JPS6250521B2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to an improved method of hot isostatic pressing (hereinafter referred to as HIP), and more specifically, it aims to shorten the working time when preheating the object to be processed prior to HIP processing, and to improve the yield. Achieving improvements and HIP from preheating
This article relates to an improved HIP process that increases the utilization rate of the series of steps leading up to treatment and increases productivity.

In recent years, the HIP process has been used for forming and densifying high-speed steel powder, superalloy powder, etc., and is being commercialized. In this case, how to increase the operating rate of the relatively expensive HIP equipment, or in other words, how to shorten the HIP cycle time will greatly contribute to cost reduction. In particular, as products have become larger in recent years, the HIP equipment itself has also tended to become larger, and the HIP cycle time is increasing. Various measures have been taken to improve the efficiency of the HIP device, such as improving the heating device, but there are limits to the improvement of the device itself, and the cost of the device becomes enormous.

Other most effective methods include performing cold compression molding to increase the density of the powder filled into capsules prior to HIP treatment, or preheating the object in an atmospheric pressure furnace. A combination of these has been adopted. By the way, the inventors of the present invention have conducted various studies on the HIP process, and after repeated trial and error, found that there is a significant difference in the time required to raise the temperature of the object to be processed under pressure and under atmospheric pressure. We found that there are differences. In other words, the time required to heat the center of the powdered material in a capsule to the required temperature is found to be significantly shorter under pressure than under atmospheric pressure for the following reasons: Ivy.

(a) Under pressure, the thermal conductivity from the furnace atmosphere to the object to be processed becomes extremely large. That is, heat is well transferred from the atmosphere to the object to be processed. for example,
High-pressure argon gas at 1000Kg/cm ² has a density several hundred times that of argon at atmospheric pressure, but on the other hand,
Since its viscosity is only about 1.1 to 3 times higher, intense convection occurs and the convective heat transfer coefficient becomes extremely large.

(b) At the early stage of the HIP cycle, the powder material becomes densified, resulting in a dramatic increase in the thermal conductivity of the powder material. That is, heat conduction inside the object to be processed is improved.

(c) The capsule contracts as densification progresses. Since the temperature increase time is inversely proportional to the square of the diameter of the object to be treated, this effect also shortens the temperature increase time.

Next, Figure 1 shows the temperature rise curve when a capsule with an outer diameter of 310 mm filled with high-speed steel powder is heated from 0°C at a furnace atmosphere temperature of 1000°C, and the vertical axis is the object to be processed. The temperature at the center and the horizontal axis indicate time, and the calculation was performed using the finite element method.

In the figure, #1 to #4 correspond to the following conditions.

#1: Equivalent to heating under atmospheric pressure #2: Considering only improvement in heat transfer under high pressure (1000Kg/cm ² ) #3: Considering improvement in thermal conductivity due to densification #4: Due to densification Taking into account the contraction of the capsule.As you can see from Figure 1, the center of the capsule is 950
The time required to reach °C (95% of the furnace atmosphere temperature) is 435 minutes for #1, 368 minutes for #2, 94 minutes for #3,
#4 took 79 minutes. As a result, when heating the powder filled in a capsule, the pressure is 4
It was found that the heating time was reduced to one to one-fifth, and in particular, it was found that the improvement in thermal conductivity due to the densification of #3 greatly contributed to the shortening of the heating time.

Next, FIG. 2 is a diagram showing the relationship between pressure and powder density when the same high-speed steel powder is used. The temperature of the furnace in this case is 1050℃, but even though the initial powder packing density before pressurization was 65%, the density of the powder was reduced to 90% with a pressure of only 200Kg/ ^cm2 .
It can be seen that the heat transfer rate has increased to 100%, making a sufficient contribution to improving heat conduction. By the way, as mentioned above, when trying to improve the thermal conductivity of the object to be processed, the method of increasing the packing density by cold compression is well known. 4000~5000
A pressure of Kg/ ^cm2 is required, and the compressed density at that time increases by only a few percent, so the effect on improving thermal conductivity is small considering the use of an expensive cold forming machine. be.

Furthermore, when powder is subjected to HIP processing, it is common to fill the powder into a capsule made of a material that is not permeable to gas, vacuum degas the inside, then seal the capsule and perform HIP processing. It is. In addition, in order to manufacture tool steel products etc. with complex shapes by the HIP method, metal powder material is filled into a molded capsule with a shape corresponding to the product shape, and the capsule is filled with pressure medium particles. It is already well known that the material is embedded in an outer capsule and subjected to the same vacuum degassing and preheating steps as described above, followed by HIP treatment.

In such a well-known and commonly used method, if the inside of the capsule is not sufficiently degassed, residual air or replacement gas such as _N2 , or gases generated from the metal powder material may cause the inside of the final product to leak. It is believed that this can lead to the formation of pores or structures that can be a practical problem, and it is important to carry out careful degassing work over a long period of time. Because heat conduction is reduced, the preheating process takes a long time, and there are many factors that seriously impede process efficiency. Japanese Patent Publication No. 51-18202 states that in order to provide effective heat conduction during the preheating process, the capsule is temporarily filled with an inert, low molecular weight gas such as helium or hydrogen after the degassing process, and the preheating time is After heating to the desired temperature, remove the gas.
A method for subjecting to HIP processing is disclosed. Even in this method, deaeration, gas replacement, and exhaust gas must be performed in sequence, and the process has not yet been simplified.

On the other hand, the inventors of the present invention have tried the HIP method on various materials to be treated, and after conducting detailed studies, they have found that, except for those with very strict composition regulations, the compositional fluctuations caused by residual gas are generally negligible. I came to the conclusion that this is the case. This fact is also clear from the following explanation.

Now, suppose that when powder is filled in air into a capsule having an internal volume V() and an opening made of a material that is not permeable to gas, the filling rate is β. Then, when the capsule is sealed with air remaining inside the capsule, the powder material of Vβ() and the powder material of V(1-β) are contained in the capsule.
This means that the air in () is trapped.
By the way, the main components in the air are O ₂ = 20.93%, N ₂ =
78.10%, Ar=0.9325%, the following amounts of O ₂ , N ₂ , and Ar exist in the air of V(1-β)( ) confined in the capsule.

O ₂ ...V(1-β)×32/22.4×0.2093 =0.299V(1-β) (g) _N2 ...V(1-β)×28/22.4×0.7810 =0.976V(1 -β) (g) Ar…V(1-β)×0.009325 =0.009325V(1-β) (l) Of this gas trapped in the capsule with the powder, O ₂ and N ₂ are: It is absorbed into the metal powder by heating during preheating.
If the true density of the metal powder is (g/), then the weight of the final product is Vβζ (g), so the increased amount of O ₂ and N ₂ that initially remained in the capsule is O ₂ increased by O ₂ in the air
The concentration is 0.299V(1-β)/Vβρ=0.299(1-β)
β)/βρ. On the other hand, the N ₂ concentration is 0.976(1-β)/βρ.

For example, if the true density of the metal is 8200g/
, assuming that the filling rate into the capsule is 65%, the increase in N ₂ concentration = 0.976 (1-0.65) / 0.65
×8200=6.41×10 ^-5 =64.1 ppm O ₂ 〃 =0.299(1-0.65)/0.65
×8200=1·96×10 ⁻⁵ = 1.96 ppm It is a well-known fact that an increase in N ₂ and O ₂ to this extent does not have any adverse effect on product quality. next,
A quantitative study will be conducted on Ar that may remain in the final product. As already mentioned, the amount of Ar initially trapped in the capsule was 0.009325V.
(1-β)(). HIP treatment temperature T
(〓), the pressure is P (atm), and the volume of Ar after HIP treatment is V (). Now seal the capsule.
300〓 (27℃), and if all the trapped Ar remains in the final product as a gas, the following formula holds: 1 (atm) x 0.009325V (1-β) ()/
300(〓)=P(atm)・v()/T(〓) Therefore, v=0.009325V(1-β)T/300P (l) On the other hand, since the volume of the sintered body is Vβ() , becomes.

Now, here β = 0.65, T = 1373 (℃), P =
1000 (atm), the porosity = 2.30 x 10 ^-5 = 0.0023%, and the density of the sintered body is 99.9977%, that is, it can be seen that the density is increased to a value that poses no problem in practical use.

According to the above explanation, even if the inside of the capsule is not degassed, if the powder is a material that absorbs N ₂ and O ₂ , such as an alloy, there will be almost no damage to the final product after HIP processing. I understand that. However, even with such an advantageous process, a major problem actually arises when a preheating step is attempted to improve product productivity. In other words, the moment a non-degassed powder-filled capsule is inserted into a preheating furnace to preheat it, the residual gas inside the capsule expands thermally and destroys the capsule. In order to prevent this phenomenon, it is common practice at present to evacuate the inside of the capsule to a vacuum. If vacuum degassing is performed in this way, problems arise such as the capsule shape becomes complicated, it is difficult to seal the degassing tube, and it takes a long time for vacuum degassing. In addition, with the already proposed method of directly charging a non-degassed sealed capsule into a HIP furnace, the temperature rise time in the HIP furnace becomes longer, resulting in a decrease in productivity due to an increase in HIP cycle time. This remained a major problem.

The method of the present invention has been developed as a result of intensive research in order to solve the various problems associated with the prior art as described above.
It was completed based on the technical knowledge mentioned above, and it aims to shorten the preheating time, and also allows you to move from preheating to HIP.
By using specific equipment to carry out a series of processes leading to treatment, and by organically combining and functioning those specified processes, we can extremely shorten the HIP cycle time and increase the operating rate of expensive HIP equipment. The purpose is to increase productivity, thereby significantly improving productivity.

That is, the feature of the present invention is that, in a method of preheating an object to be treated and then performing HIP treatment in a high temperature and high pressure gas atmosphere, a high temperature and high pressure furnace for HIP, a plurality of pressurized preheating furnaces, and a gas storage tank and are arranged in a mutually connected piping manner and processed according to the following steps.

(1) The workpiece charged into the high-temperature and high-pressure furnace for HIP
A step of preheating the object to be processed, which is placed in at least one pressurized preheating furnace, under a pressurized gas atmosphere while performing the HIP treatment.

(2) HIP for objects to be processed in a high-temperature, high-pressure furnace for HIP
When the processing is completed, the high-temperature, high-pressure gas in the high-temperature, high-pressure furnace for HIP is supplied to the other pressurized preheating furnace into which the object to be processed is newly charged, until the predetermined pressure is reached, and preheating in the preheating furnace is started. At the same time, after collecting the remaining gas into the gas storage tank, there is a step of taking out the object to be processed from the high-temperature, high-pressure furnace for HIP, and (3) after collecting the gas in the pressurized preheating furnace, which has completed preheating, into the gas storage tank. , the object to be processed is removed from the preheating furnace.
The process of transferring to a high-temperature, high-pressure furnace for HIP, filling the high-temperature, high-pressure furnace with gas from a gas storage tank to a predetermined pressure, and starting the HIP process.

Embodiments of the method of the present invention will be explained below with reference to FIG. FIG. 3 is a schematic diagram showing an example of an apparatus used to carry out the method of the present invention, which includes a high-temperature high-pressure furnace 1 for HIP, a plurality of pressurized preheating furnaces 2, 2', and a gas storage tank 3. However, compressor 4 and valve 5,
6, 7, 8, 9, etc., and are connected to each other by piping. In this diagram, now
In the high-temperature and high-pressure furnace 1 for HIP, the object to be processed 10 is, for example,
The treatment is performed under a pressure of 1000 Kg/cm ² and a temperature of 1100° C. In the pressurized preheating furnace 2, the object to be processed 11 is preheated to a temperature of 1100° C. under a pressure of 200 Kg/cm ² , for example. In the other preheating furnace 2', only the temperature is at atmospheric pressure.
The temperature is maintained at 1100°C, and the object to be processed 12 is not inserted, but is waiting outside the furnace.

When the predetermined processing in the high-temperature, high-pressure furnace 1 for HIP is completed, the object to be processed 12 is inserted into the preheating furnace 2', and the 1000
Kg/cm ² of high-pressure gas is introduced into the preheating furnace 2' without passing through the compressor 4 by opening valves 8 and 9 and using the pressure difference until the pressure in the preheating furnace 2' reaches 200 Kg/cm ² . It is closed, and pressurization and preheating of the object to be processed 12 is immediately started. In this case, the excess gas in the high-temperature, high-pressure furnace 1 for HIP is sent to the gas storage tank 3 via the compressor 4, and the HIP process ends when the pressure in the high-temperature, high-pressure furnace 1 for HIP reaches atmospheric pressure. The object to be processed 10 is taken out.

On the other hand, the gas in the preheating furnace 2, which has been pressurized and preheated, is sent to the gas storage tank 3 via the compressor 4, and the pressure in the preheating furnace 2 is reduced to atmospheric pressure.
is immediately transferred to the high-temperature, high-pressure furnace 1 for HIP, and then gas is fed and filled from the gas storage tank 3 into the high-temperature, high-pressure furnace 1 until a predetermined pressure is reached, and the HIP process is started again.
In this way, by alternately operating the plurality of pressurized preheating furnaces 2, 2..., the operating rate of the HIP high-temperature and high-pressure furnace 1 can be greatly increased, and the pressure for pressurized preheating can be easily adjusted. This reduces the cycle time of the HIP process, significantly increases production, and also helps save energy.

Normally, it takes more than 6 hours to heat the object from room temperature to a high temperature of nearly 1100℃ even when using a high-temperature electric furnace, but according to the method of the present invention, the object is heated under pressure. By doing so, the heating time can be shortened to about 2 hours for the reasons already mentioned. Further, the advantage of pressurized preheating, as will be explained in detail later, is that it makes it possible to omit the degassing operation of the object to be processed.

However, even in the case of the method of the present invention, the time required for preheating is still several times the HIP processing time, so in order to further increase the operation rate of HIP processing, preheating is performed in another preheating furnace in step (1). It is effective to do so. In this way, it is most desirable to arrange three or more pressurized preheating furnaces for one high-temperature, high-pressure furnace for HIP and to alternately set up an organic operation program. be.

It goes without saying that automating the above series of steps using a program control system is a more effective embodiment of the method of the present invention.

The object to be processed to which the method of the present invention is applied is usually a sealed capsule and a powder to be processed filled inside the capsule. The powder to be treated is, for example, metal powder such as Fe-based alloy, Ni-based alloy, titanium alloy, cobalt metal, etc.
Alternatively, some ceramics such as Si ₂ ON ₂ (silicon oxynitride) can be mentioned, especially
Fe-based alloys and Ni-based alloys are most suitable for carrying out the method of the present invention. Further, such metal powder may be prepared as an intermediate compact by being preformed by cold pressing or using a binder or the like.

The capsule used in the method of the present invention is made of a gas-impermeable material, and unlike conventional capsules, it does not necessarily need to be equipped with an exhaust pipe, and naturally there is no need to consider connecting it to a vacuum pump or the like. For example, it is sufficient if the structure has an opening and the opening can be easily sealed. Examples of the gas-impermeable material include metal, glass, and a composite material of metal and glass, and these are selected as appropriate depending on the type of object to be treated and the mode of molding.

A capsule made of the gas-impermeable material as described above is filled with a required amount of powder of the object to be processed, or a preformed intermediate body is loaded, and the surroundings are surrounded to form a capsule. Pressure medium particles made of silica, alumina soft glass powder, or a mixture thereof are filled into the gaps to position the intermediate compact.

The object to be processed is loaded into the capsule in the air or under a nitrogen gas atmosphere.After loading, the product must be degassed if strict composition specifications are required, and if not, the capsule must be degassed. sealed without any damage. However, when such a capsule is used as the inner capsule of a double capsule, sealing is not necessarily required.

In the case of a double capsule, the inner capsule is formed in a shape that corresponds to the shape of the final product and has an opening in a portion thereof. Through this opening, the metal powder is filled into the inner capsule at atmospheric pressure or under a nitrogen gas atmosphere, preferably while stirring or shaking. After filling, a lid with a nozzle is attached to the opening by welding, and this nozzle is further forged or clamped to allow gas to flow, but to prevent the metal powder and pressure medium particles described below from flowing. It is preferable to close the gap while leaving a narrow gap.

By doing so, when the inner capsule is embedded in the pressure medium particles, the pressure medium particles are prevented from entering and mixing with the capsule and having an adverse effect on the product, and also preventing leakage and overflow of the metal particles.

The outer capsule in which the inner capsule is housed is made of a gas-impermeable material and has an opening for receiving the inner capsule and the pressure medium particles, and the opening is suitably configured to be easily sealed. be done. For example, after storing the inner capsule and pressure medium particles, a lid is welded and sealed, or a lid with a nozzle is installed, and the gas inside is sucked and degassed with a vacuum pump through the nozzle, and the nozzle part is closed. Close and seal.

An appropriate amount of fine pressure medium particles such as silica or alumina are stored in the outer capsule, and the pressure medium particles fill the gap between the entire circumferential surface of the inner capsule buried inside and the inner wall of the outer capsule. Fill it without
Also performs positioning of the inner capsule.

The double-combined capsule filled with metal particles and pressure medium particles as described above is sealed as described above, with or without evacuating the inside, and inserted into a pressurized preheating furnace. It is preheated to a predetermined temperature under a pressurized gas atmosphere. The pressure of the atmospheric gas in this case differs depending on the preheating temperature, but especially in the case of a non-degassing method, when preheated to a temperature of about 1000℃, the pressure of the atmospheric gas is theoretically at least about 4.2Kg/cm ² , about At 100°C, the pressure is at least 4.6Kg/cm ² , and in the case of a degassing method, a lower pressure can be used. However, in any case, in order to achieve better heating efficiency, shorten the preheating time, and effectively carry out the method of the present invention, it is necessary to use at least 100 kg/cm ²
Preferably, a pressure of about 200 kg/cm ² is applied. That is, a powder 14 and gas are contained in a sealed capsule 13 as shown in FIG. 4, the temperature at the time of filling is 300㎓ (27℃), the pressure is 1Kg/cm ² , and the preheating temperature is 1373㎓, for example. (1100℃).

Assuming that the powder is sintered by heating and its volume does not change, the internal pressure of the capsule will be 1373(〓)/300(〓)≒4.6 (Kg/cm ² ) due to thermal expansion of the gas. This value itself is not that large, but for example, if the capsule inner diameter is 300
If the diameter is φmm, then 3.25 tons of pressure is applied to each of the upper and lower lids. For example, in the case of the top lid, if you look at the cross section, it is restrained only by (A) and (B), so 3.25 tons of stress ends up concentrated in this part, and the top lid is heated as shown by the dotted line in the figure. It swells and eventually breaks at parts (A) and (B). Pressure preheating in the method of the present invention is extremely effective in preventing such thermal expansion, but the pressure required at this time is only 4.6 kg/cm ² under the above conditions. However, if shortening of the preheating time is also taken into account, as mentioned above, preferably at least 100 Kg/cm ² , particularly preferably at least 200 Kg/cm ² seems to be appropriate.

When the method of the present invention is applied, it is possible to perform preheating and HIP treatment without deaerating the inside of the capsule, which is a great advantage of the method of the present invention.
In other words, there is air or replacement air inside the capsule.
Even if _N2 gas remains, pressurized preheating prevents the capsule from being destroyed due to expansion during heating, and when the powder inside reaches a high temperature, it absorbs the residual gas. Therefore, even if the pressure is reduced afterwards, for example, in order to insert it into a HIP device, the phenomenon that the capsule will no longer be destroyed by internal pressure will occur. In addition, if the powder is made of a material that does not absorb N ₂ and O ₂ , at one end of the inside of the capsule,
A similar effect can be obtained by inserting an N ₂ and O ₂ absorbent (eg, titanium powder, aluminum powder, etc.). However, the above explanation is
Although we are discussing the compaction of powder only, it is easy to infer that the present invention can also be applied to the compaction of a preformed powder using a secondary pressure medium, for example. It is about to be done.

Next, specific examples of the method of the present invention will be listed.

Example C=1.05%, Cr=4.09%, Mo=6.05%, W=
A high-speed steel powder produced by a nitrogen gas atomization method having a composition of 6.40%, V = 2.37%, Co = 5.03%, and the balance Fe was filled into a thin capsule made of mild steel with a diameter of 310 mm. The packing density of the powder at this time was 65%. Then, without evacuating the inside of this capsule, the top cover was welded with air remaining,
Enclosed.

3 pressurized preheating furnaces (hereinafter simply referred to as preheating furnaces) for one high-temperature, high-pressure furnace for HIP (hereinafter referred to as HIP furnace)
A simulation test in which the capsules were preheated and subjected to HIP treatment using an apparatus similar to that shown in FIG.

First, the above-mentioned sealed capsule was charged into a first preheating furnace that had been preheated to 1100℃, and 200Kg/cm ² of Ar was heated.
It was heated while pressurized with gas. After holding in this state for 2 hours (at this point, as a result of preliminary experiments, the temperature in the center of the powder-filled capsule has risen to more than 95% of the holding temperature of the preheating furnace),
The valve leading to the gas storage tank was immediately opened and the compressor was activated to reduce the pressure of the Ar gas, but the pressure reduction did not cause damage to the container. And this preheated capsule, this
Immediately charge the HIP furnace, which has been preheated to 1100℃, and pressurize Ar gas from the gas storage tank.
The first HIP treatment was performed at 800 atm and held for 30 minutes. During the HIP process, the first preheating furnace continues to be preheated at normal pressure and the temperature is maintained at 1100°C, and the second preheating furnace is connected to the first preheating furnace for about an hour. The same object to be processed is preheated under pressure with a time lag, and the third preheating furnace continues to preheat under pressure with a time lag of about one hour between the third preheating furnace and the second preheating furnace.

When the first HIP process is completed, the separately prepared object to be processed is inserted into the first preheating furnace which is preheated under normal pressure, and immediately the piping connecting the HIP furnace and the first preheating furnace is opened. The valve was opened, and Ar gas in the HIP furnace was introduced into the first preheating furnace using the pressure difference until the pressure inside the first preheating furnace reached 200 Kg/cm ² .

The remaining Ar gas in the HIP furnace was sent to the gas storage tank by a compressor, and when the HIP furnace reached atmospheric pressure, the HIP-treated object was taken out. At this time, the pressurized preheating in the second preheating furnace has been completely completed, and after transferring the Ar gas therein to the storage tank and returning the internal pressure of the furnace to atmospheric pressure, the preheated object to be processed is heated.
Transferred to HIP furnace. Ar gas was immediately injected into the HIP furnace from the gas storage tank, and the second HIP process began. After the first HIP process is completed, the second
It took about 30 minutes until the HIP process started. At the end of the second HIP process, the Ar gas in the HIP furnace was sent to the second preheating furnace that was being preheated under normal pressure, and since the preheating work in the third preheating furnace had been completed, preheating was started from there. After the treatment was completed, the object to be treated was transferred to the HIP furnace, and the same work cycle as described above was repeated one after another.

In this way, the HIP furnace was operated with a cycle time of 1 hour, which is a truly astonishing reduction compared to the conventional cycle time of 8 to 10 hours. .

When the structure of the high-speed steel sintered body thus produced was observed using a microscopic photograph, no defects such as residual pores or inclusions caused by reaction with residual gas were observed.
It exhibits a uniform, fine, and healthy structure that is characteristic of powder metallurgy products.

Next, a tool is manufactured from this material according to a prescribed process, and after being quenched at 1210℃ for 3 minutes, OQ (oil quenching), and tempered at 560℃ for 1.5 hours 3 times, the tool is attached to a tool with a mounting angle of 0. −15−6−6−15−
Intermittent cutting was performed with R0.4, tool overhang 34mm, depth of cut 1.5mm, feed rate 0.2mm, and workpiece material SNCM8 (H _R C32) (with 4 grooves). Fig. 5 shows the cutting performance results with a conventional melt-metal tool made of the same steel type.

In Fig. 5, the horizontal axis represents the number of impacts, and the vertical axis represents the maximum amount of wear on the flank surface of the tool.Curve A represents the tool obtained by the method of the present invention, and curve B represents the conventional melted material tool. are shown respectively. As is clear from the figure, the superiority of the tool manufactured by the method of the present invention is remarkable.

As detailed above, the method of the present invention significantly improves the preheating efficiency and significantly shortens the preheating time, regardless of the presence or absence of the in-capsule degassing step, and furthermore, the method of the present invention significantly improves the preheating efficiency and reduces the preheating time. Through combinations and functions, we are able to dramatically increase the operating rate of expensive HIP equipment and achieve high efficiency, and the resulting products are of a quality that is comparable to that of conventional equipment. This is an industrially very advantageous method, as it allows for the production of various products.

[Brief explanation of the drawing]

Figure 1 is a diagram showing the temporal change in the center temperature of the workpiece when heated in a preheating furnace, and Figure 2 is a diagram showing the relationship between atmospheric gas pressure and powder density when preheating high-speed steel powder. Fig. 3 is a schematic diagram showing an example of an apparatus used to carry out the method of the present invention, and Fig. 4 shows a diagram of a powder-filled capsule sealed without degassing and preheated without pressure. A schematic explanatory diagram showing the state of capsule expansion, FIG. 5 shows a tool manufactured using a metallurgical product obtained by the method of the present invention,
FIG. 4 is a diagram showing cutting performance with a conventional tool. 1... High temperature and high pressure furnace for HIP, 2, 2'... Pressure type preheating furnace, 3... Gas storage tank, 4... Compressor, 5, 6, 7, 8, 9... Valve, 10, 1
1, 12...Object to be processed, 13...Capsule, 14
...Powder to be processed.

Claims (1)

[Claims] 1. A method of preheating an object to be treated and then subjecting it to hot isostatic pressing in a high-temperature, high-pressure gas atmosphere,
Hot isostatic pressing is characterized in that a high-temperature, high-pressure furnace for hot isostatic pressing, a plurality of pressurized preheating furnaces, and a gas storage tank are arranged with pipes connected to each other, and processing is performed according to the following steps. Press method. (1) While hot isostatic pressing is being applied to the workpiece charged into the high-temperature and high-pressure furnace, at least one
(2) After the hot isostatic pressing process for the workpieces in the high-temperature, high-pressure furnace is completed, a new workpiece is placed in a pressurized preheating furnace. The high-temperature, high-pressure gas in the high-temperature, high-pressure furnace is supplied into the other pressurized preheating furnace in which the processing body is charged, until the preheating furnace reaches a predetermined pressure, and preheating in the preheating furnace is started, and the remaining gas is poured into the gas storage tank. After recovery, the process of taking out the object to be processed from the high-temperature high-pressure furnace; and (3) collecting the preheated gas in the pressurized preheating furnace into a gas storage tank, and then transferring the object to be processed from the preheating furnace to the high-temperature high-pressure furnace. and filling the high-temperature high-pressure furnace with gas from the gas storage tank to a predetermined pressure to start hot isostatic pressing. 2. The hot isostatic pressing method according to claim 1, wherein the object to be processed comprises a sealed capsule and powder to be processed filled inside the capsule. 3. The object to be processed comprises a sealed capsule, pressure medium particles filled inside the capsule, and a preformed powder compact embedded within the pressure medium particles. hot isostatic pressing method. 4. The object to be treated comprises a sealed outer capsule, pressure medium particles filled in the outer capsule, and an inner capsule embedded in the pressure medium particles and filled with the powder to be processed. The hot isostatic pressing method according to item 1. 5. The hot isostatic pressing method according to claim 2 or 3, wherein the capsule is sealed without deaerating the inside thereof. 6. The hot isostatic pressing method according to claim 4, wherein the outer capsule is sealed without evacuating the inside thereof. 7. The hot isostatic pressing method according to claim 2 or 3, wherein the capsule is sealed with the inside thereof deaerated. 8. The hot isostatic pressing method according to claim 4, wherein the inner capsule is sealed with the inside thereof deaerated. 9. The hot isostatic pressing method according to any one of claims 1 to 8, wherein during step (1), another pressurized preheating furnace is preheated at normal pressure.