addition of Si does not cause deterioration of extrudability and embrittlement of the extruded material due to increase in deformation resistance due to formation of coarse primary crystal Si,
It must be 12.0% or less of the eutectic point. In particular, the extrudability is desirably 6% or less.

Mg: 0.5 to 6.0% by mass Mg has the effects of improving the strain hardening ability and thus improving the chip breaking property, and also forming a solid solution to increase the strength of the material.
If the Mg content is less than 0.5%, the effect cannot be sufficiently obtained, and if the Mg content exceeds 6.0%, the deformation resistance increases and the extrudability decreases. From the viewpoint of securing strength and good extrudability, it is preferably about 1.0% or more and 3.0% or less. However, from the viewpoint of exclusively suppressing deformation resistance during extrusion and improving extrudability. , Less than 1.0%, particularly 0.9% or less, a remarkable effect can be obtained. Therefore, in that case, Mg is 0.5 to 1.0 (not including 1.0)%,
Alternatively, it may be 0.5 to 0.9%.

Ti: 0.01 to 0.1% by mass Ti makes the cast structure fine and stabilizes the mechanical properties.
However, if the Ti content is less than 0.01%, the effect cannot be obtained, while if the content exceeds 0.1%, the effect is saturated.

Mn: 0.5 to 2.0 mass% Mn has the effect of forming a solid solution to increase the strength of the raw material, and also has the effect of promoting cutting of chips in order to improve the strain hardening ability. However, if the Mn content is less than 0.5%, a sufficient effect cannot be obtained, while if it exceeds 2.0%, the extrudability decreases. In particular, from the viewpoint of securing strength and good extrudability, 0.7% or more and 1.5% or less are desired.

Cu: 0.1 to 1.0 mass% Cu has the effect of forming a solid solution to increase the strength of the material and also to promote chip breaking in order to improve the strain hardening ability.
It is added instead of or together with Mn. But C
If the u content is less than 0.1%, its effect is poor, while
If it is added in an amount exceeding 1.0%, the corrosion resistance decreases and the extrudability also decreases. In particular, from the viewpoint of securing strength and good corrosion resistance and extrudability, 0.3% or more and 0.8% or less are desired.

Fe: 0.5 to 1.0% by mass, Cr: 0.1 to 0.5% by mass, Zr: 0.1 to 0.5% by mass Fe, Cr and Zr are each a compound with Al. Formed,
Improves machinability by becoming the starting point for cutting chips. In the present invention, the inclusion of less than the lower limit as each inevitable impurity is allowed, but if it is less than the lower limit, the effect is not sufficient,
On the other hand, when the content exceeds the upper limit, a coarse compound is formed and the extrudability is lowered.

As the unavoidable impurities of the aluminum alloy, Pb, Bi, and Sn are allowed to be 0.05 mass% or less each in accordance with the chemical composition defined in JIS H4040. If these low melting point metals are contained in a large amount, the corrosion resistance of the aluminum alloy is degraded, but within this range, the properties are not affected. Also, other unavoidable impurities are individually allowed to be 0.05% by mass or less.

[Inventions 6 to 9] A highly corrosion-resistant aluminum alloy excellent in machinability according to the present invention is Si: 1.
5 to 12.0 mass% and Mg: 2.0 to 6.0 mass% are contained, and the balance is Al and inevitable impurities.
Further, the highly corrosion-resistant aluminum alloy excellent in machinability according to the present invention, if necessary, in addition to the above alloy elements, M
n: 0.3 to 1.2% by mass, Ti: 0.01 to 0.1% by mass, either or both, or F
e: 0.5 to 1.0% by mass, Cr: 0.1 to 0.5% by mass, Zr: 0.1 to 0.5% by mass, or at least one of the above, or The elements listed in both of these are freely combined and contained.

The high corrosion resistance aluminum alloy excellent in machinability described above is excellent in cold workability, but inferior in machinability, so that it cannot be applied to many machine parts and so on.
Compared with alloy and 5056 alloy, it is a non-heat treatment type aluminum alloy that has the same strength, corrosion resistance, and cold workability such as cold forging, and has significantly improved machinability, and an alloy that enables complex cutting work. Is. Further, the cutting ability of the cutting chips is good, and troubles such as winding of the cutting chips around the tool due to long cutting chips do not occur. In addition, Pb, Bi for improving the machinability
Since low-melting-point metals such as, for example, are not added, high corrosion resistance, thermal embrittlement cannot occur, and recyclability is not impaired. The aluminum alloy can be manufactured according to a conventional method. For example, the extruded material can be melted, cast, homogenized and heat treated, and then extruded to obtain a material for cutting.

Next, the reason for adding each element and the reason for limiting the amount of addition to the aluminum alloy will be described.

Si: 1.5 to 12.0 mass% Si forms a Si-based compound in the aluminum structure to improve the cutting property of cutting chips and improve the cutting property. This is because the Si-based compound serves as a starting point for cutting chips generated during cutting. The lower limit of Si addition must exceed the solid solubility limit of 1.5% in aluminum. To clarify the effect of Si, addition of more than 2.0% is desirable. A remarkable effect can be obtained by adding 0.0% or more. Therefore, from the viewpoint of obtaining excellent machinability, Si is preferably 2.0 to 12.0 (not including 2.0)%, or 4.0 to 12.0%.
On the other hand, the upper limit of the addition of Si needs to be 12.0% or less of the eutectic point in order to prevent the extrudability from being reduced or the embrittlement of the extruded material due to the increase in deformation resistance due to the formation of coarse primary crystal Si. There is. In particular, the extrudability is desirably 6% or less.

Mg: 2.0 to 6.0 mass% Mg has the effects of improving the strain hardening ability and thus improving the chip breaking property, and also forming a solid solution to increase the strength of the material.
If the Mg content is less than 2.0%, a sufficient effect cannot be obtained,
If added in excess of 6.0%, the deformation resistance increases and the extrudability decreases. Particularly, from the viewpoint of securing strength and good extrudability, 2.5% or more and 5.5% or less are desired.

Ti: 0.01 to 0.1 mass% Ti refines the cast structure and stabilizes the mechanical properties.
However, if the Ti content is less than 0.01%, the effect cannot be obtained, while if the content exceeds 0.1%, the effect is saturated.

Mn: 0.3 to 1.2% by mass Mn has the effect of forming a solid solution to increase the strength of the raw material, and also has the effect of promoting cutting of chips to improve the strain hardening ability. However, if the Mn content is less than 0.3%, a sufficient effect cannot be obtained, while if it is added over 1.2%, the extrudability deteriorates. Particularly, from the viewpoint of securing strength and good extrudability, 0.5% or more and 1.0% or less are desired.

Fe: 0.5 to 1.0% by mass, Cr: 0.1 to 0.5% by mass, Zr: 0.1 to 0.5% by mass Fe, Cr and Zr are each a compound with Al. Formed,
Improves machinability by becoming the starting point for cutting chips. In the present invention, the inclusion of less than the lower limit as each inevitable impurity is allowed, but if the content is less than the lower limit, the effect is not sufficient, while if it exceeds the upper limit, a coarse compound is formed and extrudability is lowered. To do.

As the unavoidable impurities of the aluminum alloy, Pb, Bi, and Sn are allowed to be 0.05 mass% or less for each, in accordance with the chemical composition defined in JIS H4040. If these low melting point metals are contained in a large amount, the corrosion resistance of the aluminum alloy is degraded, but within this range, the properties are not affected. Also, other unavoidable impurities are individually allowed to be 0.05% by mass or less.

[Inventions of Claims 10 to 12] A highly corrosion-resistant aluminum alloy excellent in machinability according to the present invention is Si:
1.5-12.0 mass%, Mg: 0.2-1.2 mass%, Cu: 0.15-3.0 mass%, respectively,
The balance consists of Al and unavoidable impurities. Further, the highly corrosion-resistant aluminum alloy excellent in machinability according to the present invention, if necessary, in addition to the above alloy elements, Cr: 0.04 to
0.35 mass% or Ti: 0.001-0.05 mass%
Either or both of are included.

The greatest feature of the high corrosion resistant aluminum alloy having excellent machinability is that Pb, B as in the AA6262 alloy.
That is, the machinability is improved without adding a low melting point metal such as i or Sn. This aluminum alloy extruded material is
Since no low-melting point metal is added, the alloy has higher corrosion resistance than the AA6262 alloy, and further, thermal brittleness cannot occur and recyclability is high. Further, the cutting ability of the cutting chips is good, and troubles such as winding of the cutting chips around the tool due to long cutting chips do not occur. Incidentally, the aluminum alloy, in accordance with a conventional method,
For example, it can be subjected to melting, casting, homogenization treatment, and then extrusion processing, and this extruded material is subjected to solution treatment, quenching, artificial aging treatment to give a predetermined strength, and then subjected to cutting processing.

Next, the reason for adding each element and the reason for limiting the amount added in the aluminum alloy will be described.

Si: 1.5 to 12.0 mass% Si forms a Si-based compound in the aluminum structure, improves cutting of chips and improves machinability. This is S
This is because the i-phase serves as the starting point of strain propagation and increases the propagation velocity of strain received from the tool during cutting. Therefore, the lower limit of Si addition is 1.5%, which is the solid solubility limit in aluminum.
It is necessary to exceed 2.0%, and in order to clarify the effect of Si, it is desirable to add over 2.0%, and further addition of 4.0% or more can obtain a remarkable effect. Therefore, from the viewpoint of obtaining excellent machinability,
Si is preferably 2.0 to 12.0 (not including 2.0)% or 4.0 to 12.0%. On the other hand, the upper limit of addition of Si must be 12.0% or less of the eutectic point in order to prevent deterioration of extrudability and embrittlement of the extruded material due to the formation of coarse primary crystal Si and increase in deformation resistance. 6% or less, which is particularly favorable for extrusion productivity.

Mg: 0.2 to 1.2% by mass Mg coexists with Si and becomes Mg ₂ Si during heat treatment to be precipitated and has the effect of increasing strength. If the Mg content is less than 0.2%, the effect cannot be obtained, while 1.2%
If it is added over the range, the solid solution strengthening of Mg alone increases the deformation resistance and reduces the extrudability. From the viewpoint of ensuring strength and good extrudability, it is preferably 0.4% or more and 1.0% or less, but from the viewpoint of exclusively suppressing deformation resistance during extrusion processing and improving extrudability. Less than 1%, especially 0.
If it is 9% or less, a remarkable effect can be obtained.
Therefore, in this case, Mg may be 0.2 to 1.0 (not including 1.0)% or 0.2 to 0.9%.

Cu: 0.15 to 3.0 mass% Cu enhances the strength by heat treatment and promotes chip breaking because it improves strain hardening ability. If the Cu content is less than 0.15%, the effect is poor, while if it is added over 3.0%, the corrosion resistance decreases and the extrudability also decreases. In particular, 0.2% or more and 2.5% or less are desired from the viewpoint of securing strength and good corrosion resistance and extrudability.

Cr: 0.04 to 0.35 mass% Cr has the effect of suppressing the strength reduction due to recrystallization during the process heat generation during extrusion, but if it is less than 0.04%, it has no effect. On the other hand, if added over 0.35%, Al-
A coarse Cr-based compound is generated to embrittle the extruded material. Especially from the viewpoint of preventing recrystallization and preventing embrittlement of the extruded material,
0.07% or more and 0.3% or less are desired.

Ti: 0.001 to 0.05 mass% Ti refines the cast structure and stabilizes the mechanical properties.
However, if the Ti content is less than 0.001%, the effect cannot be obtained, while if it is added over 0.05%, the refinement effect is not improved any more.

Fe: 0.5 to 1.0% by mass Zr: 0.1 to 0.5% by mass Fe and Zr form a compound with Al, respectively, and serve as a starting point for cutting chips to improve machinability. Therefore, it can be added if necessary. In the alloys of the present invention, the inclusion of less than the lower limit as unavoidable impurities is allowed,
If it is less than the lower limit, the effect is not sufficient, while if it exceeds the upper limit, a coarse compound is formed and the extrudability deteriorates.

As the inevitable impurities of the aluminum alloy, Pb, Bi and Sn are each 0.05 mass% or less and Mn in accordance with the chemical composition defined in JIS H4040.
Is allowed to be 0.15 mass% or less. If a large amount of these components is contained, the corrosion resistance (Pb, B
i, Sn) or machinability (Mn) is deteriorated, but within the above range, these characteristics are not affected.

[Invention of Claim 13] The aluminum alloy for alumite treatment according to the present invention specifies the use of the high corrosion-resistant aluminum alloy excellent in machinability described above. The finely dispersed Si and SiMg ₂ in the base material of this aluminum alloy do not interfere with the uniform formation of an oxide film, unlike Pb and Bi which are dispersed in conventional high machinability aluminum alloys, and have a uniform and glossy surface. It is possible to obtain a machine part or the like on which a certain alumite film is formed.

[0041]

EXAMPLES Examples of the present invention will be specifically described below in comparison with comparative examples. [Example 1] corresponds to the inventions of claims 1 to 5, [Example 2] corresponds to the inventions of claims 6 to 9, and [Example 3] is the inventions of claims 10 to 12. [Example 4] corresponds to the invention of claim 13.

[Example 1] An alloy having the chemical composition shown in Tables 1 to 3 was melted and an extruded billet having a diameter of 160 mm was prepared by semi-continuous casting. After homogenizing heat treatment at 520 ° C for 4 hours, 500 It was extruded to a diameter of 60 mm at an extrusion temperature of ° C.

[0043]

[Table 1]

[0044]

[Table 2]

[0045]

[Table 3]

From this extruded material, a test piece having a diameter of 20 mm and a height of 20 mm was taken in the extruding direction, cold-upset forged in the axial direction, and a critical upsetting ratio at which microcracks were generated on the side surface was obtained. The cold forgeability (upset forgeability) of each was evaluated in the following manner. Further, a test piece having a height of 60 mm was cut out from this extruded material, and cold upset forging was carried out in the axial direction (50% for those having a critical upsetting rate of 50% or more, 50% for the upsetting rate).
% Up to its limit upsetting ratio), and the upsetting forged materials were used to measure the mechanical properties, machinability and corrosion resistance of each in the following manner. In addition, in order to examine the extrudability, in the above extrusion, the extrusion load was kept constant (600 tons), the extrusion speed (speed when the extruded material came out) was measured, and the extrudability of each extruded material was evaluated in the following manner. .

Cold forgeability: ◎ (excellent) when the critical upsetting rate exceeds 50%, ◯ (usable) when 30 to 50%, × (not usable) when less than 30% It was evaluated. Mechanical properties: A tensile test piece having a diameter of 6 mm and a parallel portion length of 40 mm was taken from the upset forging material in a direction perpendicular to the upsetting direction, and its tensile strength, proof stress, and elongation were measured. Machinability: Using a commercially available high-speed steel 4 mm diameter drill, cutting under the conditions of a rotation speed of 1500 mm / min and a feed rate of 300 mm / min, and observing the occurrence of winding around the drill, as well as chip cutting property The weight per 100 chips was measured in order to investigate. Corrosion resistance: A 72-hour CASS test (adding 100 ppm of cupric chloride to 5% saline and spraying a solution adjusted to pH = 3 with acetic acid at 50 ° C.) to measure weight reduction per unit area . Extrudability: ◎ (excellent) when the value of the extrusion speed is greater than 5 m / min, ○ (useable) when the value is 2 to 5 m / min,
When it was less than 2 m / min, it was evaluated as x (not usable).

The results of these tests are shown in Tables 4 to 6. Alloys 1 to 32 corresponding to the examples of the present invention all showed excellent machinability and corrosion resistance, and this was confirmed to be alloy 45 of the comparative example.
(Equivalent to conventional 3003 alloy) or alloy 46 (conventional 30
(Equivalent to the 04 alloy), it is remarkably excellent in machinability, has the same mechanical properties and corrosion resistance, and has substantially the same cold forgeability. Further, the extruded material has no peeling or seizure marks and has a good surface property, and the value of extrudability is within a sufficiently usable range.

[0049]

[Table 4]

[0050]

[Table 5]

[0051]

[Table 6]

On the other hand, the alloys 33 to 47 of the comparative examples are alloys whose compositions are out of the range of the present invention, and some properties are inferior to those of the example alloys 1 to 32. That is, the alloys 33, 35, 37 and 39 are Si and M, respectively.
Since the contents of g, Cu, and Mn are insufficient, the machinability is inferior (the cutting ability of the cutting is inferior, and the cutting is wrapped around). Alloy 3
4, 36, 38, 40, 42 to 44 are Si,
Since Mg, Cu, Mn, Fe, Cr, and Zr are excessive, extrudability and cold forgeability are poor, and alloy 38 is also poor in corrosion resistance. Alloy 4
Since No. 1 does not contain an effective amount of Ti, the elongation is poor and the cold forgeability is poor. Further, the conventional alloys 45 and 46 are poor in machinability, and the alloy 47 made by adding Pb and Bi to the alloy 46 has improved machinability but poor corrosion resistance.

Example 2 An alloy having the chemical composition shown in Tables 7 and 8 was melted, and an extruded billet having a diameter of 160 mm was produced by semi-continuous casting. After homogenizing heat treatment at 520 ° C. for 4 hours, 500 It was extruded to a diameter of 60 mm at an extrusion temperature of ° C.

[0054]

[Table 7]

[0055]

[Table 8]

Test pieces were sampled from this extruded material in exactly the same manner as in [Example 1], and the cold forgeability, mechanical properties, machinability, corrosion resistance and extrudability were measured and evaluated in exactly the same manner. . The test results are shown in Tables 9 and 10. All of the alloys 48 to 60 corresponding to the examples of the present invention showed excellent machinability and corrosion resistance, and the alloys 69 (corresponding to the conventional 5056 alloy) and alloy 70 (conventional 5052) of the comparative example were shown.
Compared with alloy 71) and alloy 71 (corresponding to conventional 5083 alloy), they are remarkably excellent in machinability, have the same mechanical properties and corrosion resistance, and have almost the same cold forgeability. Further, the extruded material has no peeling or seizure marks and has a good surface property, and the value of extrudability is within a sufficiently usable range.

[0057]

[Table 9]

[0058]

[Table 10]

On the other hand, the alloys 61 to 72 of the comparative examples are alloys whose compositions are out of the range of the present invention, and some properties are inferior to those of the example alloys 48 to 60. That is, the alloys 62 and 64 are inferior in machinability due to insufficient contents of Si and Mg, respectively (inferior in chip cutting property and in wrapping of chips). Alloys 61, 63, 65 to 68 are inferior in extrudability and cold forgeability because Si, Mg, Cu, Fe, Cr and Zr are excessive, and alloy 65 is inferior in corrosion resistance. Further, the conventional alloy 69, alloy 70, and alloy 71 are inferior in machinability, and alloy 72 formed by adding Pb and Bi to alloy 69 is used.
Has improved machinability but poorer corrosion resistance.

Example 3 An alloy having the chemical composition shown in Table 11 and Table 12 was melted and an extruded billet having a diameter of 160 mm was produced by semi-continuous casting. After homogenizing heat treatment at 475 ° C. for 4 hours, 500 It was extruded to a diameter of 60 mm at an extrusion temperature of ° C, solution-treated at 520 ° C for 1 hour, and quenched in water. Further, artificial aging treatment was carried out at 170 ° C. for 6 hours to obtain a test material, and each mechanical property, machinability and corrosion resistance were measured and evaluated in the following manner.

[0061]

[Table 11]

[0062]

[Table 12]

Mechanical properties: JIS4 sampled in the extrusion direction
Tensile strength, proof stress, and elongation were measured using the No. test piece according to the metal material test method specified in JISZ2241. Machinability, corrosion resistance, extrudability; the same procedure as in [Example 1].

The results of these tests are shown in Tables 13 and 14. Alloys 73 to 98 corresponding to the examples of the present invention all exhibit excellent machinability and corrosion resistance, and when compared with Comparative Example Alloy 105 (corresponding to conventional AA6262 alloy), excellent corrosion resistance and even machinability Equal to or superior.
In addition, the extruded material has no peeling or seizure marks and has a good surface property, and the values of extrudability and mechanical properties are within the range where it can be sufficiently used.

[0065]

[Table 13]

[0066]

[Table 14]

On the other hand, the comparative alloys 99 to 105 are alloys whose compositions are out of the scope of the present invention, and some properties are inferior to those of the example alloys 73 to 98. That is, the alloys 100 and 101 are inferior in machinability due to a lack of Si amount (inferior in chip cutting property, and wrapping of chips),
Alloy 104 is inferior in corrosion resistance due to excessive Cu content.
No. 05 (corresponding to AA6262) contains Pb and Bi, so that the corrosion resistance is further deteriorated. Further, alloy 99 has an excessive amount of Si, alloy 102 has an excessive amount of Mg, alloy 103 has an excessive amount of Cr, and alloy 104 has an excessive amount of Cu.
Since the alloy 106 has an excessive amount of Fe and the alloy 107 has an excessive amount of Zr, the extrudability is poor.

Example 4 The surface of each of the test materials of Examples 1 to 3 was polished and then anodized with sulfuric acid to make the thickness of the oxide film 10 μm, and the surface gloss was observed. The case where the surface gloss was excellent was evaluated as ⊚, and the case where the surface gloss was inferior was evaluated as ×, and the results are also shown in Tables 4 to 6, 9, 10, 13, and 14.
The alloys corresponding to the examples of the present invention all have excellent surface gloss and excellent alumite processability.

[0069]

As described above, the aluminum alloy according to the present invention (claims 1 to 5) is not the conventional 3003 alloy or 3004 alloy even though it does not use a low melting point metal such as Pb or Bi. In comparison, it is a non-heat-treatable alloy with significantly superior machinability, mechanical properties, corrosion resistance, cold forgeability and extrudability that are almost the same. In addition, the aluminum alloy according to the present invention (claims 6 to 9) does not use a low melting point metal such as Pb or Bi, but has a conventional 505 content.
It is a non-heat treatment type alloy that has remarkably excellent machinability as compared with 6 alloy, 5052 alloy and 5083 alloy, and is almost the same in mechanical properties, corrosion resistance, cold forgeability and extrudability.
And, in both cases, troubles such as wrapping of chips on the tool due to long chips do not occur, and it is possible to achieve process cost reduction by adopting cold forging and omitting heat treatment, and also in recyclability Since there are no difficulties, it has a great industrial value.

On the other hand, the aluminum alloy according to the present invention (claims 10 to 12) is superior to the conventional AA6262 alloy in corrosion resistance and machinability. And since it does not cause troubles such as winding of chips around tools due to long chips, it is particularly suitable as a material for machine parts created by unmanned operation using automatic machine tools. Since it does not cause thermal embrittlement and has high recyclability, it has an extremely high industrial value as a highly corrosion-resistant aluminum alloy with excellent machinability that can be applied to various uses for which the AA6262 alloy was used. Further, since the aluminum alloy (claims 1 to 12) has improved machinability without adding Pb or Bi, it is possible to form a uniform and glossy alumite film having excellent alumite processability. .

Claims (13)

[Claims] 1. Si: 1.5 to 12.0 mass%, Mg:
0.5 to 6.0 mass%, Ti: 0.01 to 0.1 mass%
A highly corrosion-resistant aluminum alloy having excellent machinability, characterized in that each of them contains Al and the balance is Al and unavoidable impurities. 2. Si: 1.5 to 12.0 mass%, Mg:
0.5 to 1.0 (not including 1.0)% by mass, Ti: 0.
01-0.1% by mass respectively, and further Mn:
A highly corrosion-resistant aluminum alloy having excellent machinability, characterized by containing 0.5 to 2.0 mass% and the balance being Al and inevitable impurities. 3. Si: 2.0 to 12.0 (2.0 is not included) mass%, Mg: 0.5 to 6.0 mass%, Ti: 0.
01-0.1% by mass respectively, and further Mn:
A highly corrosion-resistant aluminum alloy having excellent machinability, characterized by containing 0.5 to 2.0 mass% and the balance being Al and inevitable impurities. 4. The high corrosion resistant aluminum alloy having excellent machinability according to claim 1, further comprising Cu: 0.1 to 1.0 mass%. 5. Further, Fe: 0.5 to 1.0% by mass,
Cr: 0.1 to 0.5% by mass, Zr: 0.1 to 0.5% by mass, and one or more of them are contained. Highly corrosion resistant aluminum alloy with excellent machinability. 6. Si: 1.5 to 12.0 mass%, Mg:
A highly corrosion-resistant aluminum alloy excellent in machinability, characterized in that it contains 2.0 to 6.0 mass% each, and the balance comprises Al and unavoidable impurities. 7. Si: 2 to 12.0 (not including 2) mass% and Mg: 2.0 to 6.0 mass% are respectively contained, and further Mn: 0.3 to 1.2 mass%. And the balance is A
A highly corrosion-resistant aluminum alloy having excellent machinability, which is characterized by comprising 1 and unavoidable impurities. 8. Further, Ti: 0.01 to 0.1% by mass.
A highly corrosion-resistant aluminum alloy having excellent machinability as set forth in claim 7, containing: 9. Further, Fe: 0.5 to 1.0% by mass,
9. Any one or more of Cr: 0.1 to 0.5 mass% and Zr: 0.1 to 0.5 mass% is contained, and it is described in any one of Claims 6 to 8. Highly corrosion resistant aluminum alloy with excellent machinability. 10. Si: 1.5 to 12.0 mass%, M
A highly corrosion-resistant aluminum alloy having excellent machinability, characterized in that g: 0.2 to 1.2 mass% and Cu: 0.15 to 3.0 mass% are respectively contained, and the balance comprises Al and unavoidable impurities. 11. The highly corrosion resistant aluminum alloy having excellent machinability according to claim 10, further containing Cr: 0.04 to 0.35 mass%. 12. Further, Ti: 0.001 to 0.05
% Or mass% is contained.
Highly corrosion resistant aluminum alloy with excellent machinability described in. 13. An aluminum alloy for alumite treatment, which has the chemical composition according to any one of claims 1 to 12.