JPS6244540A - Manufacture of high-strength aluminum alloy member - Google Patents

Abstract

PURPOSE:To manufacture a high-strength Al alloy member of prescribed shape by solidifying an Al alloy containing specific amounts of Mn, W and Ni by rapid cooling at a specific cooling velocity to be formed into a powdery solidified matter and by subjecting it to preforming and to hot forming at a specific temp. CONSTITUTION:The Al alloy consisting of, by weight, 4.0-12% Nn, 0.2-4.0% W, 0.5-4.0% Ni and the balance Al with inevitable impurities and satisfying (Mn+Ni)=8-14% is refined. This Al alloy is solidified by rapid cooling at a cooling rate of >=10<3> deg.C/sec to prepare the solidified matter in the form of powder or foil. Subsequently, the above solidified matter is hot-formed, once at least, at <=500 deg.C in the above state or after subjected to preforming so as to manufacture the Al alloy member of prescribed shape. In this way, the high-strength Al alloy member having moderate elongation can be obtained.

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention provides a method for producing a high-strength aluminum alloy member of a predetermined shape by hot forming an aluminum alloy solidified body prepared by a rapid solidification method. The present invention relates to a method of manufacturing a high-strength aluminum alloy member.

[Prior art and its problems]

In recent years, new types of alloys produced by the rapid solidification method are expected to be applied in various fields. The rapid solidification method enables the formation of uniform solid solutions of alloying elements, the formation of supersaturated solid solutions, and the fine dispersion of intermetallic compounds, which were previously considered difficult. In some cases, alloys can be obtained, and the properties of alloys can be greatly improved.

However, the rapid solidification method generally involves rapidly cooling a small amount of a molten alloy by contacting it with a large amount of a gaseous or liquid cooling medium, or by causing it to flow down onto a rapidly moving cooled solid surface. The solidified metal obtained by this method can be powdered, flaky or thin-walled. It has no choice but to take on a microscopic shape, such as a cylindrical shape.

Therefore, the microscopic solidified metal thus obtained needs to be processed into a member of a predetermined size, except for special purposes in which it is used in its microscopic shape. For example, in order to manufacture aluminum alloy members such as plates, bars, and profiles for structural materials from microsolidified aluminum alloys produced by the rapid solidification method, microsolidified aluminum alloys are generally used. A forming process is required in which a preform is prepared by collecting and compressing the preform, and then the preform is subjected to a forming process by stretching such as rolling, extrusion, or forging.

The above-mentioned forming process is preferably carried out hot from the viewpoints of firm adhesion of micro-shaped solidified metals by thermal activation and reduction of power during forming and processing. However, when hot forming is performed, the favorable non-equilibrium structure formed by rapid solidification returns to an equilibrium state through thermal activation, resulting in the loss of most of the properties obtained by rapid solidification. There's a problem. This is because the supersaturated solid solution formed by rapid solidification thermally decomposes into a solid solution and an intermetallic compound at the same concentration, and the fine quality structure becomes coarser, thereby altering the quality of the rapidly solidified structure.

In the case of aluminum alloys manufactured by conventional melting and casting methods, the amount of solid solution of transition metal elements such as Fe is approximately Q, 1wt,% in the equilibrium state, whereas in the case of rapidly solidified aluminum alloys, it is approximately IQwt,%. will be increased to Therefore, it is relatively easy to obtain rapidly solidified aluminum alloy powders and flakes with a Guitzkaas hardness of 200 or more.
If a thin ribbon-shaped rapidly solidified aluminum alloy is directly subjected to a tensile test, it will exhibit a tensile strength of 50 Kqf/m- or more. However, when such a rapidly solidified aluminum alloy in the form of a microsolid is subjected to forming processing including hot stretching to form a member into a predetermined shape, the Witzkars hardness of the member is approximately 100. and,
The tensile strength decreases to about 30 Kgf/m- and the high hardness and high strength properties obtained by rapid solidification are lost.

In order to prevent such a decrease in hardness and strength, if the forming process is performed cold, the strong surface oxide film unique to aluminum alloys will prevent the microsolids from adhering to each other.
It is not possible to obtain high-quality molded parts. Therefore, if the above-mentioned forming process is performed at a temperature of 200 to 300°C, so-called warm temperature, there will be relatively little thermal decomposition of the rapidly solidified structure and it will be possible to fix the microsolids, but on the other hand, for forming The large force required limits the size and shape of the molded part obtained, and special equipment is required for molding, making it impractical.

[Purpose of the invention]

Therefore, it is an object of the present invention to produce high-strength aluminum alloy members by the rapid solidification method, without causing a decrease in strength even when subjected to hot drawing, and to achieve the excellent properties obtained by rapid solidification. The object of the present invention is to provide an alternative method for manufacturing a high-strength aluminum alloy member that retains its properties and has appropriate ductility.

[Summary of the invention]

In manufacturing high-strength aluminum alloy members by the rapid solidification method, the present inventors have discovered that there is no decrease in strength even when hot drawing is performed, and that the excellent properties obtained by rapid solidification are excellent. Intensive research was conducted to develop a method that would preserve this.

As a result, the present inventors have previously discovered that the hardness and strength of an aluminum alloy containing a predetermined amount of manganese and tungsten can be increased by rapid solidification, and that the properties obtained by this rapid solidification can be improved within a predetermined temperature range. It was found that there was almost no change when hot forming was performed.

An aluminum alloy member obtained by hot forming a rapidly solidified body of A/-Mn-W alloy with It has been found that when a preformed Al-Mn-W alloy such as a billet used for extrusion becomes large, its ductility decreases, making it impossible to obtain a high-strength aluminum alloy member with ductility that is necessarily satisfactory for practical use. .

Therefore, as a result of further research to solve the above-mentioned problems, the present inventors have found that if a part of manganese is replaced with a predetermined amount of nickel, the strength after hot working will be higher than that of Al-Mn-W alloy. Moreover, it was found that the ductility was significantly improved and the tensile elongation was more than doubled.

This invention was made based on the above findings, and includes: Mn: 4.0-12 wt.%, W: 0.2-4. Qwt, Chi, Ni: 0.5-4. Qwt, however, Mn + Nl is 8 to 14 Wt%, the balance is aluminum and unavoidable impurities. A powder or flake solidified body is prepared by rapid solidification at a cooling rate, and the solidified body thus obtained is heated at least once at a temperature of 500°C or less, either as it is or after being preformed. The method is characterized in that an aluminum alloy member having a predetermined shape and high strength is produced by interforming.

[Structure of the invention]

In this invention, the reason why the chemical composition range of the aluminum alloy is limited as described above will be described below.

(1) Manganese (Mn) Manganese is a transition metal element along with iron and the like, and when it is precipitated as a supersaturated solid solution or finely dispersed in aluminum by the rapid solidification method, it has the effect of significantly improving the strength. Additionally, due to slow thermal diffusion, AA-Mn alloys have excellent thermal stability and exhibit high strength at high temperatures up to about 300°C. Comparing the Al-Mn alloy with the Al-Fe alloy, the Al-Mn alloy tends to form a supersaturated solid solution even at a lower cooling rate than the Al, -1;'e alloy, and its melting point is lower, making it easier to melt. It has properties superior to Al-Fe alloys, such as high elastic modulus and excellent corrosion resistance.

Manganese content is 4. If the manganese content is less than 1, the desired effect cannot be obtained in the above-mentioned action, and on the other hand, even if the manganese content exceeds 12 wt. If the amount is too large, a problem arises in that ductility decreases. Therefore, the manganese content is
It should be limited within the range of 4.0 to 12 Wt,%.

(2) Tungsten (W) Al-Mn alloy has the above-mentioned excellent properties, but it has the problem that the above-mentioned properties are significantly reduced due to thermal decomposition during hot forming processing performed after rapid solidification. There is.

Tungsten solves the above-mentioned problems of Al-Mn alloys, and the addition of tungsten slows down the thermal decomposition of the rapidly solidified structure that occurs during rapid solidification.
It has the effect of significantly improving the strength of aluminum alloy members due to the combination of rapid solidification and hot forming.

If the tungsten content is less than 0.2 wt.%, the desired effect described above cannot be obtained, while if the tungsten content exceeds 4.0 wt.%, a large amount of intermetallic compounds will be produced. If the thickness is too high, a problem arises in which ductility decreases.

Therefore, the tungsten content is between 0.2 and 4. Ow
t, should be within the range of %.

(3) Nickel (Ni) Nickel, like manganese, has the effect of improving strength. Furthermore, by adding nickel to the Al-Mn-W alloy, the ductility of the aluminum alloy member by a combination of rapid solidification and hot forming is significantly improved, and in particular, when part of the manganese is replaced with nickel, the strength is increased. However, the ductility is improved to the extent that the tensile elongation is more than doubled.

If the nickel content is less than Q, 5wt, 1, the desired effect described above cannot be obtained; on the other hand, if the nickel content is less than 4wt. When Qwt, % is exceeded, the amount of Al-Mn-Ni intermetallic compounds produced is too large, resulting in a problem of lowering the ductility. Therefore, the nickel content is 0.5
From 4. Qwt, should be within the range of %.

(4) Amount of (Mn + Ni) As mentioned above, the strength of a rapidly solidified aluminum alloy is determined by the amount of (Mn + Ni)! It is also retained in the member.

If the amount of (Mn+Ni) is less than 8 wt.%, the desired strength cannot be obtained. On the other hand, if the amount of (Mn+Ni) exceeds 14 wt.%, the amount of intermetallic compounds produced is too large, resulting in a problem of decreased ductility. Therefore, the amount of (Mn+Ni) is from 8 to 1
It should be within the range of 4wt.%.

AA within the above-mentioned composition range! -Mn-W-Ni alloy exhibits high strength properties by rapid solidification from a molten state, but the cooling rate should be 103° C./see or higher. That is, by rapidly cooling a melted aluminum alloy having the above-mentioned composition at a cooling rate of 103° C./sec or higher and hot forming a powdery or flaky solidified body, conventional high-strength aluminum can be produced. A high-strength aluminum alloy member can be obtained that has room temperature strength comparable to alloys and heat resistance and rigidity that exceed conventional alloys.

If the cooling rate is less than 103° C./SeC, the alloying elements will not form a sufficient solid solution and coarse intermetallic compounds will precipitate, making it impossible to obtain an alloy member with excellent strength and ductility through hot forming. In addition, even if powder or flakes that have been rapidly solidified at a cooling rate of 105°C/See or the like by means such as a rotating roll method are used, the strength of the hot-formed alloy member will hardly be improved; Rather, it should be noted that the rapid solidification method is not economical and increases manufacturing costs.

The cooling rate by ordinary gas atomization method or water atomization method is 102 to 104°Q/Sec, and the cooling rate by improved gas atomization method or rotating roll method is 104 to b. This can be done by the known methods mentioned above.

Powder-like, flaky solidified material obtained by rapid solidification under the above conditions, or flaky micro-solidified material obtained by cutting a thin ribbon, or finely ground powder as required, It is necessary to hot-form the material as it is or after preforming it into a desired shape, such as a plate, bar, profile, etc., at least once.

Such hot forming processing can be performed by known means such as hot Soles, hot isostatic pressing (HIP), hot rolling, hot extrusion, and hot forging.

The processing temperature during hot forming should be 500°C or less. That is, when the processing temperature exceeds 500°C, the rapidly solidified structure undergoes rapid thermal decomposition, making it impossible to obtain the desired strength. The preferred temperature range is 350 to 480°C, and if the forming process is performed in this temperature range, thermal decomposition of the rapidly solidified structure is almost suppressed, and the formed alloy member exhibits practically meaningful strength characteristics. In addition, it does not exceed the capabilities of molding equipment that is generally used industrially.

[Embodiments of the invention]

Example 1 Two types of alloys A and B having compositions within the range of the present invention shown in Table 1 were melted. This alloy A.

B was re-melted, the molten metal was atomized by spraying argon gas as a cooling medium, and the following two types of rapidly solidified powders were prepared by setting atomization conditions and sieving the atomized powder.

(1) Cooling rate: 1 O2~less than 10"C/sec Particle size: 32~100 mesh (500~150μm) (2
) Cooling rate: 103-b Particle size knee 100 mesh (average particle size about 44 μm) The above-mentioned rapidly solidified powder was hot pressed at a temperature of 400° C. and preformed into a billet with a diameter of 150 words. The billet described above was then hot extruded at a temperature of 450 to 510° C. and an extrusion ratio of 25 to produce a round bar with a diameter of 30 ttIL.

Table 2 shows the alloys A1-4 of the present invention produced in this way.
and the component compositions of comparative alloys 1 to 4, the cooling rate of the rapidly solidified powder, the extrusion temperature during hot extrusion, and the tensile properties at room temperature. Comparative alloy flats I and A2 have slow cooling rates that are outside the range of the present invention, and comparative alloys A3 and A4 have high forming temperatures by hot extrusion that are outside the range of the present invention.

Table 1 As is clear from Table 2 above, alloys 1 to 4 of the present invention are excellent in both tensile strength and elongation. On the other hand, comparative alloys A1 and A2 have rounded tensile strengths because their cooling rates are slow and out of the range of the present invention. However, comparative alloy metal 3 and cup 4 had a high molding temperature (extrusion temperature) outside the range of the present invention, so both tensile strength and elongation were poor.

Example 2 As shown in Table 3, inventive alloys A5 to 10 having component compositions within the range of the present invention and comparative alloys A5 to I4 having component compositions outside the range of the present invention were melted. These alloys are remelted and the molten metal is argon gas atomized by spraying argon gas as a cooling medium.
The mixture was rapidly cooled, solidified, and sieved to prepare a -100 mesh rapidly solidified powder. Its cooling rate is 103~1
It was 0'''C/see.

This rapidly solidified powder was hot pressed at a temperature of 400'C and preformed into a billet with a diameter of 15011B.

The billet described above was then multi-hot extruded at a temperature of 450° C. and an extrusion ratio of 25 to produce a round bar with a diameter of 301,111 mm. Table 3 shows the tensile strength and elongation at room temperature of the round bars produced in this way, as well as the
The tensile strength at 0°C is also shown.

Comparative alloy A5 has a Mn content outside the range of the present invention.

Comparative metal alloys 6 and A8 do not contain W, and flat metal 7 does not contain Ni. Comparative Alloy No. 9 has a Ni content outside the range of the present invention. Comparative alloy AIO does not contain W and Ni, and A 11 does not contain Ni. Comparative alloy A I 2 has a W content outside the range of the present invention, and A
No. 13 has a Mn+Ni content outside the scope of the present invention,
In A14, the Mn content and the Mn+Ni content are outside the scope of the present invention.

As is clear from Table 3, the alloy shops 5 to 10 of the present invention are
All of them have high tensile strength and moderate elongation, and their room temperature strength is comparable to that of the 2000 series alloy (
AI-Cu alloy) and 7000 series alloy (Al-
Comparable to the strength of Zn-Mg alloy). In addition, among conventional aluminum alloys for wrought use, alloys with relatively high high temperature strength are the above-mentioned 2000 series alloys and 5000 series alloys (Al-Mg alloys). Tensile strength is 15Kgf/mm'
It is as follows.

On the other hand, the tensile strength of the alloy of the present invention at 250°C is 25 Kpf/mm' or more, and has extremely high high temperature strength compared to conventional aluminum alloys. On the other hand, comparative alloys A5 to A14, which are outside the scope of the present invention, are all inferior in tensile strength or elongation, and are significantly less practical.

〔Effect of the invention〕

As detailed above, according to the method of the present invention, it is possible to achieve room temperature strength comparable to conventional high-strength aluminum alloys such as 2000 series alloys and 7000 series alloys, and extremely high temperature strength compared to conventional aluminum alloys. Has strength,
In addition, it is possible to produce aluminum alloy members with appropriate elongation, and the production can be carried out by the same hot forming process as conventional melt-casting materials, so it can be used in a wide range of applications. Many industrially excellent effects are brought about.

Claims (1)

[Claims] Mn: 4.0 to 12wt. %, W: 0.2-4.0wt. %, Ni: 0.5-4.0wt. %, however, Mn+Ni is 8 to 14 wt. %, Remaining: An aluminum alloy having a composition consisting of aluminum and unavoidable impurities is melted, and then the aluminum alloy is heated at 10^3°C/sec.
Rapid solidification is performed at the above cooling rate to prepare a powder or flaky solidified body, and the solidified body thus obtained is heated as it is or after being preformed at least once at a temperature of 500°C or less. A method for producing a high-strength aluminum alloy member, which comprises hot forming and thus producing an aluminum alloy member having a predetermined shape and high strength.