JPS5966918A - Double layer structure hollow member made of aluminum alloy - Google Patents

Abstract

PURPOSE:To raise thermal resistance, abrasion resistance and galling resistance by forming a double layer structure consisting of an inner layer made of an Al alloy having a metallic structure which contains Si, Mn, Fe and Ni of a prescribed ratio and is dispersed finely, and an outer layer which is softer than said inner layer. CONSTITUTION:Alloy powder containing 10-30% Si, 3-15% >=1 kind among Mn, Fe and Ni by wt% and the balance Al is prepared. A hollow green compact obtained by hot-compressing this alloy powder is inserted into an Al alloy pipe which is softer than said body, by which a hollow composite billet is formed. Subsequently, a composite structure hollow member 1' is obtained by hot-extruding this billet. As for an inner layer 2 made of an Al alloy having high thermal resistance and abrasion resistance of said member 1', Si crystal particles having <=15mum diameter and an intermetallic compound having 20mum diameter containing >=1 kind among Mn, Fe and Ni are dispersed finely.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to hollow parts made of aluminum or alloys suitable for cylinder liners used in internal combustion engines, swash plate compressors, etc. The present invention relates to a hollow part 14 having a multilayer structure formed by an extrusion method including an inner layer made of an abrasive high-strength aluminum alloy and an outer layer made of an aluminum alloy that is softer than the inner layer.

Recently, car Y? Due to the shift to F=M and the adoption of the front engine/front drive (FF) system, it is necessary to reduce the weight of the engine, and the cylinder block has changed from cast iron to A1 alloy. In order to improve the wear resistance of the WTrtiJ surface of the cylinder block, a cylinder liner made of iron is usually cast into the cylinder block. If this cylinder liner could be made of aluminum alloy, it would not only be lightweight, but also have higher thermal conductivity and coefficient of thermal expansion than cast iron, which would improve the adhesion between the liner and the block even when the temperature rises, and therefore improve engine heat dissipation. is obtained. As a result, the temperature of the liner becomes lower, which prolongs the life of the lubricating oil or allows the use of lubricating oil with a lower viscosity.Also, the coefficient of thermal expansion is similar to that of the aluminum alloy of the piston material, so the distance between the liner and the piston is reduced. Since the clearance can be set small, the consumption of lubricating oil and the generation of blow-by gas can be kept to a small amount, which is expected to improve fuel efficiency and efficiency.

Furthermore, since the high Si content A1 alloy cylinder liner has a small coefficient of friction, it is expected to improve fuel efficiency and output by reducing friction loss between it and the piston ring.

However, conventionally known aluminum alloys are insufficient as cylinder liners for castings as described above. For example, A3 according to the American Aluminum Association standard (AA standard)
90.0 alloy (Si16-18, Cu4-5%, Mg
0.5-0.65%, 1i"e□, 5%, 'lI'i
Casting alloys such as Q, 2%, Zn 0.1%, balance A) (all alloy compositions are expressed in weight percent in this document) require a large feeder because the solid-liquid coexistence temperature range is wide. As a result, the yield is poor, and machinability is poor because primary crystals 8i still crystallize in a large size even with the refinement treatment and die casting method. Furthermore, a fatal flaw is that the cylinder block has fn<”
Since the material is softened by the heat of the molten metal when it is rolled, the wear resistance is significantly reduced, and there are other disadvantages such as chattering and peeling on the machined surface and making honing difficult.

On the other hand, in recent years, the powder metallurgy method has been used to solve the above-mentioned A (
JP 52-109415). According to this, 12~
30%Si, l~5%cu, 0.5~1.5chi4
g. A method of obtaining a hollow body by granulating a molten hypereutectic 1'J-8i alloy with residual A by the Atoine method or atomization method using centrifugal force and extruding it, and the material obtained by this method. Since the primary crystal Si can be made to be 20 μm or less, it has excellent ductility and machinability, a small coefficient of friction, and excellent wear resistance. Furthermore, it has also been proposed to extrude a hollow body by mixing Sin, Sn, graphite, etc. into a powder obtained by adding 0.5 to 1.5 inches of N1 to the A-no-Si alloy having the above composition.

The present inventor conducted a tracing experiment of the above invention, but 2
0chi S+-4 Cu -0,8%Mg -0,5%Ni
- AJ, % remaining standard composition alloy powder extruded material was made into a cylinder liner (outer diameter 73 mm, inner diameter 65 m1n, height 10
5 mm) as ADC12 alloy (JIS H53
According to the results of a die-casting test using a die-casting method at a molten metal temperature of 675°C into a cylinder block (weight: 3.4 kg) of 02), it was found that a cylinder block with a hardness of about l-1nJ3 80 that was treated with T6 before molding was cast. Later, it was found that the HRB had softened to about 40. Therefore, a hollow body of this type of alloy cannot be cast into a cylinder block and used as a cylinder liner.

Castings are made by die-casting or low-pressure casting, but it is preferable to make the liner as thin as possible from a cost perspective, so it is easy to deform due to mechanical stress applied during the liner transportation process and positioning during casting. In order to prevent this, it is necessary to have high rigidity (high hardness).

The inventor of the present invention solved these drawbacks and created a product that does not soften even under the heat load when hooking, does not soften even in the temperature range that is applied during use, and has excellent abrasion resistance and corrosion resistance. As an excellent high-potency aluminum alloy material, the weight ratio is 8.
High 5i-AJ containing 110-30%, alloy with additional 1
M! 1. By adding a large amount of alloying elements such as Fe and Ni, 15
S l grains below μITI and MJI below 20 μm
We have previously presented a heat-resistant, wear-resistant, high-strength aluminum alloy powder compact in which an intermetallic compound containing one or more types (%Fe, Nj ct) is finely dispersed, and a method for producing the same (lI!fjil' No. 1989-119901, Patent Application No. 1199Q2, 1982).

These heat-resistant, wear-resistant, high-strength aluminum alloy powder compacts have the above-mentioned metallographic structure, and are excellent in wear resistance and burnout resistance, as well as heat resistance, even under the action of heat loads. The above-mentioned heat-resistant, wear-resistant, high-strength aluminum alloy powder molded product has very little decrease in hardness and is therefore suitable for use as a cylinder liner material cast into an aluminum alloy cylinder block. is obtained by hot extrusion molding of the powder obtained by rapidly cooling and solidifying the molten alloy, but the alloy powder contains a large amount of intermetallic compounds produced by the addition of Mn, Fe, Ni, etc. When hot extruding a hollow member such as a cylinder liner, the extrusion resistance becomes large, which requires a large capacity extrusion device, requires an extremely low extrusion speed, and shortens the life of the extrusion die. However, there are also problems in that it is difficult to form uneven portions, that is, serrations, on the outer periphery of the cylinder liner to ensure tight connection to the cylinder block.

The purpose of this invention is to provide a hollow part advantage that solves the above problems, and the first invention is to provide a hollow member made of aluminum alloy with an N content ratio of 5i10 to 30%, Mn
, Fe, Ni, 1 type or 2 or more types 3 to 1
5%, the remainder essentially consists of Si crystal grains with a size of 15 μm or less and intermetallic compounds with a size of 20 μm or less containing one or more of the above-mentioned Mn, Fe, and Ni. Aluminum having a scrap structure formed by an extrusion method consisting of an inner layer made of a heat-resistant, wear-resistant, high-strength aluminum alloy having a dispersed metallographic structure and an outer layer made of an aluminum alloy that is softer than the inner layer. , an alloy hollow member and its second invention include Cu□, 5-5T, and
It concerns what MgQ added 2-3%.

The inner layer of the hollow part of the lining structure of the present invention is made of a heat-resistant 11iJ abrasion-resistant high-strength aluminum alloy that does not soften even under the action of heat load and exhibits excellent abrasion resistance and seizure resistance in sliding conditions. , the inner layer J: for soft casting;
Since it has an outer layer of aluminum alloy for die casting or drawing, extrusion processing is easy, and it is possible to iron the hollow body for the purpose of increasing the dimensional accuracy of the hollow body or to form serrations on the outer peripheral surface. It is easy to carry out, and since the outer layer has fewer alloying elements and higher thermal conductivity and coefficient of thermal expansion than the inner layer, it is possible to maintain the temperature of the sliding surface of the inner layer at a lower temperature. At the same time, it has the advantage of more securely adhering to the outer casting hole.

Next, the present invention will be explained by referring to an embodiment of a cylinder liner for a casting shown in the accompanying drawings. The cylinder liner 1 shown in FIG. 1 has a multi-layer structure including an inner layer 2 and an outer layer 3. Inner M2
is Si'10~30%, Mn, Fe, Ni 1
3 to 15 seeds or two or more seeds, and further Cu if necessary
The outer layer 3 is made of JI, which is softer than the inner layer material.
S) (5202 for casting/JISI (5302 for die casting or JISI-14100 for drawing) Made of aluminum alloy or similar alloy.The boundary between the inner layer 2 and outer layer 3 is where the constituent elements are mutually diffused during casting. In the present invention, the chemical composition of the inner layer is as follows.

First, Si is fine Si particles, Mg2Si,
By dispersing it in the matrix as an intermetallic compound such as An -Fe -Si, it exhibits excellent effects on high-temperature strength, wear resistance, and seizure resistance, but if its content is less than 1096, the amount of dispersed crystallization is small. On the other hand, if it exceeds 30%, not only will the melting temperature become high, but even if it is rapidly cooled, primary crystals S+ with a large diameter will precipitate in the powder, significantly reducing the compressibility of the powder. This not only makes it difficult to produce a green compact, but also increases deformation resistance during hot extrusion, lowers the ductility and impact value of the resulting extruded material, or worsens its rigidity. When used as a cylinder liner, the coefficient of thermal expansion decreases as the amount of Si added increases, resulting in poor adhesion with the outer layer I material.
%, but the preferred range is 14 to 25 inches.

Ti"e, Ni, and Mn are added to enhance high-temperature strength by dispersing them as fine compounds by taking advantage of their low solid solubility in phantom and slow diffusion rate in Ap. The total amount of these elements is 3 to 15%, either alone or in combination.When the molten metal is rapidly cooled to form powder, these elements are supersaturated and dissolved in the A-i width, and the amount that cannot be dissolved in the solid solution is A1-Fe-8i ternary compound or AU3N i , Mn sz Si 7 An!5
Intermetallic compounds such as these crystallize as rod-shaped phases in powder and granules. This compound is divided by hot extrusion and finely dispersed in the grain structure, and is further precipitated as the above-mentioned compound from the theoretically saturated portion in the matrix by high temperature heating. These compounds are fine, hard, and
Since the diffusion rate in υ is slow, coarsening is unlikely to occur, so the high temperature strength of the material is increased. It also increases the hardness of the material together with the Si crystal grains in the material, contributing to wear resistance and seizure resistance.

If the amount added is less than 396, the effect is not significant; on the other hand, 15
Exceeding this temperature not only requires high temperatures during melting, but also increases the deformation resistance during compression and extrusion of powder and granules, making extrusion processing difficult. Decreases machinability. Within the above range of 3 to 15%, if Ni is added alone at 5 to 15%, Fe
3 to 15% and one or two of Mn 5 to 15%
When containing seeds, or one or two of Fe 3-12% and M'n 5-12% and Ni 3-1
Particularly good heat resistance and wear resistance properties can be obtained when the content is 0%.

(Although Mg or Mg is added to general Fc5i-kl alloys, it is well known as an element that improves age hardenability.
In the present invention, for this purpose, Cu is added by 0.5 to 5 mm.
You may add 0.2-3% of g. If Cu is less than 0.5% and Mg is less than 0.2%, the above effects will not be sufficiently achieved, and even if Cu is added in excess of 5% and Mg is added in excess of 3%, the above effects will not increase significantly. will no longer be recognized.

Next, an example of a manufacturing method will be described. Molten aluminum alloy adjusted to have a predetermined target chemical composition was atomized by gas atomization to obtain alloy powder having the chemical composition shown in Table 1.

Table 1 (4) All of the structures of the obtained alloy powder particles show a structure in which a large amount of intermetallic compounds grown in a rod shape were crystallized in a matrix in which fine Si crystal grains were dispersed.

FIG. 2 is a micrograph g (740x magnification) illustrating the metal structure of sample material 3.

This alloy powder was sieved and 148 mesh powder was used. It has been found from many experimental results that by doing so, the size of the Si crystal grains in the extruded product can be reduced to 15 μm or less.

Next, 148 mesh powder was preheated to 300°C, put into a splittable mold heated to the same temperature, and compressed with upper and lower punches to form an outer diameter of 175.4 mm and an inner diameter of 66.5 mm.
, a height of 100 mm, and a g density ratio of 70 inches.

A3056TE obtained by hot extrusion method of Nibilet
, A6061TF! (JIS H4080)
Aluminum alloy pipe (outer diameter 294mm, inner diameter 1
75. 5 mm, length 500 mrn), stack 5 of the green compacts and insert them, swage both ends and
It was made into a joint billet.

Next, this middle chamber composite billet was preheated to 450°C in N2 gas, and a container (inner diameter 208°C) kept at approximately the same temperature.
A floating mandrel with a diameter of 6,611 mm is inserted into the hole of the hollow composite fillet, and hot extrusion is performed using an indirect extrusion method to form an inner layer 2 and an outer layer 3 as shown in Figure 1. A multilayer hollow member 1 having an outer diameter of 73 tnm and an inner diameter of 65 mm was obtained.

In the process of hot extrusion, the aluminum alloy powder is compressed and bonded by pressure diffusion accompanied by plastic flow, but the intermetallic compounds existing in the form of rods in the powder are fragmented.
It forms particles in the tissue and is dispersed in faM. Therefore, the inner layer of the obtained multilayer structure hollow member is as shown in FIG.
/! A structure is formed in which primary Sj crystal grains and an intermetallic compound containing one or more of Mn, Fe, and Ni are finely and uniformly dispersed in a base of -Si eutectic.

In the case of the above method, by setting the hot extrusion ratio to 10 or more, the elongated rod-shaped intermetallic compound in the alloy is divided into pieces of 20 μm or less in size and dispersed in the extruded material.

Next, the extruded multilayer structure hollow member was heated at 300°C
After H-r heat treatment, a mandrel with a diameter of 66non is inserted into the hollow part cut to a predetermined length, and a die is placed on the outer periphery, and the serrations are processed at the same time as the ironing process. A hollow body 1' having serrations 4 on the outer surface as shown in FIGS. The boundary between the inner and outer layers of this hollow body is located at a position of approximately 70.5 mm in diameter, and the boundary is metallurgically bonded by diffusion bonding.

The multilayer structure hollow member 1' obtained in this way is ADC
It is die-cast into a 12 alloy cylinder block. The temperature of the molten AIJ012 alloy at this time was 675°C.

The liner of the multi-layer hollow member according to the present invention is cast into an aluminum alloy cylinder block, and the hardness of the inner layer due to the heat load during casting is extremely small, and it still maintains sufficient hardness and can be used for up to 6 months. , exhibits sufficient wear resistance for use in internal combustion engines.

g(r Table 2 shows the inner layer made of the sample powder in Table 1 and the extruded aluminum alloy as described above.
After finishing the cylinder block with a die-casting method and finishing it with an inner diameter of 68 mm, the cylinder block was assembled into an engine, and a durability test was conducted to investigate the quantity.
Power) is expressed as a ratio to the wear debris of a conventional galvanized iron liner. Table 2 also shows the hardness of the inner layer after casting, which is C.

Table 2 Endurance Death I. Rotation speed is 550 Or, p, m. Oil temperature 95℃
, the water temperature was io o 'c, and the mating piston rings used were ones in which the outer circumferential surfaces of the first pressure culling and oil ring were each plated with iron in which SiC was dispersed in an area ratio of 15 to 20% in the iron matrix. did. Note that a cast iron ring without surface treatment was used as the second pressure culling. In addition, in the comparatively old engine that used a cast iron liner, a first pressure culling and an oil ring with chrome plating on the outer circumferential surface were used.

As is clear from Table 2, the cylinder liner made of the multi-layered hollow member of the present invention exhibits wear resistance comparable to that of the conventional flaky aged lead gate iron liner, even if it does not contain Cu or Mg. , Cu, and Mg that are age-hardened have a rather small amount of wear and are sufficiently durable for practical use.

As explained above, the molten aluminum alloy of the chemical composition according to the present invention contains a large amount of 84n, Fe, or Ni, so even if it is atomized by the atomization method or the like and rapidly cooled, Mn that has grown into a rod shape will remain. , Fe
, Nf-containing intermetallic compounds are precipitated in large numbers, and hot extrusion requires a large extrusion device and shortens the life of the extrusion die. However, in the present invention, this alloy powder has a low hardness. Therefore, a composite billet is prepared by holding it in a cylindrical body made of an aluminum alloy for decaying or drawing which has good formability, and it can be easily formed into a hollow body by hot extrusion. In addition, it is easy to perform the necessary machining on the outer periphery of the outer layer, and the outer layer has a lower content of alloying elements and has a higher thermal conductivity and coefficient of thermal expansion than the inner layer, which increases the heat absorption efficiency from the inner layer. It maintains the temperature of the inner wall sliding surface of the inner layer at a low temperature, enables the use of low-viscosity lubricating oil, and provides good tight bonding with the cylinder block body, which is a casting material.

In addition, since the outer layer is made of a soft material, five vertical grooves (serrations) 4 are formed on the outer periphery of the hollow part at the same time as the hot extrusion process of the multilayer structure hollow body or after the hot extrusion process as shown in Figures 4 and 5. It is easy to mold, and can be used as a means for improving adhesion or preventing rotation when used as a cast cylinder litchi in a cylinder block body.

The multi-layer structure hollow FIB of the present invention has an inner layer with S in the base.
i It is made of a heat-resistant, wear-resistant, high-strength aluminum alloy with particularly improved heat resistance by finely dispersing primary crystal particles and intermetallic compound particles, while the outer layer is made of an aluminum alloy for casting or drawing that is softer than the inner layer. Since it is formed by coating the inner layer and extruding it through a die to increase thermal conductivity, it is suitable for applications where a heat load is applied and a high degree of wear resistance and seizure resistance is required.

In addition, in the process of manufacturing hollow parts, graphite, molybdenum disulfide, boron nitride,
The lubricating properties of the inner layer can be further improved by mixing 0.2 to 20 pieces of solid lubricant powder such as calcium fluoride to form the inner layer.

[Brief explanation of the drawing]

Fig. 1 is a cross-sectional view showing an example of the extruded multilayer hollow member material (intermediate process) of the present invention, and Fig. 2 is a photograph showing an example of the microscopic structure of aluminum alloy powder particles used to form the inner layer. (740x), Figure 3 is a photograph (740x) showing an example of the microscopic structure of the inner layer of the extruded hollow part, and Figure 4
Figure 1 is a vertical sectional view showing an embodiment of the present invention, and Figure 5 is a horizontal sectional view. 1... Extruded material (intermediate process), 1'...
Multi-layer structure hollow fτ15, 2... Inner layer, 3...
...Outer layer, 4... Seret lit M11 agents Ibuji Kamoshi 1) Next Male 1st figure 4th figure 5th figure

Claims (1)

[Claims] 1. In the aluminum alloy hollow member, the weight ratio is S
i 10-30%, Mn, Fe, Ni (Q
3 to 15% of one or more of these, the remainder being substantially A
), in which Si crystal grains with a size of 15 μm or less and intermetallic compounds with a size of 20 μm or less containing one or more of the aforementioned He4n, Fe, and Ni are finely dispersed. A hollow made of aluminum alloy having a multilayer structure formed by an extrusion method, consisting of an inner layer made of a heat-resistant, wear-resistant, high-strength aluminum alloy having a Element. 2. The inner layer is made of Ni5 or more among Mn, Fe, and Ni.
Aluminum alloy duplicate structure hollow part according to claim 1, which includes 15 parts. 3. The aluminum alloy hollow member according to claim 1, wherein the inner layer contains 3 to 5 parts of one or both of 3 to 15 parts of Fe and 5 to 15 parts of Mn among Mn, Fe and Ni. 4. The inner layer is Fe among Mn, Fe, and Ni.
3 to 12 chips and Mn 5 to 12 chips or two and Ni
The aluminum alloy hollow part according to claim 1, which contains 3 to 10 pieces on the gold side. 5. In the hollow part made of aluminum alloy, the N area ratio is S
i 10-30%, 3-15% of one or more of Mn, Fe, Ni, CuO, 5-5
H, Mgo, z ~ 3 H, the remainder essentially consists of 8i crystal grains with a size of 15 μm or less, Mn, Fe, N
An inner layer made of a heat-resistant, wear-resistant, high-strength aluminum alloy having a metal structure in which an intermetallic compound having a size of 20 μm or less containing one or more of the following types of i is finely dispersed, and an aluminum alloy softer than the inner layer. An aluminum alloy hollow part characterized by having a multilayer structure formed by an extrusion method with an outer layer of an alloy.