JPS61250142A - High strength aluminum alloy excelling in hardenability - Google Patents

Abstract

PURPOSE:To provide excellent hardenability as well as high strength by limiting the content of Mn, Cr and Zr and further by incorporating proper amounts of rare earth elements in an Al-Mg-Si alloy. CONSTITUTION:In the Al-Mg-Si alloy of JIS No.A6000 type as a base, the amounts of Mn, Cr and Zr to be added as grain refining elements are limited to <=0.4%, <=0.15% and <=0.15%, respectively, and 0.5-10% of >=1 element among rare earth elements is incorporated. Y, La, Ce, Pr, Nd, Sm, etc., are suitable as the rare earth elements. Owing to the above composition, a high strength alloy having superior hardenability can be practically provided as extruded material or drawn material.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application This invention relates to high-strength aluminum alloys, particularly An-Mg alloys, used as structural materials for vehicles, structures, etc.
-8i series high strength aluminum alloy.

Conventional technology and problems Traditionally, high-strength aluminum alloys, especially JIS A
A method of controlling the crystal grains of 6000 series alloys is to add one or more of Mr, Cr, and Zr. It is well known that this type of element is finely precipitated by homogenization treatment after casting of the alloy, thereby refining the crystal grains. But on the other hand,
These fine precipitates of elements are called insoluble compounds because they do not form a solid solution during solution treatment, and they become sites for the heterogeneous precipitation of solute elements during cooling, promoting precipitation at relatively high temperatures, resulting in coarse precipitates. There is a tendency that a lot of substances are generated, and even if a subsequent aging treatment is performed, the strength cannot be improved sufficiently.

That is, a phenomenon is observed in which the hardenability deteriorates. In particular, to ρ
-Mg-8i alloys have the disadvantage that the addition of Cr and Mn makes it difficult to obtain a hardening effect.

In view of the above, it is an object of the present invention to provide a high-strength An-Ma-3i alloy that can be made to have finer grains without reducing its hardenability.

Means for Solving the Problems The present invention achieves the above-mentioned purpose by using high-strength A6000.
Mr. N
The main idea is to add a rare earth element instead of r and Zr.

Motsutomo, Mr2, Cr2, and Zr also have the effect of refining crystal grains, so their addition is useful as long as it does not impede hardenability, and their inclusion is not avoided.

Therefore, the gist of this invention is that JIS A
Based on No. 6000 series Ω-Mg-3i alloy, Mn: 0.4% or less, Cr: 0.15% or less, Zr
: Their content is regulated to 0.15% or less, and one or more rare earth elements are 0.5% to 10%.
It is a high-strength aluminum alloy with excellent hardenability, characterized by a content in the range of %.

A60006000 series, so M
g: 0.35-1.5%, Si: 0.20-1.2
% content is mandatory.

Needless to say, these 1yln and 3i have an effect on improving the strength of the alloy, and if they are less than the lower limit direct value, the alloy strength will be insufficient, and if they exceed the upper limit, extrusion workability will deteriorate.

The rare earth elements that are necessary to be added are not particularly limited, but specifically, for example, Y, La SCe 1P
Preferred examples include r 2 , Nd 2 , Sm, and the like. This I[[a group element is mainly effective in refining crystalline materials, and in view of this effect, in the present invention, all elements of the same group (rare earth elements) are substantially equivalent to each other. It is rated as Uruchino. Therefore, one type or two or more of them can be used in any combination, but if the total content in the alloy is less than 0.5%, it is not sufficient for the grain refinement effect, and if the content exceeds 10%, A lot of crystallized substances are generated, which has the disadvantage of reducing the strength of the alloy.

Since M'', C'', and zr are useful for the effect of refining crystal grains as mentioned above, it is preferable and recommended to include one or more of them as long as they are within the specified amount range. .

Mr: 0.4%, Cr: 0.15 as specified above
%, Zr: If it exceeds 0.15%, a large amount of coarse precipitates will be generated, resulting in the disadvantage of reducing hardenability.

Effects of the invention This invention essentially has high strength JIS A6061.6
351 etc' (F) An-fvto-3i series (600
0 series) alloy, it not only has high strength suitable for structural material use, but also has Mr, Cr,
By restricting the content of Zr and containing rare earth elements, it is possible to have an excellent crystal grain refinement effect without deteriorating hardenability, and as a result, it is possible to easily obtain a hardening effect. Since a fine recrystallized structure is created by the addition of rare earth elements, surface recrystallization does not occur during extrusion, resulting in excellent extrusion processability, and the crystal grains do not become coarse during solution treatment. An aluminum alloy extruded structural material with good strength and surface condition can be obtained.

Examples Alloys having various chemical compositions shown in Table 1 below were cast in a 3-inch water-cooled mold, and then homogenized at 560° C. for 8 hours. Then 3am+X30aw at 500℃
The cooling rate after extrusion is divided into two types, one type is the cooling rate of 40°C/min (temperature: T5).
), the other one is water cooled (temperature: T6), and then one more
Artificial aging treatment was performed at 80° C. for 7 hours to obtain various alloy samples with different tempers.

Note that Comparative Example 11k17 is a conventional A6061 alloy, and Comparative Example 8 is an A6351 alloy.

[Margins below] Then, tensile tests were conducted on the various alloy samples described above, and the grain sizes of their crystal grains were measured. The results are below
It was as shown in the table.

Table 2 As shown in Table 2 above, the alloy of the present invention has a small difference in strength between water cooling and air cooling after extrusion.
In particular, compared to the conventional A60616061 Alloy 1 alloy in which crystal grains are controlled by adding ly[r 2 and Cr 2 , the number of crystal grains is significantly smaller, and it is found that the alloy has excellent quenching sensitivity.

Patent applicant Showa Aluminum Co., Ltd. Procedural Amendment 1, Case Indication 1985 Patent 1 [Relationship with Case No. 91841]
Patent Applicant Care 6-224 Kaiyama-cho, Sakai City Name Showa Aluminum Co., Ltd. 5 Date of amendment order Voluntary amendment) 6 Number of inventions increased by amendment 8 Contents of amendment (1) Details Correct rMrJ on page 2, line 2 of the book to rMnJ.

(2) In the same book, page 2, line 9, ``Iwareteiori'' is corrected to ``Iwareteori''.

(3) "Mr" in lines 6 and 9 of page 3 of the same book is corrected to rMnJ.

(4) "Can be shown" on page 4, line 13 of the same book is corrected to "can be shown."

(5) r on page 5, lines 4, 8, and 17 of the same book
Correct Mr J to rMn'J.

(6) Correct rMr J on page 9, line 4 of the same book to rMnJ.

Written amendment to the above procedure ■1 June 12, 1985 Patent Application No. 91841 3, Relationship with the case of the person making the amendment Patent applicant (l), 6-224-4, Kaiyama-cho, Sakai City
, Representative 6 I, Parent 5, Date of amendment order (voluntary amendment) 6, Number of inventions increased by amendment 8, Contents of amendment (1) Next to "in particular" on page 1, line 17 of the specification , insert "as a wrought material".

(2) Following “Arises” on page 5, line 11 of the same book,
Add the following sentence.

"Although the alloy according to the present invention is mainly used as an extruded material, it can also be used in other wrought materials as a high-strength alloy with good hardenability."that's all

Claims (1)

[Claims] Based on JIS A6000 series Al-Mg-Si alloy, Mn: 0.4 or less, Cr: 0
．． The content is regulated to 15% or less, Zr: 0.15% or less, and one or more rare earth elements are contained in the range of 0.5% to 10%. A high-strength aluminum alloy with excellent hardenability.