JPH06258314A - Strength-characteristic index diagram of aluminum alloy and alloy-component setting method of aluminum alloy by using it - Google Patents

Abstract

PURPOSE:To estimate the strength characteristic of an aluminm alloy and to set kinds and amounts to be added of chemical elements for the aluminum alloy so as to obtain a desired characteristic by using a strength-characteristic index diagram which indicates the relationship between the strength characteristic of the aluminum alloy as a parameter for a <MK> and the <MK>. CONSTITUTION:For example, the relationship between the tensile strength in an annealed state of a non-heat-treatment-type aluminum alloy for rolling and an <MK> is indicated according to it, a quantitative relationship is recognized between the <MK> and the tensile strength irrespective of an alloy system, and, the larger the <MK> of the alloy is, the larger a strength characteristic is. The quantitative relationship is expressed by a function formula of strength characteristic=(a)+(b)X<MK>, where (a) and (b) are constants. This indicates that the <MK> is an important parameter to evaluate the strength characteristic of the non-heat-treatment-type aluminum alloy. When such a strength-characteristic index diagram is used, the strength characteristic can be estimated on the basis of the composition of an alloy without making a complicated experiment.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an alloy strength characteristic index chart used for evaluation of various alloy characteristics and quality control of an aluminum alloy. Further, the present invention develops and manufactures an aluminum alloy using the strength characteristic index chart. In this case, the present invention relates to a method of determining the composition and amount of the additive element for alloy and setting the alloy composition.

[0002]

2. Description of the Related Art Aluminum is widely used as a structural member for aircraft or automobiles because it has characteristics such as high specific strength and excellent corrosion resistance. In that case, the kind and addition amount of the required alloying element are determined by combining various characteristics. Therefore, conventionally, an aluminum alloy having desired characteristics has been developed by adding various alloy elements to aluminum. Regarding the development of this conventional aluminum alloy and the management of various properties, the effect of alloying elements on the property or properties of the aluminum alloy is determined from experiments and the optimum alloy composition is determined based on these data. Trial and error methods are routinely practiced.

[0003]

However, according to the conventional trial-and-error method, the development of an alloy having various properties requires a great deal of cost and time, is extremely inefficient, and is particularly inefficient. It is extremely difficult to carry out such a method for an unproven multi-component alloy. Further, in the case of this trial-and-error method, the evaluation is also inaccurate, which is a big problem in terms of improving the reliability of the material and improving the performance.

The present invention has been made in order to solve the above-mentioned conventional problems. First, a strength characteristic index chart is obtained, the strength characteristics of the alloy are predicted based on this, and then the alloy in a limited range. To provide an aluminum alloy strength characteristic index diagram and alloy component setting method that enables development of an aluminum alloy having both strength and other characteristics, and greatly reduces investment for research and development, by conducting experiments only on It is an object.

[0005]

[Means for Solving the Problems] As a result of various studies to solve the above problems, the present inventors have evaluated the various properties of aluminum alloys by analyzing the electronic structure of aluminum alloys by the molecular orbital method [Discrete Variation (DV)]. -Xα cluster method]. S of the alloying element M in the mother metal aluminum, which is the parameter obtained from this calculation
By using the orbital energy level (hereinafter referred to as Mk), it has been found that a strength characteristic index diagram of the aluminum alloy can be obtained, and various characteristics of the aluminum alloy can be evaluated by this.

The present invention is based on the above findings,
<Mk> or <ΔMk> of the alloy is calculated by Equation 1 or Equation 2, and the strength characteristics of the aluminum alloy and <Mk> or <ΔMk> are defined with <Mk> or <ΔMk> thus defined as a parameter. The present invention relates to a strength characteristic index diagram of an aluminum alloy characterized by showing the relationship of

[0007]

## EQU1 ## <Mk> = ΣX _i (Mk) _i where: X _i is the atomic fraction in the alloy of element i; (Mk) _i is the Mk value of element i.

[0008]

<ΔMk> = ΣX _i | (ΔMk) _i | where: X _i is the atomic fraction of the alloy of element i; (ΔMk) _i = (Mk) _i − (Mk) _Al ; (Mk) _i Is the Mk value of element i; (Mk) _Al is the Mk value of pure aluminum.

The present invention also relates to a method for setting the composition of an aluminum alloy, characterized in that the kind and addition amount of the alloying element are determined so as to obtain desired characteristics by using the strength characteristic index diagram of the aluminum alloy. is there.

The DV-Xα cluster method is a molecular orbital calculation method which is carried out by using an aggregate model of several to several tens of atoms. This calculation method is described in detail in, for example, "Introduction to Quantum Material Chemistry" by Hirohiko Adachi (Sankyo Publishing, 1991).

FIG. 1 shows the MAl ₁₈ cluster model used by the present inventors in the above calculation. However, in the figure, ○ indicates aluminum (Al), and ● indicates alloying element (M). Figure 1 above
At, the interatomic distance is set from the lattice constant, and the electronic structure of the cluster (molecule) is solved self-consistently using the Xα potential proposed by Slater. However, unlike the usual method, when solving the secular equation, the Hamiltonian and the matrix element of the overlap integral are calculated at randomly selected sample points in the space, and the energy eigenvalues and eigenfunctions of the electrons are calculated (for details, see "Quantum Material" above). See "Introduction to Chemistry").

Unlike the band calculation method, this cluster method is suitable for examining local electronic states. By investigating the electronic states around the alloy elements using the cluster model of FIG. 1, a parameter expressing the alloy effect, that is, M
k can be obtained. The s orbit in the aluminum alloy is spread over a wide energy range, and among them, the energy level of a _1g at which the s orbital occupation ratio is relatively high is represented as Mk. Table 1 shows the cluster model MAl ₁₈ of FIG.
The parameter Mk for each alloying element M obtained as a result of the calculation using is shown (unit is eV. However, for simplicity, the following unit is omitted). In the multi-component alloy, the average value of Mk and the average value of the absolute values of the differences between the Mk of the alloy element M and the Mk of pure aluminum are shown by the composition averages as in the above-mentioned Formula 1 and Formula 2 respectively.

[0013]

[Table 1]

[0014]

EXAMPLES Examples of the present invention will be specifically described below. [Example 1] Evaluation of strength characteristics of a non-heat treatment type wrought aluminum alloy by <Mk>. In this example, the relationship between the strength characteristics of a non-heat treatment type wrought aluminum alloy and <Mk> was investigated. The strength properties and alloy compositions of known alloys are extracted from the standard mechanical properties and alloy standard compositions of Metals Handbook (ASM, 9th edition, Vol. 2) and Aluminum Handbook (Light Metal Institute, 3rd edition). In addition, the amount of alloying element for calculating <Mk> used an intermediate value for the alloying element and an upper limit value for the impurity element within the standard composition range.

FIGS. 2 and 3 show the relationship between <Mk> and the tensile strength and 0.2% proof stress in the annealed state of a non-heat treatment type wrought aluminum alloy. 2 and 3
As is clear from the above, a quantitative relationship was observed between <Mk> and tensile strength and 0.2% proof stress regardless of the alloy system. I found it big. 4 and 5 show tensile strength, 0.2% proof stress and <Mk> of the non-heat treatment type wrought aluminum alloy (Hn4 material and Hn8 material) which has been cold worked according to JIS standard. Shows the relationship. 4 and 5
Therefore, in the cold-worked material as well as the annealed material (O material), regardless of the alloy system, <Mk>, tensile strength and 0.2
A quantitative relationship was found between the% yield strength, and it became clear that the larger <Mk> is, the better both strength characteristics are.

The quantitative relationship between <Mk> and the strength characteristics of the non-heat treatment type wrought aluminum alloy as described above is as shown in FIG. 6, FIG. 7 and FIG. It was also found to be true between the strength and the fatigue strength.

Furthermore, the tensile strength at low temperature (77K) and the 0.2% proof stress and <Mk> are also shown in FIG.
And, as shown in FIG. 10, the same quantitative relationship as above is established.

The quantitative relationship between them is expressed by a functional expression such as equation (3). However, a and b are constants. Table 2 shows constants a and b with respect to typical strength characteristics of the non-heat treatment type aluminum alloy obtained by the least square method, and the correlation coefficient between various strength characteristics and <Mk>. From these, it can be seen that <Mk> is an important parameter for evaluating the strength characteristics of the non-heat treatment type aluminum alloy. Furthermore, by using such a strength characteristic index chart, it is possible to predict the strength characteristics from the alloy composition without performing a complicated experiment.

[0019]

## EQU3 ## Strength characteristic = a + b × <Mk>

[0020]

[Table 2] The symbol O is annealed, H8 is 75% cold-worked, and H4 is cold-worked to have an intermediate tensile strength between O and H8.

Example 2 Evaluation of strength characteristics of a heat treatment type wrought aluminum alloy by <ΔMk>. In this embodiment, a heat treatment type wrought aluminum alloy,
The relationship between the strength characteristics in the heat treatment state and <ΔMk> was investigated. The strength characteristics and alloy composition of known alloys are
ls Handbook (published by ASM, 9th edition, Vol.2) and Aluminum Handbook (published by Japan Institute of Light Metals, No. 3)
It is extracted from the standard mechanical properties and standard composition of the edition). The amount of alloying elements used to calculate <ΔMk> was an intermediate value for alloying elements and an upper limit value for impurity elements within the standard composition range.

FIG. 11 and FIG. 12 are tensile tests of a heat-treatable aluminum alloy that is naturally aged after quenching (hereinafter referred to as T4) and a heat-treatable aluminum alloy that is artificially aged after quenching (hereinafter referred to as T6) based on JIS standards. The relationship between strength and <ΔMk> is shown. As is clear from FIGS. 11 and 12, a quantitative relationship was observed between <ΔMk> and tensile strength, and it was found that the alloy having a larger <ΔMk> has a larger tensile strength. Furthermore, the present inventors
3, As shown in FIG. 14, FIG. 15, FIG. 16, FIG. 17, and FIG. 18, other strength characteristics of the heat-treatment type wrought aluminum alloy (0.2% proof stress, Brinell hardness, shear strength, fatigue strength) And tensile strength at 77K and 0.
It has been confirmed that there is a similar quantitative relationship between the above (2% proof stress) and <ΔMk>. The relationship between them is represented by a functional expression such as Equation 4. However, a and b are constants. Table 3 shows the constants a and b for various strength characteristics of the heat treatment type aluminum alloy obtained by the least square method, and the correlation coefficient between the various strength characteristics and <ΔMk>.

[0023]

## EQU4 ## Strength characteristic = a + b × <ΔMk>

[0024]

[Table 3] Temporal symbol T4 is T6 after natural aging after solution treatment
Indicates the one that was artificially aged after the solution treatment.

From the above, it can be seen that <ΔMk> is an important parameter for evaluating the strength characteristics of the heat treatment type aluminum alloy. Furthermore, by using such a strength characteristic index chart, it is possible to predict the strength characteristics from the alloy composition without conducting a complicated experiment.

Example 3 Evaluation of initial extrusion load of Al-Mg-Si alloy by <Mk>. FIG. 19 shows Al-0.52% Mg-0.46% Si-0.
The initial extrusion load and <Mk> of a total of 7 kinds of Al-Mg-Si based alloys having a basic composition of 15% Fe alloy and added with 0%, 0.1% and 0.3% of Cr, Mn and Cu, respectively. Shows the relationship. The initial extrusion load here is a load obtained by subtracting the load generated by friction between the die and the material from the total load required for extrusion, that is, the load caused by the deformation resistance peculiar to the material. As is clear from FIG. 19, there is a quantitative relationship between <Mk> and the initial extrusion load regardless of the type of the trace addition element, and as <Mk> increases, the initial extrusion load also increases. I found out.

This suggests that <Mk> is an important parameter for evaluating the processing characteristics of the wrought aluminum alloy. Furthermore, by using such a strength characteristic index chart, it is considered that the load necessary for processing can be obtained, the material of the mold can be selected, or the design can be applied.

[Example 4] Evaluation of strength characteristics of a heat-treated material of an Al-Li alloy by <ΔMk>. 20 and 21 show Al-Li treated with T6, respectively.
The relationship between <ΔMk> and the tensile strength and 0.2% proof stress of the system alloys is shown. The tensile strength and the 0.2% proof stress of the Zr-free alloys indicated by ○ and △ and the Zr-added alloys indicated by ●, ▽, □, and ◇ increase as <ΔMk> increases, but the same <ΔMk>>, The latter alloy group has 15
0 to 200 MPa higher. This can be explained by the experimental fact that in an Al-Li-based alloy, by adding Zr, Al ₃ Zr becomes a preceding precipitation particle, and a form of a composite precipitate in which Al ₃ Li is precipitated is formed. It is considered to be a thing.

These facts suggest that the strength characteristics of Al-Li alloys can also be evaluated by <ΔMk>. Furthermore, it is suggested from the strength characteristic index diagram that changes in strength characteristics depending on the type of precipitate can be evaluated.

Example 5 Evaluation of strength characteristics of aluminum alloy for casting by <Mk> and <ΔMk>. Si, which is the main additive element of aluminum alloys for casting,
Too much does not form a solid solution in the aluminum solid solution and crystallizes as eutectic silicon. Further, Fe and Ni do not form a solid solution in the solid solution and form a compound. Therefore, in casting aluminum alloys, when determining <Mk> or <ΔMk> in the solid solution, the amount of Si in each alloy is 1
If the content exceeds%, the amount of solid solution Si is set to 1%. The contents of Fe and Ni were set to 0.052% and 0.05%, which are the maximum solid solubility limits in the binary system phase diagram, respectively. In an alloy system containing 1% or more of Si as an alloy element, eutectic silicon is crystallized according to the Si content, which contributes to the strength.
This contribution was obtained from the relationship between the Si content and the strength of the Al-Si binary alloy. The strength of the alloy system was determined by subtracting the amount from the standard strength value of each alloy. That is, the strength thus obtained can be regarded as almost representing the strength of the aluminum solid solution.

22 and 23 show the relationship between <Mk> and the tensile strength and 0.2% proof stress of the as-cast aluminum alloy for casting. As is clear from FIGS. 22 and 23, except for Al-Mg alloy system 7A and Si-rich 8A, etc., <Mk> and tensile strength and 0.2% proof stress are irrespective of the alloy system. There is a correlation between
It was found that the alloy having a larger <Mk> has a larger both strength characteristics.

FIGS. 24 and 25 show the relationship between <ΔMk> and the tensile strength and 0.2% proof stress of the casting aluminum alloy artificially aged after solution treatment. As is clear from FIGS. 24 and 25, Al—Zn—Mg-based alloy 771, Al—Cu—Mg-based alloy 1B and Mg
<ΔMk> and tensile strength and 0.
A correlation was found between the 2% proof stress, and it was found that the alloy having a larger <ΔMk> has a larger strength characteristic.

From these facts, also in the casting aluminum alloy, <Mk> is important for evaluating the strength characteristics of the as-cast aluminum alloy for casting and <ΔMk> for evaluating the strength characteristics of the heat-treated aluminum alloy. It turns out that it is a parameter. Furthermore, by using such a strength characteristic index chart, it is possible to predict the strength characteristics from the alloy composition without conducting a complicated experiment.

Example 6 An example of setting the alloy composition of a non-heat treatment type Al alloy. The use of aluminum in automobiles, that is, weight reduction, is being actively promoted with the aim of improving fuel efficiency and driving characteristics. Among them, body panel materials, along with suspension parts and radiators, are one of the fields where aluminum is expected to be the most promising as a substitute material for cold-rolled steel sheets. The main characteristics of this body panel material are strength and formability. As an alloy system that can satisfy both of them, a non-heat treatment type Al-Mg system, a heat treatment type Al-Cu system, and an Al-Mg-Si system.
The system is listed as a candidate material, and the development competition is unfolding. In that case, the development goals of strength and formability are:
Converted to tensile strength and elongation values, 30 kgf /
mm ² and 30% are listed.

In this example, a non-heat treatment type Al-Mg type alloy, which is one of the candidate materials, is taken up, a method of setting the components for the development of an alloy having both tensile strength and elongation is described, and the components are determined. The tensile test result of an alloy is shown.

In FIG. 26, the horizontal axis represents the amount of Mg added, which is the main alloying element of the present alloy system, and the vertical axis represents the Mn equivalent (the effect of Al and alloying elements other than Mg on the strength is converted as the effect of Mn). ) Is calculated based on the relational expression between the tensile strength and <Mk> as shown by the above-mentioned functional equation 3, In the figure, Al
-The composition position of the Mg-based practical alloy is shown by a black circle, the tensile strength is shown on it, and the elongation is shown in parentheses next to it. Tensile strength required for body panel material 30 kgf / mm ² (294MP
(a) is obtained at the alloy composition position shown by the dotted line.

Since the suppression of the crystallization compound is effective for improving the elongation, it is necessary to minimize the amount of alloying elements. Therefore, Mn was added to increase the recrystallization temperature with a small amount and to improve strength and stress corrosion cracking resistance. It has been experimentally confirmed that the addition of Mn to the present alloy system increases the elongation up to 0.2%, so the amount of Mn added was set to 0.2%. Furthermore, by contaminating the aluminum alloy with oxygen during melting or reducing the amount of hydrogen absorbed in the alloy, high temperature embrittlement is suppressed, and a rare earth element (hereinafter referred to as RE) or Y for improving hot rolling property is 0. 0.05% was added. Zr also has a large affinity with hydrogen,
Since it is effective for refining crystal grains, 0.05% was added. Since the addition amounts of these elements are very small and the influence on <Mk> can be neglected, the Mg amount is 5.3 from the intersection of the 0.2% Mn equivalent and the 30 Kgf / mm ² isointensity line in FIG.
%. In this way, Al-
Table 4 shows the results of a tensile test in which 5.3% Mg-0.2% Mn-0.05% RE (or Y) -0.05% Zr alloy was melted and the tensile test was performed together with the tensile properties of the existing alloy. . Both the strength and the elongation of this component-setting alloy were higher than those of existing alloys, which are candidate alloys for body panel materials.

[0038]

[Table 4]

[Embodiment 7] An example of alloy composition setting of a heat treatment type Al alloy. This example shows an example of alloy component setting of an Al-Mg-Si based alloy, which is another candidate material for the vehicle body panel material described in Example 6, and the result of the tensile test.

In FIG. 27, the horizontal axis represents the amount of Si added, which is the main alloying element of this alloy system, and the vertical axis represents the Mg equivalent (values obtained by converting the effect of alloying elements other than Al and Si on the strength as the effect of Mg). Then, the composition position at which the equal tensile strength is obtained is obtained based on the relational expression between the tensile strength and <ΔMk> as shown by the above-mentioned function formula 4. In the figure, Al
The position of the composition of the --Mg--Si based practical alloy is indicated by a black circle, the tensile strength is shown on it, and the elongation is also shown in parentheses next to it. Further, the maximum solubility limits of the Al-Mg-Si system and the Al-Si-Cu system are also shown by diagonal lines. The tensile strength of 30 kgf / mm ² (294 MPa) required for the body panel material can be obtained at the alloy composition position shown by the dotted line, but the composition position is above the maximum solid solution limit of the Al-Si-Cu system. . Since an increase in the amount of crystallized compounds causes a decrease in elongation, an Al-Si-Cu-based alloy composition having a maximum solid solubility limit of 30 Kgf / mm ² closest to the isointensity line, Al-1.1% Si-1. A 0.7% Mg equivalent was selected so that the Cu content in the Mg equivalent was higher than in the past. Further, RE, Y, and Zr, each having a large affinity with oxygen and hydrogen, were added in an amount of 0.05%. As an example, Al-1.1% Si-0.8% Mg-1.0%
A Cu-0.05% RE (or Y) -0.05% Zr alloy was melted and subjected to a tensile test. The results are shown in Table 5 together with the tensile properties of existing alloys. The composition-designed alloys have higher strength and elongation than the existing alloys that are candidate alloys for body panel materials.

[0041]

[Table 5]

[0042]

As described above, the strength characteristic of the aluminum alloy can be accurately represented by the strength characteristic index chart of the present invention. Conventionally, in the development, quality, and control of various properties of aluminum alloys, it has been customary to obtain the effect of alloying elements on these single or multiple properties by measurement and determine the optimum alloy composition from those data. Has been done in. These are very expensive, labor and time consuming and very inefficient, especially for multi-component alloys it is very difficult to do so. Further, when trying to develop an alloy by adding an element for which there are few experimental examples in the past, a huge amount of R & D investment is required. Even in such a case, the above-mentioned parameters are calculated in advance for the additional element, the strength characteristics are predicted using the strength characteristics index diagram, and the experiments are conducted on the alloy in a limited range, thereby significantly increasing the cost and labor. And time can be reduced.

In general, the upper limit and the lower limit of the constituent elements of aluminum alloys are defined by standards. However, when manufacturing or using a material, what is the value of the amount of elements specified in the standard, and how much can the value of elements (impurities, etc.) not specified in the standard be tolerated? , Is extremely important for practical use. Also for these, the kind and amount of each element can be comprehensively determined by an index diagram using the above parameters according to desired strength characteristics. From now on, it becomes possible to set a certain standard and control the quality.

Also, in the case of producing a new aluminum alloy in which a rare metal or an expensive metal is replaced with another metal,
Using the index diagram of the present invention, the optimum composition can be determined by such measures as adjusting the component metals that maintain various properties equivalent to those of conventional alloys. Not only is it possible to reduce the cost, but it is also possible to manufacture inexpensive products comprehensively, and not only the economic effect but also the resource saving effect is great.

[Brief description of drawings]

FIG. 1 is a perspective view of a cluster model.

FIG. 2 is a strength characteristic index diagram relating to the tensile strength of an annealed material of an wrought aluminum alloy.

Figure 3: 0.2 of annealed aluminum alloy for wrought
It is a strength characteristic index figure regarding% yield strength.

FIG. 4 is a strength characteristic index diagram relating to the tensile strength of a non-heat treatment type wrought aluminum alloy after cold working.

FIG. 5 is a strength characteristic index diagram regarding 0.2% proof stress after cold working of a non-heat treatment type wrought aluminum alloy.

FIG. 6 is a strength characteristic index diagram regarding Brinell hardness after cold working of a non-heat treatment type wrought aluminum alloy.

FIG. 7 is a strength characteristic index diagram regarding a shear strength of a non-heat treatment type wrought aluminum alloy after cold working.

FIG. 8 is a strength characteristic index diagram regarding the fatigue strength of a non-heat treatment type wrought aluminum alloy after cold working.

FIG. 9 is a strength characteristic index diagram relating to the tensile strength at 77K after cold working of a non-heat treatment type wrought aluminum alloy.

FIG. 10 is a strength characteristic index diagram regarding a 0.2% proof stress at 77K after cold working of a non-heat treatment type wrought aluminum alloy.

FIG. 11 is a strength characteristic index diagram regarding the tensile strength of a heat-treatable aluminum alloy that is naturally aged after quenching.

FIG. 12 is a strength characteristic index diagram relating to the tensile strength of a heat-treatable aluminum alloy that has been artificially aged after quenching.

FIG. 13 is a strength characteristic index diagram regarding a 0.2% proof stress of a heat-treated aluminum alloy that is naturally aged or artificially aged after quenching.

FIG. 14 is a strength characteristic index diagram relating to the Brinell hardness of a heat-treated aluminum alloy that is naturally aged or artificially aged after quenching.

FIG. 15 is a strength characteristic index diagram relating to shear strength of a heat-treated aluminum alloy that is naturally aged or artificially aged after quenching.

FIG. 16 is a strength characteristic index diagram relating to fatigue strength of a heat-treated aluminum alloy that has been naturally aged or artificially aged after quenching.

FIG. 17 is a strength characteristic index diagram relating to the tensile strength at 77K of the heat-treatable aluminum alloy that has been artificially aged after quenching.

FIG. 18 is a strength characteristic index diagram regarding 0.2% proof stress at 77K of the heat-treatable aluminum alloy artificially aged after quenching.

FIG. 19 is a strength characteristic index diagram regarding an initial extrusion load of an Al—Mg—Si alloy.

FIG. 20 is a strength characteristic index diagram relating to the tensile strength of an Al—Li based alloy that has been artificially aged after quenching.

FIG. 21 is a strength characteristic index diagram regarding the 0.2% proof stress of the artificially aged Al—Li alloy after quenching.

FIG. 22 is a strength characteristic index diagram regarding tensile strength of an as-cast aluminum alloy for casting.

FIG. 23 is a strength characteristic index diagram regarding 0.2% proof stress of an as-cast aluminum alloy for casting.

FIG. 24 is a strength characteristic index diagram regarding tensile strength of an aluminum alloy for casting that is artificially aged after quenching.

FIG. 25 is a strength characteristic index diagram regarding 0.2% proof stress of an aluminum alloy for casting that is artificially aged after quenching.

FIG. 26 is a strength characteristic index diagram showing isointensity lines of an Al—Mg—X (X is another alloy element) alloy.

FIG. 27 is a strength characteristic index diagram showing isointensity lines of an Al—Si—X (X is another alloying element) alloy.

Claims (3)

[Claims] 1. An average value <Mk> relating to the atomic fraction of the constituent element is calculated for the s-orbital electron energy level (Mk) _i of the constituent element i of the alloy, and <Mk> defined in this way is used as a parameter. As a result, the strength characteristic index diagram of the aluminum alloy, which shows the relationship between the strength characteristics of the non-heat treatment type wrought aluminum alloy and the as-cast aluminum alloy for casting and <Mk>. 2. The s orbital electron energy level (Mk) _{Al of} pure aluminum and the s of the element i constituting the aluminum alloy.
For the absolute value | (ΔMk) _i | of the difference (ΔMk) _{i from} the orbital electron energy level (Mk) _i , the average value <ΔMk> regarding the atomic fraction of the aluminum alloy constituent elements was calculated, and defined as The strength characteristic index diagram of the aluminum alloy showing the relationship between <ΔMk> and the strength characteristics of the heat-treatable wrought aluminum alloy and the cast aluminum alloy which has been heat treated after casting, using <ΔMk> as a parameter. . 3. The type and addition amount of the alloying element are determined so as to obtain desired characteristics by using the strength characteristic index diagram of the aluminum alloy according to claim 1 and 2, and these are compounded and melted. Aluminum alloy composition setting method.