JPS61223106A - Production of high alloy clad product - Google Patents

Abstract

PURPOSE:To produce easily a clad product of a base metal and high alloy by holding a high alloy powder layer on the surface of the base metal then subjecting the same to heating and deaerating followed by heating to the solidus line temp. of the high alloy powder or above and pressurizing simultaneously the same by gas. CONSTITUTION:A case 2 and cap 3 made of a thin sheet such as steel sheet are welded 4 to the surface of the base metal 1 for the clad product. The high alloy powder 5 for forming the clad layer is packed into the space between the surface of the base metal 1 and the case 2 so that the powder 5 is held on the surface of the base metal 1. The inside of the high alloy powder packed layer is evacuated to a vacuum and at the same time the base metal and powder are heated to about 600 deg.C by a heater 6, by which the gaseous components sticking to the high alloy powder are thoroughly removed. The assembly is put into a pressurizing vessel 7 after the vacuum suction port is closed and while the assembly is heated to the solidus line temp. of the high alloy powder or above by a heater 6, an inert gas such as Ar or N2 is forced into the vessel under 50-500atm. pressure and is held for <=15min under such temp. The assembly is then cooled and the case 2 and cap 3 are removed therefrom. The high alloy clad product having the excellent resistant to corrosion, heat and wear is obtd.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention provides a clad product having a high alloy layer with excellent corrosion resistance, heat resistance, and wear resistance C2 in a relatively compact and low cost manner. It relates to a manufacturing method.

<Prior art and its problems> In general, to manufacture products that require high corrosion resistance, high heat resistance, and high wear resistance, high-alloy steel containing alloying elements, as well as Ni-based and Co-based non-ferrous steels are used. High alloy materials are used.

However, these materials contain many expensive rare metals, which increases product costs, and depending on the composition, hot processing or machining may be difficult, or in extreme cases, hot processing may not be possible. However, there were some inconveniences.

For this reason, recently, a high alloy powder layer was retained on the surface of the metal base material (2. A high alloy surface was formed by solidifying this with hot isostatic pressing). There have also been proposals for cladding products that have these properties.

What are the clad products that make up this proposal?

1) To a body part (base material) made of a metal material whose solidus temperature is higher than that of the cladding layer, a thin plate case made of a material whose solidus temperature is also higher than that of the cladding layer is welded with a predetermined gap from the surface.

11) After filling the gap formed between the thin plate case and the body parts with the metal powder for the cladding layer, 2
111) The welded assembly is subjected to hot isostatic pressing.

iv) The thin plate case is removed by machining or pickling corrosion to obtain the final shape. According to this method, the use of expensive high alloys can be kept to a minimum and the cost can be reduced. A metal member with high functionality such as corrosion resistance, high heat resistance, and high wear resistance was obtained.

However, in the method for manufacturing high-alloy clad products as described above, the hot isostatic pressing treatment is performed at a heating temperature that is somewhat lower than the solidus temperature of the metal powder for the clad layer.

Pressure pressure: 1000-2000 atm, holding time = 1-
It requires severe conditions for two hours, and the extremely high degree of pressurization requires a specially constructed pressure vessel, so the larger the processing capacity, the greater the equipment cost, which is a major problem. Moreover, we had to accept the inconvenience that the processing time (high temperature and high pressure holding time) was as long as 1 to 2 hours. From these viewpoints, we aimed to find a method for manufacturing clad products with high alloy layers that have sufficiently excellent corrosion resistance, heat resistance, and wear resistance without using particularly expensive equipment and with high efficiency. I did some research.

When carrying out the method of making body parts made of high-alloy powder, if high-temperature heating above the solidus temperature of the powder is adopted, the powder will be in a semi-molten or molten state, so gas pressure will also be sufficient. achievable 50-5
Even under a relatively low pressure of 0.000 bar, the 100% dense high-alloy cladding layer, which has sufficiently satisfactory performance from powder with a filling rate of 60111 degrees, can be applied to the surface of body parts. formed over time.

This invention was made based on the above-mentioned knowledge.

The surface of the base material (= retaining a high-alloy powder layer, then heating and degassing it, then heating the powder layer to a temperature higher than the solidus temperature of the powder and pressurizing the powder layer to densify the powder layer) This makes it possible to manufacture high-alloy clad products with heat resistance and wear resistance in a relatively short period of time and at low cost.

It has the following characteristics.

Here, the types of "base material" and "high alloy powder" are not particularly limited, but high alloy powders whose solidus temperature is lower than the melting point of the base material are applicable. Of course. Also.

It is also preferable to use an inert gas as the gas for pressurization.

The heating temperature during pressurization may be any temperature that is higher than the solidus temperature of the applied high-alloy powder and lower than the melting point of the base material; however, depending on the scale of the equipment, ,
Considering processing time, cost, etc., it is recommended to adjust the temperature to a temperature higher than or equal to the solidus temperature of the high alloy powder and lower than the liquidus temperature.

Now, FIG. 1 shows an example of a series of steps for producing a high alloy clad product according to the method of the present invention. Hereinafter, the present invention will be explained in more detail with reference to FIG.

That is, the method of the present invention is as shown in Figure 1.

First, a body part (base body) 1 for a clad product is cast,
Forging 1 Manufactured by means such as machining (process @).

Then, at cladding processing temperatures, it does not react significantly with the high alloy powder or melt itself.

Materials that can remain airtight throughout the cladding process (
Weld the thin plate case 2 and lid 3 made of iron or steel (iron or steel is sufficient) (Work 81@).

Then, the gap formed between the surface of the body part 1 for blood products and the thin plate case 2 is filled with high alloy powder 5 for forming a cladding layer, and the high alloy powder is held on the surface of the body part. (of the process).

Next, as a pretreatment for the solidification process, a vacuum is drawn to remove gas components in the powder, and the powder is held for 10 minutes to 2 hours. In this case, in order to efficiently remove the gas components adhering to the powder surface and prevent the formation of harmful oxides during the solidification process, it is preferable to vacuum the powder while heating it to around 600°C with the heater 6. This is as stated above.

Note that this step is strongly recommended from the viewpoint of stabilizing the performance of the high-alloy cladding layer 6 product (step e).

Subsequently, the high alloy powder holder with the vacuum suction port closed is charged into the pressurized container 7 and heated to a temperature higher than the solidus temperature of the powder (preferably higher than the solidus temperature and lower than the liquidus temperature). , 50-5
00 atm gas atmosphere (for example, N gas atmosphere or Ar gas atmosphere) for 5 seconds to 15 minutes (Step 6J)
.

After the heating and pressurizing treatment is completed, the thin plate case 2 and lid 3 are removed from the processed product taken out from the pressurized container 7 by machining or pickling corrosion. Note that the reference numeral 8 in 1 drawing 6: indicates a machined blade (step ■).

Further, the shape is adjusted as necessary to make a high alloy brad product ([Co., Ltd.]).

This method is explained as a series of steps, and excellent effects can be obtained when applied to the manufacture of products that require corrosion-resistant and wear-resistant inner surfaces of complex shapes, such as valves.

Next, the present invention will be explained by examples.

<Example> First, outer diameter: 50-φ, inner diameter: 30-φ, length: 15
A low alloy steel pipe (base material) made of 0W 845C and high alloy powders A and B having chemical compositions as shown in Table 1 were prepared.

Next, in the same way as shown in FIG.
After welding a thin mild steel plate with a wall thickness of 1.2 va to a gap in the cage, the gap was filled with high alloy powder.

Further, the high alloy powder was vacuum degassed under the pretreatment conditions shown in Table 2.

After completing the pretreatment, the high alloy powder layer holding pipe with the vacuum suction port closed is placed in a pressurized container, and from now on, it will be subjected to densification treatment (heating and pressure treatment) under the conditions shown in Table 2. By attaching and then removing the mild steel thin plate by machining,
A high alloy Talarad pipe material was obtained.

Next, a part of the high alloy clad layer was cut out from the high alloy clad pipe material obtained in this manner.

When the degree of densification of the cladding layer was evaluated by microscopic observation, the same results as shown in Table 2 were obtained.

In addition, in Table 2, the evaluation of the degree of densification is O... No bow 2 bass part at all.

Δ...Slightly porous part, ×...Many porous parts It was implemented in three stages.

From the results shown in Table 2, it can be seen that according to Method C of the present invention, high-alloy brad products with good performance can be obtained at a high yield with a relatively small pressing force and in a short processing time. It is clear.

Furthermore, Figure 2 shows a microscopic structure photograph of the high alloy layer portion of a high alloy clad product obtained by processing under the same conditions as in Test No. 6 except that the Ar gas pressure was 300 atm. (Magnification: 100 times) However, as can be seen from Fig. 2, the method of the present invention: According to the method of the present invention, there are no pores at all, and therefore a clad product with a high alloy layer that is fully satisfactory in terms of corrosion resistance is stable. It is clear that this can be obtained by

<Overall Effects> As explained above, according to the present invention, a clad product having a high alloy layer with excellent corrosion resistance, heat resistance, and wear resistance can be manufactured efficiently at low cost, etc.
This brings about extremely useful effects industrially.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram showing a process example of a high alloy clad product according to the method of the present invention. FIG. 2 is a micrograph of a high alloy layer in a high alloy clad product according to the method of the present invention. 1... Body parts for clad products (base material), 2...
Thin plate coupe, 3...lid, 4...welded part,
5...High alloy powder. 6... Heater, 7... Pressurized container. 0 Death: Machined cutlery.

Claims (2)

[Claims] (1) After holding a high alloy powder layer on the surface of the base material, this is heated and degassed, and then the powder layer is heated to a temperature higher than the solidus temperature of the powder and gas is pressurized to densify the powder layer. A method for manufacturing a high-alloy clad product, characterized by performing the following steps. (2) The method for manufacturing a high alloy clad product according to claim 1, wherein the heating temperature during densification of the powder layer is set to be higher than the solidus temperature of the high alloy powder and lower than the liquidus temperature.