Metal molded products

Abstract

To provide a metal molded article capable of improving strength without increasing thickness and simultaneously achieving further weight reduction.SOLUTION: A metal molded article 10 according to the present embodiment is formed of a clad material 12 including a first layer 21 and a second layer 22, and includes a bent portion 11. In an observation region 30, an interface 24 and a surface 23 appearing therein are defined as an interface line 31 and a surface line 32, respectively. A first virtual line 61 is included in a first range 41 that is set at a distance up to 50 μm from the interface line 31 toward the surface 23 side, and is a line equidistant from the interface line 31. A second virtual line 62 is included in a second range 42 that is set at a distance up to 100 μm from the surface line 32 toward the interface 24 side, and is a line equidistant from the interface line 24. In this case, a first value X, which is the number of crystal grain boundaries of the first layer 21 which the first virtual line 61 intersects within the first range 41, and a second value Y, which is the number of crystal grain boundaries of the first layer 21 which the second virtual line 62 intersects within the second range 42, satisfy the relationship of 1.1≤Y / X≤5.0.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present embodiment relates to a metal molded product using a clad material. [Background technology]

[0002] Traditionally, metal molded products, such as container bodies and lids, have primarily been made of Fe-based materials such as steel and stainless steel to ensure high strength. However, increasing the wall thickness of metal molded products to increase strength results in increased mass. Therefore, metal molded products are required to ensure high strength without increasing mass. For example, if an Al-based material is used instead of an Fe-based material to reduce weight, an increased wall thickness is required to ensure the same strength as the Fe-based material. However, increased wall thickness can cause interference with surrounding components, reducing design and assembly flexibility. Furthermore, when using Fe-based materials to reduce weight, the wall thickness must be reduced, resulting in a decrease in strength. Furthermore, using Fe-based materials that offer high strength without increasing wall thickness is expensive and has poor processability compared to conventional materials. Thus, materials for metal molded products must achieve both strength and light weight.

[0003] From the viewpoint of achieving both high strength and light weight, clad materials made by laminating two or more types of metal are known. These clad materials are used as metal molded products such as container bodies and lids. As a clad material that achieves both strength and light weight, for example, a laminate of an Al-based material and an Fe-based material is used (see Patent Document 1).

[0004] However, in recent years, there has been a demand for further reduction in energy consumption, for example in vehicles, etc. Therefore, metal molded products used as parts are also required to achieve a high level of both strength and weight reduction, i.e., to maintain strength while further reducing weight. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 8-39269 Summary of the Invention [Problem to be solved by the invention]

[0006] Therefore, an object of the present invention is to provide a metal molded product that can be made even lighter without increasing its thickness and has improved strength. [Means for solving the problem]

[0007] In order to solve the above problems, the metal molded product of this embodiment is formed of a clad material and has a bent portion. The clad material includes a first layer and a second layer. The first layer is formed of an Al-based material and has a surface located inside the bent portion. The second layer is formed of an Fe-based material and is laminated on the outside of the first layer at the bent portion, forming an interface at the boundary with the first layer. In an observation area arbitrarily set on a cross section of the clad material along the thickness direction at the bent portion, the interface appearing in the observation area is defined as an interface line, and the surface appearing in the observation area is defined as a surface line. In the first layer, a line within a first range set at a distance of 50 μm from the interface line toward the surface and equidistant from the interface line is defined as a first virtual line. In the first layer, a line within a second range set at a distance of 100 μm from the surface line toward the interface and equidistant from the interface line is defined as a second virtual line. In this case, the relationship 1.1≦Y / X≦5.0 is satisfied between a first value X, which is the number of grain boundaries of the first layer that the first virtual line intersects in the first range, and a second value Y, which is the number of grain boundaries of the first layer that the second virtual line intersects in the second range.

[0008] In this way, the number of crystal grains in the first layer located inside the bent portion of the clad material differs between the surface side and the interface side closer to the second layer. Specifically, the Y / X ratio of the first layer is controlled based on the number of grain boundaries in the bent portion. This results in the crystal grains in the first layer being finer on the surface side of the bent portion than on the interface side. Therefore, the hardness of the surface side of the first layer is improved compared to the interface side of the bent portion. Therefore, even when further weight reduction is desired, the overall strength can be increased without increasing the thickness of the clad material. [Brief explanation of the drawings]

[0009] [Figure 1] Enlarged cross-sectional view of part I in Figure 2 [Figure 2] Schematic diagram showing a metal molded product according to one embodiment. [Figure 3] 1 is a schematic diagram showing the structure of a material in an observation area of ​​a metal molded product according to an embodiment; [Figure 4] FIG. 2 is a cross-sectional view corresponding to FIG. 1, illustrating a modified example of the metal molded product according to the embodiment. [Figure 5] Schematic diagram showing an outline of a strength test for a metal molded product according to one embodiment. [Figure 6] Schematic diagrams showing test results of examples and comparative examples of clad materials used in metal molded products according to one embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, an embodiment will be described with reference to the drawings. As shown in FIG. 2, the metal molded product 10 has a bent portion 11. The metal molded product 10 is applied to articles having the bent portion 11, such as containers, lids, covers, and the like. More specific uses of the metal molded product 10 include containers, lids, covers, and the like for various components used in vehicles, such as oil pans and inverter device casings. The metal molded product 10 is formed of a clad material 12 in which two or more layers of different metals are laminated, as shown in FIG. 1. The metal molded product 10 has flat portions 13 in the area excluding the bent portion 11. The bent portion 11 is located between two flat portions 13.

[0011] The clad material 12 according to this embodiment includes a first layer 21 and a second layer 22. The first layer 21 is made of an Al-based material. Examples of the Al-based material include aluminum or an alloy primarily composed of aluminum. Specifically, Al-based materials include the A1000, A2000, A3000, A5000, and A6000 series alloys specified in JIS standards, with the A1000, A2000, and A5000 series alloys being preferred. In particular, the A2000 and A5000 series alloys are more preferred for strength. The second layer 22 is made of an Fe-based material. Examples of the Fe-based material include alloys primarily composed of iron, such as steel and stainless steel. Specifically, the Fe-based material is preferably hypoeutectoid steel or stainless steel. The first layer 21 and second layer 22 of the clad material 12 are bonded by diffusion bonding.

[0012] The first layer 21 is located on the inside of the bent portion 11 of the metal molded product 10. The first layer 21 has a surface 23 on the inside of the bent portion 11. The second layer 22 is located on the outside of the first layer 21 at the bent portion 11 of the metal molded product 10. An interface 24 is formed between the first layer 21 and the second layer 22. That is, the first layer 21 has a surface 23 exposed on the inside of the bent portion 11 and an interface 24 bonded to the second layer 22 on the side opposite the surface 23. When the first layer 21 is located on the inside of the bent portion 11, the angle D formed by the two flat portions 13 sandwiching the bent portion 11 is 60° to 150°. The angle D is preferably 80° to 100°.

[0013] The thickness of the flat portion 13 of the metal molded product 10 is preferably 2.0 mm or less. Meanwhile, the thickness of the bent portion 11 is 1.05 to 1.60 times that of the flat portion 13. This is because, when the flat clad material 12 is bent to form the bent portion 11 of the metal molded product 10, the Al-based material of the first layer 21 located in the bent portion 11 is compressed at the bent portion 11. The thickness of the first layer 21 is preferably 1.0 to 7.5 times that of the second layer 22. The thickness of the first layer 21 is more preferably 2.0 to 5.0 times that of the second layer 22. If the thickness of the first layer 21 is less than 1.0 times that of the second layer 22, the thickness of the first layer 21 relative to the total thickness of the metal molded product 10 becomes too small, thereby reducing the weight reduction effect. Furthermore, if the thickness of the first layer 21 is too small, deformation due to compression of the first layer 21 at the bent portion 11 is reduced, making it difficult to refine the crystal grains. Taking these into consideration, the thicknesses of the first layer 21 and the second layer 22 are adjusted according to the mass and strength required for the cladding material 12 .

[0014] The observation area 30 shown in FIG. 3 is arbitrarily set within the range indicated by the two-dot chain line in FIG. 1 on a cross section of the clad material 12 along the thickness direction in the bent portion 11. That is, the observation area 30 is set as an area arbitrarily extracted from the area surrounded by the two-dot chain line in FIG. 1. This observation area 30 includes the first layer 21, the second layer 22, the surface 23, and the interface 24 of the clad material 12 in the bent portion 11. The interface 24 appearing in this observation area 30 is referred to as interface line 31. That is, the interface 24 between the first layer 21 and the second layer 22 exists throughout the entire clad material 12 constituting the metal molded product 10. Similarly, the surface 23 appearing in the observation area 30 is referred to as surface line 32. That is, the surface 23 appearing in the observation area 30 of the entire surface 23 of the first layer 21 is referred to as surface line 32. As a result, the interface line 31 and the surface line 32 appear as curves in the observation area 30 corresponding to the shape of the bent portion 11 of the metal molded product 10.

[0015] In the observation region 30, a first region 41 is set with reference to the interface line 31, and a second region 42 is set with reference to the surface line 32. The first region 41 is a region set in the observation region 30 from the interface line 31 toward the surface 23 at a distance of 50 μm. In other words, when the first region lines 51 are set at intervals of 50 μm from the interface line 31 toward the surface 23, the first region 41 is set between the interface line 31 and the first region line 51. Similarly, the second region 42 is a region set in the observation region 30 from the surface line 32 toward the interface 24 at a distance of 100 μm. In other words, when the second region lines 52 are set at intervals of 100 μm from the surface line 32 toward the interface 24, the second region 42 is set between the surface line 32 and the second region line 52.

[0016] In the observation region 30, a first virtual line 61 and a second virtual line 62 are further set with the interface line 31 as a reference. The first virtual line 61 is a virtual line that is included inside the first range 41 and is equidistant from the interface line 31. That is, the first virtual line 61 is set to have the same curved shape as the interface line 31 inside the first range 41 that is 0 to 50 μm from the interface 24. The second virtual line 62 is a virtual line that is included inside the second range 42 and is equidistant from the interface line 31. That is, the second virtual line 62 is set to have the same curved shape as the interface line 31 inside the second range 42 that is 0 to 100 μm from the surface 23.

[0017] When the first virtual line 61 and the second virtual line 62 are set in the observation region 30 in this manner, the first virtual line 61 intersects with the grain boundaries on the interface 24 side of the Al-based material constituting the first layer 21. Similarly, the second virtual line 62 intersects with the grain boundaries on the surface 23 side of the Al-based material constituting the first layer 21. The number of grain boundaries in the first layer 21 through which the first virtual line 61 passes is defined as a first value X. Similarly, the number of grain boundaries in the first layer 21 through which the second virtual line 62 passes is defined as a second value Y. In this case, the relationship between the first value X and the second value Y is 1.1≦Y / X≦5.0. That is, in this embodiment, the second value Y, which is the number of grain boundaries intersecting with the second virtual line 62, is greater than the first value X, which is the number of grain boundaries intersecting with the first virtual line 61. More preferably, the relationship between the first value X and the second value Y is 1.5≦Y / X≦4.5. If the second value Y is greater than five times the first value X, the hardness of the surface 23 side of the first layer 21 becomes excessively high, making the first layer 21 more susceptible to cracking. Furthermore, if the relationship between the second value Y and the first value X is 1.0≦Y / X<1.1, the number of grain boundaries in the first layer 21 becomes uniform between the surface 23 side and the interface 24 side. Therefore, the strength of the clad material 12 forming the metal molded product 10 is not improved.

[0018] In this embodiment, the first layer 21 located inside the bent portion 11 has finer crystal grains on the surface 23 side than on the interface 24 side. Therefore, as described above, the second value Y is greater than the first value X. By thus refining the crystal grains on the surface 23 side of the first layer 21, the first layer 21, formed of an Al-based material, has improved strength on the surface 23 side compared to the interface 24 side. That is, the Vickers hardness HV of the first layer 21 is greater on the surface 23 side than on the interface 24 side. Specifically, the hardness H2 of the second region 42 of the first layer 21 is 1.1 to 2.0 times the hardness H1 of the first region 41. By setting the hardness H2 of the second region 42 to 2.0 times or less the hardness H1 of the first region 41, the hardness of the first layer 21 as a whole becomes appropriate, making it easier to process into the metal molded product 10. The hardness H2 of the second region 42 is more preferably 1.2 to 1.5 times the hardness H1 of the first region 41. The hardness of the first layer 21 varies approximately linearly from the interface 24 to the surface 23 .

[0019] The clad material 12 may include a third layer 73 as shown in Fig. 4. The third layer 73 is provided on the opposite side of the second layer 22 from the first layer 21. The third layer 73 is formed of an Al-based material, similar to the first layer 21. By providing the clad material 12 with the third layer 73 formed of an Al-based material in this manner, the Fe-based second layer 22 is not exposed to the outside of the metal molded product 10. This reduces corrosion and improves the durability of the metal molded product 10.

[0020] Next, a method for manufacturing the metal molded product 10 of this embodiment will be described. In the clad material 12 used in the metal formed product 10 of this embodiment, an Al-based first layer 21 and an Fe-based second layer 22 are joined in a pressure welding process. The pressure welding of the first layer 21 and the second layer 22 in the pressure welding process is performed by cold pressure welding in an environment at approximately room temperature. The pressure welding in the pressure welding process is performed with a reduction ratio set to 30 to 60%. The clad material 12 formed by pressure welding is annealed in an environment at 200 to 450°C in an annealing process. The annealing in this annealing process controls the crystal grain size of the Al-based material forming the first layer 21 of the clad material 12 to a predetermined range.

[0021] The clad material 12 that has undergone the annealing process is processed into a metal molded product 10 by press working in the forming process. The press working in this forming process forms a bent portion 11 in a portion of the metal molded product 10. By pressing the bent portion 11 in the forming process, the first layer 21 located inside the bent portion 11 in the clad material 12 deforms more than the second layer 22 located outside the bent portion 11 in the metal molded product 10. Furthermore, the first layer 21, which is made of an Al-based material, is thicker and softer than the second layer 22, which is made of an Fe-based material. Therefore, when forming the bent portion 11, the first layer 21 is compressed more than the second layer 22. As a result, the first layer 21 located inside the bent portion 11 is more deformed on the surface 23 side than on the interface 24 side, resulting in refinement of the crystal grains, which are the metal structure. As a result, the crystal grains in the second region 42 of the first layer 21 are refined more than those in the first region 41, resulting in increased hardness.

[0022] The structure and strength of the crystal grains in the first region 41 and the second region 42 of the first layer 21 are controlled by the annealing process of the clad material 12. That is, by appropriately setting the annealing conditions in the annealing process, the crystal grains in the first region 41 and the second region 42 of the first layer 21 are controlled. Then, by pressing the clad material 12 in the forming process, the crystal grains in the first layer 21 in the bent portion 11, particularly in the second region 42, are selectively refined. The refinement of the crystal grains in the second region 42 in this forming process is also controlled by the annealing conditions in the annealing process. Note that the annealing process may be performed not only before the forming process as described above, but also after the forming process. This allows for more detailed control of the refinement of the crystal grains in the second region 42.

[0023] Next, examples and comparative examples of the metal molded product 10 according to the above embodiment will be described. In Examples 1 to 5, the clad material 12 used in the metal molded product 10 had a thickness of 1.2 mm after pressure welding. Specifically, the thickness of the Al-based first layer 21 after pressure welding in Examples 1 to 5 was 0.9 mm, and the thickness of the Fe-based second layer 22 after pressure welding in Examples 1 to 5 was 0.3 mm. In Examples 1 to 5, the Al-based first layer 21 was formed from A1050, an A1000 series steel, and the Fe-based second layer 22 was formed from hypoeutectoid steel. The materials that would become the first layer 21 and the second layer 22 were pressure-welded at a reduction rate of approximately 50% in the pressure welding process, and then annealed at 300°C in the annealing process to form the clad material 12. In Examples 1 to 5, the mass per unit area W was 4.77 kg / m 2 It was.

[0024] Comparative Example 1 is a clad material 12 in which the first layer 21 is 0.9 mm thick and the second layer 22 is 0.3 mm thick after pressure welding, similar to Examples 1 to 5 described above. However, in Comparative Example 1, the crystal grains and hardness of the first layer 21 are not controlled. That is, in Comparative Example 1, the first layer 21 has roughly uniform crystal grains from the interface 24 side to the surface 23 side due to excessive annealing in the annealing process. Therefore, in Comparative Example 1, the ratio Y / X of the first value X to the second value Y is 1.00, and the hardness H1 of the first region 41 and the hardness H2 of the second region 42 are the same. The mass W per unit area of ​​Comparative Example 1 is 4.77 kg / m, the same as in Examples 1 to 5. 2 It was.

[0025] Comparative Examples 2 to 4 are all samples made of a single material using Al-based A1000 series A1050, and the thicknesses are varied. Comparative Example 2 had a thickness of 3.0 mm. The mass W per unit area of ​​Comparative Example 2 was 8.04 kg / m 2 In Comparative Example 3, the thickness was set to 2.0 mm. The mass W per unit area of ​​Comparative Example 3 was 5.36 kg / m 2 In Comparative Example 4, the thickness was set to 1.2 mm. The mass W per unit area of ​​Comparative Example 4 was 3.22 kg / m 2 is.

[0026] Comparative Examples 5 and 6 are all samples made of a single material using Fe-based hypoeutectoid steel, and the thicknesses of the samples are varied. The thickness of Comparative Example 5 was set to 1.2 mm. The mass W per unit area of ​​Comparative Example 5 was 9.42 kg / m 2 In Comparative Example 6, the thickness was set to 0.6 mm. The mass W per unit area of ​​Comparative Example 6 was 4.71 kg / m 2 is.

[0027] (Strength test) Strength tests were conducted on each sample of Examples 1 to 5 and Comparative Examples 1 to 6. In Examples 1 to 5 and Comparative Examples 1 to 6, the clad material 12 was cut into a plate shape of 30 mm width x 30 mm length, and then bent by 90° at the center in the width direction by press working as shown in Fig. 5 to prepare a test piece 80. That is, the angle D at the bent portion 11 of the test piece 80 was 90°.

[0028] The test piece 80 was pressed from above using a jig 81 with the bent portion 11 facing upward. The testing machine used was an autograph (precision universal testing machine autograph: AG-IS). The strength test was verified using the maximum test force M when the test piece 80 was pressed using the jig 81 of the testing machine. A maximum test force of 0.50 N or more was evaluated as passing (◯), and a maximum test force of less than 0.50 N was evaluated as failing (×).

[0029] (Mass verification) The mass of the clad material 12 used to make the metal molded product 10 is preferably light, provided that the same strength is ensured. The conventional example used for comparison is the metal molded product 10 formed of a single Fe-based material with a thickness of 1.20 mm, which is used in Comparative Example 5. With Comparative Example 5 as the reference, those with a mass W per unit area less than 0.7 times the reference value were rated as "great effect: ○". On the other hand, those with a mass W per unit area of ​​0.7 times or more but less than 1.0 times the reference value were rated as "small effect: △", and those with a mass W per unit area of ​​1.0 times or more the reference value were rated as "no effect: ×".

[0030] (Verification of the number of grain boundaries) The number of grain boundaries in the clad material 12, which was the material for the metal molded product 10, was calculated for each sample in Examples 1 to 5 and Comparative Example 1. In Examples 1 to 5 and Comparative Example 1, the clad material 12 was cut into a plate measuring 8 mm wide and 15 mm long, and the surface in the thickness direction was mirror-finished to prepare a test specimen. These test specimens were immersed in a sodium hydroxide aqueous solution for 7 to 30 seconds, and then color-etched by immersing them in a potassium permanganate aqueous solution for 7 seconds. The first value X and the second value Y of the test specimens were visually counted from cross-sectional structure images taken at 500x magnification using an optical microscope (KEYENCE optical microscope: VHX-7100). Y / X was calculated based on the counted first value X and second value Y.

[0031] (Hardness verification) The hardnesses H1 and H2 of the first layer 21 of the clad material 12, which is the material for the metal molded product 10, were measured for each sample in Examples 1 to 5 and Comparative Example 1. In Examples 1 to 5 and Comparative Example 1, the clad material 12 was cut into a piece 8 mm wide and 15 mm long, and the surface in the thickness direction was mirror-finished to prepare a test specimen. The Vickers hardness of the test specimen was measured using a micro Vickers hardness tester (MITUTOYO: HM-200) when a load of 0.01 N was applied to the first region 41 and the second region 42. The hardness H1 of the first region 41 and the hardness H2 of the second region 42 were measured, respectively. H2 / H1 was calculated based on the measured hardnesses H1 and H2.

[0032] (Discussion of Examples and Comparative Examples) As shown in Figure 6, Examples 1 to 5, in which Y / X, which is based on the first value X and the second value Y, representing the number of grain boundaries, is controlled, show improved strength compared to Comparative Example 1, in which Y / X is not controlled even though the material is the same. Examples 1 to 5 demonstrate that high strength can be achieved even with a thickness that is half or less compared to Comparative Example 2, in which the metal molded article 10 is formed from a single Al-based material. Furthermore, Examples 1 to 5 also have a smaller mass W per unit area than Comparative Example 2, demonstrating that weight reduction can be achieved while maintaining strength. Comparative Examples 3 and 4 demonstrate that when the metal molded article 10 is formed from a single Al-based material, the strength is insufficient when the mass W per unit area is the same as that of Examples 1 to 5.

[0033] Comparative Example 5, in which the metal molded article 10 was formed using a single Fe-based material, showed that although the strength was sufficient, it was difficult to reduce the weight when the thickness was set to the same as in Examples 1 to 5. Similarly, Comparative Example 6, in which the metal molded article 10 was formed using a single Fe-based material, showed that the strength was insufficient when the mass W per unit area was set to the same as in Examples 1 to 5.

[0034] As described above, in the metal formed product 10 of this embodiment, the number of crystal grains in the first layer 21 located inside the bent portion 11 in the clad material 12 differs between the surface 23 side and the interface 24 side close to the second layer 22. Specifically, the Y / X ratio, hardness H1, and hardness H2 based on the number of grain boundaries in the first layer 21 are controlled in the bent portion 11. As a result, the crystal grains in the first layer 21 are finer on the surface 23 side of the bent portion 11 than on the interface 24 side. Therefore, the hardness of the first layer 21 is higher on the surface 23 side of the bent portion 11 than on the interface 24 side. As a result, the strength of the bent portion 11 and the overall strength of the clad material 12 are improved. Therefore, even when further weight reduction is desired, the strength can be increased without increasing the thickness of the clad material 12.

[0035] When the metal molded product 10 of this embodiment is used, for example, as a casing for a vehicle inverter, it is preferable to join the casing to other components using, for example, bolts or rivets without applying heat. This is because the clad material 12 of the metal molded product 10 is annealed to refine the first layer 21 in the bent portion 11 and control the Y / X ratio, hardness H1, and hardness H2 based on the number of grain boundaries. In other words, if heat exceeding the temperature in the annealing process is applied when joining to other components, such as by welding, the metal structure in the bent portion 11 will change, causing the crystal grains to coarsen and resulting in a change in hardness.

[0036] The present invention described above is not limited to the above-described embodiment, and can be applied to various embodiments without departing from the gist of the invention. [Explanation of symbols]

[0037] In the drawings, 10 denotes a metal molded product, 11 denotes a bent portion, 12 denotes a clad material, 21 denotes a first layer, 22 denotes a second layer, 23 denotes a surface, 24 denotes an interface, 30 denotes an observation area, 31 denotes an interface line, 32 denotes a surface line, 41 denotes a first area, 42 denotes a second area, 61 denotes a first virtual line, 62 denotes a second virtual line, and 73 denotes a third layer.

Claims

1. A metal molded product formed of a clad material and having a bent portion, The cladding material is a first layer formed of an Al-based material and having a surface located inside the bent portion; a second layer formed of an Fe-based material, laminated on the outside of the first layer at the bent portion, and forming an interface at the boundary with the first layer; In an observation area arbitrarily set on a cross section along the thickness direction of the clad material at the bent portion, The interface appearing in the observation area is defined as an interface line, and the surface appearing in the observation area is defined as a surface line; a first virtual line that is included in a first range set to a distance of up to 50 μm from the interface line toward the surface in the first layer and is equidistant from the interface line; When a line in the first layer that is included in a second range set to a distance of up to 100 μm from the surface line toward the interface and that is equidistant from the interface line is defined as a second virtual line, A first value X, which is the number of grain boundaries in the first layer that are intersected by the first virtual line in the first range, and a second value Y, which is the number of grain boundaries in the first layer that are intersected by the second virtual line in the second range, are separated by the following relationship: 1.1≦Y / X≦5.0 holds true, Metal molded products.

2. The hardness H2 in the second range is 1.1 to 2.0 times the hardness H1 in the first range. The metal molded product according to claim 1.

3. Further comprising a third layer provided on the opposite side of the first layer with the second layer interposed therebetween. The metal molded product according to claim 1.

4. The second layer is a hypo-eutectoid steel. The metal molded product according to claim 1.

5. the second layer is stainless steel; The metal molded product according to claim 1.

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