JPS627836A - Manufacture of aluminum alloy having fine-grained structure - Google Patents

Abstract

PURPOSE:To provide a fine-grained structure by using an aluminum alloy containing specific amounts of 1 or >=2 elements among Fe, Mn, Cr and Zr and by allowing a plastic working stage of a specific working temp. and rate of strain to be included in the process of alloy manufacture. CONSTITUTION:The aluminum alloy has a composition consisting of, by weight, 0.05-2% Fe, 0.05-2% Mn, 0.05-0.35% Cr, 0.05-0.7% Zr, and the balance Al with inevitable impurities, to which 1 or >=2 kinds among 0.05-25% Si, 0.05-6% Cu, 0.05-6% Mg and 0.05-8% Zr are further incorporated, if necessary. In the manufacturing process of the above alloy, the plastic working stage of 250-480 deg.C working temp. and 1X10<-4>sec<-1>-1sec<-1> rate of strain is included.

Description

[Detailed Description of the Invention] Industrial Application Field This invention has a fine crystal grain structure and is suitable for various forming processes, forging processes, etc. as a rolled material such as rolled (A) extruded material, etc. Relates to a method for producing a superplastic aluminum alloy that exhibits excellent ductility.

In addition, in this detailed reading, "%" shall be indicated on a palm reading basis.

BACKGROUND OF THE INVENTION In recent years, various studies have been conducted on aluminum and aluminum alloys (hereinafter simply referred to as aluminum alloys) to impart high ductility and create superplastic alloys with good formability and forgeability. It is well known that the ductility of aluminum materials can be improved by refining the grain structure.
As a specific means for this purpose, it has conventionally been common practice to add transition elements such as Fe, Mn, Cr, and Zr to an aluminum alloy, and obtain a fine recrystallized structure by cold rolling and annealing. ing. The AA2004 alloy developed in the UK and known as 3upral is one of the representative examples. The alloy is AQ-6%Cu-0
It is reported that the basic structure is 4% Zr and the fine grain structure is made 1q by dynamic recrystallization, and that an elongation of 1000% or more can be obtained.

Problems to be Solved by the Invention However, like the above conventional alloys, Fe, Mn, Or
When using crystal and grain refining means that add transition elements such as However, it did not have enough superplasticity to be used as a material for various molding processes. Moreover, since the above-mentioned conventional alloys require ~cold working in the manufacturing process, there is also the drawback that the manufacturing process becomes complicated when attempting to obtain a fine grain structure after hot forming. Ta.

Means for Solving the Problems In view of the above problems, the inventors have been able to eliminate the need for cold working and further refine the crystal grains.
As a result of conducting various experiments and ω1 research with the intention of establishing the A manufacturing method, we found that transition elements Fc, Mn, and Q
It has been found that the desired purpose can be achieved by processing an aluminum alloy containing one or more of Zr and Zr under extremely low strain conditions under predetermined warm conditions after casting, This has led to the completion of the present invention.

Therefore, this invention has Fe: 0.05 to 2°0%, M
n: 0.05-2.0%, cr: o.

05-0.35%, Zr: 0.05-0.7%, or further contains Si;
0.05-25%, CU:O, 05-6%, Mg: 0
．． 05 to 6%, Zr; 0.05 to 8%, using an aluminum alloy containing one or more of Zr; 0.05 to 8%, and the balance consisting of aluminum and unavoidable impurities;
In step a, processing temperature: 250 to 480°C, strain rate: 'l x 10'SeC' to 1SeC' (7
) The gist is a method for producing an aluminum alloy having a fine grain structure, which is characterized by including a plastic working step.

The aluminum alloy used in the production method of this invention contains one of the transition elements Fe SMn, Cr, and Zl'.
It contains one or more types as essential ingredients. All of these elements are known to be useful for refining crystal grains, and therefore, if their content is less than the lower limit specified in the present invention, that is, less than 0.05%, the above effect cannot be achieved by 1q. . On the other hand, the upper limit of Fe;2
．． 0%, Mn: 2.0%, Cr: 0.35%, Zr
: If the content exceeds 0.7%, a large amount of crystallized substances will be generated during casting, resulting in a decrease in ductility.

If it contains the above-mentioned transition element, this invention can be applied to 10
Alloys based on No. 00 pure aluminum can also be used, but in order to be used as a material for various forming processes, PEGI aluminum alloys must often have sufficient mechanical strength. . In addition to the transition elements mentioned above, in addition to the above-mentioned transition elements, as a hardening element, s+: 0.05 to 25%, preferably 0.
．． 2-1.2%, Cu: 0.05-6%, preferably 1
．． 5-6.0%, M (1:0゜05-6%, preferably 0
．． 3-1.5%, Zn; 0.05-8%, preferably 0
．． S containing one or more of these types is used in a range of about 8 to 6%. If the content of each of these hardening elements is less than the lower limit, the required strength cannot be obtained in the alloy material, and if the content exceeds the upper limit and is excessive, coarse compounds are formed and the ductility is reduced. This results in a decrease in

Next, the plastic working that must be carried out during the manufacturing process of the present invention is not particularly limited in terms of its type, and may include various types such as stretching, extrusion, rolling, wire drawing, forging, and compression. Processing is included. However, the processing conditions are limited to a processing temperature of 250 to 480°C and a strain rate of 1x10 sec to 1 sec -1 (D range. If the processing temperature is less than 250°C,
Fe, Mn, and Cr are hard to form cells due to dislocations generated by processing, and are dissolved in solid solution.

Since Zr does not precipitate, it is not possible to obtain the effect of refining crystal grains. On the other hand, if the processing temperature exceeds 480° C., precipitation of the above-mentioned main hardening elements does not occur, so that grain refinement cannot be achieved in this case as well. The above processing temperature is the processing start temperature, and the processing end temperature is 200℃ with a width of about ±50℃ or less than the above humidity range.
The temperature range is 500°C.

Also, the strain rate of the alloy during processing is 1X 10
If it is less than 4 sec -1, the fine cells and fine recrystallized grains will not become small. On the other hand, if fast processing exceeding 1 sec-1 is applied, many dislocations will be introduced, making it difficult to stabilize the cell.
As a result, the pinning effect due to the precipitates is no longer sufficient,
It becomes impossible to achieve grain refinement. According to the experimental results, the most preferable range of processing conditions is approximately processing temperature: 350 to 400°C, strain rate: 1X10-4 to 1
x about 10-3 sec-'.

Effects of the Invention According to the present invention, as seen in the examples below, aluminum can be produced using a manufacturing process that does not require cold working, and has an extremely fine grain structure with an average grain size of 20 μm or less. Alloys can be obtained. Even if the material contains a hardening element and has sufficient mechanical strength, it is possible to obtain a similarly fine grain structure. Therefore,
It is possible to obtain an aluminum alloy that exhibits extremely high ductility, superplasticity, and excellent mechanical strength, and has much better formability than conventionally available high-ductility alloys. , it is possible to provide an aluminum alloy material with excellent casting processability.

By the way, the present invention'! ! The reason why the above-mentioned fine grain structure is obtained by the manufacturing method is that due to the processing conditions mentioned above, Fe, Mn, Cr, and Zr dissolved in the alloy precipitate on the subgrain or grains, resulting in a pinning effect. It is thought that this increases the crystal grain size, thereby delaying recrystallization and resulting in fine crystal grains.

Aluminum alloys with various compositions shown in Example Table 1 were made into aluminum alloys with a diameter of 75
It was cast into an M ingot using a water-cooled mold. And this ingot is 4
After extruding at 50℃ into a strip of 3cm x 30m,
The samples were plastically worked by special rolling under various processing conditions shown in 2. As for the comparative example, the sample was subjected to plastic stressing at a strain rate of 15 eC according to a conventional conventional method at air temperature, and then annealed at 400°C.

Table-1 Wipe chemical composition (wt
%) Saliva N(l Si CI M(It Z
n iFe Mn Cr Zr jA! 21--
--io, 2--one remainder 20.5-0.6-IO, 8--one remainder 3-4.50
．． 5-1-0.4-1 remaining example 4-1.42.14.7--
- o, 34. Remaining 5--4.6-(--0,25-Residual pressure 6-----1.3--1vv Table 2 For each sample obtained above, the average grain size in its alloy composition In addition to measuring the mechanical properties, the results were as shown in Table 3.

Table-3

Claims (2)

[Claims] (1) One or two of the following: Fe; 0.05-2.0% Mn; 0.05-2.0% Cr; 0.05-0.35% Zr; 0.05-0.7% Using an aluminum alloy containing at least 100% of aluminum with the remainder consisting of aluminum and unavoidable impurities,
In the manufacturing process of the alloy, processing temperature: 250-480°C, strain rate: 1 x 10^-^4sec^-^1-1sec
A method for producing an aluminum alloy having a fine grain structure, characterized by including a plastic working step of c^-^1. (2) One or two of the following: Fe; 0.05-2.0% Mn; 0.05-2.0% Cr; 0.05-0.35% Zr; 0.05-0.7% species or more, and Si; 0.
An aluminum alloy containing one or more of the following: 05-25% Cu; 0.05-6% Mg; 0.05-6% Zr; 0.05-8%, with the balance consisting of aluminum and inevitable impurities. using
In the manufacturing process of the alloy, processing temperature: 250-480°C, strain rate: 1 x 10^-^4sec^-^1-1sec
A method for producing an aluminum alloy having a fine grain structure, characterized by including a plastic working step of c^-^1.