JP4189687B2 - Magnesium alloy material - Google Patents

Description

  The present invention relates to a magnesium alloy material made of a magnesium alloy. In particular, it relates to a magnesium alloy material having high strength and excellent corrosion resistance.

  Magnesium alloys have a small specific gravity and are attracting attention as lightweight materials. However, in general, magnesium and magnesium alloys have low corrosion resistance. Therefore, when various structural materials are formed from magnesium alloys, countermeasures against corrosion are necessary. One countermeasure is to adjust the alloy composition. For example, in recent years, it has been studied to reduce Fe, Ni, Cu, and the like, which are metals that lower corrosion resistance. Further, a high Al magnesium alloy such as AZ91 containing about 9% by mass of Al has an effect of improving the corrosion resistance by adding Al. Therefore, such a structural material made of a high Al magnesium alloy can be used as it is under a specific environment such as in the engine room of an automobile.

  However, it is not a special environment such as in the engine room, but is used for transportation / movement means such as automobiles and bicycles that are used in environments that are exposed to the normal atmosphere, wind and rain, or in direct contact with the human body. Even in the case of forming an exterior member or an exterior member of a home appliance such as a personal computer using a magnesium alloy with the above alloy composition adjusted, it is difficult to withstand use. Therefore, conventionally, surface treatment such as formation of a film has been performed to improve the corrosion resistance (refer to the conventional technology in Patent Document 1). However, if the surface-treated structural material falls and wrinkles occur, and the film is peeled off for some reason during use of the structural material, and the magnesium alloy base material is exposed, corrosion will occur from the exposed portion. It will progress. Therefore, it is desired to improve the corrosion resistance of the magnesium alloy itself.

  Patent Documents 1 and 2 disclose that corrosion resistance is improved by containing rare earth elements (RE) such as Y and Ce. Patent Document 3 discloses that the corrosion resistance is improved by using a structure of a magnesium alloy as a structure having an amorphous phase. On the other hand, Patent Document 4 discloses that Ca, a rare earth element, and Sn are contained to improve heat resistance.

JP-A-5-117798 JP 2003-64438 A JP 2002-249801 A JP 2005-68550 A

  However, the magnesium alloy materials described in Patent Documents 1, 2, and 4 are cast materials obtained by die casting or injection casting, and can be used only in a very limited region because of low strength. Further, these patent documents do not discuss anything about increasing the strength. Here, when the cast material is subjected to plastic working such as extrusion, rolling, and drawing, the obtained plastic work material generally tends to have higher strength than the cast material. Therefore, it is conceivable that the casting materials described in Patent Documents 1, 2, and 4 are subjected to plastic working in order to increase the strength. However, these cast materials contain a rare earth element for improving corrosion resistance, and are not suitable for plastic working.

  Further, in casting such as die casting or injection casting, it is difficult to obtain a long plate-like material, linear material, pipe, or the like. Furthermore, the casting materials described in Patent Documents 1, 2, and 4 containing rare earth elements such as Ce not only impair the lightness, but the rare earth elements are generally expensive, resulting in an increase in manufacturing cost.

  On the other hand, the magnesium alloy material described in Patent Document 3 is obtained by a special production method such as sintering powder having an amorphous phase, and compared with that obtained by a general production method such as casting. Inferior in productivity. Also in the case of sintering, it is difficult to obtain a long plate-like material, a linear material, a pipe, and the like as in the above-described die casting.

  The present invention has been made in view of the above circumstances, and a main object thereof is to provide a magnesium alloy material having high strength and excellent corrosion resistance. Another object of the present invention is to provide a magnesium alloy material that is inexpensive and can be easily manufactured.

  The magnesium alloy material of the present invention aims to improve both corrosion resistance and strength by adding a specific amount of Sn and performing plastic working. As a specific configuration, the magnesium alloy material of the present invention is characterized in that it contains 0.1 to 10.0% by mass of Sn, the balance is made of Mg and inevitable impurities, and is subjected to plastic working.

  Conventionally, Sn has not been studied as an element for improving the corrosion resistance of the magnesium alloy itself, but as a result of the study by the present inventors, it has been found that Sn contributes to the improvement of the corrosion resistance of the magnesium alloy itself. In particular, it has also been found that a plastic work material made of a magnesium alloy containing Sn is superior in corrosion resistance. Therefore, in the present invention, Sn is contained. As described above, the alloy material of the present invention is a plastic working material obtained by subjecting a cast material to plastic working. First, the alloy material of the present invention can drastically improve the strength by using a plastic working material instead of a cast material. Specifically, for example, the tensile strength can be set to 270 MPa or more. In addition, the alloy material of the present invention is subjected to plastic working, so that the alloy structure becomes finer than that of the cast material, and the corrosion resistance can be improved by this refinement. In particular, the alloy material of the present invention contains Sn as an element that contributes to the improvement of corrosion resistance without reducing the plastic workability. As described above, the alloy material of the present invention realizes improvement in strength and improvement in corrosion resistance by plastic working and addition of Sn. Therefore, the alloy material of the present invention exhibits excellent corrosion resistance even in an environment where it is in contact with the human body, in an environment exposed to the atmosphere or wind and rain, and has mechanical properties as required for structural materials. Since it is sufficiently prepared, it can be used for structural materials in various fields. Hereinafter, the configuration of the present invention will be described in more detail.

  The alloy material of the present invention is composed of a magnesium alloy composed of an additive element, Mg, and inevitable impurities. The additive element requires Sn. In addition to Sn, at least one element selected from the group consisting of Al, Si, Ca, Zn, and Mn may be used as the additive element. Preferably, Sn and Al are added elements, and more preferably, Sn, Al, Zn, and Mn are added elements. The total content of these additive elements is preferably 20% by mass or less. If the additive element exceeds 20% by mass, it may cause cracks during casting. Specific examples of the composition of the alloy material of the present invention include the following compositions I to X.

I. Sn: 0.1% by mass or more and 10.0% by mass or less, with the balance being Mg and inevitable impurities II. Sn: 0.1% by mass or more and 10.0% by mass or less, Al: more than 0% by mass and less than 5% by mass, with the balance being Mg and inevitable impurities III. Sn: 0.1% by mass or more and 10.0% by mass or less and Al: 5% by mass or more and 12% by mass or less, with the balance being Mg and inevitable impurities IV. Sn: 0.1% by mass to 10.0% by mass, Al: 1% by mass to 12% by mass, Si: 0.1% by mass to 2% by mass, Ca: 0.01% by mass to 3% by mass % Or less, Zn: 0.1 mass% or more and 2 mass% or less, Mn: One or more elements selected from the group consisting of 0.1 mass% or more and 2 mass% or less, with the balance being Mg and inevitable Impurities V. Sn: 0.1% by mass or more and 10.0% by mass or less, Al: more than 0% by mass and less than 5% by mass, Si: 0.1% by mass or more and 2% by mass or less, Ca: 0.01% by mass or more 3 1 mass% or less, Zn: 0.1 mass% or more and 2 mass% or less, Mn: One or more elements selected from the group consisting of 0.1 mass% or more and 2 mass% or less, with the balance being Mg and inevitable Impurities VI. Sn: 0.1% by mass to 10.0% by mass, Al: 5% by mass to 12% by mass, Si: 0.1% by mass to 2% by mass, Ca: 0.01% by mass to 3% 1 mass% or less, Zn: 0.1 mass% or more and 2 mass% or less, Mn: One or more elements selected from the group consisting of 0.1 mass% or more and 2 mass% or less, with the balance being Mg and inevitable Impurities VII. Sn: 0.1% by mass or more and 10.0% by mass or less, Al: more than 0% by mass and less than 5% by mass, Zn: 0.1% by mass or more and 2% by mass or less, Mn: 0.1% by mass or more 2 mass% or less, with the balance being Mg and inevitable impurities VIII. Sn: 0.1% by mass or more and 10.0% by mass or less, Al: more than 0% by mass and less than 5% by mass, Zn: 0.1% by mass or more and 2% by mass or less, Mn: 0.1% by mass or more 2 mass% or less, Si: 0.1 mass% or more and 2 mass% or less, and Ca: 0.01 mass% or more and 3 mass% or less of the elements, with the balance being Mg and inevitable impurities IX. Sn: 0.1% by mass or more and 10.0% by mass or less, Al: 5% by mass or more and 12% by mass or less, Zn: 0.1% by mass or more and 2% by mass or less, Mn: 0.1% by mass or more 2% by mass or less, with the balance being Mg and inevitable impurities X. Sn: 0.1% by mass or more and 10.0% by mass or less, Al: 5% by mass or more and 12% by mass or less, Zn: 0.1% by mass or more and 2% by mass or less, Mn: 0.1% by mass or more 2% by mass or less, Si: 0.1% by mass or more and 2% by mass or less and Ca: 0.01% by mass or more and 3% by mass or less, with the balance being Mg and inevitable impurities

  Sn is an element necessary for improving the corrosion resistance. If the content is less than 0.1% by mass, the effect cannot be obtained. As the Sn content increases, the corrosion resistance tends to be improved. However, if the Sn content is too large, weight reduction is inhibited, so the upper limit of the Sn content is 10.0% by mass. A more preferable content of Sn is 0.5% by mass or more and 6% by mass or less. In addition, when making an additive element only Sn, the upper limit of content can be 14 mass%.

  Al strengthens the magnesium alloy, improves the mechanical properties, and contributes to corrosion resistance. Therefore, it is preferable to add Al to the magnesium alloy in addition to Sn. In order to acquire the said effect, it is preferable to make content of Al more than 0-12 mass%, and it is preferable to set it as 1-12 mass% especially. However, Al tends to reduce toughness when added in excess. Therefore, when higher strength than toughness is desired, the Al content is preferably 5% by mass or more and 12% by mass or less. When higher toughness than strength is desired, the Al content is 5% by mass. It is preferable to make it less than%.

In addition to Al, a magnesium alloy containing one or more elements selected from Mn: 0.1 to 2%, Zn: 0.1 to 2%, and Si: 0.1 to 2% by mass% You may utilize for an invention alloy material. That is, for the formation of the alloy material of the present invention, magnesium alloys used for die casting, casting, and extension, specifically, any of AM-based alloys, AZ-based alloys, and AS-based alloys in the ASTM standard are used. Can be used. Among these alloys, a magnesium alloy containing any one of the alloys as a main component and added with Sn in the specific range may be used. For example, a magnesium alloy containing an AZ alloy containing Al, Zn, or Mn as a main component, specifically, an alloy such as AZ31, AZ61, or AZ91 may be used as a main component. When these alloys are used, particularly when a magnesium alloy containing Si is used, if the cooling at the time of casting is cooling with a slow cooling rate such as natural cooling, the obtained cast material has a coarse crystallized product. (For example, Mg ₂ Si) is crystallized. Such coarse crystallized products hinder plastic workability. Therefore, when manufacturing this invention alloy material using the said alloy, it is preferable that the cooling at the time of casting cools as rapidly as possible and makes a crystallized substance fine. Further, when Ca is added as an additive element, there is an effect of suppressing the growth of crystal grains at the time of recrystallization by plastic working or at the time of recrystallization by heat treatment after plastic working described later. In order to obtain this grain growth inhibiting effect, the Ca content is preferably 0.01% by mass or more. The above effect increases as the content of Ca increases. However, as the content increases, coarse intermetallic compounds such as Mg-Ca intermetallic compounds and Al-Ca intermetallic compounds (when the additive element contains Al) are used. Easily produced in alloys. The presence of this coarse intermetallic compound causes a decrease in the ductility of the alloy, thereby reducing the plastic workability of the alloy. Therefore, the upper limit of the Ca content is 3% by mass. Examples of impurities inevitably contained in addition to these additive elements and Mg as a main component include Fe, Cu, and Ni.

  The alloy material of the present invention is manufactured by first preparing an alloy having the above composition, melting and casting the alloy, and subjecting the obtained cast material to plastic working. This plastic working is preferably performed after a heat treatment (solution treatment) rather than the cast material as it is. Examples of the heat treatment conditions include a temperature: 380 to 420 ° C. and a holding time: 2 to 20 hours.

  Various processes such as extrusion, rolling, drawing (drawing), forging, pressing, bending, and swaging can be applied as the plastic working, and there is no particular limitation. Therefore, the alloy material of the present invention can be various plastic working materials such as extruded materials, rolled materials, solid or hollow drawn materials, and forged materials. The plastic working may be appropriately selected so as to have a desired shape and form. For example, when the alloy material of the present invention is a plate-like material, rolling or extrusion may be performed, and when the alloy material of the present invention is a linear material or pipe, a drawing process may be performed. Rolling and drawing are suitable for obtaining long materials.

  Each of the above processes may be performed only once or may be performed a plurality of times (multi-pass), but the deformation is performed so that the total cross-section reduction rate is 10% or more. Preferably, it is performed so as to be 30% or more. Moreover, it is preferable that the plastic processing initially performed on the cast material is hot processing performed by heating the cast material to a predetermined temperature, and the subsequent plastic processing is cold performed without particularly heating the workpiece. It is good also as processing, and it is good also as hot processing performed by heating a workpiece to predetermined temperature. In the case of hot working, the heating temperature is preferably 200 ° C to 400 ° C. When the plastic working is performed a plurality of times, an intermediate heat treatment may be performed once or a plurality of times to recover the strain introduced with the plastic working. Examples of the intermediate heat treatment conditions include heating temperature: 100 ° C. or higher (preferably 150 ° C. or higher) 400 ° C. or lower, and holding time: about 5 to 20 minutes.

  The plastic processing applied to the cast material may be two or more different types of processing. That is, primary processing may be performed on the cast material, and secondary processing different from the primary processing may be performed on the obtained primary processing material. At this time, the primary processing may be hot processing, and the secondary processing may be either cold processing or hot processing. When the primary processing and the secondary processing are separately performed and the secondary processing or lower is performed hot, the heating temperature of the processing after the secondary processing may be 200 ° C. or lower. For example, when hot rolling is performed in the primary process and hot drawing is performed in the secondary process, the heating temperature of the workpiece during the drawing process may be 50 ° C. or more and 200 ° C. or less. Plastic processing such as drawing, forging, pressing, bending, swaging, and the like is preferable because it is easy to process when applied to an extruded material obtained by extruding a cast material or a rolled material obtained by rolling a cast material. The secondary processing such as drawing may be performed after heat treatment (solution treatment) is performed on the extruded material or the rolled material. Examples of the heat treatment conditions include a temperature: 380 to 420 ° C. and a holding time of 1 to 10 hours.

  Further, forging, pressing, bending, and swaging are preferably performed on a drawn material from which an extruded material or a rolled material has been drawn, so that tertiary processing such as forging can be easily performed. The tertiary processing such as forging may be performed after appropriately performing heat treatment on the drawn material. As heat treatment conditions, temperature: 100 to 300 ° C., preferably 150 to 300 ° C., holding time: about 5 to 20 minutes can be mentioned. By this heat treatment, strain associated with the drawing process can be removed, recrystallization can be promoted to make the crystal grains fine, and plastic workability can be improved.

  The above drawing process is preferably performed using a wire drawing die or a roller die. In particular, when a wire drawing die is used, a difference in diameter difference (difference between the maximum value of the diameter and the minimum value of the diameter in the same cross section of the wire). A solid or hollow linear material that is small in size and excellent in dimensional accuracy can be easily manufactured. A linear material having a desired size can be obtained by performing drawing processing over a plurality of passes using dies having different sizes (diameters) of die holes in multiple stages. The drawing process conditions are as follows: temperature increase rate to the processing temperature: 1 ° C./sec to 100 ° C./sec, processing temperature: 50 ° C. to 300 ° C. (preferably 100 ° C. to 200 ° C.), processing degree: 10% / Examples include pass (solid), 5% or more / pass (hollow), linear speed: 1 m / min or more, and cooling rate after drawing: 0.1 ° C./sec or more. The higher the processing temperature, the higher the drawing workability of the workpiece, and for example, processing with a large processing degree becomes possible. The drawing process may be performed at room temperature without heating as described above. In this case, the degree of processing per pass may be reduced (although depending on the alloy composition, approximately 15% or less, preferably 10% or less), or pre-heat treatment may be performed before drawing. Examples of the pre-heat treatment condition include heating temperature: 200 ° C. or higher and 450 ° C. or lower (preferably 250 ° C. or higher and 400 ° C. or lower), and holding time: about 15 to 60 minutes. The drawing process is preferably performed using a lubricant. The drawing process conditions may be the same as the conditions described in Japanese Patent Application Laid-Open Nos. 2003-293069 and 2004-232075.

  Furthermore, the following specific heat treatment may be performed after the final plastic working. By performing the heat treatment, further refinement by recrystallization and removal of strain associated with plastic working can be performed. Moreover, the aging by precipitation can be accelerated | stimulated by heat-processing. The alloy material of the present invention that has been subjected to the above-described plastic working has a fine structure in which a compound (precipitate) containing crystal grains and Sn is refined, and the following specific heat treatment is performed after the final plastic working as described above. By applying, further refinement of the crystal grains and further refinement / dispersion of the precipitates can be achieved. Examples of the heat treatment conditions include temperature: 150 to 350 ° C., preferably 200 to 300 ° C., holding time: 15 minutes to 20 hours. Although heat treatment is performed at the above temperature for a holding time of about 15 minutes to about 60 minutes, it is effective in refining and removing strain, but depending on the amount of Al and Sn contained in the alloy material, it takes a longer time. (About 1 to 20 hours) is preferable, and may be appropriately adjusted according to the amount of Al or the amount of Sn. The cast material has a relatively large average crystal grain size of 100 μm or more, whereas the alloy material according to the present invention, which is a combination of the plastic processing and appropriate heat treatment, has a fine crystal structure with an average crystal grain size of 30 μm or less. Have In addition, in the cast material, the average diameter of the precipitate containing Sn is relatively large as 20 μm or more, whereas the alloy material of the present invention, which is obtained by combining the plastic working and the appropriate heat treatment, has the average diameter of the precipitate. Is an alloy structure in which these fine grains are uniformly dispersed. The alloy material of the present invention having an alloy structure composed of such fine crystal grains and dispersed with fine Sn-containing precipitates is present per grain boundary unit area by increasing the grain boundary area as the whole alloy structure. Since there are few impurities (for example, Fe, Ni, Cu, etc.) and Sn exists uniformly in the structure, it can have high corrosion resistance.

  The average crystal grain size and the average diameter of the precipitate containing Sn are measured as follows. First, in the cross section of the alloy, a region having a depth of 100 μm from the surface to the center is the surface layer portion, and when the distance from the surface to the center is r, the region at the position of r / 2 is the central portion, and the vicinity of the center Is observed in the center using an optical microscope or the like at any one or more locations (magnification: 200 to 1000 times) and exists in a specific area (for example, 100 to 300 μm × 100 to 300 μm). The crystal grain size and the size of the precipitate are measured. Measurement of the particle size and size may be performed by a cutting method (see JIS H 0501). Such measurement is performed on two or more cross sections. And let the average of the particle diameter of all the obtained crystal grains be an average crystal grain diameter, and let the average of the magnitude | size of all the obtained precipitates be the average diameter of a precipitate. The crystal grain size may be measured using a transmission electron microscope (TEM) or a backscattered electron diffraction method (EBSP).

  By applying plastic working as described above, the alloy material of the present invention has excellent strength. In particular, by appropriately containing Al, it has excellent strength such as a tensile strength of 270 MPa or more. Moreover, it has the outstanding toughness of elongation 7% or more by containing Al suitably. More specifically, the alloy material of the present invention containing Al more than 0 and less than 5% by mass has a tensile strength of 270 MPa or more and an elongation of 10% or more. The alloy material of the present invention containing 5% by mass to 12% by mass of Al has a tensile strength of 300 MPa or more and an elongation of 7% or more. In addition, the measurement of elongation shall be performed by GL (mark distance) = 25mm.

  Since the alloy material of the present invention has high strength and excellent corrosion resistance as described above, it is not only in a specific environment such as in an engine room, but also in a normal environment where it is exposed to the atmosphere, wind and rain, or in direct contact with the human body. Suitable for the structural material used. Specifically, it is used for casings and parts of portable electric devices such as mobile phones, casings and parts of home appliances such as personal computers, and exterior members such as frames in transportation and movement means such as bicycles and automobiles. be able to.

  Since the alloy material of the present invention adjusts the composition to enhance the corrosion resistance of the alloy itself, it can be used satisfactorily even in an environment where it is exposed to the atmosphere or wind and rain without performing surface treatment. Further, the alloy material of the present invention can suppress the progress of corrosion because the alloy itself is excellent in corrosion resistance even if the surface treatment layer is dropped or peeled off when the surface treatment is performed. In particular, the alloy material of the present invention has sufficient strength as a structural material by being subjected to plastic working, and can withstand long-term use. The alloy material of the present invention is lightweight because it does not contain a rare earth element, and can be used as a structural material in various fields where weight reduction is desired. Furthermore, since the rare earth element is not contained, the alloy material of the present invention can also reduce the manufacturing cost.

Embodiments of the present invention will be described below.
(Test Example 1)
A magnesium alloy having the composition shown in Table 1 (unit of content of additive element is mass%) was melted and cast to obtain a cylindrical cast material having a diameter of 30 mm. The obtained cast material was subjected to the following heat treatment and plastic working, and each of the obtained samples was subjected to a tensile test, a structure observation, and a corrosion resistance test.

  Samples A to E in Table 1 are samples mainly composed of an AZ91 equivalent alloy, samples F to J are samples mainly composed of an AZ61 equivalent alloy, and samples K to O are samples mainly composed of an AZ31 equivalent alloy. Sn is further added to Samples A to D, F to I, and K to N, and Sn is not added to Samples E, J, and O. Further, Si and Ca are further added to the samples D, I, and N. Sample P in Table 1 is a sample corresponding to pure magnesium, Sample Q is a sample of a binary alloy to which Sn is added, Sample R is a sample of a binary alloy to which Al is added, Samples S and T are Sn and It is a sample of a ternary alloy to which Al is added.

Samples C, H, and M are samples subjected to solution treatment at 400 ° C. × 10 hours after casting, and further subjected to heat treatment (temperature: 200 ° C., holding time: time shown in Table 1). That is, the sample is not subjected to plastic working.
Samples B, G, and L were subjected to a solution treatment at 400 ° C. for 10 hours after casting, and then subjected to surface grinding to form a cylindrical material having a diameter of 25 mm, and the cylindrical material was heated to 400 ° C. up to 20 mm. This sample was subjected to hot rolling (total cross-section reduction rate: 36%) and after heat rolling, heat treatment (temperature: 200 ° C., holding time: time shown in Table 1). The rolling process was performed at a cross-section reduction rate of about 10% / pass and a linear speed of 1 m / min. The rolling conditions are the same for the following samples.
Samples A, D to F, I to K, and N to T were subjected to solution treatment at 400 ° C. for 10 hours after casting, and then subjected to surface grinding to obtain a cylindrical material having a diameter of 25 mm. Hot rolled to φ20 mm in a state heated to ℃, and the obtained rolled material was drawn to φ15 mm in a state heated to 180 ° C. (total cross section reduction rate: 64%), and after drawing, heat treatment (temperature: 200 ° C., holding time: time shown in Table 1). Drawing was performed at a temperature increase rate to 180 ° C .: 20 ° C./sec, a processing degree: 10-15% / pass, and a linear speed: 1 m / min.
In addition to the above samples, samples A ′, F ′ and K ′ were prepared, which are not shown in Table 1. These samples A ′, F ′, and K ′ have the same composition as the samples A, F, and K, and the processes up to the drawing process are performed in the same manner as the samples A, F, and K. After the drawing process, heat treatment is performed. There is no sample.

The tensile test was performed at room temperature according to JIS Z 2241, and the tensile strength (TS), 0.2% proof stress (0.2% PS), and elongation (EL) were measured. The elongation was carried out with GL = 25 mm.
The corrosion resistance test was performed according to JIS Z 2371 (salt water spraying time: 1000 hours), and the amount of weight change (corrosion loss) before and after salt water spraying was measured.
In the tissue observation, the cross section of the sample was observed with an optical microscope (magnification: 400 times). The average crystal grain size of the alloy and the average diameter of the Sn-containing precipitates were determined by measuring the size of crystal grains and precipitates existing within a specific area (200 μm × 150 μm) in the same section according to the cutting method. The calculation was performed for three cross sections, and the average of the particle diameters of all the obtained crystal grains and the average of the size of all the precipitates were calculated.
Table 2 shows the results of the tensile test, the corrosion resistance test, and the structure observation.

  As shown in Table 2, it can be seen that the plastic working material to which a specific amount of Sn is added is excellent in strength and significantly improved in corrosion resistance. In this way, the corrosion resistance could be improved by adding a specific amount of Sn and applying plastic working to reduce the crystal grain size and the precipitate size containing Sn to reduce the structure. This is considered to be due to the fact that it could be uniformly dispersed therein. In particular, in addition to performing plastic working, the obtained magnesium alloy material is more excellent in corrosion resistance by appropriately combining heat treatment. Table 2 also shows that the corrosion resistance of the magnesium alloy material can be improved by adding a specific amount of Sn regardless of the Al content. Furthermore, it can be seen from Table 2 that when the Al content is high, the strength is excellent, and when the Al content is low, the toughness is excellent. In addition, it can be seen that the strength of the magnesium alloy material can be further improved by adding elements such as Al, Zn, and Mn.

(Test Example 2)
The cast material obtained by melting and casting the magnesium alloy having the composition shown in Table 3 (unit of content of additive element is mass%) was subjected to the following heat treatment and plastic working, and each of the obtained samples was subjected to Test Example 1 and Similarly, a tensile test, a structure observation, and a corrosion resistance test were performed.

Samples a to c in Table 3 are samples mainly composed of an AZ91 equivalent alloy, and Sn is further added.
For sample a, a plate-shaped cast material having a thickness of 10 mm was prepared, and this cast material was subjected to a solution treatment at 400 ° C. for 10 hours, and the obtained heat-treated material was heated to 200 to 400 ° C. to obtain a thickness of 2 This sample was subjected to heat treatment at 200 ° C. for 4 hours after hot rolling to 0.0 mm (total rolling reduction: 80%).
For sample b, a cylindrical cast material having a diameter of 30 mm was prepared, and the cast material was subjected to a solution treatment at 400 ° C. for 10 hours, and then subjected to surface grinding to obtain a cylindrical material having a diameter of 25 mm. It is a sample that was heated to 200 ° C., subjected to hot forging to φ10 mm (total cross section reduction rate: 84%), and then subjected to heat treatment at 200 ° C. for 4 hours.
For sample c, a cylindrical cast material having a diameter of 100 mm was prepared, and this cast material was subjected to a solution treatment at 400 ° C. for 10 hours. The obtained heat-treated material was heated to 400 ° C. and extruded, and a 5 mm thick plate was obtained. It is a sample obtained by subjecting this plate-like material to heat treatment at 200 ° C. for 4 hours.
Table 4 shows the results of the tensile test, the corrosion resistance test, and the structure observation.

  As shown in Table 4, it can be seen that an alloy material obtained by subjecting a cast material made of a magnesium alloy to which a specific amount of Sn is added to plastic processing such as forging and extrusion to high strength and excellent corrosion resistance. In addition, it can be seen from this test result that not only a linear material but also a magnesium alloy plate material having high strength and excellent corrosion resistance can be obtained.

  In the test examples described above, rolling, drawing, forging, and extrusion are performed as plastic processing, but press processing, bending, swaging, and the like can also be applied.

  The alloy material of the present invention can be suitably used as a structural material. Specifically, it is used for casings and parts of portable electric devices such as mobile phones, casings and parts of home appliances such as personal computers, and exterior members such as frames in transportation and movement means such as bicycles and automobiles. be able to.

Claims (7)

0.1 to 10.0% by mass of Sn, with the balance being Mg and inevitable impurities,
Magnesium alloy material characterized by being subjected to plastic working. 0.1 to 10.0% by mass of Sn, with the balance being Mg and inevitable impurities,
A magnesium alloy material having an average crystal grain size of 30 μm or less. 0.1 to 10.0% by mass of Sn, with the balance being Mg and inevitable impurities,
A magnesium alloy material characterized in that an average diameter of a compound containing Sn existing in an arbitrary cross section is 5.0 μm or less. In mass%, Al contains more than 0 and less than 5%, Sn contains 0.1 to 10.0%, and the balance consists of Mg and inevitable impurities,
A magnesium alloy material having a tensile strength of 270 MPa or more and an elongation of 10% or more.
However, the measurement of elongation shall be GL = 25 mm. It contains 5 to 12% Al and 0.1 to 10.0% Sn in mass%, and the balance consists of Mg and inevitable impurities,
A magnesium alloy material having a tensile strength of 300 MPa or more and an elongation of 7% or more.
However, the measurement of elongation shall be GL = 25 mm. Further, the magnesium alloy material is, in mass%, Al: 1 to 12%, Si: 0.1 to 2%, Ca: 0.01 to 3%, Zn: 0.1 to 2%, Mn: 0.1 to 0.1%. The magnesium alloy material according to claim 2 or 3 , comprising at least one element selected from the group consisting of 2%.   Further, the magnesium alloy material is in mass%, and Si: 0.1 to 2%, Ca: 0.01 to 3%, Zn: 0.1 to 2%, Mn: 0.1 to 2%. The magnesium alloy material according to claim 4 or 5, comprising at least one element selected.