JPH0257657A - High damping material of mg alloy and its manufacture - Google Patents

Abstract

PURPOSE:To manufacture the title material having excellent vibration damping characteristics in which structure is regulated to the recrystallized one of fine grain size by subjecting the ingot of an Mg-Si alloy having specific compsn. to rolling and extruding and thereafter annealing it in the range of specific temp. CONSTITUTION:An Mg alloy contg. 0.2 to 10wt.% Si is refined and cast into a billet. The billet is subjected to homogenizing treatment, e.g., at 470 deg.C for 8hr and is thereafter subjected to hot extruding or hot rolling at 400 deg.C to work into a plate material of 2 to 3mm thickness. The material is annealed at 250 to 500 deg.C for 4hr to 1min to regulate the structure to recrystallized one of >=10mum grain size, by which the Mg alloy high damping material having excellent vibration damping characteristics and having excellent strength, formability, dimensional accuracy, surface properties, etc., is manufactured. Furthermore, in the manufacturing stage, homogenizing treatment to the ingot is not necessarily needed.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention has excellent imaging damping characteristics and is used as a structural member of acoustic equipment, precision equipment, automobiles, etc. that dislikes vibrations.
This article concerns 9-alloy vibration damping materials.

[Conventional technology]

Conventionally, metal materials for structural members of sound equipment, precision instruments, automobiles, etc. that are difficult to photograph have been treated with so-called vibration damping materials (:, o
-Ni alloy, Mn-Cu alloy, N1-Tj alloy,
Zn-A1 alloy.

In addition to Fe-Cr alloys, Fe-C alloys, Fe-C3i alloys, etc., cast materials such as pure Mg, Mg-Zr alloys, and Mg-N + alloys are known. In particular, Mg-based cast materials have the lowest specific gravity and highest vibration damping properties among all practical metal materials, and are being considered for use in housing materials for precision equipment inside missiles, taking advantage of these characteristics.

[Problem to be solved by the invention]

However, in order to use the rV1g alloy mentioned above as a vibration damping material and to exhibit vibration damping properties at the level of a temple, it was necessary to take special care during casting and to cast the cast product under conditions that would make it equiaxed rather than columnar. . This is because the vibration damping properties deteriorate significantly when the crystals become columnar. Furthermore, it is known that when a Mg alloy ingot is subjected to plastic working such as rolling or extrusion, the vibration damping properties are significantly deteriorated, although the cause is unknown. Therefore, the above-mentioned Mg alloy can be used as a damping material only in castings manufactured under certain specific conditions, and rolled materials, extruded materials, and other wrought materials are not used at all because of their inferior vibration damping properties. is necessary in reality.

[Means to solve the problem]

In view of this, the present invention was developed as a result of various studies, and was developed to improve mass productivity, mechanical properties such as strength and ductility, and moldability.

We have developed an Mg alloy vibration damping material made of a wrought Mg alloy material that is superior to castings in many respects, such as dimensional accuracy and surface quality, and also has the same damping properties as castings, and a method for manufacturing the same. It was developed.

That is, the vibration damping material of the present invention contains 0.2 to 10% by weight of 3i,
This is a rolled or extruded Mg alloy material consisting of the remainder MLii and unavoidable impurities, and is characterized by having a recrystallized grain structure with an average grain size of 10 μm or more.

Moreover, the manufacturing method of the present invention is characterized in that MS? After the alloy ingot is homogenized or rolled or extruded without any treatment, it is annealed at a temperature of 250 to 500'C within 24 hours to create a recrystallized grain structure with an average grain size of 10 μm or more. It is characterized by:

(Function) The reason why the composition of the M9 alloy is limited as described above in the present invention is as follows.

3i further enhances the photographic attenuation properties originally possessed by Mg, and improves strength and ductility by making the crystal grains uniform and fine.
If it is less than 10%, the effect will be small, and if it exceeds 10%, the crystal grains will become too fine, resulting in poor vibration damping properties, as well as poor castability (flowability) and malleability. It deteriorates and becomes difficult to manufacture. The preferred addition range of 3i is 0.3i.
It is 4-6%.

In addition, unavoidable impurities include Fe, A1°2n, etc., but if they are in a range of less than 0.1%, they do not particularly impair the effects of the present invention.

The Mg-3i alloy having such a composition is melted and cast according to a conventional method, and the resulting ingot is subjected to a homogenization treatment, or hot rolled or extruded without any treatment. Further, cold rolling is added if necessary.

After the ingot has been homogenized as required, and after rolling or extrusion is completed, the crystal structure becomes a fibrous processed structure extending in the processing direction, as shown in FIG. Under such conditions, the loss coefficient η, which is a measure of vibration damping properties, decreases to 1/10 to 1/20 of that of cast materials.
It cannot perform its function as a vibration damping material. However, after completing rolling or extrusion, when annealing is performed at a temperature of 250 to 500°C within 24 hours, the crystal structure becomes a recrystallized grain structure with an average grain size of 10 μm or more as shown in Figure 2, which is surprising. It recovers the image damping property and shows a loss coefficient η almost equivalent to that of the cast material. This is thought to be the result of annealing, which organizes a large number of entangled dislocations introduced during processing, making it easier for dislocations to stick and detach from impurity atoms, increasing internal friction.

However, even if the recrystallized grain structure has an average grain size of 10 μm or more, the recrystallized grain structure has an average grain size of 10 μm or more.
If it is less than m, this is because there is an increased chance that the above-mentioned dislocation fixation/detachment phenomenon will be hindered by grain boundaries, or because a very large loss coefficient η cannot be obtained.

Furthermore, the reason why annealing was carried out at a temperature of 250 to 500°C within 24 hours is because recrystallized grains of 10 μm or more cannot be obtained at temperatures below 250°C, and excessive oxidation of the surface occurs when the temperature exceeds 500°C, which is inappropriate. It is. Further, the reason why the annealing time is set to within 24 hours is that if the annealing time exceeds 24 hours, oxidation of the surface and grain boundaries will proceed, and this will also result in operational inefficiency.

[Example] The present invention will be explained in more detail below with reference to Examples.

Example (1) Various Mg alloys having the compositions shown in Table 1 were melted and cast to obtain extrusion billets with a diameter of 150 m and a length of 300 mm.

This was homogenized at 470°C for 8 hours and then hot extruded at 400°C to form a shape having a thickness of 2 InM and a width of 30 shoes.

This was annealed at 320° C. for 1 hour to obtain a vibration damping material. The vibration damping properties of these damping materials were evaluated by determining the loss coefficient η using a complex elastic coefficient measuring device. That is, 2 shoes in thickness and 30 shoes in width.

Using a test piece with a length of 200 mm, one side was chucked and an oscillator was used to forcibly image the sample, and the loss coefficient η at the resonance frequency fr was determined using the following equation (1).

A tensile test was also conducted to measure tensile strength and elongation.

In addition, the surface of the shape was coated with 6% picric acid alcohol solution ioo.
After corroding the grain boundaries with a mixed solution of Irdt, 5 mm of glacial acetic acid, and 0 ml of accumulated water, the average grain size of the recrystallized grains was determined using an optical microscope. These results are shown in Table 2.

Table 1 However, Δf has a 3 db value range.As is clear from Tables 1 and 2, the damping material of the present invention N
α1 to α3 have recrystallized grains of 10 μm or more and are excellent in vibration damping properties (loss coefficient η), tensile strength, and elongation.

On the other hand, comparative damping materials Nα4 and S with low 3i content
Although the i content is appropriate, the comparative damping material Nα5 with an average grain size of recrystallized grains smaller than 10 μm has poor imaging damping properties, especially 3
Comparative damping with high i content of 15.9%? It can be seen that JNα6 has poor extrusion processability.

Example (2) An M9 alloy having the composition shown in Nα2 in Table 1 was melted and cast to form an ingot with a thickness of 100 s and a width of 500 m.
After soaking for an hour, it was hot rolled at 390℃ to a thickness of 3.
Finished on a board of m. This material was annealed as shown in Table 3 to obtain a vibration damping material, and the photographic damping property (loss coefficient η) and the average grain size of recrystallized grains were measured in the same manner as in Example (1). These results are also listed in Table 3.

As is clear from Table 3, the vibration damping materials Nα7 to Nα9 of the present invention have recrystallized grains of 10 μm or more and exhibit good vibration damping properties. On the other hand, the comparative damping material Nα10, which has a fiber structure that is not annealed after hot rolling, and the comparative damping material Nα11, which has a low annealing temperature of 220°C, have inferior vibration damping properties and have a high annealing temperature of 530°C. Although the material Nα12 had good vibration damping properties, the surface was severely oxidized, making it unsuitable for practical use.

〔Effect of the invention〕

As described above, according to the present invention, it is possible to produce a molded metal that is superior to cast metals in many respects, such as excellent damping properties, mass productivity, mechanical properties such as strength and ductility, formability, dimensional accuracy, and surface texture. This provides remarkable industrial effects, such as the ability to obtain M9 alloy vibration damping material made of elongated material.

[Brief explanation of the drawing]

Figure 1 is a schematic diagram of processed structure (fibrous structure), Figure 2
The figure is a schematic diagram of the recrystallized structure.

Claims (2)

[Claims] (1) A rolled or extruded Mg alloy material containing 0.2 to 10% by weight of Si, the balance being Mg and unavoidable impurities, characterized by having a recrystallized grain structure with an average grain size of 10 μm or more. Mg alloy vibration damping material. (2) After rolling or extruding a Mg alloy ingot containing 0.2 to 10% by weight of Si and the remainder Mg and unavoidable impurities, a 250 to 50%
A method for manufacturing a Mg alloy vibration damping material, characterized in that it is annealed at a temperature of 0° C. for up to 24 hours to form a recrystallized grain structure with an average grain size of 10 μm or more.