JPS6022055B2 - Non-heat treated aluminum alloy for cutting and its manufacturing method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a non-heat-treatable aluminum alloy that has both excellent machinability and corrosion resistance, and a method for producing the same.

One of the most important properties required of aluminum alloys for cutting (hereinafter referred to as cutting) is chip control (
However, as automatic cutting machines have improved in recent years and ultra-high-speed cutting has become commonplace, the problem of tool wear has come into focus. In addition, precision cutting, high surface finish, and corrosion resistance are now required mainly for optical equipment, etc., and the demand for aluminum alloys for cutting tends to be of increasingly high quality.
Therefore, in order to meet these demands, there is an urgent need to develop an aluminum alloy that has both high cutting performance and corrosion resistance. By the way, as conventional aluminum alloys for cutting, American Aluminum Association AA2011 and AA62
Most of the alloys are heat treatable alloys such as No. 62, and these alloys are considerably superior in terms of scrap disposability.

However, it is insufficient in terms of corrosion resistance, especially the AA2011
Its corrosion resistance is extremely poor. Furthermore, since these alloys are heat-treated, they require extremely high-precision heat treatment equipment for solution treatment and aging treatment, and the residual stress that occurs when the water lining after solution treatment causes deformation during machining. Serious drawbacks have been pointed out, such as a decrease in dimensional accuracy.
On the other hand, it is known that low melting point metals such as Sn, Pb, Bi, Cd, and ln significantly improve the cutting properties of aluminum alloys.
It is also disclosed in Tokubatsu No. 57111/1983 that the machinability is improved by including 2Pb.

That is, the above-mentioned elements mutually form a eutectic in the aluminum alloy and are dispersed in the matrix, and it is believed that these elements are melted by the temperature rise during cutting, making it easier to break up chips. By the way, in aluminum alloy systems containing Mg, since Mg has a strong affinity with Pb, Sn, and Si, most of them form Mg-Si-Pb-Sn intermetallic compounds, and some M saddles Pb and M&Sn. Therefore, if the absolute amount of Pb or Sn is small, in an aluminum alloy system, the effect of improving machinability due to the eutectic of Pb and Sn cannot be expected, and other effects must be used to improve machinability. In order for chips to be finely divided, it is essential that the chips curl with a small curvature. sex does not improve.

The second necessary condition is that the curled scraps are easy to break when they collide with the tool or the material to be cut. The present inventors started developing an aluminum alloy that satisfies the above-mentioned conditions, and particularly investigated the effects of additive elements and microstructural factors on the chip curling characteristics and chip breaking properties of A-Mg alloys. Researched in detail.

As a result, (1) By dissolving Si in the A-Mg alloy matrix, the curling characteristics of chips are dramatically improved, resulting in chips with small curvature.

■ Mg-Si-Pb-Sn intermetallic compounds facilitate chip breakup, but it was confirmed that their size and number should be greater than a specified value in order to have a significant effect. .

In order to meet these requirements, the present invention was finally achieved as a result of repeated research on the blending ratio of additive elements and the size and number of Mg-Si-Pb-Sn intermetallic compounds in the alloy. That is, the non-heat-treated cutting aluminum alloy according to the present invention has a Mg content of 2.0 to 5.5% by weight.
%, Si 0.2-1.5%, Pb 0.3-1.5%
, Sn 0.3-1.5%, Cu 0.05-0.8%
The gist is that the remainder consists of A〆 and impurities, and the Mg-Si-Pb-Sn based intermetallic compound with a cross-sectional area of 2 or more is contained at least 10 per cross-section. .

Another aspect of the present invention relates to a method for industrially advantageously manufacturing the aluminum alloy of the above invention, in which an aluminum alloy ingot, which is cast with alloying elements in the range described above, is produced under specific conditions. The gist lies in the soaking process.

Furthermore, Mg-Si-Pb-Sn in the soaked product obtained above
In order to maintain the cross-sectional area and number of intermetallic compounds within appropriate ranges during subsequent extrusion processing and yuzu stretching processing, limitations are also placed on the extrusion conditions and yuzu stretching conditions. The reasons for specifying the blended elements, the size and number of intermetallic compounds, manufacturing conditions, etc. will be explained in detail below.

Mg is an essential element in order to increase the strength and corrosion resistance of aluminum alloys, and also to form intermetallic compounds with Pb, Si, and Sn, and its blending ratio with respect to the total amount of aluminum alloys is 2.0 to 5. .5% (weight%: hereinafter referred to as the same aircraft).

However, if it is less than 2.0%, the strength will be insufficient, and M
If the size and number of g-Si-Pb-Sn based intermetallic compounds are insufficient, the object of the present invention cannot be achieved, while if it exceeds 5.5%, extrusion processability deteriorates, which is not preferable. Si
is essential for improving the curling properties of chips, and must be added in an amount of at least 0.2% in order to exhibit this effect significantly.

The curling properties are improved as the amount of Si added increases, but when it exceeds 1.5%, coagulation and especially giant Mg2S
Since crystallization as i impairs tool life, it should be kept below this value. These effects can be further enhanced by adjusting the soaking treatment conditions during the manufacturing process to cause Si to settle into the substrate. Pb and Sn, together with Mg and Si, are used in Mg-Si-Pb-Sn intermetallic compounds and Mg2Sn.
, Mg2Pb is formed and dispersed in the matrix to facilitate the fragmentation of the components.

In order to exhibit these effects significantly, Pb and Sn
Each must be blended in an amount of 0.3% or more in the total aluminum alloy. However, if each exceeds 1.5%, although machinability improves, hot workability tends to decrease, so care must be taken. Most of the above Mg, Si, Pb and Sn exist as Mg-Si-Pb-Sn intermetallic compounds in the alloy matrix, and some exist as Mg2Pb and Mgbn. It is essential that the size is 2 or more in terms of cross-sectional area, and there must be 10 or more of these per cross-section when crossing a suitable part of the alloy. This is because even if the above-mentioned intermetallic compounds are formed in the aluminum alloy, if they are fine and have a cross-sectional area of less than 2 tsubo 2, they will not have a satisfactory effect of improving machinability. This is because the machinability cannot be significantly improved with less than ION hardness per fence. These requirements are one of the most important for the present invention, and the purpose of the present invention cannot be achieved by ignoring these requirements. However, even if some parts are less than ION hardness, the majority of the parts need only be ION hardness or higher, and this majority should normally be set at 90% of the entire cross section. Next, Cu is effective in enhancing the brightness of the aluminum alloy and further increasing its commercial value, and in order to ensure these effects, at least 0.05% or more is required.

However, if the content of Cu is too large, the corrosion resistance of the product tends to decrease, so it should be kept at 0.8 or less. In addition, the aluminum alloy of the present invention contains Fe, Mn, Cr, Zr, V, and Tj to the extent that they do not impede machinability.
, Ti-B, etc. may be included as impurities or may be actively blended.

That is, Fe, Mn, Cr, Zr, and V have the effect of further increasing the mechanical strength of the alloy, and each can be contained up to 0.4%. Further, Ti and Ti-B have the effect of refining crystal grains and increasing toughness, and can be contained up to 0.2%. However, care must be taken because too much of these elements will form insoluble intermetallic compounds in the aluminum alloy, impairing tool life.
Zn of 0.5% or less may also be added, but 0.5% or less of Zn may be added.
．． If it exceeds 5%, corrosion resistance will deteriorate. As described above, in the present invention, the types and proportions of elements to be mixed in the aluminum matrix are determined, and the Mn formed by these elements is
-It is characterized by specifying the size and distribution number of the Si-Pb-Sn intermetallic compound, but in order to ensure a unique metal structure like the latter, sufficient attention must be paid to the manufacturing method. Of course it should be.

The manufacturing process will be explained below. The coin coins made by mixing the above-mentioned types and amounts of elements into an aluminum substrate include Mg-Si-Pb-Sn of a certain size and number.
A system intermetallic compound is formed.

However, their size and number do not meet the requirements of the present invention, and in order to achieve the purpose of the present invention, it is necessary to subject the mirror blocks to some kind of post-processing. As a result of various studies on post-processing, the inventors found that 500 to 590 qo
It was confirmed that the purpose could be achieved by soaking for 2 to 2 hours. That is, by the above soaking treatment,
Si that has been crystallized in a eutectic state can be made to form a solid solution in the substrate, and Mg-Si-Pb-Sn intermetallic compounds can be aggregated and coarsened, and their size and number meet the above requirements. It can be done. If the soaking temperature is too low and too short, the above effects of the heat treatment will hardly be achieved. On the other hand, the higher the sintering temperature or the longer the sintering time, the greater the above effect, but if the soaking conditions are excessive, the crystal grains of the Mg-Si-Pb-Sn intermetallic compound become too coarse. Local melting causes ION solidification/
It becomes impossible to satisfy the requirement of 1 square or more. However, if the sintering conditions in the above range are adopted, the size and number of Mg-Si-Pb-Sn intermetallic compounds in the aluminum matrix can reliably meet the above requirements, and aluminum alloys with excellent machinability can be produced. You can get mirror blocks.
By the way, this coin coin can be used as it is as a base material for cutting, but it is often extruded and then cut.

However, depending on the extrusion processing conditions, the Mg-Si-Pb-Sn based intermetallic compound prepared by the soaking treatment may be finely destroyed during the extrusion process, which may deviate from the requirements of the present invention. Therefore, in the present invention, extrusion conditions are also taken into consideration, and certain limitations are attached to the extrusion conditions so that the size and number of Mg-Si-Pb-Sn intermetallic compounds do not deviate from the above-mentioned required range. . That is, when pressing, the following conditions should be adopted: temperature: 320 to 520°C, extrusion ratio: 75 or less. The same machine is also used when extruding extrudates, and the M
In order to prevent destruction of the g-Si-Pb-Sn based intermetallic compound, the processing rate must be 60% or less.

However, when the processing rate exceeds 60%, M
This is because the g-Sj-Pb-Sn based intermetallic compound is finely destroyed and the machinability is extremely deteriorated. In addition, there is no problem in carrying out quenching-tempering treatment, stabilization treatment, etc. of soaked materials, extrudates, or yuzu rolled products as necessary, as they have almost no negative effect on machinability. However, especially when performing stabilization treatment, for example 120~
It is desirable to use relatively mild conditions of about 0.5 to 6 hours at 28 mm.

The present invention is roughly configured as described above, and it specifies the types and amounts of elements to be mixed into an aluminum matrix, and also determines the size and size of Mg-Si-Pb-Sn intermetallic compounds formed by these elements. By identifying the number of
It has become possible to provide a non-heat-treated aluminum alloy for cutting that has excellent machinability and corrosion resistance.

Moreover, when manufacturing it, by specifying the soaking treatment conditions, extrusion processing conditions, and yuzu stretching processing conditions after casting,
This makes it possible to reliably obtain an aluminum alloy that meets the above requirements, and it is extremely useful as an aluminum alloy itself and as a method for producing the same. Next, examples will be given and explained, but the following are merely representative examples, and all modifications and implementations in accordance with the spirit of the preceding and following are included within the scope of the present invention.

Example 1 An aluminum alloy ingot containing the elements shown in Table 1 was cast by a semi-continuous casting method (diameter: 200 mm), and soaked at 560° C. for 4 hours.

Next, this was extruded at an extrusion ratio of 22.7 and a temperature of 400 mm (diameter: 42 ribs), and further subjected to yuzu stretching processing at a cold working rate of 18.1% (diameter: 38 ribs), resulting in a drawn product. Mechanical properties, machinability, corrosion resistance and Mg-Si-
The number of Pb-Sn based intermetallic compounds was measured. Second result
Shown in the table. Further, the drawn product obtained above was stabilized at 200° C. for 1 hour, and its mechanical properties, machinability, etc. were measured.

The results are shown in Table 3. However, the testing and measurement methods are as follows.

[1] Measurement of the size and number of Mg-Si-Pb-Sn intermetallic compounds: The extruded parallel section of the drawn product was mirror-polished, and 10 arbitrary points were examined using a quantitative television microscope at a magnification of 75 mm. Observe the Utsumi field and measure the number of intermetallic compounds with a cross-sectional area of 25 Buddha 2 or more.

The alloy of the present invention includes Mg-Si-Pb-Sn, M&
In addition to Sn-based and Mg2Nb-based compounds, Mg2Si and A
Although Fe is also included, these were confirmed in advance using an X-ray microanalyzer, and using the difference in contrast from the previous three, they were not counted using the contrast control of the quantitative television microscope. 0]
Cutting test: Cutting speed: 3 blood/min or 30 blood/min Feed: 0.04 pieces/rev or 0.12 shelves/rev Cutting depth: 2. Monoho cutting tool: Carbide bit, rake angle 10o Cutting oil: Usage evaluation: Based on visual judgment.

Reference photos A to C passed, D to E failed.] Tensile test: Using a JIS No. 4 test piece, the tensile speed was 3. Measured in shipboard/minute.

W] Corrosion resistance test: Observe the state after being immersed in a 3% NaC 202 aqueous solution for 48 hours.

The evaluation was done in four stages: A (almost no corrosion) to D (complete corrosion). Table 1 Chemical composition of sample gold (by weight) The remainder is A〃 and impurities Table 2 Performance of yuzu processed product Table 3 Performance of stabilized product Based on the results of Tables 2 and 3, the following facts are shown. is confirmed.

■ The higher the Si content, the better the machinability. Mg
In addition, Pb and Sn are also included, but if the Si content is small, the machinability deteriorates. ■ The greater the number of intermetallic compounds of 2 or more, the better the machinability becomes (M.6 has a large number of metal compounds, but the amount of Si is small, and this is absorbed by the intermetallic compounds, resulting in a small amount of Si alone. (The curling properties deteriorate, resulting in poor machinability).

■ In terms of strength, the alloys of the present invention (M.1 to 5)
is JIS5052 (no.7) and JIS5056 (no.
8) and passes the standard.

■ Regarding corrosion resistance, the alloy of the present invention has JIS50
Although it is slightly inferior to 52 and 5056, there is no problem in practical use.

■ The higher the Mg content, the better the machinability.

■ Stabilization treatment can further improve cutting performance on the high-speed feed side.

Example 2 In order to confirm the influence of soaking treatment conditions on the machinability of aluminum alloy, M. Two compositions of twill mass,
The machinability and the number of intermetallic compounds of 2 & 2 or more were measured without heat treatment and with heat treatment conditions of 400°C x 2 feeding times.

The results are shown in Table 4. As is clear from the results in Table 4, if soaking treatment is not performed or the heat treatment conditions deviate from the conditions of the present invention, the number of intermetallic compounds having a cross-sectional width of 25 mm2 or more is reduced. , good machinability cannot be obtained.

Example 3 In order to confirm the influence of extrusion ratio on the machinability of aluminum alloy, M. A coin coin (diameter: 40 mm) having the composition of Example 4 was subjected to soaking treatment under the same conditions as in Example 1, at a temperature of 350°C and an extrusion ratio of 90.2 (
42 ribs in diameter), and the machinability of the obtained product and the number of compounds with a size of 2 tsubo 2 or more were measured.

The results are shown in Table 5. Table 5 As is clear from the results in Table 5, when the extrusion ratio exceeds 75, intermetallic compounds of a predetermined size and number generated by the soaking process are finely destroyed during the extrusion process, resulting in poor machinability. It becomes something.

Example 4! - In order to confirm the influence of yuzu stretching conditions on the machinability of aluminum alloy, No. 1 in Table 1 was used. 1
After soaking a coin coin with the same composition under the same conditions, the temperature was 50.
The material extruded at 0°C and an extrusion ratio of 82 (diameter 7 m) was drawn at a cross-board processing rate of 70.5% (diameter 38 m), and the machinability and 2-gauge 2 or higher The number of intermetallic compounds was determined.

The results are shown in Table 6. Table 6 As is clear from the results in Table 6, even if a predetermined size and number of intermetallic compounds are present up to the extrusion process, if the processing rate during yuzu stretching is too high, the yuzu stretching process will be delayed. The intermetallic compounds are finely fractured, making it impossible to maintain excellent machinability.

Claims (1)

[Claims] 1% by weight: 2.0 to 5.5% Mg, 0.2 to 5.5% Si;
1.5%, Pb 0.3-1.5%, Sn 0.3-1
．． 5%, contains 0.05-0.8% Cu, and the balance is Al.
Mg-Si-Pb-S with a cross-sectional area of 25 μ^2 or more, which is an aluminum alloy for non-heat-treated cutting consisting of and impurities.
An aluminum alloy for non-heat-treated cutting, characterized by containing 100 or more n-type intermetallic compounds per 1 mm^2 of cross section. 2% by weight, Mg 20~5.5%, Si 0.2~
1.5%, Pb 0.3-1.5% Sn 0.3-1.
An aluminum alloy ingot containing 5% Cu, 0.05-0.8% Cu, and the remainder Al and impurities is made, and the ingot is soaked at 500-590°C for 2-24 hours to form a 25μ^
A method for producing a non-heat-treated aluminum alloy for cutting, characterized by forming 100 or more Mg-Si-Pb-Sn intermetallic compounds with a cross-sectional area of 2 or more per 1 mm^2 of a cross-section of an ingot. 3% by weight, Mg 2.0-5.5%, Si 0.2%
~1.5%, Pb 0.3~1.5%, Sn 0.3~
After making an aluminum alloy ingot containing 1.5% Cu, 0.005 to 0.8% Cu, and the balance consisting of Al and impurities, and soaking the ingot at 500 to 590°C for 2 to 25 hours. , Mg-Si- with a cross-sectional area of 25 μ^2 or more was extruded at an extrusion temperature of 320 to 520 °C and an extrusion ratio of 75 or less.
Pb-Sn intermetallic compound was extruded into a cross section of 1 mm^
A method for producing an aluminum alloy for non-heat-treated cutting, characterized by forming 100 or more pieces per 2 pieces. 4 Mg 2.0-5.5% and Si 0.2-5% by weight
1.5%, Pb 0.3-1.5%, Sn 0.3-1
．． An aluminum alloy ingot containing 5% Cu, 0.5 to 0.8% Cu, and the balance Al and impurities was made.
After soaking at 00 to 590°C for 2 to 24 hours, extrusion is carried out at an extrusion temperature of 320 to 520°C and an extrusion ratio of 75 or less, and the extrudate is drawn at a cold working rate of 60% or less to form a 25μ
A method for producing an aluminum alloy for non-heat-treated cutting, characterized by forming 100 or more Mg-Si-Pb-Sn intermetallic compounds having a cross-sectional area of ^2 or more per 1 mm^2 of a cross section of a drawn workpiece.