JP3690630B2 - Free-cutting aluminum alloy - Google Patents

Description

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【発明の効果】
本発明によるアルミニウム合金を用いて、押出形材を成形したものを評価した表３〜８に示す結果を比較すると明らかなように、Ｐｂ、Ｂｉを添加しなくてもＡＡ６２６２と同等の切削性を有し、ＡＡ２０１１よりも耐食性に優れる。
【図面の簡単な説明】
【図１】切削性評価に用いた刃具を示す。
【図２】
【図３】本発明合金による押出形材例を示す。
【図４】電位差腐食試験片の形状を示す。
【符号の説明】
１・・・アルミニウム合金押出形材
２・・・ダクロボルト[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an aluminum alloy having excellent machinability, and more particularly, to an aluminum extrusion molding having a hydraulic function such as a braking part for an automobile and used in a field requiring cutting. .
[0002]
In general, AA2011 alloy and AA6262 alloy are widely known as alloys used for the purpose of machinability.
[0003]
However, a large amount of Cu is added to the AA2011 alloy, which is inferior in corrosion resistance.
Further, low melting point metals such as Pb, Bi, and Sn are added to the AA6262 alloy, but these low melting point metals are hardly dissolved in aluminum and exist in a granular form in the aluminum alloy.
And it melt | dissolves with the process heat at the time of cutting, and cuts a chip, and improves machinability.
[0004]
For example, Japanese Patent Application Laid-Open No. 7-197165 discloses an alloy in which machinability is improved by adding a low melting point metal such as Pb, Sn, or Bi.
[0005]
[Problems to be solved by the invention]
Certainly, the effect of improving machinability can be seen by adding Pb, Bi, and Sn as in 6262 alloy.
[0006]
However, aluminum alloys containing these low-melting metals have the drawback of causing thermal embrittlement, and it is necessary to pay sufficient attention to the use conditions.
[0007]
Furthermore, since the aluminum alloy containing a low melting point metal contains Pb, Bi, etc., it also has a problem that it is disadvantageous for recyclability.
[0008]
In addition, in automobile control parts and the like, not only machinability but also pressure resistance strength potential difference corrosion resistance and the like are required, and further, material stickiness for caulking may be required for parts assembly. An aluminum alloy material that satisfies the required characteristics has been desired.
[0009]
[Means for Solving the Problems]
In the present invention, first, various components were added to aluminum, an extruded shape was formed by extrusion processing, and each quality characteristic and extrusion molding were extensively studied.
[0010]
As a result, the present invention has been achieved, and the means for solving the problem will be described together with the knowledge obtained by the experiment.
[0011]
There are various types of brake parts for automobiles, and anti-lock brake system actuator bodies, brake wheel cylinders, clutch master cylinders, proportioning valves, etc. are representative examples.
[0012]
The aluminum alloy used for these includes a cast material and an extruded material, and the present invention particularly relates to the extruded material.
[0013]
Free-cutting aluminum alloys such as AA6262 alloy have low melting point metals such as Pb, Bi, and Sn added for the purpose of improving machinability, but the present invention uses Si, Cu, Mn, etc. instead. It has been found that the above object can be achieved by blending, and the present invention has been completed based on the findings.
[0014]
That is, the aluminum alloy having excellent machinability related to the present invention is Si: 0.5 to 1.5 mass%, Cu: 0.4 to 0.2 mass%, Mn: 0.5 to 1.5 mass%. Mg: 0.5 to 1.5% by mass, with the balance being Al and inevitable impurities.
[0015]
Next, the reason for addition of each element in the aluminum alloy and the reason for limiting the addition amount will be described.
[0016]
By adding 0.5% or more of Si, precipitation of Mg ₂ Si is promoted, and the strength required for automobile braking parts is ensured.
[0017]
However, when Si is added in an amount of 1.5% or more, it exceeds the solid solubility limit in aluminum, so that a Si-based crystallized product is generated.
Thereby, there exists a fault by which the crack propagation speed at the time of material fracture | rupture is accelerated | stimulated.
[0018]
Adding 0.4% or more of Cu contributes to solid solution hardening in aluminum and also improves machinability.
[0019]
When emphasizing the machinability, 5.0% to 6.0% addition is good as in the case of AA2011 alloy, but if the amount of Cu is large, the anticorrosion property is lowered and the extrusion productivity is remarkably deteriorated.
In particular, when emphasizing the anticorrosion effect, it is necessary to suppress the addition to 2.0% or less.
[0020]
Therefore, ideally, Cu: 0.4 to 2.0 % is effective in achieving both the quality characteristics.
[0021]
When Mn is added in an amount of 0.1% or more, machinability and corrosion resistance can be improved, but if it is added in an amount of 1% or more, there is a drawback that intergranular corrosion is likely to occur.
[0022]
Ti has an effect of refining crystal grains and is added as necessary.
Similarly, when Ti is 0.01% or less, there is no effect of miniaturization, and when it is 0.1% or more, the effect is not only saturated but also the tool life during cutting is reduced.
[0023]
Fe: 0.1 to 1.0% has an effect of improving crystal grain refinement and machinability, but if it exceeds 1.0%, the effect is saturated. The effect is insufficient.
[0024]
【Example】
As shown in Tables 3 and 4, alloy NO. An alloy ingot having a composition of A to J was prepared.
This 8 inch φ ingot was homogenized at 420 to 500 ° C. for 6 hours or more, and then heated to 420 to 500 ° C. for hot extrusion.
[0025]
The extruded profile was a deformed profile shown in FIGS.
After the extruded profile is cut at 100 mm, the solution is kept at 500 to 560 ° C. for 2 to 5 hours, and then quenched at 30 to 60 ° C. for 10 minutes.
Then, the T6 process which hold | maintains artificial aging at 170-200 degreeC x 2 to 6 hours was performed.
[0026]
The extruded shape thus obtained was tested for extrudability, mechanical properties, corrosion resistance, and machinability by the following test methods.
[0027]
<Test method>
(1) Hot extrusion method The maximum extrusion speed that can be extruded without causing cracks on the surface of the extruded profile was measured, thereby evaluating the extrudability of each alloy.
The results are shown in Tables 5 and 6.
[0028]
(2) Mechanical properties Tensile test pieces corresponding to JIS No. 5 pieces were sampled from the extruded shapes treated with T6 and tested according to JIS Z2241.
The results are shown in Tables 5 and 6.
[0029]
(3) Corrosion resistance T6-treated extruded profile was processed as shown in FIG. 4 and assembled with dacro bolts on the threaded portion.
Evaluation was made by measuring the corrosion depth at and near the contact surface of the dacrobolt.
The results are shown in Tables 5 and 6.
[0030]
(4) Machinability T6-treated extruded shapes were punched under the conditions shown in Table 2 using the blade shown in FIG.
In the evaluation, the maximum chip length and the processed hole roughness were measured.
The results are shown in Tables 7 and 8.
[0031]
[Table 1]

[0032]
[Table 2]

[0033]
[Table 3]

[0034]
[Table 4]

[0035]
[Table 5]

[0036]
[Table 6]

[0037]
[Table 7]

[0038]
[Table 8]

[0039]
【The invention's effect】
As is apparent from comparison of the results shown in Tables 3 to 8 in which the extruded shapes were evaluated using the aluminum alloy according to the present invention, the machinability equivalent to that of AA6262 was obtained without adding Pb and Bi. And has better corrosion resistance than AA2011.
[Brief description of the drawings]
FIG. 1 shows a cutting tool used for machinability evaluation.
[Figure 2]
FIG. 3 shows an example of an extruded shape made of the alloy of the present invention.
FIG. 4 shows the shape of a potentiometric corrosion test piece.
[Explanation of symbols]
1 ... Aluminum alloy extrusion 2 ... Dacro bolt

Claims (2)

Si: 0.5 to 1.5 mass% (excluding 1.0 mass% or less) , Cu: 0.4 to 2.0 mass% (excluding 1.2 mass% or less) , Mn: 0.2 to An extruded aluminum alloy material having excellent corrosion resistance and machinability, having 1.0% by mass and Mg: 0.5 to 1.5% by mass, the balance being made of Al and inevitable impurities. Si: 0.5-1.5 mass%, Cu: 0.4-2.0 mass% (except 1.2 mass% or less) , Mn: 0.2-1.0 mass% (0.6 mass) %) And Mg: 0.5 to 1.5% by mass, respectively, and the balance is made of Al and inevitable impurities, and an aluminum alloy extruded shape having excellent corrosion resistance and machinability.

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