JPH0240727B2 - - Google Patents

Description

[Detailed description of the invention]

"Industrial Application Field" The present invention relates to an aluminum bearing alloy, and more particularly to an aluminum bearing alloy that has improved strength at high temperatures, improved seizure resistance, and increased fatigue strength. "Conventional technology" Conventionally, aluminum bearing alloys have been
Efforts were made to improve strength at high temperatures, improve seizure resistance, or increase fatigue strength, and the
Publication No. 14866, Special Publication No. 14866, Special Publication No. 14866, Special Publication No. 14866, Special Publication No. 14866
Publication No. 21447 is known. The aluminum bearing alloy disclosed in Japanese Patent Publication No. 52-12131 contains 3 to 40% Sn, 0.1 to 5% Pb, and 0.1 Sb by weight.
- Less than 3% Cu, 0.2-2% Cu, and the balance Al, and if necessary, any one of Ni, Mn, and Si should be added in an amount of 0.2-3%. The main points are as follows. The aluminum bearing alloy disclosed in Japanese Patent Publication No. 58-14866 contains 3.5 to 35% Sn, 0.1 to 1% Cr, and Si1 by weight.
~10%, Mn, Sb, Ti, Ni, Fe, Zr, Mo, Co,
1 to 10% of one or more of the following, the total amount of which is 10%
The following and the balance consist of Al, and if necessary, Cu and/or Mg is 3.0% or less, or instead of this, or together with this, Pb, Bi, In
The gist is that one or more of these are added in an amount of 9% or less. The bearing alloy of Japanese Patent Publication No. 52-21447 is 3.5~
4.5% tin, 3.5-4.5% silicon, 0.7-1.7% copper and up to 0.5% iron, up to 0.2% titanium, 0.2%
The gist is a bearing alloy consisting of aluminum containing the following usual impurities: manganese, less than 0.2% magnesium and less than 0.05% each of boron, cadmium, zinc, lead, etc. "Problems to be Solved by the Invention" Each of the above-mentioned known aluminum bearing alloys has superior performance compared to conventional ones, but as with recent internal combustion engines, there is a demand for smaller size and higher output. As this trend advances, bearing materials are used under higher load and higher temperature conditions, and under these adverse conditions, conventional bearing materials can suffer from fatigue failure, abnormal wear, seizure, etc. This was a contributing factor. "Means for Solving the Problems" In order to solve these problems, the present inventors aimed to improve strength at higher temperatures, improve seizure resistance,
In order to increase fatigue strength, we have found more effective combinations of the various elements mentioned above. The composition of the aluminum bearing alloy, which is a feature of the present invention, will be explained. The aluminum bearing alloy according to the present invention has an Al content of more than 20% Sn3 and less than 20%, and more than 0.2% Mn and 1.2% by weight.
% or less, Cu0.2-2%, Si1.5-8%, V, Nb,
The total amount of at least one of Mo and Co with Mn is
More than 0.2% and less than 1.2% added. Sn in the aluminum bearing alloy of the present invention is an element added mainly for the purpose of lubrication.
If it is less than 20%, there will be no lubrication effect, and if it exceeds 20%, the whole will become soft and the load bearing capacity and fatigue resistance will decrease. The amount of Mn added exceeds 0.2% and is added up to 1.2%.
If it is less than 0.2%, no significant improvement in high temperature strength can be expected, and if it exceeds 1.2%, too much precipitate will precipitate, making the bearing alloy too hard. A more preferred range is 0.3-1.0%, and the most preferred range is
It is 0.4-0.8%. The maintenance of high-temperature strength, microstructural effects, etc. due to the addition of Mn will be described later. The amount of Cu added is 0.2% to 2%, and this is added to further reduce the decrease in strength at high temperatures. If it is less than 0.2%, the effect cannot be expected to be that great, and if it is added in excess of 2%, it becomes too hard, inhibiting rolling properties, and also reduces corrosion resistance. A more preferred range is 0.2-1.5%, and the most preferred range is 0.5-1.2%. Si is added for the purpose of improving wear resistance, and the amount added is 1.5 to 8%. If it is less than 1.5%, the amount of precipitation will be small and no effective improvement in wear resistance will be observed.On the other hand, if it is added in excess of 8%, too much precipitate will precipitate, resulting in poor rolling properties and making it difficult to repeat rolling and annealing. This is because the miniaturization of Sn is hindered. A more preferable range is 1.5% to 5%,
The most preferred range is 2-4%. At least one or more of V, Nb, Mo, and Co,
The total amount with Mn exceeds 0.2% and is added up to 1.2%. That is, the amount of these components added is from a trace amount to less than 1%. The purpose of these additions is to increase the recrystallization temperature of the Al base and to prevent these intermetallic compounds from moving the Al grain boundaries. If the total amount with Mn exceeds 1.2%, coarse precipitates will form, which will adversely affect strength, elongation, and fatigue, which is undesirable. "Effect" In order to confirm the effects of various combinations of each element as described above, various experiments were conducted on the aluminum bearing alloys shown in Table 1.

【table】 The test results are shown in Table 2.

[Tensile strength test]

Testing machine: Instron type tensile testing machine Tensile speed: 5 mm/min Test piece: JIS No. 6 [Sienck fatigue test] Testing machine: Sienck type flat plate bending tester Measuring fatigue strength 10 ^{to 7} times at 3000 cycles/min Atmosphere temperature: 175 ±5℃ [Reciprocating load fatigue] Testing machine: Soda type dynamic load tester Rotation speed: 2100-3100rpm Shaft diameter: Diameter 40mm Shaft: S50C quenched (Hv500-600) Lubricating oil: SAE 10W-30 Oil amount: 140± 5°C Load: 40 Kg/cm ² Measurement of fatigue strength 10 ⁷ times Furthermore, the aluminum bearing alloys shown in Table 3 were tested for fatigue contact pressure and seizure contact pressure.

【table】 The test results are shown in Table 4.

[Seizing surface pressure test]

Test machine: Journal type seizure tester Rotation speed: 1000 rpm Shaft diameter: Diameter 52 mm Shaft: FCD70 (Hv230-250) S50C quenching (Hv500-600) Lubricating oil: SAE 10W-30 Oil amount: 140 ± 5℃ Load: 30 minutes From Tables ² and 4, the aluminum bearing alloy of the present invention is more effective than the comparative aluminum bearing alloy in terms of tensile strength, fatigue strength, and fatigue at high temperatures. I understand. The reason for this will be explained in detail below. Mn, V, Nb, Mo, and Co increase the recrystallization temperature of Al by solid solution in Al, and the solid solution itself increases the hardness of the Al base, but at the same time, several times Even by rolling, the hardness increases compared to when casting. Increasing the recrystallization temperature is effective in maintaining stable mechanical properties even in the high-temperature range that internal combustion engine bearings are exposed to. Improves bearing strength in high temperature areas. Also, Al-Mn, Al-V, and Al- precipitate beyond the solid solubility limit.
Intermetallic compounds such as Nb, Al-Mo, and Al-Co exist stably even at high temperatures, and the fine dispersion of these precipitates increases the recrystallization temperature and helps maintain high-temperature hardness. Doing so will have a positive effect. Furthermore, if the above precipitates exist finely dispersed in the Al base metal, the intermetallic compounds cannot be directly
Preventing the movement of Al grain boundaries, that is, the coarsening of Sn particles,
This leads to keeping the Sn particles, which have been refined through repeated rolling and annealing, as they are.
It has the various effects mentioned above. In addition, the fact that Sn particles remain fine and exist in the Al base metal also means that Sn particles, which have a low melting point of 232°C,
It is also effective for preventing the elution phenomenon of particles at high temperatures. This kind of effect also exists to some extent in Cr, but in the case of Cr, Sn begins to coarsen after 30 minutes at 450°C.
In the case of Mn, V, Nb, Mo, and Co, they have the ability to prevent Sn from becoming coarse even at 500°C for 30 minutes, and as shown in the experimental results later, Mn has a better effect than Cr. It turned out that. It has been revealed that addition of Sb produces coarse precipitates of AlSb, which adversely affects strength, elongation, and fatigue, and that Sb has no effect on improving tensile strength and fatigue strength. In addition, the effect of Cu on strength is due to Mn and V,
It is produced when one or more of Nb, Mo, and Co are added at the same time, and Cu alone cannot be expected to have the effect of increasing strength at high temperatures. In other words, when Cu is added to Al, the hardness increases significantly during rolling, and even at the same rolling rate, the increase in hardness is remarkable compared to Al materials with other elements added, but up to nearly 200℃ It easily softens when heated and cannot maintain high temperature strength.
On the other hand, when Mn and one or more of V, Nb, Mo, and Co are added together with Cu, the hardness increased during rolling due to the addition of Cu increases even after annealing.
It does not decrease much due to the effects of adding V, Nb, Mo, and Co. Therefore, an aluminum bearing alloy with high strength can be obtained, and its strength does not deteriorate as much as in conventional alloys of this type even at high temperatures. Si itself has high hardness and excellent castability, and its precipitates are extremely hard, reaching approximately 1000 on the Bitkers hardness scale, so they significantly reduce bearing wear due to sliding with the shaft. be able to. For bearings that are softer than the shaft, the bearing surface will be cut, and as this situation progresses, the bearing surface will become rougher, the clearance between the shaft and the bearing will increase, and no oil film will form, causing damage to the shaft and bearing. Direct contact, that is, metal contact, often occurs, leading to seizure, but since the above precipitates are harder than hardened steel shafts as well as cast iron shafts, it improves wear resistance when using cast iron shafts. It is particularly effective in improving seizure resistance. In this way, Si originally improves the seizure resistance and wear resistance of bearings, especially the seizure resistance of cast iron shafts. In addition, when Si, Mn, and one or more of V, Nb, Mo, and Co are added at the same time, the shape of Si tends to become relatively round due to subsequent repeated rolling and annealing.
The crystallization diameter also tends to become slightly larger, which further increases the aforementioned effect of improving seizure resistance and wear resistance. "Example" The aluminum bearing alloy of the present invention will be described below. Samples 1 to 10 in Table 5 are inventive materials, samples 11 to 14
shows each component of the comparative material and the results of various tests.

【table】

[Rotating load fatigue test]

Testing machine: Rotating load tester Rotation speed: 8000rpm Surface pressure: 300Kg/cm ² shaft diameter: Diameter 40mm Shaft: S50C quenching (Hv500~600) Lubricating oil: SAE 10W−30 Oil amount: 120~160℃ 10 ⁷ times Measurement of the critical temperature of the back surface of the bearing that can withstand the test From the test results in Table 5, it can be seen that the aluminum bearing alloy of the present invention is superior to the comparative aluminum bearing alloy. In particular, with regard to tensile strength, there is no significant difference between the comparative materials when the oil temperature is 20°C, but when the oil temperature is 175°C.
A clear difference appears. Therefore, Mn,
It can be seen that the addition of V, Nb, Mo, Co, and Cu sufficiently maintains the strength at high temperatures. In addition, in the seizure test using the S50C shaft, FCD70
A noticeable difference was found in the seizure test using a shaft. Furthermore, even more remarkable differences were found in fatigue tests using a Sienck flat plate bending tester, a Soda dynamic load tester, and a rotating load tester. Note that samples for which test results are not listed in Table 5 have not been tested. "Effects of the Invention" As described above, according to the present invention, it is possible to achieve the effects of further improving high-temperature strength, improving seizure resistance, and increasing fatigue strength compared to conventional materials.

Claims (1)

[Claims] 1 Weight% over Sn3 and up to 20%, Mn over 0.2% and up to 1.2%, Cu0.2-2%, Si1.5-8%, V,
An aluminum bearing alloy consisting of at least one of Nb, Mo, and Co, together with Mn, in a total amount of more than 0.2% and less than 1.2%, and the balance substantially consisting of Al.