JP2006088435A - Magnesium-based metal clad sheet - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a magnesium-based metal clad sheet excellent in press moldability and having corrosion resistance. <P>SOLUTION: The magnesium-based metal clad sheet is equipped with a magnesium-based metal layer 2 formed of a magnesium-based metal comprising pure Mg or a Mg-base alloy based on Mg and the corrosion-resistant metal layer 3 laminated on one side or both sides of the magnesium-based metal layer 2 and formed of a corrosion-resistant metal having corrosion resistance more excellent than that of the magnesium-based metal. The magnesium-based metal constituting the magnesium-based metal layer 2 is characterized in that the (0001) surface of the crystal structure thereof, that is, the base thereof has a crystal orientation inclined with respect to the surface of the magnesium type metal clad sheet. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to digital cameras, notebook computers, MD / CD / DVD recording / playback devices, video cameras, mobile phones, various electronic / electric equipment cases such as wristwatches, medical equipment such as wheelchairs, artificial bones, golf clubs, competitions, etc. The present invention relates to a lightweight clad material suitable as a material for sports equipment such as bicycles and automobile parts.

The casings of various electronic / electrical devices are formed of materials such as stainless steel, titanium, and aluminum alloys. Also, an aluminum metal clad material imparted with the lightness of an aluminum alloy and the characteristics of dissimilar metals not found in aluminum is proposed in Japanese Patent Application Laid-Open No. 2002-294376 (Patent Document 1).
On the other hand, in recent years, magnesium, which has the smallest specific gravity among practical metals, has been attracting attention as a material for a housing in order to reduce the weight of the housing, and some of them have begun to be used for manufacturing the housing as a cast product.
Magnesium alloys are used as materials for sports equipment such as golf clubs and competition bicycles because of their high specific strength and excellent vibration resistance.
JP 2002-294376 A

  Regardless of the casting of magnesium, there are the following problems in plastic deformation and forming into various forms. That is, Mg and an Mg-based alloy containing the same as a main component (hereinafter collectively referred to as “magnesium-based metal”) have a dense hexagonal crystal (hcp) crystal structure. The dominant slip system is the bottom slip. However, since the (0001) plane, that is, the bottom surface is entirely parallel to the plate surface, the bottom surface slip hardly occurs and the moldability is poor. For this reason, it is usually press-molded in a state heated to about 200 to 300 ° C. Moreover, since a magnesium-type metal is not good in corrosion resistance, there exists a problem that a use is limited.

  This invention is made | formed in view of this problem, and it aims at providing the magnesium type metal material which was excellent in press-formability and was equipped with corrosion resistance.

  The present inventor manufactured a clad plate in which a magnesium-based metal plate and a corrosion-resistant metal plate having different ductility were roll-welded, and examined the formability thereof. As a result, the formability was dramatically higher than that of a single plate of magnesium-based metal. Thus, the present inventors have found that molding can be performed at a lower temperature than in the past, and the present invention has been completed.

That is, the present invention provides a magnesium-based metal layer formed of magnesium-based metal made of pure Mg or an Mg-based alloy containing Mg as a main component, and is laminated on one or both surfaces of the magnesium-based metal layer. A magnesium-based metal clad plate provided with a corrosion-resistant metal layer formed of a corrosion-resistant metal having a corrosion resistance superior to that of a metal-based metal, wherein the magnesium-based metal forming the magnesium-based metal layer is a bottom surface of its crystal structure, that is, (0001 ) The surface is inclined with respect to the plate surface.
According to the clad plate of the present invention, the bottom surface is inclined with respect to the plate surface. Further, in the deep drawing process, the corrosion-resistant metal layer on the outer surface bears the maximum tensile stress, and the moldability is improved because the tensile stress load on the inner magnesium-based metal layer is reduced. For this reason, when shaping | molding using a clad board, the processing temperature of a magnesium-type metal can be lowered | hung and productivity can be improved. Moreover, the corrosion resistance of a magnesium-type metal layer can be improved by coat | covering a magnesium-type metal layer with a corrosion-resistant metal layer.

  The corrosion resistant metal is preferably pure Ti or a Ti alloy mainly composed of Ti. Ti or Ti alloy is excellent in weldability and corrosion resistance, and has high specific strength, and is therefore suitable for reducing the weight of the clad plate. Moreover, since the color developability after press molding is excellent, a color tone having a high commercial value can be imparted. Furthermore, since titanium and magnesium are harmless to the human body and are allergy free, clad plates using pure Ti or Ti alloys as corrosion-resistant metals are used for biomaterials such as artificial bones and medical device materials such as wheelchairs. Can also be used suitably.

  The magnesium-based metal forming the magnesium-based metal layer may have a θ of 1 ° to 45 °, where θ is the angle between the bottom surface of the crystal structure and the plate surface. As θ is increased to some extent, the formability is improved. However, in order to increase θ, it is necessary to apply a large shearing force to the magnesium-based metal layer. If θ is greater than 45 °, cracks may occur. Increases and decreases productivity. For this reason, θ is preferably 1 ° to 45 °. Further, the thickness of the magnesium-based metal layer is preferably 50% or more of the total thickness of the clad plate. Increasing the layer thickness ratio of the magnesium-based metal layer can contribute to weight reduction.

The magnesium-based metal clad plate manufacturing method of the present invention includes a magnesium-based metal plate formed of a magnesium-based metal made of pure Mg or an Mg-based alloy containing Mg as a main component, and more resistant to corrosion than the magnesium-based metal. A corrosion-resistant metal plate formed of an excellent corrosion-resistant metal is prepared and annealed, and then the one or both surfaces of the magnesium-based metal plate are overlaid with a corrosion-resistant metal plate and roll-welded in a temperature range of 200 to 400 ° C. To do.
By superposing the annealed magnesium-based metal plate and the corrosion-resistant metal plate and roll-welding this overlapping material at 200 to 400 ° C., due to the difference in ductility between the magnesium-based metal and the corrosion-resistant metal, With the shear stress acting, the magnesium-based metal layer and the corrosion-resistant metal layer can be easily formed while the c-axis of the magnesium-based metal crystal structure (hcp) is tilted and the bottom surface is tilted with respect to the rolling surface (plate surface). Can be joined.

  In the magnesium-based metal clad plate of the present invention, the bottom surface of the crystal structure of the magnesium-based metal forming the magnesium-based metal layer is inclined with respect to the plate surface, so that the bottom surface slip can be actively activated. For this reason, the processing temperature at the time of shaping | molding can be reduced combined with the high moldability of the corrosion-resistant metal layer of the outer surface which is excellent in press moldability and is rich in ductility. Moreover, since the corrosion-resistant metal layer is laminated on the magnesium-based metal layer, the corrosion resistance of the magnesium-based metal layer is improved. Furthermore, since the manufacturing method of the present invention allows a shear stress to act on the magnesium-based metal layer during roll pressure welding, the bottom surface of the magnesium-based metal crystal structure is easily tilted with respect to the rolling surface (plate surface). be able to.

Hereinafter, a magnesium-based metal clad plate according to an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 shows a clad plate 1 according to a first embodiment (two-layer structure), in which a corrosion-resistant metal layer 3 is roll-welded to one surface (one side) of a magnesium-based metal layer 2 and diffusion-bonded by heat treatment. is there. FIG. 2 shows a clad plate 1A according to the second embodiment (three-layer structure). Corrosion-resistant metal layers 3 and 3 are roll-welded to both surfaces (both sides) of the magnesium-based metal layer 2, and diffusion bonding is performed by heat treatment. It has been done.

  As the magnesium-based metal that forms the magnesium-based metal layer 2, pure Mg having a crystal structure of hcp, or an Mg-based alloy mainly composed of Mg can be used. Pure Mg is preferably composed of Mg content of 95 mass% or more and the balance of inevitable impurities. The Mg-based alloy is preferably a Mg alloy having a good ductility with an Mg content of preferably 85 mass% or more, more preferably 90 mass% or more, and Mg- (2 to 10 mass%) Al- (0.5 to 2 mass). %) Zn-based alloy and Mg- (0.5-4 mass%) Zn- (0.3-1.0 mass%) Zr-based alloy.

  As the corrosion-resistant metal that forms the corrosion-resistant metal layer 3, a ductile metal that is superior in corrosion resistance and rich in workability to magnesium-based metal can be used. When specific strength is large and a reduction in weight is particularly intended, pure Ti or a Ti-based alloy containing Ti as a main component is preferable. These titanium-based metals have excellent color developability after molding, are also harmless to the living body, and have the advantages of being allergy-free. The pure Ti is preferably one having a Ti amount of 99% or more, represented by JISH4600 1-4. As the Ti-based alloy, α-type alloys such as Ti-5Al-2.5Sn and Ti-8Al-1V-1Mo, Ti-6Al-4V, Ti-6Al-2Sn-4Zr-6Mo, and Ti-6Al- are preferable. Β-type alloys such as 6V-2Sn and the like, Ti-15V-3Cr-3Sn-3Al, Ti-15Mo-2.7Nb-3Al-0.2Si, and Ti-Nb-based alloys for biological use (the numerical unit is mass) %) Can be used.

  As the corrosion-resistant metal, in addition to the titanium-based metal, pure nickel as the nickel-based metal, nichrome or monel metal, cupro-nickel, brass (especially 7/3 brass, 65/35 brass), and western white as the copper-based metal. Stainless steel can be used as an iron-based metal. Compositionally, Ni- (10-45 mass%) Cr, Ni- (10-50 mass%) Cu, Cu- (10-50 mass%) Ni, Cu- (10-45 mass%) Zn, Cu- (5-35 mass) %) Ni- (15-35 mass%) Zn Ni-based, Cu-based alloys and Fe-based alloys such as SUS304 and SUS430. In addition, since Al and Al alloy are inferior in corrosion resistance, they are not used as corrosion resistant metals in the present invention.

  Further, by using a metal having higher strength than the magnesium-based metal as the corrosion-resistant metal, a higher-strength magnesium-based metal clad plate can be manufactured. From the viewpoint of lightness, it is preferable to use the pure Ti or Ti-based alloy as the corrosion-resistant metal. However, the more ductile metal is used as the corrosion-resistant metal, the more the corrosion-resistant metal layer is formed on the outer die side when the clad plate is deep-drawn, so that the generation of cracks at the die corner can be suppressed. There are advantages. For this reason, it is desirable to use a corrosion-resistant metal having appropriate strength and ductility depending on the molding mode of the clad plate.

  In the clad plate according to the first and second embodiments, as shown in FIG. 3, the magnesium-based metal forming the magnesium-based metal layer 2 is such that the c-axis of its crystal structure (hcp) is the plate surface (rolled surface). It is inclined with respect to the normal line, and its bottom surface, that is, the (0001) plane is inclined with respect to the plate surface. When the angle formed between the bottom surface and the plate surface is θ, θ is preferably 1 ° or more. As θ is increased to some extent, the bottom surface slip becomes more active during press forming, and the formability is improved. However, in order to tilt the bottom surface, it is necessary to apply a shear stress to the magnesium-based metal layer at the time of roll pressure welding. The larger the shear stress, the larger θ, but the possibility of cracking in the magnesium-based metal layer also increases, so θ is set to 45 ° or less. However, in order to incline θ greatly, the roll pressure contact condition becomes strict, so in consideration of this point, θ is preferably about 30 ° or less, more preferably 20 ° or less. As will be apparent from the examples described later, in the case of a magnesium-based metal plate, when θ = 0 °, the molding temperature was required to be 200 ° C. or more at the time of molding, but in the clad plate, by simply tilting θ, The molding temperature can be significantly reduced. Note that an angle between the (0001) plane which is the bottom surface of hcp and the rolling surface can be obtained by obtaining a pole figure by X-ray diffraction and examining the crystal orientation distribution of the magnesium-based metal layer.

  In the case of the two-layer clad plate 1, as the ratio of the thickness of the magnesium-based metal layer 2 to the entire thickness increases, the ratio of the magnesium-based metal layer increases, and the weight reduction can be promoted. On the other hand, if the thickness ratio exceeds 95% and is not excessively severe, the action of shear stress is difficult to reach the entire magnesium-based metal layer 2 at the time of roll pressure welding, and the magnesium-based metal. The c-axis of the crystal structure hcp of the layer, in other words, the inclination of the bottom surface = (0001) plane is less likely to occur, and the risk of damage to the magnesium-based metal layer increases. Therefore, the lower limit of the magnesium-based metal layer thickness / cladding plate thickness is 50%, more preferably 60%, and the upper limit is preferably 95%, more preferably 90%, and even more preferably 85%. Is desirable. On the other hand, in the case of the clad plate 1A having a three-layer structure, even if the thickness ratio of the magnesium-based metal layer is the same as that of the two-layer structure, the shear stress tends to be slightly less likely to act on the magnesium metal layer 2, so It is desirable to keep it at 90% or less, more preferably 85%. Further, the deep drawability of the clad plate is influenced not only by the inclination of the bottom surface of the magnesium-based metal layer 2 but also by the ductility and thickness of the corrosion-resistant metal layer 3 disposed on the die side. In general, the deep drawability of the corrosion-resistant metal increases as the ductility of the corrosion-resistant metal increases. For this reason, when emphasizing deep drawability, it is desirable to secure a thickness ratio of the corrosion-resistant metal layer 3 provided on one side of the magnesium-based metal layer 2 to the cladding plate of 5% or more, preferably 10% or more.

Next, the manufacturing method of the clad plate of this invention is demonstrated.
A magnesium-based metal plate formed of the magnesium-based metal and a corrosion-resistant metal plate formed of the corrosion-resistant metal are prepared. First, these metal plates are annealed to remove work strain and soften. The magnesium-based metal plate may be heated at a temperature of about 250 to 400 ° C., and when titanium is used as the corrosion resistant metal, it may be heated at a temperature of about 600 to 800 ° C. Although the heating time depends on the plate thickness, when the plate thickness is about 600 μm, the magnesium metal plate may be about 5 to 10 minutes and the titanium plate may be about 5 to 10 minutes. The annealing is preferably performed in a non-oxidizing atmosphere such as a hydrogen gas atmosphere, a nitrogen gas atmosphere, and an argon gas atmosphere or in a vacuum for the magnesium-based metal plate. Moreover, when using a titanium-type metal plate as a corrosion-resistant metal plate, it is preferable to carry out in an argon gas atmosphere or in a vacuum.

  Next, these metal plates are superposed, and the superposed material is roll-welded at a temperature of about 200 to 400 ° C. Usually, it can roll at the said temperature by heating the said laminated material a little higher than the said temperature, and letting it pass to a rolling roll rapidly. Of course, the roll may be preheated to the same temperature as the laminated material. Heating is preferably performed in an inert atmosphere such as an argon gas atmosphere or in a vacuum. A clad plate in which the magnesium-based metal layer and the corrosion-resistant metal layer are joined is obtained by roll pressure welding. A shear stress acts on the magnesium-based metal layer at the time of the roll pressure contact, whereby the bottom surface of the crystal structure of the magnesium-based metal forming the magnesium-based metal layer is inclined with respect to the rolling surface.

  As described above, the temperature range during the roll pressure contact is 200 to 400 ° C., preferably about 250 to 380 ° C. When it exceeds 400 ° C., the magnesium-based metal is greatly softened, the elongation is increased, and the bonding state is deteriorated. On the other hand, when the temperature is lower than 200 ° C., the bondability between the magnesium-based metal layer and the corrosion-resistant metal layer is deteriorated, and cracks may occur in the magnesium-based metal layer under roll pressure.

Moreover, the rolling reduction at the time of roll pressing is about 20 to 40%, preferably about 25 to 35% when rolling in the temperature range. If it is less than 20%, poor bonding is likely to occur, the shear stress acting on the magnesium-based metal layer is insufficient, and the inclination of the bottom surface of the crystal structure is reduced. On the other hand, if it exceeds 40%, cracks are likely to occur in the magnesium-based metal layer.
By finally heat-treating the clad plate subjected to roll pressure welding at 250 to 400 ° C., diffusion of the magnesium-based metal and the corrosion-resistant metal can be promoted, and the bonding between them can be ensured. The heat treatment is preferably performed in an inert atmosphere such as an argon gas atmosphere or in a vacuum.

  EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated more concretely, this invention is not limitedly interpreted by this Example.

  Magnesium-based metal plates (“Mg”) of various thicknesses made of industrial pure Mg (JIS type 1) or Mg-based alloy (JIS H4201 MP1 equivalent material AZ31: Mg-2.7 mass% Al-1.1 mass% Zn) And titanium plates of various thicknesses (abbreviated as “Ti plate”) made of industrial pure Ti, and the Mg plate in an argon gas atmosphere at 300 ° C. for 10 minutes. The Ti plate was annealed by heating at 750 ° C. for 10 minutes in an argon gas atmosphere.

  Next, after cleaning the surfaces of the Mg plate and the Ti plate with acetone, the surfaces of the joints are rubbed with a metal brush to activate the surfaces, and the activated surfaces are overlapped to form a laminated material. The laminated material (total thickness: 1.3 mm) was heated at 300 ° C. for 10 minutes in an argon gas atmosphere, and was reduced at a reduction rate of 30% using a rolling roll. A two-layer clad plate or a three-layer clad plate of Ti layer-Mg layer-Ti layer was obtained. In the case of a three-layer clad plate, the two Ti layers have the same thickness. Finally, the clad plate was heat-treated at 300 ° C. for 10 minutes in an argon gas atmosphere. Table 1 shows the thickness ratio of the Mg plate and the Ti plate on one side with respect to the total thickness of the superposed material. The ratio with respect to the total thickness of the Mg layer in the clad plate was about 3 to 5% lower than the ratio of the Mg plate in the laminated material. As a comparative example, using the annealed Mg plate, 0.9 mm thick single layer plate samples (Nos. 1 and 2 in Table 1) were manufactured under the same conditions as the clad plate. In addition, the annealed Mg plate was rolled at a different peripheral speed and subjected to the same heat treatment as described above to produce a single-layer sample (No. 3 in Table 1) having a thickness of 0.9 mm.

  A 30 mm square sample was collected from the clad plate and single layer plate produced as described above, and the inclination of the bottom surface of the magnesium-based metal forming the Mg layer was examined as follows. Polishing the sample from the surface to expose an observation surface passing through the central portion in the thickness direction of the Mg layer, and (0001) pole figure of a magnesium-based metal forming an Mg layer by X-ray diffraction on the observation surface And the deviation angle (tilt angle of the bottom surface) from the center of the peak position was measured. The results are also shown in Table 1.

  Next, a disc-shaped blank (molding test piece) having a diameter of 25 mm was collected from each sample, and a deep drawing molding test was performed using the blank as described below. As shown in FIG. 4, the blank B is placed on a die 21 having a shoulder radius of 4.0 mm so that the Ti layer is on the lower side (die side), and the outer periphery of the blank B is pressed with a blank holder 23. A punch 22 having a diameter of 15 mm (drawing ratio: 1.67) and a shoulder radius of 2 mm was moved to the die 21 side, and the blank B was pushed into the forming hole of the die 21 to form a cup. During molding, the molding temperature was controlled to 75 to 250 ° C. by the heater 24 attached to the outer periphery of the die 21. The descending speed (crosshead speed) of the punch 22 was 0.17 mm / s, and molybdenum disulfide paste was used as the lubricant. The test results are also shown in Table 1. In the table, “◯” indicates that no crack occurred, and “×” indicates that a crack occurred in the die corner of the cup.

  From Table 1, a pure Mg or AZ31 single-layer plate having a bottom inclination of 0 ° requires heating at least 200 ° C. to perform deep drawing, but the invention is clad with pure Mg or AZ31 and Ti. In the example, in the case of the two-layer clad plate, it can be seen that the molding temperature is lowered by 100 ° C. or more even when the inclination of the bottom surface of the Mg layer is about 2 °, and the moldability is dramatically improved.

It is a cross-sectional schematic diagram of the clad board concerning 1st Embodiment. It is a cross-sectional schematic diagram of the clad board concerning 2nd Embodiment. It is a crystal orientation schematic diagram of magnesium after roll pressure welding. It is a deep drawing forming test point explanatory drawing in an example.

Explanation of symbols

1,1A Clad plate 2 Magnesium metal layer 3 Corrosion resistant metal layer

Claims (6)

  It is laminated on the surface of one or both of a magnesium-based metal layer made of pure Mg or a magnesium-based metal composed of Mg-based alloy containing Mg as a main component and the magnesium-based metal layer, and is more resistant to corrosion than the magnesium-based metal. A magnesium-based metal clad plate provided with a corrosion-resistant metal layer formed of an excellent corrosion-resistant metal, wherein the magnesium-based metal forming the magnesium-based metal layer has a bottom surface of the crystal structure inclined with respect to the plate surface. Magnesium metal clad plate.   The clad plate according to claim 1, wherein the corrosion-resistant metal is formed of pure Ti or a Ti alloy containing Ti as a main component.   3. The clad plate according to claim 1, wherein the magnesium-based metal forming the magnesium-based metal layer has a θ of 1 ° to 45 °, where θ is an angle between the bottom surface of the crystal structure and the plate surface.   The clad plate according to any one of claims 1 to 3, wherein the magnesium-based metal layer has a thickness of 50% or more of a total thickness of the clad plate.   A magnesium-based metal plate formed of pure Mg or a magnesium-based metal composed of Mg-based alloy containing Mg as a main component, and a corrosion-resistant metal plate formed of a corrosion-resistant metal superior in corrosion resistance to the magnesium-based metal are prepared. A method for producing a magnesium-based metal clad plate, comprising: annealing and then superimposing a corrosion-resistant metal plate on one or both surfaces of the magnesium-based metal plate and roll-welding at a temperature of 200 to 400 ° C. The manufacturing method according to claim 5, wherein the rolling reduction during roll pressing is 20 to 40%.

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