JPS6386831A - Manufacture of working stock of aluminum-base sintered alloy - Google Patents

Abstract

PURPOSE:To contrive to enlarge product size, to reduce the number of stages, and also to improve workability, by forming a green compact by using, among powdery raw materials, Mg, Zn, Si and Cu in the form of pure metal powder and also using other additive elements in the form of alloys with Al and then by sintering the above green compact. CONSTITUTION:As a part of the powder raw materials for compaction, pure- metal powders of one or more elements among Mg, Zn, Si, and Cu are used and, as to the alloying elements to be added among Fe, Cr, Co, Ni, Mn, Ti, Zr, V, Ce, Sn, Pb, and Li, they are added to the powdery raw materials in the form of alloy powders previously alloyed with Al. The above powdered raw materials are compacted, and the resulting green compact is sintered at about 500-600 deg.C in vacuum or in an inert atmosphere. Moreover, it is desirable that compaction is carried out so that density ratio of the green compact is regulated to >=90$%. In this way, the necessity of sealing green compacts in a vessel can be obviated and, as a result, working stocks of Al-base sintered alloy can be manufactured at a low cost.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application This invention relates to a method for producing a material for processing in order to produce a rolled or forged material such as a rolled or extruded material made of an aluminum-based sintered alloy. It is something.

Conventional technology In general, when manufacturing aluminum sintered alloys such as rolled materials, extruded materials, or forged materials, conventionally, an alloy powder is created by an atomization method in air or an inert gas atmosphere, and then processed as necessary. After pumping, the alloy powder is compressed for 1 minute using a press to form a compact, and then the compact is sealed in a pre-prepared aluminum alloy container (can), and Depressurize the fillet and heat it to degas while keeping it in a vacuum, press it with a rough press to make a fillet for straining, then cut off the container covering the outer surface of this fillet, and then extrude it. Usually, processing such as rolling or forging was performed.

In such conventional methods, degassing after the green compact is sealed in a container prevents blistering during heat treatment after processing, and also prevents the powder from bonding with each other during hot pressing. In other words, without degassing, the moisture combined with or adsorbed on the oxide formed on the surface of the grain will not be removed, making it difficult to process. It remains in the form of hydrogen in the material afterwards, causing blistering during heat treatment.Also, unless descaling is performed, the surface oxide of the powder will remain strong, and the surface oxide will cause the powder to bond with each other during hot pressing. This prevents the bonding (sintering) of the

On the other hand, the purpose of applying iζ1~press in the conventional method described above is to ``deform the powder by compressing it into light to destroy the oxides on the powder surface, and to prevent the bonding (sintering) of the powders. The aim is to allow sufficient progress to give the material the strength to withstand deformation during subsequent processing.

Problems to be Solved by the Invention In the conventional method as described above, pressure (because it requires a step of sealing the fragments in a container, the container ultimately
This limits the size of the product that can be pressed, making it difficult to make the product larger, and requires a process to insert the green compact into the container and a process to cut and remove the container after pressing. The number of steps involved is large, which inevitably leads to high costs. In addition, as mentioned above, the container limits whether it is nice or not, so during processing, it is necessary to extrude, roll, or forge one by one, which results in low workability and is particularly unsuitable for continuous processes such as rolling. It was.

This invention was made in view of the above circumstances, and aims to increase the size of the product, reduce the number of steps, improve work efficiency, and reduce costs by omitting the need to enclose the compacted powder in a container. (h of aluminum-based sintered alloy made to
The purpose of this invention is to provide a method for producing materials for U-tech development.

Means for Solving the Problems As mentioned above, when manufacturing materials for processing aluminum-based sintered alloys without enclosing the green compact in a container, it is possible to achieve the same or better performance than the conventional method, especially The problem is how to obtain a material that has good hot HO processability. In other words, in the conventional method, as mentioned above, degassing while the green compact is sealed in a container, followed by hot pressing, prevents the occurrence of blisters during heat treatment and sufficiently bonds the powders together. It has a great strength to withstand deformation during hot 7J rolling process (q), but how can such degassing and hot pressing be done if the sealing of the green compact in the container is omitted? The important issue is whether to do so, or how to achieve an effect equivalent to the effect caused by them.

Therefore, the inventors of the present invention have conducted various experiments and studies, and as a result, the blending form of the raw material powder for pressure 1 minute is determined depending on the type of alloying element to be added, that is, whether it is used as a pure metal powder or as an alloy powder. If the powder is properly selected and the green compact is sintered in a vacuum or inert atmosphere after compaction, the hot θ0 machining performance is equal to or higher than the conventional method of degassing and hot pressing. He discovered that this could be done in a variety of ways, and came up with this invention.

Specifically, the aluminum-based sintered alloy of the present invention is manufactured by: A method for producing an aluminum-based sintered alloy containing one or more elements selected from among Mg, Zn, 3i, and Cu;
e, Cr, Co, [\11. \=In, Ti, Zr, V
, Ce, Sn, Pb, and Ll as alloying elements. As part of the raw material powder,
1 selected from MCI, Zn, Si, and Cu
In addition to using pure metal powder of flat or two or more elements, Fe, Cr, Co, N:, ~In, Ti, Zr, V
, Ce, Sn, Pb and Ll.
Separation source 1116) Calories are added to rice, and the raw material (4) powder is pressed into powder to create a green compact, and then the green compact is heated to 7 J[] in a vacuum or in an inert gas to sinter it. It is characterized by tying.

Here, the density ratio (ratio to true density) of the compacted powder is 9QC3
It is desirable to perform this so that the number is 6 or more. Further, sintering is preferably carried out at a temperature within the range of 500 to 600°C.

Function In this invention, first, the form of the raw material powder for powder compaction is
It is necessary to select the alloying element appropriately depending on the type of alloying element added. In other words, in the past, it was common practice to first alloy all of the alloying elements 1 and 2 with the alloying elements 2 and 2, and then use the alloy powder obtained from A1 to Mize as the raw material for powder compaction. In such an alloy powder, the alloy concentration is the same in all powder particles, and therefore, during sintering, it is difficult to bond the particles together by diffusion using the alloy temperature difference.Therefore, in this invention, in particular, the diffusion rate For elements that have a fast rate of oxidation, they can be used in the elemental form as pure metal powder, used as part of the raw material powder for powder compaction, mixed uniformly and compacted, and then sintered to promote sintering. Among the alloying elements normally used in aluminum alloys, N・iQ (magnetic screw 1 cum)
, Zn (zinc), Si (silicon), and Cu (copper) all have fast diffusion rates, so they can be used as pure metal powders to form A
l 111) By mixing powder and powder with 2 alloy powder and compacting, the elements of the pure metal powder quickly diffuse into Al powder particles and A1 alloy powder particles during sintering, and
Al powder particles through pure metal powder! Bonding between alloy powder particles also progresses rapidly.

However, it is not necessary to use the entire amount of all the elements to be added behind M CJ, Zn, Si, and Cu as pure metal powder, and it is possible to use only some of the elements as pure metal powder, or It is permissible to use only an amount corresponding to a part of the additive force Du as a pure metal powder out of the total addition amount, and use the rest as an alloy powder with Al. However, the larger the amount of powder used as pure metal powder, the greater the effect of promoting the bonding between Z0 ends, so usually ~1 g, Z
It is desirable to use the permanent elements of n, Si, and Cu to be added as pure metals.

In addition, Fe (iron), Cr (chromium), Go (cobalt), ~In <manganese), Ti (ditane>), Zr (zirconium), ■ (vanadium), Ce
Elements with a slow diffusion rate such as (cerium), Sn (tin), pb < target), etc., do not diffuse sufficiently during sintering even if they are used as pure metals (lithium), and Li (lithium) Because it is active, it is dangerous to use it as a pure metal powder;
Therefore, when producing an aluminum-based sintered alloy containing these elements, Al
It is used as an alloy powder alloyed with.

As described above, in the present invention, one or more alloying elements behind ICI, zn, sr, and CU, and Fe, Cr, and C
o, N i , ~1n, T + , Zr, V, Ce.

In producing an aluminum-based sintered alloy hot working material that simultaneously contains one or more alloying elements among Sn, Pb, and Li, at least a portion of the 110 alloying elements is prepared as pure metal powder. The latter alloying element must be used as an alloying element that has been previously alloyed with Δ.

The raw material powder as described above is compacted as it is without putting 1q in a container (heap), and a part of the powder compact is formed.

This powder compacting method can be either a method of compacting the powder in a mold using a press, or a method of directly dropping the powder from a popper between rolls and obtaining a sheet-shaped powder compact with the rolls. It's okay. The former die press method is suitable when extrusion or forging is used as a processing method, and the latter roll press method is optimal when rolling is used as a processing method. Here, in order to promote the bonding between powders during sintering after compaction, the density of the compact should be 90-6 or more, preferably 95% or more of the true density in the compaction process. It is desirable to compact the powder into powder.

Sintering after compaction must be performed in a vacuum or in an inert atmosphere. By sintering in a vacuum or inert atmosphere, moisture between the powder particles in the green compact is removed at the beginning of sintering, and the sintered body undergoes hot heating [[[blistering] during post-processing heat treatment. Occurrence can be prevented. Inert atmospheres include nitrogen, argon, helium, aqueous,
Alternatively, it is desirable to use a mixture of them.

In addition, if the heating temperature is too low, diffusion will be insufficient and the alloy will not be uniformly formed, while if the temperature is too high, a large amount of liquid phase will occur. It becomes impossible to achieve finer particles and increase in solid solution. Therefore, it is generally preferable to apply a sintering temperature within the range of 500 to 600°C.

The sintered body obtained in the above manner is a material for hot or cold processing, and the sintered body is subjected to arbitrary processing such as extrusion, rolling, and forging to produce a final product. . Here, it is desirable to perform heating for hot processing in the same atmosphere as during sintering in order to prevent re-oxidation of the sintered body and adsorption of moisture. It is preferable to carry out hot loe without cooling the material.

In addition, after sintering, when hot working is performed by cooling once and then reheating, the atmosphere of the re-BO heat is set to be a vacuum or an inert atmosphere similar to the atmosphere during sintering. Hey, extrusion, rolling,
During hot processing operations such as forging, the sintered body is exposed to the atmosphere, or these operations are completed in a short period of time.
There are few problems such as re-oxidation.

As mentioned above, the blending form of the raw material powder for compacting was selected at the beginning of the week, and one or more of Zn, Si, and Cu was used as pure metal powder, and Fe, Cr, and C were used as pure metal powder.
o, N i , ~1n, r*, zr, v, Ce, Sn,
Of Pb and li, 8 alloying elements should be added in advance! By using the powder as an alloy powder alloyed with I'i and performing sintering in a vacuum or in an inert atmosphere, it is possible to encapsulate the I'i substitute body in a container and then remove the scum and hot press as in the conventional method. Even if omitted, (
It is possible to sufficiently promote the bonding between the 5-terminals and provide strength equivalent to 1.1 to withstand deformation during processing, and also to prevent the occurrence of blistering at the heat treatment opening after processing.

Examples [Example 1] As shown in Table 1, three types of powder (~α1~Nα
3) was prepared as a raw material powder for compacting, and pressed into a sheet with a thickness of 6 mIn using a press using a mold so that the compactness ratio of the compact was 85%, 90%, and 95%, respectively. Powder molded. Next, for the green compacts of each density ratio, the sintering temperature was set to 450°C, 1500°C, 1550°C, 1600°C, 1625°C.
Sintering was carried out at various temperatures of °C for 1 hour each in a nitrogen stream. Then, each sintered body was heated to 410 to 44 mm in the same nitrogen stream.
It was heated to a temperature of 0°C and hot rolled from a plate thickness of 6 m to 2#. Note that the rolling reduction rate during each hot rolling was 10%.

In order to evaluate the hot workability, the results of investigating the degree of edge cracking during hot rolling are shown for each powder\01 to NQ3.
Tables 2 to 4 show the green compact density ratio and the FA temperature. In addition, in Tables 2 to 4, )A'',
"B" and [CJ] respectively indicate the degree of edge cracking during hot rolling as follows.

A: Hardly any ear cracking B: Moderate ear cracking C: Ear cracking 1 large Table 1 □° German pot m eura 1 1
．． 6 1 Table 2: Hot workability of sintered body using powder N091 Table 3: Hot workability of sintered body using powder N0.2 Table 4: Sintering using powder NQ3 As is clear from Tables 2 to 4, 7n, Mg, CL
J is used as a pure metal, and Co is an alloy (in the case of Nα3 powder used as a sintered body, there is less edge cracking during rolling), and in the case of other powders\α1 and Nα2. This was necessary because the hot H0 workability was better compared to the previous one.

First, when the density ratio of the green compact was set to 90% or more for Nα3 powder and the powder was sintered at 500 to 600°C, it showed extremely excellent hot working performance.

[Example 2] The powders \04 to N011 shown in Table 5 were prepared as raw material powders for loaf leveling, and each was rolled with a cross-thickness of 2.5 m so that the density ratio of the green compact was 95%. [Shi] was pressed into a flat powder. Then, for each pressure body, 560
The sintered body was sintered at ℃ for 1 hour and then heated at 41℃ in vacuum.
It is heated to 18 degrees from 0 to 440℃;
It was hot rolled to 171 m. Note that the rolling reduction rate in each hot rolling was 10%.

The ear υ of each sintered body made during hot rolling] Reno! The results shown in Table 5 were obtained. In addition, evaluations A, B, and C of “degree of occurrence of ear swelling” in Table 5 are based on the second
This is the same as in the case of FIGS. This result also shows that when the blended form of the present invention is used as the raw material powder for powder compacting, the hot workability is good.

Table 5 ■U Mouth □□□□□□□□□■ □□1 □-4 JtU+U (9U (24N11%Ll19 1100
．． Effects of the OI Ci Invention As is clear from the above explanation, according to the method of this invention, it is possible to save the sealing of the compact into a container (can) and improve hot or cold workability. It is possible to obtain the basic skills for processing aluminum sintered alloys. = Products can be made larger without being limited by containers, and the process of enclosing the green compact in the container and removing the container after sintering is no longer necessary, so the number of steps is significantly greater than before. This makes it possible to improve productivity and reduce costs, and it also makes it possible to manufacture continuous materials, making it possible to apply I'J2 hE processes such as rolling as a method for the next process. (Is it because of the effect of something like that?)

Claims (3)

[Claims] (1) One or more elements selected from Mg, Zn, Si, and Cu, and Fe, Cr, Co, and Ni
, Mn, Ti, Zr, V, Ce, Sn, Pb and Li
When manufacturing materials for processing aluminum-based sintered alloys containing one or more elements selected from the following as alloying elements, Mg is used as part of the raw material powder for compaction. ,Zn,S
Using pure metal powder of one or more elements selected from i, and Cu, as well as Fe, Cr, C
The alloying elements to be added among O, Ni, Mn, Ti, Zr, V, Ce, Sn, Pb, and Li are added to the raw material powder for compaction as an alloy powder alloyed with Al in advance, and the A method for producing a material for processing an aluminum-based sintered alloy, which comprises: creating a compact by compacting powder, and then heating and sintering the compact in a vacuum or in an inert gas. . (2) The method for producing a material for processing an aluminum-based sintered alloy according to claim 1, wherein the compacting is performed so that the density ratio of the compact is 90% or more. (3) The method for producing a material for processing an aluminum-based sintered alloy according to claim 1, wherein the sintering is performed at a temperature within a range of 500 to 600°C.