JPH036344A - Aluminum alloy having heat resistance and wear resistance - Google Patents

Abstract

PURPOSE:To obtain a heat- and wear-resisting Al alloy excellent in strength at high temp. and impact strength by dispersing specific amounts of hard grains into an Al alloy matrix which contains specific amounts of Si, Fe, Cu, and Mg and in which Si, etc., are finely dispersed. CONSTITUTION:The heat- and wear-resisting Al alloy applicable to various sliding members can be obtained by dispersing 1-8%, by weight, of hard grains of one or more kinds among SiC, Si3N4, Al2O3, TiN, TiC, etc., having 1-20mum average grain size into an A2 alloy matrix which has a composition consisting of 4-9% Si, 3-10% Fe, 1-6% Cu, 0.3-3% Mg, and the balance Al with inevitable impurities and further containing, if necessary, 0.3-3%, in total, of one or more elements among Mn, Mo, V, Zr, Ni, Ti, and Cr and in which Si grains and intermetallic compound grains are finely dispersed into a state of <=10mum.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a heat-resistant and wear-resistant aluminum alloy that can be applied to various sliding members such as valve spring retainers and pistons, rocker arms, compressor vanes, and valve lifters. be.

[Prior Art] Recently, engines have been manufactured using aluminum alloy instead of conventional steel H to reduce weight and save energy. However, since various sliding parts such as valve spring retainer pistons, rocker arms, valve lifters, and compressor vanes require high-temperature strength, wear resistance, and impact properties, aluminum alloys that satisfy these properties are difficult to find. It's hard to get caught. Therefore,
Steel was often used, but recently 5i-Ni-
A high-strength aluminum alloy in which hard particles are dispersed in an Al-based, 5iFe, or Mn-A I-based alloy matrix has been proposed. (For example, see Japanese Patent Publication No. Sho 63-20297 and Japanese Patent Publication No. Sho B3-20298.) [Problems to be Solved by the Invention] Particularly in an engine, when the engine rotates at high speeds (for example, close to 10,000 revolutions or more), the movement of the valve system The followability of the valve may deteriorate, and furthermore, a phenomenon known as valve surging may occur, where the valve is unable to close completely due to the force of the spring.

In order to prevent this phenomenon, it is necessary to reduce the weight of the valve system by using an aluminum alloy. This includes reducing the weight of valve spring retainers and valve lifters.

The present invention aims to provide an aluminum alloy for use in valve spring retainers and other members that are subject to severe impact vibrations and sliding.

[Means for Solving the Problems] The present invention provides Sl: 4 to 9%, Fe: 3 to %, Cu:
1-6%, Mg: 0.3-3% or further Mns Mo, V, Zr.

Contains a total of 0.3 to 3% of one or more of Ni, Ti5Cr, and the remainder is A1 containing unavoidable impurities, and the average particle size of Si particles and intermetallic compound particles is fine to 10 μI or less. Si having an average particle size of 1 to 20 μm is dispersed in the aluminum alloy matrix.
C.

It is a heat-resistant and wear-resistant aluminum alloy in which 1 to 8% of one or more types of hard particles such as Si3N4, Al2O3, and TiN are dispersed.

The reasons for limiting the alloy components and hard particles in the above are as follows.

St: Al due to coexistence with Si particles and Fe
-Dispersed as a 5i-Fe intermetallic compound to increase tensile strength. If it is less than 4%, the strength will be insufficient, and if it exceeds 9%, the effect on strength will be saturated and the impact strength will decrease.

Fe: By coexisting with an Al-Fe based intermetallic compound and Si, it is dispersed as an Al-5i-Fe based metal foil compound and increases strength. If it is less than 3%, the strength is insufficient, and 10%
If the value exceeds 100%, the impact strength decreases.

Cu: Coexists with Mg and imparts age hardening properties.

Age hardening improves tensile strength and fatigue strength. If it is less than 1%, the effect will not be sufficient, and if it exceeds 6%, the effect will be saturated and the corrosion resistance and impact strength will decrease.

Mg: Coexists with Cu and imparts age hardenability.

Age hardening improves tensile strength and fatigue strength. 0,3
If it is less than 3%, the effect is insufficient, and if it exceeds 3%, the effect is saturated.

MnSMo, V, Zr, Ni, Ti, Cr: Forms an intermetallic compound with Al or A1 and other additive elements to increase tensile strength. If it is less than 0.3%, the effect is not sufficient;
%, the impact strength decreases.

Hard particles: SiC, 5L3N4, Al2O3, TiN5
Wear resistance is greatly improved by adding hard particles such as TiC. If the average particle size is less than 1 μm, sufficient wear resistance cannot be obtained. Further, it becomes difficult to uniformly disperse the particles, and if the particles are unevenly distributed, the impact strength and fatigue strength will be insufficient. When the average particle size exceeds 20 μm, machinability deteriorates. If the amount added is less than 1%, wear resistance will not be sufficient. Also 8
%, the impact strength decreases.

An example of manufacturing the alloy of the present invention is as follows. Aluminum alloy powder and hard particles are mixed at a predetermined mixing ratio, and this is subjected to cold compression, degassing, hot extrusion, and heat treatment. Each item will be explained in detail below.

100% aluminum alloy powder, such as atomization method, single roll method, spray roll method, etc.
A quenched body in which intermetallic compounds and Si particles are finely dispersed is prepared by a method that allows a cooling rate of ℃/sec or higher. The faster the cooling rate is, the finer the intermetallic compounds and Si particles become, and the tensile strength and fatigue strength are improved.

Further, it is desirable that the Al powder particle size be fine in order to uniformly disperse the hard particles.

Mixing: A process for uniformly mixing hard particles with A1 alloy powder. (1) Mixing is performed using an agitating mixer such as a blender or a pulverizer such as a ball mill.

Cold compaction: The powder is densified to 65-80% of its true density in order to facilitate handling of the powder and to allow a large amount of powder to be charged when charging the powder into capsules. This can also be omitted.

Degassing: Removes moisture adsorbed on the powder surface, especially the Al alloy powder surface, to prevent blisters and pores that occur during final heat treatment. Degassing is performed by evacuation while heating and maintaining the temperature at 300°C to 520°C. If the temperature is lower than 300°C, moisture removal is not sufficient, and heat treatment causes blisters and pores, reducing tensile strength and fatigue strength.

When the temperature exceeds 520°C, intermetallic compounds and Si particles become coarse, and strength, fatigue strength, and impact strength decrease.

Hot extrusion: Performed to densify the powder to 100% density. In order to firmly bond the powders together, it is desirable to have an extrusion ratio of 4 or more.

Heat treatment: Necessary to increase tensile strength and fatigue strength. It is performed by solution treatment → quenching, or solution treatment - quenching = tempering.

[Example] After manufacturing various A1 alloy powders by air atomization method 1
The particles were classified to 49 μm or less, and mixed with hard particles in the proportions shown in Table 1 using a rotary mixer. This powder was compressed with a cold mold to form a compressed product of φG3X 150 nun (
relative density of about 70%) and charged into an aluminum can.
Vacuum degassing treatment was performed at 80° C. for 1 hour. The aluminum can was then sealed and used as a billet for extrusion. Thereafter, the billet was heated to 400 °C, a rod with a diameter of 18++ un was obtained by indirect extrusion (container diameter 70III11) (extrusion ratio 15), and solution treatment was performed at 480 °C for 1 hour.
Water quenching and aging treatment at 175°C for 5 hours were performed.

The thus obtained material was measured for tensile strength at L 50 'C, fatigue life and Charpy impact value at room temperature, and was also subjected to a pin-disc wear test. The results are also listed in Table 1.

Here, the amount of wear refers to the wear test (120'C mashinura with the pin as gold and the disk as Fe12, 10
This is the reduction in the length of the pin when friction is performed for 1 hour at a surface pressure of 0 kgf'/ant and a speed of 0.5 ml/sec.

Fatigue life is determined by notch shape factor α in rotating bending fatigue tests.
It is expressed as the number of repetitions until breakage when a stress amplitude of 7 kgr/mn+2 is applied to a test piece of =3.1. The Charpy impact test piece was made of a smooth material.

As is clear from Table 1 above, the alloy No. of the present invention.

1 to 11 have good tensile strength, fatigue strength, impact strength, and resistance♀
It shows wear and tear. Tensile strength is 30kg1'/mm' or more, fatigue life is 106 or more, Charpy impact value is 1
．． A value of 3 kgf-m/cm' or more was considered good.

Alloy No. 12 has an excessive amount of Si, so its Charpy impact value is poor. Alloy No. 13 has poor tensile strength and fatigue strength due to low Fe content. Alloy No. 14 has an excessive Fe content, so its Charpy impact value is poor.

Alloy No. 15 does not contain hard particles and therefore has poor wear resistance. Alloy No. 1G has small hard particles and therefore has poor wear resistance. Furthermore, since the hard particles were not uniformly dispersed, the fatigue strength was also poor. Alloy No. 17 has a lot of hard particles, so its Charpy impact value is poor. Furthermore, since the hard particles were not uniformly dispersed, the fatigue strength was also poor. Alloy No. +8 does not contain CuSMg and therefore has poor fatigue strength. Alloy No. 19 has an excessive amount of Si, so its Charpy impact value is poor. Alloy No. 2
0 has poor fatigue strength because it does not contain Si. Alloys 1 No. and 21 have large hard particles and have poor machinability, making them impractical.

[Effects of the Invention] According to the present invention, an aluminum alloy having excellent high-temperature strength, impact strength, and wear resistance can be obtained. Therefore, the alloy of the present invention is a material that can replace conventional steel products such as valve spring retainers, valve lifters, rocker arms, and pistons.

Claims (2)

[Claims] (1) Si: 4-9% (weight%: same below) Fe: 3-9%
10%, Cu: 1-6%, Mg: 0.3-3%,
SiC, Si_3N_4 with an average particle size of 1 to 20 μm is contained in an aluminum alloy matrix in which the remainder is Al containing unavoidable impurities and in which Si particles and intermetallic compound particles are finely dispersed with an average particle size of 10 μm or less. ,
A heat-resistant and wear-resistant aluminum alloy comprising 1 to 8% of one or more hard particles such as Al_2O_3, TiN, and TiC dispersed therein. (2) Si: 4-9%, Fe: 3-10%, Cu: 1-
6%, Mg: 0.3-3% and further Mn, Mo, V, Z
Contains a total of 0.3 to 3% of one or more of r, Ni, Ti, and Cr, and the remainder consists of Al containing inevitable impurities, and the average particle size of Si particles and intermetallic compound particles. SiC, Si_3N_4, Al_2O_3, TiN, T with an average particle size of 1 to 20 μm are contained in an aluminum alloy matrix in which particles are finely dispersed to a size of 10 μm or less.
A heat-resistant and wear-resistant aluminum alloy containing 1 to 8% of one or more types of hard particles such as iC dispersed therein.