JP3159384B2 - Method for producing aluminum alloy powder for forging - Google Patents

Description

The present invention relates to a method for producing an aluminum alloy powder formed by forging.

[Problems to be Solved by Conventional Technology and Invention] Conventionally, as an aluminum alloy powder formed by forging, an aluminum alloy powder obtained by a rapid solidification method has been used. The aluminum alloy powder obtained by such a rapid solidification method was an extremely fine powder having an average particle size of 40 μm.
For this reason, the fluidity is poor and does not flow well in the mold, and as a result, the density in the molded body varies,
The strength of the forged body varied. In addition, because of the fine powder, there is a problem in that the powder enters into the gap of the mold and seizure occurs during molding of the mold. In addition, since it easily rises as dust, there is a problem in safety and health.

When manufacturing aluminum alloy powder by the atomizing method in which molten metal particles are sprayed and rapidly solidified to produce powder, if an attempt is made to obtain a powder having a large particle size in order to solve the above-described problems, the effect of quenching will be reduced. It becomes an alloy with poor strength and toughness.

In addition, when attempting to produce an aluminum alloy powder having a large particle size by another granulation method, a binder is usually required. When a binder is used, it is difficult to completely remove the binder, and it is not possible to obtain mechanical properties equivalent to those of an aluminum alloy powder obtained by rapid solidification.

An object of the present invention is to solve such a conventional problem and to provide a method for producing an aluminum alloy powder for forging which is excellent in fluidity, does not enter a gap of a mold, and hardly soars as dust. .

[Means for Solving the Problems] In the production method of the present invention, a step of once mechanically molding a raw material powder of an aluminum alloy obtained by a rapid solidification method to obtain a powder molded body; Pulverizing into a powder again, and classifying the powder after the pulverizing step to obtain a fine powder having an average particle size of 80 μm or more and 44 μm or less.
% Powder.

The present invention further includes a step of annealing the powder after the classification step at a temperature of 150 ° C. or more and less than 400 ° C.

In the present invention, the forming of the raw material powder of the aluminum alloy can be performed, for example, by rolling into a plate or a rod. The plate-like or rod-like shaped body thus obtained is pulverized and classified to obtain a powder having a particle size distribution having an average particle size of 80 μm or more and a particle size of 44 μm or less and less than 30%.

[Operation] In the production method of the present invention, the raw material powder of the aluminum alloy is formed by a powder rolling device or the like, and the powders are once mechanically combined. Next, the compact is pulverized and classified so as to have a predetermined particle size distribution. The fine powder or coarse powder removed by this classification is again put into a powder rolling device or the like together with the raw material powder and can be used as a raw material.

As described above, in the present invention, the granulation is performed dry and cold, so that a powder having a predetermined particle size distribution can be obtained without impairing the microstructure in the powder obtained by the rapid solidification method as the raw material powder. Further, since the binder is not used in the manufacturing method of the present invention, the powder surface is not contaminated by the binder, so that the mechanical properties are not deteriorated, and the step of removing the binder is unnecessary.

In the classification step in the production method of the present invention, classification is performed so that the average particle size is 80 μm or more. The reason for this is
If the average particle size is less than 80 μm, the fluidity cannot be improved. Also, the particle size of 44 μm or less is set to be less than 30%. The reason is that 30%
This is because, when the above occurs, many particles enter into the gaps of the mold and the seizure of the mold becomes remarkable.

Further, the present invention further includes a step of annealing the powder after the classification step at a temperature of 150 ° C. or more and less than 400 ° C. The reason why the annealing temperature is 150 ° C or more and less than 400 ° C is that
If the temperature is lower than 150 ° C., the powder hardness cannot be reduced by cold working after granulation, and the molding density of the mold decreases. Is saturated, and the strength of the material is likely to be impaired.

[Example] As a raw material powder, Al- having an average particle size of 40 μm or less was used.
Using Si alloy powder, this is powder-rolled, width 50mm thickness 3m
m long plates were continuously formed. This compact was pulverized to obtain a powder having a particle size distribution as shown in FIG. FIG. 1 also shows the particle size distribution of the raw material powder.

This crushed powder is -30mesh using a sieve, + 325m
The granulated powder was manufactured by sieving to esh. Table 1 shows the flowability and apparent density of the granulated powder and raw material powder.

As is evident from Table 1, the granulated powder produced according to the present invention shows better flowability than the raw material powder.

A lubricant was mixed with the granulated powder thus obtained, and 4t
It was formed into a cylindrical shape having a diameter of 11.3 mm and a height of 10 mm under a constant pressure of on / cm ² . Further, as a comparison, a lubricant was mixed with the raw material powder under the same conditions and molded into a similar cylindrical shape. The punching load (kg), molding density (g / cm ³ ), and Rattler value (%) of the obtained granulated powder and raw material powder compact were determined by the second method, respectively.
FIG. 3, FIG. 3, and FIG. The results of the above experiment are shown as "no annealing" in each figure.

As is clear from FIGS. 2, 3 and 4, it can be seen that the granulated powder produced according to the present invention exhibits superior load, compact strength and compressibility as compared with the raw material powder.

Using a molding die as shown in FIG. 5, a stepped molded body was produced from the granulated powder obtained as described above. Fifth
In the figure, 1 indicates an upper punch, 2 indicates a lower punch, 3 indicates a molded body, and 4 indicates a die.

The density (g / cm ³ ) of each part of the obtained molded body was measured, and the density of each part was shown in FIG. 6.
As shown in the figure, the molded product was molded using a mold, and the density distribution of each part of the obtained molded product was measured and shown in FIG.

As is clear from the comparison between FIGS. 6 and 7, it can be seen that the granulated powder obtained according to the present invention gives a compact having a more uniform density distribution than that of the raw material powder.

In addition, the compact obtained from the granulated powder and the raw material powder was hot forged, and a tensile test piece was taken out from each part of the forged body,
The tensile strength was measured and the results are shown in Table 2.

As is clear from Table 2, the forged body using the granulated powder manufactured according to the present invention has less variation in the tensile strength than the forged body from the raw material powder.

Next, the granulated powder obtained by pulverizing and classifying the compact of the raw material powder as described above is annealed at 350 ° C. for 2 hours, and at a constant pressure of 4 ton / cm ^{2 in} the same manner as described above, with a diameter of 11.3 mm. Then, a cylindrical molded body having a height of 10 mm was molded, and the molding load (kg), molding density (g / cm ³ ), and tetra value (%) of the molded body were measured. , FIG. 3, and FIG. In addition, in each figure, it is shown as "with annealing".

As is clear from FIGS. 3 and 4, it is understood that by further annealing the granulated powder, more excellent compressibility and strength of the compact can be obtained.

[Effects of the Invention] As described above, since the aluminum alloy powder obtained according to the production method of the present invention has excellent flowability, the variation in the density in the compact and the variation in the strength in the forged body are smaller than before. Become. In addition, since the amount of the powder having a size of 44 μm or less is less than 30%, the risk of the mold entering the gap of the mold and seizing as in the related art is reduced. Further, dust is hard to fly, which is preferable from the viewpoint of safety and hygiene. Furthermore, since it is a dry and cold granulation method, a forged body having excellent mechanical properties is provided.

[Brief description of the drawings]

FIG. 1 is a diagram showing the particle size distribution of the raw material powder used in the embodiment of the present invention and the powder obtained by molding and grinding the raw material powder. FIG. 2 is a diagram showing a load for removing a compact of a granulated powder and a raw material powder obtained in an example of the present invention. FIG. 3 is a diagram showing a molding density of a compact of granulated powder and raw material powder obtained in an example of the present invention. FIG. 4 is a diagram showing the Rutler value of the compact of the granulated powder and the raw material powder obtained in the example of the present invention. FIG. 5 is a cross-sectional view showing a die formed by press molding in the embodiment of the present invention. FIG. 6 is a diagram showing a density distribution of a granulated powder compact obtained in an example of the present invention. FIG. 7 is a diagram showing the density distribution of the compact of the raw material powder used in the embodiment of the present invention. In the drawing, 1 indicates an upper punch, 2 indicates a lower punch, 3 indicates a molded body, and 4 indicates a die.

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Yusuke Kotani 1-1-1, Koyokita, Itami-shi, Hyogo Prefecture, Japan Itami Works, Sumitomo Electric Industries, Ltd. No. 1-1 In Itami Works, Sumitomo Electric Industries, Ltd. (72) Inventor Toshihiko Kaji 1-1-1, Koyokita, Itami-shi, Hyogo Prefecture Examiner, Itami Works, Sumitomo Electric Industries, Ltd.Akihiro Kitamura (56) References JP-A-1-139701 (JP, A) JP-A-64-83631 (JP, A) JP-A-59-162201 (JP, A) JP-A-63-203701 (JP, A) JP-A 64-11764 (JP, A) 3rd Edition Iron and Steel Handbook Volume ▲ V ▼ (Casting, Forging, Powder Metallurgy), Section 16.2.1.a, page 463 (Oct. 11, 1982, Maruzen Co., Ltd.) (58) Fields surveyed (Int. Cl. ⁷ , DB Name) B22F 1/00 B22F 9/04

Claims (1)

(57) [Claims] A step of once mechanically forming a raw material powder of an aluminum alloy obtained by a rapid solidification method to obtain a powder compact; a step of pulverizing the powder compact to obtain a powder again; Classify the powder after the pulverization process, the average particle size is 80μm
A method for producing an aluminum alloy powder for forging, comprising: a step of converting fine powder having a size of not less than 44 μm and less than 30%; and a step of annealing the powder after the classification step at a temperature of 150 ° C. or more and less than 400 ° C. .