JPH01301832A - Al-sn-pb bearing alloy - Google Patents

Abstract

PURPOSE:To obtain a bearing alloy material having excellent fatigue resistance, seizure resistance and wear resistance in the high temp. range by adding specific amt. of Sr to an Al-Sn-Pb bearing alloy and providing the Si grains deposited in an Al matrix with a graphite shape, elliptic shape or the shape of which the tip has roundness. CONSTITUTION:Sr, 0.01-0.3% by weight, is added to an Al-Sn-Pb bearing alloy contg. 3-35% Sn, 0.1-11% Si, 0.1-10% Pb, 0.1-4% Cu and the balance Al. The shape of the Si grains dispersed and deposited into the Al matrix I of the alloy is formed into a graphite one, elliptic one or the one of which the tip has roundness. The alloy is furthermore subjected to heat treatment, e.g., at 300-350 deg.C to remove its strains and to furthermore increase the sphering of the deposited Si grains. At least a part 3a of Sn-Pb alloy grains 3 adjacent to the Si grains 2 is moreover liquefied by frictional heat to drastically improve the lubricity at the time of using the alloy as a bearing.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to an Al-Sn-Pb bearing alloy, and more specifically, the present invention relates to an Al-Sn-Pb bearing alloy. dispersed, precipitated, and
At has excellent fatigue resistance, seizure resistance, and wear resistance in high-temperature ranges, and is excellent during high-speed and high-load operation.
-Relating to Sn-Pb bearing alloy.

Conventional technology Recently, automobile engines have become smaller, more fuel efficient, and have higher output.As a result, the load on the bearings has increased, the temperature of the lubricating oil has also increased, and the operating conditions for the bearings have changed. It is becoming more and more severe. Most conventional multi-component bearings and Al-based bearings have a surface layer of Pb--Sn based or the like formed on the surface of the bearing base metal by overlay plating or the like. However, bearings with this structure suffer from fatigue and seizure phenomena due to high temperatures on the lubricated surfaces, making them unable to withstand the above-mentioned harsh operating conditions.

Therefore, recently there has been a demand for bearings in which no surface layer is formed by overlay plating or the like.

However, the current situation is that even this type of bearing cannot necessarily exhibit stable performance under the above-mentioned severe usage conditions.

That is, a bearing having an overlay plating layer on its surface has - JIS 115402, Al-1 (10
%Sn, 0.75%Cu, 0.5%N1, AlBa
1l, JIS H5402, Al-2 (6%Sn,
JIS such as 2.5%Cu, 1.0%N1, A/Ba1)
Standard, SAE 780 (6% Sn, 2% Si, 1% Cu
, 0.5%N1.0.1%■1, Aj! Ba1) etc. (
7) As shown in the SAEfi rating, the bearing base metal part is made of a low Sn-A1 alloy with a relatively low Sn content, but the surface of these bearing alloy parts is further coated with pb-sb.
A surface layer is formed by overlay plating of the alloy, and this surface layer constitutes the bearing surface. However, under recent high-load, high-temperature operating conditions, the surface layer of these bearings due to the overlay plating on the surface wears out, leading to seizure, making them unusable. On the other hand, bearings that do not have a surface layer formed on the surface by overlay plating meet SAE 783 (20% Sn, 0.5% S1.1,
0%Cu, 0.1%■1, Aj! As shown in Ba1), the bearing base metal part is high Sn-A1 with a high Sn content.
Made of alloy. However, like this, Sn is 20%
To some extent, the alloys contained have low hardness, making the Al matrix weak and unable to withstand high loads.

In addition, regardless of the Sn content, bearing base metals made by adding PB to Al-Sn alloys to improve lubricity and provide seizure resistance are available, for example, by Mizuno I. It is described on page 139 of "Bearing Base Metal" published by Kogyo Shimbun, and this bearing base metal contains 10% Sn, 1.5% Cu, 0.5% S.
Al-Sn containing i and adding 3% pb
- It is a Pb-based alloy.

Furthermore, since pb in Al-Sn-Pb alloys hardly forms a solid solution with Al, in order to improve the dispersibility of this Pb, Al-Sn-Pb-Sb alloys with added sb were developed. No. 52-12131, and furthermore, A
Al-Sn added with cr to strengthen the X matrix
-Pb -Sb -Cr alloy
It is described in No. 85. However, these Al-S
N-PB alloys were developed for the purpose of improving lubricity during normal operation, and have the drawback of not exhibiting sufficient fatigue resistance under high-load operating conditions. The reason for this is that the mechanism for lubrication between the shaft and bearing under high load operation is fundamentally different from that under normal viscous operation.

From this point on, a basic study was conducted on the differences between the lubrication mechanism under high load operation and that under normal operation, and one of the results of this study was that coarse S
A bearing in which l is dispersed and precipitated has been proposed in Japanese Patent Application Laid-Open No. 58-64336.

This bearing has a cutting force due to the hard S1 precipitate, and because it has the cutting force, the surface unevenness of the mating shaft is scraped and flattened, improving the bearing performance.

To explain in more detail, on the surface of the mating shaft made of graphite cast iron on which spherical or flaky graphite has been precipitated, recesses remain after the graphite particles that fell off during polishing, and around these recesses there is hard work-hardened paris. Convex portions such as edges and edges are generated. Therefore, the above At-Sn system, Al-Sn
- In a bearing base metal made of Pb or the like, abnormal wear is likely to occur during high-load operation due to these uneven portions. On the other hand, in the bearing base metal in which the coarse Si is dispersed and precipitated, the cutting force is applied by the hard Si precipitates, so the uneven parts of the mating shaft are mechanically cut and flattened. , therefore,
No abnormal wear or seizure occurs.

However, when the mating shaft is made of a material other than graphite cast iron, during high-load operation, the surface of the mating shaft is scratched irregularly by coarse Si precipitates, causing seizure and causing major problems.

Problems to be Solved by the Invention The present invention aims to solve the above-mentioned drawbacks, and specifically,
In At-Sn-Pb bearing alloys, the content of SnflIPb, etc. is increased to improve lubrication, and Cr, Sb%Mn is added to strengthen the At matrix.

Elements such as N1 are added to increase the hardness of the Al matrix, but on the contrary, these measures actually make the A1 alloy brittle, and during high-load operation, it is difficult to use at high temperatures (100 to 250°C). This means that it does not exhibit fatigue resistance. In this invention, Al
This problem is solved by precipitating Si particles in the matrix, which are elliptical, spherical, or have a rounded tip.
In this way, seizure resistance and wear resistance are improved.

Means for solving the problem and its function are as follows: The bearing base metal according to the present invention has a die-to-mold ratio of 3 to 3.
5% Sn, 0.1-11% S1, Hini 0.1-10
In an At-Sn bearing alloy that contains 0.1 to 4% Cu in addition to 0.1 to 4% Pb, the remainder is substantially Al,
The W feature is defined as the dispersion and precipitation of spherical, elliptical, or rounded-tip Si particles in an Al matrix containing 0.0 to 0.3% Sr.

A more detailed explanation of the configuration of these means and their operation will be as follows.

First, the present invention has been accomplished in order to improve fatigue resistance under high temperature conditions.

That is, in the conventional example, c is simply a high melting point element.
R, co, N*, etc. are added to increase high-temperature strength, prevent hardness from rapidly decreasing at high temperatures, and improve wear resistance. However, in this way, Al-Sn
- In order to increase the fatigue resistance of Pb-based alloys at high temperatures, it cannot be achieved by adding high-melting-point elements to the skewers to increase their strength. and the impact value decreases.

Regarding this point, in the present invention, in order to provide a bearing base metal suitable for severe conditions under high temperature and high load, Sr is added as an essential component, and this Sr is made to act on 81 at the time of casting to form a silicon crystal. Spheroidization of particles or Sit! A part of the i-crystal grains is spheroidized, that is, the tips of the Si crystal grains are rounded, and the spheroidization or rounding of the S1 crystal grains is increased by heat treatment under normal conditions, thereby making Al -
Sn-pb gold alloy enhances tensile strength, elongation and impact strength.

In other words, - Fatigue resistance within a membrane is determined by the tensile strength, elongation, impact strength, and structural structure of the material, and cannot be solved simply by adding bearing components. However, in the present invention, 81 crystal grains are made spheroidal during casting by sr, and this spheroidization is further enhanced by sr during heat treatment.

In addition, in the present invention, since deterioration of mechanical properties can be prevented by the addition of Sr, even if high melting point elements are added to the Al-Sn-Pb alloy as mentioned above as additive elements, the deterioration of mechanical properties can be prevented at high temperatures. No sudden deterioration of mechanical properties. Such characteristics of the present invention can be supported by the fact that an improvement in fatigue strength was observed as a result of conducting a fatigue test under high temperature and high load.

Next, by precipitating spherical or rounded 31 particles in the matrix as described above, a bearing surface that is suitable for high temperature and high load conditions and has significantly improved surface performance can be obtained. .

- It is said that it is difficult to unambiguously understand the phenomenon of seizure within the film because the process that leads to it is complex and is achieved through the synergistic action of multiple conditions.
Bearings made of Cu-Pb alloys have a surface layer formed by overlay plating of -8n alloy. Under high load operation, the surface layer of this plating becomes hard! This results in burn-in. On the other hand, s
Consisting of an Al-Sn-Pb alloy containing l, Cu,
Seizing does not occur in bearings that do not have a surface layer formed by overlay plating on the surface.

The inventors of the present invention took note of this and conducted a comparative structural inspection of both bearings. That is, FIG. 3 is an enlarged sectional view of the - section of a bearing having a surface layer formed by overlay plating (hereinafter simply referred to as overlay plating) on the surface,
FIG. 4 is an enlarged cross-sectional view of a part of the bearing which is made of a l-Sn-Pb base metal and has no overlay plating layer on the surface (and also contains Sl, CU, etc.). Like (
, this bearing consists of a surface overlay plating II 4, an alloy layer 5 and a back metal 6, and the entire surface of this overlay plating 4 supports the shaft rtI weight. On the other hand, as shown in FIG. 4, a bearing made of an Al-Sn-Pb alloy containing Si, Cu, etc. consists of an alloy layer 5 and a backing metal 6, and the matrix of this alloy layer 5 has a rod-like or piece-like shape. 81 of
Particle 2 is precipitated.

Therefore, in this bearing, the load of the mating shaft is supported by the hard Si particles 2, and moreover, the Si particles are waiting for the cutting force as described above.

In short, the difference between the two is surface contact and point contact, and this difference makes a decisive difference in lubrication and temperature rise of the friction surface. In other words, in surface contact, as in the bearing shown in Figure 3, the temperature of the friction surface rises rapidly under high speed and high load conditions, whereas in point contact, as in the bearing shown in Figure 4, the temperature of the friction surface increases rapidly under high speed and high load conditions. A gap is formed between the surface of layer 5 and the surface of the mating shaft, and since a very large load is not applied to the oil film in this gap, sufficient yJ debris is retained and temperature rise on the friction surface is suppressed.

Proceeding further, the present inventors took the basic viewpoint that supporting the shaft load by point contact as shown in Fig. 4 is extremely effective for rA slippage under high loads, and made the most of its effect. Through research on the composition and structure of the bearing base metal according to the present invention, they were able to complete the bearing base metal according to the present invention.

Specifically, the present inventors A I -Sn -1'
We focused on the precipitation form of Sl in the bearing base metal, which is a b-based alloy and contains Si, CU, etc., and conducted research on the effect of this form on the lubricating surface. First, we found that the m point of Sl is It is a highly stable substance and has strong non-metallic properties, and has a temperature of 200°C to 5°C compared to Fe, the main component of the mating shaft.
It has been found that Si is extremely suitable as a point support means for the axial load because it does not cause any diffusion or dissolution even when it comes into contact at a high temperature of about 00°C.

Second, when supporting a mating material at a point via an oil film, Si particles are so hard that their Vickers hardness reaches 599, and since they are not compounds, they are not brittle, have high elasticity, and exhibit rapid changes in vJ. It was found that it could withstand the load.

However, although Si has the above properties, it has strong crystallinity, and even in the form of eutectic precipitation with At,
It has a plate-like or rod-like shape, and its shape changes only slightly even after subsequent rolling and heat treatment. For this reason,
If the precipitation form of Si particles is not controlled from the time of casting, as shown in FIG.
The 81 particles 2 precipitated together with the i-Pb alloy particles become root-shaped or rod-shaped, while the S
Roll b alloy particles 3 will be present. In this state, the mating shaft is likely to be scraped and scratched by the edges of the hard Si particles 2, and on the contrary, the lubricity is reduced and seizure occurs.

From this point of view, in the present invention, in order to dramatically improve the lubricity, the cutting force is removed from the 81 particles, and the edges are controlled to have a rounded shape, such as spheroidization.

That is, FIG. 1 is an enlarged cross-sectional view of a part of a bearing base metal according to one embodiment of the present invention, and as shown in FIG.
The i-particles 2 are spherical, and the spherical 81-particles 2 bring the contact closer to the ideal point contact, making it possible to further improve lubricity and wear resistance. Furthermore, even if a high load is suddenly applied at high speed, the mating shaft will not be damaged. Also, Sl
Since the particles are spherical, there is no notch effect in the matrix, and a matrix with stable strength and wear resistance can be obtained.

This spheroidization of Si particles can be achieved by improving the properties of the A1 alloy liquid phase at the eutectic point where 31 precipitates by adding Sr, and furthermore, even if the conditions are normal in the subsequent heat treatment, Spheronization is enhanced by Sr.

Furthermore, the addition of sr changes the precipitation form of the Sn-Pb agglomerated particles 3, and as shown in FIG.
The Sn--Pb alloy 3 is present more adjacent to the surface. This structure dramatically improves the lubrication performance compared to the conventional structure (see, for example, FIG. 5).

In addition to solving the surface performance structurally as described above,
At is highly sensitive to heat <, when the temperature exceeds 150℃,
Since it softens to below 1 Ivlo and loses its strength, it is necessary to strengthen the matrix at high temperatures, and from this point Cu is added.

In other words, ELL is solid-dissolved with Al to temporarily harden the All matrix. When Cu is in the range of 0.1 to 4%, a portion of the Cu is dissolved in solid solution and the remainder is precipitated, and the balance improves the strength with which the Al matrix is strengthened.

As described above, in the present invention, instead of simply adding a base strengthening element as in the conventional case, Sr is added together with the reinforcing element CU to improve not only the hardness but also the tensile strength and elongation compared to the conventional method. The purpose is to increase fatigue resistance and improve bearing performance under high load operation.The structure and composition of each component are explained as follows.

In the bearing configured as shown in Fig. 1, the lubricating surface that supports the shaft load is the tip of the 31 particles 2 protruding from the surface of the matrix 1, and an oil film is interposed between the 81 particles and the mating shaft, and the lubricating surface that supports the shaft load is Maintains lubrication. However, this oil film ruptures when subjected to rapidly fluctuating loads, reaching local boundary lubrication.
At this time, if a Sn-Pb alloy film is interposed on the upper surface of the 81 grain 2, it is possible to prevent seizure and to ensure normal
The a-film is regenerated and the state of fluid lubrication can be quickly restored. In this case, too, in the structure shown in FIG. 1, Sn-pb alloy particles 3 exist near the 81 particles 2, and this alloy has affinity ff with the lubricated surface even in the molten state.
Therefore, it is difficult to run out of oil. Also, the mating shaft and Si
With FJ [with particles, even if the Si particles become high temperature, 5i-
Heat is absorbed by the heat of fusion of Pb, and A/
Seizing occurs between the alloy and the mating shaft.Also, at this time, as shown in Figure 2, the Sn
At least a portion of the -Pb alloy particles 3 are in a liquid phase, and this liquid phase 3 is supplied to the protruding surfaces of the Si particles 2.

This supply amount increases as the temperature increases, and since the Sn--Pb liquid phase 3a is always present on the lubricated surface of the 31 particles 2, overheating can be prevented. in short,
31 particles 2 are spheroidized, and Sn-1)b alloy particles 3 are added to this.
The structure in which the two are adjacent to each other is very effective in the boundary lubrication state (the oil film has broken), and even in the normal fluid lubrication state, the hard Si particles 2 are properly adapted to the mating shaft, and the soft Sn-1lb garden is very effective. This acts as a shock absorber.

The reasons for limiting each element as described above are as follows.

First of all, among the elements that form a strong Al matrix, the range of CU is set at 0.1 to 4% because if the addition exceeds 4%, the number of inter-precipitates increases, and it becomes brittle. be.

Further, an appropriate lubricating surface can be formed with Sn in the range of 3 to 35% and Pb in the range of 0.1 to 10%. In addition, Si has seizure resistance,
It is effective in improving wear resistance, and adding up to 0.1 to 11% can sufficiently maintain this lubricating structure.

In addition, Sr controls the shape of Si to be spherical, and furthermore, Sr+
-Pb particles are precipitated near the S1 particles, and it is an extremely effective element. However, if the amount of S is less than 0.01%, there will be no such addition effect, and if it is more than 0.3%, cavities are likely to occur during casting, which may even cause problems.

Example Next, examples of the present invention will be described.

Example 1 First, an Al-Sn bearing alloy having the composition shown in Fig. 1 was cast as a plate material with a thickness of 20 m by continuous casting, and the upper and lower surfaces of each cast billet were milled by i, om, and then cooled. It was rolled down to a thickness of 2III11 by inter-rolling.

In this state, heat treatment was performed at 300 to 350° C. to remove strain, and during this time, the bearing was crimped to a steel backing plate via a thin plate of pure A/ to obtain a bearing having a thickness of 1.501111 mm.

Among these bearings, test materials NL1-5 are conventional test materials that do not contain S, and Ni6-10 are related to the present invention. No. 10 is one to which Cu is added.

Each of these test materials was used as a bearing at normal temperature and
To examine the mechanical properties at 00°C, tensile strength, elongation and hardness tests were carried out and are shown in Table 2. In addition, the backing metal of each sample material was removed by machining and AX-8
N alloy part only, K scale shape is JIS z 22
01 No. 5.

From these results, the test materials Nt 6 to 10 show less strength loss at high temperatures (200°C) than conventional materials, indicating the effect of Cu addition. It is thought that the strength and elongation were improved due to the puncture.The elongation was also improved compared to the conventional example, and it can be said that the overall mechanical properties at high temperatures were improved.

Next, in order to find out the 114 seizing property and wear resistance of the sample materials, a test was conducted using the Suzuki type Mahara wear test M1, and the test conditions were as follows.

Massage speed 4/sec Mating material 345G, hardness H, C=55 roughness 0.8~1, O3 Oil used SAE, 201-40 Oil temperature 150±5℃ Seizure load 1 100kg/CI2 to 10kq/[) '
The blood pressure is increased every 15 minutes until burn-in occurs in 5 steps, and the blood pressure at which burn-in occurs is defined as the burn-in vJ weight.

11i4 abrasion resistance On the other hand, to check the abrasion resistance, 100k
Test at a constant g7/[1l12 for 6 hours and observe changes in heavy equipment after that.

The results are shown in Table 2.

According to this, all of sample materials No. 6 to 10 showed better seizure resistance and wear resistance than conventional materials, and the surface performance was also improved by adding Sr and matrix-strengthening elements. Recognize. This indicates that the alloy according to the present invention has an excellent lubrication mechanism.

Next, we actually processed each sample material into a bearing shape and @
When we conducted an internal bearing fatigue test, we found that
The results shown in the table were obtained. This test was conducted under the following conditions, with the bearing fixed to the connecting rod and an eccentric load applied to the shaft, almost the same as in an actual engine, and the performance was maintained without seizure or damage. This is a test that evaluates the length of time.

Surface pressure 600kgr/cy' rotation
Number 400Or, l), DI mating material FC
Lower 0, roughness 0.8-1.5S oil used SAE
201-40 Oil temperature 150℃±5℃ The upper limit of this test time is 300 hours, N=5
The average values are shown in Table 2. As a result, the platinum of the present invention has a longer durability time than the conventional materials of comparative examples, and the platinum of the present invention has excellent fatigue resistance. (The changes in the Si morphology in sample material k81 were examined by deep etching using each sample so that the shape of 31 grains could be seen, and examined using an electron microscope. It was found that Si was spheroidized by the addition of .

Example 2 In order to confirm whether the bearing base metal according to the present invention has the effect of improving the brittleness of the alloy by adding a high melting point metal etc. as a reinforcing agent of the At matrix, impact value was measured as a substitute property. was measured, and the improvement effect of the addition of Sr was determined through experiments.

A comparative experiment was conducted using H.5, which is a conventional material not containing Sr, shown in Table 1 of Example 1, and sample material &8, which is a material according to the present invention, as test materials.

The experiment was conducted using a No. 3 test piece (1n=5) prepared using the Charpy impact test method using Moon S z 2242.

As a result of the experiment, the conventional material had an average of [10,84 kg -ml', but the material according to the present invention had an average of [3,00 kg -ml']
l/CI2, and obviously the bearing base metal according to the present invention is S
An improvement effect due to the addition of r was observed.

<Effects of the Invention> As explained in detail above, the present invention has an effect of 3 to 3% by weight.
59', Sn, 0.1-11% S1 and 0.1-1
0% Pl), 0.01-0.3% sr and C
ub, 1 to 4%, the remainder substantially consists of Al, and 81 particles are precipitated in this matrix in the shape of a sphere, an ellipse, or a shape with a rounded tip. It is.

The bearing alloy of the present invention with this configuration has extremely excellent lubricity,
In addition, the bearing base metal has extremely good mechanical properties at high temperatures of 100 to 250°C, and can sufficiently withstand the harsh conditions of use due to high-load operation.

[Brief explanation of the drawing]

FIG. 1 is an enlarged sectional view of a part of a bearing base metal according to an embodiment of the present invention, and FIG.
An explanatory diagram of the mechanism, FIGS. 3 and 4 are enlarged sectional views of a part of a conventional bearing, and FIG. 5 is an enlarged sectional view of a part of the bearing base metal of FIG. 4. Code 1...Matrix 2...31
Particle 3...Sn-1'l+alloy particle 3a...
...Sn-Pb liquid phase 4 ...Overlay plating 5 ...Bearing alloy lI6 ... Back metal patent applicant KoNDC Co., Ltd. Agent Patent attorney Yoshi Matsushita Katsu Attorney Fumihiro Soejima Figure 1 Figure 2 Eaves with 3Sn-Pb

Claims (1)

[Claims] 1) Contains 3-35% Sn, 0.1-11% Si and 0.1-10% Pb, as well as 0.1-4% C
In an Al-Sn bearing alloy containing U and the remainder being substantially Al, 0.01 to 0.3% of Sr is added to form a spherical, elliptical or rounded tip in the Al matrix. An Al-Sn-Pb-based bearing alloy characterized by dispersing and precipitating Si particles having a shape of .