JPH08109405A - Production of wear resistant composite pipe - Google Patents

Abstract

PURPOSE: To produce a composite pipe having a fine and hard structure and excellent wear resistance by sintering wear resistant high alloy powder in a solid phase by a capsule HIP method into a pipe consisting of a stainless steel or carbon steel. CONSTITUTION: The bottom end of the pipe 10 consisting of the stainless steel or the carbon steel is closed and a core 11 is put therein. An eccentricity preventive ring 12 adequately formed with holes on the circumference is put into the pipe at the time of inserting the core 11. The high alloy powder 13 (stellite powder, etc.) is then packed between the core 11 and the pipe 10 while proper vibration is applied thereon and a stainless steel cap 14 is put on the upper part of the pipe 10 and is circumferentially and hermetically welded to form a capsule. The capsule 17 is evacuated to about <=10<-5> Torr by deaeration from the discharge port 15 of the capsule 17 in this state. The discharge 15 is then press welded to completely seal the capsule and the capsule is subjected to the HIP treatment. The HIP treatment is executed for about 1 to 4 hours at about 1000 to 1200 deg.C under about 1000 to 1500atm. As a result, the wear resistant composite pipe built up with the high alloy powder 13 is obtd. on the inside surface of the pipe 10. The pipe is used for transportation, etc., of powder and granular materials.

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 wear resistant composite pipe applicable to a pipe used for transportation of powder and granules.

[0002]

2. Description of the Related Art When a powdery or granular material is transported by a fluid (gas or liquid), the inner surface of the pipe to be used is abraded, so that a wear resistant material may be welded to the inside by pipe overlay welding (referred to as PTA). Has been done. In this welding, a plasma welding torch is inserted into the inner surface of a tube made of stainless steel or carbon steel, which has wear resistance and, if necessary, heat resistance, corrosion resistant powder of a high alloy material or The rod-shaped material is melted by plasma and built up on the inner surface of the tube.

[0003]

However, there are the following problems in the overlay welding of pipes according to the conventional example. It is necessary to put a plasma welding torch used for overlay welding in a pipe for welding, and as a result, the pipe to be used needs to have an inner diameter larger than a certain value, which is not applicable to small diameter pipes. Multilayer welding is required to increase the build-up thickness of wear-resistant material in order to extend the life, but cracks may occur or interlaminar cracking may occur due to thermal stress when performing multilayer welding. However, even if welding is possible, complicated heat treatment steps such as preheating or postheating are required. In pipe overlay welding, since the high alloy to be overlayed is once melted, it is not possible to overlay weld a precipitation hardening cemented carbide having extremely high hardness. Therefore, according to the current technology, materials in the range that are not cracked by overlay welding are overlay welded, resulting in insufficient hardness and insufficient wear resistance. The present invention has been made to solve the above problems,
An object of the present invention is to provide a method for manufacturing a wear-resistant composite pipe in which the thickness of the inner lining can be freely controlled, and moreover, cracks and the like do not occur in the conventional construction.

[0004]

A method according to the above-mentioned object.
In the method for producing the wear-resistant composite tube described above, wear-resistant high alloy powder is solid-phase sintered by a capsule HIP (hot isostatic pressing) method inside a tube made of stainless steel or carbon steel. . Here, as the wear-resistant high alloy powder, for example, a cobalt-based alloy having heat resistance and wear resistance (for example, stellite) is preferably used, but other high alloy powders having wear resistance may be used. The present invention is applicable.

[0005]

In the method for manufacturing the wear resistant composite pipe according to claim 1, the high precipitation powder having fine crystal grains and fine precipitates is subjected to solid phase sintering by the HIP method without being melted to obtain fine precipitation. A material having a large number of objects is obtained inside the pipe, which makes it possible to increase the alloying and hardness of the overlaid metal. Further, these solid-phase sintered materials make the precipitate finer than the molten structure and suppress the precipitation at the grain boundaries, so that mechanical properties such as strength and toughness can be greatly improved. Further, since the HIP method raises the temperature lower than the melting point of the material and the temperature of the material part of different kinds substantially evenly, it is possible to reduce the thermal stress generated due to the difference in thermal expansion coefficient between different kinds of materials. Since the solid-phase joining is performed by the HIP method, the thickness of the buildup on the inner surface of the pipe can be freely controlled, and this portion has a homogeneous structure. Note that these solid-phase sintered build-up composite pipes can be bent at a high temperature of 600 ° C. or higher, and can also be used as bend pipes and the like.

[0006]

EXAMPLES Next, examples embodying the present invention will be described to provide an understanding of the present invention. FIG. 1 is an explanatory view of a method for manufacturing a wear resistant composite pipe according to an embodiment of the present invention, and FIG. 2 is a plan view of a wear resistant composite pipe according to an embodiment of the present invention and a conventional method. FIG. 3 is a graph showing a comparison of the wear degrees of the wear-resistant composite pipe according to the example of the present invention and the wear-resistant composite pipe according to the conventional example, and FIG. It is explanatory drawing which shows another manufacturing method.

As shown in FIG. 1, one end (that is, the lower end) of a pipe 10 made of stainless steel or carbon steel to be built up on the inner surface is closed and a core 11 is put inside. It is preferable to use the core 11 that is hard to bond to the alloy powder to be built up such as ceramics, but even if it is to be bonded to the alloy powder for build-up such as carbon steel, it should be removed by machining after HIP treatment. Good. When inserting the core 11, an eccentricity prevention ring 12 is inserted to form a built-up layer having a uniform thickness. This eccentricity prevention ring 12 is appropriately formed with holes around it so that the high alloy powder can be introduced from above.

In this state, high alloy powder 13 (for example, stellite powder) is filled between the core 11 and the tube 10.
In this case, if the packing density is low, the powder portion will be largely deformed and the buildup thickness will be difficult to control. After the filling of the high alloy powder 13 is completed, the stainless steel lid 14 is put on the upper portion of the tube 10 and the surroundings are hermetically welded (which is encapsulated). In this state, the exhaust port 15 of the capsule 17 is connected to a vacuum pump to perform deaeration, a vacuum of, for example, 10 ⁻⁵ torr or less is made, and the exhaust port 15 is pressure-bonded to completely seal it. To do. The conditions of this HIP treatment are a temperature of about 1000 to 1200 ° C. and a pressure of 1000.
The processing time is about 1 to 4 hours.

By the above process, the high alloy powder 13 is diffusion bonded to the tube 10 and the mutual powders are diffusion bonded,
The high alloy powder 13 is built up on the inner surface of the tube 10. Table 1 shows the hardness of the inner surface of the pipe 10 which was built up by the above HIP treatment and the pipe which was built up by the PTA treatment by the conventional method.

[0010]

[Table 1]

As shown in Table 1, the high alloy powder corresponding to Stellite # 1 was cracked by PTA treatment and could not be built up, but it was possible by the method of this example.
FIG. 2A shows the structure that was built up by the HIP process using the materials of the above-described examples, and FIG. 3B is the structure that was built up by the PTA process. As is clear from FIG. 2, when the HIP treatment is performed, rapid cooling causes atomized powders having finer crystal grains to be bonded to each other, resulting in a finer structure as compared with the case of welding. I understand that. Further, FIG. 3 shows the results of abrasion tests of the wear resistant composite pipe manufactured by the method of the present invention and the wear resistant composite pipe manufactured by the conventional method. It can be seen that the wear-resistant composite pipe of the example of the present invention is excellent.

FIG. 4 shows a method of manufacturing a wear resistant composite pipe according to another embodiment of the present invention, in which the pipe 1 without core is used.
A thin stainless tube 16 is arranged inside the 0, thereby forming a sealed capsule 17. In this case, the stainless steel pipe 16 is joined to the built-up portion on the inner side, but when it is used as a wear resistant pipe, it need not be particularly removed. Therefore, Table 2 shows the results of comparison between the wear-resistant composite pipe manufactured by the method of the present invention and the wear-resistant composite pipe manufactured by the conventional PTA method from the results of various experiments. The wear-resistant composite pipe according to
It can be seen that it has excellent wear resistance and there are no restrictions on construction.

[0013]

[Table 2]

[0014]

As is apparent from the above description, the wear-resistant composite pipe according to the first aspect of the present invention comprises a wear-resistant high alloy powder capsule HI inside a pipe made of stainless steel or carbon steel.
Since solid-phase sintering is performed by the P method, even when the same material is overlaid, the structure is finer than that of the conventional weld overlay, and the tube is hard and has excellent wear resistance. Further, since the welding torch is not used, the method of the present invention can be applied to a small diameter pipe, and the buildup thickness is not particularly limited.

[Brief description of drawings]

FIG. 1 is an explanatory view of a method for manufacturing a wear resistant composite pipe according to an embodiment of the present invention.

FIG. 2 is a micrograph showing a structure (A) of a built-up portion of a wear-resistant composite pipe according to an embodiment of the present invention and a structure (B) of a built-up portion of a wear-resistant composite pipe according to a conventional method.

FIG. 3 is a graph showing a comparison of the degree of wear of the wear resistant composite pipe according to the example of the present invention and the wear resistant composite pipe according to the conventional example.

FIG. 4 is an explanatory view showing another manufacturing method.

[Explanation of symbols]

 10 Tube 11 Core 12 Eccentricity Prevention Ring 13 High Alloy Powder 14 Lid 15 Exhaust Port 16 Stainless Steel Tube 17 Capsule

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Shinji Shima Shima 46-59, Nakahara, Tobata-ku, Kitakyushu, Fukuoka Prefecture Machinery & Plant Division, Nippon Steel Corporation (72) Takahiko Oguro Fuji, Hirohata-ku, Himeji-shi, Hyogo Prefecture No. 1 town Shin Nippon Steel Co., Ltd. Hirohata Works

Claims (1)

[Claims] 1. A method for producing a wear-resistant composite pipe, characterized in that wear-resistant high-alloy powder is solid-phase-sintered by a capsule HIP method inside a pipe made of stainless steel or carbon steel.