Clad materials and manufacturing methods

Abstract

To provide clad materials with excellent creep resistance and manufacturing methods therefor.SOLUTION: A clad material according to the present invention is a clad material comprising a core material and a skin material covering the core material, where the skin material has an average crystal grain size of 250 μm or more and a KAM value of 1.0 or less as calculated based on the backscattered electron diffraction method.SELECTED DRAWING: Figure 1

Description

Technical Field

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[0001] The present invention relates to a clad material and a manufacturing method thereof.

Background Art

[0002] Conventionally, due to the demand for weight reduction of members in the entire industrial field, weight reduction of members for processing has been attempted from various viewpoints. On the other hand, it is also necessary to improve the reliability and durability of products, and the coexistence of these has become necessary. To achieve this coexistence, a technique of combining two types of materials to produce a member for processing has been spreading. For example, Patent Document 1 describes a wire material (hereinafter also referred to as a clad material) having a core material and a skin material covering the surface of the core material.

[0003] Patent Document 1 discloses a clad material produced by using a hydrostatic extrusion method. In the hydrostatic extrusion method, a clad material is produced by extruding a billet in which a core material and a skin material are assembled in advance.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0007] To solve the above-mentioned problems and achieve the objective, the clad material according to the present invention is a clad material comprising a core material and a shell material covering the core material, wherein the shell material has an average grain size of 250 μm or more and a KAM value calculated based on backscattered electron diffraction of 1.0 or less.

[0008] Furthermore, the present invention relates to a manufacturing method for producing a clad material having a core material and a cladding material that covers the core material, and is characterized by comprising: a core material heating step of heating the core material; a roll casting step of passing the heat-treated core material and the liquid cladding material through a space formed by grooves of a plurality of disc-shaped rolls, each having grooves on a part of its side surface, to coat the surface of the core material with the cladding material; and a solution heating step of performing solution heating on the molded product produced by the roll casting step.

[0009] Furthermore, the manufacturing method according to the present invention is characterized in that, in the above invention, it further includes an aging heating step in which aging heating is performed on the molded product after the solution heating step. [Effects of the Invention]

[0010] The present invention provides the effect of obtaining a clad material with excellent creep resistance. [Brief explanation of the drawing]

[0011] [Figure 1] Figure 1 is a perspective view showing the configuration of the clad material according to Embodiment 1 of the present invention. [Figure 2] Figure 2 is a flowchart showing a method for manufacturing clad material according to Embodiment 1 of the present invention. [Figure 3]Figure 3 is a cross-sectional view showing the configuration of a clad material manufacturing apparatus according to Embodiment 1 of the present invention. [Figure 4] Figure 4 shows the configuration of the main parts of the clad material manufacturing apparatus according to Embodiment 1 of the present invention. [Figure 5] Figure 5 shows the orientation distribution of the clad material after heat treatment at 540°C. [Figure 6] Figure 6 shows the orientation distribution of the clad material after heat treatment at 520°C. [Figure 7] Figure 7 shows the orientation distribution of the clad material after heat treatment at 500°C. [Figure 8] Figure 8 shows the orientation distribution of the clad material after heat treatment at 480°C. [Figure 9] Figure 9 shows the strain distribution of the clad material after heat treatment at 540°C. [Figure 10] Figure 10 shows the strain distribution of the clad material after heat treatment at 520°C. [Figure 11] Figure 11 shows the strain distribution of the clad material after heat treatment at 500°C. [Figure 12] Figure 12 shows the strain distribution of the clad material after heat treatment at 480°C. [Figure 13] Figure 13 is a diagram (part 1) showing the orientation distribution (a) and strain distribution (b) of a clad material produced by a hydrostatic extrusion method after heat treatment at 540°C. [Figure 14] Figure 14 is a diagram (part 2) showing the orientation distribution (a) and strain distribution (b) of a clad material produced by a hydrostatic extrusion method after heat treatment at 540°C. [Figure 15] Figure 15 is a diagram (part 3) showing the orientation distribution (a) and strain distribution (b) of a clad material produced by a hydrostatic extrusion method after heat treatment at 540°C. [Figure 16] Figure 16 is a flowchart showing a method for manufacturing clad material according to a modified example of Embodiment 1 of the present invention. [Figure 17]FIG. 17 is a perspective view showing the configuration of the clad material manufacturing apparatus according to Embodiment 2 of the present invention. [Figure 18] FIG. 18 is a cross-sectional view showing the configuration of the clad material manufacturing apparatus according to Embodiment 2 of the present invention. [Figure 19] FIG. 19 is a cross-sectional view corresponding to the Q-Q line shown in FIG. 18. [Figure 20] FIG. 20 is a diagram for explaining the positional relationship between two rolls and four rolls. [Figure 21] FIG. 21 is a cross-sectional view for explaining the configuration of the main part of the clad material manufacturing apparatus and the configuration of the wire rod according to a modified example of Embodiment 2 of the present invention.

Embodiments for Carrying Out the Invention

[0012] Hereinafter, embodiments for carrying out the present invention will be described in detail with reference to the drawings. Note that the present invention is not limited by the following embodiments. Also, each drawing referred to in the following description only schematically shows the shape, size, and positional relationship to the extent that the content of the present invention can be understood. That is, the present invention is not limited only to the shape, size, and positional relationship illustrated in each drawing.

[0013] (Embodiment 1) FIG. 1 is a perspective view showing the configuration of the clad material according to Embodiment 1 of the present invention. The clad material 1 includes a core material 2 and a skin material 3 that covers the core material 2.

[0014] The core material 2 is a columnar member formed using a first metal material. Examples of the first metal material include metals and alloys such as aluminum, aluminum alloy, zinc, zinc alloy, tin, tin alloy, magnesium, magnesium alloy, copper, copper alloy, iron, iron alloy, steel, titanium, or titanium alloy. Here, for example, an aluminum alloy is an alloy having aluminum as a main component.

[0015] The outer layer 3 is a cylindrical member formed using a second metallic material. The second metallic material can be a metal or alloy such as aluminum, aluminum alloy, magnesium, or magnesium alloy. The outer layer 3 is made of a metallic material with different properties than the core material 2. The outer layer 3 has an average grain size of 250 μm or more, obtained by electron backscatter diffraction (EBSD), and a KAM (Kernel Average Misorientation) value of 1.0 or less calculated based on the EBSD method. More preferably, the average grain size is 250 μm or more and 600 μm or less, and the KAM value calculated based on the EBSD method is 0.3 or more and 1.0 or less.

[0016] Next, a method for manufacturing the clad material 1 will be described. Figure 2 is a flowchart showing a method for manufacturing the clad material according to Embodiment 1 of the present invention. A core material 2 is prepared and heated (Step S101: Core material heating step). In the core material heating treatment, the core material 2 is heated to a temperature at which the core material 2 and the outer material 3 can be sufficiently bonded. In this Embodiment 1, the heating temperature is, for example, 350°C or higher when aluminum is used. For the core material heating treatment, known methods such as atmospheric furnace heating treatment, high-frequency induction heating treatment, resistance heating treatment, and infrared heating treatment can be used.

[0017] After heating the core material 2, a molded product is produced by covering the core material 2 with the outer material 3 using a roll casting process (Step S102: Roll Casting Step). The roll casting process will be described later.

[0018] After roll casting, the resulting molded product is subjected to solution heat treatment (Step S103: Molded product heating step). In this solution heat treatment, the molded product is heated at a temperature set within the temperature range for solution treatment. Solution treatment allows the additive elements to dissolve into the base material of the molded product. By performing heat treatment at the solution treatment temperature, the recrystallization of the structure of the outer layer 3 is promoted. This solution heat treatment is set, for example, within a temperature range of 500°C or higher and below the melting point. Specifically, when using aluminum alloy A2618, the recommended temperature for solution treatment is generally said to be 525°C to 535°C. When using aluminum alloy A6063, the recommended temperature for solution treatment is generally said to be 515°C to 525°C.

[0019] After solution heat treatment, the molded product is subjected to finishing processes to produce clad material 1 (step S104). The finishing processes include drawing to achieve the desired diameter, deburring, cutting to a predetermined length, and surface treatments such as polishing.

[0020] Next, the roll casting process in step S102 will be described with reference to Figures 3 and 4. Figure 3 is a cross-sectional view showing the configuration of a clad material manufacturing apparatus according to Embodiment 1 of the present invention. Figure 4 is a diagram showing the configuration of the main parts of the clad material manufacturing apparatus according to Embodiment 1 of the present invention. Figure 4 is a view of the roll member and clad material shown in Figure 3, seen from below Figure 3.

[0021] The manufacturing apparatus 100 shown in Figure 3 is an apparatus used for roll casting. The manufacturing apparatus 100 comprises a roll member 110, a guide member 120, and a protective tube 130.

[0022] The roll member 110 has a first roll 111 and a second roll 112. Both the first roll 111 and the second roll 112 are disc-shaped and are arranged with their sides facing each other. The materials of the first roll 111 and the second roll 112 can be steel, copper, copper alloy, tungsten-based alloy, superalloy, or cemented carbide. A film can be formed on the surface of these metal materials to suppress the reaction between the liquid 30 and the rolls. For example, ceramic coatings such as titanium aluminum nitride and chromium nitride, or amorphous carbon films can be used for the coating. Furthermore, to further reduce the reaction between the liquid 30 and the rolls, ceramics such as silicon nitride, alumina, and zirconia can be used for the materials of the first roll 111 and the second roll 112. In addition, the materials of the first roll 111 and the second roll 112 may be the same or different.

[0023] The first roll 111 is rotatable around a first axis 113 that extends in the thickness direction of the roll and passes through the center of the main surface of the roll. The second roll 112 is also rotatable around a second axis 114 that extends in the thickness direction of the roll and passes through the center of the roll. The first roll 111 and the second roll 112 rotate in opposite directions and in the direction of drawing the core material 2 out from the guide member 120.

[0024] A concave first groove 111a is formed on the side surface of the first roll 111 (see Figure 4). Similarly, a concave second groove 112a is formed on the side surface of the second roll 112. Both the first groove 111a and the second groove 112a are formed by cutting out a semicircular portion of the side surface and have groove surfaces that extend in an arc shape. When the sides of the first roll 111 and the second roll 112 are in contact with each other, excluding the grooves, the grooves face each other to form a circular space P1. The space P1 is the same size as the cladding material 3 of the cladding material 1. For example, the space P1 forms a circle with a diameter the same as the cladding material 3. Note that the "groove surface" corresponds to the wall surface that forms the groove on the side surface of each roll. The first roll 111 and the second roll 112 may have the same shape as each other, or they may have different shapes (for example, different diameters), as long as they can form a space P1.

[0025] The guide member 120 has a tapered tip shape and forms an internal space that penetrates from the tip to the end opposite the tip. The tip of the guide member 120 is positioned between the first roll 111 and the second roll 112. Liquid 30, in which the leather material 3 has been melted by heating, is poured into the guide member 120, for example using a container 140. The guide member 120 guides the core material 2 and the liquid 30 into the space P1 formed by the first roll 111 and the second roll 112. The order in which the core material 2 and liquid 30 are guided from the guide member 120 to the space P1 is as follows: the guide of the core material 2 may be started first while the liquid 30 is poured in; the liquid 30 may be poured in first and then the core material 2 may be guided; or the core material 2 and liquid 30 may be poured in simultaneously.

[0026] The protective tube 130 is cylindrical, with a portion of it located inside the guide member 120. In the cross-section of the protective tube 130, the inner circumferential surface is circular. The size of this inner circumferential surface circle is larger than the diameter of the outer circumference of the core material 2. The central axis of the tube 130 passes through the center of the circular space P1 formed by the first groove 111a and the second groove 112a. The protective tube 130 is fixed in position relative to the guide member 120 by a fixing member (not shown). The protective tube 130 guides the core material 2 into the space P1 formed by the first roll 111 and the second roll 112. The protective tube 130 corresponds to the second guide member.

[0027] In the roll casting process, both the core material 2 and the liquid 30 move from the guide member 120 side to the roll side and pass through the space P1. At this time, the liquid 30 is poured into the guide member 120 and solidifies due to a decrease in temperature as it passes through the space P1. This decrease in temperature is cooled by heat dissipation through contact with the surfaces of the first roll 111 and the second roll 112, and the surface of the core material 2, resulting in the molded product (skin material 3) described above.

[0028] Here, the average grain size and KAM value of the clad material after heat treatment will be explained with reference to Figures 5 to 22. Here, the average grain size is calculated based on the diffraction pattern (crystal orientation distribution) measured by, for example, EBSD analysis. The KAM value is calculated based on, for example, EBSD analysis and represents the average value of the orientation difference between adjacent measurement points. The clad material used here is an aluminum alloy A2618 as the core material and A6063 as the outer layer. This clad material undergoes solution formation (complete recrystallization) above 500°C, partial solution formation (recrystallization) at 480°C, and no solution formation (non-recrystallization) at temperatures below 480°C.

[0029] Specifically, the average grain size and KAM value are measured under the following conditions. Measuring device: JEOL JSM-7000F Measurement range: The range of images shown in Figures 5 to 15. This invention: 1700 μm × 750 μm Hydrostatic extruded material: 200 μm × 700 μm Measurement step size: 2.0 μm Analysis software: OIM Analysis ver7, manufactured by TSL Solutions Inc. Calculation method: (Average grain size) In the outer material (excluding the core material) within the above measurement range, the average grain boundary was calculated by defining the boundary with an orientation angle difference of 5° or more as the grain boundary. (KAM value) The KAM value was determined at each measurement point of the outer material (excluding the core material) within the above measurement range, and these values ​​were arithmetic mean to obtain the KAM value.

[0030] Figure 5 shows the orientation distribution of the clad material after heat treatment at 540°C. Figure 6 shows the orientation distribution of the clad material after heat treatment at 520°C. Figure 7 shows the orientation distribution of the clad material after heat treatment at 500°C. Figure 8 shows the orientation distribution of the clad material after heat treatment at 480°C. Figures 5 to 8 show the orientation distribution obtained by EBSD analysis for clad materials heat-treated at each heating temperature. In Figures 5 to 8, the lower layer is the layer of the outer layer 3.

[0031] The average grain size of the outer layer, determined from the orientation distribution shown in Figure 5 (heating temperature 540°C), was 535 μm. The average grain size of the outer layer, determined from the orientation distribution shown in Figure 6 (heating temperature 520°C), was 286 μm. The average grain size of the outer layer, determined from the orientation distribution shown in Figure 7 (heating temperature 500°C), was 332 μm. The average grain size of the outer layer, determined from the orientation distribution shown in Figure 8 (heating temperature 480°C), was 146 μm.

[0032] Figure 9 shows the strain distribution of the clad material after heat treatment at 540°C. Figure 10 shows the strain distribution of the clad material after heat treatment at 520°C. Figure 11 shows the strain distribution of the clad material after heat treatment at 500°C. Figure 12 shows the strain distribution of the clad material after heat treatment at 480°C. Figures 9 to 12 show the strain distribution obtained by EBSD analysis for clad materials heat-treated at each heating temperature. In Figures 9 to 12, the lower layer is the layer of the outer layer 3. In the strain distributions shown in Figures 9 to 12, darker colors indicate smaller residual strain.

[0033] The KAM value of the leather material, determined from the strain distribution shown in Figure 9 (heating temperature 540°C), was 0.59. The KAM value of the leather material, determined from the strain distribution shown in Figure 10 (heating temperature 520°C), was 0.60. The KAM value of the leather material, determined from the strain distribution shown in Figure 11 (heating temperature 500°C), was 0.65. The KAM value of the leather material, determined from the strain distribution shown in Figure 12 (heating temperature 480°C), was 1.38.

[0034] Figures 13 to 15 show the orientation distribution (a) and strain distribution (b) of a clad material produced by hydrostatic extrusion after heat treatment at 540°C. In Figures 13 to 15, the upper layer is the outer layer 3. Comparing Figures 13 to 15 with Figure 5, it can be seen that the average grain size of the clad material produced by hydrostatic extrusion is smaller than the average grain size of the clad material produced by the treatment according to this embodiment. Basically, the higher the heat treatment temperature, the larger the average crystal grain size, so even in clad materials produced by hydrostatic extrusion, the average crystal grain size is smaller at temperatures below 540°C.

[0035] The KAM value of the leather material, determined from the strain distribution shown in Figure 13, was 0.38. The KAM value of the leather material, determined from the strain distribution shown in Figure 14, was 0.33. The KAM value of the leather material, determined from the strain distribution shown in Figure 15, was 0.41.

[0036] As shown in Figures 5 to 7, when the outer layer 3 was formed by roll casting and heat-treated at 500°C to 540°C, the average grain size of the resulting crystals was between 286 μm and 535 μm. In contrast, as shown in Figure 8, when the outer layer 3 was formed by roll casting and heat-treated at 480°C, the average grain size of the resulting outer layer was 146 μm. Furthermore, when the outer layer 3 was formed by hydrostatic extrusion and heat-treated at 500°C to 540°C, the average grain size of the resulting outer layer was, for example, 64 μm at 540°C. From this, it can be said that when the outer layer 3 is formed by roll casting and heat-treated at 500°C to 540°C, the average grain size is larger compared to when it is heat-treated at a temperature below 500°C or when the outer layer is formed by hydrostatic extrusion.

[0037] Furthermore, as shown in Figures 9 to 11, when the outer layer 3 was formed by roll casting and heat-treated at 500°C to 540°C, the KAM value of the resulting crystals was between 0.59 and 0.65. In contrast, as shown in Figure 12, when the outer layer 3 was formed by roll casting and heat-treated at 480°C, the KAM value of the resulting crystals was 1.38. Also, as shown in Figures 13 to 15, when the outer layer 3 was formed by hydrostatic extrusion and heat-treated at 540°C, the KAM value of the resulting crystals was between 0.33 and 0.41.

[0038] Here, the KAM value represents the magnitude of strain within the crystal grains; the smaller the KAM value, the smaller the strain within the crystal grains. Therefore, when the outer layer 3 is formed by roll casting and heat-treated at 500°C to 540°C, the KAM value is smaller and the strain within the crystal grains is smaller compared to when heat-treated at less than 500°C. Smaller strain results in smaller residual stress within the crystal. In particular, when the KAM value is 1 or less, it can be said that there is almost no residual strain.

[0039] As described above, in this embodiment 1, a clad material 1 is manufactured by passing a heat-treated core material 2 and a liquid 30 through a space P1 formed by two rolls, while solidifying the liquid 30, and then heat-treating it at a temperature of 500°C to 540°C. In this clad material 1, the average grain size of the outer material 3 is 250 μm or more, and the KAM value obtained by EBSD is 1.0 or less. Generally, metal materials are said to have better creep resistance the larger the grain size and the less residual strain they have, and the clad material 1 according to this embodiment 1 can be said to have excellent creep resistance.

[0040] Furthermore, in this embodiment 1, the clad material 1 is manufactured by passing a heat-treated core material 2 and a liquid 30 through a space P1 formed by two rolls, while the liquid 30 is solidified. According to this embodiment 1, since the liquid outer material 3 is brought into contact with the heated core material 2, a clad material 1 can be manufactured in which the core material 2 and the outer material 3 are joined with high bonding strength. In addition, according to this embodiment 1, the clad material can be manufactured with fewer work steps without joining separately manufactured core materials and outer materials, or by repeatedly performing annealing and drawing.

[0041] (Modified version of Embodiment 1) Next, a modified example of Embodiment 1 will be described with reference to Figure 16. Figure 16 is a flowchart showing a method for manufacturing clad material according to a modified example of Embodiment 1 of the present invention. In the manufacturing method according to the modified example, an aging heat treatment is performed between the solution heat treatment and the finishing treatment. The rest is the same as Embodiment 1 described above, so the explanation will be omitted.

[0042] In this modified example, the core material 2 is heated in the same manner as in steps S101 to S103 of Embodiment 1, and the molded product made by covering the core material 2 with the outer material 3 by roll casting is subjected to solution heat treatment (steps S201 to S203).

[0043] After solution heat treatment, the molded product is subjected to aging heat treatment (step S204: aging heat step). In the aging heat treatment, the temperature is raised again after the solution heat treatment. The temperature for the aging heat treatment is set to, for example, 100°C to 200°C, and is set appropriately depending on the material. Specifically, for example, for A2618 it is set to 195°C to 205°C for 20 hours, and for A6063 it is set to 205°C for 1 to 8 hours. The temperature for the aging heat treatment may also be set to room temperature.

[0044] After aging heat treatment, the molded product is subjected to a finishing process to produce clad material 1 (step S205).

[0045] In this modified example, the same effects as in Embodiment 1 can be obtained.

[0046] (Embodiment 2) Next, Embodiment 2 of the present invention will be described with reference to Figures 17 to 19. Figure 17 is a perspective view showing the configuration of a clad material manufacturing apparatus according to Embodiment 2 of the present invention. Figure 18 is a cross-sectional view showing the configuration of a clad material manufacturing apparatus according to Embodiment 2 of the present invention. Figure 19 is a cross-sectional view corresponding to the QQ line shown in Figure 18.

[0047] The manufacturing apparatus 100A according to Embodiment 2 comprises a roll member 110A, a guide member 120A, and a protective tube 130.

[0048] The roll member 110A has a first roll 115, a second roll 116, a third roll 117, and a fourth roll 118. The first to fourth rolls 115 to 118 are each disc-shaped and are arranged with their sides facing each other. The first to fourth rolls 118 are arranged at equal intervals with respect to the guide member 120A, for example, the first roll 115 is oriented 90° relative to the adjacent second roll 116 and fourth roll 118. The first roll 115 is rotatable about an axis N1 that extends in the thickness direction of the roll and passes through the center of the roll. The second roll 116 is rotatable about an axis N2 that extends in the thickness direction of the roll and passes through the center of the roll. The third roll 117 is rotatable about an axis N3 that extends in the thickness direction of the roll and passes through the center of the roll. The fourth roll 118 extends in the thickness direction of the roll and is rotatable about an axis (not shown) that passes through the center of the roll.

[0049] The materials of the first roll 115 to the fourth roll 118 can be steel, copper, copper alloy, tungsten-based alloy, superalloy, or cemented carbide. A coating can be formed on the surface of these metal materials to suppress the reaction between the liquid 30 and the rolls. For example, ceramic coatings such as titanium aluminum nitride and chromium nitride, or amorphous carbon films can be used for the coating. Furthermore, to further reduce the reaction between the liquid 30 and the rolls, ceramics such as silicon nitride, alumina, and zirconia can be used for the first roll 115 to the fourth roll 118. In addition, the materials of the first roll 115 to the fourth roll 118 may be the same as each other, may be different from each other, or may be partially different from other materials.

[0050] A concave first groove 115a is formed on the side surface of the first roll 115 (see Figure 18). A concave second groove 116a is formed on the side surface of the second roll 116. A concave third groove 117a is formed on the side surface of the third roll 117. A concave fourth groove 118a is formed on the side surface of the fourth roll 118. The first grooves 115a to the fourth grooves 118a are each notched in an arc shape, and the opposing grooves form a circular space P2. The first roll 115 to the fourth roll 118 may have the same shape as each other, or they may have different shapes (for example, different diameters), as long as they can form space P2.

[0051] The guide member 120A has a tapered tip shape and a main body portion 121 that forms an internal space penetrating the tip and the end opposite the tip, and a clamping portion 122 provided on the outer circumference of the main body portion 121 that clamps the first roll 115 to the fourth roll 118. Liquid 30 in which the leather material 3 is dissolved is poured into the guide member 120A using a container 140 (see Figure 19). The guide member 120A guides the core material 2A and the liquid 30 into the space P2 formed by the first roll 115 to the fourth roll 118. The guide member 120A may be made by combining multiple members, or it may be made as a single, integrated member.

[0052] The protective tube 130 is cylindrical, with a portion of it located inside the guide member 120A. The central axis of the protective tube 130 passes through the center of the circular space P2 formed by the first groove 115a to the fourth groove 118a. The protective tube 130 guides the core material 2 into the space P2 formed by the first roll 111 and the second roll 112.

[0053] In the roll casting process, similar to Embodiment 1, the heated core material 2 and liquid 30 both move from the guide member 120A side to the roll side and pass through space P2. At this time, the liquid 30 is poured into the guide member 120A and then passes through space P2 while solidifying. The liquid 30 solidifies near the surface of the core material 2 and the surfaces of the first roll 115 to the fourth roll 118, becoming the cladding material 3. This produces a molded product. Subsequently, by subjecting this molded product to heat treatment, a cladding material having the same average grain size and KAM value as in Embodiment 1 is obtained.

[0054] As described above, in this embodiment 2, a clad material 1 is produced by passing a heat-treated core material 2 and a liquid 30 through a space P2 formed by four rolls, while solidifying the liquid 30. Then, by heat treatment at a temperature of 500°C to 540°C, a clad material is obtained in which the average grain size of the outer material 3 is 250 μm to 600 μm and the KAM value obtained by EBSD is 0.3 to 1.0. According to this embodiment 2, similar to embodiment 1, the obtained clad material can be said to have excellent creep resistance.

[0055] Here, the number of rolls and their relative positions will be explained with reference to Figure 20. Figure 20 is a diagram illustrating the contact state between two rolls and four rolls. Figure 20 shows the relative positions of two rolls. For four rolls, refer to Figure 19. Here, a larger number of rolls improves the uniformity of the roll pressure on the core material 2, thereby suppressing the generation of burrs on the outer surface of the outer material 3 during manufacturing and the formation of gaps between the core material 2 and the outer material 3.

[0056] (Modified version of Embodiment 2) Next, a modified example of Embodiment 2 will be described with reference to Figure 21. Figure 21 is a cross-sectional view illustrating the configuration of the main parts of a clad material manufacturing apparatus and the configuration of wire according to a modified example of Embodiment 2 of the present invention. The clad material 1A according to the modified example comprises a prismatic core material 2A and a skin material 3A that covers the core material 2A. In addition, grooves corresponding to the clad material are formed on the rollers used in the roll casting process. The other configurations are the same as those of Embodiment 2 described above, so their description will be omitted.

[0057] In this modified example, a V-shaped first groove 115b is formed on the side surface of the first roll 115. A V-shaped second groove 116b is formed on the side surface of the second roll 116. A V-shaped third groove 117b is formed on the side surface of the third roll 117. A V-shaped fourth groove 118b is formed on the side surface of the fourth roll 118. Each of the first grooves 115b to the fourth groove 118b is formed by two inclined surfaces extending in the circumferential direction, and the angle between these two inclined surfaces is 90°. The first grooves 115b to the fourth groove 118b face each other to form a rectangular (square) space P3.

[0058] In the roll casting process, similar to Embodiment 2, both the core material 2A and the liquid 30 move from the guide member 120A side to the roll side and pass through space P3. As they pass through space P3, the liquid 30 solidifies near the surface of the core material 2A and the surfaces of the first roll 115 to the fourth roll 118, becoming the cladding material 3A. This produces the molded product according to this modified example. Subsequently, by subjecting this molded product to heat treatment, a cladding material having the same average grain size and KAM value as Embodiment 1 is obtained.

[0059] As described above, in this modified example, the clad material is produced by passing the core material 2A and the liquid 30 through the space P3 formed by the four rolls, while the liquid 30 is solidified, so the same effects as in Embodiment 2 can be obtained.

[0060] In the embodiments described above, examples were given where the space formed between the rolls was a circle or a rectangle. However, other shapes such as ellipses, trapezoids, polygons with pentagons or more, or star shapes may also be used. Furthermore, the number of rolls is not limited to two or four. From the viewpoint of suppressing the generation of burrs on the outer surface of the skin material 3 and the formation of gaps between the core material 2 and the skin material 3, it is preferable to have three or more rolls. Moreover, the shapes of the core material and the skin material may differ in cross-section. For example, a skin material with a circular outer edge may be used to cover a core material with a rectangular cross-section. In this case, it is possible to manufacture the product by passing the core material with a rectangular cross-section through the manufacturing apparatus 100.

[0061] Thus, the present invention may include various embodiments not described herein, and various design modifications can be made without departing from the technical idea specified by the claims.

[0062] As described above, the clad material and manufacturing method according to the present invention are suitable as clad materials with excellent creep resistance. [Explanation of symbols]

[0063] 1. 1A clad material 2, 2A core material 3, 3A leather material 100, 100A manufacturing equipment 110, 110A Roll Member 111, 115 First Roll 111a, 115a 1st groove 112, 116, 2nd roll 112a, 116a 2nd groove 113 1st axis 114 2nd axis 117 Roll 3 117a 3rd groove 118 Roll 4 118a 4th groove 120, 120A Guide Member 121 Main body 122 Clamping part 130 protective tube 140 containers

Claims

1. A columnar core material, A skin material covering the core material, Clad material equipped with, The aforementioned outer material covers the entire circumference of the side surface of the core material around the axis extending in the longitudinal direction of the core material, has an average crystal grain size of 250 μm or more, and a KAM value calculated based on backscattered electron diffraction of 1.0 or less. A clad material characterized by the following features.

2. A method for manufacturing a clad material having a core material and a covering material for the core material, A core material heating step for heating the core material, A roll casting step in which a heat-treated core material and liquid leather material are passed through a space formed by grooves of a plurality of disc-shaped rolls, each having grooves formed on a part of its side surface, thereby coating the surface of the core material with the leather material, A solution heating step is performed on the molded product produced by the roll casting step, by performing solution heating at a temperature of 500°C or higher. A manufacturing method characterized by including the following.

3. A aging heating step is performed on the molded product after the solution heating step. The manufacturing method according to claim 2, further comprising:

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