JPH0362486B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to a method for producing a double-layer metal piece for hot extrusion pipe manufacturing, and more specifically to a method for producing a seamless double-layer pipe produced by hot extrusion pipe production, particularly for ultra-high temperature and high pressure use in thermal power generation. The present invention relates to a method for producing a two-layer metal piece for hot extrusion pipes, which is suitably used for producing clad pipes such as boiler tubes. [Prior Art] Conventionally, methods for producing long seamless double-walled pipes include a plug mill rolling method and an Atsel mill rolling method. In all of these methods, in order to bring the mating surfaces into close contact, the outer diameter of the inner layer material is made larger than the inner diameter of the outer layer material when assembling the materials, and the material is press-fitted. Both ends of this mating surface are welded and sealed in the atmosphere to prevent oxidation during heating and pipe manufacturing before hot pipe manufacturing, and air existing at the mating surface is removed or argon purge is performed. Processing is in progress. [Problems to be Solved by the Invention] However, since the pipe manufacturing methods using the plug mill rolling method and the Atsel mill rolling method have extremely harsh processing conditions, it is difficult to produce pipes when the thickness of one side of the laminated material is as thin as about 2 mm or less. However, it has been difficult to produce products with guaranteed quality, that is, products with uniform thickness (particularly of laminated materials) with little thickness deviation. Furthermore, in the plug mill rolling method and the Atsel mill rolling method, materials are press-fitted during assembly, but if one of the materials is thin, buckling may occur during press-fitting or scratches may be left on the mating surfaces. As a result, it was not possible to use very thin materials, and it was difficult to make a product in which one of the materials had a thickness of 2 mm or less. On the other hand, there are many demands from customers for clad pipes in which one material has a thickness of about 2 mm or less, for example about 1 mm, and a pipe manufacturing method that can meet this demand has been desired. Therefore, the main problem of the present invention is that even if the thickness of one of the materials is 2 mm or less,
The purpose is to produce layered metal pieces. [Means for Solving the Problems] In view of the problems of the above-mentioned prior art, the present inventors have
We investigated methods suitable for manufacturing long cladding pipes, especially cladding pipes in which one of the materials is particularly thin, and found that hot extrusion is (1) difficult to process because there is no spiral metal flow during pipemaking; (2) Therefore, the method of joining the materials does not need to be press-fitting; there may be a gap between the two materials; (3) Therefore, thin-walled materials should be used. It was concluded that this method is the most suitable as a method for manufacturing long cladding tubes in that it is possible to easily manufacture cladding tubes with very thin walls, for example, 2 mm or less. That is, in the present invention, metal materials for the outer layer and for the inner layer, which have mutually different chemical compositions and are formed into a substantially cylindrical shape, are each formed with a gap between the mating surfaces of the two metal materials. The extruded rear end surfaces of the two are fitted together to form a composite material, and in this state, the above-mentioned gap at the extruded tip of the composite material is sealed by welding in the atmosphere, and then the gap is placed in a vacuum state. Welding is performed by irradiating an electron beam in the radial direction of the laminated material from the outer surface of the metal material for the outer layer at a position substantially separated from the rear end surface at the extruded rear end of the laminated material, thereby forming a bead on the rear end surface. This is characterized in that the above-mentioned gap at the rear end of extrusion is sealed without forming it. [Operation] The basic idea of the present invention is as follows. (1) When assembling two-layer metal pieces or laminated materials, the two metal materials are fitted with a gap between them. This is to ensure ease of assembly work. This makes it possible to assemble even extremely thin metal materials. (2) Weld both ends of the mating material to seal between the two metal materials. As for the welding method, first, seal welding is performed on the tip of the composite material in the atmosphere with the extruded rear end surfaces of the composite materials aligned.
Next, (3) vacuum the gap between both metal materials. This is to prevent the formation of an oxide film on the mating surfaces during heating of the two-layer metal piece before hot extrusion and during pipe production, and to eliminate the cause of separation of the double-layered pipe during hot pipe production. Then, while keeping this gap in a vacuum, the rear end portion of the extrusion is sealed and welded using an electron beam. Electron beam welding is performed by irradiating an electron beam from the outer surface of the metal material for the outer layer in the radial direction of the composite material to form penetration in the radial direction so that no bead is formed on the extruded rear end surface. That is, the extruded rear end surfaces of the laminated materials are arranged to lie within the same plane, and no portion is formed that protrudes rearward from this plane. This is because during hot extrusion pipe making, the extruded end of the laminate comes into contact with the dummy block and receives pressure, so if the surfaces that come into contact with the dummy block are not on the same plane, each metal material of the laminate will be uneven. The welded part is damaged due to the metal flow phenomenon that is unique to hot extruded pipes.
This is to allow air to enter, which causes an oxide film to form on the mating surfaces, and to eliminate the cause of uneven thickness. (Example) Next, the present invention will be described in more detail based on an example shown in the drawings. FIG. 1 is a schematic diagram showing a method of manufacturing a two-layer metal piece for hot extrusion pipe production according to the present invention. Reference numeral 1 indicates a metal material for the outer layer of the two-layer metal piece, and 2 indicates a metal material for the inner layer. Both of the metal materials 1 and 2 are formed into a generally cylindrical shape. The metal materials 1 and 2 have mutually different chemical compositions, and each has properties required depending on the application. The example shown is an example of a two-layer metal piece used in the manufacture of boiler tubes for ultra-high temperature and high pressure.The inner layer metal material 2 made of TP310 is used as the base material, and the thin outdoor layer metal material made of SUS347H is used as the base material. 1 is coated. According to the above-mentioned basic structure of the method of the present invention, in this embodiment, the inner diameter of the metal material 1 for the outer layer is formed larger than the outer diameter of the metal material 2 for the inner layer. The difference between the inner diameter of the outer layer metal material 1 and the outer diameter of the inner layer metal material 2, that is, the gap 4 between the mating surfaces of the two metal materials 1 and 2 when they are assembled is:
It is sufficient that the two metal materials 1 and 2 can be easily fitted together. There is no need to make the gap 4 larger than that, and if the gap 4 is too large, it is very difficult to seal the two metal materials 1 and 2 by welding as described later.
Therefore, the gap 4 between the two metal materials 1 and 2 is usually
Approximately 0.1 to 1 mm is appropriate. Both metal materials 1, 2 have substantially the same length, and in the assembled state, the extrusion front end surfaces 1a, 2a and/or at least the extrusion rear end surfaces 1b, 2b are aligned in the same plane. It is a necessary condition that at least the extruded rear end surfaces 1b and 2b are aligned in the same plane, but this requires that a continuous plane be formed over the entire area of the extruded rear end of the laminated material 3. Instead, it is sufficient that the extruded rearmost end portions of each of the metal materials 1 and 2 are aligned in the same plane and can evenly contact the dummy block at that portion during hot extrusion pipe manufacturing in the subsequent process. . In the illustrated example, a thin wall portion 11 is formed in an annular shape at the extruded rear end of the outer layer metal material 1 along its circumferential surface. As will be described later, the thin wall portion 11 is irradiated with an electron beam in the radial direction from the outer surface of the outer layer metal material 1 to perform welding with the inner layer metal material 2. The thickness must be such that the electron beam can easily pass through it, and the metal material 1 for the outer layer must have a thickness that does not cause buckling during extrusion. In addition, with this shape, the welded part between the outer layer metal material 1 and the inner layer metal material 2 is smaller than the outer diameter of the outer layer metal material 1, so that no scratches will be created on the outer surface of the tube during hot extrusion tube manufacturing. There are advantages such as However, if the thickness of the metal material 1 for the outer layer is already sufficiently thin and it is not necessary or possible to provide the thin section 11 as described above, after welding the outer surface near the rear end, Take measures such as scraping off the built-up area. The width of the thin portion 1b, that is, the length in the axial direction of the outer layer metal material 1, is generally preferably about 5 to 10 mm. This is because when the outer layer metal material 1 is melted in the radial direction by electron beam irradiation to form a weld, the shape of the extruded rear end surfaces 1b and 2b of the metal material becomes irregular, or a bead is formed on the extruded rear end surface. This is to prevent the flatness of the extruded rear end surface from being damaged. Therefore, the electron beam irradiation is performed within the thin wall portion 11 at a position slightly moved forward from the extrusion rear end surface 1b. In addition, if the coefficients of thermal expansion of the two metal materials 1 and 2 to be assembled are significantly different, electron beam welding may be performed in the circumferential direction at the axially intermediate portion of the mating material other than the rear end of the extrusion. A method is used to restrain the displacement of both metal materials 1 and 2 when one side is heated. In this embodiment, grooves 12 and 21 for welding are formed at the extruded tip portions of both metal materials 1 and 2. In terms of workability, TIG arc welding or welding in the atmosphere using a hand rod is used to weld this part. When manufacturing a two-layer metal piece, first, the inner layer metal material 2 is inserted into the outer layer metal material 1 formed as described above with a gap 4, and the extruded rear end surfaces 1b and 2b are aligned. Laminating material 3 is assembled. Next, the extruded tip portions of this laminated material 3, specifically the beveled portions 12 and 21, are
TIG arc welding or hand stick welding 5 is performed in the atmosphere to seal the extruded tip portion of the gap 4 between the two metal materials 1 and 2. Next, the inside of the gap 4 is evacuated, and in this state, an electron beam is radially applied to the outer surface of the thin wall portion 11 to perform welding 6 in the radial direction, thereby sealing the extruded rear end of the gap 4. The degree of vacuum is preferably 10 ^-3 Torr or higher. In this way, a two-layer metal piece for hot extrusion making pipes with the extruded rear end surfaces on the same plane is formed.
Therefore, during hot extrusion pipe manufacturing, it is possible to omit the step of flattening the extrusion rear end surface. FIG. 2 shows an example of a specific method of performing electron beam welding while keeping the gap 4 between the two metal materials 1 and 2 in a vacuum state. chamber 7
After creating a vacuum, welding is performed using an electron beam. Inside the chamber 7, the extrusion material 3 is rotated about the axis A with its extruded tip portion held by the chuck 9. With respect to this laminated material 3, the thin part 1 of the metal material 1 for outer layer
A focused electron beam is irradiated to a predetermined position of the laminated material 3, and welding is performed on the entire circumference of the laminated material 3 from the radial direction. (Experiment example) Using the two-layer metal piece shown in Table 1, the outer diameter was 51.6 mm.
× Thickness 11.4mm (outer layer 1.5mm, inner layer 9.9mm) × length 7000
mm clad tube was manufactured.

〔Effect of the invention〕

As described above, the present invention can improve the adhesion of hot extruded double-pipe pipes, and can also easily and excellently produce double-layer metal pipes, especially when the metal material of the laminated material is thin. This has the effect of making it possible to manufacture pieces.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram showing the method of the present invention, and FIG. 2 is an explanatory diagram showing a specific example for vacuum sealing the rear end of the laminated material. 1... Metal material for outer layer, 2... Metal material for inner layer, 3
... Laminated material, 4... Gap, 5... Tip welding, 6... Rear end welding, 7... Vacuum champer, 8... Vacuum pump, 11... Thin wall part.

Claims (1)

[Claims] 1 have mutually different chemical compositions, and
The metal materials for the outer layer and the inner layer, which are formed into a substantially cylindrical shape, are fitted together with a gap between the mating surfaces of both metal materials so that their respective extruded rear end surfaces become flush. form,
In this state, the above-mentioned gap at the extruded tip of the laminated material is sealed by welding in the atmosphere, and then, while keeping the gap in a vacuum state, at a position substantially separated from the rear end surface at the extruded rear end of the laminated material. A hot welding method characterized by sealing the above-mentioned gap at the rear end of extrusion without forming a bead on the rear end surface by irradiating the outer surface of the metal material for the outer layer with an electron beam in the radial direction of the composite material and welding. A method for producing a two-layer metal piece for extruded pipe manufacturing.