JP2000109944A - Wear resistant and high strength aluminum alloy molded body, its production and cylinder liner composed of the molded body - Google Patents

Abstract

PROBLEM TO BE SOLVED: To produce a high strength aluminum alloy molded body having wear resistance and high deforming performance and capable of molding complicated ones, to provide a method for producing it and to provide a cylinder liner composed of the molded body. SOLUTION: This molded body is composed of an aluminum alloy having a compsn. contg., by weight, 17 to <27% Si, 0.3 to <5.0% Cu, 0.2 to <2.0% Mg, and the balance Al with inevitable impurities, and in which the average particle size of Si particles distributed into the matrix is 1 to <5 μm, and, by subjecting the aluminum alloy stock to extrusion molding into a shape in which plural cylindrical bodies are arranged, the wear resistance thereof can be secured by the Si particles, moreover, its deforming performance can be maintained to a high degree, and even the one in which cylinder liners are plurally connected can be molded.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wear-resistant, high-strength aluminum alloy compact, a method for producing the same, and a cylinder liner made of the compact.

[0002]

2. Description of the Related Art In recent years, in a passenger car engine, an aluminum alloy has been used for a cylinder block in place of cast iron. However, in order to secure wear resistance of a sliding surface with a piston, a cylinder block is required. It is usual that a cast iron cylinder liner is cast inside. However, improvement of fuel efficiency has become an increasingly important issue from the viewpoint of preservation of the global environment, and attempts have been made to use aluminum alloys for cylinder liners.

[0003] The use of an aluminum alloy for the cylinder liner has the following advantages.
(1) Lighter than cast iron. (2) High thermal conductivity. (3) Since the coefficient of thermal expansion is the same as that of the cylinder block, the adhesion at the time of temperature rise is increased to provide an engine with excellent heat dissipation, and as a result, the combustion temperature can be increased, which also contributes to the purification of exhaust gas. . (4) Further, the coefficient of thermal expansion is the same as that of the aluminum alloy piston, and the clearance between the piston and the piston can be reduced. As a result, the consumption of lubricating oil can be reduced, the fuel consumption can be improved, and the noise can be reduced.

In order to obtain the above advantages, there have been proposed, for example, Japanese Patent Publication No. 6-37682 and Japanese Patent Publication No. 6-21309 as aluminum alloy materials for cylinder liners. The former is a molded body obtained by extrusion-molding a powder mixture obtained by adding a lubricant such as ceramic particles or graphite powder to a rapidly solidified aluminum alloy powder by powder metallurgy, and the latter is a component having adjusted components. It is a compact obtained by extruding rapidly solidified aluminum alloy powder by powder metallurgy.

[0005] These compacts are made of an aluminum alloy material that can be used as a cylinder liner. The above-mentioned advantages can be obtained in combination with a cylinder block made of an aluminum alloy. Is high and the deformation capacity is insufficient, so that cracks are likely to occur during extrusion molding. Therefore, for example, in these molded products, only one cylindrical cylinder liner can be manufactured by extrusion molding using a mandrel method. Absent. Accordingly, the engine block is manufactured by arranging cylinder cylinder liners made one by one in a required number of molds, and being manufactured by casting an aluminum alloy for the cylinder block, or by mounting the cylinder liner on a separately manufactured cylinder block. Is press-fitted.

In the engine block manufactured as described above, as shown in FIG. 5, the distance between the centers of adjacent cylinder liners, that is, the bore interval l _p is the bore diameter l ₁ +
Thickness 2l ₂ + thickness of cast aluminum alloy l ₃
Therefore, there is a problem that the engine cannot be downsized, and a high rigidity is required for the crankshaft.

To solve this difficulty, a method of reducing the bore interval l, as shown in FIG. 6, porthole scheme is more connecting cylinder liner a by extrusion molding by, to narrow the bore spacing l _h Possible (l _h <
l _p ). However, as described above, the conventional molded body has insufficient deforming ability, so that a plurality of cylinder liners a cannot be connected.

[0008]

SUMMARY OF THE INVENTION In order to realize the above-mentioned plural connection, the present invention is based on the above Al-Si alloy which has been conventionally proposed as an aluminum alloy material for a cylinder. It was made as a result of conducting various experiments and studies on the relationship between the cylinder and the extrudability. The purpose was to ensure high strength and abrasion resistance, as well as high deformability, and to connect multiple cylinder liners. Abrasion resistance, high-strength aluminum alloy molded body that can be molded even with complicated things such as
An object of the present invention is to provide a cylinder liner made of the manufacturing method and the molded body.

[0009]

Means for Solving the Problems In the course of the above experiments and examinations, the present inventors set the Si content in an Al-Si-Cu-Mg-based aluminum alloy to 17% or more and less than 27%, A material containing Mg in a predetermined range and rapidly solidified by spray forming to produce a material having a Si particle size of 1 μm or more and less than 5 μm, or a rapidly solidified powder produced by atomizing with air or an inert gas by powder metallurgy. Any material having a Si particle size of 1 μm or more and less than 5 μm has high abrasion resistance while maintaining high strength, and also has good deformability and therefore extrudability, so that a plurality of cylinder liners are connected. It has been found that extrusion molding can be performed even for a complicated one, such as the formation of the resin, and the present invention has been completed.

That is, according to the present invention, Si is 17% or more and less than 27%, Cu is 0.3% or more and less than 5.0%,
It has a composition containing 0.2% or more and less than 2.0%, with the balance being Al and unavoidable impurities, and the average particle size of Si particles distributed in a matrix of the composition is 1 μm or more and 5 μm or less.
Abrasion-resistant, high-strength aluminum alloy formed by extruding the aluminum alloy material into a shape in which a plurality of cylinders are juxtaposed.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION The significance of the alloy components in the present invention and the limited range thereof will be described.
17% or more and less than 27%, preferably 20% or more and 23% in aluminum alloy material (hereinafter simply referred to as aluminum alloy)
It is preferable to contain it in the range of less than. In this range, the hard Si particles are sufficiently dispersed in the aluminum alloy. For example, when this aluminum alloy is used for a cylinder liner, required wear resistance can be obtained. Si content is 17
%, The abrasion resistance becomes insufficient, and if it exceeds 27%, the deformability decreases. Therefore, the extrudability also deteriorates, and when the cylinder liner is extruded at an economical speed, cracks may occur.

Further, Si distributed in the matrix is
The average particle size of the particles needs to be in the range of 1 μm or more and less than 5 μm. For example, a cylinder liner cast into a cylinder block has a honing process or an acid or alkali to dissolve the aluminum base metal as a finishing treatment on the inner surface to raise the oil film holding power and the abrasion resistance, thereby raising the Si particles. An etching process is performed. Therefore, when the average particle diameter of the Si particles is less than 1 μm, the wear resistance of the aluminum alloy itself decreases, and in addition, the Si particles easily fall from the surface, and the wear resistance is further improved. Will decrease. Conversely, when the average particle size of the Si particles is 5 μm or more, machinability and extrudability are reduced, and further, the strength of a joint portion of a port hole described later is reduced.

[0013] Cu forms a solid solution in aluminum to increase the strength, and when coexisting with Mg, which will be described in detail later, the tendency is further increased. In the aluminum alloy, 0.3% or more and less than 5.0%, preferably 0. It is preferable to contain it in the range of 3% or more and less than 3.0%. As the addition amount of Cu in the aluminum alloy increases, the strength of the aluminum alloy increases, but the deformation resistance during extrusion molding and the crack limit speed decrease, that is, the extrudability decreases. In particular, in porthole extrusion, extrusion cracks tend to occur at the welded portion, and the corrosion resistance is also reduced.

If the Cu content is less than 0.3%, the strength is insufficient, and if it is 5.0% or more, the extrudability deteriorates.
At a local melting temperature around 50 ° C., the amount of liquid phase increases. Therefore, when a cylinder block is manufactured by casting a cylinder liner, the cylinder liner becomes semi-molten and deforms. If the upper limit content of Cu in the aluminum alloy is less than 3.0%, the local melting temperature rises and the amount of liquid phase when locally melted decreases, so the cylinder liner is cast into the cylinder block. Occasionally, there is almost no risk of deformation.

Mg shows the same tendency as Cu. When the amount of Mg in the aluminum alloy increases, the strength of the aluminum alloy improves, but on the other hand, the extrudability, the joint strength of the port hole, and the thermal conductivity are increased. And the local melting temperature decreases. Therefore, M
g is preferably contained in the aluminum alloy in a range of 0.2% or more and less than 2.0%. If the Mg content is less than 0.2%, the strength becomes insufficient. If the Mg content is 2.0% or more, the effect of increasing the strength is saturated and the above-mentioned extrudability is reduced. In addition, in addition to Si, Cu, and Mg, the molded body of the present invention contains 0.5% or less of Fe, 0.2% or less of Ni, 0.1% or less.
% Or less of Mn, Cr, etc., does not impair its properties.

The cylindrical body is not particularly limited, such as a circle, an ellipse, an ellipse, a polygon, a cone, and a pyramid. The molded body has a shape in which a plurality of these various shapes are juxtaposed. It should be noted that the molded body does not exclude one having a single cylinder, and since the aluminum alloy of the present invention has good extrudability, it is possible to produce a large number of single cylinders in a short time. Yes, it can contribute to productivity improvement.

Next, the production of the aluminum alloy compact having the above-mentioned structure is carried out at 17% to less than 27% of Si (% by weight, the same applies hereinafter), 0.3% to less than 5.0% of Cu, and 0.2% to 2.0% of Mg. %, And the balance consists of Al and unavoidable impurities, and the average particle size of Si particles distributed in the matrix of the composition is 1 μm or more and less than 5 μm. By a porthole method, preferably at 470 ° C. or higher.
This is performed by hot extrusion in a temperature range of 0 ° C. or less to form a plurality of cylindrical bodies in parallel.

First, the predetermined component Al-Si-Cu-
The Mg-based aluminum alloy is rapidly solidified by a spray forming method to obtain a preform (the above aluminum alloy material). In this spray forming method, the above alloy is melted, and the liquidus temperature of the alloy is + 50 ° C. to + 15 ° C.
The preform is obtained by keeping the temperature in the range of 0 ° C., forming fine droplets of the alloy by a gas atomizing method, and depositing and depositing the droplets in a semi-solid state on a collector while cooling rapidly.

At this time, the particle size of the Si particles crystallized by rapid cooling is set to 1 μm or more and less than 5 μm. The gas used in the gas atomization method is an inert gas such as nitrogen or argon, which prevents oxidation of the molten metal and reduces the relative density to 10%.
A preform close to 0% is obtained, and the particle size of the crystallized Si particles is adjusted by adjusting the gas amount.

That is, if the gas amount is too large, it is excessively rapidly cooled and the particle size of the Si particles becomes small, and if it is less than 1 μm, the abrasion resistance becomes insufficient and the deposition yield also decreases. Therefore, the gas amount is 3 kg per 1 kg (M) of molten metal.
８8 Nm ³ (G) (G / M ratio: 3 to 8). When the G / M ratio is close to 3, the particle size of the Si particles is close to 5 μm, and when the G / M ratio is close to 8, the particle size of the Si particles is close to 1 μm. In addition, in order to make the deposited layer uniform, the position of the collector is lowered by an amount corresponding to the amount of the deposited layer while rotating it 2 to 5 times per second to obtain a cylindrical preform.

Next, the obtained preform is cut into an extruded billet, which is preferably manufactured by a porthole method.
Hot extrusion is performed at a temperature of 70 ° C. to 520 ° C. to form a hollow member in which a plurality of cylinders such as cylinder liners are juxtaposed. In addition,
When the hollow profile is a cylinder liner, the cylinder block is manufactured by casting.

The billet for extrusion is manufactured by a powder metallurgy method in addition to the spray forming method. That is, the atomized droplet is solidified as it is to obtain a rapidly solidified powder, and degassing is performed according to a powder metallurgy method. In this degassing process, a can is filled with quenched solidified powder and evacuated at a temperature of, for example, 400 to 500 ° C.,
This is performed by heating the preformed body obtained by cold-pressing the powder to 400 to 500 ° C. in an inert atmosphere or vacuum.
After degassing, the powder is hot-pressed at 300 to 500 ° C. to densify the powder by 100%, and the can filled with the powder is removed.
Obtain an extruded billet. Thereafter, extrusion molding is performed in the same manner as described above to obtain a hollow profile.

[0023]

EXAMPLES Examples of the present invention will be described below, and effects will be demonstrated based on the examples. It should be noted that these examples are for describing a preferred embodiment of the present invention, and the present invention is not limited thereto.

Examples 1 to 10 First, Al— having the composition shown in Examples 1 to 10 in Table 1 was used.
Preforms of a Si-Cu-Mg-based aluminum alloy are manufactured by spray forming (Osprey method) at a G / M ratio of 5, respectively. Each preform has a diameter of 2
70 mm, height 500 mm, which is 254 m in diameter
Each of the extruded billets was cut into a cylindrical shape having a height of 350 mm and a height of 350 mm. Each of the extruded billets extruded the three-piece cylindrical member 1 shown in FIG. 1 through a porthole.

The temperature condition at this time is that the billet is 480
C., the container was 450.degree. C., and the die was 450.degree. C., and the extrusion speed at that time was 0.5 m / min. Each extruded billet is divided into two male entry ports of an extruding die, joined at the position indicated by a horizontal broken line in FIG. 2, extruded from a female opening, and connected to each of the cylinders 3 described above. Shape 1

For each of Examples 1 to 10, (1) extrudability, (2) average Si particle size, (3) bending strength of joint, (4) abrasion loss of disc Abrasion),
(5) Deformation onset temperature due to local melting (to obtain a measure of castability) was measured.

(1) Extrudability: Observed by visual observation. (2) Average Si particle size: Measured by examining the structure of an extruded three-piece cylindrical member by an optical microscope. (3) Flexural strength of joint: Flexural test shown in FIG.
A test piece 3 including the joint 2 in FIG. 3 (dimensions 35 mm × 35 m
mx 4 mm), and the joint 2 is set on the tester 4 so as to be a fulcrum of bending, a load is applied to the pin 5, and the broken load is measured. (4) Abrasion amount of the disk: A disk having a diameter of 40 mm and a thickness of 2.5 mm was sampled from the extruded three-piece cylindrical member.
Measured by pin-disk abrasion test. In this test, the sampled disc and the spheroidal graphite cast iron FCD45
By friction-wearing the mm pin, the surface roughness is traced with a surface roughness meter to measure the wear depth of the disc. The test conditions at this time were that the surface pressure was 1MP.
a, friction speed was 5 m / sec, lubrication was 150 ° C. commercially available engine oil, and friction time was 120 minutes.

(5) Deformation start temperature due to local melting: A test piece having a diameter of 5 mm and a length of 20 mm was sampled from the extruded three-piece cylindrical member, a 10 g compressive load was applied to the test piece, and the temperature was raised. When the length at that time is measured, the test piece initially expands due to thermal expansion, but when local melting starts, expansion stops and contraction starts, and the temperature when contracted by 20 μm is measured and defined as the deformation start temperature.

Comparative Examples 1 to 8 Al-Si-Cu-M of the components shown in Comparative Examples 1 to 8 in Table 2.
Examples 1 to 1 were prepared using g-type aluminum alloy preforms.
It is manufactured under the same conditions as 0, respectively, and further, each cylinder 3 connection shape is obtained under the same conditions. Then, for each of Comparative Examples 1 to 8, in the same manner as in Examples 1 to 10, (1) extrudability,
(2) Average Si grain size, (3) Bending strength of joint, (4) Disk wear (wear resistance), (5) Deformation starting temperature due to local melting (to obtain a measure of cast-in stuffing) , Is measured.

Comparative Example 9 When a preform of an Al—Si—Cu—Mg-based aluminum alloy having the components shown in Comparative Example 9 was produced, the same conditions as in Comparative Examples 1 to 8 were used except that the G / M ratio was set to 2. Along with obtaining a cylindrical three-piece shape, the extrudability and the like were measured in the same manner. Tables 3 and 4 show the above measurement results.

[0031]

[Table 1]

[0032]

[Table 2]

[0033]

[Table 3] << Table Note >> Extrusion possible ○: Extrusion possible Extrusion cracking Cracking A: Minute cracking at the joining position on the inner surface of the cylinder Joint bending strength: Bending strength = M / Z = Wl / H ・ t ^2/6 (W: ^Breaking load , H: specimen width, t: specimen thickness)

[0034]

[Table 4] << Table Note >> Possibility of extrusion ×: Clogging (extruding is impossible even with a maximum load of 2700 tons of the extruder. Extrusion cracking Cracking: Cracking at the joining position on the inner surface of the cylinder

According to Table 3, good products are obtained in Examples 1 to 10, which are excellent in both strength and abrasion resistance (deflecting force is 300 MPa or more, wear amount is less than 0.3 mm). In addition, in Example 5, although fine cracks occurred on the inner surface, it can be determined that there is no problem with the product.

On the other hand, as shown in Table 4, Comparative Example 1 has a small amount of Si and therefore has a large amount of wear. Comparative Example 2 is S
Excessive i content causes poor extrudability and extrusion cracking,
Poor bondability and low bending strength. Comparative Example 3 has a low transverse rupture strength due to small amounts of Cu and Mg, and Comparative Example 4 has a large amount of Cu, resulting in poor extrudability and cracking, and a low deformation start temperature due to local melting.

In Comparative Examples 5 to 7, the deformation resistance was so high that extrusion was not possible. In Comparative Example 8, since 2.5% of Ni was contained, extrudability deteriorated and cracks occurred. In Comparative Example 9, since the G / M ratio was set to 2, the Si particle size was large, the extrudability was poor, cracks occurred, and the bending strength was low.

Examples 11 to 13 The components were 22.5% of Si, 1.0% of Cu, and 0.1% of Mg.
Two aluminum alloy preforms each containing 5%, 0.08% Fe, and the balance of Al and impurities were manufactured by the Osprey method at a G / M ratio of 5. The manufactured preform has a diameter of 270 mm, a height of 1300 mm, and a diameter of 2 mm.
Extrusion billets were formed by cutting out six cylinders having a height of 54 mm and a height of 320 mm, and each of the three extruded billets was porthole extruded in the same manner as in Examples 1 to 10 except that the extrusion temperature was changed. . The same measurement as in Examples 1 to 10 was performed on the obtained three-piece cylindrical connecting member.
The extrusion conditions are shown in Table 5. Table 6 shows the measurement results.

Comparative Examples 10 to 12 Using the same extruded billets as in Examples 11 to 13, except that the extrusion temperature was outside the preferred range of the present invention (470 ° C. or more and 520 ° C. or less), each of the three cylinders was extruded through a porthole. And the same measurement as in Examples 1 to 10 was performed on the obtained cylindrical three-link shape. The extrusion conditions are shown in Table 5, and the measurement results are shown in Table 6.

[0040]

[Table 5]

[0041]

[Table 6]

According to Table 6, in Examples 11 to 13, good products were obtained, and the strength and abrasion resistance (the bending strength was 300 MPa)
As described above, the wear amount is 0.3 mm or less. On the other hand, in Comparative Example 10, since the billet temperature was low, the deformation resistance was high and extrusion was not possible. Comparative Example 11 has a low billet temperature and therefore has a low joint strength, and Comparative Example 12 has a high billet temperature and has a crack on the extruded surface and further has a low joint strength.

[0043]

According to the present invention, Al-Si-Cu-M
The Si content in the g-based aluminum alloy is 17% or more 27
%, The content of Cu and Mg within a predetermined range, and S
i Since the particle size is 1 μm or more and less than 5 μm, it has abrasion resistance while maintaining high strength, and has good deformability and good extrudability, so it is complicated to connect a plurality of cylinder liners. It is possible to extrude even a simple one.

[Brief description of the drawings]

FIG. 1 is a sectional view of an aluminum alloy compact showing an embodiment of the present invention.

FIG. 2 is a perspective view of an aluminum alloy compact showing an embodiment of the present invention.

FIG. 3 is a perspective view of a test piece of an aluminum alloy molded body according to the embodiment of the present invention.

FIG. 4 is a side view of a tester for measuring a transverse rupture force of the aluminum alloy compact according to the embodiment of the present invention.

FIG. 5 is a schematic diagram showing a conventional example.

FIG. 6 is a schematic view of a cylinder liner showing an embodiment of the present invention used for comparison with a conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Cylinder 3 connection shape material 2 Joint 3 Test piece 4 Testing machine 5 Pin a Cylinder liner

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Claims (4)

[Claims] 1. Si 17% or more and less than 27% (weight%, the same applies hereinafter), Cu 0.3% or more and less than 5.0%, Mg 0.2
% Or less and less than 2.0%, the balance being Al and impurities, the average particle size of Si particles distributed in the matrix is 1 μm or more and less than 5 μm. Abrasion resistance characterized by being extruded into a shape in which a plurality of cylinders are juxtaposed,
High strength aluminum alloy compact. 2. Si 17% or more and less than 27%, Cu 0.3
% To less than 5.0%, Mg 0.2% to less than 2.0%, with the balance being Al and impurities, and the Si particles distributed in the matrix having an average particle size of 1 μm to less than 5 μm. A method for producing a wear-resistant, high-strength aluminum alloy molded article, characterized in that said aluminum alloy is hot-extruded by a porthole method into a shape in which a plurality of cylindrical bodies are juxtaposed. . 3. The method for producing a wear-resistant, high-strength aluminum alloy compact according to claim 2, wherein the hot extrusion temperature is 470 to 520 ° C. 4. A cylinder liner for an internal combustion engine comprising the aluminum alloy molded product according to claim 1.