JPH02247367A - Plastic working method for b-containing co-base heat resisting alloy - Google Patents

Abstract

PURPOSE:To carry out the plastic working of a B-containing Co-base heat resisting alloy without dissipating B by subjecting an ingot of a Co-base alloy containing specific amounts of C, Cr, W, and B to blooming, hot working, process annealing, and final heat treatment at respectively specified temps. CONSTITUTION:An ingot of a B-containing Co-base heat resisting alloy prepared by melting and casting and containing, by weight, 0.02-0.25% C, 18.0-25.0% Cr, 13.0-17.0% W, and 0.001-0.1% B is subjected to blooming so as to be formed into a working stock, such as billet and slab. This working stock is subjected to hot working, such as hot forging and hot rolling. Then, the alloy stock is subjected to a repetition of process annealing, pickling, and cold working so as to be worked into small-diameter wire, thin-wall tube, thin sheet, etc., followed by final heat treatment, as necessary. In the above method, the above blooming, hot working, process annealing, and final heat treatment are carried out at 1000-1150 deg.C. By this method, the above alloy can be stably plastic-worked in the air without dissipating B, and the desired mechanical properties, such as high temp. creep characteristics, can be obtained.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a method for plastically working a processed material made of a B-containing Co-based heat-resistant alloy without reducing the boron content contained in the processed material. More specifically, C: 0.02-0.2596 Cr: 18.0-25.0% W: 13.0-17.0% B: 0. From a B-containing Co-based heat-resistant alloy containing OO1 to 0.1% as an essential component, B-containing fine wire rods with a diameter of 8III11 or less, thin plates with a plate thickness of 5 or less, thin-walled tubes with a wall thickness of 5III11 or less, etc. It relates to a method of manufacturing by plastic working in the atmosphere without reducing the quantity.

[Conventional technology]

B containing the above as essential component compositions: C: 0.02-0.25% Cr: 18.0-25.0% W: 13.0-17.0% B: 0.001-0.1% As a containing CO-based heat-resistant alloy, C: 0.02 to 0.25%, Cr: 18.0
~25.0%.

W: I3.0-17.0%, B
: Contains 0.001 to 0.1% as an essential component composition, furthermore, Mn+2.0% or less, Si:
1.5% or less.

Fe: 5.0% or less, AΩ: 1.0% or less.

Nl: 25.0% or less.

Contains one or more of these, and if necessary, Zr: 0.005 to 0.1%, Ca: 0.005 to
0.05%, rare earth metals: Contains 11!1 or 2 or more of 0.001 to 0.02%, and 1 or 2 or more of Mo, Nb, Ta, and Hf in a total of 5% or less. However, a Co-based heat-resistant alloy is known that has a composition (the above, weight %) consisting of di-Co and unavoidable impurities, and this Co-based heat-resistant alloy has excellent high-temperature strength and oxidation resistance,
It is also known that B contained in the Co-based heat-resistant alloy particularly contributes to improving high-temperature creep properties.

The following procedure was used to process this B-containing Co-based heat-resistant alloy into a wire rod.

First, B content having a desired component composition is produced by melting and casting in a normal vacuum induction melting furnace.

A base heat-resistant alloy ingot was forged into a billet at a temperature of 1250°C, and this billet was then heated at a temperature of 1250°C.
After holding at 00℃ for 30 minutes, water-cooling intermediate annealing, pickling,
Cold-drawn into a round bar and further heated to a temperature of 1180℃30
After holding for 1 hour, water-cooling intermediate annealing, pickling, and cold drawing are repeated two or more times to obtain a wire rod.Finally, after holding at a temperature of 1200°C for 1 hour, water-cooling intermediate annealing, pickling, and cold drawing are performed to obtain a thin wire rod. was manufacturing. That is, generally, in order to process a B-containing Co-based heat-resistant alloy, the blooming forging temperature, hot working temperature, and intermediate annealing temperature before cold drawing are 1180 to 1250°C.

[Problem to be solved by the invention]

However, for example, B:5 produced by melting and casting the above
0 ppa + content O-based heat-resistant alloy ingot, temperature:
A billet with a diameter of IO is produced by blooming at 1250°C, and the above billet is held at a temperature of 1180°C for 30 minutes, and then water-cooled intermediate annealing, pickling, and cold drawing are repeated two or more times, and finally When a wire rod with a diameter of 1.6 m + * was prepared by holding at a temperature of 71,200 °C for 1 hour, water-cooled intermediate annealing, pickling, and cold drawing, the B content of the wire rod with the above diameter of 1.6 + am was reduced to 2 ppm. B-containing ffi of the ingot:
A phenomenon occurred in which a CO-based heat-resistant alloy wire rod with a B content significantly lower than 50 ppi was produced. In other words, 48 ppm was produced during processing from ingot to wire rod.
This resulted in a significant decrease in content. Such a phenomenon has not been previously found in Co-based heat-resistant alloys.

This phenomenon is especially noticeable on the surface of Co-based heat-resistant alloys, so it appears especially when producing thin wire rods, thin plates, thin-walled tubes, etc. from B-containing Co-based heat-resistant alloy ingots. A problem has arisen in that Go-based heat-resistant alloy fine wires, thin plates, thin-walled tubes, etc., of varying amounts cannot be obtained, and that desired mechanical properties such as high-temperature creep properties cannot be obtained.

[Means to solve the problem]

Therefore, the present inventors conducted the following research in order to solve such problems.

first, C: 0.05%, Cr: 20.4%.

W: 14.8%, B: 50ppm
・Contains Mn:OJ 96. SI: 0.2%.

A170.2%, Nl: 9.5%.

Zr: 0.01%, Fe: 1.8%.

A B-containing Co-based heat-resistant alloy plate having a composition (hereinafter, ff! amount %) consisting of Co and unavoidable impurities, and a thickness of 25 mm was prepared. This B-containing Co
Temperature: 1000℃, 1050℃ of base heat-resistant alloy plate.

1100℃, 1150℃, 1200℃, 1250
℃ and 1300℃, respectively, in the air for 24 hours, and the amount of B in the inside of the B-containing Co-based heat-resistant alloy plate was determined as n1, and the amount of B was taken as the vertical axis, and the temperature was is plotted on the horizontal axis, expressed in a graph, and the results are shown in the first
Shown in the figure.

From the results in Figure 1, it can be seen that at temperatures higher than 1150°C, the amount of B decreases as the temperature increases;
It can be seen that the amount of B decreases to an almost negligible level below 0°C. This is because the change in Bm is deeply related to the thermal stability of the carbide, and under heat treatment conditions where the carbide is stable, B is mainly incorporated into the carbide as a constituent element, so the change in the amount of B is small. However, under heat treatment conditions at high temperatures where carbides form a solid solution, B diffuses to the outer surface at a relatively high rate, where it forms some oxides with external oxygen, and B is released outside the Co-based heat-resistant alloy plate. It is presumed that B will dissipate, and in the latter case, it is thought that B dissipates quickly due to the high temperature.

Therefore, the B content can be reduced by processing the B-containing Co-based heat-resistant alloy while holding the blooming temperature, hot working temperature, and intermediate annealing temperature at lower temperatures than conventional ones: 1000 to 1150°C. He gained the knowledge that he could defend against 1 hit.

This invention was made based on this knowledge, and includes C: 0.02 to 0.25% Cr: 18. A B-containing Co-based heat-resistant alloy ingot containing O ~ 25.0% W: 13.0 ~ 17.0% B: 0.001 ~ 0.1% as an essential component composition is forged into a billet or slab by blooming. After making a processed material such as, hot processing such as hot forging or hot rolling, repeating intermediate annealing, pickling, and cold processing to process small diameter wire rod, thin wall tube, or thin plate. However, in the method of final heat treatment if necessary, the B content is such that the above-mentioned bloom forging, hot working, intermediate annealing, and final heat treatment are performed at a temperature of 1000 to 1150°C.

This method is characterized by a plastic working method for base heat-resistant alloys.

The above B-containing Cod! For heat-resistant alloys, temperature: 115
At temperatures higher than 0° C., the stability of the carbide is poor, and B dissolved in the alloy matrix diffuses and escapes at a relatively high rate on the outer surface. Therefore, the heat treatment temperature associated with processing is 115
Although the temperature is preferably 0°C or lower, on the other hand, if the temperature is lower than 1000°C, sufficient softening for subsequent plastic working cannot be obtained, leading to cracking during processing.

Therefore, the heat treatment temperature and plastic working temperature of the B-containing Co-based heat-resistant alloy are preferably 1000 to 1150°C.

The reason why the essential components of the B-containing Co-based heat-resistant alloy of the present invention are limited as described above is as follows.

C strengthens the base of the alloy, and W and Cr.

It is an important element that forms highly thermally stable carbides with other carbide-forming elements, incorporates B into carbides, and prevents B from dissipating during heat treatment, but if its content is less than 0.02% by weight, On the other hand, if the content exceeds 0.25% by weight, the desired effect will not be obtained, and the content will deteriorate hot workability and impair high-temperature strength, which is not preferable.

Therefore, the C content in the B-containing Co-based heat-resistant alloy was set at 0.02 to 0.25% by weight.

Cr is important for improving high-temperature oxidation resistance and as a constituent element of carbides, but if its content is less than 18.0% by weight, sufficient effects cannot be obtained; on the other hand, if its content exceeds 25.0% by weight, Adding it is not preferable because it will actually deteriorate mechanical strength and workability. Therefore, the Cr content is 18
．． The content was set at 0 to 25.0% by weight.

W is useful for increasing high-temperature strength and is also important as a main constituent element of carbides, but when its content is 1.
If it is less than 3.0% by weight, a sufficient effect cannot be obtained;
If the content exceeds 7.0% by weight, cracks are likely to occur during hot and cold working, which is not preferable. therefore,
The W content was set at 13.0 to 17.0% by weight.

B is an element useful for maintaining high-temperature strength and ductility, but if its content is less than o,oiii%, the desired effect cannot be obtained, whereas if it is added in excess of o,1% by weight, This is not preferable because it impairs workability and weldability. Therefore, the B content was set at 0.001 to 0.1% by weight.

In addition, one or two of Mo, Nb, Ta and Hf
It is more effective to prevent B from escaping when the total amount of these elements is added in an amount of 5% by weight or less, but if the amount added exceeds 5% by weight, cracking occurs during processing, which is not preferable.

〔Example〕

Next, the present invention will be specifically explained based on examples.

Example 1 Melt and cast in a 20 kg induction heating vacuum melting furnace, C: 0.05%, Cr: 21.0
%.

W: 14.3%, B: 0
．． 0070%.

Ni: 9.0%, Mn: 0.
2%.

S1:0.1%, A1:0
．． 3%.

Fc: 1.5%, Zr: 0.
01%.

A B-containing Co-based heat-resistant alloy ingot having a composition (the above, weight %) consisting of Co and inevitable impurities was produced.

This B-containing Co-based heat-resistant alloy ingot was heated at a temperature of 2115
A billet with a diameter of 10 mm was produced by blooming at 0°C, and this billet was held at a temperature of 1120°C for 30 minutes, then hot rolled into a round bar with a diameter of 8.2 am, and this round bar was Temperature: 1120°C for 30 minutes. After holding for 30 minutes, the diameter was reduced to a round bar with a diameter of 4.2 mm by blunt-pickling and cold drawing. Further, the round bar with a diameter of 4.2 mm was further heated at a temperature of 1100°C.
After holding for 20 minutes, the process of dulling, pickling and cold drawing was repeated twice to obtain a wire rod with a diameter of 2.2 mm, and finally,
After holding at a temperature of 71150°C for 1 hour, water-cooled intermediate annealing, pickling, cold drawing, and diameter: 1. A thin wire material of Bmm was produced.

Diameter thus obtained: 1.6 m+s of B-containing C
When the B content of the O-based heat-resistant alloy thin wire material was measured, it was found that B
: 0.0070% weight. From this result, it can be seen that no deboronization phenomenon is observed in the process of processing an ingot into a fine wire rod.

Example 2 A hole with a diameter of 0.5 mm was punched in the center axis of the billet with a diameter of 101 produced in Example 1 to produce a B-containing Co-based heat-resistant alloy raw tube, and this raw tube was heated to a temperature of 1100°C. After heating and holding for 1 hour, it was drawn using a cold drawing machine to a thickness of 1. A thin-walled tube of hm was fabricated. When the B content of this thin-walled tube was measured, the B content was 0.0068% by weight.
Met.

This result shows that almost no deboronization phenomenon is observed during the rolling process of the tube.

Example 3 The ingot produced in Example 1 was heated to 1150°C.
Slabs with a thickness of 15 were produced by blooming.

This slab was hot rolled at a temperature of 1125°C to a thickness of 8
Make a plate with a thickness of 8 mm above, and heat the plate with a thickness of 8 mm at a temperature of +100.
After holding for 30 minutes at C, water-cooled intermediate annealing was carried out, followed by pickling.
The thin plate was cold-rolled to a thickness of 5 m + *, and the thin plate was held at a temperature of 1020°C for 20 minutes, then the dull-pickling process of cold rolling was repeated 6 times to finally obtain a thickness of 0. , 6 dragon thin plates were prepared and further subjected to a final heat treatment at a temperature of 1100°C for 20 minutes.

When the B content of the thus obtained thin plate with a thickness of 0.6 mm was measured, it was found that B: 0.00 (i9% by weight)
Met. From the above measurement results, it can be seen that there is almost no difference between the B content of the above ingot and the B content of the thin plate with a thickness of 0.6 m + s, and therefore, almost no B dissipation is observed during plastic working. .

〔Effect of the invention〕

According to this invention, weight: %, C: 0.02~0.25%, Cr: 18.0~
25.0%.

W: 13.0-17.0%, B: 0.0
01-0.1%.

B-containing CoM heat-resistant alloy containing B as an essential component
Since plastic working can be performed in the atmosphere without causing any damage, it is possible to produce materials such as thin wire rods, thin plates, and thin-walled tubes made of B-containing Co-based heat-resistant alloys with a target B content.
This method has excellent effects in manufacturing rope materials such as fine wire materials, thin plates, and thin-walled tubes, such as eliminating the occurrence of defective products due to deviations in the target value of B content.

[Brief explanation of drawings]

FIG. 1 is a graph showing the relationship between the atmospheric heat treatment temperature and the surface B content of a B-containing Co-based heat-resistant alloy.

Claims (1)

[Claims] (1) Obtained by melting and casting, weight % C: 0.02-0.25% Cr: 18.0-25.0% W: 13.0-17.0% B: 0.001 A B-containing Co-based heat-resistant alloy ingot containing ~0.1% as an essential component is forged into a processed material such as a billet or slab, and this processed material is subjected to hot forging, hot rolling, etc. After hot working, a small diameter wire rod, thin-walled tube or thin plate is processed by repeating intermediate annealing, pickling and cold working, and if necessary, a final heat treatment is performed. A method for plastic working of a B-containing Co-based heat-resistant alloy, characterized in that intermediate annealing and final heat treatment are performed at a temperature of 1000 to 1150°C.