JPH11217647A - 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 suitably used, e.g. for machine parts which require frequent application of machining in the course of manufacture. 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% 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 a machine part or the like which frequently uses a cutting process in a manufacturing process.

[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 Furthermore, when the alloy is recycled as scrap, it can be diverted to only a relatively small number of alloy types that require Pb, Bi, etc., which is disadvantageous in terms of recyclability because the diverted range is narrowed.

[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.

[0008] A non-heat-treated aluminum alloy having improved machinability without containing such a low melting point metal is disclosed in
Pb, B, although proposed in 184658
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. Generally speaking, an aluminum alloy excellent in both machinability and corrosion resistance is obtained, and a homogeneous alumite having recyclability is provided. An object of the present invention is to obtain an aluminum alloy which can form a film and has excellent machinability. More specifically, a non-heat treated type alloy having the same mechanical properties, cold forgeability, corrosion resistance, and recyclability as conventional 3000 type or 5000 type non-heat treated aluminum alloys, and improved machinability. An object of the present invention is to obtain an aluminum alloy, and to obtain a heat-treated aluminum alloy having machinability equal to or higher than that of a conventional AA6262 alloy and having improved corrosion resistance.

[0010]

Means for Solving the Problems The inventors of the present invention have made intensive studies to solve the above-mentioned problems, and as a result, low melting point metals such as Pb, Bi, Sn and the like which have been conventionally added for the purpose of improving machinability. Adds no Si and does not hinder recyclability
It has been found that the above object can be achieved by using Mg and Mg, and the present invention has been completed based on the knowledge. As described below, the present invention relates to two types of non-heat treatment type aluminum alloys having different strength levels (claims 1 to 5 and claims 6 to 9) and a heat treatment type aluminum alloy (claims 10 to 10). 12).

[Inventions of Claims 1 to 5] The highly corrosion-resistant aluminum alloy excellent in machinability according to the present invention is composed of Si: 1.
5 to 12.0% by mass, Mg: 0.5 to 6.0% by mass, T
i: 0.01 to 0.1% by mass, respectively, with the balance being Al and unavoidable impurities. In addition, the high corrosion-resistant aluminum alloy having excellent machinability according to the present invention may contain, as necessary, Mn: 0.5 to 2.0 mass% or Cu: 0.1 to 1.0 mass%, in addition to the above alloy elements. Or Fe: 0.5 to 1.0% by mass, Cr: 0.1 to 0.5% by mass, Zr: 0.1 to
It contains any one or more of 0.5% by mass, or contains any combination of the above elements.

The high corrosion-resistant aluminum alloy having excellent machinability has excellent strength and corrosion resistance as compared with the conventional 3003 alloy and 3004 alloy which cannot be applied to many mechanical parts due to poor forgeability but poor machinability. And a non-heat-treatable aluminum alloy having the same cold forgeability and markedly improved machinability, enabling low-cost cold forging and complex cutting. Further, the cutting ability of the chips is good, and troubles such as winding of the chips around the tool due to long chips are not generated. In addition, P
Since no low-melting-point metal such as b or Bi is added, it has high corrosion resistance, does not cause thermal embrittlement, and does not hinder recyclability. The aluminum alloy can be manufactured according to a conventional method. For example, after performing melting, casting, and homogenizing heat treatment, extrusion processing is performed, and the extruded material can be used as a material for forging processing.

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

Si: 1.5 to 12.0% by mass Si forms a Si-based compound in the aluminum structure, improves the cutting performance of the chips, and improves the cutting performance. This is because the Si-based compound serves as a starting point for cutting chips. It is necessary that the lower limit of Si addition exceeds 1.5%, which is the solid solubility limit in aluminum, and more than 2.0% is desirable in order to clarify the effect of Si. A remarkable effect can be obtained by adding 0.0% or more. Therefore, from the viewpoint of obtaining excellent machinability, S
i is preferably set to 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 is set so that coarse primary crystal Si is generated and deformation resistance is increased, so that extrudability is not reduced and extruded material is not embrittled.
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 an effect of improving the chip breaking property in order to improve the strain hardening ability, and has the effect of 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 (excluding 1.0)%,
Alternatively, it may be set to 0.5 to 0.9%.

Ti: 0.01-0.1% by mass Ti refines a cast structure and stabilizes 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% by mass Mn has the effect of forming a solid solution to increase the strength of the material, and has the effect of promoting chip breaking to improve 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% by mass Cu has the effect of forming a solid solution to increase the strength of the material and also promoting the cutting of chips 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%, the effect is poor.
If it is added in excess of 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 each represent a compound with Al. Forming
It serves as a starting point for cutting chips and improves cutting properties. In the present invention, the content of less than the lower limit as each inevitable impurity is allowed, but the effect is not sufficient below the lower limit,
On the other hand, if it exceeds the upper limit, a coarse compound is formed, and the extrudability decreases.

As the inevitable impurities of the aluminum alloy, Pb, Bi, and Sn are each allowed to be 0.05% by mass or less according to the chemical components specified 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 6 to 9] The highly corrosion-resistant aluminum alloy excellent in machinability according to the present invention is composed of Si: 1.
5 to 12.0% by mass, and Mg: 2.0 to 6.0% by mass, and the balance consists of Al and inevitable impurities.
In addition, the high corrosion-resistant aluminum alloy having excellent machinability according to the present invention may have M
n: 0.3 to 1.2% by mass, Ti: 0.01 to 0.1% by mass, or both.
e: 0.5 to 1.0% by mass, Cr: 0.1 to 0.5% by mass, Zr: 0.1 to 0.5% by mass. Both of the above elements are freely combined and contained.

The high corrosion-resistant aluminum alloy having excellent machinability has good cold workability, but has poor machinability, so that it cannot be applied to many mechanical parts and the like.
Compared to alloys and 5056 alloys, it is a non-heat treated aluminum alloy that has the same strength, corrosion resistance, and cold workability such as cold forging, and has significantly improved machinability. It is. Further, the cutting ability of the chips is good, and troubles such as winding of the chips around the tool due to long chips are not generated. In addition, Pb, Bi for improving machinability
Since no low-melting-point metal is added, it has high corrosion resistance, no thermal embrittlement can occur, and the recyclability is not hindered. In addition, this aluminum alloy can be manufactured according to a conventional method. For example, after performing melting, casting, and homogenizing heat treatment, extrusion processing is performed, and the extruded material can be used as a material for cutting.

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

Si: 1.5 to 12.0% by mass Si forms a Si-based compound in the aluminum structure, improves the cutting performance of the chips, and improves the cutting performance. This is because the Si-based compound serves as a starting point for dividing chips generated during cutting. It is necessary that the lower limit of Si addition exceeds 1.5%, which is the solid solubility limit in aluminum, and more than 2.0% is desirable in order to clarify the effect of Si. A remarkable effect can be obtained by adding 0.0% or more. Therefore, from the viewpoint of obtaining excellent machinability, the content of Si is preferably set to 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% by mass Mg has an effect of improving the chip breaking property to improve the strain hardening ability, and has the effect of 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%, deformation resistance increases and extrudability decreases. In particular, 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% by mass Ti refines a cast structure and stabilizes 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 material, and has the effect of promoting chip breaking to improve strain hardening ability. However, if the Mn content is less than 0.3%, a sufficient effect cannot be obtained, while if it exceeds 1.2%, the extrudability decreases. In particular, 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 each represent a compound with Al. Forming
It serves as a starting point for cutting chips and improves cutting properties. In the present invention, the content of less than the lower limit as each inevitable impurity is allowed, but if the content is less than the respective lower limit, the effect is not sufficient, while if the content exceeds the upper limit, a coarse compound is formed and the extrudability is reduced. I do.

As the inevitable impurities of the aluminum alloy, Pb, Bi, and Sn are each allowed to be 0.05% by mass or less in accordance with the chemical components specified 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] The highly corrosion-resistant aluminum alloy having excellent machinability according to the present invention comprises Si:
1.5 to 12.0 mass%, Mg: 0.2 to 1.2 mass%, Cu: 0.15 to 3.0 mass%, respectively.
The balance consists of Al and unavoidable impurities. In addition, the high corrosion-resistant aluminum alloy excellent in machinability according to the present invention may have Cr: 0.04 to
0.35% by mass or Ti: 0.001 to 0.05% by mass
One or both.

The greatest feature of the high corrosion-resistant aluminum alloy having excellent machinability is that Pb, B like AA6262 alloy.
That is, the machinability is improved without adding a low melting point metal such as i or Sn. This extruded aluminum alloy
Since no low-melting-point metal is added, it has higher corrosion resistance than AA6262 alloy, can not generate thermal embrittlement, and has high recyclability. Further, the cutting ability of the chips is good, and troubles such as winding of the chips around the tool due to long chips are not generated. In addition, the above-mentioned aluminum alloy is in accordance with an ordinary method,
For example, extrusion processing can be performed after melting, casting, and homogenizing treatments, and the extruded material can be 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 in the above aluminum alloy and the reason for limiting the amount of addition will be described.

Si: 1.5 to 12.0% by 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 becomes the starting point of strain propagation, and the propagation speed of strain received from the tool during cutting is increased. Therefore, the lower limit of Si addition is 1.5% which is the solid solubility limit in aluminum.
Must be exceeded, and in order to clarify the effect of Si, addition of more than 2.0% is desirable, and a remarkable effect can be obtained by adding more than 4.0%. Therefore, from the viewpoint of obtaining excellent machinability,
Si is preferably set to 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. It is particularly desirable that the extrusion productivity be 6% or less.

Mg: 0.2 to 1.2% by mass Mg coexists with Si to precipitate as Mg ₂ Si during heat treatment, and has the effect of increasing the strength. If the Mg content is less than 0.2%, the effect cannot be obtained, while 1.2%
If the addition exceeds the above range, deformation resistance increases due to solid solution strengthening of Mg alone, and extrudability decreases. From the viewpoint of ensuring strength and good extrudability, the content is preferably approximately 0.4% or more and 1.0% or less. However, from the viewpoint of exclusively suppressing deformation resistance during extrusion and improving extrudability. , Less than 1%, especially 0.
A remarkable effect can be obtained by setting the content to 9% or less.
Therefore, in that case, Mg may be set to 0.2 to 1.0 (excluding 1.0)% or 0.2 to 0.9%.

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

Cr: 0.04 to 0.35% by mass Cr has the effect of suppressing a decrease in strength due to recrystallization in the process of heat generation during extrusion, but has no effect if less than 0.04%. On the other hand, when adding over 0.35%, Al-
Generates a Cr-based coarse compound and embrittles the extruded material. In particular, 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% by mass Ti refines the cast structure and stabilizes mechanical properties.
However, if the Ti content is less than 0.001%, the effect cannot be obtained. On the other hand, if the Ti content exceeds 0.05%, the effect of miniaturization is not further improved.

Fe: 0.5 to 1.0% by mass Zr: 0.1 to 0.5% by mass Fe and Zr each form a compound with Al, and serve as a starting point of cutting chips to improve machinability. Can be added as needed. In the alloy of the present invention, the content of less than the lower limit as the inevitable impurities is allowed,
If the amount is less than the lower limit, the effect is not sufficient. On the other hand, if the amount exceeds the upper limit, a coarse compound is formed, and the extrudability decreases.

The unavoidable impurities of the above aluminum alloy are as follows: Pb, Bi and Sn are each 0.05% by mass or less, and Mn is Mn according to the chemical components specified in JIS H4040.
Is allowed to be 0.15% by mass or less. When these components are contained in a large amount, the corrosion resistance (Pb, B
i), Sn) or machinability (Mn) is deteriorated, but these properties are not affected within the above range.

[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 having excellent machinability described above. Si and SiMg ₂ finely dispersed in the base material of this aluminum alloy, unlike Pb and Bi dispersed in the conventional high machinability aluminum alloy, do not hinder the uniform formation of an oxide film and have a uniform and glossy surface. It is possible to obtain a mechanical part or the like on which a strong 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] corresponds to the inventions of claims 10 to 12. Embodiment 4 corresponds to the invention of claim 13.

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

[0043]

[Table 1]

[0044]

[Table 2]

[0045]

[Table 3]

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

Cold forgeability: When the critical upsetting ratio exceeds 50%, ◎ (excellent), when it is 30 to 50%, ○ (usable), and when it is less than 30%, × (not usable) Was evaluated. Mechanical properties: Tensile test specimens having a diameter of 6 mm and a parallel part length of 40 mm were sampled from the upsetting forged material in a direction perpendicular to the upsetting direction, and the tensile strength, proof stress, and elongation were measured. Machinability: Using a commercially available 4 mm diameter drill made of high-speed steel, cut at 1500 rpm / min and feed rate of 300 mm / min to observe the occurrence of wrapping around the drill, and to cut chips. The weight per 100 chips was measured in order to check the weight. Corrosion resistance: Weight loss per unit area was measured by a CASS test for 72 hours (a solution prepared by adding 100 ppm of cupric chloride to 5% saline and adjusting the pH to 3 with acetic acid at 50 ° C.). . Extrudability: when the value of the extrusion speed is more than 5 m / min, ◎ (excellent), when 2 to 5 m / min, ○ (usable),
When it was smaller than 2 m / min, it was evaluated as x (not usable).

Tables 4 to 6 show the test results. All of the alloys 1 to 32 corresponding to the examples of the present invention show excellent machinability and corrosion resistance.
(Equivalent to the conventional 3003 alloy) and alloy 46 (the conventional 303 alloy)
(Equivalent to alloy No. 04), it is remarkably superior in machinability, mechanical properties and corrosion resistance are the same, and cold forgeability is almost the same. Further, the extruded material had no surface peeling or seizure marks and had good surface properties, and the value of extrudability was 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 all have some characteristics inferior to those of the alloys of the examples. That is, alloys 33, 35, 37, and 39 are Si, M
Insufficient amounts of g, Cu, and Mn result in poor machinability (inferior chip cutting performance and wrapping of chips). Alloy 3
4, 36, 38, 40, 42 to 44 are each Si,
Excessive amounts of Mg, Cu, Mn, Fe, Cr, and Zr result in poor extrudability and cold forgeability, and alloy 38 also has poor corrosion resistance. Alloy 4
Since No. 1 does not contain an effective amount of Ti, elongation is poor and cold forgeability is inferior. Further, the conventional alloys 45 and 46 have poor machinability, and the alloy 47 obtained by adding Pb and Bi to the alloy 46 has improved machinability, but has poor corrosion resistance.

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

[0054]

[Table 7]

[0055]

[Table 8]

A test piece was sampled from this extruded material in exactly the same manner as in [Example 1], and cold forgeability, mechanical properties, machinability, corrosion resistance and extrudability were measured and evaluated in exactly the same manner. . Tables 9 and 10 show the test results. The alloys 48 to 60 corresponding to the examples of the present invention all show excellent machinability and corrosion resistance, which are compared with alloy 69 (corresponding to the conventional 5056 alloy) and alloy 70 (conventional 5052) of the comparative examples.
Compared with alloy (corresponding to alloy) 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 had no surface peeling or seizure marks and had good surface properties, and the value of extrudability was 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 all have some inferior properties to the alloys of the examples 48 to 60. That is, the alloys 62 and 64 are inferior in machinability due to insufficient contents of Si and Mg, respectively (inferior cutting ability of chips and winding of chips). Alloys 61, 63, 65-68 are inferior in extrudability and cold forgeability due to excessive amounts of Si, Mg, Cu, Fe, Cr and Zr, and alloy 65 is inferior in corrosion resistance. Conventional alloy 69, alloy 70 and alloy 71 are inferior in machinability, and alloy 72 obtained by adding Pb and Bi to alloy 69.
Has improved machinability but poor corrosion resistance.

Example 3 An alloy having a chemical composition shown in Tables 11 and 12 was melted, an extruded billet having a diameter of 160 mm was produced by semi-continuous casting, and subjected to a homogenizing heat treatment at 475 ° C. for 4 hours. It was extruded to a diameter of 60 mm at an extrusion temperature of 200 ° C., solution-treated at 520 ° C. for 1 hour, and quenched in water. Further, artificial aging treatment was performed at 170 ° C. for 6 hours to obtain test materials, and the mechanical properties, machinability and corrosion resistance of each test material were measured and evaluated in the following manner.

[0061]

[Table 11]

[0062]

[Table 12]

Mechanical properties: JIS4 sampled in the extrusion direction
The 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; same as in [Example 1].

Tables 13 and 14 show the test results. All of alloys 73 to 98 corresponding to the examples of the present invention show excellent machinability and corrosion resistance. Compared with comparative example alloy 105 (corresponding to conventional AA6262 alloy), alloys 73 to 98 have excellent corrosion resistance and machinability. Equal or better.
Further, the extruded material has no peeling or seizure marks and has good surface properties, and the values of extrudability and mechanical properties are within a sufficiently usable range.

[0065]

[Table 13]

[0066]

[Table 14]

On the other hand, the alloys of Comparative Examples 99 to 105 are alloys whose compositions are out of the range of the present invention, and all have inferior characteristics to those of the alloys of Examples 73 to 98. That is, the alloys 100 and 101 are inferior in machinability due to insufficient amount of Si (inferior in chip breaking and chip winding),
Alloy 104 is inferior in corrosion resistance due to an excessive amount of Cu.
05 (corresponding to AA6262) further 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.
The alloy 106 has an excessive amount of Fe, and the alloy 107 has an excessive amount of Zr.

[Example 4] The surfaces of the test materials of Examples 1 to 3 were polished, then anodized with sulfuric acid, the thickness of the oxide film was set to 10 µm, and the gloss of the surface was observed. Those with excellent surface gloss were evaluated as ◎, and those with inferior gloss were evaluated as x, and the results are shown in Tables 4 to 6, 9, 10, 13, and 14.
All of the alloys corresponding to the examples of the present invention have excellent surface gloss and excellent alumite treatment properties.

[0069]

As described above, the aluminum alloy according to the present invention (Claims 1 to 5) does not use a low melting point metal such as Pb, Bi, etc. This is a non-heat-treatable alloy that has remarkably excellent machinability and almost the same mechanical properties, corrosion resistance, cold forgeability, and extrudability. Further, the aluminum alloy (claims 6 to 9) according to the present invention uses the conventional 505 despite the fact that a low melting point metal such as Pb or Bi is not used.
This is a non-heat-treatable alloy that has remarkably excellent machinability as compared with Alloy No. 6, 5052 and 5083, and has almost the same mechanical properties, corrosion resistance, cold forgeability and extrudability.
In both cases, there is no trouble such as wrapping of chips around the tool due to long chips, and the cost can be reduced by adopting cold forging and omitting heat treatment. Since there is no difficulty, the industrial value is extremely large.

On the other hand, the aluminum alloy according to the present invention (claims 10 to 12) surpasses the conventional AA6262 alloy in corrosion resistance and machinability. Also, since there is no trouble such as wrapping 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. Therefore, AA6262 alloy has high industrial value as a highly corrosion-resistant aluminum alloy excellent in machinability which can be applied to various applications in which AA6262 alloy has been used. In addition, since the aluminum alloy (Claims 1 to 12) enhances the machinability without adding Pb or Bi, the aluminum alloy is excellent in alumite treatment property and can form a uniform and glossy alumite film. .

Claims (13)

[Claims] 1. Si: 1.5 to 12.0 mass%, Mg:
0.5 to 6.0% by mass, Ti: 0.01 to 0.1% by mass
, And the balance is made of Al and unavoidable impurities. A highly corrosion-resistant aluminum alloy having excellent machinability. 2. Si: 1.5 to 12.0 mass%, Mg:
0.5 to 1.0 (not including 1.0) mass%, Ti: 0.
0.01 to 0.1% by mass, and further contains Mn:
A highly corrosion-resistant aluminum alloy containing 0.5 to 2.0% by mass, with the balance being Al and unavoidable impurities. 3. Si: 2.0 to 12.0 (not including 2.0) mass%, Mg: 0.5 to 6.0 mass%, Ti: 0.
0.01 to 0.1% by mass, and further contains Mn:
A highly corrosion-resistant aluminum alloy containing 0.5 to 2.0% by mass, with the balance being Al and unavoidable impurities. 4. The highly corrosion-resistant aluminum alloy according to claim 1, further comprising 0.1 to 1.0% by mass of Cu. 5. Fe: 0.5 to 1.0% by mass,
The composition according to any one of claims 1 to 4, wherein the composition contains at least one of Cr: 0.1 to 0.5% by mass and Zr: 0.1 to 0.5% by mass. High corrosion resistance aluminum alloy with excellent machinability. 6. Si: 1.5 to 12.0 mass%, Mg:
A highly corrosion-resistant aluminum alloy excellent in machinability, containing 2.0 to 6.0% by mass, and the balance being Al and unavoidable impurities. 7. Si: 2 to 12.0 (not including 2) mass%, Mg: 2.0 to 6.0 mass%, and Mn: 0.3 to 1.2 mass%. And the balance is A
A highly corrosion-resistant aluminum alloy having excellent machinability, characterized by being composed of l and unavoidable impurities. 8. Further, Ti: 0.01 to 0.1% by mass.
The highly corrosion-resistant aluminum alloy having excellent machinability according to claim 7, wherein: 9. Further, Fe: 0.5 to 1.0% by mass,
The composition according to any one of claims 6 to 8, wherein one or more of Cr: 0.1 to 0.5% by mass and Zr: 0.1 to 0.5% by mass are contained. High corrosion resistance aluminum alloy with excellent machinability. 10. Si: 1.5 to 12.0 mass%, M
g: 0.2 to 1.2 mass%, Cu: 0.15 to 3.0 mass%, and the balance is made of Al and unavoidable impurities. 11. The highly corrosion-resistant aluminum alloy according to claim 10, further comprising 0.04 to 0.35% by mass of Cr. 12. Ti: 0.001 to 0.05
12. The composition according to claim 10, wherein the content is by mass.
High corrosion resistance aluminum alloy with excellent machinability described in. 13. An alumite-treating aluminum alloy having the chemical composition according to claim 1. Description: