JP4264520B2 - Clad material and manufacturing method thereof - Google Patents

Description

  The present invention relates to a clad material having an aluminum / cadmium / aluminum structure formed by coating the entire outer peripheral surface of a toxic cadmium (sometimes referred to as Cd) material with an aluminum (sometimes referred to as Al) material. It relates to a manufacturing method.

  In neutron scattering experimental facilities, Gd is generally used as a neutron poison material, but recently, cadmium, cadmium-rich AgCdIn alloy, B4C, and the like are also being studied. Among them, cadmium is more effective as a neutron poison material because neutron absorption efficiency is better than Gd. Since neutron poison is used in liquid hydrogen, it is coated with aluminum, which has a proven track record of coexistence with liquid hydrogen, but this coating is thermally removed to remove the heat of nuclear reaction associated with neutron absorption by cadmium. It must be well bonded to cadmium so as not to create resistance.

  As a method for producing this aluminum / cadmium / aluminum-structured clad material, there is a method in which cadmium is sandwiched between aluminum materials in a sandwich shape and produced by the HIP method (Hot Isostatic Pressing). Other methods such as the cold spray method and the cadmium-aluminum plate deposition method have been studied, but these have not yet been put into practical use.

However, according to the HIP method, since the processing temperature is as high as 500 ° C., there is a problem that cadmium having a melting point of 321 ° C. is melted.
Furthermore, Al6061 (unit: wt%, Si: 0.4 to 0.8, Fe: 0.7 or less, Cu: 0.15 to 0.4, Mn : 0.15 or less, Mg: 0.8 to 1.2, Cr: 0.04 to 0.35, Zn: 0.25 or less, Ti: 0.15 or less, the balance: substantially Al) In such a case, the mechanical properties are lost by the HIP treatment at the above temperature, and therefore it is necessary to re-treat the aging treatment.

The problems to be solved are as follows. That is,
(1) Cadmium material melts in the production of clad material
(2) If the aluminum material is an alloy that has been aged, the mechanical properties will be lost (so it will be necessary to re-age)
(3) Since cadmium is toxic, it needs to be treated to prevent contamination with cadmium during normal processing, but it is difficult to handle with ordinary equipment and requires extensive pollution control equipment.
(4) Both the aluminum material and cadmium material that make up the cladding material require large-scale anti-oxidation equipment to prevent oxidation under high temperature heating conditions in an oxidizing atmosphere.
(5) Since there is a large difference in deformation resistance between the aluminum material and the cadmium material that make up the clad base material, so-called one-component deformation, in which only the aluminum material is deformed during rolling, is likely to occur and sufficient rolling force can be applied. Therefore, the bonding becomes insufficient, and it is difficult to control the thickness ratio, and it is difficult to produce the desired clad material unless the optimum conditions are selected during the rolling process.

  The present invention has been made to solve the above-mentioned many problems. First, a cadmium material is a clad material whose entire outer peripheral surface is clad inside an aluminum material, and secondly, The clad material according to the first aspect, wherein the cadmium material is disposed at a substantially central portion inside the aluminum material. Third, one or both of two aluminum materials having substantially the same shape surface A cadmium material is disposed in a recess formed in the surface of the aluminum material, both surfaces of the aluminum material are brought into contact with each other, and the outer peripheral edge of the contact surface is joined to produce a clad base material, and then the base material A method for producing a clad material in which the entire outer peripheral surface of a cadmium material is clad with an aluminum material, and fourthly, the joining of the outer peripheral edge is performed by electron beam welding in vacuum A method for producing a clad material according to the third aspect, and fifth, a method for producing a clad material according to the third or fourth method, wherein the first pass of the rolling is hot rolling at 180 ° C. or higher, Sixth is the method for producing a clad material according to the third or fourth aspect, wherein the rolling is cold rolling performed a plurality of times with a single rolling reduction rate of less than 10%, and seventh, the rolling is a total rolling reduction rate. It is a manufacturing method of the clad material according to any one of Nos. 3 to 6, which is a rolling of 40 to 90%. Finally, according to the manufacturing method according to any of Nos. 3 to 7, all of the cadmium material is A clad material characterized in that an outer peripheral surface is clad with an aluminum material.

  According to the present invention, the entire outer peripheral surface of the cadmium material is covered with the aluminum material, and then the rolling process is performed at a temperature lower than the melting point of cadmium. (1) The cadmium material may be melted in the production of the clad material. (2) Even if the aluminum material is an aging-treated alloy, its mechanical properties are not lost. (3) (4) Large contamination prevention equipment and large oxidation prevention equipment in manufacturing Can be manufactured at low cost with simple manufacturing equipment, (5) can be manufactured efficiently under optimal conditions, and (6) aluminum material in the resulting cladding material And a cadmium material can provide a clad material that can maintain a high reliability with a sound bond at the interface between the cadmium material and the cadmium material.

  As the aluminum material in the present invention, not only pure aluminum but also an aluminum-based alloy such as Al 6061 described above can be used. When an aluminum-based alloy is used, the mechanical properties are not lost in the clad manufacturing process even when the aging-treated one is used in the present invention. Moreover, as two aluminum materials used for clad manufacturing, not only pure aluminum, but also aluminum based alloys of the same composition, for example, a combination of pure aluminum and an aluminum based alloy, or a combination of different aluminum based alloys Thus, different types of aluminum materials can be used. On the other hand, as the cadmium material, either pure cadmium or a cadmium-based alloy can be used. It needs to be rolled.

  The manufacturing process of the clad material will be described in more detail based on the conceptual diagram of FIG. That is, for example, a container 1 in which a recess (recess) of 110 mmW × 56 mmL × 3.5 mmt is formed in a substantially central portion of the surface of an aluminum plate of 130 mmW × 200 mmL × 6 mmt by cutting or the like (a recess for placing a cadmium material is provided. An aluminum material formed on the surface to be clad), a lid 2 (another aluminum material) of an aluminum plate of 130 mmW × 200 mmL × 2.5 mmt, and cadmium fitted into the recess with substantially the same dimensions as the recess. A plate 3 (cadmium material disposed in the concave portion of the aluminum material) is prepared.

After both surfaces of the aluminum container 1 and the lid 2 are in contact with each other, inside the recess of the aluminum container 1 and the cadmium plate 3 are polished to remove the oxide film on the surface, these are combined and vacuumed as described above (FIG. 1). The clad base material 4 is obtained by joining the seam (outer peripheral edge portion of the contact surface) of the aluminum container 1 and the lid 2 set in the chamber and brought into contact with each other by electron beam welding.
The joined clad base material 4 (vessel with a lid) is directly subjected to cold rolling a plurality of times at a constant reduction rate in the air atmosphere, or heated to a predetermined temperature with a heat treatment facility in the air atmosphere and then the air atmosphere. Among them, the rolling is performed to a predetermined total rolling reduction by performing hot rolling one or more times.

At this time, in the case of performing cold rolling, cracks are generated in a welded portion or the like when the reduction rate of one time is set to 10% or more.
On the other hand, in the case of performing hot rolling, the rolling reduction per one time can be 10% or more. However, when the temperature of the first pass of the material (clad base material 4) is less than 180 ° C., deformation resistance of aluminum and cadmium is reduced. 1 component deformation occurs, cracks occur at the boundary between aluminum and cadmium, and aluminum deforms greatly in the width direction, making it difficult to produce the desired cladding material. The eyes are hot-rolled at a temperature of 180 ° C. or higher.

  In the first pass, when hot rolling is performed at 180 ° C. or higher to form a healthy clad interface, and then tandem (continuous) hot rolling is performed, the second pass and subsequent passes are 180 ° C. Even if it is less than, there is no problem. Furthermore, the upper limit of the material temperature during hot rolling can theoretically be raised to a temperature lower than the melting point of the cadmium material or lower than the liquid phase generation temperature. Cadmium melting point (321 ° C.) or liquid phase generation temperature may occur and cadmium material may be melted, making it difficult to manufacture the clad material. .

  The above describes the case where the cadmium material is disposed by forming a recess on the surface of one of the two aluminum materials, but the recesses are formed on the surfaces of both aluminum materials, The case where one cadmium material is arranged so as to fit together or one cadmium material is arranged so as to fit in both concave portions is the same as the above case.

  The present invention will be described in more detail with reference to the following examples. However, the technical scope of the present invention is not limited to the description of the following examples.

  FIG. 1 is a conceptual diagram of a clad base material 4 in which a cadmium plate 3 is fitted in an aluminum container 1, a lid 2 of the aluminum plate is brought into contact, and the outer peripheral edge of the contact surface is joined by electron beam welding in a vacuum. is there. Table 1 describes in detail the heating temperature, rolling reduction, cladding conditions, results, and the like during rolling of the examples of the present invention and comparative examples, and will be described below with reference to these. In the following description, both the aluminum materials were rolled on the above-mentioned Al 6061 aluminum base alloy, and the cadmium material was pure cadmium.

  [Embodiment 1] Embodiment 1 is a case where the clad base material 4 is heated to 210 ° C. and a rolling reduction of 50% is applied in one pass and hot rolling is performed in an air atmosphere by a rolling mill. The aluminum material was uniformly rolled in a joined and integrated state, and no crack was generated, and the cladding condition was good.

  [Comparative Example 1] Comparative Example 1 is a case where the clad base material 4 was rolled in the same manner as in Example 1 except that the clad base material 4 was heated to 150 ° C. The aluminum-only portion without cadmium was rolled to 4.25 mmt. However, the portion where cadmium is present can only be rolled to 6.6 mmt, and the value in the width direction of the portion where cadmium is present is 137 mmW wider than 130 mmW where the cadmium is not present. Furthermore, cracks occurred at the boundary between aluminum and cadmium.

  [Example 2] Example 2 is a case where hot rolling was performed in the same manner as in Example 1 except that the clad base material 4 was heated to 200 ° C each time and then the total reduction ratio was 77% in 5 passes. The two aluminum materials were uniformly rolled in a state where they were joined and integrated, and there was no generation of cracks, and the cladding condition was good.

  [Comparative Example 2 and Comparative Example 3] Comparative Example 2 and Comparative Example 3 were the same as those in Example 1 except that the cladding base material 4 was heated to 150 ° C. each time and 74% was performed in 5 passes and 44% in 4 passes. In the case of rolling in the same manner, cracks occurred at the boundary between aluminum and cadmium in the fourth pass and the third pass, respectively.

  [Example 3] Example 3 is a case where the clad base material 4 is first heated to 200 ° C and then continuously rolled in 5 passes at a total rolling reduction of 51%. The clad was in good condition with no cracks.

  [Example 4] Example 4 is a case where all the clad base materials 4 were subjected to 13 passes at a reduction ratio of less than 10% and cold-rolled at a total reduction ratio of 48%. The clad was in good condition with no cracks.

  [Comparative Example 4] In Comparative Example 4, when cold rolling was performed at a reduction rate of 12% in the second pass, cracks occurred in the electron beam weld.

  Cadmium material with good neutron absorption efficiency is coated with aluminum material that has a proven track record of coexistence with liquid hydrogen and is suitable for use as a neutron poison material essential for neutron scattering experimental equipment. Can be applied to.

A cladding base material 4 in which a cadmium plate 3 is fitted in an aluminum container 1 and a lid 2 of the aluminum plate is brought into contact with the outer peripheral edge of the contact surface joined by electron beam welding in a vacuum. It is the conceptual diagram which appeared through the cadmium board 3 which cannot be seen, Comprising: The front view, a side view, and a top view are shown.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Aluminum container 2 Aluminum lid 3 Cadmium plate (Transparent part. Actually it cannot be seen from the outside.)
4 Clad base material

Claims (8)

  A clad material in which the entire outer peripheral surface of a cadmium material is clad inside an aluminum material.   The clad material according to claim 1, wherein the cadmium material is disposed at a substantially central portion inside the aluminum material.   A cadmium material is disposed in a recess formed in one or both of the two aluminum materials having substantially the same shape, and the both surfaces of both aluminum materials are brought into contact with each other. A method for producing a clad material in which the entire outer peripheral surface of a cadmium material is clad with an aluminum material, wherein the outer periphery of the cadmium material is joined to produce a clad base material, and then the base material is rolled.   The method for manufacturing a clad material according to claim 3, wherein the joining of the outer peripheral edge is electron beam welding in a vacuum.   The method for producing a clad material according to claim 3 or 4, wherein the first pass of the rolling is hot rolling at 180 ° C or higher.   The method for producing a clad material according to claim 3 or 4, wherein the rolling is cold rolling performed at a plurality of times with a rolling reduction rate of less than 10%.   The method for producing a clad material according to any one of claims 3 to 6, wherein the rolling is rolling with a total rolling reduction of 40 to 90%.   A clad material, wherein the entire outer peripheral surface of a cadmium material is clad with an aluminum material by the manufacturing method according to claim 3.

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