JPH108111A - Manufacturing method of wear resistant composite pipe - Google Patents

Abstract

(57) [Summary] PROBLEM TO BE SOLVED: To provide a wear-resistant high alloy element in a manufacturing process
Transport of powdered fluid to prevent cracking of material and improve production yield
Manufacture of wear-resistant composite pipe applicable to pipes used for transportation
To provide a fabrication method. SOLUTION: The coefficient of thermal expansion from normal temperature to 500 ° C. is 9
× 10^-6~ 15 × 10^-6Is stainless steel or carbon
Austenitic wear-resistant high alloy on the inner surface of steel tube
When powder is solid-phase bonded by capsule HIP method,
Ferrite-Aus
Tennite duplex stainless steel or stainless steel
Coefficient of thermal expansion from room temperature to 500 ° C on the inner surface of stainless steel pipe
Is 9 × 10 ^-6~ 15 × 10^-6Austenitic resistance
Solid phase bonding of wearable high alloy powder by capsule HIP method
The capsule core material to control the inner diameter
Stainless steel or ferrite-austenite
And duplex stainless steel, in contact with wear-resistant high alloy powder
It is a ferrite-forming element on the surface of these stainless steels
Cr coating 0.01mm to 0.5mm
A method for producing a wear-resistant composite pipe, comprising:

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 pipes used for transporting powdery fluids.

[0002]

2. Description of the Related Art Conventionally, when powder fluid is transported by gas or liquid, the inner surface of a pipe used undergoes severe abrasion due to collision of the powder fluid, and the flow velocity and flow rate fluctuate due to a change in the pipe diameter or shape. And, in severe cases, punctures, which have a significant effect on plant operation. In order to solve such a problem, the inventors of the present invention have applied for a solid-state joining of a wear-resistant high alloy powder to the inner surface of a tube made of stainless steel or carbon steel by a capsule HIP method in Japanese Patent Application No. 6-275791. We are developing technology to do it.

The inventors have proposed a capsule method having a core 1 as shown in FIG. 1 as a pipe manufacturing method in the above invention. By preventing dimensional deformation of the inner surface of the pipe by sintering, after sintering,
The inner diameter accuracy is ensured by easily removing the core by machining. This method is intended only for sintering, and it is possible to use a hollow sleeve-shaped capsule as shown in FIG. 2 instead of the core method. However, in this method, capsule deformation due to powder shrinkage occurs on the inner surface side. In order to secure the inner diameter accuracy, it is necessary to cut a part of the wear-resistant and high-hardness portion, which leads to an increase in cost.

[0004]

SUMMARY OF THE INVENTION Core type capsules
As described above, this method is not excellent in terms of securing the inner diameter accuracy.
However, carbon steel with transformation characteristics is used as the core material.
If it is used as a wear-resistant alloy on the inner surface of the pipe,
The coefficient of thermal expansion at 9 ° C is 9 × 10^-6More than 15 × 10 ^-6Less than
The hardness is 550 Hv or more and the room temperature elongation is 1% or less.
Austenitic wear-resistant high alloy
The problem that cracks often occur during construction
There was found. The present invention is based on the
Prevent cracking of gold material and improve manufacturing yield
It is the purpose.

[0005]

To achieve the above object, a method for producing a wear-resistant composite pipe is described in which stainless steel having a coefficient of thermal expansion from room temperature to 500 ° C. of 9 × 10 ⁻⁶ to 15 × 10 ^−6. Or, when the austenitic wear-resistant high alloy powder is solid-phase bonded to the inner surface of a pipe made of carbon steel by the capsule HIP method, the material of the capsule core material for controlling the inner diameter is ferrite-austenite duplex stainless steel,
Alternatively, on the inner surface of a stainless steel pipe,
When the austenitic wear-resistant high alloy powder having a coefficient of thermal expansion of 9 × 10 ⁻⁶ to 15 × 10 ⁻⁶ is solid-phase bonded by capsule HIP method, the material of the capsule core material for controlling the inner diameter is ferrite. Stainless steel or ferrite-austenite duplex stainless steel, characterized in that the surface of these stainless steels in contact with the wear-resistant high alloy powder is coated with Cr, which is a ferrite forming element, in a thickness of 0.01 mm to 0.5 mm. is there. As the austenitic wear-resistant high alloy powder according to the present invention, a material having no transformation, such as a precipitation hardening type Co-based alloy, a Ni-based alloy, or stainless steel, is targeted.

Hereinafter, the present invention will be described in detail. The present inventors have examined in detail the cause of cracking of the wear-resistant high alloy material in the manufacturing process described above, and found that the residual stress is derived from the difference in thermal expansion between the core material and the precipitation-hardened austenitic wear-resistant high alloy. I found that. When the core material is carbon steel, the core material undergoes pearlite transformation and remarkably expands during HIP treatment cooling, so that excessive tensile stress is applied to the austenitic wear-resistant high alloy, and the large tensile stress increases within 24 hours after HIP sintering. Partial cracking occurs. Further, in the case of using austenitic stainless steel, a compressive stress acts on the austenitic abrasion-resistant high alloy, so that cracks are less likely to occur, but the machinability at the time of removing the core is poor, and the production cost is significantly increased.

In view of these phenomena, the present invention minimizes the difference in thermal expansion between a precipitation hardening austenitic abrasion resistant high alloy as a core material in contact with the abrasion resistant high alloy powder and minimizes residual stress. Ferrite-forming element Cr on the surface of ferritic-austenite duplex stainless steel or ferritic stainless steel 0.01 mm to 0.5 mm
It has been found that the method of coating is optimal. This is because, in the case of ferritic stainless steel, the austenite forming element of the austenitic wear-resistant high alloy powder diffuses to the surface of the ferritic stainless steel as the core material during HIP sintering, and as a result, HIP cooling occurs at the interface diffusion part. This is intended to prevent the occurrence of martensite deformation at times, and thereby the occurrence of cracks.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is an explanatory view of a method for producing a wear-resistant composite pipe according to an embodiment of the present invention. Table 1 shows the material combinations of the examples, and Table 2 shows the test results. In the embodiment of the present invention, as shown in FIG. 1, one end of a stainless steel tube 1 whose inner surface is coated with a sintered hard layer is closed, and a core 2 is inserted into the inner surface. Powder 3 between core 2 and stainless steel tube 1
(For example, stellite powder). After filling the powder, a lid is attached to the upper part of the pipe by welding. In this state, the inside of the capsule 4 is evacuated from the degassing pipe 5 welded to the capsule 4 and completely sealed by pressing the degassing pipe 5 under a vacuum of, for example, 10 ^-5 atm or less. HIP processing is performed. After the HIP treatment, the core 2 is removed by machining to obtain a composite pipe. Reference numeral 6 denotes a core surface treatment unit, and reference numeral 7 denotes a welding seal.

Table 1 shows the core materials and core surface treatments when performing encapsulation. In this embodiment, after vacuum sealing as described above, 1180 ° C., 150MP
a, Processing was performed under HIP conditions for 3 hours. Table 2 is HIP
FIG. 4 shows the results regarding the presence or absence of breakage of the sintered hard layer after sintering and before machining. (1) As shown in Comparative Example 7, when the core is made of general carbon steel, a tensile stress acts in the circumferential direction of the stellite layer due to the expansion of the core due to the pearlite transformation during cooling.
Cracks occurred within hours.

(2) As shown in Comparative Example 6, when the core is made of SUS304, which is an austenitic stainless steel, the core has a coefficient of thermal expansion larger than that of stellite # 1, so that a circle of stellite # 1 layer is formed. Compressive stress was applied in the circumferential direction to prevent cracking after HIP, but workability was significantly impaired, and removal of the core became difficult. (3) When the core is made of SUS405, which is a ferritic stainless steel, as shown in Comparative Example 4, or as shown in Comparative Example 5, the core is made of SUS405, and an austenite forming element is formed on the surface. When Ni was plated, Ni diffused to the surface of the core during HIP treatment cooling, causing martensitic transformation. With this, HIP
Although subsequent cracking did not occur, the workability was significantly impaired, the core was difficult to remove, and a crack was generated from the martensite portion during processing and propagated to the stellite # 1 hard layer.

(4) As shown in Comparative Example 1, the core was SU
When the surface was plated with Cr, which is a ferrite-forming element, after being manufactured in S405, it was possible to prevent martensitic transformation of the core surface during HIP treatment cooling and to prevent cracking. The machinability was also good. (5) As shown in Comparative Examples 2 and 3, the core was made of ferrite.
SUS329j, austenitic duplex stainless steel
And ferrite forming element C on the surface
When plated with r or when the core was made of SUS329j1, there was no crack after HIP treatment, and the machinability was good.

[0012]

[Table 1]

[0013]

[Table 2]

[0014]

As described above, in the core type capsule according to the present invention, in which the inner diameter accuracy is easily ensured, by specifying the core material, it is possible to prevent cracks during the production of the abrasion resistance of the inner surface of the tube. As a result, the manufacturing yield can be improved.

[Brief description of the drawings]

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

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Stainless steel pipe 2 Core 3 Powder 4 Capsule 5 Degassing pipe 6 Core surface treatment part 7 Weld seal

Claims (2)

[Claims] 1. A pipe made of stainless steel or carbon steel having a coefficient of thermal expansion of 9 × 10 at room temperature to 500 ° C.
^When the austenitic wear-resistant high alloy powder having a diameter of ^-6 to 15 × 10 ^-6 is solid-phase bonded by the capsule HIP method, the core material of the capsule for controlling the inner diameter is a ferrite-austenite duplex stainless steel. A method for producing a wear-resistant composite pipe, comprising: 2. The inner surface of a tube made of stainless steel has a coefficient of thermal expansion from room temperature to 500 ° C. of 9 × 10 ⁻⁶ to 15 × 1.
0 when solid-phase joined by austenitic wear resistant high-alloy powder is ^-6 capsule HIP method, the capsule core material for performing inner diameter control and ferritic stainless steel, in contact with the wear-resistant high-alloy powder thereof Cr, which is a ferrite forming element, is deposited on the surface of
A method for producing a wear-resistant composite pipe, which is coated with 0.5 mm.