JPH0257658A - High damping material of mg 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 rolling or extruding the ingot of Mg in which Al, Zn and Sn as impurities are regulated to the specific amounts or below and thereafter annealing it under specific conditions. CONSTITUTION:The billet of Mg in which the total amt. of Al, Zn and sn as impurities is regulated to <=0.2wt.% is subjected to homogenizing treatment according to necessary, is thereafter subjected to hot extruding, e.g., at 320 deg.C or hot rolling at 350 deg.C, is worked into a plate material of about 3mm thickness and is successively annealed at 180 to 300 deg.C for <=24hr. The Mg high damping material having recrystallized structure of 10 to 150mum average grain size, having excellent vibration damping characteristics and furthermore having excellent mechanical characteristics such as strength and ductility, excellent formability, dimensional accuracy, surface properties or the like can be manufactured.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention has excellent imaging attenuation and characteristics, and is used as a structural member of sound II equipment, precision equipment, automobiles, etc. that is not suitable for imaging. It is related to the swing material.

[Conventional technology]

Conventionally, Go-N has been used as a so-called vibration damping material for metal materials for structural members of audio equipment, precision equipment, automobiles, etc. that are not suitable for photography.
i-based alloy, Mn-C1, J-based alloy, Ni-"'ji-based alloy, Zn-Aj!-based alloy.

Pure Mg, Mg-Zr alloy, My-N i as well as Fe-0r alloy, Fe-C alloy, Fe-C-3i alloy, etc.
Cast materials such as alloys are known. In particular, Mg-based cast materials have the lowest specific gravity and the highest photographic attenuation among intermediate-grade 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 above-mentioned Mg-based material as a vibration damping material and achieve a level of vibration damping performance, it is necessary to take special care during casting and to cast the cast product under conditions that make it equiaxed rather than columnar. Ta. This is because when the crystal becomes columnar, the photographic attenuation property deteriorates significantly. Furthermore, it is known that when a Mg-based ingot is subjected to plastic working such as rolling or extrusion, the imaging damping properties are significantly deteriorated, although the cause is unknown.

Therefore, the above-mentioned Mg-based materials can only be used in castings manufactured under certain conditions, and rolled materials, extruded materials, and other rolled materials are not used at all because of their inferior photographic attenuation properties. is the actual situation.

[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.

A Mg photographic material made of expanded Mg material that is superior to castings in many respects such as dimensional accuracy and surface properties, and also has the same photographic attenuation properties as castings, and its manufacturing method. It came from a decision method.

That is, the production method of the present invention uses Al as an impurity.

A rolled or extruded Mg material containing less than 0.2% by weight of zn, 3n in total and the remainder being M3, which is characterized by having a recrystallized grain structure with an average grain size of 10 to 150 μm. be.

In addition, the production method of the present invention uses A1゜Zn, 3n as impurities.
Contains less than 0.2% by weight in total, with the balance consisting of Mg
After the ingot is homogenized or rolled or extruded without any treatment, it is annealed at a temperature of 180 to 300°C within 24 hours to obtain a recrystallized grain structure with an average grain size of 10 to 150 μm. It is characterized by this.

(Function) The reason why the amount of impurities contained in Mg is limited as described above in the present invention is as follows.

Aj! , Zn, and Sn normally exist as impurities in the Mg base metal, and their total amount is 0.2% by weight (hereinafter referred to as % by weight).
(abbreviated as ) or above, the dislocation dissociation phenomenon is obstructed, internal friction is reduced, and vibration damping properties are deteriorated.

Mg having such purity 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 is subjected to homogenization treatment as necessary, at the stage where 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 the damping performance, decreases to 1/10 to 1/20 of that of cast material.
It cannot function as a photographic material. However, after finishing rolling or extrusion, the temperature is 180~300'C.
When annealing is carried out for less than 24 hours at a temperature of
As shown in the figure, it becomes a recrystallized grain structure with an average grain size of 10 μm or more, surprisingly recovers vibration damping properties, and exhibits a loss factor 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 to 150 μm or more, if the average grain size is less than 10 μm, the above-mentioned dislocation fixation/desorption phenomenon may occur. This is probably because the chance of interference by grain boundaries increases, or because a very large loss coefficient η cannot be obtained.

Moreover, if the average grain size of the recrystallized grains exceeds 150 μm, the strength decreases significantly.

Also, the reason why annealing was performed at a temperature of 180 to 300'C within 24 hours is because recrystallized grains of 10 μm or more cannot be obtained at temperatures below 180°C, and when the temperature exceeds 300°C or the annealing time exceeds 24 hours, This is because the growth of recrystallization progresses and the recrystallized grains have an average diameter exceeding 150 μm.

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

Example (1) Various types of Mg with the purity shown in Table 1 were melted and cast, and a diameter of 15
0m111. A billet for extrusion with a length of 300 ms was obtained. This was homogenized at 400℃ for 8 hours and then heated to 320℃.
A shape having a thickness of 2IrvrI and a width of 30# was made by hot extrusion. This was annealed at 220° C. for 3 hours to obtain a vibration damping material.

These vibration damping materials are measured using a complex elastic modulus measuring device.
The vibration damping properties were evaluated by determining the loss coefficient η. i.e. thickness 2
Using an InIn test piece with a width of 30 II m and a length of 200 mm, one side was chucked and imaging was forcibly applied using an oscillator, 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 100%
After corroding the grain boundaries with a mixed solution of 5 d of glacial acetic acid and 10 d of distilled water, the average grain size of the recrystallized grains was determined using an optical microscope. These results are shown in Table 2.

As is clear from Tables 1 and 2, the film materials NQ1 to NQ3 of the present invention exhibit excellent imaging damping properties (loss coefficient η), but the comparative damping materials Nα4, Nα5. It can be seen that No. 6 has poor vibration damping properties.

Example (2) Mg having a purity shown in Nα2 in Table 1 was melted and cast to a thickness of 100M and a width of 500M. The ingot was soaked at 420°C for 4 hours, and then hot rolled at 350°C to form a plate with a thickness of 3M. This material was annealed as shown in Table 3 to obtain a vibration damping material, and the photographic damping properties (loss coefficient η), average grain size of recrystallized grains, and mechanical properties 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 restraining materials Nos. 7 to 9 of the present invention have recrystallized grains with an average grain size of 10 to 150 μm, and exhibit good vibration damping properties and excellent tensile strength.

On the other hand, it can be seen that the comparative restraining materials Nα10 to Nα12 are inferior in either the loss coefficient or the tensile strength.

(Effects of the Invention) As described above, according to the present invention, castings have excellent vibration 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 Mg photographic materials made of expanded materials superior to those of conventional methods.

[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 total of 0.2 Al, Zn, and Sn as impurities
1. A Mg vibration damping material, which is a rolled or extruded Mg material containing less than % by weight and the balance being Mg, and having a recrystallized grain structure with an average grain size of 10 to 150 μm. (2) A total of 0.2 Al, Zn, and Sn as impurities
After rolling or extruding a Mg ingot consisting of less than % by weight and the remainder Mg with or without homogenization treatment, 1
A method for producing a Mg vibration damping material, characterized in that it is annealed at a temperature of 80 to 300°C for up to 24 hours to form a recrystallized grain structure with an average grain size of 10 to 150 μm.