JP3828651B2 - Molybdenum forged molded part and manufacturing method thereof - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
TECHNICAL FIELD The present invention relates to a molybdenum forged molded part such as a molybdenum container provided with a concave portion formed by forging and used at a high temperature, and a manufacturing method thereof.
[0002]
[Prior art]
A metal evaporation vessel using molybdenum, a metal oxide dissolution vessel, or a similar crystal production vessel, etc., should be regarded as a component of a set of production equipment used at high temperatures in the production process of various products. I can do it. As this component, a container having a concave portion is often used.
[0003]
This molybdenum container has the problem of short life as well as cost. Therefore, the operating life of various manufacturing apparatuses constructed using this container is short, and as a result, the amount equivalent to the running unit price in the cost of non-processed materials increases, which is a major obstacle to the manufacture of various products.
[0004]
Currently, for the life of this meaning, not are ones obtained to sufficiently satisfactory in the molybdenum container. In particular, the lack of deformation resistance at high temperatures at the bend, which is the boundary between the base defining the concave part of the molybdenum container and the closed side extending at a predetermined angle therefrom, is the biggest drawback and the biggest problem. There is also.
[0005]
Incidentally, the molybdenum container used in the production scale, generally phi 100 × 50 mm H or more larger sizes required, its practical life is important.
[0006]
In order to manufacture such an upper concave container made of molybdenum, the following manufacturing method can be considered. (I) Mori Bed solid wood seat scoop method den, and a method of narrowing the (ii) processed plate material.
[0007]
[Problems to be solved by the invention]
In the method (i), the core of the molybdenum sintered body material that is the material must be sufficiently sintered, and the furnace operating conditions must be different from those of other materials to be sintered. In addition, chips generated by cutting are wasted and the material is usually not subjected to processing such as rolling or forging, and its strength is insufficient.
[0008]
Further, although the method (ii) is generally used, it is necessary to take a relatively large thickness even after processing into a shape having a concave portion such as a final finished container. In this method, even if the spinning diaphragm and the turning diaphragm are made of molybdenum having a large deformation resistance of about 5 to 15 mm, the bent portion can be processed with high accuracy by hot working at 900 ° C. or more, preferably 950 to 1000 ° C. However, a reduction in the thickness of the side parts of the resulting molybdenum parts is inevitable, and the processing strain at the bent part, which is the boundary between the side part and the base part, is extremely large, and not only the fiber structure can be found but also at high temperatures. The strength variation is large, and stable use at high temperatures is difficult. However, this method is less wasteful in terms of material and is attractive in terms of cost.
[0009]
Further, among metal plastic working, press working is often used as permanent deformation. A warm temperature of about 400 to 600 ° C. is also generally used.
[0010]
However, although there is an example of cold working with a thin plate material for molybdenum, hot working is indispensable for the above-mentioned thickness and size, and it must be processed with a force that overcomes large deformation resistance. In addition, in order to form a molybdenum part having a concave portion with a press, it is necessary to compress a rough member and flow the material in the mold. However, the press die itself must fully consider the deterioration temperature of the die (for example, 650 ° C and practically 450 ° C is the limit for SKT4 materials), and the temperature drop during processing (thermal conductivity of molybdenum) Stainless steel is inevitable with a difference of 12 W / mK compared to 140 W / mK), and good processing cannot be performed.
[0011]
Therefore, the technical problem of the present invention is to provide a molybdenum forged molded part suitable for use at a high temperature and at a low cost, in particular, having a concave part with sufficient high-temperature deformation resistance at a bent part, and a method for manufacturing the same. It is in.
[0012]
[Means for Solving the Problems]
The present inventors have found that in the press, the pre-heating the mold to 400 to 450 ° C., it was heading to be able to satisfactorily process the molybdenum.
[0013]
According to the present invention, there is provided a method for producing a molybdenum forged molded part produced by forging a molybdenum sintered body having a theoretical density ratio of at least 94%, an oxygen content of 30 ppm or less, and a crystal grain size of 80 μm or less. Te, the molybdenum forging components is provided with a concave portion formed by the side portions together when extending through the bending portion from the base portion and the base portion, the rising angle of the sides defining said recess 85 degrees or less, the bending portion forms a boundary of the said base bottom portion is larger than R35mm, and the crystal grain size of definitive to the bent portion at 80μm or less, so that the average particle diameter is 15~40μm A method for producing a molybdenum forged molded part characterized by performing hammer hot die forging is obtained.
[0014]
Molybdenum itself should be 1000 ° C. or higher, preferably considering the cooling of handling, and considering that the forging process should be started immediately after heating to 1150 ° C. On the other hand, if the temperature exceeds at least 1250 ° C., recrystallization rapidly progresses, so it must be avoided. In order to prevent the heating temperature from being lowered during processing and to maintain the shape stability of the tip body after processing, the center of the female mold has a concave shape that does not hinder subsequent processing. It is also important to form a recess and easily place the molybdenum material in the center of the concave part to be formed.
[0016]
In other words, in the present invention, the shape of the mold can be inclined up to 85 degrees for the convex (male mold), and that of the concave (female mold) can be set to 7 to 10 degrees, so that the workability and detachment from the mold can be prevented. It was obtained that it was possible. In addition, when it is necessary to accurately set the rising portion to 90 degrees from the usage conditions, the shape is adjusted by cutting with a lathe or the like.
[0018]
Here, molybdenum forged parts produced by hammer forging can be processed at high speed, and there is also heat generated from the material itself during processing. It has the advantage of not requiring troublesome reheating.
[0019]
On the other hand, according to the present invention, a molybdenum sintered material used for manufacturing the molybdenum forged molded part, the molybdenum sintered material having a theoretical density of at least 94%, an oxygen content of 30 ppm or less, and a total carbon content. Is a molybdenum- molybdenum sintered material characterized by having a crystal grain size of 80 μm or less.
[0020]
That is, during hammer forging, in order to increase the strength of the bent part of the molybdenum part at high temperature, the size of the crystal grain of the bent part, preferably without bending (measured by photographic method) is 80 μm or less, and the average grain size is It is desirable that the material flow in which the range is about 15 to 40 μm and a stable structure is made possible. The presence of particles having a size of at least 80 μm increases the degree of cracking during processing, but greatly affects cracking at high temperatures.
[0021]
Naturally, the molybdenum material is sintered to the core, and if the theoretical density ratio is 93% or less, large cracks in the bent portion cannot be suppressed. In addition, large particles may be generated. In order to make the material flow smooth, the oxygen content in the sintered body is usually 40 to 80 ppm, but 30 ppm or less, the total carbon content is 10 ppm or less, and the crystal grain size is 80 μm or less. It was also found that good materials can be obtained. As for the production conditions, a sintered material meeting the object of the present invention can be obtained by paying attention to contamination of the raw material powder and holding at 1800 ° C. in hydrogen at a dew point of −20 degrees or less for 6 to 15 hours.
[0022]
In addition, according to the present invention, there is provided a method for manufacturing a molybdenum forged molded part, wherein the molybdenum forged molded part is manufactured by hammer die hot forging. According to the present invention, in the method for producing a molybdenum forged molded part, the method for producing a molybdenum forged molded part is characterized in that the die forging is performed with a processing energy of about 3 TONm to 12 TONm . According to the present invention, in the method for producing a molybdenum forged molded part, the method for producing a molybdenum forged molded part is characterized in that the die forging is forged by hammer hot die forging.
[0023]
In the forging method, the above-described hammer processing energy can be processed at about 6 to 12 TONm of molybdenum. Obviously, don't put too much power on small sizes. However, if this force is always applied during the machining process, not only will cracking occur, but the scale on the surface may peel off and scatter. At the end of processing, other materials are generally not strongly processed, but molybdenum should have the same considerations.
[0024]
In addition, as the mold release agent used in the present invention, for example, commercially available piercing oil 41 (commercially available product) may be used. Is good. In particular, the male is Once you have attached the Mori Breakfast Den, it is inconvenient not take off if Ne divided most of the case molybdenum. Thus, it was found that the hammer during processing was about 2 to 4 TONm while using a release agent, and it was preferable to set it to 1/3 of the subsequent processing conditions at the initial stage of processing. The reason why cracking and peeling can be prevented is that the hardened layer is reduced in temperature and softens the impact of the next hammer, and the familiarity with the mold works.
[0025]
According to the present invention, in the method for producing a molybdenum forged molded part, a molybdenum powder molding step for producing a molded body by hydrostatic pressing a metal molybdenum powder having an average particle size of 3 μm, and the molybdenum powder molded body has a dew point. Sintered molybdenum at 1800 ° C. for 6 to 15 hours in hydrogen of −20 ° C. or less, having a theoretical density ratio of at least 94%, an oxygen content of 30 ppm or less, a total carbon content of 10 ppm or less, and a crystal grain size of 80 μm or less. A sintering process for producing a body, a sintered body heating process for heating the molybdenum sintered body at 1150 ° C., and a mold preheating process for preheating a female mold for forging the molybdenum sintered body with a hammer die A release agent application step of applying piercing oil or delta forge as a release agent to the female mold, and the molybdenum sintered body on the female mold to which the release agent is applied And a forging process for forming a molybdenum forged part by forging with a processing energy of about 3 TONm to 12 TONm, and a method for producing a molybdenum forged molded part. It is done.
[0026]
Furthermore, in order to prevent cracking, peeling and double skin from occurring in the molybdenum forged parts, forging (generally referred to as roughing) to the plate up to about 1/3 of the total processing amount, then the above-mentioned mold if Susumere the by Ri processed forging, excellent high-temperature deformation strength of further bend, and molybdenum component dimensional accuracy with good concave portion after processing it was grasp possible.
[0027]
The overall degree of processing is generally preferably 60% or more, and if 80%, the effect is sufficient. In general, the surface of the forged product is often cut off by 1 to 1.5 mm. According to the method of the present invention, the surface of 0.2 to 0.4 mm, at most 0.5 mm, may be removed, and a double skin is formed. Even if it occurs, it is not necessary to cut beyond 0.6 mm. This is the effect of the above-mentioned method, and the economic effect is great when processing expensive molybdenum.
[0028]
Further, in the method of using molybdenum as a plate material by forging (generally T11 to 15 mm) and a molybdenum part having a concave portion by drawing, the overall material yield is often only about 40 to 60%, and expensive material is wasted. Is inevitable. However, according to the present invention, a yield of about 85% or more can be expected.
[0029]
Moreover, according to this invention, the molybdenum forge molded part manufactured by the manufacturing method of any one said molybdenum forged molded part is obtained. Moreover, according to this invention, the molybdenum container characterized by being manufactured from the said molybdenum forge molded part is obtained .
[0030]
In other words, if the width shape of the crystal to be collected is wide, the other length (dimensions other than depth and width) is rather small, and as a result, the molten metal volume is reduced and the thermal economy consumed is increased. In contrast, a rectangular container is desired. Neither the method of squeezing nor the method of sitting down is remarkably difficult with respect to the square shape, and there is no actual example for a rectangular tube container having a diameter corresponding to at least 100 mm in diameter × 50 mm in height and made of molybdenum alone. However, according to the present invention, it has been found that it can be easily manufactured once the amount of overhang of the material is grasped.
[0031]
The difference from the above-described cylindrical shape can be made in principle by changing the shape ratio of the workpiece in accordance with, for example, the ratio of width × length. For round materials, formation by hammer die forging is impossible. However, if it is quite large, it may be necessary to reheat in the middle or reapply the release material, so it is necessary to carefully observe the roughness of the skin.
[0032]
In the present invention, it can be said that the bent portion is a range in which R35 mm can be reasonably achieved. The material flow at the bend directly affects the structure. The larger the radius R of the bent portion, the more desirable the crystal structure produced by forging is left, which strictly affects the life. Therefore, it is necessary to pay attention to the protrusions such as burrs, crusts and foreign matters on the mold surface at the bent part of the mold.
[0033]
Furthermore, when the container obtained according to the present invention is used as a metal evaporation container or a metal oxide dissolution container, the deformation resistance of the bent portion at a high temperature is significantly higher than that of the conventional buckling or squeezing. It was confirmed to be excellent. The life until it becomes unusable is also excellent.
[0034]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described.
[0035]
(First embodiment)
FIG. 1 is a sectional view showing a molybdenum forged molded part according to the first embodiment of the present invention. As shown in FIG. 1, the molybdenum forged molded part according to the first embodiment is made of molybdenum having a base portion 1, a side portion 2, and a bent portion 3 that forms a boundary between the base portion 1 and the side portion 2. It consists of a concave container 10. In this concave container 10, the rising angle α of the side portion 2 from the base portion 1 is 45 degrees.
[0036]
Specifically, the concave container 10 shown in FIG. 1 is manufactured as follows.
[0037]
The raw material molybdenum oxide was reduced by a general method to obtain a metal molybdenum powder having an average particle diameter of about 3 μm. After forming by isostatic pressing and sintering at 1800 ° C for about 10 hours in hydrogen with a dew point of -26 degrees, a sintered body with a good appearance is obtained. The average grain size is about 18 µm and the maximum grain size The diameter was approximately 45 μm. Furthermore, the oxygen content is 22 ppm. The total carbon content was 5 ppm, and the theoretical density ratio was 95.4%. Further, the size was 13 kg, as planned, with a diameter of φ180 mm × height of H50 mm. This sintered body is heated to 1150 ° C. in a ceramic furnace in advance, and the piercing oil 41 is applied to the mold with a brush while it is dark, and the previous sintered body is set in a mold preheated to 420 ° C. from above. First, it was hit 3 times at 3.5 TONm and then 5 times at 11.8 TONm. Neither the mold nor molybdenum was reheated.
[0038]
The shape after processing is as shown in FIG. 1. The thickness of the base 1 is 18 mm, the opening is φ260 mm, the height is 55 mm, the double skin is hardly generated, and the cutting allowance with a slightly raised skin is about 0.3 mm. When this part was removed, a good appearance product was obtained. As a result of removing the so-called surplus part due to die forging, a workpiece of 11.2 kg was obtained. The material yield was 86%.
[0039]
When this container was used in a copper evaporation experiment in the range of 900 to 1200 ° C., the lifetime was about 2.5 times and 1.3 times that of those obtained by the conventional scooping and squeezing, respectively.
[0040]
(Second Embodiment)
A sintered body of 200 × 80 × H50 / 7.6 kg was obtained by the same processing as in the first embodiment. Applying Delta Forge 31 (Nippon Atchison Co., Ltd.) to a mold with a dark brush and setting the molybdenum heated to 1150 ° C. to a female mold, first tapping it at 3.0 TONm four times, then tapping it at 8.8 TONm eight times. Almost the desired B (width) 100 x L (length) 250 x H (height) It can be made into 55 shape, and finally it was 3.0 TONm. . The upper burr part was slightly cracked at the tip, but a good fabric appeared when the burr was cut. After the surface was acid cleaned, the top and bottom portions were finished to the desired shape accuracy by cutting. For use at a temperature higher than 1950 ° C., the life can be expected to be longer than that of a conventional cylindrical container.
[0041]
In addition, as a first comparative sample, in the sintered body manufacturing method similar to that of the first embodiment, the one having a crystal grain size of 90 to 100 μm is mixed due to a variation due to a management error of the sintering condition. The reason density ratio was 93.5%. Molybdenum and mold preheating and mold release material application were performed as prescribed, but a slight surface crack was generated by the second hammer, and the crack progressed as the number of hammers increased, so normal processing could not be maintained. It was. In addition, because the dew point and hydrogen conditions were not set as set, the sintered body with an oxygen content of 45 ppm and a total carbon content of 30 ppm had a slight crack at the center of the frame and moved to the outer peripheral position of the frame. Since the same crack was also generated inside, the cutting amount had to be made large at least, and the desired shape could not be obtained.
[0042]
Furthermore, as a second comparative sample, in the forging process according to the first embodiment, when the rise of the protruding side of the concave container was set to 88 degrees, the bent portion was greatly disturbed in the upper male mold. A malfunction occurred. In practice, it was not necessary to eliminate the cutting process, and it was confirmed that it was possible to make it possible up to 85 degrees.
[0043]
(Third embodiment)
FIG. 2 is a sectional view showing a molybdenum forged molded part according to a third embodiment of the present invention. As shown in FIG. 2, the molybdenum forged molded part according to the third embodiment is made of molybdenum having a base portion 5, a side portion 6, and a bent portion 7 that forms a boundary between the base portion 5 and the side portion 6. It consists of a concave container 20. In the concave container 20, the rising angle β of the side portion 6 from the base portion 5 is 85 degrees.
[0044]
Specifically, the concave container 20 shown in FIG. 2 is manufactured as follows.
[0045]
A sintered body ( 11.4 kg) having a diameter φ150 × height H60 was obtained by the same process as in the first embodiment. Molybdenum material and mold are preheated in the same manner as in the first embodiment, and the Delta Forge 31 (commercially available product from Japan Atchison) mold material is brushed three times at 2.5 to 3.5 T0 Nm from the top with a brush until dark. Then, after hitting 7 times with 8 to 11 TONm, hit 2 to 3 times with 3.5 TONm or less to finish. Neither the mold nor the molybdenum material was reheated. Shape after processing, are as shown in FIG. 2, the thickness of the base portion 5 T15mm, the height H at the opening phi 230 is 70 mm, the cutting allowance is observed slightly striped cracks in epidermis almost 0.5mm removed However, a product with a generally good appearance could be obtained for use. As with the first embodiment, after removing the burrs, the weight was 10.8 kg, and the material yield was 94%. When this container was used to dissolve metal oxides in an atmosphere of about 2000 ° C, the molten metal due to deformation and cracking at the bent part was significantly improved compared to the container obtained by the conventional method of drawing. The result is 1.4 times longer than the technology.
[0046]
In the method of forging in the same procedure, the first forging was upset forging, and after processing to T40 mm, heating was performed again and die forging was performed in the same manner as in Example 1. In this case, almost no cracks are found in the visual appearance, and in order to make the entire surface of the cut surface appear, it is good to remove approximately 0.2 mm and 0.3 mm depending on the part. Moreover, when the metal oxide was melted under the same conditions, it was improved over the die-forged product and the life was 1.8 times that of the drawn product, and the crystalline structure of the bent part before use was not lost, and the machining process However, it can be used freely according to the setting purpose because it can improve the dimensional accuracy.
[0047]
The thus obtained molybdenum-made concave container 20 according to the second embodiment of the present invention has a shape with excellent deformation resistance at a bent portion and high dimensional accuracy at a high temperature. .
[0048]
In the above-described embodiment, the concave containers 10 and 20 are optimal for crucibles, but are not limited to high temperatures such as metal evaporation containers, metal oxide dissolution containers, and crystal production containers used at high temperatures. It can be used for a part having a concave part in a part as used.
[0049]
【The invention's effect】
As described above, according to the present invention, a molybdenum forged molded part such as a molybdenum container having a concave portion that is suitable for use at a high temperature and is low in cost and particularly has a sufficient high-temperature deformation resistance at a bent portion, and its A manufacturing method.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing a molybdenum forged molded part according to a first embodiment of the present invention.
FIG. 2 is a sectional view showing a molybdenum forged molded part according to a third embodiment of the present invention.
[Explanation of symbols]
1,5 Base part 2,6 Side part 3,7 Bent part 10,20 Concave container

Claims (4)

Oxygen content 30ppm or less the theoretical density ratio of at least 94%, the crystal grain size to a method for producing the fabricated molybdenum forged part by forging molybdenum sintered body is 80μm or less, the molybdenum forging parts, when extending through the bending portion from the base portion and the base portion includes a concave portion formed by the side portions together, with the following rising edge of the angle of 85 degrees of said sides defining said concave portion, wherein section bends bounding the base and the bottom portion is larger than R35mm, and the crystal grain size of definitive to the bent portion at 80μm or less, an average particle diameter of the hammer heat between forging so that 15~40μm A method for producing a molybdenum forged molded part, characterized in that : The method for producing a molybdenum forged molded part according to claim 1 , wherein a molybdenum powder molding step of producing a molded body by hydrostatic pressing a metal molybdenum powder having an average particle diameter of 3 µm, and dew point of -20 degrees. A molybdenum sintered body having a theoretical density ratio of at least 94%, an oxygen content of 30 ppm or less, a total carbon content of 10 ppm or less, and a crystal grain size of 80 μm or less is produced by holding at 1800 ° C. in the following hydrogen for 6 to 15 hours. A sintering step for heating, a sintered body heating step for heating the molybdenum sintered body at 1150 ° C., a mold preheating step for preheating a female die for hammer die forging the molybdenum sintered body, A mold release agent coating step of applying a piercing oil or delta forge as a mold release agent to the female mold, and setting the molybdenum sintered body on the female mold coated with the mold release agent. A method for producing a molybdenum forged molded part, comprising: a hammer hot die forging step for die forging with a processing energy of about 3 TONm to 12 TONm to form the molybdenum forged molded part . A molybdenum forged molded part produced by the method for producing a molybdenum forged molded part according to claim 1 or 2 . A molybdenum container manufactured from the molybdenum forged molded part according to claim 3 .

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