WO2006134980A1

WO2006134980A1 - Raw magnesium-alloy powder material, magnesium alloy with high proof stress, process for producing raw magnesium-alloy powder material, and process for producing magnesium alloy with high proof stress

Info

Publication number: WO2006134980A1
Application number: PCT/JP2006/311952
Authority: WO
Inventors: Katsuyoshi Kondoh; Mitsuhiro Goto; Hideaki Fukui; Kantaro Kaneko; Shuji Shiozaki; Katsuhito Itakura
Original assignee: Gohsyu Co., Ltd.; Kurimoto, Ltd.
Priority date: 2005-06-16
Filing date: 2006-06-14
Publication date: 2006-12-21
Also published as: KR20080028362A; CN101193715A; CN101193715B; EP1897638A4; US20090263268A1; JP2006348349A; EP1897638A1

Abstract

A raw magnesium-alloy powder material obtained by subjecting a starting-material powder having a relatively large crystal grain diameter to a plastic working in which the powder is passed through a pair of rolls to cause it to undergo compressive deformation or shear deformation and thereby make the crystal grain diameter relatively small. The starting-material powder is a magnesium alloy powder in which a fine intermetallic compound (21) has been precipitated/dispersed in a base (20) by a heat treatment. In the magnesium alloy powder which has undergone the plastic working, there are work strains (22) around the intermetallic compound (21) precipitated. The magnesium alloy powder which has undergone the plastic working has a maximum size of 10 mm or smaller and a minimum size of 0.1 mm or larger, and the magnesium particles constituting the base (20) have a maximum crystal grain diameter of 20 µm or smaller.

Description

Specification

MAGNESIUM ALLOY POWDER RAW MATERIAL, HIGH MAGNETIC RESISTANCE ALLOY, MAGNESIUM ALLOY

Technical field

TECHNICAL FIELD [0001] The present invention relates to a magnesium alloy powder raw material, a magnesium alloy produced using the powder raw material, and a production method thereof, and particularly relates to a magnesium alloy that achieves both high yield strength and elongation and a production method thereof. is there.

Background art

[0002] Magnesium (hereinafter referred to as Mg) alloy, which is the lightest of industrial metal materials, uses its light weight effect to produce sports equipment, home appliances, aerospace equipment, and other machinery. Widely used for parts. On the other hand, in order to apply Mg alloys to products and parts that require high reliability such as automobile parts, further increase in strength is required. In particular, there is a strong demand for improved proof stress in component design, and at the same time, it is necessary to achieve high elongation (toughness). In other words, by realizing high yield strength and high elongation, it is possible to replace the current lightweight aluminum alloy.

[0003] It is already known that refinement of crystal grains and dispersion strengthening of fine intermetallic compounds are effective in improving the strength of Mg alloys. In particular, the manufacturing method that uses Mg alloy powder as the starting material and compacts and solidifies it can form a finer structure than the melting and forging method, and is more effective in increasing strength. It can be called a manufacturing process.

[0004] For example, a force for producing a high-strength Mg alloy using a rapid solidification process has been proposed. This method is not practical for the following reasons.

[0005] (A) High strength results in low elongation of several percent.

[0006] (B) Since the starting material powder has a particle size as small as several tens to hundreds of microns, there is a problem of safety in the handling process, a problem of low yield, and addition of an expensive element. However, there is a problem of economic efficiency when the cost increase is induced.

[0007] On the other hand, various investigations have been proposed that use cutting powder discharged when cutting an Mg alloy material as a starting material, and compact this powder into a solid to produce an Mg alloy. For example, JP-A-2-182806 describes a method of extruding after solidifying the Mg alloy powder by hot pressing, and JP-A-5-320715 discloses forming and extruding the Mg alloy powder. How to do is described.

[0008] In addition, in the "Method for producing a magnesium alloy member" described in JP-A-5-306404, an aluminum-containing Mg alloy powder that has been subjected to T6 heat treatment (solution heat treatment + aging heat treatment) is used. A method of extruding after compacting has been proposed. In the manufacturing method disclosed here, when solidifying an Mg alloy cutting powder containing an appropriate amount of aluminum (A1), it has excellent mechanical properties by extracting the effects of both T6 heat treatment and extrusion. It is characterized by the creation of Mg alloy members. The effect of T6 heat treatment is to uniformly disperse the fine intermetallic compound Mg A1 in the base of the extruded Mg alloy.

17 12

The effect of the extrusion process is to refine the crystal grains constituting the base of the extruded Mg alloy. As a result, for example, described in ASTM standards, Al: 7.8 to 9.2 wt%, manganese (Mn): 0.12 to 0.35 wt%, zinc (Zn): 0.2 to 0 · 8% by weight, Mg: remainder, AZ80 Magnesium alloy with the following composition: T6 heat-treated with cutting powder made by molding · Extrusion Mg alloy obtained at room temperature Tensile strength is 3 82MPa and elongation is 27%. On the other hand, when T6 heat treatment is not applied, tensile strength is reported to be 330 MPa and elongation is 15%. .

[0009] However, in the Mg alloy member manufacturing method described in JP-A-5-306404, the proof stress of the extruded material is 196 MPa when T6 heat treatment is performed. When it is not applied, it is reported that it is 200 MPa, and the effect of improving tensile strength is not recognized. The cause is considered as follows. Compared with the Mg alloy crystal grains (50-700 μm) produced by the conventional melting * forging method, recrystallization occurs and the crystal grains are refined by the extrusion process. Considering the data disclosed so far, it is about 10 to 20 xm. In order to improve the tensile strength, it is necessary to further refine the crystal grains. Based on the data disclosed so far, for example, miniaturization to 1 to 5 μm or less is effective in improving the resistance to light. An Mg alloy having such a fine crystal grain size cannot be realized only by a manufacturing method in which a T6 heat-treated cutting powder is compacted and extruded. [0010] In addition, the intermetallic compound Mg A1, which was precipitated and dispersed in the substrate by T6 heat treatment, was extruded.

There is a limit to the level that can be refined by plastic deformation by extrusion, and in order to improve resistance, further refinement of intermetallic compounds is required. Fine and uniform dispersion of multiple intermetallic compounds is required.

Disclosure of the invention

An object of the present invention is to provide a magnesium alloy that achieves both high yield strength and elongation, and a method for producing the same.

Another object of the present invention is to provide a magnesium alloy powder raw material used for producing the magnesium alloy and a method for producing the same.

[0013] The magnesium alloy powder raw material according to the present invention is obtained by subjecting a starting raw material powder having a relatively large crystal grain size to plastic deformation by compressing or shearing it through a pair of rolls. It has a relatively small crystal grain size and is characterized by the following. That is, the starting material powder is a magnesium alloy powder in which fine intermetallic compounds are precipitated and dispersed in the substrate by heat treatment. In the magnesium alloy powder after plastic working, there is a working strain around the precipitated intermetallic compound. The maximum size of the magnesium alloy powder after plastic working is 10 mm or less, and the minimum size is 0.1 mm or more. The maximum crystal grain size of the magnesium particles constituting the base of the magnesium alloy powder after plastic molding is 20 μm or less.

Preferably, the intermetallic compound is Mg Al, Al Ca, Mg Si, MgZn, Al Re (Re: ¾r

17 12 2 2 2 3 Earth element), at least one compound selected from the group consisting of Al Re and Al Mn

11 3 6

It is. Preferably, the maximum particle size of the intermetallic compound is 5 x m or less, more preferably 2 x m or less.

[0015] Preferably, the maximum crystal grain size of magnesium particles constituting the base of the magnesium alloy powder is 10 x m or less.

[0016] A high-magnesium-resistant magnesium alloy according to the present invention is obtained by compacting a magnesium alloy powder raw material having the above-described characteristics and then extruding it, and has the following characteristics. Yes. That is, the maximum grain size of the magnesium particles constituting the alloy substrate is 10 μm or less, and the tensile strength at room temperature is 250 MPa or more. [0017] Preferably, the maximum crystal grain size force of the magnesium particles constituting the base of the magnesium alloy is ¾ μ μη or less, and the tensile strength at room temperature is 350 MPa or more.

[0018] Preferably, Mg Al, Al Ca, Mg Si, MgZn, A in the base of the magnesium alloy

17 12 2 2 2

1 At least one selected from the group consisting of Re (Re: rare earth elements), Al Re and Al Mn

3 11 3 6

Two intermetallic compounds are deposited and dispersed.

[0019] Preferably, the magnesium alloy contains strontium (eg, zirconium), an active metal element selected from the group consisting of scandium (Sc) and titanium (Ti) in an amount of 0.5% to 4% on a weight basis. Contains the following.

In the method for producing a magnesium alloy powder raw material according to the present invention, the crystal grain size of the magnesium particles constituting the substrate of the starting raw material powder is reduced by subjecting the starting raw material powder to a plastic case. This is a method of miniaturization and has the following characteristics. That is, a magnesium alloy powder in which fine intermetallic compounds are precipitated and dispersed in the substrate by heat treatment is prepared as a starting material powder. The plastic working is a plastic working in which the starting raw material powder is passed through a pair of rolls and subjected to compression deformation or shear deformation to impart processing strain around the intermetallic compound. The plastic working is repeated until the maximum size of the powder is 10 mm or less, the minimum size is 0.1 mm or more, and the maximum crystal grain size of the magnesium particles constituting the powder substrate is 20 μm or less.

In one embodiment, the step of preparing a magnesium alloy powder as a starting raw material powder includes preparing a magnesium alloy ingot by a forging method, solution treating the magnesium alloy ingot, and subsequently aging heat treatment. To deposit and disperse fine intermetallic compounds in the base of the ingot, and to remove the magnesium alloy powder from the ingot by machining. Preferably, when performing the above-described plastic cache, the temperature of the starting raw material powder to be introduced and the surface temperature of the roll in contact with the starting raw material powder are set to be equal to or lower than the temperature of the aging heat treatment.

[0022] A method for producing a high-magnesium-resistant magnesium alloy according to the present invention includes a step of obtaining a compacted body by pressing a magnesium alloy powder raw material having the above-described characteristics in a state where the mold is filled, and magnesium The process of heating the compacted compact of the alloy at a temperature of 150 ° C or higher and 450 ° C or lower, and immediately after the heating, the compacted compact of the magnesium alloy is extruded to form the magnesium composite. A process for producing gold.

[0023] Preferably, the maximum grain size of magnesium particles constituting the base of the magnesium alloy is not more than SlOm, and the tensile resistance at room temperature is not less than 50MPa. More preferably, the magnesium alloy powder compact is heated at a temperature of 200 ° C to 350 ° C. Brief Description of Drawings

FIG. 1 is an illustrative view showing a roller compactor device.

FIG. 2 is an illustrative view showing a state in which processing strain exists around an intermetallic compound.

[Fig. 3] Structure photograph of AZ91D ingot, (a) Structure photograph after fabrication, (b) Structure photograph after solution heat treatment, (c) Structure after T6 heat treatment (solution + aging heat treatment) The photo is shown.

FIG. 4 is an enlarged structural photograph of the structure after T6 heat treatment.

[Fig. 5] Structure photograph of AZ91D powder that has been subjected to plastic caulking with a roll. (A) shows the structure after T6 treatment, and (b) shows the structure after solution treatment. .

[FIG. 6] A diagram showing test results of micro hardness (micro Vickers hardness) of powder.

[Fig.7] Micrograph of the extruded material by optical microscope. (A) is T6 heat treatment AZ9

The structure photograph when 1D powder is used, (b) shows the structure photograph when solution-treated AZ9 ID powder is used.

[Fig. 8] A structural photograph in the extrusion direction of an Mg alloy obtained by extruding and solidifying a powder that has been plasticized with a roll 3, 10, 20, 30 times.

FIG. 9 is a pole figure of the result of evaluating the orientation of the bottom surface of magnesium.

BEST MODE FOR CARRYING OUT THE INVENTION

[0025] Embodiments and effects of the present invention will be described below.

[0026] The present invention has been made to solve the above-described conventional problems, and a magnesium alloy powder in which fine intermetallic compounds are precipitated and dispersed in a substrate by heat treatment is used as a starting material powder. By passing this between a pair of rolls and applying plastic working to compress and / or shear deform, a coarse Mg alloy powder with a fine structure is produced, and this is compacted and extruded. It is intended to provide a Mg alloy having a high tensile strength exceeding 250 to 350 MPa and a method for producing the same. [0027] (1) Starting material powder and production method thereof

Mg as the main component, and other elements that form intermetallic compounds such as Al, Mn, Zn, Re (rare earth elements), Ca, Si, strontium (Sr), zirconium (Zr), scandium (Sc) and An Mg alloy ingot to which an active metal element selected from the group consisting of titanium (Ti) is added is produced by a forging method. By subjecting this Mg alloy ingot to a known T6 heat treatment (solution heat treatment + aging heat treatment), fine intermetallic compounds produced by each additive element are precipitated and dispersed in the substrate. Precipitation · Dispersing intermetallic compound is, for example, Mg

1

Al, Al Ca, Mg Si, MgZn, Al Re (Re: rare earth elements), Al Re, Al Mn, etc.

7 12 2 2 2 3 11 3 6 Since these intermetallic compounds are evenly dispersed in the base material of the Mg alloy after extrusion, it contributes to the improvement of the proof stress. Active metal elements such as strontium (Sr), zirconium (Zr), scandium (Sc) and titanium (Ti) are 0.5 on a weight basis. / ₀ or more 4. By containing less than / _0, the strength can be further increased.

[0028] The heat treatment conditions vary depending on the type of element to be added and the amount of the element to be added. Therefore, it is necessary to set appropriate conditions by observing the structure or measuring the hardness (age hardening curve). Next, a powder having a size of about 0.1 to 10 mm is collected from an Mg alloy ingot by mechanical cutting such as milling, and this is used as the starting material powder of the present invention. In addition, if the particle size of the powder is less than 0.1 mm, it tends to ignite, so from the viewpoint of safety, use a cutting powder of 0.1 mm or more, more preferably 0.5 mm or more.

[0029] (2) Magnesium alloy powder raw material and production method thereof

The Mg alloy powder that has been subjected to the above T6 heat treatment is used as the starting raw material powder, and this is put into the single compactor device shown in Fig. 1.

A roller compactor device shown in FIG. 1 includes a case 11, a multistage roll rotating body 12 disposed in the case 11, a crushing device 13, a powder temperature / supply amount control system 14, and a cradle 15 and. The multi-stage roll rotating body 12 constitutes a plastic working part that performs plastic working on the starting raw material powder, and has three pairs of rolls 12a, 12b, and 12c that perform rolling. The starting material powder undergoes compression deformation and / or shear deformation when passing between the pair of rolls.

[0031] The starting raw material powder has a predetermined temperature and a predetermined The amount is adjusted and put into Case 11. Here, the predetermined temperature is equal to or lower than the temperature of the aging heat treatment described later. The inside of the case 11 is kept in an inert gas atmosphere, a non-oxidizing gas atmosphere, or a vacuum atmosphere from the viewpoint of preventing oxidation of the powder surface. Further, the surface temperature of the multistage roll rotating body 12 and the atmospheric temperature in the case 11 are equal to or lower than the temperature of aging heat treatment described later.

[0032] The powder delivered from the roll pair 12c is subsequently crushed by the crushing device 13 into a granular powder. The granular powder may be returned to the powder temperature / supply amount control system 14 again, and the plastic check by the multistage roll rotating body 12 may be repeated. The processed granular powder is stored in the cradle 15.

[0033] The following structure control is performed by applying a plastic calorie in which the powder is passed between a pair of rolls to compress and / or shear.

(A) As shown in FIG. 2, more work strain 22 is imparted around the intermetallic compound particles 21 precipitated and dispersed in the base of the magnesium alloy powder 20. This processing strain 22 is twin crystal dislocations introduced and accumulated around the intermetallic compound particles 21 due to plastic processing, and looks streak when observed with a transmission electron microscope (TEM).

[0035] (b) The maximum size of the powder after plastic processing is 10 mm or less, and the minimum size of the powder is 0.1 mm or more.

[0036] (c) The starting material powder is relatively smaller than the crystal grain size of magnesium.

[0037] (d) The maximum crystal grain size of the magnesium particles constituting the powder base is 20 _β m or less.

[0038] If necessary, the Mg alloy powder raw material that has been subjected to the plastic casing by the roll is subjected to crushing-pulverization 'sizing treatment, and then plastic processing by the roll is performed again under the same conditions. By repeating the process, an Mg alloy powder raw material having the microstructure defined by the present invention is created.

[0039] First, with regard to (a), when a plastic casing is performed by passing the powder between rolls, processing strain is imparted to the entire powder, but intermetallic compound particles are precipitated and dispersed in the substrate. As a result, more processing strain is applied to the periphery of the intermetallic compound particles than the substrate. So this By repeating plastic processing, more processing strain accumulates around the intermetallic compound particles. When the processing strain increases, the inventors of the present application generate more nucleation sites for dynamic recrystallization that occurs during the extrusion process, which is a subsequent process, and the finer finer particles that could not be realized by conventional Mg alloy manufacturing methods. It was found that crystal grains can be formed.

[0040] Regarding this new knowledge, there is a similar description in JP-A-5-306404. In other words, a method of producing a Mg alloy member by extruding the compact after compacting the Mg alloy powder collected by cutting from an A1-containing Mg alloy member that has undergone T6 treatment with a hot press Has proposed. However, in the manufacturing method disclosed here, the strong plastic case as proposed in the present invention is forcibly applied to the cutting Mg alloy powder treated with T6. As a result, fine crystal grains that cannot form the nucleation sites for dynamic recrystallization as described above cannot be obtained. For example, the tensile strength of the Mg alloy when using the AZ80 alloy cutting powder subjected to T6 heat treatment is as low as about 200 MPa. Further, as described above, the tensile strength of the extruded material when using AZ80 powder not subjected to T6 heat treatment is 200 MPa, which is not much different from that during T6 heat treatment. This is fundamentally different from the manufacturing method in which processing strain is preferentially accumulated around dispersed particles and used as a nucleation site for dynamic recrystallization.

[0041] Further, in the present invention, processing strain is imparted in a random (disordered) direction by repeatedly performing a plastic cage with a pair of rolls on the powder. As a result, the crystal orientation is disordered in the Mg alloy after extrusion and the elongation is improved. In other words, in ordinary extruded materials, the force S that reduces the elongation when the (0001) bottom surface, which is the sliding surface of Mg, is arranged along the extrusion direction, and the plastic working by the pair of rolls of the present invention. When extruding the applied Mg alloy powder, in addition to the (0001) bottom surface, non-bottom surfaces such as (10-10) column surfaces and (10-11) conical surfaces are arranged along the extrusion direction. As a result, it is possible to create an Mg alloy having high elongation in addition to high resistance.

[0042] On the contrary, when the Mg alloy powder not subjected to the T6 heat treatment is subjected to the same plastic case by the roller compactor device, the refinement of the magnesium crystal grains is confirmed, but the T6 heat treatment is performed. As a result, fine crystals as in the case were not obtained. Therefore, used in the present invention In order to make grain refinement more effective by plastic molding using a pair of rolls, it is necessary to deposit and disperse intermetallic compound particles in the base material of the Mg alloy powder raw material. .

[0043] The size of the intermetallic compound particles has a strong correlation with the amount of processing strain accumulated around the particles. The smaller the particle size of the intermetallic compound, the more processing strain can be accumulated, and as a result, an Mg alloy having high resistance to mosquitoes can be obtained. Specifically, by setting the maximum particle size of the intermetallic compound that precipitates and disperses on the raw material powder base to 5 am or less, an Mg alloy having high resistance exceeding 250 MPa can be obtained. If the maximum particle size of the intermetallic compound is 2 μm or less, more processing strain can be accumulated with less plastic cage. As a result, a high yield strength can be obtained, and an Mg alloy having fine crystal grains and high strength resistance can be produced under a condition in which the number of plastic rolls in a pair of rolls is reduced. The economic effect is also obtained.

[0044] Therefore, a manufacturing method was developed when the Mg alloy powder in which fine intermetallic compound particles by T6 heat treatment were preliminarily precipitated and dispersed in the substrate was passed through a pair of rolls and plastically processed. This is a feature for realizing a Mg alloy that has both high yield strength and high toughness with fine crystal grains in Ming.

[0045] Next, regarding (b), the maximum size of the Mg alloy powder after plastic processing with a pair of rolls is set to 10 mm or less, and the minimum size of the powder is set to 0.1 mm or more. If the maximum size of the powder exceeds 10 mm, the bonding between the powders will be reduced during the compacting of the powder, which is the next process, or the corners of the mold will be filled when placed in the mold. As a result, there is a problem in that a chipping occurs at the end of the green compact after molding. On the other hand, when the minimum size of the Mg alloy powder is less than 0.1 mm, it tends to ignite, which causes a safety problem in handling.

[0046] With regard to (c) and (d), by carrying out a plastic casing with a pair of rolls, Mg having a relatively small size and crystal grains relative to the crystal grain diameter of magnesium of the starting raw material powder Make alloy powder. Specifically, in the Mg alloy powder after plastic working with a pair of rolls, the maximum crystal grain size of the magnesium particles constituting the substrate is set to 20 xm or less. By compacting and extruding such an Mg alloy powder, an Mg alloy having a resistance to over 250 MPa can be obtained. Conversely, the magnesium particles of the powder after plastic casting with a roll When the crystal grain size exceeds 20 μm, it is difficult to obtain high resistance exceeding 250 MPa with Mg alloy prepared using such Mg alloy powder. In order to obtain even higher resistance to Mg alloys, for example, characteristics exceeding 350 MPa, the base crystal grain size of the Mg alloy powder after plastic casting with a pair of rolls should be 10 μm or less. There is a need to.

[0047] In the plastic cage using a roll, the temperature of the starting raw material powder to be charged and the surface temperature of the roll in contact with the powder must be equal to or lower than the aging heat treatment temperature in the subsequent step. When plastic working is performed at a temperature higher than the aging heat treatment temperature, the amount of working strain accumulated around the intermetallic compound particles decreases due to the overaging phenomenon, and the dynamic recrystallization during the extrusion process effectively proceeds. As a result, it is difficult to obtain a high strength Mg alloy having fine crystal grains.

[0048] (3) Magnesium alloy and method for producing the same

The magnesium alloy powder raw material subjected to the above-described plastic molding by the roll is compacted and warm-extruded to obtain a high strength Mg alloy having the following characteristics.

[0049] (a) The maximum crystal grain size of magnesium particles constituting the base of the obtained Mg alloy is 10 μm or less C.

[0050] (b) The alloy has a tensile strength at room temperature of S250 MPa or more.

[0051] The inventors of the present application, in particular, in the case of using a raw material having a magnesium alloy crystal grain size of 10 / m or less in the base of the Mg alloy powder, It was found that the maximum crystal grain size constituting the substrate was 5 / m or less, and the tensile strength of the alloy at room temperature was 350 MPa or more. In addition, Mg Al, Al Ca, Mg Si, MgZn, Al Re (Re: rare earth element), Al Re, Al Mn dispersed in the base material of T6 treated input material

17 12 2 2 2 3 11 3 6 and other intermetallic compounds also improve the resistance of Mg alloys after extrusion.

[0052] The above-mentioned magnesium alloy powder raw material that has been subjected to plastic covering with a roll is pressed in a state of being filled in a mold to produce a green compact. The compact is heated in the temperature range of 150 ° C to 450 ° C, and then immediately solidified by extrusion to produce a magnesium alloy material. If the heating temperature is less than 150 ° C, dynamic recrystallization does not proceed and fine magnesium crystal grains cannot be obtained. On the other hand, if the heating temperature exceeds 450 ° C, it will be fine. There is a problem that the recrystallization structure grows and becomes coarse. In consideration of the effect of heat generated during extrusion, the molded body temperature is preferably 200 ° C to 350 ° C. From the viewpoint of densification, the extrusion ratio is 10 or more, more preferably 30 or more.

Example 1

[0053] An AZ91D ingot (composition _A1: 9.1, Zn: 0.85, Mn: 0.23 wt%, Mg: balance) prepared by a forging method was subjected to a solution heat treatment (413 ° CX for 16 hours after heating) After air cooling, an aging heat treatment (251 ° C. X 4 hours after heating and cooling in a nitrogen gas furnace) was performed. Powder was produced from this ingot by pulverization (T6 heat-treated AZ91D powder).

[0054] On the other hand, as a comparison, a powder was produced by pulverization under the same conditions in a state where the fabricated ingot was only subjected to solution heat treatment (solution treatment AZ91D powder). The particle size of the powders of la and misalignment was in the range of 0.5 mm to 4 mm.

[0055] Each AZ91D powder was used as a starting material, and was subjected to plastic caloe using a roller compactor device. Here, the roll diameter was 100 mm, the peripheral speed of the roll was 100 mm / second, the clearance between the rolls was 0.1 mm, and the surface temperature of the roll and the raw material powder temperature were both normal temperatures. Predetermined magnesium alloy powder (one-pass product) was prepared by pulverizing the plate-like connected powders, which were plastic-carried by rolls, to a length of about 5 mm to 5 mm using a cutter mill device. By repeating this process, the crystal grains were refined. Here, the powders after 20 and 40 repetitions are N = 20 and 40, respectively, and N = 0 when no plastic force due to the roll is applied.

[0056] Fig. 3 is a structure photograph of AZ91D ingot, (a) is a structure photograph after fabrication, (b) is a structure photograph after solution treatment, (c) is after T6 heat treatment (solution + aging heat treatment) Show your organization picture. As is clear from the structural photograph in Fig. 3, the solution treatment causes the coarse Mg A1 compound that has precipitated after forging to form a solid solution in the magnesium substrate.

17 12

It is recognized that fine intermetallic compounds are uniformly dispersed in the substrate.

[0057] Fig. 4 shows an enlarged structure photograph of AZ91D after T6 heat treatment in Fig. 3 (c). 500-800 nanometers (nm) of fine granular compounds are uniformly dispersed, and T6 heat treatment As a result, the predetermined tissue structure that is the object of the present invention is formed in the starting material.

[0058] FIG. 5 shows an organizational photograph of the AZ91D powder that has been subjected to plastic covering by a roll. (A) shows the structure after T6 treatment according to the present invention, and (b) shows the structure in the case of only the solution treatment of the comparative example. In the case of using AZ91D powder with T6 treatment, the magnesium substrate shows a homogeneous structure with 20 and 40 plastic rolls, and the grain size is 2-5 microns. It is recognized that it is miniaturized to the extent. On the other hand, when using the AZ91D powder that has undergone the solution treatment of (b), the substrate is heterogeneous even after 40 plastic cycles (white and black areas are mixed in the photo). The magnesium substrate is composed of coarse grain strength exceeding 20 microns.

[0059] Fig. 6 shows the microhardness (micro Vickers hardness) test results of each powder. In any starting raw material powder, the hardness increases with an increase in the number of plastic cages by the roll, but the hardness of the AZ91D powder subjected to T6 heat treatment shows a higher value. Moreover, the difference in hardness between the two increases as the number of machining operations increases. In other words, it can be seen that the AZ91D powder that has undergone T6 heat treatment accumulates more effectively in the substrate than the processing strain force caused by the plastic cage using the direction roll.

Example 2

[0060] Each AZ91D powder produced in Example 1 was molded at room temperature using a hydraulic press to produce a cylindrical extrusion billet. The billet was heated in a nitrogen gas atmosphere at 400 ° C for 5 minutes, and then immediately subjected to warm extrusion (extrusion ratio r = 37) to produce a dense bar. Bow I Zhang specimens from each magnesium alloy extruded material (the parallel portion 20 mm) were collected and subjected to a tensile test at a strain rate per second 10_ ⁴ at room temperature. Table 1 shows the measurement results of tensile strength (0.2% strain), tensile strength, and elongation at break.

[0061] [Table 1] Tensile resistance resistance N 0 20 40

(MPa) T6 heat treatment 210 264 322

Solution treatment 203 229 246

Tensile strength Number of passes N 0 20 40

(M Pa) T6 heat treatment 332 369 385

Solution treatment 327 341 354

Elongation at break Number of passes N 0 20 40

(%) T6 heat treatment 21.2 18.4 18.7

Solution treatment 18.5 14.1 13.2

[0062] By using the AZ91D powder subjected to T6 treatment, which is an example of the present invention, the tensile strength and 0.2% resistance of the extruded material that passed through plastic working by Ronole both increased remarkably. In particular, the tensile strength was high, exceeding 250 to 300 MPa. In addition, the elongation at break remains high at around 18%. Thus, by using the production method according to the present invention, it is possible to produce a magnesium alloy having high tensile strength, high resistance and toughness.

[0063] On the other hand, in the case of using the AZ91D powder, which is a solution heat treatment only, which is a comparative example, the tensile strength and tensile strength increase as the number of rolls of plastic by roll increases. Compared with the results of the T6 heat-treated powder of the present invention example, those values are low, and in particular, the tensile strength reaches 250 MPa.

[0064] Fig. 7 shows the results of tissue observation of the extruded material when the roll was plastic-cured 40 times using an optical microscope. As shown in (a), when the T6 heat-treated AZ91D powder of the present invention example was used, the crystal grain size distribution of the magnesium substrate was measured by image analysis. As a result, the maximum crystal grain size was 4.2 μπι, the average crystal The particle size was 1.5 μπι, and a fine texture was formed by dynamic recrystallization during the extrusion process. On the other hand, when the solution-treated AZ91D powder, which is a comparative example of (b), was used, the maximum crystal grain size of the extruded material was 21 μΐη, and the average crystal grain size was 9.6 μΐη. Compared to the case of the T6 heat treatment AZ9 ID powder shown, the structure is extremely coarse. In other words, when T6 heat-treated Mg alloy powder of the present invention is subjected to plastic working with a roll, more applied strain is generated around fine intermetallic compound precipitates deposited and dispersed on the substrate. As a result, dynamic recrystallization promoted more effectively and formed fine crystal grains.

Example 3 [0065] ZAXE1713 ingot produced by forging method (composition— Α1: 7 · 1, Zn: 0.95, Ca: 0.

93, La: 2. 87 wt%, Mg: the balance) is solution heat treated (air-cooled after heating at 420 ° CX for 16 hours), followed by aging heat treatment (180 ° CX after heating for 36 hours) (Cooled in a furnace with nitrogen gas atmosphere). Powder was produced from this ingot by pulverization (T6 heat-treated ZAXE1713 powder). On the other hand, for comparison, a powder was produced by pulverization under the same conditions without heat-treating the fabricated ingot (ZAXE1713 powder without heat treatment). The particle sizes of the powders of the les and slips were in the range of 0.6 to 4 mm. Each ZAXE1713 powder was used as a starting material and subjected to plastic cleaning using a roller compactor device.

[0066] Here, as in Example 1, the roll diameter was 100 mm, the roll peripheral speed was 100 mm / second, the clearance between the rolls was 0.1 mm, and the roll surface temperature and raw material powder temperature were both normal. did. Predetermined magnesium alloy powder (one-pass product) was prepared by crushing the plate-like connected powder that had been subjected to plastic casing by a roll to a length of about 5 mm to 5 mm with a cutter mill device. By repeating this, the crystal grains were refined. Here, the maximum number of repetitions of plastic working by means of a tool is set to 30 times, and N = 0 when no plastic working by rolls is performed.

[0067] Each ZAXE1713 powder was die-molded at room temperature using a hydraulic press to produce a cylindrical extrusion billet. The billet was heated in a nitrogen gas atmosphere at 400 ° C. for 5 minutes, and immediately subjected to warm extrusion (extrusion ratio r = 37) to produce a dense bar. Tensile specimen from each magnesium alloy extruded material (the parallel portion 20 mm) were collected and subjected to tensile test at room temperature Nitehi Zumi rate per 5 X 10- ^4. Table 2 shows the measurement results of tensile strength (0.2% strain), tensile strength, and elongation at break.

[0068] [Table 2]

[0069] By using the ZAXE1713 powder that has been subjected to the T6 treatment, which is an example of the present invention, Both the tensile strength and 0.2% resistance of the extruded material that passed through the tempering process increased remarkably, and in particular, the tensile resistance showed a high value exceeding 250 to 300 MPa. Also, the elongation at break remains at a high value of over 16%. Thus, by using the production method according to the present invention, it is possible to produce a magnesium alloy having high tensile strength, high resistance and toughness.

[0070] On the other hand, when ZAXE1713 powder that is not heat-treated, which is a comparative example, was used, the tensile strength increased as the number of plastic cages by the roll increased. Compared with the results for the bright T6 heat treated powder, these values are low, and in particular, the tensile strength does not reach 250 MPa.

[0071] With regard to the ZAXE1713 powder that has been subjected to T6 heat treatment, the results of observation of the texture in the extrusion direction of the Mg alloy obtained by extruding and solidifying the powder subjected to plastic processing by rolls 3, 10, 20, 30 times Figure 8 shows. As the number of processing increases, the crystal grain size of magnesium constituting the substrate becomes smaller.In particular, the maximum crystal grain size is 9.2 μΐη and the average crystal grain size is 4.8 μm at 20 times. At 30 times, the maximum crystal grain size was 4.4 μΐη, and the average crystal grain size was 1.2 / im. Example 4

[0072] AZ80A ingot (composition _A1: 8.2, Zn: 0.51%, Mn: 0.18 wt%, Mg: balance) prepared by the forging method was subjected to solution heat treatment (410 ° CX after heating for 6 hours) After air cooling, aging heat treatment (175 ° C × 26 hours after heating and cooling in a nitrogen gas furnace) was performed. Powder was prepared from this ingot by pulverization (T6 heat treatment AZ80A powder). On the other hand, as a comparison, a powder was produced by pulverization under the same conditions without heat treatment of the fabricated ingot (AZ80A powder without heat treatment). All powders had a particle size in the range of 0.6 to 4 mm.

[0073] Each AZ80A powder was used as a starting material, and was subjected to plastic caloe using a roller compactor device. Here, as in Example 1, the roll diameter was 100 mm, the roll peripheral speed was 100 mm / sec, the clearance between rolls was 0.1 mm, and the roll surface temperature and raw material powder temperature were both room temperature. Predetermined magnesium alloy powder (one-pass product) was prepared by pulverizing plate-like connected powder that had undergone plastic working with a roll to a length of about 1 to 5 mm using a cutter mill. By repeating this, the crystal grains were refined. This Here, the maximum number of repetitions of plastic cage by rolls is 50, and N = 0 when no plastic carriage by rolls is applied.

[0074] Each AZ80A powder was molded at room temperature using a hydraulic press to produce a cylindrical extrusion billet. The billet was heated in a nitrogen gas atmosphere at 400 ° C. for 5 minutes and immediately subjected to warm extrusion (extrusion ratio r = 37) to produce a dense bar. Tensile from each Ma Guneshiumu alloy extruded material specimen (parallel part 20 mm) were collected and subjected to tensile test at a rate per second 5 X 10- ⁴ strain at room temperature. Table 3 shows the measurement results of tensile strength (0.2% strain), tensile strength, and elongation at break.

[0075] [Table 3]

[0076] When the AZ80A powder subjected to T6 treatment, which is an example of the present invention, is subjected to plastic working with a roll, the tensile strength is 262 to 317 MPa, which is high at 17 · 9-18.9% Has breaking elongation.

[0077] On the other hand, in the comparative example, even when T6 heat treatment AZ80A powder was used, the tensile strength was as low as 208 MPa unless plastic processing was performed by rolls. In the case of the AZ80A powder without heat treatment, the tensile strength is 218 MPa even when plastic processing with a roll is performed 20 times, which is significantly lower than the example of the present invention.

Example 5

[0078] Using the T6 heat-treated ZAXE1713 powder (number of times of plastic working by roll: 30 times) produced in Example 3, an extrusion billet was produced by molding. When this was densified and solidified by warm extrusion (extrusion ratio r = 37), the billet heating temperature was set as shown in Table 4 to produce a magnesium alloy extruded material. Tensile from each magnesium alloy extruded material specimen (parallel part 20 mm) were collected and subjected to tensile test at a strain rate per second 5 X 10- ⁴ at room temperature. So Table 4 shows the measurement results of tensile strength (0.2% strain), tensile strength, and elongation at break.

[0079] [Table 4]

[0080] When the proper billet temperature specified by the present invention is satisfied, the tensile strength is a high value exceeding 300 MPa. On the other hand, when the billet temperature, which is a comparative example, is 130 ° C, recrystallization during the extrusion process does not proceed sufficiently, so a high bow [cannot obtain tension resistance]. In addition, when the billet temperature is 480 ° C, which is a comparative example, a fine recrystallization structure grows and coarsens during the extrusion process, so high tensile strength cannot be obtained.

Example 6

[0081] Using the T6 heat-treated ZAXE1713 powder produced in Example 3, the plastic structure was rolled up to 30 times under the same conditions as in Example 1 to refine the powder texture structure. . At that time, the temperature of the roll surface and the powder was set to room temperature or 200 ° C. The obtained Mg alloy powder was molded with a hydraulic press at room temperature to produce a cylindrical billet for extrusion. The billet was heated in a nitrogen gas atmosphere at 400 ° C. for 5 minutes, and then immediately subjected to warm extrusion (extrusion ratio r = 37) to produce a dense bar. Tensile from each magnesium alloy extruded material specimen (parallel part 20 mm) were collected and subjected to tensile test at a strain rate per second 5 X 10- ⁴ at room temperature. Table 5 shows the measurement results of tensile strength (0.2% strain), tensile strength, and elongation at break.

[0082] [Table 5]

In the example of the present invention, when the temperature of the roll surface and the powder is normal temperature, the obtained Mg composite The tensile strength and tensile strength of the extruded gold material were V and the deviation was high.

[0084] On the other hand, when the temperature of the roll surface and powder, which is a comparative example, is higher than the aging treatment temperature (175 ° C) and 200 ° C, the tensile strength and tensile strength are both This was significantly lower than that of the inventive example. In particular, the resistance was almost constant despite the increase in the number of machining operations. This is because when Mg alloy powder is heated to a temperature higher than the aging treatment temperature and rolls are subjected to plastic caching, the work strain does not accumulate sufficiently around the precipitates due to the overaging phenomenon. This is because it is difficult to form a fine structure due to dynamic recrystallization in the processing process, resulting in a decrease in yield strength.

Example 7

[0085] The results of evaluating the orientation of the bottom surface (0001) of magnesium with respect to the cross section in the extrusion direction of the AZ80A extruded material produced in Example 4 are shown in the pole figure of FIG. Here, the number of times of plastic working by roll was set to 5, 10, 30, 50 times. Up to 10 processing times, the (0001) plane forms the aggregate texture shown by typical extruded materials along the extrusion direction. However, at 30 and 50 times, the bottom surface orientation is weakened. In other words, non-bottom surfaces such as (10-10) pillar surfaces and (10-11) conical surfaces other than the (0001) bottom surface are aligned along the extrusion direction. I'm doing IJ.

[0086] On the other hand, in the Mg alloy powder not subjected to the heat treatment, the bottom orientation was not significantly decreased even after 50 plastic moldings.

[0087] From the above results, the Mg alloy material obtained by extruding the T6 heat treated Mg alloy powder after applying the plastic casing using the roll specified by the present invention to the dynamic recycle is shown in FIG. In addition to the increase in tensile strength due to the refinement of crystal grains, the fracture elongation (toughness) is improved due to disorder of the texture.

Example 8

[0088] A forged magnesium ingot having the composition shown in Table 6 was subjected to a solution heat treatment (420 ° CX, air-cooled after holding for 16 hours), followed by an aging heat treatment (180 ° CX, 36 hours after holding for 36 hours). Cooling in a furnace in a gas atmosphere.

[0089] [Table 6] Kanari (wt%)

Sample No. Number of machining Zn Al Ca and a 2r Sr Sc Ti Mg

1 30 0.95 7.1 1 0.93 2.87 0 0 0 0 balance

2 30 1.06 6.94 0.98 3.04 0.85 0 0 0 Balance

3 30 1.1 1 7.15 1.08 2.93 1.97 0 0 0 balance

4 30 0.99 6.98 1.11 2.89 0 1.93 0 0 balance

5 30 1.03 7.09 0.97 2.97 0 2.59 0 0 balance

6 30 0.99 6.84 0.95 3.06 0 0 0.89 0 balance

7 30 1.05 7.01 1.02 2.98 0 0 0 1.16 balance

8 30 1.06 7.07 0.98 2.95 0 0 0 2.07

9 30 0.96 7.08 1.1 1 2.87 0 1.03 0 0.86 balance

10 0 0.95 7.1 1 0.93 2.87 0 0 0 0 balance

1 1 0 1.1 1 7.15 1.08 2.93 1.97 0 0 0 balance

12 0 1.03 7.09 0.97 2.97 0 2.59 0 0 balance

[0090] A magnesium alloy powder was produced from each ingot by pulverization. All powders had a particle size in the range of 0.6 to 4 mm. Each powder was used as a starting material, and a plastic cage was applied using a roller compactor. Here, as in Example 1, the roll diameter was 100 mm, the roll peripheral speed was lOO mmZ seconds, the clearance between the rolls was 0.1 mm, the roll surface temperature and the raw material powder temperature were low, and the deviation was normal temperature.

[0091] Predetermined magnesium alloy powder (one-pass product) was produced by pulverizing the plate-like connected powder subjected to plastic working with a roll to a length of about 5 mm to 5 mm with a cutter mill device. By repeating this, the crystal grains were refined. Here, the number of repetitions of the plastic force due to Ronole was 30. As a comparison, N = 0 is the case where plastic rolls are not applied.

[0092] Subsequently, each processed powder was molded at room temperature using a hydraulic press to produce a cylindrical extrusion billet. The billet was heated in a nitrogen gas atmosphere at 400 ° C. for 5 minutes and immediately subjected to warm extrusion (extrusion ratio r = 37) to produce a dense bar. Tensile specimen from each magnesium alloy extruded material (the parallel portion 20 mm) were collected and subjected to tensile test at room temperature Nitehizu seen rate per 5 X 10- ^4. Table 7 shows the measurement results of tensile strength (0.2% strain), tensile strength, and elongation at break.

[0093] [Table 7]

[0094] Sample Nos .:! To 9 are examples of the present invention, and Samples Nos. 2 to 9 are forged magnesium alloys in which an active metal element such as Zr, Sr, Sc, and Ti is added to Sample No. 1 in an appropriate range. It is an extruded material obtained using powder collected from an ingot. Compared to the characteristics of sample No. 1, the addition of active metal elements such as Zr, Sr, Sc, Ti improves the tensile strength and tensile strength without significantly reducing elongation (toughness). be able to.

[0095] On the other hand, in Sample Nos. 10 to 12, which are comparative examples, if plastic working with a roll is not performed, even if an active metal element is added, § I tension resistance against tensile strength increases. Not recognized, the decrease in elongation occurred.

Although the embodiments of the present invention have been described above with reference to the drawings, the present invention is not limited to the illustrated embodiments. Various modifications and variations can be made to the illustrated embodiment within the same range or equivalent range as the present invention.

Industrial applicability

The present invention can be advantageously used to obtain a magnesium alloy that achieves both high yield strength and elongation.

Claims

The scope of the claims

[1] A starting material powder having a relatively large crystal grain size is subjected to plastic working that is compressed or sheared through a pair of rolls to obtain a relatively small crystal grain size. Alloy powder raw material,

The starting material powder is a magnesium alloy powder obtained by precipitating and dispersing fine intermetallic compounds in the substrate by heat treatment.

In the magnesium alloy powder after the plastic working, there is a working strain around the precipitated intermetallic compound,

The maximum size of the magnesium alloy powder after the plastic working is 10 mm or less, and the minimum size is 0.1 mm or more,

A magnesium alloy powder raw material characterized in that the maximum crystal grain size of magnesium particles constituting the base of the magnesium alloy powder after the plastic working is 20 µm or less.

[2] The intermetallic compound is Mg Al, Al Ca, Mg Si, MgZn, Al Re (Re: rare earth element)

17 12 2 2 2 3

Element), at least one compound selected from the group consisting of Al Re and Al Mn,

11 3 6

The magnesium alloy powder raw material according to claim 1.

[3] The magnesium alloy powder raw material according to claim 1, wherein the maximum particle size of the intermetallic compound is 5 μm or less.

[4] The magnesium alloy powder raw material according to claim 1, wherein the maximum particle size of the intermetallic compound is 2 μm or less.

[5] The magnesium alloy powder raw material according to claim 1, which has a maximum crystal grain size force S10 of 0 μm or less of the magnesium particles constituting the base of the magnesium alloy powder.

[6] Containing 0.5% to 4% by weight of a metal element selected from the group consisting of strontium (Sr), zirconium (Zr), scandium (Sc) and titanium (Ti), with the balance substantially The method for producing a magnesium alloy powder raw material according to claim 1, wherein the magnesium alloy is magnesium (Mg).

[7] A magnesium alloy obtained by subjecting the magnesium alloy powder raw material according to claim 1 to compacting and extrusion,

The maximum grain size of the magnesium particles constituting the alloy substrate is 10 μm or less, High-magnesium alloy with a tensile strength at room temperature of 250 MPa or more.

[8] The maximum grain size of the magnesium particles constituting the base of the magnesium alloy is 5 μm or less,

The high-magnesium-resistant alloy according to claim 7, wherein the tensile strength at room temperature is 350 MPa or more.

[9] Mg Al, Al Ca, Mg Si, MgZn, Al Re (Re

17 12 2 2 2 3

: Rare earth element), at least one metal selected from the group consisting of Al Re and Al Mn

11 3 6

The high-magnesium-resistant alloy according to claim 7, wherein the intermetallic compound is precipitated and dispersed.

[10] A method for refining the crystal grain size of the magnesium particles constituting the substrate of the starting material powder by subjecting the starting material powder to plastic working.

As the starting material powder, a magnesium alloy powder is prepared by precipitating and dispersing fine intermetallic compounds in the substrate by heat treatment,

The plastic working is a plastic working in which a starting raw material powder is passed between a pair of rolls and subjected to compression deformation or shear deformation to impart working strain around the intermetallic compound,

The plastic working is repeated until the maximum size of the powder is 10 mm or less, the minimum size is 0.1 mm or more, and the maximum crystal grain size of the magnesium particles constituting the powder base is 20 μm or less. A method for producing a magnesium alloy powder raw material.

[11] The step of preparing magnesium alloy powder as the starting material powder,

Producing a magnesium alloy ingot by a forging method;

Subjecting the magnesium alloy ingot to solution treatment, followed by aging heat treatment to precipitate and disperse fine intermetallic compounds in the base of the ingot;

The method for producing a magnesium alloy powder raw material according to claim 10, comprising: taking out magnesium alloy powder from the ingot by machining.

[12] The temperature of the starting raw material powder to be charged and the surface temperature of the roll in contact with the starting raw material powder when performing the plastic working are set to be equal to or lower than the temperature of the aging heat treatment.

11. A method for producing a magnesium alloy powder raw material according to 11.

[13] The magnesium alloy ingot comprises strontium (Sr), zirconium (Zr), scandi The metal element selected from the group consisting of hum (Sc) and titanium (Ti) is contained in an amount of 0.5% to 4% by weight, with the balance being substantially magnesium (Mg). The manufacturing method of magnesium alloy powder raw material of description.

[14] A step of pressing the magnesium alloy powder raw material according to claim 1 in a state filled in a mold to obtain a green compact,

Heating the magnesium alloy powder compact at a temperature of 150 ° C or higher and 450 ° C or lower;

A process for producing a magnesium alloy by extruding the magnesium alloy compact immediately after the heating, and producing a magnesium alloy.

[15] The production of the high-strength magnesium alloy according to claim 14, wherein the maximum grain size of magnesium particles constituting the base of the magnesium alloy is 10 μm or less, and the tensile strength at room temperature is 250 MPa or more. Method.

16. The method for producing a high-magnesium-resistant alloy according to claim 14, wherein the magnesium alloy powder compact is heated at a temperature of 200 ° C to 350 ° C.