JP2001181770A - Aluminum-based alloy - Google Patents

Abstract

PROBLEM TO BE SOLVED: To produce a lead-free AlMgSi type aluminum alloy having the strength and cutting suitability as an automatically machining alloy, improved in production workability and wide in a machining temperature range in extrusion molding in particular. SOLUTION: The AlMgSi type aluminum-based alloy contains, as the main additive components, by weight, 0.6 to 2.0% magnesium(Mg), 0.6 to 3.0% silicon(Si), 0.6 to 1.5% tin (Sn) and 0.4 to 1.0% manganese(Mn), contains, as optional selective components, <=0.25% chromium(Cr) and <=0.1% titanium(Ti), contains, as a base body, aluminum and contains, as inevitable impurities, <=0.4% iron(Fe), <=0.1% copper(Cu) and <=0.2% zinc(Zn).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an AlMgSi type aluminum alloy suitable for high performance cutting.

[0002]

2. Description of the Related Art Aluminum alloys of this type meet extremely high requirements in terms of cutting workability, and are therefore used as high-performance working materials. Therefore, it is also called an automatically machined alloy. In the cutting of a work piece made of such an alloy, for example, in turning, milling or drilling, lead (P) having a content of 2% or more as an alloy component is obtained in order to obtain a desired cut piece.
b) has been added. However, when lead is added to obtain the required properties, this element's inherent health hazard, especially for workers involved in the processing of such materials, is disadvantageous. In addition, the lead component has a detrimental effect on the creep properties of aluminum alloys, which limits the use of this material and the products made therefrom at high temperatures.

[0003] Automatically machined alloys of this kind are known from Swiss Patent 239,996 and French Patent 977,514. The alloys described in these documents include tin (S) as a cutting promoting element in addition to lead.
n), bismuth (Bi), cadmium (Cd) or thallium (Tl), which may be used alone or in combination with lead, with their constituents in the alloy being 0.1%. It may be 3-4% by weight.
As is evident from the examples described in Swiss Patent 239,996, such alloys containing a substantial proportion of these elements have been used in practice. In the embodiment, the cutting acceleration component is 2% or more, that is, lead is used alone at a ratio of 2.56% by weight. The use of bismuth, cadmium or thallium other than lead is also not preferred. This is because some of these elements have a problem in environmental preservation or increase costs.

[0004] Copper (Cu), nickel (Ni) or zinc (Zn) is assumed as an alloy component used to improve the mechanical properties of the alloy. % By weight. When the content ratios of these alloy components in the above-mentioned technical level were measured on a large scale, in order to obtain the properties required for the alloys described in the above-mentioned documents, in fact, not less than a small amount of these elements were required and contained. It is clear that they must be. The same is shown in the examples described in those documents. However, in that case,
It is assumed that lead is in principle a very suitable element for achieving the required machinability.

To avoid the drawbacks associated with the use of lead, bismuth, cadmium or thallium, AlM
A gSi alloy has been proposed. In this alloy, tin is used in place of elemental lead in order to obtain characteristics required in terms of cutting suitability. Such alloys are described, for example, in US Pat.
No. 810952 or US Pat. No. 5,776,269.
It is described in the specification. As an additional constituent of these alloys, bismuth is used as an element for optimizing machinability, in addition to tin. Such Al without lead
In the case of MgSi alloy, in order to give sufficient strength, 0.3
Copper is added at a rate of .about.0.4% by weight. Even in the case of thermosetting alloys registered under the name of AA6020 with the Aluminum Association, copper is assumed as a major component for strength enhancement. The copper content can be between 0.3 and 0.9% by weight. The tin content of this alloy is between 0.9 and 1.5% by weight.

Even if, for example, Swiss Patent No. 239996 or French Patent No. 977514 can be interpreted literally, it can basically be read that tin can also be used alone as a cutting promoting component. Even so, such alloys were never actually made without the addition of other additives. This point is already evident from the examples given in these documents, and only aluminum alloys containing those containing other additives were produced.

[0007]

The strength achieved by the lead-free aluminum alloy is almost the same as that of the lead-containing type. However, the described lead-free type has drawbacks compared to previously known lead-containing types of high performance machined aluminum materials, which must be accepted. For example, in the processing of such an aluminum alloy, a drawback is that when extrusion molding is performed in a hot melt state by press heat, a relatively high temperature is required to perform the pressing step. Extrusion can be performed only in the temperature space between the required minimum temperature and the melting temperature. Therefore, if the required press temperature is high, the processing temperature space is limited to a very narrow range of 20 to 40 ° C.

For one thing, in such a narrow temperature space,
The problem is that it is difficult to comply with the parameters of the working process, and in part, in order to avoid the temperature space being exhausted by the additional heat of friction, and furthermore, the pressing tools used In order to avoid deformation or breakage due to overheating, the pressing process is
There is also the problem that it can only be done slowly. In the case of previously known auto-working alloys, the hot melt with press heat cannot be carried out in an economically acceptable manner for the reasons mentioned above.

[0009] Therefore, the extruded product is subjected to an ablation heat treatment through an additional step in order to obtain desired material properties. Only formations or formation fragments having a structural length less than a certain limit can be used in such ablation furnaces. The length of these pieces is significantly shorter than the formations made by the extrusion process. Nevertheless, in most cases, the ablation heat deforms the object, and in some cases, the object is unacceptably repelled. Therefore, in that case, it is necessary to pass through a separate working process after the ablation heat treatment. However, an object having a length of about 50 cm can no longer be used.

Accordingly, the present invention is based on the above-mentioned state of the art, and has the strength and cutting suitability of a previously known automatic work alloy, and has an improved manufacturing workability, particularly in a processing temperature space in extrusion molding. Large, AlMgSi
The task is to produce a type of lead-free aluminum alloy.

[0011]

The object of the present invention is to provide, according to the present invention, -0.6 to 2.0% by weight of magnesium (Mg) -0.6 to 3.0% by weight of silicon ( Si)-0.6 to 1.5% by weight of tin (Sn)-0.4 to 1.0% by weight of manganese (Mn); optionally up to 0.25% by weight of chromium (Cr) each; 0.1% by weight of titanium (Ti) and aluminum (Al) as a matrix, and other inevitable impurities up to 0.4% by weight of iron (Fe), up to 0.1% by weight of copper (Cu), It is solved by an AlMgSi type aluminum-based alloy containing up to 0.2% by weight of zinc (Zn).

According to the invention, it contains the same and possibly improved cutting properties, even though it contains only very small amounts, ie only 0.6 to 1.5% by weight, of cutting promoting elements. In addition, an aluminum-based alloy is created that contains only one element as a cutting-promoting element (unlike the previously known types in which elements other than this element are always added). Even if tin is used as the only strong cutting promoting element, there is no problem in terms of environmental conservation. Since several types of cutting-promoting elements were contained in a relatively large ratio in the previously known automatic machining alloys, the present invention in which the use ratio of the used elements was defined in a narrow range was determined at this technical level. It was not expected that alloys based on Pb would have such effective cutting properties. Thus, in the case of the aluminum-based alloy claimed in the present invention, it is not necessary to mix lead, bismuth or other heavy metals used in the previously known automatic working alloy. The parties involved in the present invention have found that, within the range of elemental usages specified in the claims, a phase is formed which greatly improves the machinability of the working material made from the alloy. To do so, the inventor needed to be liberated first of all, rather than being held to the dominant theory.

To impart the required strength to the aluminum alloy, tin is used in addition to the constituent components magnesium, silicon and manganese. In aluminum-based alloys according to the invention, the use of bismuth and / or indium is not as necessary as copper in achieving the required strength. The alloy may also contain a small percentage of chrome as an optional component. This additional component also has a favorable effect on the strength and cutting suitability of the aluminum-based alloy within the range of the usage ratio stated in the claim. On the contrary, if its content increases, the properties of the alloy are impaired. To refine the alloy material, 0.1% titanium is added.
It can be added in a proportion of up to weight%. The titanium content is preferably set to 0.02 to 0.08% by weight.

The aluminum-based alloy according to the present invention has a much larger working temperature range in extrusion molding than the previously known aluminum-based alloy, so that the incineration melting process can be performed by press heat. This property can never be found anywhere in the prior art. In particular, it was not anticipated within the state of the art that the alloys could be processed at low pressing temperatures, but this would avoid the disadvantages of the subsequent burning process. In the case of the alloy according to the invention, the hot melt treatment can be carried out by press heat, so that the work material produced by extrusion can be rolled as it is in its full width and, as in the known state of the art, heat It is not necessary to divide it into a size suitable for the furnace. As a result, the number of stretched materials that are not available in the method for producing the alloy according to the invention is considerably reduced.

In the case of aluminum-based alloys according to the invention, the pressing temperatures required for carrying out the extrusion process are considerably lower than those required for previously known copper-containing aluminum-based alloys. The required pressing temperature is copper containing AlMgS
The temperature can be lowered by about 30 to 50 ° C. as compared with the case of the i-alloy. As a result, the working temperature range is widened, so that not only the melting treatment by press heat can be performed in a wider temperature range, but also the extrusion and quenching time can be rapidly extended. This advantage is remarkable even in the case of forging or rolling of a work material made of such an aluminum-based alloy. In addition, the claimed aluminum-based alloy has better corrosion resistance than the previously known state of the art.

By using the selected element in the weight ratio described in the claim, not only the cutting suitability and strength characteristics are excellent, but also the processing suitability in extrusion molding is improved.
Very good aluminum-based alloys of the AlMgSi type were obtained. In particular, the fact that copper was not intentionally incorporated as an alloy component, but was excluded from its constituent components in the direction of allowing it only as an impurity component, has led to the production of extruded products by melting treatment with press heat and tempering. Making it possible. As a result, it is possible to obtain an automatically machined alloy that is very economical in terms of both production and processing.

However, iron, copper, and zinc are inevitable impurity components, but up to a certain ratio in the alloy has no effect on the alloy characteristics and is acceptable. However, if it exceeds the allowable range, the desired alloy characteristics will be impaired,
However, these elements need not be constituents of the alloy.

The maximum content of each of the other unavoidable impurity element components in the aluminum-based alloy must not exceed 0.05% by weight. Otherwise, the desired alloy properties may be affected. The claimed aluminum-based alloy is particularly useful for processing products by extrusion, due to its advantages.

In a typical embodiment of an aluminum-based alloy, the following are included as main additives: 1.0-1.2% by weight magnesium -0.8-1.0% by weight Silicon-0.9 to 1.1 wt% tin-0.6 to 0.8 wt% manganese In this aluminum-based alloy, the chromium content should not exceed 0.1 wt%.

The composition is:-1.1% by weight magnesium-0.95% by weight silicon-1.1% by weight tin-0.65% by weight manganese-0.19% by weight iron-balance aluminum The working temperature range and the tensile strength of extruded aluminum of not more than 0.05% by weight in all other elements were measured on two samples. A block mold (sample 1) having a diameter of 360 mm extruded and cast from this aluminum alloy is homogenized in the first step after casting, and is subsequently formed in a molding step at a block mold temperature of 510 to 520 ° C. at 30 to 60 ° C.
It was pressed into moldings of various wall thicknesses of 5 mm. The melting heat treatment of this alloy was performed in a pressing step. After the press working, the formed product was exposed to air and cooled to a temperature of 470 ° C., and then quenched with water for the first time. The composition so treated was adjusted to a maximum hardness at 170 ° C. without intermediate fusion treatment as was done in the prior art, followed by a tensile test for typical strength and ductility. . Those formations, according to the measurement of the longitudinal direction, elongation at failure A ₅ to 10%
And the 0.2% yield point _Rp0.2 at that time is 345 Mpa
And a tensile strength _{R m} is excellent in 367Mpa. After casting a second sample of the same alloy and the same block type, homogenize at a block temperature of 530 to 540 ° C, and at least 530 to 54
Pressing was performed at a temperature of 0 ° C., and immediately thereafter, it was quenched with water. Also in the case of this sample, the melting process was automatically performed by the heat applied during the press working. Subsequently, this product was also adjusted to the highest hardness at 170 ° C.
According to measurements, this sample has a 0.2% yield point R
_p0.2 is 348Mpa, tensile strength _{R m} is 371Mpa
And breaking elongation _{A 5} is resulted in 10%. The following table summarizes the test results in comparison to previously known aluminum-based alloys:

[0021]

[Table 1]

Despite different processing steps, both formations made from the samples (Sample 1, Sample 2) have approximately the same strength and ductility properties. Furthermore, as is clear from the above table, the maximum strength of the copper-containing aluminum-based alloy cannot be attained without additional fusion heat treatment. Furthermore, as can be seen from the results when using a previously known technique, the strength after the melting treatment by press heat is:
It depends on the extrusion temperature. As a result, temperature fluctuations during extrusion are reflected in the strength of the resulting product, but this is not preferred.
Such a defect in the alloying process can be avoided only by passing through a separate heat treatment process, but it involves inconvenience (see above). As described above, the results of the test indicate that the aluminum-based alloy according to the present invention (for example, in extrusion molding) has a wider range of processing conditions if the strength and ductility are the same as those of the conventional method. It is much larger and results are improved.

The following table summarizes the differences in cutting suitability of various AlMgSi alloys. In the last column of the table, the cutting properties of the alloy according to the invention, that is to say the work pieces consisting of samples 1 and 2, are shown in comparison with previously known alloys.
Some of the data listed in the tables are taken from the material description, but the rating class is based on the same system as applied to other alloys.

[0024]

[Table 2]

[0025]

The alloys "Stanal 32", "AA"
It should be noted that "6020" and "KA62" were made based on the so-called T6 method and the separate melt heat treatment included therein. Other alloys are made based on the T5 method involving a melting treatment by press heat. As is evident from the above table, the cutting properties of the work pieces made of the alloy according to the invention are excellent, comparable to the corresponding values of work pieces previously obtained only with lead-containing AlMgSi alloys. In addition to the above,
In the case of a copper-containing AlMgSi alloy material, it is particularly important that the work piece made of the alloy according to the present invention is subjected to a separate heat treatment step before the thermosetting step so as to have at least partially the same cutting properties. I will add it.

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Claims (11)

[Claims] 1. As main components: 0.6 to 2.0% by weight of magnesium (Mg); 0.6 to 3.0% by weight of silicon (Si); 0.6 to 1.5% by weight. Tin (Sn)-0.4 to 1.0 wt% manganese (Mn), optionally up to 0.25 wt% chromium (Cr), 0.1 wt% titanium (Ti) and It contains aluminum (Al) as a base, and other inevitable impurities include iron (Fe) up to 0.4% by weight, copper (Cu) up to 0.1% by weight, and zinc (Zn) up to 0.2% by weight. ), Characterized by containing
Type aluminum alloy. 2. The aluminum alloy according to claim 1, wherein the unavoidable impurity element components do not exceed 0.05% by weight at most. 3. The aluminum alloy according to claim 1, wherein the magnesium component is 1.0 to 1.2% by weight. 4. The aluminum alloy according to claim 1, wherein the silicon component is 0.8 to 1.0% by weight. 5. The aluminum alloy according to claim 1, wherein the tin component is 0.9 to 1.1% by weight. 6. A manganese component comprising 0.6 to 0.8% by weight.
The aluminum alloy according to claim 1 or 2, wherein 7. Aluminum alloy according to claim 1, wherein the chromium component is at most 0.1% by weight. 8. The method of using an AlMgSi type aluminum alloy according to claim 1, for the purpose of producing an extruded product. 9. The method according to claim 8, wherein the product extruded in the extrusion process is directly quenched in an outlet region of the equipment. 10. An extruding process in which a melting treatment is performed by press heat, an extruding object is quenched after leaving an extruder, and the extruding object is thereafter passed through a thermosetting process. An AlMg according to any one of claims 1 to 7, characterized in that:
A method for producing an extrusion-formed object made of a Si-type aluminum alloy. 11. Before the object exits the press machine and enters the quenching process, the object is first exposed to air to about 460-4.
The method according to claim 10, wherein the method is cooled to a temperature of 85 ° C.