JPH02107738A - Wear-resistant aluminum alloy stock for machining excellent in toughness - Google Patents

Abstract

PURPOSE:To improve the wear resistance, machinability, and toughness of the title aluminum alloy stock by specifying respective contents of Si, Cu, Mg, Mn, Sb, Al, and Fe and also specifying the average grain length of eutectic Si. CONSTITUTION:The title Al alloy stock for machining has a composition consisting of, by weight, 6.5-7.5% Si, 1.5-4.5% Cu, 0.2-0.8% Mg, 0.1-0.8% Mn, 0.05-0.25% Sb, <=0.25% Fe, and the balance Al. Further, the above alloy stock has a structure in which the average grain length of eutectic Si is regulated to 3-5mum and also eutectic Si of <=5mum length comprises 75% (based on the whole eutectie Si). The above Al alloy stock has wear resistance, superior machinability and excellent toughness and can be machined with superior dimensional accuracy.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an aluminum alloy material for processing such as forging, which has wear resistance, good machinability, and excellent toughness.

(Prior art) Hydraulic parts such as vehicles and industrial machinery, sliding parts such as pistons and cylinders, or parts of compressors, etc.
Toughness is required not only for wear resistance but also for safety and to withstand harsh use.

A 4032 alloy CAl-
3i eutectic alloy) have been used. However, A
4032 alloy has low strength and elongation, and is inferior in toughness.

For this purpose, improved alloys such as Cu, Mg, Fe,
Alloys with adjusted elements such as Mn have been proposed (for example, JP-A-60-19'7838).

(Problem to be solved by the invention) Adding Cu to A4032 alloy or Al-5i eutectic alloy
Mg.

T6 treated alloy material with adjusted elements such as Fe, Mn, etc.
Even those with high strength have a strength of about 38-39 kg/mm2 and an elongation of about 8-10%, which is poor in toughness.

Further, although the hypoeutectic Al-5i alloy has improved strength and elongation, and improved toughness, it is still not sufficient.

That is, an object of the present invention is to provide an aluminum alloy material for processing that has wear resistance, good machinability, and excellent toughness.

(Means for Solving the Problems) The inventors have proposed that sb
It has been discovered that an alloy in which the size of eutectic Si and the eutectic Si of a specific size are within a specific range has wear resistance, good machinability, and excellent toughness, and the present invention has been made. This is the completed version.

That is, in the present invention, Si6.5 to 7.5wt%, Cu
1.5-4.5 wt%, Mg0.2-0.8 wt%,
Mn0.1~0.8wt%, Sb0.05~0.25w
t%, the balance consists of Aβ and impurities, Fe as an impurity is less than 0.25wt%, and the average particle length of the eutectic Si is 3 to 5 μm, and the length is 5 μm or less.
It is an aluminum alloy material for machining with excellent toughness and wear resistance, which is characterized by having 75% or more of the total eutectic Si.

(for production) First, the reasons for adding and limiting alloy components will be described.

Si6.5-7.5wt% Si forms eutectic Si and is intended to impart wear resistance, and if its content is below the lower limit, the effect will be small;
If it exceeds the upper limit, the elongation decreases significantly and the toughness is impaired.

Cu1.5-4.5wt% Cu is for imparting strength and elongation after T6 treatment, and if its content is below the lower limit, it will have little effect, and if it is above the upper limit, elongation will decrease and corrosion resistance will decrease. to degrade.

Mg0.2-0.8iyt% FIg is used to generate MgzSi precipitates to impart strength, and if the content is below the lower limit, it will have little effect, and if it is above the upper limit, the elongation will decrease. , deterioration of plastic workability such as forging and extrudability.

Mn0.1-0.8 wt% Mn is Al1-5i-Fe generated by the presence of Fe
If the Aβ-Si-Mn (Fe)-based product is a fine Aβ-Si-Mn (Fe)-based product that improves toughness and provides wear resistance with crystallized substances, and its content is below the lower limit. It has little effect, and if it exceeds the upper limit, the toughness will decrease.

SbO, 05~0.25t% sb is used to refine eutectic Si and impart machinability and toughness.If its content is below the lower limit, it will have little effect, and if it is above the upper limit, it will be less effective. The Mg:+Sb compound crystallizes and reduces toughness, and also reduces the strength-improving effect of Mg.

In particular, the eutectic Si of large diameter billets such as 300 to 600 mmφ is uniformly refined to improve wear resistance and toughness. Moreover, castability is not deteriorated, and small diameter casting rods such as 30 to 100 mmφ can be stably cast.

This is a property that cannot be found in eutectic Si; Na, which has the property of t-refining.

Fe forms fine crystallized substances due to the presence of Mn and improves wear resistance, but when the content increases, Aβ-FeMn-3
Since a large amount of i-series products are generated, which impairs toughness, the blending amount should be adjusted to less than 0.25wt%, preferably 0.1wt%.
less than %.

Excluding Fe (containing impurities such as Zn and Cr reduces toughness, so the content of each is set to 0.05 wt% or less.

Further, it is preferable to add a grain refining agent usually added to prevent casting cracks, for example, Ti in an amount of 0.1 wt% or less, or Ti in an amount of 0.1 imt% or less and B in an amount of 0.02 wt% or less.

Next, let's talk about the organization.

If the average particle length of eutectic Si is 5 μm or more, machinability and toughness will decrease, and if the amount of eutectic Si with a particle length of 5 μm or more exceeds 25% of the total amount of eutectic Si in terms of area ratio. , the elongation and toughness decrease, so the average grain length of eutectic Si is 3
The amount of eutectic Si within the range of ~5 μm and 5 μm or less needs to occupy 75% or more of the total amount of eutectic Si in terms of area ratio.

An alloy material having such a composition and Mi weave is obtained by melting the composition by a conventional method and then forming a cast rod of 30 to 100 mmφ by a water-cooled continuous or semi-continuous casting method using a water-cooled mold. Alternatively, a billet of 100 to 600 mmφ is formed by the above-mentioned casting method, and this is processed at a reduction rate of 50% or more to make an extruded rod of 10 to 130 mm, so that the eutectic Si is fragmented during the extrusion process, and the billet in the above range is An alloy material with a texture can be obtained. This 30-1
If the diameter of a cast rod of 00 mmφ is less than 30 mmφ, the rod will be cooled too rapidly, and the eutectic Si will become even finer, making it impossible to obtain a structure within the above-mentioned range, resulting in a decrease in wear resistance. Further, if the diameter is 100 mm or more, the eutectic Si is large and reduces machinability and toughness. 50
When a billet with a diameter of ~600 mm is extruded to less than ion, the eutectic Si becomes finer due to plastic working, and the structure within the above-mentioned range cannot be obtained, resulting in a decrease in wear resistance. Also 130n
For extruded rods larger than +mφ, the eutectic Si of the billet is large;
Even by plastic working, it is difficult to be refined easily, and a structure within the above-mentioned range cannot be obtained, resulting in decreased machinability and toughness. Billet extrusion processing is not limited to solid bars, but can also be made into hollow materials and shaped materials.

After cutting the alloy material according to the present invention described above into required dimensions,
It is used as a material to be processed into solid products or forged into various parts.

(Example) After melting according to a conventional method, a billet of 325 open diameter was obtained by a water-cooled semi-continuous casting method using a water-cooled mold, and this billet was subjected to homogenization treatment (510 ° C. x 6 hours) and indirect extrusion. The extruded rod was made into a 45 mmφ extruded rod using a machine, and this was used as a sample.

The composition is shown in Table 1.

(The following is a margin.) Micrographs of sample numbers 2 and 4 are shown in FIGS. 1A and B. It can be seen that in sample No. 4 (FIG. 1B) to which sb is added, eutectic Si (black dots) is finely and uniformly distributed.

Micrographs of the cut surfaces of sample numbers 2 and 4 are shown in FIGS. 2A and 2B. It can be seen that sample No. 4 (FIG. 2B), in which sb is added and eutectic Si is finely and uniformly distributed, has small scratches on the cut surface and has good machinability.

Next, the average grain size of eutectic Si and the eutectic Si of 5 μm or less in each sample were measured. These measurements were carried out by an image analysis method, and the average particle diameter of the eutectic Si was taken as the average value of the maximum length of the particles. The results are shown in Table 2.

Next, each sample was subjected to T6 treatment (solution treatment at 510°C for 4 hours - water quenching - tempering treatment at 170°C for 10 hours), and then mechanical properties, notch toughness, and wear resistance were measured. . The notch toughness was measured by performing 50% compression forging in the axial direction of the extruded rod of the sample, making a notch at an angle of 45° perpendicular to the axial direction, and applying a static tensile load. Abrasion resistance was measured using an Okoshi type abrasion tester under the following conditions.

Load 21kg, rotating wear element FC28 Friction speed 1-3 m/sec, friction distance 600m.

The measurement results are shown in Table 2.

(Left below) From the results in Table 2, the alloy material of the present invention has a small average grain size of eutectic Si and has a large amount of eutectic S with a grain size of 5 μm or less, so it has good wear resistance. (It can be seen that the notch toughness is particularly excellent.

On the other hand, it can be seen that the comparative example and the A4032 alloy are inferior in some properties and are not satisfactory alloy materials.

(Effects of the Invention) As described above, the alloy material of the present invention has wear resistance, good machinability, and excellent toughness, so it will not crack even when subjected to highly plastic working such as forging. Hydraulic parts for vehicles, industrial machinery, compressor parts, VTRs, DAs, etc.
It can be used as a material for T cylinders, OA equipment parts, etc., and has the advantage of being able to be processed with high dimensional accuracy and producing highly safe parts.

[Brief explanation of the drawing]

FIG. 1 is a micrograph of eutectic Si, in which A shows a sample without sb added and B shows an example of the present invention with sb added. FIG. 2 is a micrograph of the cut surface, where A shows the one after no sb was added, and B shows the one of the present invention with sb added.

Claims (3)

[Claims] (1) Si6.5-7.5wt%, Cu1.5-4.5
wt%, Mg0.2-0.8wt%, Mn0.1-0.
8wt%, Sb0.05 to 0.25wt%, the balance is Al and impurities, and Fe as an impurity is 0.2wt%.
less than 5 wt%, and the average particle length of eutectic Si is 3 to
A wear-resistant aluminum alloy material for machining with excellent toughness, characterized in that eutectic Si with a length of 5 μm or less occupies 75% or more of the total eutectic Si. (2) The aluminum alloy material for machining with excellent toughness and wear resistance according to claim (1), characterized in that the content of Fe as an impurity is less than 0.1 wt%. (3) Furthermore, Ti0.1wt% or less, or Ti0.1
The wear-resistant aluminum alloy material for machining with excellent toughness according to claim 1 or 2, characterized in that it contains 0.02 wt% or less of B and 0.02 wt% or less of B.