JPH0755338B2 - Clad metal tube manufacturing method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention has a ratio of (combination material thickness / combination material outer diameter) of 0.02 or less on the inner surface or outer surface or both inner and outer surfaces of a base material, / Total cross-sectional area) ratio is 0.25 or less, specifically 0.3 to
The present invention relates to a method for manufacturing a clad metal tube in which a very thin mating material having a thickness of 0.05 mm is joined.

More specifically, it relates to a method for producing a clad metal tube made of a shape memory alloy or an intermetallic compound alloy having excellent corrosion resistance.

(Prior Art) Conventionally, a clad metal tube has been mainly subjected to hot rolling or hot extrusion for a clad tube with stainless steel or Ni-based alloy which is a composite material mainly for improving the corrosion resistance of carbon steel as a base material. It is manufactured by the processing method. It is also manufactured by the partial explosion method. JP-A-53-19958, JP-A-5
3-14155, JP-B-58-43237, JP-A-58-1
See 3404 publication. From the viewpoint of cost and productivity, the hot rolling method is superior, and it is usually manufactured by a conventional seamless pipe manufacturing process that goes through a piercing rolling machine and then a drawing rolling machine.

In a clad tube manufactured through such a manufacturing process,
The laminated material (the one with the larger cross-sectional area is called the base material and the one with the smaller cross-sectional area is called the laminated material) is at most about 2 mm thick, and it is not possible to manufacture a clad tube with a thinner laminated material. difficult. This is because if the laminated material is made thinner than 2 mm, the laminated material will break during manufacturing (rolling).

Further, for example, in order to obtain a thin clad tube having a laminated material thickness of 0.3 mm or less, it is conceivable to manufacture the clad tube obtained by the above method by cutting the laminated material side by machining. However, even if the dimensional accuracy of rolled material is usually good,
Since it is 0.2 mm, when cutting by machining, there is a possibility that a part where the laminated material is missing may occur. Further, it is impossible to perform cutting work on the inner surface of a long pipe.

Therefore, it is difficult to manufacture a very thin clad tube having a laminated material thickness of 0.3 mm or less by the conventional technique.

In addition, when a metal tube made of an intermetallic compound is manufactured by an ordinary tube manufacturing method (such as the above-mentioned Mannesmann tube manufacturing method or hot extrusion method), there is a problem that surface defects occur in the material. Therefore, it is difficult to join other metal materials to these to form a clad tube.

(Problems to be Solved by the Invention) As described above, the conventional manufacturing method has not found a method for manufacturing a clad metal tube in which a very thin mating material having a thickness of 0.3 to 0.05 mm is bonded to one side or both sides.

Therefore, a general object of the present invention is to provide a method for producing a clad metal tube in which a very thin laminated material having a thickness of, for example, 0.3 to 0.05 mm is joined to the inner surface, outer surface or inner / outer surface of a base material.

A more specific object of the present invention is to provide a method for producing a clad metal tube in which the base material is an intermetallic compound alloy.

By the way, although stainless steel pipes are mainly used for pipes of chemical plants, heat exchange devices, etc., there are cases where holes are partially formed due to local corrosion. On the other hand, at present, repairs are carried out entirely or by replacing most of the piping, but this raises the problem that repair work costs and material costs are high and repair costs are high. ing.

However, at present, an effective method for repairing a partial defect in the pipe has not been found, and therefore, it is convenient if there is a method capable of performing partial repair. As a realistic method for this, bring a pipe made of a shape memory alloy pipe smaller than the inner diameter of the pipe to the corroded part, restore the shape and fix the part that attaches this pipe to the inner surface of the pipe A method has been proposed. However, depending on the type of fluid flowing in the pipe, the shape memory alloy does not guarantee sufficient corrosiveness. As a method of solving this, if a clad tube made of stainless steel on one side is used, a shape memory tube having high corrosion resistance can be obtained.

Therefore, another more specific object of the present invention is to provide a method for manufacturing a shape memory alloy clad tube using a corrosion resistant material such as stainless steel as a composite material on one or both sides, and a method for repairing piping using the same. is there.

(Means for Solving the Problems) In order to achieve the above-mentioned object, the present inventor has conducted extensive studies, and as a result, confirmed the following matters and completed the present invention based on them.

In order to manufacture a clad metal tube having a thin laminated material, first, a clad material having a multi-layer structure is manufactured, and then an unnecessary layer (portion) is removed by, for example, acid dissolution, which is a target (composite material thickness / The outer diameter of the composite material is 0.02 or less, and the (cross-sectional area of the composite material / total cross-sectional area) ratio is 0.25 or less.
It is possible to manufacture a clad tube with a thin laminated material of 3 mm or less. Because it does not rely on mechanical means such as cutting,
It is possible to completely remove the unnecessary layers while leaving the necessary layers.

In the case of difficult-to-machine materials such as intermetallic compound alloys, it is possible to suppress the occurrence of defects such as surface flaws by processing with an intermetallic compound alloy coated using a soft-working material such as carbon steel to prevent intermetallic compound The molding process can be easily performed.

Furthermore, it is difficult to clad NiTi-based shape memory alloys, which are alloys of intermetallic compounds, and stainless steels or Ni-based alloys, but the base material is NiTi-based shape memory alloys, and the joining material is stainless steel or Ni. A clad tube constituent material, which is a base alloy and, if necessary, with a Ta or Nb layer interposed as an intermediate material, can be easily clad by coating the inner and outer surfaces with a soft working material such as carbon steel before working. It will be possible.
Therefore, the characteristics of the shape memory alloy and the excellent corrosion resistance of stainless steel and the like can be used together, and it can be used as a repairing material for pipes in a more severe corrosive environment.

That is, the present invention made based on the above matters,
From that one side, the inner or outer surface of the base material or
In a method of manufacturing a clad metal tube in which a mating material having a thickness of 0.3 mm or less is joined to both outer surfaces, a tube made of a mating material is laminated on the inner surface or outer surface of the base material tube or both inner and outer surfaces to form a clad tube material. , The outer surface and the inner surface of the clad tube material are coated with a soft-working material to form a clad-assembled rod or tube, and then the clad rod or tube is heated to perform hot working, and each joining surface is diffusion-bonded. Then, the method is a method for producing a clad metal pipe, characterized in that the soft-worked material on the inner and outer surfaces is removed with an acid.

In a preferred embodiment of the present invention, the base material is 50 at% Ni.
It may be made of a shape memory alloy such as −50 at% Ti, and the composite material may be made of stainless steel or a Ni-based alloy. This is useful as a pipe material for pipe repair.

When a Ni-Ti alloy is used as the shape memory alloy, it is also a type of intermetallic compound alloy, so coating with a carbon steel layer as a protective material improves the workability of difficult-to-machine materials and forms a clad. It has both the significance of improving the corrosion resistance.

A Ta or Nb layer may be interposed between the base material and the composite material in order to further promote the clad formation of the base material and the composite material.

Incidentally, even in the past, a method of forming a work material coated with a mild steel material when forming a difficult-to-process material is performed, for example, in the field of powder metallurgy. This is for clad formation, and the idea of plastic working is different.

That is, in the case of the present invention, the additional shearing deformation that occurs during processing is positively utilized to promote diffusion bonding at the bonding interface.

(Operation) The configuration and operation of the present invention will be described more specifically with reference to the accompanying drawings.

First, the steps of the method according to the present invention are as follows, taking the case of coating with carbon steel and hot extrusion as an example.

Assembly process-> degassing process-> end welding process-> heating process-> hot extrusion / diffusion bonding process-> carbon steel (pipe) melting and removal process.

(1) Assembly Process: Use of Multi-Layered Clad Material Since the thickness of the laminated material is very thin, if the laminated material directly contacts a tool (roll, die, mandrel, etc.), it may break or be broken. In order to avoid this, it is necessary to interpose a protective carbon steel layer so that the laminated material does not come into direct contact with the tool.

When the base material is an alloy of intermetallic compounds such as NiTi alloy, it is an efficient method to wrap it with carbon steel in order to avoid cracks during processing.

Therefore, carbon steel is used for the outermost layer and the inner layer or the core material to obtain a multilayer structure clad material. And, carbon steel is used because it can be removed relatively easily with an acid, it can be processed at high temperatures, and it can be easily machined, welded, etc., and the clad material can be easily assembled. Is.

(2) Deaeration step: Once the clad material has been constructed, the joint surface is evacuated and deaerated to, for example, about (2-3) × 10 ⁻⁴ Torr.

(3) Edge welding process After degassing, electron beam welding (EBW) is used to perform edge welding to prevent oxidation of the joint surface.

FIG. 1 is a schematic view showing a cross section of the clad tube assembly blank 10 after the end welding is completed. In the illustrated example, a stainless steel layer 14 is provided around a carbon steel rod 12, and a NiTi-based alloy layer 16 and a carbon steel layer 17 are provided on the outermost shell with a Ta or Nb layer 15 interposed therebetween. A carbon steel stop plate 18 is also provided on the end face portion, and the periphery is welded by, for example, EBW.

(4) Heating step: Next, the clad material thus obtained is heated to a high temperature of about 950 ° C. when the base material is a Ni—Ti alloy, for example. Since both the inner and outer surfaces are covered with carbon steel, the joint surface of the clad metal pipe is not exposed to an oxidizing atmosphere and the joint surface is kept clean.

(5) Hot extrusion / diffusion bonding process: After the multilayer structure clad material is manufactured in this manner, hot working is performed to perform diffusion bonding to obtain a multilayer structure clad material. The hot working process will be exemplified as follows, when the assembly material is divided into a case of a raw tube and a case of a raw rod.

Multi-layer clad tube: Seamless pipe manufacturing process that goes through a piercing and rolling mill and then a drawing and rolling mill. Seamless pipe manufacturing process by hot extrusion and hot isostatic pressing. Multi-layer clad rod: Bar material produced by continuous rolling in a row of rolling mills. Manufacturing process Bar material manufacturing process by forging Hot extrusion, bar material manufacturing process by hot isostatic pressing Bar material manufacturing process by inclined rolling can be considered, but not limited to this, other methods or combinations of the above methods, etc. Conceivable.

(6) Carbon steel (pipe) melting and removing step: The thickness of the laminated material is very thin, for example, 0.3 to 0.05 mm, so when trying to remove unnecessary layers (parts) by machining, the precision of machining and the dimensions of the clad material Due to its precision, it is highly possible that the joining material will also be removed. However, if an unnecessary carbon steel portion is dissolved and removed with an acid, a very thin layer of the composite material can be left. Examples of acids that can be used are 70
An example is a 10-30% nitric acid aqueous solution heated to about ℃.

FIG. 2 (a) shows a case of a multi-layer clad metal pipe 20. When the carbon steel layer 22 on the inner and outer surfaces is acid-dissolved, it changes in the direction shown by the arrow in the figure to form a thin laminated material on the inner surface of the base material pipe 26. A clad metal tube 30 with a layer 28 is obtained.

FIG. 2 (b) shows a case of a multi-layer clad metal rod 40. When the carbon steel layer 42 on the inner and outer surfaces is acid-dissolved, it changes in the direction shown by the arrow in the figure to form a thin laminated material layer on the inner surface of the base material 44. A clad metal tube 50 with 46 is obtained. Prior to the removal of the internal carbon steel, the carbon steel as the core material may be perforated if necessary.

According to another preferred embodiment of the present invention, a Ni-Ti-based shape memory alloy is used as the base material, but as the other shape-memory alloy, a Cu-Ti-based alloy and a Ni-Ti engagement metal are generally used. Are known. Ni-Ti alloys are preferable to Cu-Ti based alloys because they have excellent properties such as corrosion resistance, ability to recover against external force and heat, recovery rate, and life.

The Ni-Ti-based shape memory alloy used here contains 47 to 60 atom%
It consists of Ni and the balance Ti, but part of T: is Cu, V, Mo, C
A composition in which one or more elements such as r, Al, Co and Fe are substituted may be used. However, these amounts are at most 5 atom% or less.

When a shape memory alloy is used as the base material, stainless steel or a Ni-based alloy is preferably used as the mating material, but the Ni-Ti alloy does not have sufficient corrosion resistance to acid, so this is recommended. To compensate, stainless steel or Ni-based alloy with excellent corrosion resistance is used.

The thickness of the laminated material is 0.02 or less in terms of the ratio (thickness of laminated material / outer diameter of laminated material),
The ratio (cross-sectional area of laminated material / total cross-sectional area) of 0.25 or less is
This is to avoid this because the shape hardly returns when the thickness of the laminated material is large.

In the case of the above materials, the bonding strength may not be sufficient, and in such a case, it is effective to interpose a Ta or Nb layer between the base material and the laminated material.

By using the Ta and Nb layers, it is possible to improve the joint strength at the joint interface between the base material and the laminated material and at the same time improve the corrosion resistance at the joint interface.

Furthermore, the present invention in which a clad material is manufactured by coating with a soft-working material, and after the diffusion bonding, the soft-working material is removed to clad a thin laminated material, a rod / wire material, a shape material,
It goes without saying that it can be applied to plate materials and the like.

(Example) Next, the Example of this invention is described. In this example, the base material is a shape memory alloy which is an intermetallic compound alloy, but the present invention is not limited thereto.

First, as shown in FIG. 2 (b), a clad assembly material was manufactured with the following constitution. The unit is mm.

[Material I] Carbon steel pipe: 67φ × 6.9t Ni-Ti alloy pipe: 53φ × 2.75t SUS316L pipe: 47.3φ × 0.9t Carbon steel rod: 45.3φ [Material II] Carbon steel pipe: 67φ × 6.9t Ni-Ti alloy Pipe: 53φ × 2.75t Ta foil: 0.1t SUS316L Pipe: 47.0φ × 0.9t Carbon steel rod: 45.0φ Machined to the above dimensions, (2-3) × 10 ^-4 as shown in Fig. 1. Both ends were sealed and welded by electron beam welding (EBW) in a Torr vacuum chamber to produce a clad assembly material.

After heating these assembled materials to 950 ° C., the diameter was 25 mm by hot extrusion. And with 18% nitric acid as a protective material
Dissolving and removing the outer carbon steel layer, this time diameter 19.2 x 0.8t
A 0.25t Ni-Ti alloy / SUS316L clad tube was obtained.

Here, a 50 atom% Ni-50 atom% Ti alloy was used for the Ni-Ti alloy, and a low carbon steel was used for the carbon steel.

The joint strength of the joint interface between Ni-Ti alloy and SUS316L in a clad tube with a diameter of 25 mm is the shear strength, for material I: 14.
0, 14.6 (kgf / mm ² ), Material II: 17.5, 18.1 (kgf / m
m ² ).

Furthermore, when the joint interface was observed with a microscope, material I
Where is a void (very small unbonded part)
However, no defect was found in Material II.
If there is a void at the joint, it will be the starting point and erosion will proceed, so there should be no void. From these, it was found that it is preferable to interpose Ta as an intermediate layer in order to improve the bonding strength and maintain the corrosion resistance. Moreover, almost the same result was obtained by using Nb in addition to Ta.

The diameter of this 19.2 mm clad tube was drawn by cold die drawing.
18.5mm, then when heated to 200 ℃, diameter 18.9mm
The outer diameter has recovered. As described above, if the laminated material is made extremely thin, it is possible to form a shape memory clad tube.

(Effects of the Invention) The present invention is configured as described above, and after the inner and outer layers are protected with carbon steel to form a multilayer clad material, the protective material is removed to produce a clad tube. Since the laminated material can be made very thin,
-Since the Ti alloy is used, it can be used as a shape memory clad tube. Further, since stainless steel is used for the laminated material, it has excellent corrosion resistance and is extremely useful industrially.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view of a multi-layer clad material according to an embodiment of the present invention; and FIGS. 2 (a) and 2 (b) are carbon steel of a multi-layered clad material of the present invention for a pipe and a bar, respectively. It is a schematic explanatory drawing which shows the state before and after dissolution removal. 10: Clad assembled tube, 12: Carbon steel bar material, 14: Stainless steel layer, 15: Ta or Nb layer, 16: NiTi alloy layer, 17: Carbon steel layer, 18: Stop plate

Claims (5)

[Claims] 1. A method for producing a clad metal pipe in which a joining material is joined to an inner surface or an outer surface of a base material or both inner and outer surfaces, wherein a pipe made of the joining material is formed on the inner surface or outer surface of the base material tube or both inner and outer surfaces. The clad tube material is laminated to form a clad tube material, and the outer surface and the inner surface of the clad tube material are coated with a soft-working material to form a clad assembled raw rod or a raw tube, and then the clad assembled raw bar or the raw tube is heated to perform hot working. A method for producing a clad metal pipe, which comprises performing diffusion bonding on the respective joint surfaces, and then removing the soft-worked material on the inner and outer surfaces with an acid. 2. The method for producing a clad metal tube according to claim 1, wherein the base material is made of an intermetallic compound alloy. 3. The method for producing a clad metal tube according to claim 1, wherein the base material is made of a Ni—Ti type shape memory alloy, and the composite material is made of stainless steel or a Ni-based alloy. 4. The thickness of the composite material is 0.02 or less in the ratio (composite material thickness / outer diameter of the composite material), and in the (composite material cross-sectional area / total cross-sectional area) ratio.
It is 0.25 or less, The manufacturing method of the clad metal tube in any one of Claim 1 thru | or 3. 5. The method for producing a clad metal tube according to claim 1, wherein a Ta or Nb layer is interposed between the base material and the laminated material.