JP5757104B2 - Magnesium alloy material and manufacturing method thereof - Google Patents

Description

  The present invention relates to various members such as parts of transportation equipment such as automobiles, railway vehicles, airplanes, bicycle parts, casings of electronic / electric equipment, and other structural members, and magnesium alloy materials suitable for constituent materials of the members, And a manufacturing method thereof. In particular, the present invention relates to a magnesium alloy material that is thick and excellent in plastic workability such as press working.

  It is lightweight as a component material for various components such as casings for portable electronic and electrical equipment such as mobile phones and notebook personal computers, automobile parts such as wheel covers and paddle shifts, railway vehicle parts, and bicycle parts such as frames. Magnesium alloys excellent in specific strength and specific rigidity have been studied. As for the members made of magnesium alloy, casting materials (ASTM standard AZ91 alloy) by die casting method or thixo mold method are mainly used. In recent years, a press-worked material obtained by press-working a plate made of a magnesium alloy for extension represented by ASTM standard AZ31 alloy is being used. In Patent Document 1, a continuous cast material made of various magnesium alloys such as AZ91 alloy is produced using a twin roll casting method, and a rolled plate obtained by rolling the continuous cast material is subjected to press working. Is disclosed.

International Publication No. 2006/003899

  Conventionally, a relatively thin plate material having a thickness of 1 mm or less has been studied as a material of a plastic work material such as a press work material, focusing on the light weight of a magnesium alloy. However, with the expansion of the range of applications of magnesium alloys, not only the above-mentioned thin plates, but also the development of thick plates with a focus on specific strength and specific rigidity, specifically thick plates with a thickness of 1.5 mm or more Is desired. Conventionally, a material such as a magnesium alloy plate having such a thickness and excellent plastic workability, a manufacturing method thereof, and a plastic work material such as a press work material produced using this plate have not been sufficiently studied.

  If a die casting method or a thixo mold method is used, a thick magnesium alloy plate can be obtained. However, in casting materials such as die-cast materials, internal defects such as nests are likely to exist, and the composition and structure are not uniform, such as locally high concentrations of additive element components and random orientation of crystal grains. It is easy to become. Further, in a cast material such as a die-cast material, precipitates are likely to precipitate at the grain boundaries. Casting materials such as die-cast materials are inferior in plastic workability such as press work, because the defect portion and the precipitates at the crystal grain boundaries are the starting points of fracture. Further, a cast material such as a die-cast material is inferior in mechanical properties such as strength and hardness to a plastic material such as a press-worked material due to the above internal defects.

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

  Compared to die-casting materials and thixo-mold materials, magnesium alloy materials that have been subjected to plastic processing (primary processing) such as rolling are the same by reducing defects during casting and making crystals finer. Even with this composition, mechanical properties such as strength, hardness and toughness, corrosion resistance, and plastic workability are excellent. A magnesium alloy material obtained by subjecting the magnesium alloy material subjected to the primary processing to plastic processing (secondary processing) such as press working is also excellent in the mechanical characteristics and corrosion resistance. In particular, when a continuous cast material manufactured by a continuous casting method such as a twin roll casting method is used as a material for the primary work material, the cast material has less segregation and coarse crystal precipitates than plastics such as die casting, and is plastic. Excellent workability. Therefore, the present inventors rolled the continuous cast material under various conditions to produce a thick magnesium alloy plate having a thickness of 1.5 mm or more, and investigated its plastic workability. Here, the rolled material (rolled plate) of the magnesium alloy generally has a texture in which the bottom surface of the magnesium alloy crystal is oriented parallel to the rolling direction (the direction in which the rolled material proceeds). However, if the degree of integration in the texture is strong, there is a disadvantage that the formability is impaired during plastic processing such as press processing. The inventors of the present invention (1) when the texture in the surface side portion of the rolled plate is stronger than the texture in the inner portion of the rolled plate, the decrease in formability (plastic workability) is large. 2) When trying to obtain a thick rolled material by subjecting a thick material to conventional rolling, the texture on the surface side part develops compared to the internal part, and the thickness is 1.5 mm or less. As a result, it was found that the same moldability as that of the material was not obtained. Furthermore, the present inventors have obtained the knowledge that a magnesium alloy plate produced under specific conditions is excellent in plastic workability such as press working while being thick. The present invention is based on the above findings.

The magnesium alloy material of the present invention is made of a magnesium alloy, has a plate-like portion having a thickness of 1.5 mm or more, and the plate-like portion satisfies the following orientation.
[Orientation]
The area from the surface of the plate-shaped part to 1/4 of the thickness in the thickness direction is the surface area, the remaining area is the internal area,
The X-ray diffraction peak intensities of the (002) plane, (100) plane, (101) plane, (102) plane, (110) plane, and (103) plane in the surface region are respectively I _F (002), I _F (100), I _F (101), I _F (102), I _F (110), and I _F (103),
The peak intensities of X-ray diffraction of the (002) plane, (100) plane, (101) plane, (102) plane, (110) plane, and (103) plane in the internal region are I _C (002), I _C (100), I _C (101), I _C (102), I _C (110), and I _C (103)
Orientation degree of (002) plane 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)} a bottom peak ratio O _F,
Orientation degree of (002) plane in the internal region: I _C (002) / {I _C (100) + I _C (002) + I _C (101) + I _C (102) + I _C (110) + I _C (103)} when the the bottom peak ratio O _C,
The ratio of the bottom peak ratio O _F of the surface area relative to the bottom surface peak ratio O _c of the internal region: O _F / O _c satisfies the _{0.95 ≦ O F / O c ≦} 1.05.

The said magnesium alloy material of this invention can be manufactured with the following this invention manufacturing method, for example. The method for producing a magnesium alloy material according to the present invention relates to a method for producing a magnesium alloy material by rolling a material made of a magnesium alloy, and includes the following preparation step and rolling step.
Preparation step: A step of preparing a plate-like material obtained by continuously casting a molten magnesium alloy by a twin roll casting method.
Rolling step: A step of producing a plate-like magnesium alloy material having a thickness of 1.5 mm or more by subjecting the material to rolling in a plurality of passes.
In this rolling process, at least one pass of rolling with a reduction rate of 25% or more per pass is performed, and the reduction rate of each remaining pass is set to 10% or more.
The reduction ratio (%) means {(thickness t _b of material before rolling−thickness t _a of material after rolling) / thickness t _b of material before rolling} × 100.

  According to the production method of the present invention, the reduction rate per pass is 25% by using a continuous casting material that has few or substantially no defects, crystal precipitates, segregation, or the like as a starting point such as cracks. The relatively strong rolling as described above can be performed satisfactorily. Moreover, in this rolling with a high rolling reduction, plastic working can be performed uniformly over the entire region in the thickness direction of the material. That is, by performing at least one pass of rolling with a high rolling reduction, uniform processing can be performed from the surface of the material to the inside. 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)) having a uniform structure over the entire region in the thickness direction can be obtained. . This structure is a texture that is arranged mainly so that the bottom surface of the magnesium alloy crystal is parallel to the rolling direction (a texture that is arranged so that the c-axis of the crystal is perpendicular to the rolling direction).

  When the magnesium alloy material of the present invention is a rolled plate subjected to the above-described specific rolling (that is, when the entire magnesium alloy material of the present invention is composed of a plate-shaped portion), the thickness thereof as described above. It is composed of a uniform structure over the entire direction (surface to center to surface). By being composed of such a uniform structure, the magnesium alloy material of the present invention is excellent in plastic workability such as press working while being thick. Therefore, this plate-like magnesium alloy material can be suitably used as a material for plastic working such as press working. In addition, this magnesium alloy material is composed of a uniform structure, and thus has uniform characteristics (mechanical characteristics such as hardness, strength, impact resistance, toughness, corrosion resistance, vibration damping, etc.). Further, when the plate-like magnesium alloy material is used as a material for plastic working, a plastic working material (one form of the magnesium alloy material of the present invention) such as a press working material having excellent dimensional accuracy can be obtained. The obtained plastic working material is also composed of a uniform structure over the entire region in the thickness direction, that is, substantially maintains the structure of the material. Therefore, the obtained plastic working material such as press working material also has the above-mentioned uniform characteristics.

As an embodiment of the magnesium alloy material of the present invention, when the average crystal grain size of the surface region is D _F and the average crystal grain size of the internal region is D _c , the internal region with respect to the average crystal grain size D _F of the surface region is The ratio of the average crystal grain diameter D _{c in} the region: D _c / D _F satisfies 2/3 ≦ D _c / D _F ≦ 3/2, and D _F and D _c ≧ 3.5 μm .

  According to the said form, since it is a uniform particle diameter over the whole area of the thickness direction, it is excellent by plastic workability.

As one embodiment of the magnesium alloy material of the present invention, when the Vickers hardness (Hv) of the surface region is H _F and the Vickers hardness (Hv) of the internal region is H _c , the internal to the Vickers hardness H _F of the surface region the ratio of the Vickers hardness H _c region: H _c / H _F may include forms that satisfies _{0.85 ≦ H c / H F ≦} 1.2.

  According to the above aspect, since it has a uniform hardness over the entire region in the thickness direction, for example, a part of the magnesium alloy material is subjected to grinding or chemical treatment, and the surface side portion is partially applied. Even when is removed, the surface hardness of the magnesium alloy material after the processing or treatment does not substantially change from that before the processing or treatment, and has stable surface properties. Therefore, according to the said form, when performing surface treatments, such as a chemical conversion treatment, in the post process, the said process can be performed stably.

  The magnesium alloy material of the present invention can be composed of magnesium alloys (remainder Mg and impurities) containing various elements as additive elements. In particular, alloys with high concentrations of additive elements, specifically magnesium alloys with a total content of 5.0% by mass or more, depend on the type of additive elements, but mechanical properties such as strength and hardness, corrosion resistance, and flame resistance Excellent in various properties such as heat resistance.

  Specific additive elements are selected from Al, Zn, Mn, Si, Be, Ca, Sr, Y, Cu, Ag, Sn, Li, Zr, Ce, Ni, Au, and rare earth elements (excluding Y and Ce) And at least one element. Examples of the impurity include Fe.

  In particular, Mg-Al alloys containing Al are excellent in corrosion resistance and mechanical properties such as strength and hardness. Therefore, as an embodiment of the magnesium alloy material of the present invention, an embodiment in which the magnesium alloy contains 5.0% by mass or more and 12% by mass or less of Al as an additive element. The higher the Al content, the higher the above effect tends to be, and 7 mass% or more, and preferably 7.3 mass% or more are preferable. However, if the Al content exceeds 12% by mass, the plastic workability is lowered, so the upper limit is preferably 12% by mass, and more preferably 11% by mass. In particular, the form containing 8.3 mass% to 9.5 mass% of Al is more excellent in strength and corrosion resistance. The total content of each element other than Al is 0.01% by mass or more and 10% by mass or less, preferably 0.1% by mass or more and 5% by mass or less.

  More specific compositions of Mg-Al alloys include, for example, AZ-based alloys according to ASTM standards (Mg-Al-Zn-based alloys, Zn: 0.2 mass% to 1.5 mass%, such as AZ31 alloy, AZ61 alloy, AZ91 alloy) Etc.), AM alloy (Mg-Al-Mn alloy, Mn: 0.15 mass% to 0.5 mass%), AS alloy (Mg-Al-Si alloy, Si: 0.01 mass% to 20 mass%), Mg -Al-RE (rare earth element) alloy, AX alloy (Mg-Al-Ca alloy, Ca: 0.2 mass% to 6.0 mass%), AJ alloy (Mg-Al-Sr alloy, Sr: 0.2 mass) % To 7.0% by mass). Examples of the alloy containing 8.3 mass% to 9.5 mass% of Al further include an Mg—Al—Zn alloy containing 0.5 mass% to 1.5 mass% of Zn, typically AZ91 alloy.

  In addition, it contains at least one element selected from Y, Ce, Ca, Si, Sn and rare earth elements (excluding Y and Ce) in a total amount of 0.001% by mass or more, preferably a total of 0.1% by mass or more and 5% by mass or less. The magnesium alloy with the balance being Mg and impurities is excellent in heat resistance and flame retardancy. When the rare earth element is contained, the total content is preferably 0.1% by mass or more, and particularly when Y is contained, the content is preferably 0.5% by mass or more.

  The magnesium alloy material of the present invention is thick and excellent in plastic workability. The manufacturing method of the magnesium alloy material of the present invention can manufacture a magnesium alloy material that is thick and excellent in plastic workability.

The present invention will be described in detail below.
[Magnesium alloy material]
(composition)
The magnesium alloy material of the present invention is composed of a magnesium alloy containing 50% by mass or more of Mg and typically the additive elements described above.

(Form)
The plate-like portion provided in the magnesium alloy material of the present invention has a pair of parallel surfaces, and the interval between both surfaces (distance between both surfaces) is substantially uniform, that is, a portion where the thickness is uniform. say. If the magnesium alloy material of the present invention has a plate-like part in a part thereof, the cutting process such as a form in which a boss is joined to the other part, a form having a groove, a form having a hole penetrating the front and back, etc. The form which has the part from which thickness differs locally by processing, such as is permitted.

  A typical form of the magnesium alloy material of the present invention having the plate-like portion includes a form (magnesium alloy plate) whose whole is plate-like. The shape (planar shape) of the magnesium alloy plate can take various shapes such as a rectangle and a circle. Moreover, this magnesium alloy plate can take any form of the coil material which wound up the continuous long material, and the short material of 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 straightened plate subjected to heat treatment or correction described later, a rolled plate, a heat-treated plate, a polished plate obtained by polishing or coating the straightened plate, a coated plate, or the like can be given. .

  In addition, the magnesium alloy material of the present invention is a molded body obtained by subjecting the magnesium alloy sheet to plastic processing (secondary processing) such as press working such as bending or drawing, and the plastic working is partially applied to the plastic. Examples include a partially processed material having a processed part (however, at least a part of the plate-shaped part is included). The molded body is, for example, a cross-sectional box having a top plate portion (bottom surface portion) and a side wall portion erected from the periphery of the top plate portion, a frame-like frame body, and the top plate portion being a disc. For example, a covered cylindrical body having a cylindrical side wall portion may be used. The top plate portion corresponds to a plate-like portion. Depending on the desired application, the form of the magnesium alloy material can be selected.

(thickness)
One feature of the magnesium alloy material of the present invention is that the plate-like portion has a thickness of 1.5 mm or more. As the thickness, an arbitrary value of 1.5 mm or more can be selected according to a desired application. However, in order to increase the thickness of the plate-shaped portion, it is necessary to increase the thickness of the casting material. When the cast material is thickened, the rolling property is deteriorated due to defects 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 (one form of the magnesium alloy material of the present invention) can be produced with high productivity.

  In the case where the magnesium alloy material of the present invention is the molded body or the partially processed material, the portion where the deformation due to plastic processing is small (typically, the plate-like portion) is the structure of the magnesium alloy plate that is the material of the plastic processing. And generally maintain mechanical properties.

(Organization)
<Orientation>
One feature of the magnesium alloy material of the present invention is that at least the plate-like portion is composed of a structure having a uniform texture throughout the entire thickness direction. A form in which the ratio of the bottom peak ratio O _F / O _c described above satisfies 1.00 ≦ O _F / O _c ≦ 1.05 is particularly excellent in plastic workability. In addition, the obtained plastic working material (molded body) and the partially processed material have small variations in mechanical characteristics throughout the whole.

<Average crystal grain size>
A typical form of the magnesium alloy material of the present invention includes a form in which the crystal grain size is uniform over the entire region in the thickness direction as described above. In this form, when a plastic working such as press working is performed, a plastic working material (molded body) or a partially processed material that can be uniformly deformed and has excellent dimensional accuracy can be obtained. The smaller the difference in the average crystal grain size between the surface region and the internal region, the more uniformly the plastic working is expected, so the above-mentioned ratio of the average crystal grain size: D _c / D _F is particularly 1 ≦ D _c / A form satisfying D _F ≦ 1.4 is more excellent in plastic workability. In addition, the obtained plastic working material (molded body) and the partially processed material have small variations in mechanical characteristics throughout the whole.

  In addition, when producing a thick plate-like magnesium alloy material having a thickness of 1.5 mm or more by rolling as described above, the particle size is uniform and fine throughout the entire thickness direction. There is a limit to making the particle size small, and the minimum value of the average crystal particle size is about 3.5 μm. However, since the smaller the crystal grain size, the better the plastic workability, the average crystal grain size of the plate-like part is preferably 20 μm or less, particularly preferably 10 μm or less. The average crystal grain size varies depending on the rolling reduction in the rolling process and the heating temperature of the material, and tends to be smaller as the rolling reduction is higher and the heating temperature is lower. Further, the average crystal grain size of the surface region where plastic working is easily applied during rolling tends to be smaller than that of the internal region.

(Mechanical properties)
The magnesium alloy material of the present invention is superior in mechanical properties such as strength, hardness, toughness and the like in the thickness direction as compared with a cast material such as a die-cast material due to rolling. And uniformly having the mechanical characteristics. For example, as described above, the Vickers hardness is a uniform value. Since the higher the mechanical weak point difference Vickers hardness is small in the surface region and the interior region (low hardness portion) is not substantially present, the ratio of the Vickers hardness H _c: H _c / H _F is 0.95 ≦ H _c / H More preferably, _F ≦ 1.1. Although the absolute value of the Vickers hardness depends on rolling conditions such as the rolling reduction and the heating temperature of the material, the absolute value of Vickers hardness tends to increase as the content of the additive element increases. In addition, the Vickers hardness of the surface region where plastic working is easily performed during rolling tends to be larger than that of the internal region. When the magnesium alloy material of the present invention is a plastically processed material (molded body) or a partially processed material, the hardness tends to further increase due to work hardening.

(Other configurations)
If the anticorrosive treatment such as chemical conversion treatment or anodizing treatment is performed on at least a part of the surface of the magnesium alloy material of the present invention to provide an anticorrosion layer, the corrosion resistance is excellent. Moreover, if it is set as the form which provides a coating layer by coating at least one part of the surface of this invention magnesium alloy material, designability and commercial value can be improved.

[Production method]
Hereafter, each process of the manufacturing method of this invention mentioned above is demonstrated in detail.
(Preparation process)
<Casting>
In the production method of the present invention, a continuous casting material is used as a starting material. Since the continuous casting method can be rapidly solidified, segregation and oxides can be reduced even when the content of additive elements is large, and the formation of coarse crystal precipitates exceeding 10 μm that can be the starting point of cracking can be suppressed. . Therefore, a cast material excellent in plastic workability such as rolling can be obtained. In the continuous casting method, a long cast material can be continuously produced, and the long material can be used as a raw material. When the material is long, a long rolled material can be manufactured. There are various continuous casting methods such as a twin roll method, a twin belt method, and a belt-and-wheel method, but the twin roll method and the twin belt method, particularly the twin roll method are suitable for the production of a plate-shaped cast material. In particular, it is preferable to use a continuous cast material produced by the casting method described in Patent Document 1. The thickness, width, and length of the cast material can be appropriately selected so that a desired rolled material (rolled plate) can be obtained. Since the thickness of the cast material is likely to be segregated if it is too thick, it is preferably 10 mm or less, particularly preferably 5 mm or less. When making the obtained continuous cast material into a long material, if it winds up in a cylindrical shape and uses it as a coil material, it will be easy to convey to the following process. If the part immediately before winding in the cast material is rolled up in a state heated to about 100 ° C. to 200 ° C., the content of additive elements such as AZ91 alloy is high, and even if it is an alloy type that is liable to crack, it is easy to bend, Even when the take-up diameter is small, it can be wound up without causing cracks. A sheet material obtained by cutting the obtained continuous cast material into an appropriate length can be used as a raw material. In this case, a rolled material (rolled sheet) having a predetermined length is obtained.

<Solution>
When the solution treatment is performed before rolling the cast material, the composition of the cast material can be homogenized or the toughness can be enhanced by sufficiently dissolving an element such as Al. Examples of the solution treatment conditions include heating temperature: 350 ° C. or higher, particularly 380 ° C. or higher and 420 ° C. or lower, holding time: 1 hour or longer and 40 hours or shorter. In the case of an Mg—Al-based alloy, it is preferable that the holding time be longer as the Al content is higher. Further, in the cooling step from the above holding time, if the cooling rate is increased by using forced cooling such as water cooling or blast (preferably 50 ° C./min or more), precipitation of coarse precipitates can be suppressed.

<Rolling>
The cast material or solution treatment material is used as a raw material, and this material is subjected to multiple passes of rolling. It is preferable that at least one pass includes warm rolling or hot rolling performed by heating a raw material (a cast material, a solution treatment material, a processed material during rolling) to 150 ° C. or more and 400 ° C. or less. By heating the material to the above temperature, even when the rolling reduction per pass is increased, cracks and the like are less likely to occur during rolling, and the higher the temperature, the less the cracks, etc. Deterioration due to seizure of the material surface and thermal deterioration of the rolling roll can be suppressed. Therefore, the heating temperature is preferably 350 ° C. or lower, more preferably 300 ° C. or lower, and particularly preferably 150 ° C. or higher and 280 ° C. or lower. You may heat not only a raw material but a rolling roll. As for the heating temperature of a rolling roll, 100 to 250 degreeC is mentioned.

  In particular, in the production method of the present invention, rolling in which the rolling reduction per pass is 25% or more (hereinafter, this rolling is referred to as strong work rolling) is performed by one pass or multiple passes. The high work rolling with such a high rolling reduction is preferably the warm rolling or hot rolling. The higher the rolling reduction, the more plastic material can be processed from the surface to the inside, and a rolled material with a uniform structure can be obtained. Therefore, the rolling reduction of high work rolling is 30% or more per pass. Is preferable, and can be appropriately selected within a range in which the material does not crack. When the rolling reduction rate of each pass other than the high-strength rolling (hereinafter referred to as general rolling) is 10% or more, the rolling is performed uniformly and sufficiently over the entire thickness direction of the material. be able to. As described above, the higher the rolling reduction of each pass of general rolling, the more plastic processing can be performed, so that it can be made 15% or more, and further 20% or more per pass. The number of passes and the rolling reduction of the high work rolling / general rolling can be appropriately selected according to the total rolling reduction.

  Conditions such as the heating temperature of the material, the temperature of the rolling roll, and the rolling reduction can be changed for each pass. Therefore, the rolling reduction rate of each pass may be the same or different. Further, intermediate heat treatment may be performed between passes. By performing the intermediate heat treatment, it is possible to remove and reduce distortions, residual stresses, and the like introduced into the material before the heat treatment, and to easily perform rolling after the heat treatment. The conditions for the intermediate heat treatment include heating temperature: 150 ° C. to 350 ° C. (preferably 300 ° C. or less, more preferably 250 ° C. to 280 ° C., holding time: 0.5 hour to 3 hours). Moreover, you may perform final heat processing on the said conditions after rolling. In addition, in the above rolling, when a lubricant is appropriately used, the frictional resistance during rolling can be reduced, and the material can be prevented from being seized and easily rolled.

  In addition, the edge of the cast material before rolling may be trimmed to prevent the crack from progressing when the edge is cracked during rolling. You may trim in order to adjust suitably.

<Other processing>
≪Polishing≫
You may grind | polish after the said rolling. By polishing, it is possible to remove and reduce the lubricant used during rolling, scratches and oxide films present on the surface of the rolled material, and the like. For the polishing, it is preferable to use a grinding belt because it can be easily and continuously polished even if the material is a long material. The polishing is preferably wet in order to prevent the powder from scattering.

≪Correction≫
Correction may be performed after the rolling or after the polishing. By performing the correction, the flatness can be improved, and plastic processing such as press processing can be performed with high accuracy. For correction, a roll leveler device in which a plurality of rollers are arranged in a staggered manner can be suitably used. The correction may be performed, for example, in a state where the material is heated to 100 ° C. to 300 ° C., particularly 150 ° C. to 280 ° C. (warm correction).

≪Plastic processing≫
When the magnesium alloy material of the present invention is a partially processed material having a molded body or a plastic processing portion, at least a part of the material that has undergone the rolling process described above (rolled material, abrasive material, correction material described above) and so on. It can be manufactured by a manufacturing method including a plastic processing step for performing plastic processing. This plastic working is preferably performed in a temperature range of 200 ° C. to 300 ° C., because the plastic workability of the material is improved. In addition, heat treatment can be performed after the plastic working to remove strain and residual stress introduced by the plastic working and to improve the mechanical characteristics. Examples of the heat treatment conditions include a heating temperature: 100 ° C. to 300 ° C. and a heating time: about 5 minutes to 60 minutes.

≪Surface treatment≫
When the magnesium alloy material of the present invention is provided with the anticorrosion layer and the coating layer, at least a part of the material that has undergone the rolling process described above, or at least a part of the material that has undergone the plastic working process, It can manufacture by the manufacturing method which comprises the surface treatment process which performs. In addition, at least one kind of processing selected from hairline processing, diamond cutting processing, shot blasting processing, etching processing, and spin cutting processing may be applied to at least a part of the material. By performing these surface treatments, corrosion resistance and mechanical protection functions can be improved, and design properties, metal texture, and commercial value can be increased.

Hereinafter, more specific embodiments of the present invention will be described with reference to test examples.
[Test example]
A material composed of a magnesium alloy having the following composition was rolled under various conditions to produce a magnesium alloy plate having a thickness of 1.5 mm or more, and the orientation, crystal grain size, and Vickers hardness were examined.

  In this test, a magnesium alloy plate made of a magnesium alloy (Mg-8.9 mass% Al-0.6 mass% Zn) having a composition equivalent to AZ91 alloy and a magnesium alloy (Mg-3.0 mass% Al--) having a composition equivalent to AZ31 alloy were used. A magnesium alloy plate made of 0.7 mass% Zn) was produced.

  Using the magnesium alloy of each composition described above, a long cast plate (thickness 4.5 mm (4.50 mm to 4.51 mm) x width 320 mm) is produced by a twin roll continuous casting method, and once wound up, a cast coil material is obtained. Produced. Each cast coil material was subjected to a solution treatment at 400 ° C. for 24 hours. The material obtained by rewinding the solid solution coil material that has undergone solution treatment is subjected to rolling in a plurality of passes under the rolling conditions shown in Table 1, and has a thickness of 2.0 mm (2.00 mm to 2.01 mm) or 1.5 mm (1.50 mm to 1.51). mm) rolled material (magnesium alloy plate). Each pass was warm-rolled (material heating temperature: 250 ° C. to 280 ° C., roll temperature: 100 ° C. to 250 ° C.). The thickness of the cast material, the thickness of the processed material in the middle of rolling, and the thickness of the obtained magnesium alloy plate are all 50 mm from the center in the width direction of the plate to be measured and both edges in the width direction. It was set as the average of the thickness of a total of three points.

[Orientation]
For each of the obtained magnesium alloy plate subjected to X-ray diffraction, the ratio of the bottom peak ratio O _F surface area relative to the bottom surface peak ratio O _c of the inner region was investigated with O _F / O _c. The results are shown in Table 2. Bottom peak ratio O _F surface area, subjected to X-ray diffraction with respect to the surface of the magnesium alloy plate, the bottom peak ratio O _c of the inner region, the first surface from the thickness in the thickness direction of the magnesium alloy plate The region up to / 4 (surface region) was chemically removed to expose the interior, and X-ray diffraction was performed on this exposed surface. And measure the peak intensity of (002) plane, (100) plane, (101) plane, (102) plane, (110) plane, and (103) plane of each region, and use this measurement result. to determine the O _F / O _c.
Bottom 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)}
Bottom 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 grain size]
For each of the obtained magnesium alloy plates, the average crystal grain size (μm) of the inner region and the surface region was measured based on “steel-crystal grain size microscopic test method JIS G 0551 (2005)”. Here, a cross section in the thickness direction (cross section and longitudinal section) is taken for each magnesium alloy plate, each cross section is observed with an optical microscope (400 times), and the surface region in each cross section (from the surface to the thickness direction) 3 areas (up to 1/4 of the thickness) and internal areas (remaining areas excluding the surface area), 3 fields of view (total number of fields of view: 6), average grain size for each field of view Asked. Table 2 shows the average value (D _F ) of the average crystal grain size of a total of six views in the surface region and the average value (D _C ) of the average crystal grain size of a total of six views in the internal region. Further, the ratio of the average crystal grain size D _{c in} the inner region to the average crystal grain size D _F in the surface region: D _c / _DF was also obtained. The results are shown in Table 2.

[Vickers hardness]
The Vickers hardness (Hv) of the internal region and the surface region was examined for each obtained magnesium alloy plate. Vickers hardness, as with the measurement of the average crystal grain size, taken in the thickness direction of the cross section (cross section and longitudinal section) for each magnesium alloy plates, Vickers hardness H _F in the surface region, the surface of each section measured by pressing an indenter to the area, the Vickers hardness H _F in the internal region was measured by pressing an indenter to the internal area of each cross section. Table 2 shows the average value (H _F ) of the Vickers hardness of both cross sections in the surface region and the average value (H _C ) of the Vickers hardness of both cross sections in the internal region. The ratio of the Vickers hardness H _c of the inner region to the Vickers hardness H _F of the surface area: H _c / H _F was also determined. The results are shown in Table 2.

  As shown in Tables 1 and 2, the continuous cast material is subjected to both rolling with a rolling reduction of 25% or more per pass and rolling with a rolling reduction of 10% or more per pass. It can be seen that a magnesium alloy plate (magnesium alloy material) having a thickness of 1.5 mm or more, having a specific orientation and having a uniform structure in the thickness direction can be obtained. . It can also be seen that this magnesium alloy plate has uniform mechanical properties.

  Each magnesium alloy plate obtained was pressed. The press working conditions were a heating temperature of the magnesium alloy plate: 250 ° C. to 270 ° C. As a result, sample Nos. A, B, D, E, G, H, J, and K having a specific orientation and a uniform structure in the thickness direction are excellent in press workability. The dimensional accuracy was excellent. Further, when the structure of the flat portion was examined in these sample Nos. A, B, D, E, G, H, J, and K, it was substantially the same as the structure of each magnesium alloy plate before press working. The specific orientation and the average crystal grain size were as described above.

  From the above test results, it is a magnesium alloy material having a plate-like portion having a thickness of 1.5 mm or more, and the plate-like portion is composed of a structure having a specific orientation and is uniform in the thickness direction. It was confirmed that it was excellent in press workability by being composed of various structures. It was also confirmed that the pressed magnesium alloy material was composed of a uniform structure.

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

  The magnesium alloy material of the present invention can be suitably used for members in various fields such as automobile parts, railway vehicle parts, aircraft parts, bicycle parts, parts of various electronic and electric devices, and constituent materials of the members. it can. The manufacturing method of this invention magnesium alloy material can be utilized suitably for manufacture of the said this invention magnesium alloy material.

Claims (5)

A magnesium alloy material made of a magnesium alloy and having a plate-like portion,
The thickness of the plate-like portion is 1.5 mm or more and 5 mm or less ,
The said plate-shaped part satisfy | fills the following orientation, The magnesium alloy material characterized by the above-mentioned.
[Orientation]
The area from the surface of the plate-like part to 1/4 of the thickness in the thickness direction is the surface area, the remainder is the internal area,
The X-ray diffraction peak intensities of the (002) plane, (100) plane, (101) plane, (102) plane, (110) plane, and (103) plane in the surface region are I _F (002), I _F (100), I _F (101), I _F (102), I _F (110), and I _F (103),
The X-ray diffraction peak intensities of the (002) plane, (100) plane, (101) plane, (102) plane, (110) plane, and (103) plane in the internal region are respectively I _C (002), I _C (100), I _C (101), I _C (102), I _C (110), and I _C (103)
Orientation degree of (002) plane 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)} a bottom peak ratio O _F,
Orientation degree of (002) plane 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)} when the the bottom peak ratio O _C,
The ratio of the bottom peak ratio O _F of the surface region relative to the bottom surface peak ratio O _C of the interior region: O _F / O _C satisfies the _{0.95 ≦ O F / O C ≦} 1.05. The average crystal grain diameter D _F of the surface region, when the average crystal grain size of the inner region and D _c, the ratio of the average crystal grain size D _c of the inner region to the average grain diameter D _F of the surface area : D _c / D _F is, satisfies the _{2/3 ≦ D c / D} F ≦ 3/2, and, D _F and D _c ≧ 3.5 [mu] m der Ru請 Motomeko magnesium alloy material according to 1. Vickers hardness (Hv) H _F of the surface region, wherein the Vickers hardness of the inner region (Hv) when the H _c, the ratio of the Vickers hardness H _c of the inner region with respect to the Vickers hardness H _F of the surface area: H _c / H _{F is, 0.85 ≦ H c / H F} ≦ 1.2 and less than to請 Motomeko 1 or a magnesium alloy material according to claim 2. Wherein said magnesium alloy, the additive element you containing Al 5.0 mass% or more and 12 mass% or less 請 Motomeko 1 magnesium alloy material according to any one of claims 3. A method for producing a magnesium alloy material by rolling a material made of a magnesium alloy to produce a magnesium alloy material,
A preparation step of preparing a plate-like material having a thickness of 10 mm or less continuously cast by a twin-roll casting method of a melted magnesium alloy;
A rolling process for producing a plate-like magnesium alloy material having a thickness of 1.5 mm or more and 5 mm or less by performing a plurality of passes of rolling on the material,
In the preparation step, as the raw material, a continuous cast material is subjected to a solution treatment at 350 ° C. or higher and 420 ° C. or lower,
In the rolling step, the temperature of the material during rolling is set to 150 ° C. or higher and 280 ° C. or lower, the temperature of the rolling roll is set to 100 ° C. or higher and 250 ° C. or lower, and rolling at a rolling reduction rate of 25% or higher per pass is performed at least one pass. the rest of the manufacturing method of each path at a reduction ratio of 10% or more to luma magnesium alloy material.