KR101885397B1 - Magnesium alloy material and method for producing the same - Google Patents

Abstract

A magnesium alloy material having a large thickness and excellent press workability, and a process for producing the same. (Mg alloy plate) having a plate-like portion with a thickness of 1.5 mm or more (typically a Mg alloy plate), when a region from the surface of the plate portion to a thickness of 1/4 in the thickness direction is a surface region, , the bottom surface of the inside area peak ratio _(C O), the ratio of [(002) orientation degree of the surface; the bottom surface of the peak surface area ratio _(F O) for: O _F / O _{F C} is 0.95≤O / O _C ? 1.05. The plate-like portion is constituted by a uniform texture throughout the entire thickness direction thereof, so that the plate-like portion is thick and excellent in press workability. By using this alloy material as a material, a press working material excellent in dimensional accuracy can be obtained. The obtained press working material is also constituted by a uniform structure. A plate-like Mg alloy material is obtained by rolling the double-row continuous cast material with one or more rolling at a reduction rate of 25% or more at a reduction rate of 10% or more.

Description

[0001] MAGNESIUM ALLOY MATERIAL AND METHOD FOR PRODUCING THE SAME [0002]

The present invention relates to a magnesium alloy material suitable for various members such as a part of a transportation device such as an automobile or a railway vehicle or an airplane, a bicycle part, a housing of an electronic or electric appliance, other structural members, . In particular, the present invention relates to a magnesium alloy material which is thick and excellent in plastic workability such as press working.

As a constituent material of various members such as a housing of a portable electronic or electric device such as a portable telephone or a notebook type personal computer, an automobile part such as a wheel cover or a paddle shift, a bicycle part such as a railway car part or a frame, , And a magnesium alloy excellent in non-rigidity have been studied. The main component of the magnesium alloy member is casting material (AZ91 alloy of ASTM standard) by the die casting method or thixomolding method. In recent years, a press working material subjected to press working on a plate made of a magnesium alloy for general purpose (represented by AZ31 alloy of ASTM standard) has been continuously used. Patent Document 1 discloses that a continuous casting material made of various magnesium alloys such as AZ91 alloy is manufactured using a double-roll casting method, rolling is performed on the continuous casting material, and press working is performed on the obtained rolled plate.

Patent Document 1: International Publication No. 2006/003899

In view of the light weight of the magnesium alloy, conventionally, a relatively thin plate material having a thickness of 1 mm or less has been studied as a material of a plastic material such as a press processing material. However, with the expansion of the range of applications of the magnesium alloy, it is required to develop a thick plate having a thick thickness, specifically, a thick plate having a thickness of 1.5 mm or more, in consideration of not only the thin plate as described above but also the non-rigidity and non-rigidity. A material such as a magnesium alloy plate having such a thick thickness and excellent plastic workability and a method of manufacturing thereof and a sintering process material such as a press process material produced by using this plate have not been sufficiently studied.

When a die casting method or a thixomold method is used, a thick magnesium alloy sheet can be obtained. However, in a cast material such as a die cast material, internal defects such as pores are present, and the composition of the additive element becomes locally high, or the crystal grains are randomly oriented, and the composition or structure tends to become uneven. Further, in a cast material such as a die cast material, a precipitate is liable to precipitate at grain boundaries. Since the defects and the precipitates of the grain boundaries are the starting point of fracture, the cast material such as the die cast material is inferior in plastic workability such as press working. In addition, mechanical properties such as strength and hardness are lower than those of a plastic material such as a press material due to the internal defects or the like in a cast material such as a die cast material.

Therefore, one of the objects of the present invention is to provide a magnesium alloy material which is thick and excellent in plastic workability, and a magnesium alloy material which is subjected to plastic working and has a large thickness. Another object of the present invention is to provide a method for producing a magnesium alloy material having a thick thickness and excellent in plastic workability.

The magnesium alloy material subjected to the plastic working (primary working) such as rolling compared with the die casting or the thixomolding material has the advantage that even when the defects during casting are reduced or the crystal is made finer, the strength, hardness, Is excellent in mechanical properties, corrosion resistance and plastic workability. In addition, the magnesium alloy material subjected to the above primary working magnesium alloy material subjected to plastic working (secondary working) such as press working is also excellent in mechanical properties and corrosion resistance. Particularly, when a continuous casting material produced by a continuous casting method such as a two-roll casting method is used as a material of the primary working material, the continuous casting material has less segregation or coarse crystal precipitates compared with die casting materials and has excellent plastic workability . Therefore, the inventors of the present invention conducted a continuous casting material under various conditions to prepare a magnesium alloy sheet having a thickness of 1.5 mm or more, and investigated its plastic workability. Here, the rolled material (rolled plate) of a magnesium alloy generally has a texture in which the bottom face of the magnesium alloy is oriented parallel to the rolling direction (the direction in which the rolled material advances). If the degree of integration in the texture is strong, the plasticity is deteriorated at the time of plastic working such as press working. The present inventors have found that (1) the aggregate structure at the surface side portion of the rolled plate has a lower degree of moldability (plastic workability) when the degree of integration is higher than that of the aggregate structure at the inner portion of the rolled plate, (2) Conventional rolling on a thick material to obtain a rolled material having a large thickness results in the texture of the surface portion of the rolled material being developed in comparison with that of the inner portion, Was not obtained. Further, the inventors of the present invention have found that a magnesium alloy sheet produced under a specific condition has a thick thickness and is excellent in plastic workability as in press working. The present invention is based on the above findings.

The magnesium alloy material of the present invention is made of a magnesium alloy and has a plate portion having a thickness of 1.5 mm or more, and the plate portion satisfies the following orientation property.

[Orientation]

A region from the surface of the plate portion to a thickness of 1/4 in the thickness direction is defined as a surface region and the remaining portion is defined as an inner region,

The peak intensities of the (002) plane, (100) plane, (101) plane, (102) plane, (110) plane and (103) plane in the surface region are I _{F F} (100), I _F (101), I _F (102), I _F (110), and I _F (103)

The peak intensities of the (002) plane, the (100) plane, the (101) plane, the (102) plane, the (110) plane and the (103) plane in the inner region are I _{C C} (100), I _C (101), I _C (102), I _C (110), and I _C (103)

The degree of orientation of the plane (002) in the surface _{region: I F (002) / {} I F (100) + I F (002) + I F (101) + I F (102) + I F (110) + I _F (103)} to the bottom surface peak ratio (O _F )

The degree of orientation of the plane (002) in the inner _{region: I C (002) / {} I C (100) + I C (002) + I C (101) + I C (102) + I C (110) + I _C (103)} is the bottom surface peak ratio (O _C )

The ratio O _F / O _C of the bottom surface peak ratio (O _F ) of the surface region to the bottom surface peak ratio (O _C ) of the inner region satisfies 0.095? O _F / O _C ?

The magnesium alloy material of the present invention can be produced, for example, by the following production method of the present invention. A manufacturing method of a magnesium alloy material of the present invention relates to a method of manufacturing a magnesium alloy material by rolling a material made of a magnesium alloy, and comprises the following preparation step and rolling step.

Preparation process: A step of preparing a plate-like material obtained by continuously casting a molten magnesium alloy by a double-roll casting method.

Rolling step: a step of rolling the material through multiple passes to produce a plate-shaped magnesium alloy material having a thickness of 1.5 mm or more.

In this rolling step, rolling is performed at least one pass at a reduction rate of 25% or more per one pass, and the reduction rate of each of the remaining passes is at least 10%.

The reduction rate (%) is defined as {(thickness t _b before rolling, t _a after rolling, t _b ) x 100.

According to the production method of the present invention, it is possible to obtain a relatively low rolling reduction rate per pass of 25% or more by using a continuous cast material having few defects, crystal precipitates, segregation, or substantially no starting points such as cracks It is possible to satisfactorily carry out rolling which is a strong working. Further, in this rolling with a high reduction ratio, plastic working can be uniformly performed over the entire thickness direction of the material. That is, by performing at least one pass of rolling with a high reduction ratio, it is possible to uniformly process the material from the surface to the inside thereof. Therefore, according to the manufacturing method of the present invention, a magnesium alloy material (typically, a rolled plate (one form of the magnesium alloy material of the present invention)) constituted by a uniform structure over the entire thickness direction is obtained. This structure is an aggregate structure (aggregate structure in which the c-axis of the crystal is arranged so as to be orthogonal to the rolling direction) mainly arranged so that the bottom face of the crystal of the magnesium alloy is parallel to the rolling direction.

As described above, when the magnesium alloy material of the present invention is a rolled plate subjected to the above-mentioned specific rolling (that is, when the entire magnesium alloy material of the present invention is constituted by a plate portion) To-surface). The magnesium alloy material of the present invention having such a uniform structure has a thick thickness and is excellent in plastic workability as in press working. Therefore, this plate-shaped magnesium alloy material can be suitably used for a plastic working material such as a press working. Further, the magnesium alloy material has a uniform structure and thus has uniform characteristics (mechanical properties such as hardness, strength, impact resistance, toughness, corrosion resistance, vibration damping property, etc.). In addition, when the above-described plate-shaped magnesium alloy material is used for a plastic working material, a plastic working material (a form of the magnesium alloy material of the present invention) such as a press working material having excellent dimensional accuracy is obtained. The obtained plasticized material also has a uniform structure throughout its thickness direction. That is, the structure of the material is substantially maintained. Therefore, the sintering process material such as the obtained press process material has the above uniform characteristics.

As a magnesium alloy material in the form of the invention, when the average crystal grain size of the surface area, the average crystal grain size of the D _F, the inner region to the D _C, the inside of the average crystal grain diameter (D _F) of the surface area the average crystal grain diameter (D _C) the ratio of the area: D _C / D _F is satisfied a _{2 / 3≤D C / D F ≤3} / 2, can be given in the form D _F D and _C ≥3.5 ㎛.

According to this embodiment, since the uniform particle diameter is distributed throughout the entire thickness direction, it is more excellent in plastic workability.

In one embodiment of the magnesium alloy material of the present invention, when Vickers hardness (Hv) of the surface region is H _F and Vickers hardness (Hv) of the inner region is H _C , the Vickers hardness (H _F ) The ratio of the Vickers hardness (H _C ) of the inner region to the inner region: H _C / H _F satisfies 0.85? H _C / H _F? 1.2.

According to this embodiment, since the magnesium alloy material has a uniform hardness over the entire thickness direction, even if a part of the magnesium alloy material is partially subjected to grinding or chemical treatment to remove the surface side portion, The surface hardness of the subsequent magnesium alloy material does not change substantially before and after the processing or treatment and has a stable surface property. Therefore, according to this embodiment, when the surface treatment such as the chemical treatment is performed in the subsequent step, this treatment can be stably performed.

The magnesium alloy material of the present invention may be composed of a magnesium alloy (remaining Mg and impurities) having various elements as additive elements. Particularly, an alloy having a high concentration of added elements, specifically, a magnesium alloy having a total content of 5.0 mass% or more, has various properties such as mechanical properties such as strength and hardness, corrosion resistance, flame retardancy and heat resistance Excellent in characteristics.

Specific additive elements include at least one element selected from Al, Zn, Mn, Si, Be, Ca, Sr, Y, Cu, Ag, Sn, Li, Zr, Ce, Ni, Au and rare earth elements Species of the species. Examples of the impurities include Fe and the like.

In particular, the Mg-Al-based alloy containing Al is excellent in corrosion resistance and mechanical properties such as strength and hardness. Accordingly, as a form of the magnesium alloy material of the present invention, the magnesium alloy may contain Al in an amount of 5.0 mass% or more and 12 mass% or less in the added element. The higher the content of Al, the higher the effect is, and preferably 7 mass% or more, and more preferably 7.3 mass% or more. However, if the content of Al exceeds 12 mass%, the firing processability is lowered. Therefore, the upper limit is preferably 12 mass% and more preferably 11 mass%. Particularly, the form containing 8.3 mass% to 9.5 mass% of Al is more excellent in strength and corrosion resistance. The content of each element other than Al is 0.01 mass% or more and 10 mass% or less, preferably 0.1 mass% or more and 5 mass% or less in total.

A more specific composition of the Mg-Al-based alloy is, for example, an AZ-based alloy (Mg-Al-Zn-based alloy, Zn: 0.2 to 1.5 mass%, such as AZ31 alloy, AZ61 alloy, AZ91 alloy, etc.) (Mg-Al-Mn alloy, Mn: 0.15 mass% to 0.5 mass%), an AS alloy (Mg-Al-Si alloy, Si: 0.01 mass% to 20 mass% (Mg-Al-Ca alloy, Ca: 0.2 mass% to 6.0 mass%), AJ alloy (Mg-Al-Sr alloy, Sr: 0.2 mass% Mass%), and the like. An Mg-Al-Zn alloy containing 0.5% by mass to 1.5% by mass of Zn, and typically an AZ91 alloy can be given as an alloy containing 8.3% by mass to 9.5% by mass of Al.

In addition, the content of at least one element selected from Y, Ce, Ca, Si, Sn and rare earth elements (excluding Y and Ce) is 0.001 mass% or more in total, preferably 0.1 mass% or more and 5 mass% And the balance of Mg and impurities is excellent in heat resistance and flame retardancy. When the rare earth element is contained, the total content thereof is preferably 0.1 mass% or more, particularly preferably 0.5 mass% or more when Y is contained.

The magnesium alloy material of the present invention is thick and excellent in plastic workability. INDUSTRIAL APPLICABILITY The method for producing a magnesium alloy material of the present invention can produce a magnesium alloy material having a large thickness and excellent in plastic workability.

Hereinafter, the present invention will be described in more detail.

[Magnesium alloy material]

(Furtherance)

The magnesium alloy material of the present invention is constituted by 50 mass% or more of Mg, and typically a magnesium alloy containing the above-described additive elements.

(shape)

The plate-like portion included in the magnesium alloy material of the present invention is a portion provided with a pair of parallel surfaces and having a substantially uniform thickness (distance between both surfaces), that is, a uniform thickness. When the magnesium alloy material of the present invention has a plate-like portion in a part thereof, the magnesium alloy material may be subjected to a cutting process or the like such as a form in which a boss or the like is bonded, a shape having a groove, It is permissible to have shapes with different thicknesses.

A representative form of the magnesium alloy material of the present invention having the plate-like portion is a form (magnesium alloy plate) in which the whole is plate-shaped. The shape (planar shape) of the magnesium alloy plate can take various shapes such as a rectangular shape and a circular shape. Further, the magnesium alloy plate can take any form of a coil material in which a continuous long material is wound, and a short length material having a predetermined length and shape. This magnesium alloy plate can take various forms depending on the manufacturing process. Typically, a rolled plate, a heat-treated plate or a calibrated plate subjected to a heat treatment or calibration described later, a rolled plate or a heat-treated plate, and an abrasive plate or a coated plate subjected to polishing or coating are provided.

In addition, the magnesium alloy material of the present invention can be obtained by molding a magnesium alloy plate subjected to plastic working (secondary working) such as bending or drawing, or the like, a part subjected to the plastic working, (Provided that at least a part thereof has the plate portion). The molded article may be, for example, a top or bottom type frame having a top plate portion and a side wall portion provided upright from a peripheral edge of the top plate portion, a top plate portion having a circular plate shape, And the like. At least the top plate portion corresponds to a plate-like portion. Depending on the intended use, the shape of the magnesium alloy material can be selected.

(thickness)

The magnesium alloy material of the present invention is characterized in that the thickness of the plate-shaped portion is 1.5 mm or more. The thickness can be set to an arbitrary value of 1.5 mm or more in accordance with the intended use or the like. However, in order to thicken the plate-like portion, the casting material to be a material must also be thick. When the casting material is made thick, the rolling property is deteriorated due to defects or the like as described above. Therefore, it is preferable that the thickness is 10 mm or less, particularly 5 mm or less, because a thick rolled plate (a form of the magnesium alloy material of the present invention) can be produced with good productivity.

In the case where the magnesium alloy material of the present invention is the molded article or the partially processed material, a portion (typically, a plate-like portion) having little deformation accompanied by the plastic working can be formed into a structure or mechanical property of the magnesium alloy sheet .

(group)

<Orientation>

The magnesium alloy material of the present invention is characterized in that at least the plate-like portion is constituted by a structure having a uniform texture throughout the entire thickness direction thereof. The form in which the ratio of the above-mentioned bottom face peak ratio O _F / O _C satisfies particularly 1.00? O _F / O _C? 1.05 is more excellent in plastic working property. In addition, the obtained fired workpieces (formed bodies) and partial workpieces have small fluctuations in mechanical properties throughout them.

&Lt; Average crystal grain size &

As a representative form of the magnesium alloy material of the present invention, there can be mentioned a form in which the crystal grain size is uniform over the entire thickness direction as described above. This form can be uniformly deformed when plastic working such as press working is performed, and a plastic working material (molded article) and a partial working material having excellent dimensional accuracy can be obtained. The smaller the surface area and the inner area difference between the average crystal grain size because the expected capable of performing plastic working to even small, the ratio of the aforementioned mean grain size: D _C / D _F is especially 1≤D _C / D _F ≤ 1.4 is more excellent in plastic workability. In addition, the obtained fired workpieces (formed bodies) and partial workpieces have small fluctuations in mechanical properties throughout them.

Further, in the case of producing a magnesium alloy material having a thickness of 1.5 mm or more and a plate-like shape by rolling as described above, it is difficult to obtain a uniform grain size and fine grain size over the entire thickness direction, The minimum value of the crystal grain size is about 3.5 탆. However, since the smaller the crystal grain size tends to be excellent in the plastic workability, the average crystal grain size of the plate-like portion is preferably 20 占 퐉 or less, particularly 10 占 퐉 or less. The average crystal grain size varies depending on the reduction rate in the rolling process and the heating temperature of the material, and tends to decrease as the reduction rate is higher and the heating temperature is lower. In addition, the average crystal grain size of the surface region which tends to be sufficiently subjected to the plastic working during rolling tends to be smaller than that of the inner region.

(Mechanical Properties)

The magnesium alloy material of the present invention is superior in mechanical properties such as strength, hardness and toughness as compared with a cast material such as a die cast material by being rolled and has a uniform mechanical characteristic over its entire thickness direction . For example, as described above, the Vickers hardness is a uniform value. The difference in Vickers hardness is less in the surface region and the inner region mechanically weak (low hardness portion) because not present in the substantial, proportion of the Vickers hardness (Hv): H _C / H _F is 0.95≤H _C / H _F ≤ 1.1 is more preferable. The absolute value of the Vickers hardness tends to increase as the content of the additive element increases, depending on the rolling conditions such as the reduction rate and the heating temperature of the material. In addition, the Vickers hardness of the surface region, which is subjected to sufficient plastic working during rolling, tends to be larger than that of the inner region. When the magnesium alloy material of the present invention is a sintered material (molded article) or a partially processed material, the hardness tends to become higher due to work hardening.

(Other configurations)

When at least a part of the surface of the magnesium alloy material of the present invention is subjected to a treatment such as chemical treatment or anodic oxidation treatment to form a method layer, corrosion resistance is more excellent. Further, if a coating layer is provided on at least a part of the surface of the magnesium alloy material of the present invention, it is possible to enhance the designability and the product value.

[Manufacturing method]

Hereinafter, each step of the production method of the present invention described above will be described in more detail.

(Preparation process)

<Casting>

In the production process of the present invention, a continuous cast material is used as a starting material. The continuous casting method is capable of rapid quenching and solidification. Therefore, even when the content of the additive element is large, it is possible to reduce segregation, oxides and the like, and to suppress generation of coarse crystal precipitates of more than 10 mu m have. Therefore, a cast material having excellent plastic workability such as rolling can be obtained. Further, in the continuous casting method, a long cast material can be continuously produced, and the long material obtained by this continuous casting method can be used as a material for rolling. When the material is long, a long rolled material can be manufactured. There are various methods such as a twin-roll method, a twin-belt method and a belt-and-wheel method for the continuous casting method. The twin-roll method and the twin-belt method, It is preferable to use a continuous cast material produced by a casting method. The thickness, width and length of the cast material can be appropriately selected so as to obtain a desired rolled material (rolled plate). The thickness of the cast material is preferably 10 mm or less, particularly 5 mm or less, since segregation tends to occur if too thick. When the obtained continuous casting material is made into a long material, if it is wound into a cylindrical shape and made into a coil material, it can be easily returned to the next step. When the portion immediately before winding in the cast material is rolled up in a state of being heated to about 100 캜 to 200 캜, the content of the additive element such as the AZ91 alloy is high and the alloy paper which tends to cause cracking tends to bend. Even if the winding diameter is small , And can be wound without generating cracks or the like. A sheet material obtained by cutting the obtained continuous casting material to an appropriate length may be used as a material for rolling. In this case, a rolled material having a predetermined length (rolled plate) is obtained.

<Solution>

If the solution treatment is performed before rolling the cast material, the composition of the cast material can be homogenized or an element such as Al can be sufficiently solidified to increase the toughness. The conditions for the solution treatment include, for example, a heating temperature of 350 DEG C or higher, particularly 380 DEG C or higher and 420 DEG C or lower, and a holding time of 1 hour or more and 40 hours or less. In the case of the Mg-Al based alloy, it is preferable that the holding time is slightly longer as the content of Al is larger. Further, after the lapse of the holding time, in the cooling step from the heating temperature, if the cooling rate is increased (preferably 50 ° C / min or more) using forced cooling such as water cooling or air blast, It is possible to suppress the precipitation of the precipitate.

<Rolling>

The cast material or the solution treatment material is used as a material, and the material is subjected to multiple passes of rolling. It is preferable that at least one pass includes warm rolling or hot rolling in which the material (casting material, solution treatment material, processing material during rolling) is heated to 150 deg. C or higher and 400 deg. C or lower. By heating the material to the above temperature, even when the reduction rate per one pass is increased, cracking or the like hardly occurs in the rolling, and as the temperature is raised, cracking or the like is reduced. And deterioration of the rolling rolls due to heat can be suppressed. Therefore, the heating temperature is preferably 350 DEG C or less, more preferably 300 DEG C or less, particularly preferably 150 DEG C or more and 280 DEG C or less. Not only the material but also the rolling roll may be heated. The heating temperature of the rolling roll may be 100 deg. C to 250 deg.

Particularly, in the production method of the present invention, rolling (hereinafter, this rolling is referred to as steel working rolling) having a reduction ratio of 25% or more per one pass is performed in one pass or multiple passes. It is preferable that the hot rolling or the hot rolling is performed by the hot rolling as described above. The higher the reduction ratio is, the more sufficient plastic working can be carried out from the surface of the material to the inside thereof, and a rolling material of uniform texture is obtained. Therefore, the reduction ratio of the steel working rolling is preferably 30% Can be appropriately selected within a range in which cracking does not occur. If rolling reduction of each pass (hereinafter referred to as ordinary rolling) other than steel working rolling is set to 10% or more, rolling can be uniformly performed over the entire thickness direction of the work. As described above, the higher the reduction ratio of each pass of the ordinary rolling is, the more the plastic working can be performed, so that it can be set to 15% or more and 20% or more per pass. The number of passes and the reduction rate of steel working rolling and general rolling can be appropriately selected in accordance with the total reduction ratio.

Conditions such as the heating temperature of the material, the temperature of the rolling roll, and the reduction rate can be changed for each pass. Therefore, the reduction rates of the respective passes may be the same or different. Further, intermediate heat treatment may be performed between passes. By performing the intermediate heat treatment, the deformation and the residual stress introduced into the work up to this heat treatment can be removed or reduced, and the rolling after this heat treatment can be easily performed. The conditions for the intermediate heat treatment include a heating temperature of 150 to 350 占 폚 (preferably 300 占 폚 or less, more preferably 250 to 280 占 폚) and a holding time of 0.5 to 3 hours. After the rolling, the final heat treatment may be performed under the above conditions. In addition, when the lubricant is suitably used for the rolling, the frictional resistance at the time of rolling can be reduced, the material can be prevented from being sagged, and rolling can be easily performed.

In addition, the edge portion of the cast material prior to rolling may be trimmed so that cracking does not proceed when the edge portion has a crack at the time of rolling. In order to adjust the width appropriately during the rolling process, .

<Other Processing>

«Polishing»

After the rolling, polishing may be performed. By performing the polishing, it is possible to remove and reduce the lubricant used at the time of rolling, scratches and oxide films existing on the surface of the rolled material, and the like. For grinding, it is preferable to use a grinding belt so that even if the material is made long, the grinding can be easily carried out continuously. Further, the abrasive is preferably wet to prevent scattering of the powder.

«Calibration»

Calibration may be performed after the rolling or after the polishing. By performing the calibration, the flatness can be increased, and the plastic working such as press working can be performed with high precision. In the calibration, a roll leveler device in which a plurality of rollers are arranged in a staggered shape can be suitably used. The calibration may be performed, for example, in a state in which the material is heated to 100 ° C to 300 ° C, particularly 150 ° C to 280 ° C (warm calibration).

«Plastic processing»

In the case where the magnesium alloy material of the present invention is a partially processed material having a molded body or a plasticized portion, at least a part of the material subjected to the rolling process (the rolled material, the abrasive and the calibrating material described above) And a sintering step to be carried out. This plastic working is preferably carried out in a temperature range of 200 ° C to 300 ° C because the plastic workability of the material can be enhanced. In addition, heat treatment is performed after the plastic working to remove strain and residual stress introduced by the plastic working, and to improve the mechanical characteristics. The heat treatment conditions include a heating temperature of 100 占 폚 to 300 占 폚 and a heating time of 5 minutes to 60 minutes.

«Surface treatment»

In the case where the magnesium alloy material of the present invention is provided with the corrosion-resistant layer or the coating layer, at least a part of the material subjected to the above-mentioned rolling process or at least a part of the material subjected to the above- And a surface treatment step to be carried out. In addition, at least a part of the material may be subjected to at least one kind of processing selected from hair line processing, diamond cutting processing, shot blasting processing, etching processing and spin cutting processing. By carrying out these surface treatments, it is possible to enhance the corrosion resistance and the mechanical protection function, or to increase the design property, the metal texture and the product value.

Hereinafter, more specific embodiments of the present invention will be described with reference to test examples.

[Test Example]

A magnesium alloy having the following composition was rolled under various conditions to prepare a magnesium alloy sheet having a thickness of 1.5 mm or more and the orientation properties, crystal grain size, and Vickers hardness were examined.

In this test, a magnesium alloy plate composed of a magnesium alloy (Mg-8.9 mass% Al-0.6 mass% Zn) having a composition corresponding to the AZ91 alloy and a magnesium alloy having a composition corresponding to AZ31 alloy (Mg- 3.0 mass% Al- 0.7 mass% Zn) was prepared.

A long casting plate (thickness 4.5 mm (4.50 mm to 4.51 mm) x 320 mm wide) was produced by the double-roll continuous casting method using the magnesium alloy of each composition described above and wound once to produce a casting coil material. Each casting coil material was subjected to a solution treatment at 400 ° C for 24 hours. Rolled in multiple passes under the rolling conditions shown in Table 1 on the material from which the solution-solidified processing coil material was uncoated to obtain a pressure of 2.0 mm (2.00 mm to 2.01 mm) or 1.5 mm (1.50 mm to 1.51 mm) (Magnesium alloy plate) was produced. Each pass was made by warm rolling (heating temperature of the material: 250 ° C to 280 ° C, temperature of the rolling roll: 100 ° C to 250 ° C). The thickness of the casting material, the thickness of the workpiece during rolling, and the thickness of the obtained magnesium alloy plate are all the average values of the thicknesses of three points in total in the widthwise center of the plate material to be measured and 50 mm from both edges in the widthwise direction Respectively.

[Orientation]

Investigated the _F O / O _C: subjected to X-ray diffraction for each magnesium alloy sheet thus obtained, the ratio of the bottom surface of the surface area of the bottom surface of the interior region to the peak ratio (O _C) peak ratio (O _F). The results are shown in Table 2. The bottom surface peak ratio (O _F ) of the surface region is determined by X-ray diffraction with respect to the surface of each magnesium alloy plate, and the bottom surface peak ratio (O _C ) of the interior region is measured from the surface of each magnesium alloy plate in the thickness direction The area (surface area) up to 1/4 of the thickness was chemically removed to expose the interior, and the exposed surface was subjected to X-ray diffraction. Then, the surface of each region (002) and (100) plane, (101) plane, (102) plane, (110) plane and (103) respectively measuring the peak intensity of the plane and, O, using the result of the measurement _F a / O _C was obtained.

A bottom surface peak ratio _{(O F): I F (} 002) / {I F (100) + I F (002) + I F (101) + I F (102) + I F (110) + I F (103 )}

A bottom surface peak ratio _{(O C): I C (} 002) / {I C (100) + I C (002) + I C (101) + I C (102) + I C (110) + I C (103 )}

[Average crystal grain size]

The average crystal grain size (占 퐉) of the inner region and the surface region of each of the obtained magnesium alloy sheets was measured on the basis of the "steel-crystal grain size microscopic test method JIS G 0551 (2005)". In this case, each magnesium alloy plate was taken in a section in the thickness direction (cross section and longitudinal section), each section was observed with an optical microscope (400 times), and the surface area (1 / 3) and the inner area (the remaining area excluding the surface area) (the total number of field of view of each area: 6), and the average crystal grain size per view was obtained. Table 2 shows the average value (D _F ) of the average crystal grain sizes of six fields in total in the surface region and the average value (D _C ) of the average crystal grain sizes in six fields in total. Further, the ratio of the mean grain size (D _C) of the inner region to the average grain diameter (D _F) of the surface area: D _C / D _F also were determined. The results are shown in Table 2.

[Vickers hardness]

The Vickers hardness (Hv) of the inner region and the surface region of each of the obtained magnesium alloy sheets was examined. The Vickers hardness is determined by taking the cross section in the thickness direction (cross section and longitudinal section) of each magnesium alloy plate and measuring the Vickers hardness (H _F ) of the surface area in the same manner as in the measurement of the average crystal grain size, And the Vickers hardness (H _F ) of the inner area was measured by pressing the indentation firmly against the inner area in each of the above-mentioned sections. Table 2 shows the average value (H _F ) of the Vickers hardness of the both end faces in the surface region and the average value ( _{V C} ) of the Vickers hardness of the both end faces in the inner region. Further, the ratio of the Vickers Hardness (H _C) of the inner area of the Vickers hardness (H _F) of the surface area: To also obtain H _C / H _F. The results are shown in Table 2.

As shown in Tables 1 and 2, the continuous cast material is subjected to rolling at least one roll at a reduction ratio of 25% or more per pass and at least 10% It can be understood that a magnesium alloy plate (magnesium alloy material) having a large thickness has a specific orientation and is made of a uniform structure in its thickness direction. In addition, it can be seen that this magnesium alloy plate has uniform mechanical properties.

Each of the obtained magnesium alloy plates was subjected to press working. The press working conditions were the heating temperature of the magnesium alloy plate: 250 占 폚 to 270 占 폚. As a result, it was confirmed that the sample No. 2 having a specific orientation and a uniform structure in its thickness direction was obtained. A, B, D, E, G, H, J and K were excellent in pressability and dimensional accuracy. Also, these sample Nos. The texture of the flat portions in A, B, D, E, G, H, J, and K was examined and found to be substantially the same as the texture of each magnesium alloy plate before press working and had the specific orientation and average grain size.

From the above test results, it was confirmed that the magnesium alloy material having a plate-like portion having a thickness of 1.5 mm or more in thickness, the plate-like portion being composed of a structure having a specific orientation and being made of a uniform structure in its thickness direction, . It was also confirmed that the magnesium alloy material subjected to the press working was constituted of a uniform structure.

It should be noted that the above-described embodiment can appropriately be modified without departing from the gist of the present invention, and is not limited to the above-described configuration. The composition of the magnesium alloy, the thickness and shape of the magnesium alloy material, the reduction rate of each pass in the rolling process, the number of passes, and the like can be appropriately changed.

The magnesium alloy material of the present invention is suitable for members of various fields such as automobile parts, railway vehicle parts, aircraft parts, bicycle parts, parts of various electronic and electric devices, and constituent materials, bags, Can be used. The method for producing the magnesium alloy material of the present invention can be suitably used for producing the magnesium alloy material of the present invention.

Claims (6)

A magnesium alloy material comprising a magnesium alloy and having a plate-like portion,
The thickness of the plate portion is 1.5 mm or more and 5 mm or less,
Wherein the plate-like portion satisfies the following orientation property,
[Orientation]
A region from the surface of the plate portion to a thickness of 1/4 in the thickness direction is a surface region and the remaining portion is an inner region,
The peak intensities of the (002) plane, (100) plane, (101) plane, (102) plane, (110) plane and (103) plane in the surface region are I _{F F} (100), I _F (101), I _F (102), I _F (110), and I _F (103)
The peak intensities of the (002) plane, the (100) plane, the (101) plane, the (102) plane, the (110) plane and the (103) plane in the inner region are I _{C C} (100), I _C (101), I _C (102), I _C (110), and I _C (103)
The degree of orientation of the plane (002) in the surface _{region: I F (002) / {} I F (100) + I F (002) + I F (101) + I F (102) + I F (110) + I _F (103)} to the bottom surface peak ratio (O _F )
The degree of orientation of the plane (002) in the inner _{region: I C (002) / {} I C (100) + I C (002) + I C (101) + I C (102) + I C (110) + I _C (103)} is the bottom surface peak ratio (O _C )
Wherein a ratio O _F / O _C of a bottom surface peak ratio (O _F ) of the surface region to a bottom surface peak ratio (O _C ) of the inner region satisfies 0.95? O _F / O _C ?
In the magnesium alloy material,
A process for preparing a plate-like material obtained by continuously casting a molten magnesium alloy by a double-roll casting method, the process comprising the steps of:
Rolling a plurality of passes on the material to produce a plate-shaped magnesium alloy material having a thickness of 1.5 mm or more and 5 mm or less,
In the rolling step, the rolling is performed at least one pass at a reduction rate of 30% or more per pass, the reduction rate of each of the remaining passes is at least 10%, and at least one pass is performed by heating the material to 150 deg. , And heating the rolled roll to 100 to 250 캜. The method of claim 1, wherein the mean grain of the inner area of the average crystal grain size of the surface area of the D _F, the average crystal grain diameter (D _F) at the time of the average crystal grain size of the inner region to the D _C, the surface area particle diameter (D _C) ratio of: D _C / D _F is _{2 / 3≤D C / D F ≤3} / 2 satisfy and, a magnesium alloy member, characterized in that D _F D and _C ≥3.5 ㎛. The method of claim 1 or claim 2, wherein the Vickers hardness (H _F) of the surface area when the Vickers hardness (Hv) of the surface area of the Vickers hardness (Hv) of the H _F, the inner region to the H _C Wherein a ratio of a Vickers hardness (H _C ) of the internal region to H _C / H _F satisfies 0.85? H _C / H _F? 1.2. The magnesium alloy material according to claim 1 or 2, wherein the magnesium alloy contains 5.0 mass% or more and 12 mass% or less of Al as an additive element. 4. The magnesium alloy material according to claim 3, wherein the magnesium alloy contains 5.0% by mass or more and 12% by mass or less of Al as an additive element. A manufacturing method of a magnesium alloy material for producing a magnesium alloy material by rolling a material made of a magnesium alloy,
A process for preparing a plate-like material obtained by continuously casting a molten magnesium alloy by a double-roll casting method, the process comprising the steps of:
Rolling a plurality of passes on the material to produce a plate-shaped magnesium alloy material having a thickness of 1.5 mm or more and 5 mm or less,
In the rolling step, the rolling is performed at least one pass at a reduction rate of 30% or more per pass, the reduction rate of each of the remaining passes is at least 10%, and at least one pass is performed by heating the material to 150 deg. , And heating the rolled roll to 100 to 250 캜.