JP6408824B2 - Metal clad welding material and method for producing metal clad welding material - Google Patents

Description

  The present invention relates to a metal clad weld material obtained by welding metal clad materials and a method for producing the same, and more particularly to a weld material obtained by welding clad materials obtained by clad metals having a large melting point difference and a method for producing the same.

A clad material in which two different kinds of metals (pure metal or alloy) are clad is known. As an example of a clad material, Patent Document 1 discloses a clad material of a magnesium alloy and another metal such as titanium or a titanium alloy. In the case of clad material of magnesium alloy and titanium alloy (or pure titanium), it is lightweight by taking advantage of the characteristics of titanium with excellent corrosion resistance and high specific strength and the characteristics of magnesium alloy that is lightweight and relatively high in strength. And it has the advantage that high corrosion resistance and high strength can be realized.
Thus, the clad material clad with two types of metals can take advantage of the advantages of the respective metals and obtain characteristics that cannot be obtained with a shape material made of one type of metal.

JP 2010-155357 A

However, some cladding materials are difficult to weld. For example, if the clad material of the above magnesium alloy and titanium is to be welded using a conventional welding method, if the titanium having a high melting point is heated until it is melted, the magnesium alloy having a low melting point is similarly heated. , It evaporates beyond the boiling point, making it impossible to obtain a welding material. When the melting points of two kinds of clad metals such as magnesium alloy and titanium alloy are greatly different from, for example, 800 ° C. or more, the metal having the higher melting point is heated by the conventional welding method. When it was melted in this manner, the metal having a low melting point was heated in the same manner, causing an overheating phenomenon such as evaporation or outflow, and welding could not be performed.
For this reason, it becomes difficult to process the clad material into a desired shape such as a pipe shape, a plate material having a larger surface area, and a rectangular tube shape, and there is a problem in that the use of the clad material is limited.

  Accordingly, an object of the present invention is to provide a welding material obtained by welding a clad material clad with two kinds of metals having melting points greatly different from 800 ° C. or higher, and to provide a method for manufacturing the welding material.

  One aspect of the present invention is: 1) a first metal layer made of a first metal, and a second metal having a melting point higher than that of the first metal by 800 ° C. or higher and a thermal conductivity of 1/3 or less. A step of disposing two opposite ends of the clad material clad with the second metal layer, and 2) a part of the surface of the second metal layer while cooling the surface of the first metal layer The first metal layer at the two end portions is irradiated with a laser to melt a part of the second metal layer at at least one of the two end portions and transfer heat from the second metal. A step of melting a part of at least one of 3), and 3) solidifying the molten first metal and the molten second metal to form a solidified portion that connects the unmelted portions of the two ends. A process for producing a clad welding material.

  According to another aspect of the present invention, there is provided a first metal layer made of the first metal, a second metal having a melting point higher than that of the first metal by 800 ° C. or higher and a thermal conductivity of one third or less. A clad portion clad with a second metal layer made of a metal, and a welded portion connecting between the two clad portions and having a solidified structure, wherein the solidified portion is a portion of each of the two clad portions. A first solidified portion connecting the first metal layers and made of the first metal; and a second solidified portion connecting the second metal layers of each of the two cladding portions and made of the second metal. And the length of the surface of the said 1st solidification part is longer than the length of the surface of the said 2nd solidification part in the direction which connects the said 2 clad part, It is a clad welding material characterized by the above-mentioned.

  According to the present invention, it is possible to provide a clad weld material obtained by welding clad materials clad with two kinds of metals having melting points greatly different from 800 ° C. or higher. Also, it is possible to provide a method for manufacturing such a welding material.

FIG. 1 is a schematic perspective view illustrating a method for manufacturing a clad welding material according to one embodiment of the present invention. FIG. 2 is a schematic cross-sectional view showing a cross section of the clad welding material 100 according to one embodiment of the present invention. FIG. 3 shows the surface observation result of the sample of Example 9 as an example of the surface observation result. FIG. 3A shows the surface observation result of the second metal layer, and FIG. 3B shows the surface observation result of the first metal layer. FIG. 4 is a plan view showing the shape of the tensile test piece used. FIG. 5 shows a cross-sectional photograph of a typical weld. 5 (a) shows a cross section of the sample of Example 4, FIG. 5 (b) shows a cross section of the sample of Example 5, FIG. 5 (c) shows a cross section of the sample of Example 9, and FIG. Shows the cross section of the sample of Example 10, and FIG. 5E shows the cross section of the sample of Example 12.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. However, it should be noted that the embodiments described below are intended to embody the technical idea of the present invention and are not intended to limit the technical scope of the present invention. The configuration described in one embodiment is applicable to other embodiments unless otherwise specified. In the following description, terms indicating a specific direction or position (for example, “up”, “down”, “right”, “left” and other terms including these terms) are used as necessary. The use of the terminology is intended to facilitate understanding of the invention with reference to the drawings, and the technical scope of the present invention is not limited by the meaning of these terms.

  As a result of intensive studies by the inventors of the present application, even if the clad material clad with two kinds of metals, that is, a first metal and a second metal whose melting point is 800 ° C. or higher than the first metal, the second metal In the case where the thermal conductivity of the first metal is as small as one-third or less of the thermal conductivity of the first metal, a method for welding the ends of the clad material has been found.

In the clad welding material manufacturing method (welding method) according to the present invention, the ends of the clad material clad with the first metal layer made of the first metal and the second metal layer made of the second metal are opposed to each other. Then, welding is performed by irradiating the surface of the second metal layer with a laser while cooling the surface of the first metal layer. The second metal layer is melted by the energy of the laser beam. The first metal layer having a low melting point is melted by heat transfer from the second metal layer heated and heated by the laser beam.
At this time, the first metal layer has a thermal conductivity that is at least three times larger than that of the second metal layer and its surface is cooled, so that the first metal layer conducts in the second metal layer relatively slowly. The heat that reaches the interface between the first metal layer and the second metal layer is transferred to the first metal layer, and a substantial part of the heat is conducted through the interior at a high speed, and reaches the cooling surface to reach the outside of the first metal layer. Is transmitted to.
For this reason, the temperature increase rate of the first metal layer is considerably slower than that of the second metal layer, and the first metal layer can be prevented from falling into an overheated state even though the melting point difference is 800 ° C. or more.
As a result, both the first metal layer and the second metal layer can be melted in an appropriate state. Thereafter, the solidified portion (welded portion) can be formed by cooling and solidifying the molten first metal and second metal.
Below, the detail of the manufacturing method of the clad welding material which concerns on this invention of this application is demonstrated.

1. Clad Welding Material Manufacturing Method FIG. 1 is a schematic perspective view illustrating a cladding welding material manufacturing method according to an embodiment of the present invention.
(1) Cladding material Two cladding materials 3 (in FIG. 1, one is shown as the cladding material 3A and the other is shown as the cladding material 3B) are prepared. In the clad material 3 (3A, 3B), a first metal layer 1 made of a first metal and a second metal layer 2 made of a second metal are clad (bonded).
The melting point of the second metal is 800 ° C. or higher, preferably 900 ° C. or higher, than the melting point of the first metal. That is, the first metal and the second metal are a combination of metals that have been difficult to weld between clad materials by conventional welding methods.

The thermal conductivity of the second metal is 1/3 or less of the thermal conductivity of the first metal. As described above, since the first metal has a considerably higher thermal conductivity than the second metal, the two cladding materials can be welded together by using the manufacturing method according to the present invention. In addition, although heat conductivity changes with temperature, heat conductivity here means the heat conductivity in room temperature.
As long as such a condition is satisfied, the first metal and the second metal may be any metal.
Examples of the first metal include magnesium (pure magnesium), magnesium alloy, aluminum (pure aluminum), and aluminum alloy. Examples of preferred magnesium alloys include AZ alloys including AZ61 alloy, and the composition ranges corresponding to such AZ alloys include Al: 1.4 to 10.0 mass%, Zn: 0.2 to 1.4 mass%. , Balance: Mg and other elements up to 4.0% by mass in total (one example of other elements is unavoidable impurities, another example is 0.2 to 1.0% by mass of Mn and And / or 0.025 to 2.5 mass% of Ca and inevitable impurities).
Examples of the second metal include titanium (pure titanium), titanium alloy, iron, and iron alloy (a concept including steel (including stainless steel)).

It is preferable that no intermetallic compound is formed between the main component of the first metal and the main component of the second metal. This is because, when a large amount of intermetallic compound is formed during solidification, the obtained welded portion may not have sufficient ductility.
Here, the “principal component” means an element that occupies the largest ratio by mass ratio, and in one preferred embodiment, means an element that is contained by 50% or more by mass ratio.

Further, in the process in which both the first metal and the second metal are melted and solidified, the main component of the first metal and the main component of the second metal are not mixed (not alloyed) 2. A phase separation state is preferred. The first metal (at least the main component of the first metal) and the second metal (at least the main component of the second metal) are phase-separated to correspond to the first metal layer in the obtained welded portion. This is because the first solidified portion made of the first metal and the second solidified portion made of the second metal corresponding to the second metal layer can be obtained. Details will be described later.
Such a combination of the first metal and the second metal that does not form an intermetallic compound between the main components and / or causes phase separation between the main components is, for example, the first metal Referring to the binary phase diagram of the main component of the metal and the main component of the second metal, respectively, confirm whether to form an intermetallic compound and / or whether the solid solubility limit of each element is sufficiently small Can be predicted.

  As a preferred combination of the first metal and the second metal, an intermetallic compound is not formed between the main components of each other, and phase separation occurs between the main components of the first metal, which is magnesium or a magnesium alloy. And a combination of a second metal that is one selected from titanium, a titanium alloy, iron, and an iron alloy. Here, the iron alloy is a concept including steel, and the steel is a concept including stainless steel. Further, when “alloy” is added after the name of a metal element such as “magnesium alloy”, it means an alloy containing the metal element as a main component. That is, “magnesium alloy” means an alloy containing magnesium as a main component.

Among these, for example, as shown in Patent Document 1, a clad material 3 in which the first metal is magnesium or a magnesium alloy and the second metal is titanium or a titanium alloy is preferable. Titanium and titanium alloy have the advantage that they have excellent corrosion resistance and high specific strength, and the clad material 3 combined with magnesium or a magnesium alloy having light weight and relatively high strength is more reliable and excellent. This is because corrosion resistance, high strength and light weight can be achieved. Further, when the first metal is magnesium or a magnesium alloy and the second metal is titanium or a titanium alloy, the thermal conductivity of the second metal is more reliably 3 of the thermal conductivity of the first metal. It has the advantage of being less than a fraction.
However, titanium has a high melting point of 1668 ° C. On the other hand, magnesium has a melting point as low as 650 ° C. and a boiling point of 1090 ° C., which is 500 ° C. lower than the melting point of titanium. For this reason, in the conventional welding method, when titanium or a titanium alloy is melted, most of the magnesium or the magnesium alloy is vaporized and welding cannot be performed.

  The first metal layer 1 and the second metal layer 2 of the clad material 3 preferably have a processed structure or a heat-treated structure obtained by heat-treating the processed structure. This is because preferable characteristics such as strength and ductility can be obtained. Examples of the processed structure include a rolled structure (hot or warm rolled structure, or cold rolled structure) and a drawn structure. Examples of the heat-treated structure obtained by heat-treating the processed structure include a recovered structure, a recrystallized structure, and a precipitated structure.

  The clad material 3 may be produced by any method including rolling (for example, the method described in Patent Document 1), drawing, explosion bonding, and diffusion bonding.

  Moreover, in embodiment shown in FIG. 1, although the clad material 3 (3A, 3B) has a plate-shaped shape with uniform thickness, it is not limited to this. The first metal layer 1 has an exposed surface (surface other than the joint with the second metal layer 2) for cooling during welding, and the exposed surface (first metal) on which the second metal layer 2 can be irradiated with a laser. It may have any shape as long as it has a surface other than the joint with the layer 1. Examples of such a shape include a plate having a uniform thickness, a tapered plate having a variable thickness, a cylinder, and a rectangular tube (a hollow shape having a polygonal cross section).

The thickness of the clad material 3 (the length in the z direction in FIG. 1) may be any thickness, but is preferably 0.1 mm or more and 10 mm or less, more preferably 0.2 mm or more and 5 mm or less. It is because a welding material can be obtained more reliably.
The ratio of the thickness of the first metal layer 1 and the second metal layer 2 in the clad material 3 may be an arbitrary ratio, but preferably when the thickness of the first metal layer 1 is 1, The thickness of the second metal layer 2 is 0.1 to 10.0, and more preferably the thickness of the second metal layer 2 is 0.2 to 5.0.
When the first metal is magnesium or a magnesium alloy and the second metal is one selected from titanium, a titanium alloy, iron, and an iron alloy, the clad material 3 makes the characteristics of lightweight magnesium more effective. In order to obtain it, it is preferable that the first metal layer 1 is thicker than the second metal layer 2.

  When the characteristics of the clad material 3 are anisotropic, for example, when the characteristics are different in a direction perpendicular to the direction parallel to the processing direction (rolling direction, drawing direction, etc.), the clad material 3A and the clad material 3B are arranged. The processing direction may be appropriately adjusted with respect to the direction (x direction in FIG. 1), for example, to be vertical or parallel. Further, when the clad material 3 is a rolled clad material, a long clad welded material can be obtained by making the direction in which the clad material 3A and the clad material 3B are arranged perpendicular to the rolling direction.

(2) Welding Conditions / Clad Material Arrangement As shown in FIG. 1, the end portion (particularly the end face) of the clad material 3A and the end part (particularly the end face) of the clad material 3B are placed opposite to each other. The clad material 3A and the clad material 3B may be arranged so as to perform so-called butt welding.
In this specification, the “end portion of the clad material” includes an end surface portion of the clad material and its vicinity, and includes a portion that is melted by laser welding, which will be described in detail later, and a portion that is not melted (unmelted portion). . For example, the region is within 5 mm from the end face of the clad material.
In order to ensure the strength (tensile strength) of the obtained welding material, it is preferable to arrange the clad material 3A and the clad material 3B so that the first metal layers 1 and the second metal layers 2 are in contact with each other. .
For this reason, for example, after obtaining flat end faces (preferably end faces perpendicular to the main surface) of the clad materials 3A and 3B using a method such as cutting of a rotating grindstone (micro cut), wire electric discharge machining, and laser cut, the clad material The end surfaces of 3A and the clad material 3B may be brought into contact with each other so that the first metal layers 1 and the second metal layers 2 of the clad material 3A and the clad material 3B are in contact with each other.

  However, the arrangement of the clad material 3A and the clad material 3B is not limited to this. Depending on the use of the clad welding material to be obtained, the clad welding material may be spaced apart so as to generate a gap of, for example, 1 mm or less between the clad material 3A and the clad material 3B. Further, only one of the first metal layers 1 and the second metal layers 2 of the clad material 3A and the clad material 3B may be brought into contact with each other.

In the embodiment shown in FIG. 1, the clad material 3A and the clad material 3B have the same shape, but the present invention is not limited to this. As described above, the clad material 3A and the clad material 3B may have different shapes as long as the end portions of the clad material 3A and the clad material 3B can be arranged to face each other.
In the embodiment shown in FIG. 1, the clad material 3A and the clad material 3B are separate and distinct clad materials. However, it is not limited to this. For example, the clad material 3A and the clad material 3B are formed of different portions of different clad materials (different clad materials) as in the case of forming a pipe by bending one plate-like clad material and welding the end faces to face each other. Part).

-Cooling of 1st metal layer The surface of the 1st metal layer 1 is cooled in the case of the laser welding which mentions details later. Cooling is a known option such as air cooling (for example, air flowing by a blower is brought into contact with the first metal layer 1), cooling by bringing a liquid such as water into contact (water cooling or the like), and contacting a radiator. The method may be used.
In the embodiment shown in FIG. 1, the radiator 14 is brought into contact with the cooling. The radiator 14 may be a metal plate, for example, and may be provided with fins. When a metal plate is used as the radiator 14, it is preferable to use a metal whose thermal conductivity is higher than that of the first metal as the metal constituting the metal plate. This is because the first metal layer 1 can be cooled more effectively. Examples of such metals include copper, copper alloys, aluminum, aluminum alloys, silver, and silver alloys.

  Moreover, the heat radiator 14 is preferably cooled by a liquid such as water or water containing a predetermined component such as a rust inhibitor (for example, water cooling). For example, the radiator 14 may be cooled by flowing such a liquid through a pipe provided inside the radiator 14, and the surface of the radiator 14 (for example, the surface not in contact with the first metal layer 1). The heat radiating body 14 may be cooled by contacting the liquid.

  The surface to be cooled is an exposed surface other than the joint surface between the first metal layer 1 and the second metal layer 2. A preferable surface is a surface opposite to the bonding surface between the first metal layer 1 and the second metal layer 2 as shown in FIG. This is because a portion of the first metal layer 1 located immediately below the second metal layer 2 heated by the laser beam can be efficiently cooled.

Laser welding The laser beam 12 emitted from the laser device 10 is exposed to the surface of the second metal layer 2 (the surface different from the bonding surface with the first metal layer 1 and exposed, in the embodiment of FIG. Is irradiated to a part (a part of the end of the clad material 3A and / or the clad material 3B).
And a welding part can be formed in the whole width direction (y direction of FIG. 1) of the clad material 3 by scanning the laser apparatus 10 in the direction of arrow A (direction parallel to y direction) of FIG. .

The laser device 10 used may be any type of laser device including a semiconductor laser, a fiber laser, a YAG laser, and a carbon dioxide laser.
The output of the laser device 10 may be an arbitrary output. For example, a preferable range is 200 W to 1 kW, and a more preferable range is 325 W to 600 W.
A preferable spot size (spot diameter) d1 of the laser beam 12 is 0.5 to 3.0 mm, and a more preferable spot size (spot diameter) d1 is 1.0 to 2.0 mm. However, the present invention is not limited to this, and the spot size (spot diameter) d1 may be appropriately selected according to other conditions.

In order to obtain a homogeneous welded portion (solidified portion), the laser beam 12 is applied to a part of both ends of the clad materials 3A and 3B (that is, the spot diameter d1 to which the laser beam is applied). It is preferable that the ends of the clad material 3A and the clad material 3B are in the region.
However, the present invention is not limited to this, and the laser beam 12 may be irradiated only on a part of one end of either the clad material 3A or the clad material 3B depending on the use of the obtained clad weld material. It is preferable (for example, only one end of either the clad material 3A or the clad material 3B is in the region of the spot diameter d1 irradiated with the laser beam). In this case, of the ends of the clad material 3A and the clad material 3B, a part of the end irradiated with the laser beam 12 is melted first, and then the laser is obtained by the heat obtained from the melted second metal. A part of the end portion that is not irradiated with the light beam 12 may be melted.

You may select the scanning speed of the laser apparatus 10 suitably. A preferable scanning speed is 2 mm / second to 30 mm / second, and a more preferable scanning speed is 4 mm / second to 12 mm / second. In the present specification, the “scanning speed of the laser device” means a relative speed between the laser device and the material to be welded (that is, the cladding materials 3A and 3B). Accordingly, the material to be welded may be moved instead of or in addition to moving the laser device.
In the embodiment shown in FIG. 1, the laser beam 12 is irradiated over the entire width direction of the cladding materials 3A and 3B, but the laser beam 12 is irradiated only to a part of the cladding materials 3A and 3B in the width direction. Alternatively, only a part of the clad materials 3A and 3B in the width direction may be welded. For example, a clad welding material formed by such spot welding can be used depending on the application, such as when strength is not so high.

  In order to prevent the molten first metal and / or second metal from coming into contact with the atmosphere, an inert gas such as argon or neon (in some cases, nitrogen gas may be used as a shielding gas for the welded portion. ) Is preferably supplied.

At least one (preferably both) of the end of the clad material 3A and the end of the clad material 3B is irradiated with the laser beam 12, and the end of at least one (preferably both) of the clad material 3A and the clad material 3B is irradiated. A part of the second metal layer 2 is melted (that is, a melted second metal appears). Further, due to heat transfer from the second metal heated by the laser irradiation, a part of the first metal layer 1 at the end of at least one (preferably both) of the clad material 3A and the clad material 3B is melted (that is, both). The first molten metal appears). Since the first metal has a high thermal conductivity and the surface of the first metal layer 1 is cooled, the first metal layer 1 melts in a state where overheating is suppressed.
As the laser device 10 moves away, the melted first and second metals decrease in heat input, and the temperature decreases and solidifies to form a weld.

  One of the advantages of the clad welding material manufacturing method (welding method) according to the present invention is that it is not necessary to supply a filler material and a flux using a welding rod or a welding wire. However, this does not mean that the filler material and the flux should not be used, and the filler material and / or the flux may be used as necessary.

2. Next, the clad welding material obtained by the above-described method for producing a clad welding material will be described.
FIG. 2 is a schematic cross-sectional view showing a cross section of the clad welding material 100 according to one embodiment of the present invention. Since the details of the form of the welded material vary depending on the welding conditions, the clad welded material 100 shown in FIG. 2 has one of the forms of the clad welded material obtained by the method for producing a clad welded material according to the present invention. It should be noted that this is an example.

  Of the end portion of the clad material 3A, the portion that was not melted (hereinafter referred to as “clad portion of the clad material 3A”) and the portion of the end portion of the clad material 3B that was not melted (hereinafter referred to as “the clad portion of the clad material 3B”). ”), A welded portion 23 is formed. The welded portion 23 has a solidified structure, and connects the clad portion of the clad material 3A and the clad portion of the clad material 3B.

  As described above, when the first metal and the second metal are selected so that an intermetallic compound is not formed between the main component of the first metal and the main component of the second metal, the solidified portion 23 is The intermetallic compound that causes embrittlement is substantially not contained, or even very little.

Further, in the process of solidifying the first metal and the second metal as described above, the main component of the first metal and the main component of the second metal are not mixed (not alloyed) 2. By selecting the first metal and the second metal so as to be in the phase separation state, as shown in FIG. 2, the solidified part 23 including the first solidified part 21 and the second solidified part 22 can be formed. it can.
The first solidified portion 21 connects the first metal layer 1 of the cladding material 3A and the first metal layer 1 of the cladding material 3B. Similarly, the second solidified portion 22 connects the second metal layer 2 of the clad material 3A and the second metal layer 2 of the clad material 3B.

Moreover, the 1st solidification part 21 consists of a 1st metal, and the 2nd solidification part 22 consists of a 2nd metal.
In the welding process, the components of the first metal layer 1 and the second metal layer 2 that have been heated to a high temperature and melted can be vaporized, and the first metal layer 1 and the second metal that have been melted can be vaporized. It is known to those skilled in the art that the composition of the welded part often does not become the same as the composition of the non-welded part (the part that is not melted during welding) because some of the components of the layer 2 may be mixed. It is common sense.
Therefore, “the first solidified portion 21 is made of the first metal” requires that the composition of the first solidified portion 21 is exactly the same as the composition of the first metal layer 1 of the cladding materials 3A and 3B. It means that at least the main components (elements) of each other are the same. Similarly, “the second solidified portion 22 is made of the second metal” requires that the composition of the second solidified portion 22 is exactly the same as the composition of the second metal layer 2 of the cladding materials 3A and 3B. It means that at least the main components (elements) of each other are the same.

As can be seen from the above, in the embodiment shown in FIG. 2, the solidified portion 23 includes the first solidified portion 21 and the second solidified portion corresponding to the first metal layer 1 and the second metal layer 2 of the cladding materials 3A and 3B, respectively. 22. For this reason, the solidified part (welded part) 23 can also obtain characteristics close to those of the clad material 3.
Such characteristics can include joint efficiency. The joint efficiency is a ratio of the strength of the clad welding material 100 to the strength of the clad material 3 before welding (corresponding to the strength of the welded portion because the welded portion is weakest).
When welding is performed under the above-described preferable welding conditions and the first solidified portion 21 and the second solidified portion 22 are formed in the solidified portion 23, a joint efficiency of 70% or more is obtained for 0.2% proof stress. As for tensile strength, a joint efficiency of 60% or more can be obtained.
In addition, there is a possibility that the properties unique to the clad material 3 utilizing the characteristics of the second metal layer (titanium, titanium alloy, stainless steel, etc.) having good corrosion resistance can be substantially achieved in the solidified portion 23 of the clad weld material 100. high.

In the embodiment shown in FIG. 1, the length L1 of the surface of the first solidified part 21 in the direction connecting the clad part of the clad material 3A and the clad part of the clad material 3B (that is, the x direction in FIG. 1) is It is longer than the length L2 of the surface of the second solidified portion 22.
This is because the heat conductivity of the first metal is as large as three times or more of the heat conductivity of the second metal, so that heat is transferred in the surface direction (the -z direction in FIG. 2) in the first metal layer 1. This is because it also extends in the horizontal direction (x direction and -x direction in FIG. 2). Since the surface is cooled, the first solidified portion 21 becomes maximum in the middle of the −z direction as shown in FIG. 1 and then decreases toward the surface (that is, FIG. 2). As shown in FIG. 1, the first solidified portion 21 has a barrel shape), but the length L1 is longer than the length L2. Whether such a first solidified portion 21 has a barrel shape and whether the length L1 is longer than the length L2 depends on the welding conditions, and is thus realized with all the obtained clad welding materials. is not. However, in many cases, the length L1 is longer than the length L2, which is a phenomenon that appears characteristically in the clad welding material obtained by the manufacturing method according to the present invention.

1. Clad material A clad rolled material of AZ61 magnesium alloy and industrial pure titanium (1 type) produced using the method described in Patent Document 1 was used. The thickness of the AZ61 magnesium alloy layer as the first metal layer 1 was 0.375 mm, and the thickness of the titanium layer as the second metal layer 2 was 0.125 mm (thus, the first metal layer 1 and the first metal layer 1 The ratio of the thicknesses of the two metal layers 2 was 3: 1, and the thickness of the clad material 3 was 0.5 mm).
From this clad rolled material, a plate of 50 mm in the rolling direction and 40 mm in the plate width direction was cut out to obtain the clad material 3 (3A, 3B). Rotating grindstone cutting (micro cut) was used for cutting the portion where the cut surface becomes the joint surface (welded surface). Moreover, about the part other than a joining surface, it performed by the shear which can be cut | disconnected simply.
The thermal conductivity of AZ61 magnesium alloy is 63.2 W · m ⁻¹ · K ⁻¹ (according to Int J Thermophys (2013) 34: 2343-2350. DOI 10.1007 / s10765-011-1145-1). The thermal conductivity of seed pure titanium is 16 W · m ⁻¹ · K ⁻¹ (from Metals Handbook, 10th edition, Volume 2, Wrought Titanium and Titanium Alloys, p. 620, (ASM International 1990)).

2. Butt welding The clad material 3A and the clad material 3B were arranged so that the direction in which the clad material 3A and the clad material 3B are arranged and the rolling direction are perpendicular to each other. That is, the rolling direction was arranged so as to be parallel to the y direction in FIG. More specifically, the clad material 3A and the first metal layer 1 of the clad material 3B are in contact with each other so that the cut surfaces of the clad material 3A and the clad material 3B by the above-described rotating grindstone are in contact with each other. 3A and the 2nd metal layer 2 of the clad material 3B were arrange | positioned so that it might mutually contact.
Then, as shown in FIG. 1, a radiator (backing metal) 14 is brought into contact with the surface of the first metal layer 1 of the clad material 3A and the clad material 3B (the surface opposite to the joint surface with the second metal layer 2). I let you.
The radiator 14 was cooled by air cooling (natural cooling) or water cooling. In the case of air cooling, a copper plate having a length (y direction of FIG. 1) of 60 mm, a width (x direction of FIG. 1) of 60 mm, and a height (z direction of FIG. 1) of 3 mm was used as the radiator 14. In the case of water cooling, a copper block having a vertical (y direction of FIG. 1) of 300 mm, a horizontal (x direction of FIG. 1) of 20 mm, and a height (z direction of FIG. 1) of 20 mm is used as the radiator 14. Water cooling was performed by flowing 12 ° C. water through a water conduit having a diameter of 10 mm provided inside using a cooling water circulation device.
The radiator 14 used for air cooling and water cooling was fixed to a steel moving table via a steel jig. That is, the clad material 3A, the clad material 3B, and the heat radiator 14 were disposed on the moving table.

The clad materials 3A and 3B thus arranged were welded (butt welding) using the laser device 10. The laser beam 12 was applied to the second metal layer 2 of both the clad material 3A and the clad material 3B. That is, after aligning so that the approximate center of the irradiation spot of the laser beam 12 passes through the contact portion between the second metal layer 2 of the clad material 3A and the second metal layer 2 of the clad material 3B, the clad material 3A The irradiation spot was scanned in the direction of arrow A in FIG. 1 along the contact portion between the second metal layer 2 and the second metal layer 2 of the clad material 3B.
The used laser device 10 is a high-power semiconductor laser.
As shown in Table 1, samples were prepared by changing the spot size d1 of the laser beam to 1.5 mm, the laser output to 250 to 450 W, and the scanning speed of the laser beam 12 to 5 to 15 mm / second. The scanning speed of the laser beam 12 was realized by moving the moving base in the opposite direction to the arrow A in FIG.
Moreover, in order to suppress that a molten metal touches air | atmosphere at the time of welding also about any sample, argon gas was flowed into the welding part 20L / min as a shielding gas.

3. Evaluation of clad welding material (1) Appearance observation result The appearance after welding was confirmed by visual observation. The appearance was confirmed for the first metal layer 1 and the second metal layer 2 (that is, both surfaces of the clad welding material). The results are shown in Table 2. In Table 2, ◎ indicates that the surface of the solidified part (welded part) is welded in a smooth state, ○ indicates that the surface of the solidified part is rough and uneven, and △ indicates a part that is not welded Indicates that there is.
FIG. 3 shows the surface observation result of the sample of Example 9 as an example of the surface observation result. FIG. 3A shows the surface observation result of the second metal layer, and FIG. 3B shows the surface observation result of the first metal layer. In the sample of Example 9, the surface of the first solidified part 21 in the direction connecting the clad part of the clad material 3A and the clad part of the clad material 3B (that is, the horizontal direction in FIGS. 3A and 3B). Length L1 and the surface length L2 of the second solidified portion 22 were measured. L1 was 2.39 mm, L2 was 2.35 mm, and L1 was longer than L2. In addition, this is an average value of the values measured at three places where the weld bead is clean. L1 and L2 are measured at three or more (preferably five or more), and it is preferable in terms of accuracy to use an average value.

(2) Tensile test After a tensile test piece was cut out from each obtained clad welding material sample using an electric discharge machine, a tensile test was performed using these tensile test pieces, and 0.2% of each sample Yield strength and tensile strength were determined. A tensile test was performed in a direction (TD) perpendicular to the rolling direction (RD) of the clad material at a strain rate of 1.67 × 10 ⁻³ / sec in the air at room temperature. Each sample was tested three times and the average value was calculated.
FIG. 4 is a plan view showing the shape of the tensile test piece used. Table 3 shows the tensile test results. Table 3 also shows the tensile test results of the clad material 3 before welding for comparison.

From Table 3, the 0.2% proof stress and tensile strength of the samples (Examples 7 to 13) in which the radiator 14 is water-cooled are generally higher than the samples in which the radiator 14 is air-cooled (Examples 1 to 6). In addition, there was a tendency for data variation to be small.
The reason for this is that the water cooling can more effectively cool the magnesium alloy layer (first metal layer) 1 and can more reliably suppress the vaporization of magnesium or the magnesium alloy, and the water cooling can melt the first metal. (Magnesium alloy) and the second metal (titanium) both have a high cooling rate during solidification, and it is considered that the crystal grains became finer than in the case of air cooling.

Among the samples in which the radiator 14 was air-cooled, the laser output was 400 W and the scanning speed of 5 mm / second was particularly high in Example 4, and in the samples in which the radiator 14 was water-cooled, the laser output was 400 W and the scanning speed. The Example 9 sample at 5 mm / sec and the Example 12 sample at a laser output of 450 W and a scanning speed of 10 mm / sec showed high intensity.
In these three samples showing high strength, the joint efficiency shows a sufficiently high value of 0.75 to 0.82 for 0.2% proof stress, and the joint efficiency is 0.64 to 0.68 for tensile strength. It is a sufficiently high value.

Moreover, since the strength of the welded portion was lower than the strength of the base material (clad material before welding), the tensile test fracture occurred in the welded portion in all samples. Therefore, while the clad material before welding had an elongation of 13.5% by tensile in the TD direction, the clad weld material had the largest elongation. Example 4 (The radiator was air-cooled, the laser output was Was 400 W and the scanning speed was 5 mm / second). However, this is because the parallel part of the tensile test piece is 10 mm, and the clad material before welding causes uniform elongation over the entire parallel part (length 10 mm), whereas the clad weld material corresponds to the laser spot size. This is because deformation concentrates on the region (about 1.5 mm in length). Therefore, an elongation corresponding to 1.4% × 10 mm / 1.5 mm≈9.3% actually occurs in the welded portion of the clad welding material having a relatively large elongation. That is, it can be seen that 13.5% of the base material exhibits practically sufficient ductility.
From the above results, it is preferable that the radiator is water-cooled when the strength is more important and the radiator is air-cooled when the ductility is more important.

(3) Cross section of weld zone The cross section of the weld zone was observed with an optical microscope. After cutting the cross section using a rotating grindstone cutting (micro cut), polishing to # 2000 with water-resistant emery paper, and buffing using 1.0 μm and 0.25 μm diamond paste for cross section observation A sample was obtained.
FIG. 5 shows a cross-sectional photograph of a typical weld. 5 (a) shows a cross section of the sample of Example 4, FIG. 5 (b) shows a cross section of the sample of Example 5, FIG. 5 (c) shows a cross section of the sample of Example 9, and FIG. Shows the cross section of the sample of Example 10, and FIG. 5E shows the cross section of the sample of Example 12.

In any of the embodiments, the first solidified part 21 that connects the first metal layer 1 of the clad part of the clad material 3A and the first metal layer 1 of the clad part of the clad material 3B and the second of the clad part of the clad material 3A. A second solidified portion 22 connecting the metal layer 2 and the second metal layer 2 of the clad portion of the clad material 3B was observed.
That is, a structure corresponding to the clad was also confirmed at the weld.
In the sample in which the radiator 14 is air-cooled, voids tend to exist in the first solidified portion (magnesium alloy) 21 in the vicinity of the second solidified portion (titanium) 22, whereas in the sample in which the radiator 14 is water-cooled, Almost never occurred.
In addition, when the radiator 14 is air-cooled, relatively large dents are generated in two lower portions of the first solidified portion 21. This is presumably because the molten magnesium alloy was vaporized to some extent due to further temperature rise.
From the above results, it can be seen that the first solidified portion 21 is obtained when the radiator 14 is water-cooled.

DESCRIPTION OF SYMBOLS 1 1st metal layer 2 2nd metal layer 3, 3A, 3B Clad material 10 Laser apparatus 12 Laser beam 14 Radiator 21 1st solidification part 22 2nd solidification part 23 Solidification part

Claims (8)

1) A first metal layer made of a first metal, and a second metal layer made of a second metal having a melting point higher than that of the first metal by 800 ° C. and a thermal conductivity of less than one third. A step of arranging two opposite ends of the clad clad material,
2) While cooling the surface of the first metal layer, a part of the surface of the second metal layer is irradiated with a laser to melt a part of the second metal layer of at least one of the two end portions. And melting a part of at least one of the first metal layers at the two end portions by heat transfer from the second metal;
3) forming a solidified portion that connects the unmelted portions of the two end portions by solidifying the molten first metal and the molten second metal;
The manufacturing method of the clad welding material characterized by including.   In the step 3), the solidified portion is composed of a first metal, and is composed of a first solidified portion connecting a first metal layer of an unmelted portion of each of the two ends, and a second metal, 2. The method for manufacturing a clad welding material according to claim 1, further comprising: a second solidified portion that connects the second metal layers of the unmelted portions of the two end portions.   The clad according to claim 1 or 2, wherein the first metal is magnesium or a magnesium alloy, and the second metal is any one selected from titanium, a titanium alloy, iron, and an iron alloy. Manufacturing method of welding material.   The cladding welding material according to any one of claims 1 to 3, wherein the cooling of the first metal layer in the step 2) is performed by bringing a radiator into contact with the first metal layer. Manufacturing method. The method for manufacturing a clad welding material according to claim 4 , wherein the radiator is cooled by a liquid.   The method for manufacturing a clad welding material according to claim 4 or 5, wherein the heat dissipating body is made of a metal having a thermal conductivity larger than that of the first metal. The first metal layer made of the first metal and the second metal layer made of the second metal having a melting point higher than that of the first metal by 800 ° C. and a thermal conductivity of not more than one third were clad. A cladding part;
Connecting between the two clad parts, a solidified part having a solidified structure ;
Including
The solidified portion connects the first metal layer of each of the two clad portions, connects the first solidified portion made of the first metal, and the second metal layer of each of the two clad portions, and A second solidified portion made of two metals,
The first metal is magnesium or a magnesium alloy, and the second metal is any one selected from titanium, a titanium alloy, iron, and an iron alloy;
The first metal layer is thicker than the second metal layer,
A clad welding material, wherein a length of a surface of the first solidified portion is longer than a length of a surface of the second solidified portion in a direction connecting the two clad portions. The clad welding material according to claim 7, wherein the first solidified portion and the second solidified portion do not contain an intermetallic compound.