JP2819370B2 - Manufacturing method of corrosion resistant clad pipe - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a seamless clad pipe having excellent corrosion resistance, which is useful as a piping material for seawater desalination equipment and the like.

[0002]

2. Description of the Related Art Cu-Ni alloys are known as alloys having corrosion resistance to seawater. In particular, 90% Cu
It is also known that an alloy having a composition in which 1 to 3.5% Fe is added to -10% Ni has excellent seawater resistance, and the seawater resistance is greatly affected by the Fe content. ing. FIG. 2 shows the effect of the Fe content on the seawater resistance of a 90% Cu-10% Ni alloy. The seawater resistance is high in the range of about 1 to 3.5% of Fe content, and the maximum corrosion resistance is exhibited at about 2%. This Cu-N
A clad pipe having a lining layer made of an i-based alloy on the inner surface of the pipe is useful as a pipe constituent material of a seawater desalination apparatus. As a method of manufacturing a clad pipe, a welding pipe manufacturing method and a seamless pipe manufacturing method are industrially implemented. In a clad pipe made by a welding pipe method, a plate serving as an outer layer of the clad pipe and a plate serving as an inner layer thereof are pressed into contact with a plate mill to form a laminated plate, and this is pressed bend mill or UOE pipe mill. And formed into a cylindrical shape, and then the joint is welded. In the seamless pipe manufacturing method, two seamless pipes of different diameters prepared by casting or piercing and rolling are used as raw pipes, and they are fitted together, and then used for plug mill, mandrel mill, or punching press. Through the process of attaching and joining the fitting interfaces, the desired clad pipe is obtained.

[0003]

According to the welding pipe making method,
Although it is possible to manufacture a clad pipe having a large diameter (pipe diameter of about 400 mm or more), the resulting pipe body involves problems such as a decrease in corrosion resistance at a joint (welding heat affected zone) due to welding.
In addition, a post-heat treatment is required for refining the welded joint, and the larger the diameter, the more difficult the processing operation and the more complicated the process. The seamless pipe manufacturing method does not have disadvantages as in the above-mentioned welding pipe manufacturing method, but the processing process is limited to a pipe diameter of about 400 mm, which is necessary for a piping configuration of a seawater desalination apparatus or the like. It is impossible to produce a clad pipe having a large diameter. Therefore, the present invention relates to a clad pipe useful for a pipe configuration of a seawater desalination apparatus or the like, wherein the Cu-Ni-based alloy is used as a lining layer on the inner surface of the pipe,
There is no welded seam and there is no restriction on pipe size as in the conventional seamless pipe manufacturing method.
Over a large diameter pipe size exceeding 400 mm,
It is an object of the present invention to provide a method of industrial production without using special equipment and special operations.

[0004]

SUMMARY OF THE INVENTION The present invention relates to a method of manufacturing a corrosion-resistant clad pipe having an outer layer made of steel and an inner layer made of a Cu-Ni-Fe-based alloy. A capsule cylinder having a small pipe diameter is installed upright concentrically, and a gap between the outer cylinder and the capsule cylinder is charged with a powder or plate material of a Cu-Ni-based alloy as an inner layer forming material and then degassed and sealed. After the inner layer forming material is heated and melted, and the molten metal is adjusted to a Cu-Ni-Fe-based alloy composition containing predetermined Fe by diffusing and mixing Fe into the molten metal from the outer cylindrical body generated in the heating and melting process. It is characterized in that the molten metal is cooled and solidified, and then the capsule cylinder is removed.

[0005]

The Cu-Ni alloy loaded as the inner layer forming material on the inner surface of the outer cylindrical body is heated and melted through the solid-liquid interface between the molten metal and the outer cylindrical body. Cu-Ni-Fe containing a predetermined amount of Fe is diffused and penetrated into the molten metal by the Fe component of the cylindrical body.
Changes to the base alloy composition. The amount of Fe that diffuses into and enters the molten metal from the outer layer cylindrical body can be appropriately controlled by the heating and melting treatment temperature and the treatment time (holding time) as described later. Therefore, as a Cu—Ni-based alloy that is the inner layer forming material, Cu—N having a quantitative ratio of Cu and Ni adjusted according to the composition of the target inner layer metal of the clad pipe.
When the i-type alloy is loaded on the inner surface of the outer layer cylindrical body, the inner layer made of the Cu-Ni-Fe-based alloy containing the desired amount of Fe is controlled by controlling the amount of diffusion of Fe in the heating and melting step. Is obtained. Normally, when forming a laminated structure of different materials, if one of the constituent elements diffuses into the other, it will contaminate the material,
It can cause undesired changes in material properties,
Although care has been taken to avoid this, the present invention, contrary to this convention, uses the phenomenon of element diffusion at the contact interface of different materials to form the inner layer metal of the clad pipe.

In the present invention, the inner layer forming material (Cu-Ni alloy) loaded on the inner surface of the outer layer cylindrical body is heated and melted to form a two-layer laminated structure.
Depending on the size of the outer layer cylinder and the capsule cylinder, a seamless clad pipe having an arbitrary pipe diameter, wall thickness, and pipe length is manufactured, and there is no essential limitation on the design of the pipe size, and a large diameter exceeding 400 mm in pipe diameter. Manufacture of tubes is also easy. Furthermore, in the above-mentioned heating and melting process, metallurgical bonding is generated at the interface between the molten metal and the outer cylinder by a diffusion reaction between the solid phase and the liquid phase, so that the bonding strength of the lamination interface of the obtained clad pipe is secured. You.

Hereinafter, the present invention will be described in detail with reference to the drawings. In FIG. 3, reference numeral 10 denotes a steel cylinder (outer cylinder) of carbon steel or the like to be an outer layer of the clad pipe;
Is a capsule cylinder inserted into the hollow hole of the outer cylinder 10. The capsule cylinder 30 has two layers, a refractory material layer 31 and a metal tube 32, to prevent fusion of the molten metal in the heating and melting step. The outer layer cylindrical body 10 and the capsule cylindrical body 30 are installed upright concentrically on a doughnut-shaped base A1, and are hermetically joined to the base A by weldings W1 and W2, respectively. A Cu—Ni alloy is loaded between the outer cylindrical body 10 and the capsule cylindrical body 30 as an inner layer forming material. The inner layer forming material 20 is formed by molding a plate of a Cu-Ni-based alloy into a cylindrical shape, powder, or the like. When the gap width of the space to be loaded is small, or compared to the gap width, If the height of the cylinder is large, the use of a plate is advantageous for the loading operation.
After the inner layer forming material 20 is loaded into the gap between the outer cylindrical body 10 and the capsule cylindrical body 30, a donut-shaped lid plate B
And outer and inner circumferences thereof are hermetically joined by weldings W3 and W4. Further, the interior space in which the inner layer forming material 20 is loaded is evacuated through a degassing tube D formed in the lid B, and then the degassing tube D is press-sealed, followed by subjecting the capsule body 40 to a heat melting process. . The vacuum sealing of the inner space is performed by oxidizing the inner peripheral surface of the outer layer cylindrical body 10 and the inner layer forming material 20 during the heating and melting process (the oxidation inhibits the diffusion reaction at the layer interface, the inner layer quality and the bonding strength at the laminating interface). Vacuum degassing is about 1 × 1
The pressure may be set to 0 ^-4 Torr or less.

As shown in FIG. 4, for example, as shown in FIG. 4, the inner layer forming material 20 of the capsule body 40 is heated and melted in a bell type heating furnace F by setting the atmosphere in the furnace to a predetermined temperature. It can be performed by heating (conductive heat transfer) from the surface and the inner surface of the capsule cylinder 30. The heat-melting treatment is carried out at a temperature of about 30 to 50 from the melting point of the inner layer metal in order to secure the diffusion reaction at the interface between the melt of the inner layer forming alloy and the outer layer cylinder and to ensure the dense homogeneity of the inner layer metal.
It is preferably carried out at a temperature higher by ° C. The heat-melting treatment is accomplished in approximately 5 to 10 hours. After heating and melting,
The molten metal is cooled and solidified, and then the base A, the cover material B and the capsule cylinder 30 are removed, and a suitable machining is performed,
As shown in FIG. 5, a two-layer laminated seamless clad pipe comprising an outer layer 1 (steel cylinder) and an inner layer 2 (cooled and solidified layer of molten metal) is obtained.

The outer cylindrical body 10 of carbon steel or the like according to the present invention.
For the material, a material type according to the intended use of the clad pipe is appropriately selected. Further, Cu—N which is the inner layer forming material 20 is used.
The i-based alloy may contain a small amount of Fe (the amount of Fe after the heat-melting treatment for diffusing and infiltrating Fe does not exceed the upper limit of Fe).

[0010] The inner layer of the clad pipe manufactured according to the present invention has a Cu content of 85.5 to 90%,
It is preferable to adjust the composition to 9 to 11% Ni and 1 to 3.5% Fe. According to the present invention, the metal composition of the inner layer is given by the amount ratio of Cu and Ni in the Cu-Ni-based alloy used as the inner layer forming material 20 and the amount of diffusion and intrusion of Fe in the heat melting treatment. The diffusion penetration amount can be arbitrarily controlled by the heating and melting treatment temperature and the treatment time.
FIG. 1 shows 90% Cu-10% as the inner layer forming material 20.
In the case where the Ni alloy is loaded on the inner side surface of the outer layer cylindrical body 10 (carbon steel) and subjected to the heating and melting treatment, the time of the heating and melting treatment and the time of the formation of the inner layer alloy (Cu-Ni-Fe alloy) are determined. The relationship with the Fe content is shown. However, the heating and melting temperature is 1200 ° C., and the thickness of the inner layer is 5 m.
m. Further, the diffusion and intrusion of Fe from the capsule cylinder 30 are blocked (the test conditions are the same as in Examples described later). As shown in the figure, it can be seen that the amount of increase in Fe of the inner layer metal into which Fe diffuses from the outer layer cylindrical body 10 during the heating and melting process of the inner layer forming material can be accurately and accurately controlled by the heating and melting conditions.

In FIG. 1, the capsule cylinder 30
Although an example using a material having a refractory material layer 31 on the inner surface is shown as the example, this is not necessarily the case, and a steel cylinder such as carbon steel similar to the outer cylinder 10 may be used. In the heating and melting process in that case, it is also possible to shorten the heating and melting process time by diffusing and injecting Fe from the capsule cylinder 30. On the contrary, the ceramics (for example, the surface in contact with the inner layer metal)
Suitable layer thickness (for example, 30 to 10) made of zirconia) or the like.
If the coating layer of 0 .mu.m) is formed by a thermal spraying method or the like, the fusion of the inner layer metal with the molten metal in the heating and melting process is prevented, and therefore, the capsule cylinder 30
Of the capsule cylinder 30 can be easily used, and the capsule cylinder 30 can be repeatedly used as a jig.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS As shown in FIG.
And capsule cylinder 30 (refractory material 31 and steel cylinder 32)
, The inner layer forming material 20 is loaded and degassed and sealed (1 ×
1 ^-4) and Ue, charged into the bell-type furnace F (Figure 4), through heating and melting treatment of the inner layer forming an alloy to obtain a clad pipe a~d a two-layer structure shown in FIG. 5 [pipe size (Machine Processing) Outer diameter: 1610 mm, outer layer thickness: 20 mm, inner layer thickness: 5
mm]. Outer steel cylinder: SC46 carbon steel (centrifugally cast tube), melting point 1500 ° C. Inner layer forming alloy: 90% Cu-10% Ni alloy. Melting point about 1160 ° C. Heat melting treatment: Heating temperature 1200 ° C Processing time 2 to 15Hr

The chemical composition of each inner layer of the obtained test tubes a to d was analyzed, and the results shown in Table 1 were obtained. It can be seen that under the condition where the treatment temperature is constant, the heat melting treatment time is lengthened and the Fe content of the formed inner layer metal is increased, and the alloy composition of the inner layer metal can be controlled accurately by the treatment time. Further, the Cu—Ni—Fe alloy suitable for securing seawater resistance is formed by the heat melting treatment for about 5 to 10 hours. Further, in each of the test tubes a to d, the layer interface between the outer layer 1 and the inner layer 2 is metallurgically bonded over the entire circumference and the entire length, and the inner layer has a dense and homogeneous structure free of bubbles and the like. (By ultrasonic flaw detection inspection and cross-section macro etching inspection).

[0014]

[Table 1] Test material treatment time, inner layer metal composition, Wt% No. (Hr) CuNiFea 2 89.5 9.9 0.60 b 5 89.2 9.7 1.10 c 10 88.6 9.1 2.30 d 15 88.3 8.7 3.00

[0015]

According to the present invention, a simple treatment operation of heating and melting a Cu-Ni-based alloy loaded as an inner layer forming material on the inner surface side of a cylindrical body serving as an outer layer can provide a C-water having excellent seawater resistance.
A seamless clad pipe having a u-Ni-Fe-based alloy layer on the inner surface can be manufactured. In addition, there is no essential limitation on the pipe size that can be manufactured, and a large diameter (for example, a pipe diameter of 400 mm or more) that is difficult to manufacture by the conventional seamless pipe manufacturing method.
Is also easy to manufacture. The method of the present invention can be applied not only to large-diameter pipes, but also to the production of seamless clad pipes of various sizes required for piping construction, and its use is not limited to seawater desalination equipment, Needless to say, it is useful as piping and other piping materials.

[Brief description of the drawings]

FIG. 1 is a graph showing the relationship between the heat-melting treatment time of an inner layer forming material and the amount of Fe diffusion and intrusion.

FIG. 2 is a graph showing the relationship between the Fe content of a Cu—Ni—Fe alloy and corrosion resistance.

FIG. 3 is an explanatory sectional view of the method of the present invention.

FIG. 4 is an explanatory sectional view of the method of the present invention.

FIG. 5 is an explanatory sectional view of a clad pipe.

[Explanation of symbols]

1: outer layer, 2: inner layer, 10: outer layer cylinder, 20: inner layer forming material, 30: capsule cylinder.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification code FI B22D 23/00 B22D 23/00 Z B32B 15/01 B32B 15/01 Z // B23K 20/00 310 B23K 20/00 310E C23C 26 / 00 C23C 26/00 Z (58) Fields investigated (Int. Cl. ⁶ , DB name) B22D 21/00 B22D 19/00 B22D 23/00

Claims (2)

(57) [Claims] 1. A method for manufacturing a corrosion-resistant clad pipe having an outer layer made of steel and an inner layer made of a Cu—Ni—Fe alloy, comprising: a steel cylinder serving as an outer layer; and a capsule cylinder having a smaller pipe diameter. Are installed upright concentrically, and Cu-N is used as an inner layer forming material in a gap between the outer layer cylindrical body and the capsule cylindrical body.
After loading i-type alloy powder or plate material and degassing and sealing,
After the inner layer forming material is heated and melted, and the molten metal is adjusted to a Cu-Ni-Fe alloy composition containing a predetermined amount of Fe by diffusing and mixing Fe from the outer layer cylinder into the molten metal generated in the heat melting process. A method for producing a corrosion-resistant clad pipe, wherein the molten metal is cooled and solidified, and then the capsule cylinder is removed. 2. The addition of Fe allows Cu: 8.
5.5 to 90%, Ni: 9 to 11%, Fe: 1 to 3.5
% Of Cu and Ni in an amount ratio to become a Cu—Ni-based alloy
Is used as the inner layer forming material, and by diffusion and mixing of Fe from the outer layer cylindrical body generated in the heating and melting process,
The method for producing a corrosion-resistant clad pipe according to claim 1, wherein the molten metal is adjusted to the above composition.