CN108472699B - Magnesium alloy sheet material and method for producing same - Google Patents
Magnesium alloy sheet material and method for producing same Download PDFInfo
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- CN108472699B CN108472699B CN201680075821.9A CN201680075821A CN108472699B CN 108472699 B CN108472699 B CN 108472699B CN 201680075821 A CN201680075821 A CN 201680075821A CN 108472699 B CN108472699 B CN 108472699B
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- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
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- C22C23/00—Alloys based on magnesium
- C22C23/02—Alloys based on magnesium with aluminium as the next major constituent
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- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22F—CHANGING THE PHYSICAL STRUCTURE OF NON-FERROUS METALS AND NON-FERROUS ALLOYS
- C22F1/00—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working
- C22F1/06—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working of magnesium or alloys based thereon
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Abstract
The method for manufacturing the magnesium alloy sheet material of one embodiment of the invention comprises the following steps: a cast member production step (S10) of producing a cast member by casting a molten metal containing 2.7 to 5 wt% of Al, 0.75 to 1 wt% of Zn, 0.1 to 0.7 wt% of Ca, and 1 wt% or less of Mn (excluding 0 wt%), with the remainder consisting of Mg and unavoidable impurities; a homogenization heat treatment step (S20) for performing homogenization heat treatment on the cast product; and a warm rolling step (S30) for warm rolling the homogenized and heat treated cast product.
Description
Technical Field
The present invention relates to a magnesium alloy sheet material and a method for producing the same.
Background
Currently, the importance of limiting carbon dioxide emissions and new renewable energy sources is a hot topic of international society, and thus, a light alloy, which is one of structural materials, is recognized as a very attractive research field.
In particular, the density of magnesium is 1.74g/cm, compared to other structural materials such as aluminum and steel3And is the lightest metal and has various advantages such as vibration absorbing ability, electric wave blocking ability, etc., so related industries are actively developing research for applying aluminum.
Alloys containing such magnesium are currently used not only in electronic devices but also mainly in the automotive field, but their application range is further limited due to fundamental problems of corrosion resistance, flame retardancy, and moldability.
In particular, magnesium has a Hexagonal close Packed Structure (HCP) in connection with formability, and a slip system at normal temperature is insufficient, so that the processing process has many difficulties. That is, the magnesium processing process requires a large amount of heat, which directly leads to an increase in process costs.
On the other hand, the AZ-based alloy among magnesium alloys is an alloy including aluminum (Al) and zinc (Zn), and is an inexpensive alloy while ensuring appropriate physical properties such as strength and ductility to a certain extent, and is therefore a commercially available magnesium alloy.
However, the physical properties mentioned are, after all, only to an appropriate degree in magnesium alloys, having low strength compared to aluminum (Al) as a competitive material.
Therefore, it is necessary to improve physical properties such as low formability and strength of AZ-based magnesium alloys, but studies on this point are still insufficient.
Disclosure of Invention
[ problem to be solved ]
The invention aims to provide a magnesium alloy sheet material with improved strength and formability and a manufacturing method thereof.
[ MEANS FOR solving PROBLEMS ] to solve the problems
The magnesium alloy sheet material according to one embodiment of the present invention contains 2.7 to 5 wt% of Al, 0.75 to 1 wt% of Zn, 0.1 to 1 wt% of Ca, and 1 wt% or less of Mn (excluding 0 wt%), and the remaining wt% is composed of Mg and unavoidable impurities.
Ca may be contained in an amount of 0.3 to 0.8 wt%.
The magnesium alloy sheet may include 20 to 25 wt% of Al, 5 to 10 wt% of Ca, 0.1 to 0.5 wt% of Mn, 0.5 to 1 wt% of Zn, and the remaining wt% of Al-Ca secondary phase particles including Mg.
The average particle diameter of the Al-Ca secondary phase particles may be 0.01 to 4 μm.
Each 100 mu m of the magnesium alloy sheet2May comprise 5 to 15 Al-Ca secondary phase particles.
The magnesium alloy sheet material includes crystal grains, and the average grain size of the crystal grains may be 5 to 30 μm.
The thickness of the magnesium alloy sheet material may be 0.4 to 3 mm.
The method for manufacturing the magnesium alloy sheet material of one embodiment of the invention comprises the following steps: a cast member production step of producing a cast member by casting a molten metal containing 2.7 to 5 wt% of Al, 0.75 to 1 wt% of Zn, 0.1 to 1 wt% of Ca, and 1 wt% or less of Mn (excluding 0 wt%), with the remaining wt% consisting of Mg and unavoidable impurities; a homogenization heat treatment step of performing homogenization heat treatment on the cast part; and a warm rolling step of performing warm rolling on the cast product after the homogenization heat treatment.
In the casting manufacturing step, the rolling force may be 0.2 ton/mm2The above. More particularly, it may be at 1 ton/mm2The above. And even more particularly, can be at1 to 1.5 tons/mm2The above.
The cast part may be subjected to the homogenizing heat treatment at a temperature of 350 to 500 ℃ for 1 to 28 hours. More specifically, the homogenization heat treatment may be performed for 18 to 28 hours.
Warm rolling may be performed at a temperature of 150 to 350 ℃. More specifically, warm rolling may be performed at a temperature of 200 to 300 ℃.
Warm rolling may be performed a plurality of times, and is performed at a reduction ratio of 10 to 30% each time.
More than one intermediate annealing step is also included between the plurality of warm rolling.
The intermediate annealing step may be performed at a temperature of 300 to 500 ℃. More specifically, it may be carried out at a temperature of 450 to 500 ℃. Still more specifically, it may be carried out for 1 to 10 hours.
A post heat treatment step is also included after the warm rolling step.
The post-heat treatment step may be performed at 300 to 500 ℃ for 1 to 10 hours.
The method for manufacturing a magnesium alloy sheet according to an embodiment of the present invention may include: a master alloy preparation step of preparing a master alloy including, with respect to 100 wt% of the entire body, 2.7 wt% or more and 5 wt% or less of Al, 0.75 wt% or more and 1 wt% or less of Zn, 0.1 wt% or more and 1 wt% or less of Ca, more than 0 wt% and 1 wt% or less of Mn, and the balance being magnesium; a casting manufacturing step of manufacturing a casting by casting the master alloy; a homogenization heat treatment step of performing homogenization heat treatment on the cast product; a rolled material manufacturing step of manufacturing a rolled material by rolling the cast material after the homogenization heat treatment; a post-heat treatment step of performing post-heat treatment on the rolled piece; and a magnesium alloy sheet manufacturing step of performing skin pass rolling on the rolled material after the post heat treatment to manufacture a magnesium alloy sheet.
In the magnesium alloy sheet manufacturing step, the skin pass rolling may be performed once, and may be performed at a temperature ranging from 250 ℃ to 350 ℃.
By performing the magnesium alloy sheet manufacturing step, the magnesium alloy sheet manufactured is rolled at a reduction ratio of 2 to 15% with respect to the thickness of the rolled piece. Still more specifically, the magnesium alloy sheet produced is rolled at a reduction ratio of 2 to 6% with respect to the thickness of the rolled material.
The homogenizing step may include: a primary heat treatment step at a temperature range of 300 ℃ to 400 ℃; and a secondary heat treatment step in a temperature range of 400 ℃ to 500 ℃.
The one heat treatment step of the temperature interval of 300 ℃ to 400 ℃ may be performed for 5 hours to 20 hours.
The secondary heat treatment step at a temperature range of 400 to 500 ℃ may be performed for 5 to 20 hours.
The cast member may be rolled to a thickness in the range of 0.4 to 3mm by the rolled member manufacturing step.
The cast member may be rolled 1 to 15 times by the rolled member manufacturing step.
The step of manufacturing the rolled material may be carried out at 150 to 350 ℃.
The rolled piece may be annealed at a temperature ranging from 300 ℃ to 550 ℃ for 1 hour to 15 hours by the post-heat treatment step.
The Limit Dome Height (LDH) of the magnesium alloy sheet material may be above 7 mm. Still more specifically, the Limit Dome Height (LDH) of the magnesium alloy sheet material may be 8mm or more.
The magnesium alloy sheet material may have a maximum collective strength based on a (0001) plane of 1 to 4. In addition, the magnesium alloy sheet may have a yield strength of 170 to 300 MPa.
[ Effect of the invention ]
According to an embodiment of the present invention, a magnesium alloy sheet material having improved formability can be provided by removing center segregation that has conventionally been easily generated in magnesium alloy sheet materials.
Further, according to an embodiment of the present invention, a magnesium alloy sheet material having improved formability can be provided by uniformly dispersing the texture in the magnesium alloy sheet material.
In addition, according to another embodiment of the present invention, it is possible to provide a magnesium alloy sheet material with improved strength by forming Al — Ca-based secondary phase particles in the magnesium alloy sheet material.
According to the method for manufacturing a magnesium alloy sheet material of one embodiment of the present invention, a magnesium alloy sheet material having excellent strength and formability can be provided by controlling the manufacturing process of a commercially available magnesium alloy. Therefore, IT can be applied to automobile parts or IT mobile devices in the future.
Drawings
Fig. 1 is a schematic sequence diagram of a method for manufacturing a magnesium alloy sheet material according to an embodiment of the present invention.
FIG. 2 is a Scanning Electron Microscope (SEM) photograph of the magnesium alloy sheet produced in example 1.
FIG. 3 is a SEM photograph of the magnesium alloy sheet material produced in comparative example 1.
Fig. 4 is a Secondary Electron microscope (Secondary Electron microscope) photograph of the magnesium alloy sheet manufactured in example 1.
Fig. 5 is a photograph showing the result of measuring the limit dome height (1 observing dome height) of the magnesium alloy sheet manufactured in example 1.
Fig. 6 shows the crystal orientation of the magnesium alloy sheet material produced in example 1, which was analyzed by an X-ray diffraction (XRD) analyzer.
Fig. 7 shows the results of analyzing the crystal orientation of the magnesium alloy sheet material produced in comparative example 1 by an XRD analyzer.
FIG. 8 is an Electron Back Scattering Diffraction (EBSD) photograph of the magnesium alloy sheet manufactured in example 1.
Fig. 9 shows the results of EBSD analysis of the surface corresponding to the reduction ratio in the skin pass rolling step.
Fig. 10 shows the integrated intensity of the (0001) plane in the examples and comparative examples of the present application.
Detailed Description
The terms first, second, third, and the like are used for describing a plurality of portions, components, regions, layers, and/or sections, but are not limited to the terms. These terms are only used to distinguish one element, component, region, layer or section from another element, component, region, layer or section. Thus, a first portion, first component, first region, first layer, or first section described below may represent a second portion, second component, second region, second layer, or second section without departing from the scope of the invention.
The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The singular as used herein also includes the plural as long as it does not define an obviously opposite meaning in a sentence. The term "comprising" as used in the specification is intended to specify the presence of particular features, regions, integers, steps, acts, elements and/or components, but does not exclude the presence or addition of other features, regions, integers, steps, acts, elements and/or components.
Where a portion is described as being "on" or "over" another portion, it can be directly on or over the other portion or there can be other portions between the two. Conversely, where a portion is described as being "on" or "over" another portion, there are no other portions between the two.
Although not specifically defined, all terms including technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. In general, terms defined in advance are additionally understood as having a sense of being consistent with the contents of the related art documents and the present disclosure, and are not to be construed as strange or particularly fundamental unless defined otherwise.
In addition,% represents weight% (wt%) unless otherwise specified.
Hereinafter, examples of the present invention will be described in detail so that those skilled in the art to which the present invention pertains can easily carry out the present invention. However, the present invention can be implemented in a plurality of different ways, and is not limited to the embodiments described herein.
The magnesium alloy sheet material according to one embodiment of the present invention contains 2.7 to 5 wt% of Al, 0.75 to 1 wt% of Zn, 0.1 to 1 wt% of Ca, 1 wt% or less of Mn (excluding 0 wt%), and the remaining wt% is composed of Mg and unavoidable impurities.
The reason why the numerical value of the component content in one embodiment of the present invention is limited will be described below.
First, aluminum (Al) improves mechanical physical properties of the magnesium alloy sheet material and improves castability of molten metal. When Al is excessively added, the castability may be rapidly deteriorated, and when Al is excessively added, the mechanical properties of the magnesium alloy sheet material may be deteriorated. Therefore, the content range of Al can be adjusted to the aforementioned range.
Zinc (Zn) improves the mechanical properties of the magnesium alloy sheet material. If Zn is excessively added, a large amount of surface defects and center segregation are generated, and the castability is rapidly deteriorated, and if Zn is excessively added, the mechanical properties of the magnesium alloy plate material are deteriorated. Therefore, the content range of Zn can be adjusted to the aforementioned range.
Calcium (Ca) imparts flame retardancy to the magnesium alloy sheet. When Ca is excessively added, the fluidity of the molten metal is reduced, the castability is deteriorated, and center segregation of the Al — Ca intermetallic substance composition is generated, whereby the formability of the magnesium alloy sheet material may be deteriorated. Therefore, the content range of Ca can be adjusted to the aforementioned range. More specifically, Ca may be included at 0.3 to 0.8 wt%.
Manganese (Mn) improves the mechanical properties of magnesium alloy sheets. When Mn is excessively added, problems may occur in that the heat release property is lowered and it is difficult to control the uniform distribution. Therefore, the content range of Mn can be adjusted to the aforementioned range.
A magnesium alloy sheet according to an embodiment of the present invention includes 20 to 25 wt% of Al, 5 to 10 wt% of Ca, 0.1 to 0.5 wt% of Mn, 0.5 to 1 wt% of Zn, and the remaining wt% of Al-Ca secondary phase particles including Mg. In general, when Al and Ca are added to magnesium to perform alloying, center segregation of an Al — Ca intermetallic compound is generated, and formability is significantly reduced. In contrast, the magnesium alloy sheet material according to an embodiment of the present invention can improve the formability by including Al — Ca secondary phase particles. Of secondary phase particles of Al-CaThe average particle size may be 0.01 to 4 μm. The moldability can be further improved within the above range. Further, the magnesium alloy sheet material has a thickness of 100 μm2May comprise 5 to 15 Al-Ca secondary phase particles. The formability of the magnesium alloy sheet material can be further improved by the Al-Ca secondary phase particles in the amount within the above range. In order to obtain the above-mentioned Al-Ca secondary phase particles, it is necessary to precisely adjust the composition ranges of Al, Zn, Mn and Ca, the temperature and time conditions at the time of the homogenizing heat treatment, the temperature and the reduction ratio at the time of warm rolling, and the like.
The magnesium alloy sheet material includes crystal grains, and the average grain size of the crystal grains may be 5 to 30 μm. The moldability can be further improved within the above range. In order to obtain the above-described particle size, it is necessary to precisely adjust the composition ranges of Al, Zn, Mn, and Ca, the temperature and time conditions for the homogenization heat treatment, the temperature and reduction ratio for the warm rolling, and the like.
In addition, the limit dome height (1 imaging dome height) of the magnesium alloy sheet material according to an embodiment of the present invention may be 7mm or more. More specifically above 8mm, and even more specifically between 8 and 10 mm.
In general, a limit dome height is used as an index for evaluating moldability (particularly compressibility) of a material, and an increase in the limit dome height indicates an improvement in moldability of the material.
The defined range is defined by an increase in the degree of grain orientation distribution within the magnesium alloy sheet material, which is a significantly higher limit dome height than commonly known magnesium alloy sheet materials.
In addition, the thickness of the magnesium alloy sheet material according to an embodiment of the present invention may be 0.4 to 3 mm.
Fig. 1 is a sequence diagram schematically illustrating a method for manufacturing a magnesium alloy sheet material according to an embodiment of the present invention. The sequence of the method for manufacturing the magnesium alloy sheet material of fig. 1 is only for illustrating the present invention, and the present invention is not limited thereto. Therefore, the method for manufacturing the magnesium alloy sheet material can be variously modified.
The method for manufacturing the magnesium alloy sheet material of one embodiment of the invention comprises the following steps: a cast member production step (S10) of producing a cast member by casting a molten metal containing 2.7 to 5 wt% of Al, 0.75 to 1 wt% of Zn, 0.1 to 1 wt% of Ca, and 1 wt% or less of Mn (excluding 0 wt%), with the remainder consisting of Mg and unavoidable impurities; a homogenization heat treatment step (S20) for performing homogenization heat treatment on the cast product; and a warm rolling step (S30) for warm rolling the homogenized and heat treated cast product. In addition, the manufacturing method of the magnesium alloy sheet material may further include other steps as needed.
First, in step (S10), a cast member is produced by casting a molten metal containing 2.7 to 5 wt% of Al, 0.75 to 1 wt% of Zn, Ca: 0.1 to 1 wt% and 1 wt% or less of Mn (excluding 0 wt%), and the remaining wt% consisting of Mg and inevitable impurities.
The reason for limiting the numerical value of each component is the same as that described above, and therefore, the repetitive description thereof will be omitted.
In this case, the casting manufacturing method may use die casting, strip casting, billet casting, centrifugal casting, bronze casting, sand casting, semi-continuous casting (Direct chill casting), or a method combining them. More specifically, a strip casting process may be utilized. However, the present invention is not limited thereto.
More specifically, in the casting manufacturing step, the rolling force may be 0.2 ton/mm2The above. And even more particularly at 1 ton/mm2The above. And even more particularly, from 1 to 1.5 tons/mm2The above.
The casting may be manufactured by casting. In this case, the cast member is subjected to a rolling force while being solidified, and in this case, the formability of the magnesium alloy sheet material can be improved by adjusting the rolling force to the above range. In step (S20), the casting continues to be subjected to the homogenizing heat treatment. At this time, as the heat treatment conditions, heat treatment may be performed at a temperature of 350 to 500 ℃ for 1 to 28 hours. More specifically, the homogenization heat treatment may be performed for 18 to 28 hours. When the temperature is too low, the homogenization treatment cannot be performed normally, and the homogenization treatment may occur as Mg17Al12Some beta-phase of (2) is not solid-dissolved in the base phase. At too high a temperature, a fire may occur due to the melting of some of the beta phase condensed in the casting or in the magnesium slabThe material creates voids. Therefore, the homogenization heat treatment can be performed within the aforementioned temperature range.
In step (S30), the casting after the homogenization heat treatment is warm-rolled. In this case, the warm rolling may be performed under a temperature condition of 150 to 350 ℃. At too low a temperature, problems of multiple edge cracks can occur. When the temperature is too high, it may cause a problem of being unsuitable for mass production. Therefore, warm rolling can be performed within the aforementioned temperature range.
The step of performing warm rolling (S30) may be performed a plurality of times, and the warm rolling may be performed at a reduction ratio of 10 to 30% each time. By performing warm rolling a plurality of times, the steel sheet can be rolled to a thin thickness of 0.4 mm.
More than one intermediate annealing step can be included between the multiple warm rolling. By further including the intermediate annealing step, the formability of the magnesium alloy sheet can be further improved. Specifically, the intermediate annealing step may be performed at a temperature of 300 to 500 ℃ for 1 to 10 hours. More specifically, it can be carried out at a temperature of 450 to 500 ℃. In the above range, the formability of the magnesium alloy sheet material can be further improved.
After the step of warm rolling (S30), a post heat treatment step may be further included. The formability of the magnesium alloy sheet can be further improved by further including a post heat treatment step. The step of performing the post heat treatment may be performed at 300 to 500 ℃ for 1 to 10 hours. In the above range, the formability of the magnesium alloy sheet material can be further improved.
The method for manufacturing the magnesium alloy sheet material of one embodiment of the invention comprises the following steps: a master alloy preparation step of preparing a master alloy including 2.7 wt% or more and 5 wt% or less of Al, 0.75 wt% or more and 1 wt% or less of Zn, 0.1 wt% or more and 0.7 wt% or less of Ca, more than 0 wt% and 1 wt% or less of Mn, and the balance of inevitable impurities and magnesium, with respect to 100 wt% of the whole; a casting manufacturing step of manufacturing a casting by casting the master alloy; a homogenization heat treatment step of performing homogenization heat treatment on the cast product; a rolled material manufacturing step of manufacturing a rolled material by rolling the cast material after the homogenization heat treatment; a post-heat treatment step of performing post-heat treatment on the rolled piece; and a magnesium alloy sheet manufacturing step of performing skin pass rolling on the rolled material after the post heat treatment to manufacture a magnesium alloy sheet.
First, in the step of preparing a master alloy including 2.7 wt% or more and 5 wt% or less of Al, 0.75 wt% or more and 1 wt% or less of Zn, 0.1 wt% or more and 0.7 wt% or less of Ca, more than 0 wt% and 1 wt% or less of Mn, and the balance of inevitable impurities and magnesium with respect to 100 wt% of the whole, the master alloy may be a commercially available AZ31 alloy, Al5083 alloy, or a combination thereof. However, the present invention is not limited thereto.
Next, a step of manufacturing a cast member by casting the master alloy may be performed.
More specifically, the molten metal may be prepared by dissolving the master alloy at a temperature range of 650 to 750 ℃. Thereafter, a cast member may be manufactured by casting the molten metal. At this time, the thickness of the casting may be 3 to 7 mm.
At this time, the casting manufacturing method may use die casting, strip casting, billet casting, centrifugal casting, bronze casting, sand casting, semi-continuous casting (Direct chill casting), or a combination thereof. More specifically, a strip casting process may be utilized. However, the present invention is not limited thereto.
More specifically, in the casting manufacturing step, the rolling force may be 0.2 ton/mm2The above. And even more particularly at 1 ton/mm2The above. And even more particularly, from 1 to 1.5 tons/mm2The above.
Thereafter, a step of homogenizing heat treatment of the casting may be performed.
More specifically, the homogenizing heat treatment step comprises: a primary heat treatment step at a temperature range of 300 ℃ to 400 ℃; and a secondary heat treatment step in a temperature range of 400 ℃ to 500 ℃. Even more specifically, one heat treatment step at a temperature range of 300 ℃ to 400 ℃ may be performed for 5 hours to 20 hours. In addition, the secondary heat treatment step at a temperature range of 400 ℃ to 500 ℃ may be performed for 5 hours to 20 hours.
By performing the heat treatment step once in the temperature range, the Mg-Al-Zn ternary wave abnormality generated at the casting step can be removed. When the ternary wave abnormality exists, the subsequent process may be adversely affected. Further, by performing the secondary heat treatment step in the above temperature range, the stress in the billet can be eliminated. Further, the recrystallization formation of the cast structure in the billet can be guided more actively.
Next, a step of rolling the cast product after the homogenization heat treatment to produce a rolled product may be performed.
The billet after heat treatment can be rolled to the thickness range of 0.4 to 3mm by 1 to 15 times of rolling. In addition, the rolling may be performed at 150 to 350 ℃.
More specifically, at a rolling temperature of less than 150 ℃, surface-induced cracks may be generated at the time of rolling, and at a temperature exceeding 350 ℃, may not be suitable for practical mass-production facilities. Thus, rolling can be performed at 150 ℃ to 350 ℃.
Next, a step of intermediate annealing the rolled material may be performed. When the rolling step is performed a plurality of times, the heat treatment may be performed at a temperature ranging from 300 ℃ to 550 ℃ for 1 hour to 15 hours in the interval between two rolling lines. For example, the steel sheet can be rolled to a final target thickness by performing intermediate annealing once after performing secondary rolling. As another example, rolling may be performed to a final target thickness by performing annealing once after performing rolling three times. More specifically, when the rolled casting is annealed in the temperature range, the stress generated by rolling can be eliminated. Therefore, rolling can be performed a plurality of times until the thickness of the target cast product becomes thick.
Finally, a step of skin pass rolling the rolled piece after the post heat treatment to manufacture a magnesium alloy sheet may be performed. More specifically, skin pass rolling, also called skin rolling or temper rolling, is cold rolling performed with light pressure to increase hardness by removing deformation marks generated in a cold-rolled steel sheet after heat treatment.
Thus, in one embodiment of the present invention, skin pass rolling may be performed once at a temperature ranging from 250 ℃ to 350 ℃. More specifically, the magnesium alloy sheet material produced by skin pass rolling can be obtained by rolling at a reduction ratio of 2 to 15%, and more specifically, at a reduction ratio of 2 to 6%, with respect to the thickness of the rolled material. More specifically, when rolling is performed under the above temperature and pressure conditions, the development of a (0001) texture, which is a weak basal texture, can be reduced, and hence formability can be ensured.
Further, the magnesium alloy plate material produced by performing a magnesium alloy plate material production step of subjecting the annealed rolled material to skin pass rolling to produce a magnesium alloy plate material can be obtained by rolling at a reduction ratio of 2 to 15% with respect to the thickness of the rolled billet. More specifically, it can be obtained by rolling at a reduction ratio of 2 to 6%.
When rolling at the reduction ratio, the strength can be improved by minimizing the variation in the strength of the integrated structure. More specifically, at a reduction ratio of 2 to 6%, the variation in strength of the integrated structure can be minimized, and the yield strength can be made 170 to 300 MPa. Additionally, the Limit Dome Height (LDH) value may be 8 to 9 mm.
However, at a reduction of 2 to 15%, the yield strength can be made 250 to 280MPa, but the aggregate structure is more or less developed and the ultimate dome height (LDH) value can be made 7 to 8 mm. This is because, as shown in fig. 9, a hardening phenomenon may occur due to double twisting or dislocation when rolling is performed at a reduction ratio of 6 to 15%. More specifically, when the reduction ratio is 2 to 6%, the area% of the twinned structure may be 5% or less with respect to 100 area% of the entire magnesium alloy sheet material. More specifically, the area of the twinned structure may be 5% to 20% with respect to 100% by area of the entire magnesium alloy sheet material when rolled at a reduction ratio of 6 to 15%. In the structure photograph disclosed in fig. 9, black indicates a twinned structure, and as described above, formability can be improved while maintaining the strength of the magnesium alloy sheet material due to twinning and dislocation.
Therefore, when rolling is performed at a reduction ratio of more than 15%, the (0001) plane texture develops again, and formability may be reduced. This may be the same phenomenon that occurs due to a low temperature range at the time of rolling. Therefore, skin pass rolling can be performed under the temperature range and reduction ratio conditions of one embodiment of the present invention.
The above-mentioned Limit Dome Height (LDH) is an index for evaluating the formability, particularly the punching formability, of the sheet material, and the formability can be measured by measuring the Height at which the test piece is deformed by being deformed.
More specifically, the Limit Dome Height (LDH) of an embodiment of the invention is a height measured by: after the outer periphery of a test piece 50mm in diameter is fixed at a pressure of 10KN, the test piece is deformed at a speed of 5 to 10 mm/min at room temperature by a spherical punch 20mm in diameter, and the distance moved by the punch until the disk-shaped test piece is broken, that is, the height of the deformed test piece, is measured.
Preferred examples and comparative examples of the present invention are described below. However, the following examples are merely preferred examples of the present invention, and the present invention is not limited to the following examples.
Example 1
By passing the molten metal at a rolling force of 1.2 ton/mm2The magnesium casting was manufactured between the two chill rolls of (1), wherein the molten metal included 3.0 wt.% of Al, 0.8 wt.% of Zn, 0.6 wt.% of Ca, and 0.5 wt.% of Mn, and the remaining wt.% was composed of Mg and unavoidable impurities.
A magnesium casting was subjected to a homogenization heat treatment at 400 ℃ for 24 hours, and then to a warm rolling at a temperature of 250 ℃ and a reduction ratio of 15%, and then to an intermediate annealing at 450 ℃ for 1 hour, and then to a warm rolling again at a temperature of 250 ℃ and a reduction ratio of 15%, thereby producing a magnesium alloy sheet having a final thickness of 0.7 mm.
Comparative example 1
A magnesium alloy sheet material was produced by performing the same treatment as in example 1, except that the magnesium alloy sheet material included 3.0 wt% of Al and 0.8 wt% of Zn.
Experimental example 1: observation of microstructure constituting magnesium alloy sheet Material
Fig. 2 and 3 show Scanning Electron Microscope (SEM) photographs of the magnesium alloy sheet materials produced in example 1 and comparative example 1, respectively.
The following can be confirmed: in the case of example 1 (fig. 2), center segregation is hardly generated in the magnesium alloy sheet material, and in contrast, in the case of comparative example 1 (fig. 3), center segregation is generated in a large amount. Such center segregation is a factor of remarkably lowering the formability of the magnesium alloy sheet material.
Fig. 4 shows a Secondary Electron microscope (Secondary Electron microscope) photograph of the magnesium alloy sheet produced in example 1.
The white portion of FIG. 4 is Al-Ca secondary phase particles. The white spot portion was analyzed for results including 65.62 wt.% Mg, 24.61 wt.% Al, 8.75 wt.% Ca, 0.36 wt.% Mn, and 0.66 wt.% Zn.
Experimental example 2: measurement of limit dome height of magnesium alloy sheet
The measurement of the limit dome height is performed by: the magnesium alloy plate materials of examples and comparative examples were inserted between an upper steel form and a lower steel form, and the outer peripheral portions of the test pieces were fixed at a pressure of 5kN, and a known press oil was used as a lubricating oil. Then, the test pieces were deformed at a speed of 5 to 10 mm/min using a spherical punch having a diameter of 30mm, and the punch was inserted until each test piece was broken, and the deformed height of each test piece was measured when such breakage occurred.
Fig. 5 is a photograph of the result of measuring the limit dome height on the magnesium alloy sheet manufactured in example 1.
Experimental example 3: grain orientation analysis
The crystal orientations of the crystal grains of the magnesium alloy sheet materials manufactured in example 1 and comparative example 1 were confirmed by an XRD analyzer, and are shown in fig. 6 and 7, respectively.
In the case of example 1 (fig. 6), it was confirmed that the contour line was diffused widely and the crystal orientation of the crystal grains in the plate material existed in a wide and diversified manner. Therefore, it was confirmed that the moldability of example 1 was excellent. In contrast, in the case of comparative example 1 (fig. 7), it was confirmed that (0001) peak was crowded together.
An EBSD photograph of example 1 was taken as shown in fig. 8. As shown in < b >, it was found that the distribution of the misorientation (misorientation) values of the respective crystal grains was uniform, and it was confirmed that the respective crystal grains had various crystal orientations.
Example 2
A master alloy including 3% of Al, 1% of Zn, 1% of Ca, and 0.3% of Mn, with the remainder consisting of magnesium and inevitable impurities was prepared.
A cast article is produced by casting the master alloy. The casting was subjected to primary homogenizing heat treatment at 350 ℃ for 10 hours. And subjecting the cast product after the primary homogenizing heat treatment to a secondary homogenizing heat treatment at 450 ℃ for 10 hours. A rolled material is produced by rolling the homogenized and heat treated cast material. Subsequently, the rolled material was post-heat treated at 400 ℃ for 10 hours.
Finally, the rolled material after the post heat treatment was skin-pass rolled at a temperature and a reduction ratio shown in table 1 below to produce a magnesium plate.
Experimental example 4: skin pass rolling reduction and temperature-corresponding mechanical property comparison experiment
[ TABLE 1 ]
As shown in table 1, it is understood that the yield strength is improved so that the formability is not largely changed as a result of skin pass rolling of a magnesium alloy having the same composition and composition. More specifically, the formability can be compared by the values of the elongation and the limit dome height.
Further, formability is ensured by minimizing the variation in the collective strength as shown in fig. 10 of the present application.
Fig. 10 shows the integrated intensity of the (0001) plane in the examples and comparative examples of the present application.
As shown in fig. 10, in comparative examples 2a and 2c, as a result of a large change in strength of the integrated structure, it is understood that the yield strength is increased as shown in table 1. However, it is known that the elongation is drastically reduced and the moldability is more or less reduced.
Therefore, as shown in table 1 and fig. 10 of the present application, it was confirmed that the present application can minimize the strength variation of the aggregate structure and ensure the formability.
Example 3
A magnesium alloy sheet material was produced under conditions different from those shown in table 2 below, as compared with example 1. As a result, the mechanical properties of the magnesium alloy sheet material produced in example 3 are shown in table 3 below.
[ TABLE 2 ]
[ TABLE 3 ]
As a result, in the case of comparative examples 3a to 3d which did not satisfy the conditions of the homogenizing annealing time, the rolling temperature, and the intermediate annealing temperature, it was confirmed that the formability was inferior to that of the examples of the present application. Further, it is found that the yield strength is inferior to that of the examples of the present application. In comparative example 3c, the crystal grain size was 40 μm, and the moldability was relatively excellent compared to other comparative examples, but the level was inferior to that of the examples of the present application.
The present invention is not limited to these embodiments and can be produced in various ways, and those skilled in the art to which the present invention pertains will understand that the present invention can be implemented in other specific ways without changing the technical idea or essential features of the present invention. It is to be understood, therefore, that the embodiments described above are intended in all respects to be illustrative rather than restrictive.
Claims (5)
1. A magnesium alloy sheet material is characterized in that,
contains 2.7 to 5% by weight of Al, 0.75 to 1% by weight of Zn, 0.1 to 1% by weight of Ca and 1% by weight or less and more than 0% by weight of Mn, with the remainder consisting of Mg and unavoidable impurities,
wherein the area% of the twin structure is 5% or more and 20% or less with respect to 100 area% of the magnesium alloy sheet material,
wherein the magnesium alloy sheet material has a maximum collective strength based on a (0001) plane of 1 to 4,
wherein the magnesium alloy sheet material has a yield strength of 170 to 300MPa, an
Wherein the limit dome height of the magnesium alloy sheet material is 7mm or more.
2. A method for manufacturing a magnesium alloy sheet as claimed in claim 1, comprising
A master alloy preparation step of preparing a master alloy including, with respect to 100 wt% of the entire alloy, 2.7 wt% or more and 5 wt% or less of Al, 0.75 wt% or more and 1 wt% or less of Zn, 0.1 wt% or more and 1 wt% or less of Ca, more than 0 wt% and 1 wt% or less of Mn, and the balance being unavoidable impurities and magnesium;
a casting manufacturing step of manufacturing a casting by casting the master alloy;
a homogenization heat treatment step of performing homogenization heat treatment on the cast product;
a rolled material manufacturing step of warm-rolling the homogenized and heat-treated cast material to manufacture a rolled material;
a post-heat treatment step of performing post-heat treatment on the rolled piece; and
a magnesium alloy sheet manufacturing step of performing skin pass rolling on the rolled material after the post heat treatment to manufacture a magnesium alloy sheet,
wherein in the step of manufacturing a magnesium alloy sheet by skin pass rolling of the rolled material after post heat treatment, the manufactured magnesium alloy sheet is rolled at a reduction ratio of 6 to 15% with respect to the thickness of the rolled material, and
wherein the step of subjecting the cast member to a homogenizing heat treatment comprises a primary heat treatment step and a secondary heat treatment step.
3. The method of manufacturing a magnesium alloy sheet according to claim 2,
wherein the step of homogenizing heat treating the casting comprises:
a primary heat treatment step at a temperature range of 300 ℃ to 400 ℃; and
a secondary heat treatment step at a temperature range of 400 ℃ to 500 ℃,
wherein said one heat treatment step of a temperature interval of 300 ℃ to 400 ℃ is carried out for 5 hours to 20 hours,
wherein the secondary heat treatment step is carried out at a temperature ranging from 400 ℃ to 500 ℃ for 5 hours to 20 hours.
4. The method of manufacturing a magnesium alloy sheet according to claim 2,
wherein in the step of manufacturing a magnesium alloy sheet by skin pass rolling of the rolled material after post heat treatment, the skin pass rolling is performed at a temperature ranging from 250 ℃ to 350 ℃.
5. The method of manufacturing a magnesium alloy sheet according to claim 2,
wherein the rolled piece is annealed for 1 to 15 hours in a post heat treatment step by subjecting the rolled piece.
Applications Claiming Priority (5)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| KR1020150185017A KR20170075407A (en) | 2015-12-23 | 2015-12-23 | Magnesium alloy sheet, method for manufacturing the same |
| KR10-2015-0185017 | 2015-12-23 | ||
| KR10-2015-0186295 | 2015-12-24 | ||
| KR1020150186295A KR101751521B1 (en) | 2015-12-24 | 2015-12-24 | Method of manufacturing magnesium alloy sheet |
| PCT/KR2016/015228 WO2017111550A1 (en) | 2015-12-23 | 2016-12-23 | Magnesium alloy sheet material and manufacturing method therefor |
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| Publication Number | Publication Date |
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| CN108472699A CN108472699A (en) | 2018-08-31 |
| CN108472699B true CN108472699B (en) | 2021-12-28 |
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| US (1) | US20190093200A1 (en) |
| EP (1) | EP3395458B1 (en) |
| JP (1) | JP6758383B2 (en) |
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| KR20190000676A (en) * | 2017-06-23 | 2019-01-03 | 주식회사 포스코 | Magnesium alloy sheet and manufacturing for the same |
| KR102043786B1 (en) * | 2017-12-26 | 2019-11-12 | 주식회사 포스코 | Magnesium alloy sheet and method for manufacturing the same |
| KR102043287B1 (en) * | 2017-12-26 | 2019-11-11 | 주식회사 포스코 | Magnesium alloy sheet and method for manufacturing the same |
| CN108796327B (en) * | 2018-06-28 | 2020-08-28 | 郑州大学 | High-plasticity low-anisotropy deformed magnesium alloy plate and preparation method thereof |
| KR102239185B1 (en) * | 2018-12-18 | 2021-04-12 | 주식회사 포스코 | Manufacturing method of magnesium alloy plate having excellent formability and magnesium alloy plate using thereof |
| US20220275477A1 (en) * | 2019-08-26 | 2022-09-01 | Ohio State Innovation Foundation | Magnesium alloy based objects and methods of making and use thereof |
| CN113005347B (en) * | 2021-02-25 | 2021-10-08 | 吉林大学 | High-plasticity Mg-Al-Ca magnesium alloy and preparation method thereof |
| CN113416873B (en) * | 2021-06-28 | 2023-01-20 | 晋中学院 | Rare earth magnesium alloy plate with high electromagnetic shielding effect and preparation method thereof |
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| JP2009007606A (en) * | 2007-06-27 | 2009-01-15 | Mitsubishi Alum Co Ltd | Magnesium alloy sheet material having excellent corrosion resistance and surface treatability, and method for producing the same |
| JP2010229467A (en) * | 2009-03-26 | 2010-10-14 | Hitachi Metals Ltd | Method of producing magnesium alloy thin plate |
| KR101078308B1 (en) * | 2008-05-19 | 2011-10-31 | 포항공과대학교 산학협력단 | Magnesium alloy panel having high strength and manufacturing method for the same |
| KR101481909B1 (en) * | 2013-08-08 | 2015-01-13 | 주식회사 포스코 | Manufacturing method of magnesium alloy |
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| JP2010156007A (en) * | 2008-12-26 | 2010-07-15 | Mitsubishi Alum Co Ltd | Magnesium-alloy sheet excellent in corrosion resistance and surface treatability, and method for producing the same |
| JP5424391B2 (en) * | 2009-09-30 | 2014-02-26 | 国立大学法人長岡技術科学大学 | Magnesium alloy rolled material and method for producing the same |
| JP5590660B2 (en) * | 2010-03-01 | 2014-09-17 | 独立行政法人産業技術総合研究所 | Magnesium alloy sheet with improved cold formability and in-plane anisotropy and method for producing the same |
| JP5660525B2 (en) * | 2010-03-05 | 2015-01-28 | 独立行政法人産業技術総合研究所 | General-purpose magnesium alloy sheet that exhibits formability similar to that of aluminum alloy and method for producing the same |
| KR101626820B1 (en) * | 2013-12-05 | 2016-06-02 | 주식회사 포스코 | magnesium-alloy plate and manufacturing method of it |
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- 2016-12-23 CN CN201680075821.9A patent/CN108472699B/en active Active
- 2016-12-23 WO PCT/KR2016/015228 patent/WO2017111550A1/en active Application Filing
- 2016-12-23 US US16/065,562 patent/US20190093200A1/en not_active Abandoned
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Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2009007606A (en) * | 2007-06-27 | 2009-01-15 | Mitsubishi Alum Co Ltd | Magnesium alloy sheet material having excellent corrosion resistance and surface treatability, and method for producing the same |
| KR101078308B1 (en) * | 2008-05-19 | 2011-10-31 | 포항공과대학교 산학협력단 | Magnesium alloy panel having high strength and manufacturing method for the same |
| JP2010229467A (en) * | 2009-03-26 | 2010-10-14 | Hitachi Metals Ltd | Method of producing magnesium alloy thin plate |
| KR101481909B1 (en) * | 2013-08-08 | 2015-01-13 | 주식회사 포스코 | Manufacturing method of magnesium alloy |
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| EP3395458B1 (en) | 2021-08-18 |
| JP2019504207A (en) | 2019-02-14 |
| CN108472699A (en) | 2018-08-31 |
| EP3395458A1 (en) | 2018-10-31 |
| WO2017111550A1 (en) | 2017-06-29 |
| US20190093200A1 (en) | 2019-03-28 |
| EP3395458A4 (en) | 2018-10-31 |
| WO2017111550A8 (en) | 2017-09-28 |
| JP6758383B2 (en) | 2020-09-23 |
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