JP6760584B2 - Extruded member of magnesium alloy - Google Patents

Description

The present invention relates to an extruded member of a magnesium alloy obtained by extruding a magnesium alloy containing magnesium as a main component.

Various metal materials are used to form housings and structural materials in various devices such as electric appliances, transportation devices such as automobiles and aircraft, precision devices, and manufacturing machines. The housings of such various devices are not only made of a single metal material such as iron or aluminum, but also various alloy materials are often used.

For example, in electrical products and transportation equipment, alloy materials may be used for the purpose of weight reduction. In precision equipment and manufacturing machines, alloy materials may be used for the purpose of improving durability and strength. As described above, various alloy materials have come to be used also in the equipment in which the conventional single metal material is used and the constituent parts of the equipment. In particular, in the field of electrical products, usability is required, and in the field of transportation equipment, low fuel consumption is required. Therefore, alloy materials that are lightweight yet have excellent durability and strength are available in various types of these devices. It is designed to be used for parts.

In particular, weight reduction of transportation equipment is required for the purpose of low fuel consumption and low pollution. Transport equipment is equipped with many metal parts, and it is the basis of weight reduction of transport equipment that each of these many various parts is made of lightweight metal or alloy.

Under these circumstances, magnesium, which has the lowest density, is attracting attention as a metal that can be used as a material. The density of magnesium at room temperature is 1.7 g / cm ^3, which is about 1/4 the density of iron and about 2/3 the density of aluminum. It is also known that magnesium is excellent in properties such as specific strength, specific rigidity, machinability, dent resistance, and vibration absorption.

Due to these characteristics, magnesium has been used in small electronic devices such as the housings of notebook computers and mobile terminals. As a further development, as described above, it is desired to be used for various parts of transportation equipment which is a large product.

In particular, in various transportation devices such as vehicles, trains, ships, and aircraft, weight reduction is a necessary condition in order to realize high fuel efficiency and operability. We are working to reduce the weight by reducing the number of parts and reviewing the structure of structural materials, but there are limits to these measures. In order to realize the required weight reduction, it is necessary to reduce the weight of the metal material itself used for parts and structural materials. Among these, magnesium metal has been attracting attention as a metal material as described above.

However, magnesium is easily ignited at a low temperature and has a problem of low strength characteristics (low flame retardancy) in a high temperature environment. When magnesium metal is applied to equipment that easily generates heat, such as transportation equipment, the problem due to its low flame retardancy becomes apparent.

For example, many transportation equipment is often driven by an engine mechanism. Various parts used in transportation equipment are susceptible to heat from the engine mechanism and heat from driving, and are likely to be in a high temperature environment. Unlike small electronic devices, it was difficult to apply magnesium metal to each part of the transportation device due to this heat resistance problem.

In order to cope with such flame retardancy of magnesium metal, a magnesium alloy in which calcium is added to magnesium has been proposed (see, for example, Patent Document 1).

Japanese Unexamined Patent Publication No. 2000-109963

Patent Document 1 describes that a flame-retardant magnesium alloy containing 0.1 to 15% by weight of calcium is plastically processed, or in addition to the existing content of the flame-retardant magnesium alloy containing 0.1 to 15% by weight of calcium. Discloses a magnesium alloy for producing a high-strength flame-retardant magnesium alloy by further adding aluminum or zinc at the time of melting and plastically processing after cooling.

In order to improve the flame retardancy of a magnesium alloy, Patent Document 1 aims to contain calcium in magnesium. According to Patent Document 1, in a magnesium alloy containing calcium in magnesium, the ignition temperature rises and the flame retardancy increases.

However, although the magnesium alloy of Patent Document 1 has improved flame retardancy, it has a problem of insufficient strength.

In the magnesium alloy of Patent Document 1, calcium and aluminum are added to magnesium. By this addition, an intermetallic compound (crystallization phase, representative composition: Al ₂ Ca) containing Al and Ca as main components is formed in the produced magnesium alloy. This intermetallic compound is large in size and brittle. For this reason, when a strong load is applied to the magnesium alloy, there is a problem that fracture occurs starting from this intermetallic compound. As a result, the magnesium alloy of Patent Document 1 has a problem of insufficient strength.

In addition, the fact that the application of a strong load causes fracture starting from the intermetallic compound is highly likely to cause fracture during plastic working such as extrusion or rolling. Therefore, there is a problem that the ductility required for plastic working is also insufficient.

That is, the magnesium alloy of Patent Document 1 has a problem that it is insufficient in both strength and ductility and does not have a sufficient balance between strength and ductility.

As described above, in recent years, magnesium alloys have been required to be used as a metal material in order to reduce the weight of transportation equipment. Even if the problem of flame retardancy can be solved, there is a problem that it cannot be used for structural members such as vehicle frames and bodies due to insufficient strength and ductility (workability). Structural members such as ship frames and aircraft main structures also have problems that cannot be used.

Further, there is a problem that it is difficult to apply to structural members that require a complicated shape due to insufficient workability due to insufficient ductility. In order to use it in various parts of equipment, it is necessary to perform various plastic working such as extrusion and rolling, but this is because the required plastic working cannot be performed due to insufficient ductility.

As described above, the magnesium alloy of the prior art has a problem that it is difficult to apply it to structural members such as transportation equipment due to insufficient strength and ductility.

An object of the present invention is to provide a plastic working member made of a magnesium alloy, which can realize flame retardancy while achieving strength and ductility in a well-balanced manner.

In view of the above problems, the extruded member of the magnesium alloy of the present invention contains 8.0% by mass to 11.0% by mass of Al with respect to the whole.
With respect to the whole, 0.0 mass% to 3.0 mass% Zn and
With respect to the whole, 0.5% by mass to 2.5% by mass of Ca,
Mn of 0.0% by mass to 0.6% by mass with respect to the whole,
Consists of the rest of magnesium and unavoidable impurities
The average value of the Vickers hardness of the intermetallic compound composed of the Al ₂ Ca phase is 350 to 600.

The plastic working member of the magnesium alloy of the present invention can realize high strength and ductility while realizing flame retardancy. This strength and ductility are at a level that can be replaced with aluminum alloys used for structural members of transportation equipment and the like.

In addition, it has a good balance of strength and ductility, and has merits that are not limited to either one.

Combined with these, the plastically processed member of the magnesium alloy of the present invention can be applied to parts such as structural members that require durability against a high load in various devices such as transportation devices. As a result, the weight of the device can be reduced.

It is a flowchart which shows the manufacturing process of the magnesium alloy plastic working member in Embodiment 2 of this invention. It is a schematic diagram which shows the melting process which melts a material in Embodiment 2 of this invention. It is a schematic diagram explaining the solution treatment in Embodiment 2 of this invention. It is a schematic diagram which shows the extrusion process in Embodiment 2 of this invention. It is a table which shows the experimental result about the difference in the temperature of the solution treatment in Embodiment 4 of this invention. It is an SEM photograph (cross-sectional structure photograph) of an Example and a comparative example in Embodiment 4 of this invention. The photograph when the Vickers hardness of the intermetallic compound (crystallized product, representative composition: Al ₂ Ca phase) was measured is shown.

The plastically worked member of the magnesium alloy according to the first invention of the present invention contains 8.0% by mass to 11.0% by mass of Al with respect to the whole.
With respect to the whole, 0.0 mass% to 3.0 mass% Zn and
With respect to the whole, 0.5% by mass to 2.5% by mass of Ca,
Mn of 0.0% by mass to 0.6% by mass with respect to the whole,
Consists of the rest of magnesium and an unavoidable mixture
The average value of the Vickers hardness of the intermetallic compound containing Al and Ca as main components is 350 to 600.

With this configuration, a plastic working member of magnesium alloy with a good balance of strength and ductility can be realized.

In the plastic working member of a magnesium alloy according to the second invention of the present invention, in addition to the first invention, an intermetallic compound containing Mg and Al as main components (representative composition: Mg ₁₇ Al ₁₂ phase) is a magnesium matrix. It is precipitated inside.

With this configuration, the strength of the plastic working member of the magnesium alloy can be increased.

In the magnesium alloy plastic-processed member according to the third invention of the present invention, in addition to the first or second invention, the particle size in the cross-sectional structure photograph of the magnesium alloy plastic-processed member taken by a scanning electron microscope. The area ratio of the intermetallic compound having a value of 1 μm or less is 2% or more.

With this configuration, the area ratio of the fine intermetallic compound (precipitation phase) is high, and the strength can be increased without deteriorating the ductility of the plastically processed member of the magnesium alloy.

In the magnesium alloy plastic working member according to the fourth invention of the present invention, in addition to any one of the first to third inventions, the average particle size of the magnesium matrix recrystallized particles of the magnesium alloy plastic working member is 5 μm. Is less than.

With this configuration, the particle size of the magnesium matrix is small, so that the strength and ductility of the plastic working member of the magnesium alloy are increased.

In addition to any one of the first to fourth inventions, the plastically worked member of a magnesium alloy according to the fifth aspect of the present invention has a tensile strength of 340 MPa or more and a breaking elongation of 8% or more in a room temperature tensile test.

With this configuration, it is possible to use a plastically processed member of a magnesium alloy even in a field where an aluminum alloy has been conventionally used. As a result, it is possible to reduce the weight of various parts and structural members.

In the plastic working member of the magnesium alloy according to the sixth invention of the present invention, in addition to any one of the first to fifth inventions, the magnesium alloy before the plastic working was subjected to a solution treatment by heating at a predetermined temperature.

With this configuration, the hardness of the intermetallic compound (crystallized phase, mainly Al ₂ Ca) of the plastic working member of the magnesium alloy can be controlled to a required level.

In the magnesium alloy plastic working member according to the seventh aspect of the present invention, in addition to the sixth invention, the predetermined temperature is 450 ° C. to 525 ° C.

With this configuration, the hardness of the intermetallic compound (crystallized phase, mainly Al ₂ Ca) of the plastic working member of the magnesium alloy can be controlled to the required level.

The magnesium alloy plastic working member according to the eighth invention of the present invention is a magnesium alloy plastic working member produced through predetermined plastic working in addition to any one of the first to fifth inventions. The plastic working is one of extruding, rolling, forging and drawing.

With this configuration, it is possible to realize a plastic working member of magnesium alloy having a good balance between strength and ductility.

In the magnesium alloy plastic working member according to the ninth aspect of the present invention, in addition to the eighth invention, the magnesium alloy before extrusion processing and the extrusion processing die are heated to 250 ° C. to 300 ° C. Extruding is performed.

With this configuration, the particle size and area ratio of the intermetallic compound (precipitation phase, representative composition: Mg ₁₇ Al ₁₂ phase) can be controlled to a target level, and the crystal particle size can be controlled.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(Inventor's analysis)
As described in the prior art, a magnesium alloy in which calcium or aluminum is mixed with magnesium can exhibit flame retardancy. For example, AMX602 and AZX612, which are flame-retardant magnesium alloys containing aluminum and calcium as additive elements, have flame-retardant properties.

However, these magnesium alloys having such flame retardancy have insufficient strength, and the processed members obtained by plastic working the magnesium alloy also have insufficient strength. Due to the lack of strength, it is difficult to apply it to fields where strength and durability are required, such as parts and structural materials of various devices.

The inventor analyzed the cause of the insufficient strength of the flame-retardant magnesium alloy of the prior art and its plastically worked member as follows.

The magnesium alloy obtained by adding an element to magnesium contains an intermetallic compound (crystallization phase or precipitation phase) formed by the reaction of each element. This intermetallic compound tightly bonds the parent phase of magnesium, which is the main component.

However, the flame-retardant magnesium alloy of the prior art has a problem that the hardness (Vickers hardness) of the intermetallic compound (mainly the crystallization phase, the representative composition: Al ₂ Ca phase) formed during solidification is too low. If the hardness of the intermetallic compound is too low or too high, it becomes brittle and the magnesium alloy is destroyed starting from this intermetallic compound. That is, the intermetallic compound whose hardness is too low or too high serves as a fracture starting point, and the strength of the magnesium alloy is weak.

That is, it was analyzed that the weakness of the flame-retardant magnesium alloy is due to the hardness of the intermetallic compound (mainly the crystallization phase) being too low or too high.

Furthermore, the inventor has analyzed that the hardness of the intermetallic compound (mainly the crystallization phase) is too low or too high due to the following reasons.

(1) Composition component of highly flame-retardant magnesium alloy (2) Particle size of intermetallic compound. In particular, the number of intermetallic compounds with a small particle size is small in the whole. (3) Particle size of the parent phase

Based on these analyses, the inventor adjusted the hardness of intermetallic compounds (mainly crystallization phase, representative composition: Al ₂ Ca phase) and used them for equipment parts and structural members while maintaining flame retardancy. A magnesium alloy composition-processed member having a possible level of strength has been realized.

(Embodiment 1)

(Overview)
The plastic working member of the magnesium alloy in the first embodiment is
With respect to the whole, 8.0% by mass to 11.0% by mass of Al and
With respect to the whole, 0.0 mass% to 3.0 mass% Zn and
With respect to the whole, 0.5% by mass to 2.5% by mass of Ca,
Mn of 0.0% by mass to 0.6% by mass with respect to the whole,
Consists of the rest of magnesium and an unavoidable mixture
The average value of the Vickers hardness of an intermetallic compound (typical composition: Al ₂ Ca) containing Al and Ca as main components is 350 to 600.

Here, the plastic working member is a working member obtained by subjecting some kind of plastic working to an ingot or the like obtained by melting or stirring a necessary material.

As described above, the plastically processed members of the magnesium alloy consist of 8.0% by mass to 11.0% by mass of Al and 0.0% by mass to 3.0% by mass of Zn with respect to the whole. From 0.5% by mass to 2.5% by mass of Ca, 0.0% by mass to 0.6% by mass of Mn, and the balance of magnesium and an unavoidable mixture. Become. Magnesium as a main component contains aluminum (Al), zinc (Zn), calcium (Ca), and manganese (Mn). The unavoidable mixture is a component that is unavoidably mixed in the manufacturing process of the magnesium alloy or the plastically processed member of the magnesium alloy.

The magnesium alloy plastic working member of the first embodiment (hereinafter, abbreviated as “magnesium alloy plastic working member 1”) contains calcium and thus has flame retardancy. In addition to this, by containing aluminum and manganese in the above-mentioned component ratios, the strength is also improved.

The magnesium alloy plastic working member 1 having components having these component ratios contains an intermetallic compound (crystallization phase) containing aluminum and calcium as main components. As an example, a crystallized phase of Al ₂ Ca is generated and contained. This intermetallic compound of Al ₂ Ca has a Vickers hardness of 350 to 600 (average value). When the Vickers hardness of the intermetallic compound of Al ₂ Ca is 350 to 600 (average value), the hardness is neither too low nor too high.

The intermetallic compound (crystallization phase, representative composition: Al ₂ Ca phase) is distributed inside the magnesium matrix, which is the main component of the plastic working member of the magnesium alloy, and bonds the matrix. If the hardness of the intermetallic compound (crystallization phase) is too low, the overall strength is weakened, and the strength of the magnesium alloy is lowered.

The magnesium alloy plastically processed member 1 has a Vickers hardness of 350 to 600 (average value) of the intermetallic compound (crystallization phase) of Al ₂ Ca, so that the hardness is too low to reduce the strength or the hardness is high. It is possible to prevent it from becoming too brittle. As a result, the problem analyzed as being caused by the weakness and brittleness of the intermetallic compound can be solved, and the magnesium alloy plastic working member 1 can realize high strength in addition to flame retardancy.

By achieving both flame retardancy and high strength, the magnesium alloy plastic working member 1 can be applied to parts and structural members in various devices such as electronic devices and transportation devices.

Further, as an intermetallic compound (precipitate), an intermetallic compound containing magnesium and aluminum as main components (Mg ₁₇ Al ₁₂ phase as a typical composition) is finely precipitated in the magnesium matrix by dynamic precipitation during plastic processing. .. Since the intermetallic compound of the Mg ₁₇ Al ₁₂ phase is precipitated in the matrix phase at a density equal to or higher than a certain level in a fine state, the strength of the magnesium alloy plastic working member 1 is increased without deteriorating the ductility. This is because the Vickers hardness of the Mg ₁₇ Al _12- phase intermetallic compound is also 350 to 600 (average value).

(Area ratio of intermetallic compounds)
Specifically, in the cross-sectional structure photograph of the magnesium alloy plastic working member 1 taken by a scanning electron microscope, the area ratio of the intermetallic compound (precipitation phase, representative composition Mg ₁₇ Al ₁₂ phase) having a particle size of 1 μm or less. However, it is preferably 2% or more.

The fact that the very fine intermetallic compound (precipitated phase, representative composition Mg ₁₇ Al ₁₂ phase) having a particle size of 1 μm or less has a certain ratio in the entire magnesium alloy plastic processed member 1. , The movement of dislocations in the matrix can be suppressed and the strength can be improved. In particular, the small particle size of the intermetallic compound (precipitation phase, representative composition: Mg ₁₇ Al ₁₂ phase) is unlikely to be the starting point of fracture, and deterioration of ductility can be suppressed. Furthermore, the area ratio of the intermetallic compound (precipitation phase) having a small particle size of 1 μm or less (the intermetallic compound (precipitation phase) having a particle size of 1 μm or less with respect to the total area of the cross-sectional structure photograph of the magnesium alloy plastic processed member 1). ) Is 2% or more, so that the strength is efficiently improved.

Further, the intermetallic compound (precipitated phase, representative composition: Mg ₁₇ Al ₁₂ phase) has a fine particle size, and the fine particle size of the intermetallic compound having a particle size of 1 μm or less is 2% or more. The bonding force of the magnesium alloy plastic processed member due to the intermetallic compound can be enhanced. Due to the high bonding force, not only the intermetallic compound but also the overall strength (strength against external pressure and external impact) becomes high. When the average particle size of the precipitated phase is 1 μm or less, dislocations are less likely to accumulate around the precipitated phase (stress concentration is less likely to occur), and even if the hardness of the precipitated phase is low (even if the Vickers hardness is 350 or less). This is because it does not become the starting point of destruction.

An intermetallic compound (precipitated phase) having a fine particle size of 1 μm or less is contained in the cross section of the magnesium alloy plastic processed member 1 including the matrix phase in an area of 2% or more, so that the metal is fine. The intermetallic acts as an overall strengthening agent. In addition, since the particle size of the intermetallic compound having a high area ratio that plays the role of this reinforcing agent is fine, stress concentration is less likely to occur around the intermetallic compound (precipitation phase). As a result, an excellent balance between strength and ductility is developed.

Further, since the metal compound (crystallization phase) has a certain hardness (Vickers hardness 350 to 600) or more, even if the particle size of the intermetallic compound (crystallization phase) is coarse (1 μm) or more. It is less likely to be the starting point of destruction. By superimposing the role of the precipitate in addition to the role of the crystallization phase, the strength of the magnesium alloy plastic working member 1 can be efficiently improved.

(Grain size of recrystallized mother phase)
The magnesium alloy plastic working member 1 contains a matrix containing magnesium as a main component. This matrix contains recrystallized grains generated when plastic working is applied, and the magnesium alloy plastic working member 1 contains recrystallized grains of the matrix.

Here, the average particle size of the matrix recrystallized grains of the magnesium alloy plastic working member 1 described in the first embodiment is less than 5 μm. When the average particle size of the recrystallized particles of the matrix is less than 5 μm, the recrystallized grains constituting the matrix are fine (not too large), and the matrix exhibits high strength against impact and stress. it can. In particular, since the recrystallized grains constituting the matrix are as fine as less than 5 μm, the magnesium alloy plastic working member 1 containing the recrystallized grains can increase the tensile strength when pulled.

Similarly, since the recrystallized grains constituting the matrix are fine, the magnesium alloy plastic working member 1 has a high elongation at break.

The average particle size of the matrix recrystallized grains is as fine as less than 5 μm because of the magnesium alloy plastic working member.
With respect to the whole, 8.0% by mass to 11.0% by mass of Al and
With respect to the whole, 0.0 mass% to 3.0 mass% Zn and
With respect to the whole, 0.5% by mass to 2.5% by mass of Ca,
Mn of 0.0% by mass to 0.6% by mass with respect to the whole,
One premise is that it consists of the rest of magnesium and an unavoidable mixture. This also applies to the Vickers hardness of the intermetallic compound (crystallization phase) containing Al ₂ Ca as a main component being 350 to 600 (average value).

The magnesium alloy plastic working member 1 contains a matrix phase and an intermetallic compound (crystallization phase and precipitation phase). A metal having an average particle size of the recrystallized particles of the parent phase constituting the matrix phase of less than 5 μm, a Vickers hardness of an intermetallic compound (crystallization phase) of 350 to 600, and a particle size of less than 1 μm. Combined with the fact that the area ratio of the intermetallic compound (precipitated phase) is 2% or more of the entire cross section, the magnesium alloy plastic processed member 1 can have high tensile strength and breaking elongation.

Due to its high tensile strength, the magnesium alloy plastic working member 1 can be suitably used for structural members and parts used in parts where a load or stress is easily applied. Further, by having a high breaking elongation, the magnesium alloy plastic working member 1 can be machined into various shapes. As a result, the magnesium alloy plastic working member 1 has both ease of processing and securing of strength, and can be used for structural members of transportation equipment, which have been considered difficult to use in the past.

Conventionally, iron, aluminum, etc. have been used for the structural members of this transportation equipment from the viewpoint of ease of processing and strength. On the other hand, the magnesium alloy plastic working member 1 containing magnesium as a main component has an advantage that it is lighter than iron or aluminum. Further, as described above, the magnesium alloy plastic working member 1 secures flame retardancy depending on the composition.

Combined with this flame retardancy, the magnesium alloy plastic working member 1 can be used as a structural member or a part even in a portion where heat is applied during use.

(Tension strength and breaking elongation)
As an example, the magnesium alloy plastic working member 1 of the present invention has a tensile strength of 340 MPa or more in a room temperature tensile test. Furthermore, it has a breaking elongation of 8% or more.

This is because having a tensile strength of 340 MPa or more can realize the same strength as parts and structural members in which iron, aluminum, etc. (including alloys thereof) are currently used. In particular, in the structural members of transportation equipment, deformation pressure and stress are strongly applied due to the characteristics of movement of transportation equipment. Or a shock is also applied. In this case, tensile stress and compressive stress are applied to the structural member. That is, it is necessary that the tensile pressure has a certain value or more when used for these structural members and parts. Having a tensile strength of 340 MPa or more in the room temperature tensile test makes it possible to replace the currently used iron and aluminum with magnesium alloy plastic working members.

In addition, there is a possibility that the structural member may be broken due to the application of such tensile stress or compressive stress. Since fracture leads to fracture, it is preferable that the flexibility to the stress leading to fracture is high. In addition, in order to process structural members and parts having various structures and shapes, it is necessary to undergo various processing. Flexibility in this process is also required. One of the criteria for showing flexibility against stress and machining is fracture elongation, and having a fracture elongation of 8% or more is sufficient when applied to general structural members and parts. In particular, the current structural members and parts in which iron and aluminum are used have a breaking elongation of this degree. Therefore, by having a breaking elongation of 8% or more, the magnesium alloy plastic member 1 of the present invention can be used for structural members and parts in which iron and aluminum (including alloys) have been conventionally used.

On the other hand, although the strength is not as high as that of iron or aluminum (tensile strength of 340 MPa or more), there are some structural members that require high elongation. For example, the inner plate and the outer plate of an automobile body do not need to have high strength, but high ductility is required because a complicated shape needs to be given by press molding.

The index required to apply the magnesium alloy to these parts is the breaking elongation, and by having a breaking elongation of 17% or more, structural members and parts (inner plates of automobiles and automobiles) where soft steel sheets have been conventionally used have been used. The magnesium alloy plastic member 1 of the present invention can also be used for the outer plate, etc.).

As described above, the magnesium alloy plastic working member 1 is subjected to high heat and high pressure (including impact) by having a tensile strength of 340 MPa or more and a breaking elongation of 8% or more in the room temperature tensile test. It can also be suitably used for structural members and parts of plastic working equipment. Further, in the tensile test, the magnesium alloy plastic working member 1 has a tensile strength of 310 MPa or more and a breaking elongation of 17% or more, so that the magnesium alloy plastic working member 1 can also be used for structural members and parts of equipment that can be imparted with high heat and complicated shapes. It can be suitably applied. By being able to replace conventional iron and aluminum, it is possible to reduce the weight and cost accordingly.

As described above, the magnesium alloy plastic working member according to the first embodiment can be suitably used for structural members and parts in fields where iron and aluminum have been conventionally used.

(Embodiment 2)

Next, the second embodiment will be described. In the second embodiment, the method for manufacturing the magnesium alloy plastic working member 1 described in the first embodiment will be described.

FIG. 1 is a flowchart showing a manufacturing process of a magnesium alloy plastic working member according to a second embodiment of the present invention. The magnesium alloy plastic working member 1 described in the first embodiment is manufactured using the flowchart of FIG. 1 as a basic manufacturing process.

First, in step ST1, a melting step is carried out in which the materials required for the magnesium alloy 2 are mixed and melted. Here, as shown in FIG. 2, the following materials required are charged into the melting container 100.

8.0% by mass to 11.0% by mass of Al, based on the whole
0.0% by mass to 3.0% by mass of Zn, based on the whole
0.5% by mass to 2.5% by mass of Ca, based on the whole
0.0% by mass to 0.6% by mass of Mn, based on the whole
The rest of magnesium.

FIG. 2 is a schematic view showing a melting step of melting a material according to the second embodiment of the present invention. Each material having the above-mentioned composition ratio is put into the melting container 100. The melting vessel 100 is heated at a temperature at which these melt, so that the melting vessel 100 melts. In the melting vessel 100, these materials are melted and stirred. By this stirring, a molten alloy is produced by uniformly mixing.

Next, in step ST2, the molten alloy produced in the melting vessel 100 is cooled and solidified. By cooling and solidifying, a magnesium alloy 2 having the above composition and composition ratio is produced. The magnesium alloy 2 at this stage has an ingot or other form.

Next, in step ST3, a predetermined plastic working is performed on the magnesium alloy 2. That is, the plastic working process is carried out. By plastic working in the plastic working step, the magnesium alloy plastic working member 1 described in the first embodiment can be obtained from the magnesium alloy 2 having a form such as an ingot.

As described above, the magnesium alloy plastic working member 1 is manufactured by using steps ST1 to ST3 as the basic manufacturing steps. The magnesium alloy plastic working member 1 obtained in this manufacturing process has the following characteristics as described in the first embodiment.

(Composition ratio)
The composition ratio is as follows.
8.0% by mass to 11.0% by mass of Al, based on the whole
0.0% by mass to 3.0% by mass of Zn, based on the whole
0.5% by mass to 2.5% by mass of Ca, based on the whole
0.0% by mass to 0.6% by mass of Mn, based on the whole
The rest of magnesium and an unavoidable mixture.

(Hardness of intermetallic compound)
The Vickers hardness of the intermetallic compound (crystallized product, representative composition: Al ₂ Ca) is 350 to 600 (average value). Having such hardness prevents the intermetallic compound from becoming too brittle or too sensitive to impact. As a result, the magnesium alloy plastic working member 1 is less likely to be broken or broken from the intermetallic compound (crystallized product) as a base point.

(Area ratio of fine intermetallic compounds)
In the cross-sectional structure photograph of the magnesium alloy plastic working member 1 taken by a scanning electron microscope, the area ratio of the intermetallic compound (precipitate, representative composition: Mg ₁₇ Al ₁₂ phase) having a particle size of 1 μm or less is the cross-sectional structure. It is 2% or more of the whole. Since the fine intermetallic compound (precipitate) having a particle size of 1 μm or less has an area ratio of 2% or more in the entire cross-sectional structure including the matrix, the strength is increased without deteriorating the ductility of the matrix. .. This is because the fineness makes it difficult for stress concentration to occur around the precipitate even if the hardness of the precipitate is low, and the brittleness and weakness to impact are reduced.

Further, when the area ratio of the intermetallic compound (precipitate) having a fine particle size is 2% or more, the strength of the magnesium alloy plastic working member 1 containing the precipitate is increased, and the tensile strength is increased.

(Average particle size of mother phase recrystallized grains)
The average particle size of the matrix recrystallized grains of the magnesium alloy plastic working member 1 is less than 5 μm. When the average particle size of the recrystallized matrix grains is as fine as less than 5 μm, the strength and ductility of the matrix itself are enhanced in a well-balanced manner.

Combined with the results with other properties, the magnesium alloy plastic working member 1 manufactured in the manufacturing process of FIG. 1 can achieve high strength and ductility.

(Strength and ductility)
The magnesium alloy plastic working member 1 manufactured in the manufacturing process of FIG. 1 has a tensile strength of 340 MPa or more in a room temperature tensile test. Furthermore, it has a breaking elongation of 8% or more. By having such tensile strength and breaking elongation, it is possible to exhibit ease of processing, strength against pressure and impact, and ductility.

Next, in the manufacturing process, an additional process will be described.

(Solution treatment)
FIG. 3 is a schematic diagram illustrating the solution treatment according to the second embodiment of the present invention. The solution treatment in step ST4 is carried out between step ST2 and step ST3 in FIG.

Magnesium alloy 2 is produced by the cooling step of step ST2. In FIG. 3, the magnesium alloy 2 melted and cooled in the melting vessel 100 is shown. The magnesium alloy 2 produced through the melting step and the cooling step has a form such as an ingot or a billet.

In step ST4, the magnesium alloy 2 undergoes a solution treatment. In the solution treatment, the magnesium alloy is heated. At this time, solution treatment is performed by heating at a predetermined temperature.

The predetermined temperature is preferably 450 ° C to 525 ° C. This is because the hardness of the intermetallic compound (crystallized product, representative composition: Al ₂ Ca phase) as described in the first embodiment can be realized by the solution heat treatment in the predetermined temperature range. Further, by undergoing the heat treatment at the above temperature, a crystallized product containing Al or Mg as a main component (representative composition: Mg ₁₇ Al ₁₂ phase) can be solid-solved in the matrix phase.

By the solution treatment, the intermetallic compound (crystallized product, representative composition: Mg ₁₇ Al ₁₂ phase) is solid-solved in the matrix phase. In particular, by the solution treatment at a heating temperature of 450 ° C. to 525 ° C., such an action is surely realized, and it becomes easy to form as a fine precipitation phase in the subsequent plastic working. Further, by the solution treatment at a heating temperature of 450 ° C. to 525 ° C., the defects inside the intermetallic compound (crystallized product, representative composition: Al ₂ Ca phase) are effectively eliminated by diffusion, and the hardness is increased. To do.

Further, the predetermined temperature in the solution treatment is preferably 450 ° C. to 525 ° C., but more preferably 490 ° C. to 520 ° C., which is narrowed down. By performing the solution treatment at the narrowed-down predetermined temperature, the intermetallic compound (crystallized product, representative composition: Mg ₁₇ Al ₁₂ phase) is solid-solved, and the intermetallic compound (crystallized product, representative composition: Al) is dissolved. _This is because the increase in hardness of the ₂ Ca phase) proceeds in a better direction.

Further, it is more preferable that the solution treatment is performed at a predetermined temperature of 510 ° C.

(Plastic working)
In step ST3, the magnesium alloy 2 is subjected to a plastic working step. By the plastic working in this plastic working step, the magnesium alloy plastic working member 1 is obtained.

As the plastic working, any one of extrusion, rolling, forging and drawing is applied. This is because any of these processes is appropriate for processing the magnesium alloy 2 into a certain form. In addition, after being processed into a certain form, either extrusion processing, rolling processing, forging processing, or drawing processing is performed according to the characteristics of structural members and parts obtained by processing such as final molding. Applies.

By any of these (possibly combined) plastic working, the magnesium alloy 2 is machined into the magnesium alloy plastic working member 1. By being in the processed state, even if various properties are insufficient in the case of the magnesium alloy 2, the magnesium alloy plastic working member 1 after plastic working realizes the various properties described in the first embodiment. it can.

That is, the hardness of the intermetallic compound (crystallized product, representative composition: Al ₂ Ca phase), the area ratio of the intermetallic compound having a fine particle size (precipitate, representative composition: Mg ₁₇ Al ₁₂ phase), and the matrix recrystallization. A magnesium alloy plastic processed member 1 that realizes the characteristics of the average grain size of grains can be manufactured. As a result, a magnesium alloy plastic working member 1 having a tensile strength of 340 MPa or more and a breaking elongation of 8% or more in a room temperature tensile test is produced.

(Heating process)
FIG. 4 is a schematic view showing the extrusion process according to the second embodiment of the present invention. As described above, plastic working includes extrusion, rolling, forging, drawing and the like. Of these, the magnesium alloy 2 produced through step ST4 may be extruded to be an extruded material.

FIG. 4 shows a state in which the magnesium alloy 21 in the form of a billet is pushed into the extrusion die 10 and is extruded. The extrusion die 10 has an inner diameter that gradually tapers. The magnesium alloy 21 is pressed from the upper part of the inner diameter. Pressure is applied when pressing.

The arrow in FIG. 4 indicates the application (pressurization) of this pressure.

By being pressurized, the magnesium alloy 21 is pushed into the internal space 11 of the extrusion die 10. In the process of being pushed into the internal space 11, the magnesium alloy 21 is processed into a shape that matches the shape and inner diameter of the internal space 11. That is, the magnesium alloy plastic working material 1 is obtained by the extrusion die 10 (the plastic working is the extrusion work).

At this time, it is preferable that each of the magnesium alloy 21 used for the extrusion process and the die 10 for the extrusion process is heated to 250 ° C. to 300 ° C. before the extrusion process. FIG. 4 shows a state in which each of the magnesium alloy 21 and the extrusion die 10 is heated. The heating is preferably in the range of 250 ° C to 300 ° C.

Before extrusion, the magnesium alloy 21 to be extruded and the die 10 for extrusion are heated in the range of 250 ° C. to 300 ° C., so that the magnesium alloy plastic working member 1 manufactured by extrusion is , Can have the properties described in Embodiment 1.

That is, by setting the above processing temperature, the area ratio of the fine intermetallic compound (precipitate, representative composition: Mg ₁₇ Al ₁₂ phase) and the average particle size of the recrystallized matrix grains can be more reliably reduced. it can. By this realization, the extruded magnesium alloy plastic working member 1 to be manufactured can surely have a tensile strength of 340 MPa or more and a breaking elongation of 8% or more in a room temperature tensile test.

According to the manufacturing method according to the second embodiment as described above, the magnesium alloy plastic working member 1 can be used even in the structural members and parts in the field where iron and aluminum have been conventionally used. It can be replaced. By this replacement, a lighter weight and lower cost device can be realized.

(Embodiment 3)

The magnesium alloy plastic working member 1 described in the first and second embodiments is used for various purposes. In particular, it can be used for parts and structural members of various devices such as electronic devices, machine tools, transportation devices, and precision devices. In particular, it can be suitably used for a structural member that needs to cope with a load and a load and requires strength and durability.

For example, it can be used for a chassis or body of a transportation device such as an automobile, or a structural member such as a frame. It can be used for structural members such as chassis, body, and frame of aircraft and ships.

Since these structural members form the skeleton of the device, they require strength and durability, but by reducing the weight, the weight of the entire device can be reduced. In particular, the step-up of weight reduction is an extremely large factor.

Since it can be used for structural members such as chassis, body, and frame, the weight of the equipment can be reduced, and the operating cost and energy of the equipment can be reduced.

These can also be used because they are magnesium alloy plastic working members 1 having the characteristics as described in the first and second embodiments in addition to the flame retardancy.

(Embodiment 4)

Next, the fourth embodiment will be described. In the fourth embodiment, the results of experiments performed on the plastically worked members of the magnesium alloy described in the first to third embodiments will be described.

FIG. 5 is a table showing the experimental results regarding the difference in temperature of the solution treatment in the fourth embodiment of the present invention. The table of FIG. 5 shows the results of Comparative Examples 1 to 5 and Examples 1 to 11 depending on the composition ratio and the difference in temperature in the solution treatment.

Both Comparative Examples 1 to 5 and Examples 1 to 11 are magnesium alloys produced with the respective compositions and composition ratios, and were subjected to solution treatment at the corresponding temperatures before plastic working. It is a thing. Further, the plastic working is extruding, and the extruding die used for extruding is extruded at a predetermined temperature corresponding to each.

(About the production of each example)
The manufactured products will be described below.

(Comparative Example 1)
The plastic working member of the magnesium alloy of Comparative Example 1 is
9.0 mass% Al,
0.7% by mass Zn,
2.0% by mass Ca,
0.2% by mass Mn,
Manufactured with the rest of magnesium and an unavoidable mixture,
No solution treatment,
The processing temperature in extrusion is 280 ° C,
It is a plastic working member of magnesium alloy manufactured in.

(Comparative Example 2)
The plastic working member of the magnesium alloy of Comparative Example 2 is
12.0% by mass Al,
0.7% by mass Zn,
2.0% by mass Ca,
0.2% by mass Mn,
Manufactured with the rest of magnesium and an unavoidable mixture,
The treatment temperature in the solution treatment is 480 ° C,
The processing temperature in extrusion is 280 ° C,
It is a plastic working member of magnesium alloy manufactured in.

(Comparative Example 3)
The plastic working member of the magnesium alloy of Comparative Example 3 is
6.0% by mass Al,
0.7% by mass Zn,
2.0% by mass Ca,
0.2% by mass Mn,
Manufactured with the rest of magnesium and an unavoidable mixture,
The treatment temperature in the solution treatment is 420 ° C,
The processing temperature in extrusion is 300 ° C,
It is a plastic working member of magnesium alloy manufactured in.

(Comparative Example 4)
The plastic working member of the magnesium alloy of Comparative Example 4 is
9.0 mass% Al,
0.7% by mass Zn,
2.0% by mass Ca,
0.2% by mass Mn,
Manufactured with the rest of magnesium and an unavoidable mixture,
The treatment temperature in the solution treatment is 420 ° C,
The processing temperature in extrusion is 350 ° C,
It is a plastic working member of magnesium alloy manufactured in.
(Comparative Example 5)
The plastic working member of the magnesium alloy of Comparative Example 5 is
6.0% by mass Al,
0.7% by mass Zn,
2.0% by mass Ca,
0.2% by mass Mn,
Manufactured with the rest of magnesium and an unavoidable mixture,
The treatment temperature in the solution treatment is 510 ° C,
The processing temperature in extrusion is 280 ° C,
It is a plastic working member of magnesium alloy manufactured in.

(Example 1)
The plastic working member of the magnesium alloy of Example 1 is
9.0 mass% Al,
0.7% by mass Zn,
2.0% by mass Ca,
0.2% by mass Mn,
Manufactured with the rest of magnesium and an unavoidable mixture,
The treatment temperature in the solution treatment is 450 ° C,
The processing temperature in extrusion is 280 ° C,
It is a plastic working member of magnesium alloy manufactured in.

(Example 2)
The plastic working member of the magnesium alloy of Example 2 is
9.0 mass% Al,
0.7% by mass Zn,
2.0% by mass Ca,
0.2% by mass Mn,
Manufactured with the rest of magnesium and an unavoidable mixture,
The treatment temperature in the solution treatment is 480 ° C,
The processing temperature in extrusion is 280 ° C,
It is a plastic working member of magnesium alloy manufactured in.

(Example 3)
The plastic working member of the magnesium alloy of Example 3 is
9.0 mass% Al,
0.7% by mass Zn,
2.0% by mass Ca,
0.2% by mass Mn,
Manufactured with the rest of magnesium and an unavoidable mixture,
The treatment temperature in the solution treatment is 510 ° C,
The processing temperature in extrusion is 280 ° C,
It is a plastic working member of magnesium alloy manufactured in.

(Example 4)
The plastic working member of the magnesium alloy of Example 4 is
9.0 mass% Al,
0.7% by mass Zn,
2.0% by mass Ca,
0.2% by mass Mn,
Manufactured with the rest of magnesium and an unavoidable mixture,
The treatment temperature in the solution treatment is 525 ° C,
The processing temperature in extrusion is 280 ° C,
It is a plastic working member of magnesium alloy manufactured in.

(Example 5)
The plastic working member of the magnesium alloy of Example 5 is
11.0% by mass Al,
0.7% by mass Zn,
2.0% by mass Ca,
0.2% by mass Mn,
Manufactured with the rest of magnesium and an unavoidable mixture,
The treatment temperature in the solution treatment is 480 ° C,
The processing temperature in extrusion is 280 ° C,
It is a plastic working member of magnesium alloy manufactured in.

(Example 6)
The plastic working member of the magnesium alloy of Example 6 is
9.0 mass% Al,
0.7% by mass Zn,
0.5% by mass Ca,
0.2% by mass Mn,
Manufactured with the rest of magnesium and an unavoidable mixture,
The treatment temperature in the solution treatment is 480 ° C,
The processing temperature in extrusion is 280 ° C,
It is a plastic working member of magnesium alloy manufactured in.

(Example 7)
The plastic working member of the magnesium alloy of Example 7 is
9.0 mass% Al,
0.7% by mass Zn,
2.5% by mass Ca,
0.2% by mass Mn,
Manufactured with the rest of magnesium and an unavoidable mixture,
The treatment temperature in the solution treatment is 510 ° C,
The processing temperature in extrusion is 280 ° C,
It is a plastic working member of magnesium alloy manufactured in.

(Example 8)
The plastic working member of the magnesium alloy of Example 8 is
7.0% by mass Al,
0.7% by mass Zn,
2.0% by mass Ca,
0.2% by mass Mn,
Manufactured with the rest of magnesium and an unavoidable mixture,
The treatment temperature in the solution treatment is 510 ° C,
The processing temperature in extrusion is 280 ° C,
It is a plastic working member of magnesium alloy manufactured in.

(Example 9)
The plastic working member of the magnesium alloy of Example 9 is
8.0% by mass Al,
0.7% by mass Zn,
2.0% by mass Ca,
0.2% by mass Mn,
Manufactured with the rest of magnesium and an unavoidable mixture,
The treatment temperature in the solution treatment is 510 ° C,
The processing temperature in extrusion is 280 ° C,
It is a plastic working member of magnesium alloy manufactured in.

(Example 10)
The plastic working member of the magnesium alloy of Example 10 is
10.0 mass% Al,
0.7% by mass Zn,
2.0% by mass Ca,
0.2% by mass Mn,
Manufactured with the rest of magnesium and an unavoidable mixture,
The treatment temperature in the solution treatment is 495 ° C,
The processing temperature in extrusion is 280 ° C,
It is a plastic working member of magnesium alloy manufactured in.

Here, the extrusion process was performed under the following conditions.

An alloy casting material produced according to the composition of each of the above examples,
1 No solution treatment (Comparative Example 1)
2 After 48 hours of solution treatment at 420 ° C, water cooling (example of solution treatment at 420 ° C)
3 First, after a solution treatment at 420 ° C. for 48 hours, it is cooled with water. This is followed by a 48-hour solution treatment at 450 ° C to 525 ° C and then water cooling (example of solution treatment at 450 ° C to 525 ° C).
The solution treatment is performed in any of the above (one of 1 to 3 is performed depending on the temperature of the solution treatment).

The alloy obtained through this solution treatment is a billet material, and the billet has a diameter (38 to 39) × a height (35 to 41) mm.

The extrusion die used for extrusion processing has a diameter of 40 mm.

The extrusion ratio is 44 (40 mm in diameter is narrowed down to 6 mm in diameter).

The ram speed at the time of extrusion is 5 mm / min (material extrusion speed: 222 mm / min).

The extrusion temperature corresponds to the processing temperature in the extrusion process of each example.

For each of the plastically worked members of the magnesium alloy of each example produced in this way, the Vickers hardness and mechanical properties (tensile strength, proof stress, elongation at break) of the intermetallic compound of Al ₂ Ca were measured under the following conditions. did.

(Vickers hardness measurement conditions)
Equipment: Micro Vickers hardness tester (Mitutoyo HM-200)
Load: 0.0005kgf
Load time: 10 seconds Measurement points: 5 to 10 points Measurement surface: Cross section parallel to the extrusion direction

(Measurement conditions for mechanical properties)
Equipment: Instron universal testing machine (INSTRON 5565Q6662)
Specimen parallel part dimensions: diameter 2.5 mm, length 14 mm (JIS14A compliant)
Crosshead speed: 2 mm / min (initial strain rate: 2.4 x 10 ^-3 S ^-1 )
Strain gauge used

Based on the above measurement conditions, the Vickers hardness and mechanical properties of Comparative Examples 1 to 5 and Examples 1 to 11 are as shown in FIG.

(Comparative Example 1)
Vickers hardness: 186-268 (average: 236)
Tensile strength: 373 MPa
Proof stress: 284 MPa
Breaking elongation: 11%

(Comparative Example 2)
Vickers hardness: 397-801 (average: 617)
Tensile strength: 393 MPa
Proof stress: 277 MPa
Breaking elongation: 4%

(Comparative Example 3)
Vickers hardness: 212-295 (average: 259)
Tensile strength: 317 MPa
Proof stress: 208 MPa
Breaking elongation: 14%

(Comparative Example 4)
Vickers hardness: 228-310 (average: 274)
Tensile strength: 316 MPa
Proof stress: 208 MPa
Breaking elongation: 12%
(Comparative Example 5)
Vickers hardness: 344-425 (average: 379)
Tensile strength: 318 MPa
Proof stress: 210 MPa
Breaking elongation: 19%

(Example 1)
Vickers hardness: 337-572 (average: 415)
Tensile strength: 359 MPa
Proof stress: 246 MPa
Breaking elongation: 15%

(Example 2)
Vickers hardness: 386-583 (average: 465)
Tensile strength: 366 MPa
Proof stress: 241 MPa
Breaking elongation: 16%

(Example 3)
Vickers hardness: 377-566 (average: 483)
Tensile strength: 367 MPa
Proof stress: 265 MPa
Breaking elongation: 17%

(Example 4)
Vickers hardness: 397-658 (average: 516)
Tensile strength: 344 MPa
Proof stress: 236 MPa
Breaking elongation: 19%

(Example 5)
Vickers hardness: 361-688 (average: 565)
Tensile strength: 386 MPa
Proof stress: 277 MPa
Breaking elongation: 8%

(Example 6)
Vickers hardness: 360-577 (average: 470)
Tensile strength: 384 MPa
Proof stress: 240 MPa
Breaking elongation: 14%

(Example 7)
Vickers hardness: 395-682 (average: 475)
Tensile strength: 358 MPa
Proof stress: 241 MPa
Breaking elongation: 15%

(Example 8)
Vickers hardness: 513-612 (average: 573)
Tensile strength: 317 MPa
Proof stress: 202 MPa
Breaking elongation: 17%

(Example 9)
Vickers hardness: 395-602 (average: 513)
Tensile strength: 342 MPa
Proof stress: 221 MPa
Break elongation: 18%

(Example 10)
Vickers hardness: 436-516 (average: 486)
Tensile strength: 379 MPa
Proof stress: 265 MPa
Breaking elongation: 14%

From the above experimental results, the composition ratio of the magnesium alloy is as described in the first embodiment.

With respect to the whole, 8.0% by mass to 11.0% by mass of Al and
With respect to the whole, 0.0 mass% to 3.0 mass% Zn and
With respect to the whole, 0.5% by mass to 2.5% by mass of Ca,
Mn of 0.0% by mass to 0.6% by mass with respect to the whole,
It was confirmed that the remaining magnesium and an unavoidable mixture were appropriate.

It was also confirmed that the treatment temperature in the solution treatment is preferably 450 ° C. to 525 ° C. Furthermore, it was also confirmed that the processing temperature of the extrusion die in the extrusion process is preferably 250 ° C. to 300 ° C. By satisfying these conditions, both strength and ductility can be achieved.

At this time, the Vickers hardness of the intermetallic compound (crystallized product, representative composition: Al ₂ Ca phase) is 350 to 600 on average, the tensile strength is 340 MPa or more, and the elongation at break is 8. It was confirmed in the examples that it was% or more.

(Confirmation by SEM photo)
In addition, in comparison between Examples and Comparative Examples, it was confirmed from SEM photographs that a magnesium alloy composition-processed member having both strength and ductility was realized.

FIG. 6 is an SEM photograph (cross-sectional structure photograph) of an example and a comparative example in the fourth embodiment of the present invention. FIG. 6A is an SEM photograph of the composition processing member of the magnesium alloy of Comparative Example 3 described in FIG. FIG. 6C shows an intermetallic compound of a precipitate (representative composition: Mg ₁₇ Al ₁₂ phase) having a diameter of 1 μm or less in the cross section of the magnesium alloy composition processed member analyzed by the SEM photograph of FIG. 6 (A). It is a photograph in which the part is surrounded by a frame.

FIG. 6B is an SEM photograph (cross-sectional structure photograph) of Example 3 described in FIG. FIG. 6 (D) shows an intermetallic compound of a precipitate (representative composition: Mg ₁₇ Al ₁₂ phase) having a diameter of 1 μm or less in the cross section of the magnesium alloy composition processed member analyzed by the SEM photograph of FIG. 6 (B). It is a photograph in which the part is surrounded by a frame.

When each of Comparative Example 3 and Example 3 was analyzed using the image analysis software of Image-Pro Analyzer (ver. 7), in Comparative Example 3, a precipitate having a particle size of 1 μm or less (representative composition: Mg ₁₇ Al ₁₂ phase) was analyzed. ), The area ratio of the intermetallic compound is 1.9%, which is less than 2%. The average particle size is 0.41 μm. On the other hand, in Example 3, the area ratio of the intermetallic compound of the precipitate having a particle size of 1 μm or less (representative composition: Mg ₁₇ Al ₁₂ phase) is 6.6%. The average particle size is 0.26 μm.

The average value of the Vickers hardness of Comparative Example 3 is 259, and the tensile strength is 317 MPa, which is not sufficient in terms of strength. On the other hand, the average value of the Vickers hardness of Example 3 is 483, and the tensile strength is 367 MPa. Sufficient in strength.

As described above, in the comparative example and the example, the particle size of the intermetallic compound (precipitate, representative composition: Mg ₁₇ Al ₁₂ phase) and the area ratio of the particle size of 1 μm or less are determined depending on whether or not the strength can be sufficiently realized. Was confirmed to be required to be 2% or more. As a premise of this, it was confirmed that the Vickers hardness of the intermetallic compound (crystallized product, representative composition: Al ₂ Ca phase) is hard, so that both strength and ductility can be achieved.

From the above experimental results, it was possible to confirm the relationship between the manufacturing conditions and the results of the magnesium alloy composition processed members described in the first to third embodiments, and to confirm the reason why both strength and ductility can be achieved.

In addition, FIG. 7 shows a photograph when the Vickers hardness of an intermetallic compound (crystallized product, representative composition: Al ₂ Ca phase) was measured. As shown in FIG. 7, the Vickers hardness of the intermetallic compound (crystallized product, representative composition: Al ₂ Ca phase) indicated by the arrow was measured in each of Comparative Examples and Examples. The measured Vickers hardness was 247 and 564, respectively. It can be confirmed that the examples clearly show smaller indentations as compared with the comparative examples, and show high hardness.

The plastic working members of the magnesium alloy described in the first to fourth embodiments are an example for explaining the gist of the present invention, and include deformation and modification within a range not deviating from the gist of the present invention.

10 Extrusion die 11 Internal space 21 Magnesium alloy

Claims (10)

With respect to the whole, 8.0% by mass to 11.0% by mass of Al and
With respect to the whole, 0.0 mass% to 3.0 mass% Zn and
With respect to the whole, 0.5% by mass to 2.5% by mass of Ca,
Mn of 0.0% by mass to 0.6% by mass with respect to the whole,
Consists of the rest of magnesium and unavoidable impurities
An extruded member of a magnesium alloy having an average Vickers hardness of an intermetallic compound composed of an Al ₂ Ca phase of 350 to 600. The extruded member of a magnesium alloy according to claim 1, wherein an intermetallic compound composed of Mg ₁₇ Al ₁₂ phases is precipitated in the magnesium matrix. The first or second claim, wherein the area ratio of the intermetallic compound having a particle size of 1 μm or less is 2% or more in a cross-sectional structure photograph of the extruded member of the magnesium alloy taken by a scanning electron microscope. Extruded member of magnesium alloy. The average particle size of the magnesium matrix recrystallized grains of extrusion member magnesium alloy is less than 5 [mu] m, extrusion member magnesium alloy according to any of claims 1 to 3. The magnesium alloy extruded member according to any one of claims 1 to 4, which has a tensile strength of 340 MPa or more and a breaking elongation of 8% or more in a room temperature tensile test. A structural member used for a predetermined purpose by using the magnesium alloy extruded member according to any one of claims 1 to 5 . The structural member according to claim 6 , wherein the predetermined use is any of electronic equipment, precision equipment, machine tools and transportation equipment. With respect to the whole, 8.0% by mass to 11.0% by mass of Al and
With respect to the whole, 0.0 mass% to 3.0 mass% Zn and
With respect to the whole, 0.5% by mass to 2.5% by mass of Ca,
Mn of 0.0% by mass to 0.6% by mass with respect to the whole,
A melting process in which the remaining magnesium and unavoidable impurities are melted,
A cooling step of cooling and solidifying the molten alloy obtained by melting to obtain a magnesium alloy,
And a extrusion step of performing a predetermined extrusion into the magnesium alloy,
The Vickers hardness of the intermetallic compound composed of the Al ₂ Ca phase is 350 to 600.
A method for manufacturing a magnesium alloy extrusion member, wherein the magnesium alloy before extrusion further includes a solution step by heating at 450 ° C. to 525 ° C. In the cross-sectional structure photograph of the extruded member of the magnesium alloy taken by a scanning electron microscope, the area ratio of the intermetallic compound composed of the Mg ₁₇ Al ₁₂ phase having a particle size of 1 μm or less is 2% or more. The method for manufacturing a magnesium alloy extruded member according to claim 8 . Before the extrusion, the magnesium alloy and extrusion mold is a pre-heating step is heated to 250 ° C. to 300 ° C., further comprising, a manufacturing method of the extrusion member 9. Symbol mounting of magnesium alloy.