JPH09125182A - Aluminum alloy for casting high in elongation - Google Patents

Abstract

PROBLEM TO BE SOLVED: To produce an aluminum alloy for casting high in elongation as cast. SOLUTION: This aluminum alloy for casting high in elongation has a compsn. contg. 1.5 to 2.5% Mg, 0.7 to 2.2% Mn and 0.40 to 0.9% Fe, in which the relation of 3 × Mg content + 6 × Fe content + 4 × Mn content <=15.0% is established among the contents of Mg, Fe and Mn, and contg. <=0.30% Si, <=0.50% Cu, <=0.3% Ti, <=0.1% B and <=0.1% Be, and the balance aluminum.

Description

Detailed Description of the Invention

[Industrial field of application] It is preferable to manufacture products having complicated shapes such as automobile parts, machine parts and electric equipment parts by casting, and it is possible to provide a lightweight aluminum alloy for casting which is large in casting. Is widely used and is extremely important in industry.

[Prior Art] Conventionally, not only JIS aluminum alloy castings but also other similar aluminum alloy castings have excellent mechanical strength and high toughness.

JIS AC7A has a large strength and elongation in the as-cast state, but has a drawback that the Mg content is large and thus the oxidation of Mg during the melt casting is severe, and casting defects are likely to occur. .

[0004] JISAC4CH has a relatively good castability and is a tough material, but it has a drawback that it has to undergo a rather troublesome heat treatment.

An aluminum alloy for casting which has a large elongation as cast is an Al-Si alloy or Al-Si-C.
It cannot be obtained with u-based alloys.

[Problems to be Solved by the Invention] As a result of intensive studies on various alloy systems, the inventors of the present invention provide an aluminum alloy for casting which has good castability and has a large elongation as cast. Is.

[Means for Solving the Problems] The present invention provides a casting aluminum alloy having a large elongation by strictly controlling the contents of Mg, Mn and Fe in the aluminum alloy.

The gist of the present invention is that the Mg content is 1.5 to 2.5.
%, Mn content 0.7 to 2.2%, Fe content 0.40
~ 0.9% and 3 × between the contents of Mg, Fe and Mn
Mg content + 6 × Fe content + 4 × Mn content ≦ 15.
0% relationship is established, Si content is 0.30% or less, Cu
Content 0.50% or less, Ti content 0.30% or less, B
An aluminum alloy for casting having a large elongation, characterized in that the content is 0.1% or less, the Be content is 0.1% or less, and the balance is aluminum.

In the present specification, the content of alloying elements is expressed as a weight percentage.

In the present invention, Mg improves the mechanical strength and castability of the alloy. However, if the content is too large, an oxide film is liable to be formed during melt casting, and the elongation is lowered. On the contrary, if the content is too small, mechanical strength and fluidity are lowered. Therefore, the Mg content is set to 1.5 to 2.5%.

Like Mg, Mn improves the mechanical strength and castability of the alloy. However, if the content is too large, the mechanical strength and toughness will decrease, and conversely, if the content is too small, the mechanical strength and castability will decrease. Therefore, the Mn content in the alloy is set to 0.7 to 2.2%.

Like Mn, Fe also improves the mechanical strength and castability of the alloy. However, if its content is too high,
Toughness and fluidity are reduced, and solidification shrinkage cracking is likely to occur. On the contrary, if the content is too small, casting cracks are likely to occur. Therefore, the Fe content in the alloy is 0.40 to 0.9%
And

If Fe and Mn are alloyed in a large amount, a coarse FeMn compound will be formed and the toughness will be impaired.
The Fe and Mn contents are limited within the range where the relationship of × Fe content + 2 × Mn content ≦ 5.3% is established.

Furthermore, if the content of Mg, Fe and Mn is 3 ×
Mg content + 6 × Fe content + 4 × Mn content ≦ 15.
The contents of Mg, Fe and Mn are limited within the range where the relation of 0% is established.

Since Fe has the effect of preventing the molten alloy from sticking to the die during die casting, the present invention provides a material that is well suited to die casting, high pressure casting, etc. in addition to gravity casting. is there.

The alloys of the present invention do not require heat treatment.

In the present invention, Ti, B and / or Be may be alloyed if necessary.

Ti refines the crystal grains of the casting, reduces the shrinkage,
Improves cast crackability. The Ti content is 0.30% or less, preferably selected from the range of 0.05 to 0.20%.

If, in addition to Ti, 0.1% or less of B, preferably 0.001 to 0.05% of B is made to coexist with Ti,
Furthermore, the effect becomes remarkable.

When Be is alloyed in an amount of 0.002% or more, it has the effect of preventing the oxidation of Mg in the molten aluminum alloy and improving the strength and elongation of the casting. However, Be is alloyed in excess of 0.1%. Since the effect does not change, the Be content is set to 0.1% or less, preferably 0.002 to 0.05%.

S as an impurity usually contained in the present invention
i should be 0.30% or less and Cu should be 0.50% or less.

[Effects of the Invention] As described in detail above, the present invention provides Mg, Mn, and F in an aluminum alloy.
By strictly controlling the e content, an as-cast as-cast aluminum alloy having a large elongation is provided.

EXAMPLES Next, the present invention will be described in more detail by way of examples, but the present invention is not limited to the following examples unless it exceeds the gist.

Example 1 Alloys having the chemical components shown in Table 1 were melted, and were JIS at 750 ° C.
Tensile properties and Brinell hardness were measured as mechanical properties of the ingot obtained by casting in a No. 4 boat mold (room temperature).

The fluidity of a part of the molten metal was measured using a spiral fluidity test mold. The casting temperature at that time is 730
The mold temperature was 330 ° C.

Table 2 shows the test results. Although the shrinkage amount slightly increased as the Mg content increased, the fluidity improved. Further, the tensile strength increases as the amount of Mg increases, but the elongation decreases, so the Mg content is 1.5-2.
It can be seen that it must be within the range of 5%.

Alloy No. Reference numeral 1 indicates the alloy of the present invention, which is an aluminum alloy for casting having a large elongation.

Example 2 FIG. 1 shows the results of measuring the tensile properties of JIS No. 4 boat mold ingots for alloys in which the contents of Mn and Fe of Al-1.8% Mg alloy were mixed in various proportions. This is a summary of the areas that share a large amount of elongation and tensile strength.

The area has a tensile strength of 186 N / mm ²
As described above, a region having an elongation of 19% or more is shown, and a region having a tensile strength of 196 N / mm ² or more and an elongation of 20% or more is shown.

FIG. 2 shows the contents of Mn and Fe showing an elongation of 20% when the Mg content of the Al--Mg system alloy is changed from 1.5 to 2.5%, and the Mg content increases. It can be seen that the Mn content must be decreased as the Mn content increases, and the Fe content also changes as the Mn content decreases.

In the Al-1.5% Mg system, the relationship of 3 × Fe content + 2 × Mn content = 4.8% is established between Fe and Mn. In the Al-2.5% Mg system, the relationship of 3 x Fe content + 2 x Mn content = 3.3% is established between Fe and Mn. Further, the relationship of 3 × Mg content + 6 × Fe content + 4 × Mn content = 14.1% is established between Mg, Fe and Mn.

Example 3 FIG. 3 shows an outer diameter of 58 m for Al-1.8% Mg alloy.
The results of the casting cracking test when cast at 750 ° C. in a ring-shaped die (room temperature) having an m, an inner diameter of 48 mm and a height of 20 mm are shown.

Regarding the cast cracking property, the condition of cracking was judged by observing with the naked eye.
Those that did not result in fracture even when cracked were marked with a triangle, and those with shrinkage cracks on the free solidified surface were marked with a triangle.

When the Mn content is in the range of 0.7 to 2.2%, the Fe content at which casting cracks do not occur is 0.40 to 0.9%.
It can be seen that it is.

Example 4 For the Al-1.8% Mg-based alloy shown in Table 3, Mn,
Table 4 shows the results of examining the influence of the Cu and Si contents on the tensile properties and castability in the same manner as in Example 1.

It can be seen that the elongation increases as the Mn content decreases, but the tensile strength and fluidity decrease when the Mn content is less than 0.7%. Further, when the Mn content exceeds 2.2%, the tensile strength is lowered and the elongation is remarkably lowered.

Even if the Cu content is 0.31%, the mechanical properties and castability are not adversely affected, but the Si content is 0.54%.
It can be seen that when it is contained, the elongation is remarkably reduced.

Example 5 Table 6 shows the results of measuring the tensile properties, hardness, fluidity and casting crackability of No. 4 boat mold ingots for the alloys having the chemical components shown in Table 5. It can be seen that the alloys of the present invention have the same or higher castability and mechanical strength as compared with the comparative alloys, and have a large elongation.

[0039]

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing regions of Fe and Mn that share large elongation and tensile strength of an Al-1.8% Mg-based alloy.

FIG. 2 shows a Mg content of an Al-Mg alloy of 1.5-2.
Fe showing a large elongation of 20% when changed to 5%
It is explanatory drawing which shows the content of Mn.

FIG. 3 is an explanatory diagram showing concentration ranges of Fe and Mn in which casting cracking of an Al-1.8% Mg alloy does not occur. [Explanation of Codes] 1. The region of FIG. 1 is an explanatory diagram showing a region having a tensile strength of 186 N / mm ² or more and an elongation of 19% or more. 2. The region of FIG. 1 is an explanatory view showing a region having a tensile strength of 196 N / mm ² or more and an elongation of 20% or more. 3. The ◯ mark in FIG. 3 indicates that there were no casting cracks. 4. The X mark in FIG. 3 indicates that there were casting cracks. 5. The mark Δ in FIG. 3 indicates that even if there were casting cracks, the fracture did not occur. 6. The ▲ mark in FIG. 3 indicates that shrinkage cracks were observed on the free solidified surface.

[Table 1]

[Table 2]

[Table 3]

[Table 4]

[Table 5]

[Table 6]

Claims (1)

[Claims] 1. A Mg content of 1.5 to 2.5%, a Mn content of 0.7 to 2.2%, an Fe content of 0.40 to 0.9% and a content of Mg, Fe and Mn. 3 × Mg content between +
The relationship of 6 × Fe content + 4 × Mn content ≦ 15.0% is established, Si content is 0.30% or less, Cu content is 0.5.
0% or less, Ti content 0.30% or less, B content 0.1
%, A Be content of 0.1% or less, and the balance aluminum, a casting aluminum alloy having a large elongation.