KR102043287B1 - Magnesium alloy sheet and method for manufacturing the same - Google Patents

Abstract

The present invention relates to a magnesium alloy sheet and a method of manufacturing the same.
One embodiment of the present invention is based on 100% by weight of the magnesium alloy plate, Al: 0.5 to 1.5% by weight, Zn: 0.5 to 1.5% by weight, Ca: 0.1 to 1.0% by weight, Mn: 0.01 to 1.0% by weight, balance Provided is a magnesium alloy sheet containing Mg and other unavoidable impurities.

Description

Magnesium alloy sheet and its manufacturing method {MAGNESIUM ALLOY SHEET AND METHOD FOR MANUFACTURING THE SAME}

One embodiment of the present invention relates to a magnesium alloy sheet and a method of manufacturing the same.

Recently, there is an increasing interest in materials that can be reduced in weight as a structural material, and active research is being made. Therefore, there is much interest in magnesium plate material having excellent specific strength (density vs. density).

Magnesium is the lightest metal among structural metals including aluminum and steel with a density of 1.74 g / cm 3, and is a metal that is in the spotlight in the IT / Mobile field because of its excellent vibration absorption ability and electromagnetic shielding ability.

In addition, in the automotive sector, studies are being actively conducted to reduce the weight of the vehicle body due to fuel efficiency restrictions and improved performance in advanced countries, such as Europe. Magnesium is thus considered one of the alternative metals.

However, the magnesium plate has a HCP structure, which is impossible to form at room temperature because of limited deformation mechanism at room temperature. Therefore, there are some limitations in applying to the automotive industry. Several studies have been done to overcome this.

For example, there may be a double-speed rolling that varies the speed of the upper and lower rolling rolls, an ECAP process, a high temperature rolling method of rolling near the eutectic temperature of the magnesium sheet. However, all of these processes are far from commercial.

As another example, there may be a method of improvement through the alloy as in the prior patent (Publication No. 2012-0055304). Specifically, a magnesium plate containing Zn: 1 to 10% by weight and Ca: 0.1 to 5% by weight can be used. However, the plate may not be applied to the strip casting method. Accordingly, there is a lack of mass production, there is a problem that casting is difficult for a long time due to the fusion phenomenon between the casting material and the roll during a long time casting.

On the other hand, the prior patent (application number: 2015-0185017) improved the process of the existing Al: 3% by weight, Zn: 1% by weight, Ca: 1% by weight alloy was able to obtain a high molding of 7mm or more of the limit dome height. The above technique requires at least one intermediate annealing and warm forming during the rolling step, which results in a large process cost and a large investment cost for a mold / heater, etc., thus reducing productivity. The processing cost of the magnesium alloy is expensive compared to the competition material.

In addition, in the case of the high-forming E-form alloy (AZX311) sheet developed by our company, there is anisotropy in forming parts. Therefore, to provide a magnesium alloy plate solving the above problems.

The present invention provides a magnesium alloy sheet having excellent room temperature formability and not having large anisotropy of physical properties, and a method of manufacturing the same.

Specifically, the fraction of secondary phases produced by containing less aluminum can also be reduced. Accordingly, the grain boundary segregation effect is increased to improve room temperature formability.

In addition, the secondary phase stringer may be reduced by reducing the fraction of the secondary phase. Accordingly, an object of the present invention is to provide a magnesium alloy sheet material in which the difference in physical properties is not large when the sheet member is stretched in the plate width direction TD, and in the rolled direction RD.

Magnesium alloy sheet material of one embodiment of the present invention, Al: 0.5 to 1.5% by weight, Zn: 0.1 to 1.5% by weight, Ca: 0.1 to 0.5% by weight, Mn: 0.01 to 0.3% by weight, the balance Mg and other unavoidable impurities.

Al: based on 100% by weight of the magnesium alloy sheet, the Al may be 0.5 to 1.3% by weight.

The magnesium alloy plate may include a secondary phase, and an area fraction of the secondary phase may be 5% or less with respect to 100% of the total area of the magnesium alloy plate.

The secondary phase may be Al ₂ Ca, Al ₈ Mn ₅ , or a combination thereof.

The magnesium alloy plate may include a stringer, and the length of the stringer may be 50 μm or less.

At 150 ° C. or more of the magnesium alloy sheet, the limit bending radius (LBR) value of the rolling direction RD may be 0 to 0.5 R / t.

At 150 ° C. or more of the magnesium alloy sheet, the limit bending radius (LBR) value of the sheet width direction (TD) may be 0 to 0.5 R / t.

The ratio of the limit bending radius (LBR) value of the plate width direction (TD) to the rolling direction (RD) in the magnesium alloy sheet 150 ℃ or more may be 0.8 to 1.2.

The limit dome height (LDH) of the magnesium alloy sheet may be 8 mm or more.

According to another embodiment of the present invention, a method of manufacturing a magnesium alloy sheet may be based on 100 wt% of Al: 0.5 to 1.5 wt%, Zn: 0.5 to 1.5 wt%, Ca: 0.1 to 1.0 wt%, and Mn: 0.01 to 1.0 Preparing an molten alloy comprising a weight%, balance Mg, and other unavoidable impurities; casting the molten metal to prepare a cast material; rolling the cast material to prepare a rolled material; and finalizing the rolled material And annealing.

In the preparing of the molten alloy, Al: 0.5 to 1.3% by weight relative to the total 100% by weight of the molten alloy.

Casting the molten metal to prepare a casting material may be cast by a strip casting method.

The preparing of the rolled material by rolling the cast material may be performed at a rolling reduction rate of 50% or less (excluding 0%) per rolling.

Specifically, the cast material may be rolled once or twice.

More specifically, it can be rolled in the temperature range of 100 to 350 ℃.

The preparing of the rolled material by rolling the cast material may further include an intermediate annealing of the rolled material.

The intermediate annealing of the rolled material may be carried out in a temperature range of 300 to 500 ° C.

Specifically, it may be carried out for 30 minutes to 6 hours.

The final annealing of the rolled material may be carried out at 250 ° C or higher. Specifically, it may be carried out for 30 to 600 minutes.

According to one embodiment of the present invention, by controlling the fraction of the secondary phase and the secondary phase stringer according to the aluminum content, to produce a magnesium alloy sheet material having a large anisotropy when bending test in the rolling direction (RD) and the plate width direction (TD) Can be.

In addition, it is possible to simultaneously provide a magnesium alloy sheet having excellent moldability at room temperature.

FIG. 1 shows a crack formation mechanism according to a secondary phase stringer in order in the tensile test in the plate width direction TD.
Figure 2 is a SEM observation of the cross section of Example 1.
3 is a SEM observation of the cross section of Comparative Example 1. FIG.
Figure 4 is a SEM observation of the cross section generated cracks during the bending test of Comparative Example 1.
Figure 5 is a cross-sectional view of Example 2 with an optical microscope (Optical Microscopy).

Advantages and features of the present invention and methods for achieving them will be apparent with reference to the embodiments described below in detail with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below, but may be embodied in various different forms, and the present embodiments merely make the disclosure of the present invention complete, and are common in the art to which the present invention pertains. It is provided to fully inform those skilled in the art of the scope of the invention, which is to be defined only by the scope of the claims. Like reference numerals refer to like elements throughout.

Thus, in some embodiments, well known techniques are not described in detail in order to avoid obscuring the present invention. Unless otherwise defined, all terms used in the present specification (including technical and scientific terms) may be used as meanings that can be commonly understood by those skilled in the art. When any part of the specification is to "include" any component, this means that it may further include other components, except to exclude other components unless otherwise stated. In addition, singular forms also include the plural unless specifically stated otherwise in the text.

Magnesium alloy sheet material of one embodiment of the present invention, Al: 0.5 to 1.5% by weight, Zn: 0.1 to 1.5% by weight, Ca: 0.1 to 0.5% by weight, Mn: 0.01 to 0.3% by weight, based on 100% by weight Residual Mg and other unavoidable impurities.

Specifically, the Al may be 0.5 to 1.3% by weight based on 100% by weight of the magnesium alloy sheet.

Hereinafter, the reason which limited the component and composition of a magnesium alloy plate material is demonstrated.

Al may comprise as much as 0.5 to 1.5% by weight. Specifically, it may include as much as 0.5 to 1.3% by weight. More specifically, aluminum plays a role of improving moldability at room temperature, so that the aluminum may be cast through the strip casting method when the amount is included.

Specifically, the aggregate structure during the rolling step in the manufacturing method of the magnesium alloy plate to be described later is changed to a strong base surface structure. In this case, as a mechanism for suppressing the change to the basal tissue, there is a solute dragging effect. The solute traction mechanism segregates within a grain boundary, such as Ca, which has an atomic radius larger than Mg, so that the boundary mobility can be reduced when heat or deformation is applied. For this reason, base surface texture formation by dynamic recrystallization or rolling deformation during rolling can be suppressed.

Therefore, when added in excess of 1.5% by weight of aluminum, since the amount of Al ₂ Ca secondary phase is also rapidly increased, the amount of Ca segregated at the grain boundary can be reduced. Accordingly, the solute traction effect can also be reduced. In addition, as the fraction occupied by the secondary phase decreases, the stringer may also be reduced. The stringer is described in detail below.

On the other hand, if less than 0.5% by weight of aluminum, casting by the strip casting method may be impossible. Aluminum serves to improve the flowability of the molten metal, thereby preventing roll sticking. Therefore, the Mg-Zn-based magnesium alloy without addition of aluminum cannot be cast by the strip casting method due to the actual roll sticking phenomenon.

Zn may comprise as much as 0.1 to 1.5% by weight.

More specifically, zinc, when added with calcium, activates the base surface slip through the softening of the base, thereby improving the formability of the plate. However, when added in excess of 0.7% by weight may form an intermetallic compound by combining with magnesium may adversely affect the formability.

Ca may comprise as much as 0.1 to 0.5% by weight.

Calcium, when added with zinc, causes softening of the bottom surface and activates the bottom surface slip, thereby improving the formability of the sheet.

More specifically, in the method of manufacturing a magnesium alloy sheet to be described later, the aggregate structure has a characteristic of changing into a strong base surface texture. As a mechanism for suppressing the above characteristics, there is a solute dragging effect. More specifically, elements having a larger atomic radius than Mg are segregated in the grain boundaries, and thus, the boundary mobility can be reduced when heat or deformation is applied. At this time, Ca may be used as an element having an atomic radius larger than Mg. In this case, formation of the base surface texture due to dynamic recrystallization or rolling deformation during rolling can be suppressed.

However, when the amount is added in excess of 0.5% by weight, the sticking phenomenon may increase due to an increase in adhesiveness with the casting roll during strip casting. For this reason, since the fluidity | liquidity of a molten metal is reduced and casting property becomes low, productivity can be reduced.

Mn may comprise as much as 0.01 to 0.3% by weight.

Manganese forms a Fe-Mn-based compound, and serves to reduce the content of Fe in the plate. Therefore, in the case of containing manganese, it is possible to form the Fe-Mn compound in the form of dross or sludge in the molten alloy state before casting. For this reason, the board | plate material with few content of Fe components at the time of casting can be manufactured. In addition, manganese can form an Al ₈ Mn ₅ secondary phase with aluminum. From this, the amount of calcium consumed is suppressed, thereby increasing the amount of calcium segregated at the grain boundaries. Accordingly, when adding manganese, the solute traction effect can be further improved.

The magnesium alloy sheet may be segregated calcium element in the grain boundary. In this case, the calcium element may be segregated at the grain boundaries in the form of a solute, not in the form of an intermetallic compound.

More specifically, calcium is dissolved without forming a secondary phase with an element such as aluminum and is segregated at the grain boundary in the form of a solute, thereby decreasing the mobility of the grain boundary and suppressing the formation of the basal surface texture. For this reason, the magnesium alloy plate material which is excellent in moldability at normal temperature can be provided.

Therefore, the above-described magnesium alloy plate may include a secondary phase, which is Al ₂ Ca, Al ₈ Mn ₅ , or a combination thereof, with respect to 100% of the total area of the magnesium alloy plate, and the area fraction of the secondary phase may be 5% or less. . More specifically, it may be 3% or less. Even more specifically 1% or less.

This is a significantly lower value than other conventional magnesium alloy sheet containing more than 1.5% by weight of Al relative to the total weight of the magnesium alloy sheet.

By controlling the fraction of secondary phase to the minimum as mentioned above, grain boundary segregation can be improved and room temperature formability can be improved. In addition, it is possible to reduce the stringer of the secondary phase generated as the fraction of the secondary phase increases.

In the present specification, the stringer means that the secondary phases are banded together in the rolling direction RD.

Specifically, the magnesium alloy sheet includes a stringer, but the length of the stringer may be up to 50 μm or less.

If the length of the stringer ranges up to 50 μm, it may mean that the stringer is hardly included.

On the other hand, when there is a strip-shaped stringer having a secondary phase aggregated in the rolling direction (RD) up to 50㎛ may have a large physical anisotropy of the magnesium alloy sheet. Specifically, in the case of including a stringer having a maximum length of 50 μm in the rolling direction of the magnesium alloy plate, the secondary phase is broken along the stringer formed in the rolling direction RD when bending or stretching in the plate width direction TD. Cracks can easily propagate.

In particular, when the secondary phase stringer is present near the surface of the magnesium alloy plate, cracks may be more easily generated during the bending test in the plate width direction, which is a direction perpendicular to the rolling direction.

Referring to FIG. 1, crack formation mechanisms according to secondary phase stringers may be identified.

FIG. 1 shows a crack formation mechanism according to a secondary phase stringer in order in the tensile test in the plate width direction TD.

As shown in FIG. 1, it can be seen that cracks progress along the secondary phase stringer (white dot) formed in the rolling direction RD when the sheet width direction TD is pulled. That is, it is possible to derive that the crack propagation direction is parallel to the secondary phase stringer, so that the crack tends to continue along the secondary phase stringer.

Accordingly, in the case of the magnesium alloy sheet including the secondary phase stringer, the anisotropy may be inferior to that in the stretching in the rolling direction RD when the sheet is stretched in the sheet width direction TD. From this, the difference in physical properties in the case of tensioning (bending) in the rolling direction RD and in the case of stretching (bending) in the plate width direction TD can be large.

That is, in this specification, the criterion of a secondary phase stringer having a thermal effect on bending anisotropy is defined as a string word having a maximum length exceeding 50 μm.

In addition, in this specification, the board | plate material width direction TD means the direction perpendicular | vertical to the rolling direction RD.

In addition, in this specification, anisotropy means that the physical property in a rolling direction RD and a board | plate width direction TD differs. As will be described later, in the present specification, a bending test was performed in the rolling direction (RD) and the sheet width direction (TD) through the V-bending test to measure the anisotropy. Thus, the limit bending radius (LBR) value was shown through the bending test as an index of the anisotropy.

Thus, excellent anisotropy means that there is little difference in physical properties in the rolling direction RD and the plate width direction TD.

Therefore, the limit bending radius LBR may be 0 to 0.5 R / t at 150 ° C. or more in the rolling direction RD of the magnesium alloy sheet.

On the other hand, the limit bending radius (LBR) value at 150 ℃ or more of the plate width direction (TD) of the magnesium alloy sheet may be 0 to 0.5R / t.

The limit bending radius (LBR) herein refers to the ratio of the inner radius of curvature (R) of the plate to the thickness (t) of the plate after the V-bending test. Specifically, it may be the radius of curvature R of the plate / thickness (t) of the plate.

Specifically, the ratio of the limit bending radius LBR of the sheet width direction TD to the rolling direction RD of the magnesium alloy sheet may be 0.8 to 1.2.

The range means that the difference in physical properties between the rolling direction RD and the sheet width direction TD is not large.

The limit dome height (LDH) of the magnesium alloy sheet may be 8 mm or more.

In the present specification, the limit dome height (LDH) means a value derived through Ericsson test at room temperature. The moldability of a board | plate material can be compared from the said value.

More specifically, the Ericsson value refers to a height at which the plate is deformed until breakage occurs when the plate is deformed and processed into a cup. Therefore, the higher the deformation height of the magnesium alloy sheet, the larger the Ericsson value. Accordingly, moldability may be excellent.

From this, the limit dome height of the magnesium alloy sheet according to an embodiment of the present invention may be an excellent level compared to the conventional magnesium alloy.

According to another embodiment of the present invention, a method of manufacturing a magnesium alloy sheet may include: Al: 0.5 to 1.5% by weight, Zn: 0.5 to 1.5% by weight, Ca: 0.1 to 1.0% by weight, and Mn: 0.01 to 100% by weight. Preparing a molten alloy containing 1.0% by weight, balance Mg and other unavoidable impurities (S100), casting the molten metal to prepare a casting material (S200), rolling the casting material to prepare a rolled material (S300), and the final annealing the rolled material may include a (S400).

Specifically, Al: 0.5 to 1.0% by weight based on 100% by weight of the total molten alloy in the step (S100).

The specific reason for limiting the component and the composition of the molten metal is the same as the reason for limiting the component and the composition of the magnesium alloy sheet, so it is omitted.

Then in the step (S200), the casting method for preparing the casting material is die casting, direct chill casting, billet casting, centrifugal casting, tilt casting, mold gravity casting, sand casting, strip casting Law or combinations thereof. However, it is not limited thereto.

More specifically, it can cast by strip casting method. Strip casting casting may be possible with the molten alloy of the above-described composition.

More specifically, the molten metal may be cast at a rate of 0.5 to 10 mpm.

The thickness of the cast material produced therein may be 3 to 13mm, but is not limited thereto.

In the step (S300) it can be rolled at a rolling rate of 50% or less (excluding 0%) per roll. More specifically, when the rolling reduction per rolling exceeds 50%, cracking may occur during rolling.

Hereinafter, in the present specification, the reduction ratio means that the difference between the thickness of the material before passing through the rolling roll and the thickness of the material after passing through the rolling roll is multiplied by 100 after dividing by the thickness of the material before passing through the rolling roll. do.

Specifically, the cast material may be rolled once or twice or more. More specifically, when the thickness of the cast material is thick may be rolled two or more times.

More specifically, it can be rolled in the temperature range of 100 to 350 ℃. More specifically, cracking may be caused when rolling when the rolling temperature is less than 100 ° C. On the other hand, when the rolling temperature is more than 350 ℃ Ca segregation is lowered may be disadvantageous.

In addition, the step (S300) may further comprise the step (S310) of the intermediate annealing the rolled material.

Specifically, when the rolling is carried out two or more times, the intermediate annealing may be performed in the middle of the rolling step. At this time, the step (S310) may be carried out in a temperature range from 300 to 500 ℃. More specifically, it may be carried out for 30 minutes to 6 hours.

More specifically, when the intermediate annealing is performed under the above conditions, the stress generated during rolling can be sufficiently solved. More specifically, the stress can be solved through recrystallization within a range not exceeding the melting temperature of the rolled material. In addition, recrystallization may lead to the formation of grains having non-base crystal orientation.

Finally, the final annealing of the rolled material (S400) can be carried out at 250 ℃ or more. Specifically, it may be carried out at a temperature of 250 to 450 ℃.

More specifically, it may be carried out for 30 to 600 minutes.

Recrystallization can be easily formed by final annealing under the above conditions.

Hereinafter, the embodiment will be described in detail. However, the following examples are merely to illustrate the invention, but the content of the present invention is not limited by the following examples.

Production Example

Using the components and compositions shown in Table 1 below, magnesium alloy plates according to Examples and Comparative Examples were prepared.

Specifically, an alloy molten metal including the components and compositions disclosed in Table 1 below was prepared. Thereafter, the molten metal was cast by a strip casting method to prepare a casting material. Thereafter, the cast material was rolled 7 to 10 times at a reduction ratio of 25% per roll at 200 ° C.

Intermediate annealing was also performed in the middle of the said rolling. Specifically, it was carried out at 400 ℃ for 3 hours.

Finally, the rolled plate was finally annealed at 300 ° C.

The tensile strength (YS), the elongation (El), the limit dome height (LDH), and the limit bending radius (LBR) of the Examples and Comparative Examples thus prepared were evaluated and disclosed in Table 1 below.

At this time, the evaluation method of each physical property is as follows.

[Measurement of tensile strength]

The maximum tensile load until the specimen breaks, divided by the cross-sectional area of the specimen before testing. Specifically, measured using a uniaxial tensile tester at room temperature, the strain rate (strain rate) was carried out to 10 ^-3 / s.

[ Elongation  How to measure]

It is the rate at which the material stretches during the tensile test, which means the percentage of the length of the changed specimen to the length of the specimen before the test. Specifically, the same as the tensile strength measurement conditions, the length was increased compared to the initial length of the gauge (gauge) portion.

[Ericsson numerical measurement method]

Magnesium alloy plates of 50 to 60 mm in size were used, respectively, and a lubricant was used on the outer surface of the sheet to reduce friction between the plate and the spherical punch.

At this time, the die and the spherical punch were tested at room temperature.

More specifically, after inserting a magnesium alloy sheet between the upper die and the lower die, the outer peripheral portion of the sheet was fixed with a force of 10 kN, and then using the spherical punch having a diameter of 20 mm at the rate of 5 mm / min Modified to Then, after the punch is inserted until the plate is broken, it was performed by measuring the deformation height of the plate at the time of break.

The deformation height of the plate thus measured is called the Ericsson value or the limit dome height (LDH).

[Limit bending V-bending measurement  Way]

The result of the V-bending test is called the limit bending radius (LBR).

Specifically, the test specifically, the heating wire is installed in each of the apparatus consisting of a die and a punch to control the temperature to the target temperature. Both the die and the punch may have a 90 ° angle. Types of punches vary in curvature radius from 0R to 9R.

After bending the plate using the apparatus, the R of the punch is bent without cracking. At this time, the bending speed of the punch was measured to 30 to 60mm per second.

The apparatus used was a mechanical 60ton servo press, and a V-bending mold containing a punch and a die was installed in the press.

division Al Zn Mn Ca YS (Mpa) El. (%) LDH (mm) Limited bending radius (R / t) weight% Room temperaturme RT (room temperature) 150 ℃ 200 ℃ 250 ℃ Example 1 One 0.85 0.2 0.67 RD 147 22.5 8.6 2.9 0.4 0.4 0.0 TD 92 18.7 2.9 0.4 0.4 0.0 Example 2 1.03 0.45 0.12 0.19 RD 157 26.0 8.2 2.1 0.3 0.0 0.0 TD 126 26.1 2.1 0.3 0.0 0.0 Comparative Example 1 2 0.92 0.3 0.63 RD 169 25.0 8.6 2.3 1.2 0.4 0 TD 142 21.0 3.1 2.8 1.5 0.9 Comparative Example 2 3 0.8 0.3 0.62 RD 151 27.3 8.0 2.1 1.4 0.7 0.4 TD 144 15.4 4.3 3.2 2.9 2.9 Comparative Example 3 3 0.74 0.3 - RD 177 28.5 3.8 8 2.3 1.8 1.4 TD 209 24.3 8 3.6 2.3 1.8 Comparative Example 4 ZEK100 1.0 RD 223 20.4 8.1 4.1 1.5 0.9 TD 140 25.6 4.1 1.5 0.9

As disclosed in Table 1 above, the limit dome height (LDH) value of Comparative Example 1 in which the aluminum content is 2% by weight is excellent, but the limit bending radius (LBR) value is inferior.

Particularly, in Comparative Example 1, the ratio of the limit bending radius (LBR) value of the plate width direction (TD) to the limit bending radius (LBR) value of the rolling direction (RD) at 200 ° C. was 3.75, respectively, in the rolling direction and the plate width direction. It can be seen that the time anisotropy is large.

In addition, in Comparative Example 4, the anisotropy was superior to Comparative Examples 1 to 3, but it can be seen that the limit bending radius (LBR) value is inferior to Examples 1 and 2.

This can also be confirmed through the drawings of the present invention.

Figure 2 is a SEM observation of the cross section of Example 1.

As shown in Figure 2, Example 1 can be visually confirmed that there is no form of the secondary phase stringer. As a result, Example 1 may derive that the difference in physical properties during stretching in the rolling direction RD and the plate width direction TD was not large.

3 is a SEM observation of the cross section of Comparative Example 1. FIG.

On the other hand, as shown in Figure 3, Comparative Example 1 it can be seen that the second phase is agglomerated in the rolling direction and the strip-shaped stringer is included in the surface and the lower portion of the plate. In addition, the length of the stringer is confirmed to be at least 100㎛.

Therefore, the reason why the anisotropy of the board | plate width direction and the rolling direction of Comparative Example 1 is large can be derived.

Specifically, it can be confirmed through the roll of Figure 4 that the cracks generated during the bending test of Comparative Example 1.

Figure 4 is a SEM observation of the cross section generated cracks during the bending test of Comparative Example 1. Specifically, as shown in FIG. 4, Comparative Example 1 was able to identify the stringer on the surface and the portion below the surface. As a result, it can be confirmed that cracks are easily formed on the surface.

Figure 5 is a cross-sectional view of Example 2 with an optical microscope (Optical Microscopy).

As shown in FIG. 5, it can be seen that Example 2 also includes a secondary phase (black dot). However, it can be confirmed by the naked eye that the fraction of the secondary phase is much less than that of the magnesium alloy sheet.

From this, the embodiment according to the present invention controls the fraction of the secondary phase and the secondary phase stringer according to the aluminum content, so that the magnesium alloy sheet material that is not large anisotropy when bending test in the rolling direction (RD) and the plate width direction (TD) It can manufacture.

In addition, it is possible to simultaneously provide a magnesium alloy sheet having excellent moldability at room temperature.

Although the embodiments of the present invention have been described above with reference to the accompanying drawings, those skilled in the art to which the present invention pertains may implement the present invention in other specific forms without changing the technical spirit or essential features thereof. I can understand that.

Therefore, it should be understood that the embodiments described above are exemplary in all respects and not restrictive. The scope of the present invention is shown by the following claims rather than the detailed description, and all changes or modifications derived from the meaning and scope of the claims and their equivalents should be construed as being included in the scope of the present invention. .

Claims (20)

Al: 0.5 to 1.5% by weight, Zn: 0.1 to 1.5% by weight, Ca: 0.1 to 0.5% by weight, Mn: 0.01 to 0.3% by weight, balance Mg and other unavoidable impurities and,
The magnesium alloy sheet includes a secondary phase,
Magnesium alloy sheet material whose area fraction of a secondary phase is 5% or less with respect to the said magnesium alloy sheet material total area 100%.
In claim 1,
Magnesium alloy plate, Al: 0.5 to 1.3% by weight based on 100% by weight of the magnesium alloy sheet.
delete In claim 1,
The secondary phase is a magnesium alloy sheet material of Al ₂ Ca, Al ₈ Mn ₅ , or a combination thereof.
In claim 4,
The magnesium alloy sheet includes a stringer,
Magnesium alloy sheet with stringer length up to 50 µm.
In claim 5,
Magnesium alloy sheet material of the limiting bending radius (LBR) value of the rolling direction (RD) at 150 ℃ or more of the magnesium alloy sheet material is 0 to 0.5R / t.
In claim 6,
Magnesium alloy sheet material of the marginal bending radius (LBR) value of the plate width direction (TD) of 0 to 0.5R / t at 150 ℃ or more of the magnesium alloy sheet.
In claim 7,
Magnesium alloy sheet material in which the ratio of the limit bending radius (LBR) value of the plate width direction (TD) to the rolling direction (RD) to the rolling direction (RD) at 150 ℃ or more of the magnesium alloy plate.
In claim 8,
Limit dome height (LDH) of the magnesium alloy sheet is a magnesium alloy sheet of 8mm or more.
Alloy molten metal comprising Al: 0.5 to 1.5% by weight, Zn: 0.5 to 1.5% by weight, Ca: 0.1 to 1.0% by weight, Mn: 0.01 to 1.0% by weight, balance Mg and other unavoidable impurities Preparing a;
Casting the molten metal to prepare a casting material;
Rolling the cast material to prepare a rolled material; And
Method of producing a magnesium alloy sheet comprising the final annealing the rolled material.
In claim 10,
In the step of preparing the molten alloy,
A method for producing a magnesium alloy sheet, wherein Al is 0.5 to 1.3 wt% based on 100 wt% of the total molten alloy.
In claim 10,
Rolling the cast material to prepare a rolled material,
A method for producing a magnesium alloy sheet that is rolled at a rolling reduction of 50% or less (excluding 0%) per rolling.
In claim 12,
Rolling the cast material to prepare a rolled material,
Method for producing a magnesium alloy sheet material for rolling the cast material once or twice or more.
In claim 13,
Rolling the cast material to prepare a rolled material,
Method for producing a magnesium alloy sheet to be rolled at a temperature range of 100 to 350 ℃.
In claim 10,
Rolling the cast material to prepare a rolled material,
The method of manufacturing a magnesium alloy sheet further comprising the step of annealing the rolled material.
The method of claim 15,
Intermediate annealing the rolled material,
Method for producing a magnesium alloy sheet material carried out at a temperature range of 300 to 500 ℃.
The method of claim 16,
Intermediate annealing the rolled material,
Method for producing a magnesium alloy sheet material for 30 minutes to 6 hours.
In claim 10,
Final annealing the rolled material,
The manufacturing method of the magnesium alloy plate material performed at 250 degreeC or more.
The method of claim 18,
Final annealing the rolled material,
Method for producing a magnesium alloy sheet material for 30 minutes to 600 minutes.
In claim 10,
Casting the molten metal to prepare a casting material,
Method for producing a magnesium alloy sheet cast by strip casting.

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