JPS6184343A - Manufacture of member made of aluminum alloy - Google Patents

Abstract

PURPOSE:To manufacture the titled member with low cost from Al alloy powder material with superior raw material yield, by press molding Al alloy powder difficult to be hot forged, then, hot extruding and hot forging said body under specified conditions. CONSTITUTION:Al alloy powder having compsn. difficult to hot forging is compacted to >=70% density ratio. The compact is heated to 240-430 deg.C, then hot extruded to a formed part 1. Thereat, a sectional area (that in the direction at right angle to extruding direction) S1 of the part 1 is made to 75-95% of an outer projected area S2 of a formed part 4 obtd. by next hot forging. Next, the part 1 is cut at a plane 2 to a preformed part 3 having a thickness t1, then said part is heated to forging temp., and hot forged by 5-25% draft to manufacture the part 4, then, flush 6 is removed to obtain the completed part.

Description

[Detailed Description of the Invention] Lt-Upper Stage 5 Mj131 The present invention relates to a method of manufacturing an aluminum alloy member by a powder forming method, and particularly relates to a method of manufacturing an aluminum alloy member having a composition range in which hot forging is difficult. be.

In internal combustion engines for automobiles, aluminum alloy materials are actively used to reduce the weight of the vehicle body, and in particular, moving parts such as connecting rods, rocker arms, and pistons are made of aluminum alloy material. is also effective in reducing inertial force. However, since such moving parts are used under harsh conditions at high temperatures, it is necessary to use material II with good heat resistance, high scratch marks, and high Young's modulus. Powder metallurgy products, which allow alloying elements to be added with a large degree of freedom, are being adopted.

As a material for such powder metallurgy products, the present applicant proposed in Japanese Patent Application No. 58-239429 that the heat resistance, abrasion resistance, Young's modulus, and heat insulation properties are improved by adding multiple types of elements to aluminum. An aluminum alloy with high iron content was proposed to improve the quality of the product.

In order to obtain a specified molded product from aluminum alloy powder with such a composition, it is necessary to perform hot forging (G1), but conventional methods for processing aluminum alloys with good malleability In the forging method, the reduction rate was set sufficiently high to increase the forging efficiency, resulting in a thick t1 flash, and the yield was at most 55%, making it difficult to adopt conventional processing methods.

The reason is that, firstly, in aluminum alloys containing iron,
This is because a nail-like crystal compound called FeAes is generated and this inhibits malleability, so alloys with Fe≧10@hang% have poor forging workability, and a decrease in yield due to the occurrence of cracks is also a problem. Second, waste containing large amounts of iron (
This is because scrap materials have low reuse value.

Completely closed die forging may be adopted as a processing method to improve yield, but when processing non-standard or irregularly shaped products, the mold structure becomes complicated and the life of the mold decreases. At present, this method has not been put into practical use because the product cost increases.

11] Fuchi Tanen 11 Sushi Tamaraichi m111 The present invention was created with this technical background in mind, and its aim is to produce an aluminum alloy with a composition range that is difficult to hot forge. The goal is to obtain a final forged product from powder at a high yield.

The 11IJ manufacturing method of aluminum alloy members according to the present invention involves compacting aluminum alloy powder with a composition range that is difficult to hot forge to a density ratio of 70%, and heating the compacted product to a temperature of 240 to 430°C. The extruded product is heated and hot extruded so that the cross-sectional area of the extruded product becomes 75 to 95% of the external projection of the final forged product, and the extruded product is rolled at a reduction rate of 5 to 95%.
It is characterized by hot forging at 25%.

In order to obtain a molded product by the hot die forging method using aluminum alloy powder with poor hot forging formability, the reduction ratio (reduction ratio R% - (material wall thickness - molding wall thickness) xlOO) during die forging is required.
/material thickness) is preferably made small. By reducing the rolling reduction rate, the amount of flash is reduced and cracks are less likely to occur, so an improvement in yield can be expected.

The present invention was devised from such a point of view, and in the first step, aluminum alloy powder is heated so that the density ratio (the ratio between the powder density and the true density of a substance having the same composition as the green compact) is 70
Powder compaction (cold isostatic press molding method or mold liquid compression molding method) is performed so that the powder is less than % I-. Here, the density ratio is 70
% or more because if it is less than 70%, it will be difficult to handle the molded product for the next process. However, in consideration of moldability in this step, it is preferably 85% or less.

In the next second step, the powder molded product is heated to 240 to 430°C, and then hot extrusion processing, which is the first stage processing, is performed in the temperature range, for example, as shown in Figure 1. A molded product (for Nexbun Grotto) 1 is obtained. At that time, the cross-sectional area (cross-sectional area in the direction perpendicular to the extrusion direction) Sl of the extruded product 1 is the forged product 4 to be obtained by hot die forging, which is the second stage of processing (see Figure 3). 15 to 95% of the external projected area S2. Heating temperature 240~4
The reason for setting it at 30°C is that if it is less than 240°C, the deformation resistance will be large and extrusion processing will be difficult, and if it exceeds 430°C, the structure will become coarse and the desired mechanical properties of the product will not be obtained. be. In addition, the heating element is particularly 30
The temperature is preferably 0 to 400°C. The reason is 300
Below ℃, in alloy powders with increased iron content,
Powdered hardwood is high<1. The sinterability deteriorates due to
When the temperature exceeds 0°C, if alloy powder with a large number of added elements is used, the eutectic temperature decreases, causing burning.
) is likely to occur, resulting in poor sinterability. Also,
The reason why the area ratio (S1/5t) This is because it is necessary to maintain the shape of the acute angle portion during extrusion processing, and the extrusion molded product 1 is likely to be cracked or curved, making processing difficult.

In the third step, the extrusion molded product 1 is cut at 2 to obtain a preformed product 3 having a wall thickness of t1.

This cutting direction is perpendicular to the flow line of the material along the extrusion direction, and the forging reduction direction in the next step coincides with the flow line direction, so forging formability is extremely good.

In the fourth step, after heating to the forging temperature, the reduction rate ((1
:t T2) Reduce the reduction rate to 5-2
The reason for setting it to 5% is that if the indentation ratio is less than 5%, a high yield can be expected, but the free flow to the corners of the mold will be insufficient and it will be difficult to form the flesh 1 & crevice 5. This is because if it exceeds 25%, the yield decreases due to the occurrence of cracks and an increase in sagging.

Next, the fludge rollers protruding from the outer periphery of the forged product 4 are removed to complete the process.

A desirable composition of the aluminum alloy powder used to obtain a forged molded product having a strong stone special bamboo excellent as an internal combustion engine part through such a process is as follows.

4≦Fe≦33 Kawama%, 10≦81≦30% by weight
08≦Cu≦7.5% weight, 0.5≦H (1≦3
55 Weight balance - AJ The reasons for adding each element will be described below.

(a) Fe: Iron is necessary to improve high temperature strength, heat insulation and Young's modulus. However, if it is less than 4% by weight, the culm will have some high-temperature strength [but the high-temperature strong acid will be insufficient, and if it exceeds 33% by weight, the density will increase and weight reduction will be impaired, and in addition, hot extrusion will be difficult. Formability deteriorates during processing, hot forging, etc.

Further, the Young's modulus improves as the time between additions of iron increases, but in consideration of the density, the time between additions of iron is limited to the above upper limit.

(b) Si: Silicon is effective in compensating for the lack of wear resistance caused by the addition of iron alone and in improving Young's modulus.

However, if it is less than 10% by weight, the wear resistance cannot be improved, and if it exceeds 300% by weight, the moldability deteriorates and cracks are likely to occur in the structural member. Like iron, the Young's modulus improves as the amount of silicon added increases, but it is limited to the above-mentioned upper limit in consideration of formability.

(C) Cu: Copper is added to compensate for deterioration in sinterability and formability caused by addition of iron and silicon. However, 0.8
If it is less than 7.5% by weight, there is no effect of improving sinterability or strength by heat treatment, and if it exceeds 7.5% by weight, high-temperature strength is impaired.

(d) No: Magnesium is added for the same purpose as copper; if it is less than 0.5% by weight, there is no effect of improving sinterability or strength by heat treatment, and if it exceeds 3.5% by weight , high temperature strength is inhibited.

In addition to the above elements, at least one type of manganese (l(n)), curved lead (Zn), and lithium (1-i) is added at 1.5<H
n〈5.0 heavy goods%, 0.5≦'b5. It is effective to add within the range of 0 weight percent.

The reason for its addition is as follows.

(e) on: In the production of atomized powder, it is necessary to set the cooling rate of aluminum alloy powder to the maximum, but if mass production is considered as
The limit is °C/sec.

In this cooling rate range, if Fe≦6%, Al
The 1-Fe-3i intermetallic compound is sufficiently divided in the hot extrusion process, and the precipitation form of the compound becomes 11-shaped, increasing hot deformation resistance and making high-speed hot forging impossible.

Manganese is effective for controlling the precipitation form of the intermetallic compound. That is, by adding manganese in the above specified phase, the 11-like ^13 [e phase and J: and β-All, instead of the FeSi phase.

Massive A Jl, (Fe, Hn) phase and (X -AJ
,, (Fe, Hn).

The Si phase is preferentially precipitated, thereby improving high-speed hot forging properties and improving the strength of the structural member.

However, if it is less than 1.5% by weight, the above effect cannot be obtained, and 5% by weight or less cannot be obtained.
．． If the weight is 0 or more, hot deformation resistance increases and high-speed hot forging becomes difficult.

(f) Zn: In order to improve the strength of a member used under temperature conditions of 200°C or less, it is necessary to add 16
It is effective to perform a treatment to utilize the solution precipitation effect of silicon, copper, and magnesium.

Zinc is added to improve the solution precipitation effect. However, if it is less than 0.5% by weight and 1% by weight, the above effects cannot be obtained, and if it exceeds 10% by weight, hot deformation resistance increases and high-speed hot forging becomes difficult.

Conventionally, when zinc is added as a right-handed element, the silicon contained in the aluminum alloy is treated as an impurity. However, in the alloy of the present invention, by applying powder metallurgy during its manufacture, the silicon contained in the aluminum alloy is treated as an impurity. A material for extrusion processing with a density ratio of 15%, a diameter of 225 mm, and a length of 300# is molded by compression molding.

In the cold isostatic press molding method, alloy powder is placed in a rubber tycope and 1.5 to 3. Molding is performed under hydrostatic pressure with a culmness of Ot/c#i, and in mold compression molding, the alloy powder is placed in the mold and the molding temperature is 1.5 to 3. Ot
,/ff1Pi! Shaping is done under pressure from hemp.

Each extrusion material was placed in a soaking furnace with an internal temperature of 350°C and held for 10 hours, and then hot extrusion was performed on each extrusion material (cross-sectional area -8, )
Build a lit.

In this case, the extrusion method is direct extrusion (forward extrusion),
Either indirect extrusion or backward extrusion may be used, but the extrusion ratio must be 5 or more. If the extrusion ratio is less than 5, it is not preferable because the variation in strength becomes large. The temperature of the extrusion material is set at 240 to 430°C. 24
When the temperature is lower than 0°C, the deformation resistance of the material increases and the extrusion load [1] deteriorates, and when the temperature exceeds 430°C once, the structure becomes coarse and a high -13-8 rJ strength product cannot be obtained. After the extrusion process, the forging material is cooled at a predetermined cooling rate by air cooling or water cooling.

After that, each forging material was heated to 460-470°C,
The forging material was subjected to high-speed hot forging at a rolling reduction ratio R using a crank press with a processing speed of 75 m/Sec (almost the same processing speed as duralumin forging).

Table 1 shows examples of the present invention that were processed as described above.
■、■、Conventional forging method Nite、I、II、■、■、■
Example 1, it, in which alloy powders corresponding to
This is a comparison of iii, iv, and v.

In the method of the present invention, the ratio of the cross-sectional area S1 of the forging material (extrusion molded product) to the external projected area S2 of the forged product is
This is higher than that of the conventional method, and therefore the forging pressure F ratio R is lower than that of the conventional method. As a result, with the conventional method,
It can be seen that while cracks occurred in samples No. 11, iii, and iv, no cracks occurred in the method of the present invention, and the yield was significantly improved.

Departure! ! [1st Sung Dynasty] As is clear from the explanation above, according to the method of the present invention, even if aluminum alloy powder with a composition range that is difficult to hot forge is used, cracks are almost never caused during hot die forging. , high yields can be expected and cost reductions can be achieved.

[Brief explanation of drawings]

Figure 1 is a perspective view of an extrusion molded product which is an intermediate molded product when molding a neck rod according to the method of the present invention, and Figure 2 is a perspective view of a preformed product obtained by cutting the extrusion molded product to a predetermined thickness. FIG. 3 is a perspective view of a forged product (with a fludge) obtained by hot die forging the preform. DESCRIPTION OF SYMBOLS 1... Extruded product, 2... Surface, 3... Preformed product, 4... Forged product, 5... Lightening part, 6...
flash.

Claims (1)

[Claims] Aluminum alloy powder with a composition range that is difficult to hot forge,
The compacted powder product is heated to a temperature of 240 to 430°C to perform hot extrusion processing, and the cross-sectional area of the extruded product is changed to that of the final forged product. A method for manufacturing an aluminum alloy member, characterized by hot forging to a shape of 75 to 95% of the external projected area, and then hot forging at a reduction rate of 5 to 25%.