JP7298941B2 - Manufacturing method of titanium sintered material - Google Patents

Description

The present invention relates to a method for producing a high-strength, high-toughness titanium sintered material.

Japanese Patent No. 3459342 (Patent Document 1) discloses a method of hydrogenating titanium or a titanium alloy by utilizing hydrogen embrittlement of titanium or a titanium alloy and then pulverizing it to an arbitrary particle size to obtain titanium hydride powder. A hydrodehydrogenation method is described in which this is dehydrogenated by vacuum heating and converted to titanium powder.

In the titanium-based powder, the oxygen content of the entire powder increases as the amount of fine powder having a small particle size increases. The reason for this is that, for example, hydrogenated fine powder having a particle size of 10 μm or less has a large specific surface area and takes in oxygen from the air due to processing heat during pulverization, resulting in a high oxygen concentration.

In the invention described in Japanese Patent No. 3459342 (Patent Document 1), by adjusting the powder ratio of fine powder having a particle size of 10 μm or less, the oxygen content in the titanium hydride powder is reduced to the allowable range of 0.15% by weight. are controlled below. Specifically, after pulverizing the titanium hydride powder, fine powder having a particle size of 10 μm or less is selectively removed from the resulting titanium hydride powder having a maximum particle size of substantially 150 μm or less, whereby the titanium hydride powder is pulverized. It is adjusted so that the proportion of powder having a particle size of 10 μm or less is 8% by weight or less.

Japanese Patent No. 3459342

As described in Patent Document 1, titanium hydride powder with a particle size of 10 μm or less is not used as an alloy raw material.

An object of the present invention is to provide a high-strength and high-toughness titanium sintered material while reducing production costs by actively utilizing titanium hydride powder with a particle size of 10 μm or less, which is usually discarded. be.

In one aspect, the method for producing a titanium sintered material according to the present invention comprises:
In this method, hydrogenated titanium hydride powder and titanium powder are mixed and sintered. This method is characterized in that the average particle size of the titanium hydride powder is 10 μm or less, the average particle size of the titanium powder is 20 μm or more, and the entire mixed powder of the titanium hydride powder and the titanium powder is , the amount of titanium hydride powder is blended so as to be 15% or more and 75% or less by weight.

In another aspect, a method for producing a titanium alloy sintered material according to the present invention comprises mixing a hydrogenated 64 titanium alloy powder having a composition of Ti-6Al-4V and being hydrotreated with titanium powder. It is a method of sintering. This method is characterized in that the average particle size of the hydrogenated 64 titanium alloy powder is 10 μm or less, the average particle size of the titanium powder is 20 μm or more, and the entire mixed powder of the hydrogenated 64 titanium alloy powder and the titanium powder is used. On the other hand, the amount of the hydrogenated 64 titanium alloy powder is blended so as to be 5% or more and 55% or less.

The above titanium powder is, for example, titanium powder that has been dehydrogenated after being hydrogenated. Alternatively, the titanium powder may be atomized titanium powder produced by an atomizing method.

In yet another aspect, a method for producing a titanium alloy sintered material according to the present invention comprises a hydrotreated hydrogenated 64 titanium alloy powder having a composition of Ti-6Al-4V and a hydrogenated titanium alloy powder having a composition of Ti-6Al- In this method, titanium alloy powder of 4V is mixed and sintered. This method is characterized in that the average particle size of the hydrogenated 64 titanium alloy powder is 10 μm or less, the average particle size of the titanium alloy powder is 20 μm or more, and the hydrogenated 64 titanium alloy powder and the titanium alloy powder are mixed. The content of the hydrogenated 64 titanium alloy powder is 15% or more and 75% or less with respect to the entire powder.

The above titanium alloy powder is, for example, a titanium alloy powder that is dehydrogenated after being hydrogenated. Alternatively, the titanium alloy powder may be an atomized titanium alloy powder produced by an atomizing method.

According to the above-described method of the present invention, titanium hydride powder or titanium hydride alloy powder having a particle size of 10 μm or less, which is usually discarded, can be used to reduce production costs while achieving high strength and high toughness. We can provide binding materials.

FIG. 2 is a diagram showing the particle size distribution of titanium hydride powder (powder A); FIG. 2 is a diagram showing the particle size distribution of hydrogenated/dehydrogenated titanium powder (powder B). FIG. 4 is a diagram showing the particle size distribution of hydrogenated/dehydrogenated titanium powder (powder C). FIG. 4 is a diagram showing the particle size distribution of hydrogenated/dehydrogenated titanium powder (powder D). It is a structure photograph of sample numbers 4, 6, 9, 10, 11, 12 and 13 after sintering (before hot plastic working). It is a structure photograph after sintering of sample number 13 and a structure photograph after hot plastic working. FIG. 2 shows a TiO ₂ -added mixed powder, (a) is a photograph of the appearance of the mixed powder, and (b) is an SEM image of the mixed powder. FIG. 2 is an SEM image showing the structure of TiO ₂ -added mixed powder after sintering. FIG. 10 is an SEM image of mixed powder of sample number 10. FIG. It is a figure which shows the particle size distribution of atomized powder. It is a structure photograph after sintering of sample number 9 and sample number 16. FIG. 4 is a diagram showing the particle size distribution of hydrogenated 64 titanium fine powder (powder E). FIG. 3 shows the particle size distribution of hydrogenated/dehydrogenated 64 titanium powder (powder F). It is a structure photograph after sintering (before hot plastic working) of sample numbers 22, 23, 24, 25, 26, 27, 28, and 29.

The inventors of the present invention conducted various experiments to find a method for producing a high-strength, high-toughness titanium sintered material using titanium hydride powder with a particle size of 10 μm or less. Experimental content, experimental results and considerations are described in detail below.

[Confirmation of sinterability]
A fine powder of titanium hydride having a particle size of 10 μm or less was compacted to produce a compact, and then the compact was sintered under vacuum. When the sintered body was examined, cracks were generated, and a good sintered body was not obtained. The reason why a good sintered body could not be obtained is thought to be that the titanium hydride fine powder having a particle size of 10 μm or less is too hard and difficult to obtain a high density.

For comparison, a hydrogenated/dehydrogenated titanium powder with a particle size of 10-45 μm was compacted to produce a green compact, which was then sintered under vacuum. No cracks were found in the sintered body, and it was confirmed that the sinterability was good.

In the above experiment, fine powder of titanium hydride and hydrogenated/dehydrogenated titanium powder were pressure-molded by a press to prepare a green compact, and the green compact was sintered. Similar results are expected to be obtained even if titanium powder is compacted by hot isostatic pressing (HIP) or cold isostatic pressing (CIP) and then sintered.

From the above experimental results, the following points were considered.

a) If the particle size of the powder is too fine, there is a concern that the sinterability will be impaired.

b) Therefore, it is difficult to produce a good sintered body only with titanium powder having a particle size of 10 μm or less.

c) Titanium hydride powder with a grain size of 10 μm or less is hard because it contains a lot of oxygen, and it is difficult to produce a high-density sintered body.

d) It is the density of the powder aggregate that affects sinterability. If the powder aggregate has a density of 95% or more, for example, the pores are closed and become independent pores. On the other hand, if the density is less than, for example, 95%, there will be open pores in addition to closed pores. If there are continuous pores, air enters during hot plastic working, and the nitrogen density in that portion increases.

e) In order to maintain good sinterability while reducing costs, a mixed powder of titanium hydride fine powder with a particle size of 10 μm or less and titanium powder with a particle size of 10 μm or more is prepared, molded and sintered. to do.

[Powder used in the experiment]
Powders shown in Table 1 below were prepared in order to prepare mixed powders.

The prepared powder A, powder B, powder C, and powder D are commercial products.

Powder A is a titanium hydride powder, the particle size distribution of which is shown in Table 2 below and in FIG.

The powder particles constituting Powder A (titanium hydride powder) contain 90% by weight or more of particles having a particle size of 10 μm or less. Its average particle size (median diameter) is 5.7 μm. Powder A is sometimes referred to as "TF" in the following tables and drawings.

Powder B is a hydrogenated/dehydrogenated titanium powder, the particle size distribution of which is shown in Table 3 below and in FIG.

Powder particles constituting powder B (hydrogenated/dehydrogenated titanium powder) contain 90% by weight or more of particles having a particle size in the range of 10 μm to 150 μm. The average particle size (median diameter) is 63.4 μm. Powder B may be referred to as "HDH" in the following tables and drawings.

Powder C is a hydrogenated/dehydrogenated titanium powder, the particle size distribution of which is shown in Table 4 below and in FIG.

The powder particles constituting the powder C (hydrogenated/dehydrogenated titanium powder) contain 85% by weight or more of particles having a particle size in the range of 10 µm to 45 µm. The average particle size (median diameter) is 28.7 μm.

Powder D is a hydrogenated/dehydrogenated titanium powder, the particle size distribution of which is shown in Table 5 below and in FIG.

The powder particles constituting the powder D (hydrogenated/dehydrogenated titanium powder) contain 85% by weight or more of particles having a particle size in the range of 45 μm or more and 150 μm or less. The average particle size is 80.2 μm.

[Production of sintered body]
Mixed powders were prepared by changing the ratio of powder A (TF: titanium hydride fine powder) and powder B (HDH: hydrogenated/dehydrogenated titanium powder), molded, and subjected to dehydrogenation heat treatment. Afterwards it was sintered under vacuum.

Specific manufacturing conditions were as follows.

Powder A (TF) and powder B (HDH) were prepared at the mixing ratio shown in Table 6, and the mixed powder after the mixing treatment was molded into a shape of φ41 × 30 mmH at a pressure of 710 MPa, and dehydrogenated at 600 ° C. After 7.2 ks of heating, a sintered body was obtained by vacuum holding under the conditions of 1000° C. for 10.8 ks.

[Measurement of Density, Hardness, Maximum Tensile Strength and Elongation of Sintered Body]
"Density (after sintering)" in Table 6 is the density of the sintered body obtained by the above manufacturing method.

The obtained sintered bodies (Sample Nos. 1 to 13 in Table 6) were cut into 20 mmt×30 mmt×40 mmL to prepare hot plastic working samples. Each sample was held at 850° C. for 1.8 ks in an air atmosphere, rolled from 20 mmt to 2.5 mmt (reduction rate: 87%), and then annealed. "Density (after hot plastic working)" in Table 2 is the density of the sintered body after hot plastic working.

For the obtained rolled sample, structural analysis by X-ray diffraction (Ultima IV: manufactured by Rigaku), structure observation by microscope (VHX-1000: manufactured by Keyence), SEM-EDX (JCM-6000EDS: manufactured by JEOL) Elemental analysis of the precipitated part was performed by

Regarding the mechanical properties, a tensile test (AUTOGRAPH AG-X: manufactured by Shimadzu Corporation) was performed at a strain rate of 5 × 10 ^-4 /s using a tensile test piece taken along the rolling direction. It was measured using a Vickers hardness tester (HMV-G: manufactured by Shimadzu Corporation). The density of each sample was evaluated by the Archimedes method.

The measured density, hardness, ultimate tensile strength (UTS) and elongation (ε) are shown in Table 6.

The following points can be read from the results shown in Table 6.

a) The higher the ratio of titanium hydride fine powder (powder A (TF)), the higher the oxygen content in the sintered body, and the higher the hardness and ultimate tensile strength. The reason for this is that the titanium hydride fine powder contains a large amount of oxygen, and thus serves as a supply source for oxygen solid solution strengthening. This is because the amount of dissolved oxygen increases.

b) With respect to the elongation value (ε), if the proportion of titanium hydride fine powder (TF) is 75% or less, the density of the sintered body before hot plastic working is 95% or more, and strength and elongation are improved. A proper balance is obtained. However, when the ratio is 77% or more, the density of the sintered body before hot plastic working becomes less than 95%, and the elongation value (ε) drops sharply. This is probably because it is difficult to increase the density of the sintered body to 95% or more when the ratio of titanium hydride fine powder is 75% or more, and continuous pores are formed in addition to independent pores. . If there are continuous pores, it is considered that air enters the continuous pores during hot plastic working, increasing the nitrogen concentration in that portion and causing a decrease in ductility. It can be seen that the nitrogen content of sample numbers 12 and 13 increases sharply. If the ratio of titanium hydride fine powder (TF) is 75% or less, the density of the sintered body before hot plastic working is 95% or more, and the pores are closed, leaving only independent pores. It is thought that

c) Focusing on the sintered material (sample number 1) consisting only of hydrogenated/dehydrogenated titanium powder (HDH), its oxygen content is 0.24% by weight, its hardness (HV) is 230, and its ultimate tensile strength is (UTS) is 524 MPa. In order to obtain a significant difference from the sintered material of sample No. 1 in terms of oxygen content, hardness and ultimate tensile strength, it is desirable to have a proportion of titanium hydride fine powder (TF) of 15% or more. Sample No. 4 with 15% titanium hydride powder has an oxygen content of 0.29% by weight, a hardness (HV) of 259 and an ultimate tensile strength (UTS) of 602 MPa.

d) When the ratio of fine titanium hydride (TF) is 77% or more, the elongation value (ε) drops sharply. It is desirable to

e) The sintered materials of sample numbers 4 to 11 with a titanium hydride fine powder (TF) ratio of 15% to 75% have a hardness (HV) of 250 or more and an ultimate tensile strength (UTS) of 580 MPa or more, The elongation (ε) is 18% or more.

[Results of structure observation]
FIG. 5 shows micrographs of sample numbers 4, 6, 9, 10, 11, 12 and 13 after sintering (before hot plastic working). Focusing on sample No. 12 with a ratio of titanium hydride fine powder (TF) of 77% and sample No. 13 with a ratio of 80%, it is observed that continuous pores appear. Continuous pores do not appear in Sample No. 4, Sample No. 6, Sample No. 9, Sample No. 10 and Sample No. 11 in which the ratio of titanium hydride fine powder (TF) is 75% or less.

FIG. 6 shows a photograph of the structure after sintering of sample number 13 and a photograph of the structure after hot plastic working. As is clear from the photograph of the structure after hot plastic working, sample No. 13 has a nitrogen-enriched portion.

[Influence of particle size of hydrogenated/dehydrogenated titanium powder]
The prepared hydrogenated/dehydrogenated titanium powders are Powder B, Powder C and Powder D (see Table 1). Powder B (HDH) has a particle size of 10-150 μm and an average particle size of 63.4 μm. Powder C has a particle size of 10-45 μm and an average particle size of 28.7 μm. Powder D has a particle size of 45-150 μm and an average particle size of 80.2 μm. It was investigated whether the difference in particle size distribution of the hydrogenated/dehydrogenated titanium powder mixed with the titanium hydride fine powder (TF) affects the properties of the finally obtained sintered material. The results are shown in Table 7 below.

Looking at the results in Table 7, no significant difference was observed in the oxygen content, density, hardness, maximum tensile strength and elongation, and it was recognized that equivalent properties were obtained. Therefore, preferably, the titanium powder to be mixed with the titanium hydride powder having a particle size of 10 μm or less (hydrogenated/dehydrogenated titanium powder in the present embodiment) has a particle size range of 10 μm or more and 150 μm or less and 90% by weight or more. with an average particle size of 20 μm or more. Moreover, it is desirable to mix the titanium hydride powder and the titanium powder so that the amount of the titanium hydride powder is 15% or more and 75% or less by weight based on the whole.

[Comparison with _TiO2 addition manufacturing method]
As a method for forming a solid solution of oxygen in a titanium material in order to improve the strength of the titanium material, a method of adding TiO ₂ powder to the titanium powder and sintering the mixed powder is known. A sintered body was made by the TiO ₂ addition process for comparison with the method of the present invention that utilizes titanium hydride fine powder.

The powders prepared are hydrogenated and dehydrogenated titanium powder (powder B: HDH) and TiO ₂ powder with a particle size of 10-150 μm. A mixed powder was obtained by mixing these two kinds of powders. The mixing ratio is 0.7% by weight of _TiO2 powder. The oxygen content of the entire mixed powder corresponds to 0.55% by weight, which is equivalent to sample No. 10 (66% powder A + 34% powder B) in Table 6.

If the _TiO2 powder is added into the titanium powder, the _TiO2 powder tends to agglomerate. FIG. 7(a) is a photograph showing the appearance of the mixed powder, and aggregation of the TiO ₂ powder can be seen in the portion surrounded by a circle. Fig. 7(b) is an SEM image of the mixed powder, in which the agglomeration of TiO ₂ can be clearly observed.

FIG. 8 is an SEM image showing the structure of the TiO ₂ -added mixed powder after sintering, in which an oxygen-enriched portion is observed, which may be attributed to insufficient mixing.

FIG. 9 is an SEM image of the mixed powder of sample number 10 (66% powder A+34% powder B). As can be seen from this figure, fine titanium hydride fine powder with a particle size of 10 μm or less is uniformly dispersed throughout.

The oxygen solid-solution strengthening method for titanium materials by adding TiO ₂ may cause problems such as aggregation of TiO ₂ and eventually scattering of oxygen-enriched parts when a large amount of TiO ₂ is added. On the other hand, the oxygen solid-solution strengthening method of titanium material using titanium hydride fine powder is advantageous in that it does not cause problems such as aggregation and scattered oxygen-enriched parts.

In order to adjust the oxygen content, based on the oxygen solid solution strengthening method of titanium material using titanium hydride fine powder, in addition to two types of powders, titanium hydride powder and titanium powder, TiO ₂ powder may be added to the extent that aggregation does not occur and they may be mixed.

[Use of atomized powder]
In the above-described embodiment, the titanium hydride fine powder and the hydrogenated/dehydrogenated titanium powder were prepared as starting materials for the mixed powder. Atomized powder can be used instead of the hydrogenated/dehydrogenated titanium powder.

A mixed powder (mixed ratio of 50:50), which was cold-formed, subjected to dehydrogenation heat treatment and then sintered under vacuum (Sample No. 16).

The titanium hydride powder prepared was Powder A listed in Table 1, containing more than 90% by weight in the particle size range of 10 µm or less, and having an average particle size of 5.7 µm. The prepared atomized powder was produced by a gas atomization method, and had an oxygen concentration of 0.10% by weight, a nitrogen concentration of 0.02% by weight, a hydrogen concentration of less than 0.01% by weight, and a carbon concentration of 0.01%. % by weight.

Table 8 and FIG. 10 show the particle size distribution of the atomized powder.

As shown in Table 8 and FIG. 10, 90% by weight or more of the powder particles constituting the atomized powder have a particle size range of 20 μm or more and 150 μm or less. The average particle size (median diameter) is 67.8 μm.

Table 9 below shows the strength properties of Sample No. 9 and Sample No. 16 after sintering and after hot plastic working.

As can be seen from Table 9, the sintered material (sample number 9) starting from a mixed powder of 50% titanium hydride powder (powder A) and 50% hydrogenated/dehydrogenated titanium powder (powder B) and the hydrogenated The sintered material (sample number 16) starting from a mixed powder of 50% titanium powder (powder A) and 50% atomized powder is equivalent in density, hardness, maximum tensile strength and elongation properties.

FIG. 11 is a micrograph of sample No. 9 and sample No. 16 after sintering. From these photographs, it can be recognized that both the sample No. 9 and the sample No. 16 have good structures with no continuous pores.

Even if the atomized powder is used instead of the hydrogenated/dehydrogenated titanium powder, it is possible to obtain a high-strength and high-toughness titanium sintered material while reducing the production cost by utilizing the fine powder of titanium hydride. can.

[Application to titanium alloy sintered materials]
From the viewpoint of providing a titanium sintered material with high strength and high toughness while reducing production costs by utilizing titanium hydride powder with a particle size of 10 μm or less, which is usually discarded, it is a pure titanium sintered material. No need to limit. For example, a titanium hydride powder with a grain size of 10 μm or less can be used as a starting material for the production of a titanium alloy sintered material such as Ti-6%Al-4%V. As titanium hydride powder, both pure titanium hydride powder and titanium alloy powder are conceivable.

A possible combination of starting materials for producing a sintered material of Ti-6%Al-4%V is, for example, the following pattern.

Pattern 1: Pure titanium hydride powder + Pure titanium powder + AlV alloy powder Pattern 2: Titanium hydride alloy powder (Ti-Al-V) + Titanium alloy powder (Ti-Al-V)
[Production of Titanium Alloy Sintered Material Containing Al and V]
Powders shown in Table 10 below were prepared as raw material powders for titanium alloy sintered materials containing aluminum (Al) and vanadium (V).

Powder E had the composition Ti-6Al-4V (64 titanium) and was hydrogenated. The particle size distribution of this hydrogenated titanium 64 fine powder is shown in Table 11 and FIG. 12 below.

The powder particles constituting Powder E (64 titanium hydride fine powder) contain 65% by weight or more in the particle size range of 10 μm or less. Its average particle size (median diameter) is 8.13 μm. In the following tables and drawings, Powder E may be referred to as "64TF".

Powder C (hydrogenated/dehydrogenated titanium powder) is the same as "powder C" described in Table 1, and is hydrogenated/dehydrogenated pure titanium powder. Its particle size distribution is as described in Table 4 and FIG. 85% by weight or more of the powder particles constituting the powder C have a particle size range of 10 μm or more and 45 μm or less, and the average particle size (median diameter) is 28.7 μm.

Powder F (hydrogenated/dehydrogenated 64 titanium powder) has a composition of Ti-6Al-4V and is a 64 titanium powder that has been hydrogenated and then dehydrogenated. The particle size distribution is shown in Table 12 below and in FIG.

Powder particles constituting powder F (hydrogenated/dehydrogenated 64 titanium powder) contain 60% by weight or more in a particle size range of 10 μm to 45 μm, and the average particle size (median diameter) is 39.49 μm.

[Preparation of Titanium Alloy Sintered Body Containing Al and V]
A mixed powder was prepared by changing the ratio of powder E (titanium hydride fine powder (64TF)) and powder C (hydrogenated/dehydrogenated pure titanium powder), molded, and dehydrogenated. Afterwards it was sintered under vacuum.

Specific manufacturing conditions were as follows. Powder E and powder C were prepared at the mixing ratio shown in Table 13, and the mixed powder after the mixing treatment was molded at a pressure of 710 MPa, dehydrogenated at 600 ° C. for 7.2 ks, and then heated at 1050 ° C. for 10 hours. A sintered body was obtained by holding the vacuum under the condition of 0.8 ks.

[Results of Observation of Structure of Titanium Alloy Sintered Body Containing Al and V]
FIG. 14 shows microstructure observation photographs (×500) of sample numbers 22 to 29 after sintering (before hot plastic working). Looking at the structure observation photograph of the sintered body of the mixed powder (sample number 29) containing 60% powder E (64TF) and 40% powder C (pure titanium), it can be seen that black continuous pores appear. Is recognized. Continuous pores do not appear in the structure observation photographs of the sintered bodies of sample numbers 22 to 28 with powder E contents of 5% to 55%.
[Measurement of Density, Hardness, Maximum Tensile Strength and Elongation of Titanium Alloy Sintered Body Containing Al and V]
"Density (after sintering)" in Table 13 is the density of the sintered body before hot plastic working. The obtained sintered bodies (Sample Nos. 21 to 29 in Table 13) were rolled from a plate thickness of 20 mmt to 2.4 mmt (reduction rate of 88%), and then annealed under the conditions of 750° C.×1.8 ks.

"Density (after hot plastic working)" in Table 13 is the density of the sintered body after hot plastic working.

A tensile test (AUTOGRAPH AG-X: Shimadzu Corporation) was performed using a tensile test piece sampled along the rolling direction. The hardness was measured using a Vickers hardness tester (HMV-G: Shimadzu Corporation). The density of each sample was evaluated by the Archimedes method.

The measured density, hardness (HV), ultimate tensile strength (UTS) and elongation (ε) are shown in Table 13. The following points can be read from the results shown in Table 13 and the structure observation results shown in FIG.

a) The higher the ratio of powder E (64 titanium hydride fine powder (64TF)), the higher the oxygen content in the sintered body and the higher the hardness and ultimate tensile strength. The reason for this is that the 64 titanium hydride fine powder contains a large amount of oxygen, so it serves as an oxygen supply source for strengthening the oxygen solid solution. This is because the amount of oxygen solid-soluted in is increased.

b) With respect to the elongation value (ε), if the ratio of the hydrogenated 64 titanium fine powder (64TF) is 55% or less, the density of the sintered body before hot plastic working is 95% or more, and the strength and elongation is properly balanced. However, when the ratio is 60% or more, the density before hot plastic working becomes less than 95%, and the elongation value (ε) drops sharply. This is probably because it is difficult to increase the density of the sintered body to 95% or more when the ratio of the 64 titanium hydride fine powder is 60% or more, and continuous pores are formed in addition to the independent pores. be Therefore, it is desirable to set the upper limit of the content of powder E (fine powder of 64 titanium hydride (64TF)) in the mixed powder to 55%.

c) Focusing on the sintered material (sample number 21) consisting only of hydrogenated/dehydrogenated pure titanium powder, its oxygen content is 0.24% by weight, its hardness (HV) is 230, and its maximum tensile strength ( UTS) is 524 MPa. In order to make a significant difference from sample No. 21 in terms of oxygen content, hardness and ultimate tensile strength, the lower limit of the content of powder E (64 titanium hydrogenation fine powder (64TF)) should be 5%. is desirable. According to the data posted on the website of Nippon Steel Corporation, Ti-3Al-2.5V has an oxygen content of 0.15 wt% or less, a strength of 620 MPa, and an elongation of 15%. Sample 22, which contains 5% powder E, has an oxygen content of 0.31 wt%, a strength of 628 MPa, and an elongation of 31.7%, which is superior to T-3Al-2.5V in mechanical properties.

d) The sintered materials of sample numbers 22 to 28 in which the ratio of powder E (64 titanium hydrogenated fine powder (64TF)) is 5% to 55% have a hardness (HV) of 276 or more and an ultimate tensile strength (UTS ) is 628 MPa or more, and the elongation (ε) is 14% or more.

[Comparison of structural observation results and mechanical properties of different grades]
Table 14 below compares the oxygen content and mechanical properties of materials of different grades. Sample No. 31 is a pure titanium material, Sample No. 32 is a 64 titanium alloy melt material, Sample No. 33 is a 64 titanium alloy powder sintered material, Sample No. 34 is a 32 titanium alloy melt material, and Sample No. 35 is a 32 titanium alloy powder sintered material. Sample No. 36-a is a mixed powder sintered material in which 0.6% TiO ₂ is added to 32 titanium alloy powder, Sample No. 36-b is a mixed powder in which 1.1% TiO ₂ is added to 32 titanium alloy powder Sintered material, sample number 36-c is a mixed powder sintered material in which 1.3% of TiO ₂ is added to 32 titanium alloy powder, sample number 37 is powder F described in Table 10 (hydrogenated / dehydrogenated 64 titanium A mixed powder sintered material in which 25% of powder E (64 titanium hydride fine powder (64TF)) was added to powder), and sample number 27 was a mixed powder sintered material containing 50% powder E and 50% powder C. and is the same as sample number 27 listed in Table 13.

Sample numbers 32, 33 and 37 are all 64 titanium alloy materials. It is recognized that the 64 titanium alloy powder material (sample number 33) is superior in mechanical properties (hardness and maximum tensile strength) to the 64 titanium alloy melt material (sample number 32). Sample No. 37 corresponds to one embodiment of the present invention, and is obtained by adding 25% of hydrogenated 64 titanium fine powder (64TF) to hydrogenated/dehydrogenated 64 titanium powder (powder F). The mechanical properties (hardness and ultimate tensile strength) of sample number 37 are superior to sample number 33 (64Ti alloy powder material). The elongation (ε) of sample number 37 is 7.2%, which is slightly inferior to the elongation value of sample number 33 (10%). Sample No. 37 contains 25% hydrogenated titanium 64 fine powder, which has been disposed of until now, so it is a low-cost material compared to Sample No. 33. Therefore, if the application does not require much elongation properties, the utility value of sample No. 37 is high.

The oxygen content of sample number 27 (50% powder E (64TF) + 50% powder C (pure titanium)) is 0.77%. The addition of _TiO2 is necessary to increase the oxygen content in the 32Ti alloy powder material. Sample No. 36-a to which 0.6% of TiO2 was added had an oxygen content of 0.54%, Sample No. 36-b to which 1.1% of TiO2 was added had an oxygen content of 0.74%, and 1.1% of TiO2 The oxygen content of sample No. 36-b with 3% addition is 0.80%. The elongation properties (ε) of Sample Nos. 36-b and 36-c with comparable oxygen content are much inferior to Sample No. 27, which corresponds to an embodiment of the invention. The reason for this is thought to be that a large amount of TiO ₂ added during powder mixing agglomerates and an oxygen-enriched portion is generated even after sintering. On the other hand, in sample No. 27 using 64 titanium hydrogenated fine powder, the problem of partial oxygen enrichment does not occur, and a large amount of oxygen can be uniformly solid-dissolved compared to the method of adding TiO ₂ . and can obtain better mechanical and elongation properties.

As described above, the larger the amount of the hydrogenated titanium hydride fine powder having an average particle size of 10 μm or less or the hydrogenated titanium 64 fine powder having an average particle size of 10 μm or less, the more the titanium sintered material. Alternatively, the amount of oxygen in the titanium alloy sintered material increases, and the hardness (HV) and ultimate tensile strength (UTS) increase. On the other hand, if the amount of titanium hydride fine powder and titanium 64 titanium hydride fine powder added is too large, the elongation value (ε) of the titanium sintered material or titanium alloy sintered material decreases. Among the applications of titanium sintered materials and titanium alloy sintered materials, there are applications that do not require much elongation properties. For example, in cutlery applications and wear resistance applications, strength (hardness and ultimate tensile strength) is considered more important than elongation properties. For such applications where strength is important, adding a large amount of fine powder of titanium hydride or fine powder of titanium 64 hydride makes it possible to increase the strength of the sintered material while reducing raw material costs. .

As a hydrogenated titanium powder used to increase the strength of the sintered material while reducing the raw material cost, not only pure titanium and 64 titanium, but also Ti-3Al-2.5V and Ti-3Al-3Mo-1V , Ti-4Al-3Mo-1V, Ti-4Al-4Mo-2Sn, Ti-5Al-2Cr-1Fe, Ti-5Al-1.5Fe-1.5Cr-1.5Mo, Ti-5Al-2Sn-2Zr-4Mo -4Cr, Ti-6Al-2Sn-2Zr-2Mo-2Cr, Ti-6Al-2Sn-4Zr-6Mo, Ti-6Al-2Sn-4Zr-2Mo, Ti-5Al-6Sn-2Zr-1Mo, Ti-6Al-2Cb -1Ta-1Mo, Ti-6Al-4V, Ti-6Al-6V-2Sn, Ti-7Al-4V, Ti-8Al-1Mo-1V, Ti-8Al-4Co, Ti-8Mn, and Ti-25Al-11Sn- Titanium-based fine powder such as 5Zr-1Mo can be used.

Although the embodiments of the present invention have been described above with reference to the drawings, the present invention is not limited to the embodiments described herein, and within the same or equivalent scope as the invention described in the claims, Various modifications are possible.

INDUSTRIAL APPLICABILITY The present invention can be advantageously used as a method for obtaining a high-strength and high-toughness titanium sintered material while reducing production costs. For example, since titanium hydride fine powder is usually discarded, the material purchase cost is equal to zero, and when 66% titanium hydride fine powder is mixed, the material cost is reduced to 1/3, which greatly contributes to the reduction of production costs. .

Claims (7)

A method for producing a titanium sintered material by mixing and sintering hydrogenated titanium hydride powder and titanium powder,
The titanium hydride powder has an average particle size of 10 μm or less,
The average particle size of the titanium powder is 20 μm or more,
The titanium hydride powder is blended so that the amount of the titanium hydride powder is 15% or more and 75% or less on a weight basis with respect to the entire mixed powder of the titanium hydride powder and the titanium powder. , a method for producing a titanium sintered material. A method for producing a titanium alloy sintered material by mixing and sintering hydrogenated 64 titanium alloy powder having a composition of Ti-6Al-4V and having been hydrotreated and titanium powder,
The hydrogenated 64 titanium alloy powder has an average particle size of 10 μm or less,
The average particle size of the titanium powder is 20 μm or more,
The amount of the hydrogenated 64 titanium alloy powder is blended so that the amount of the hydrogenated 64 titanium alloy powder is 5% or more and 55% or less with respect to the entire mixed powder of the hydrogenated 64 titanium alloy powder and the titanium powder. A method for producing a titanium alloy sintered material. 3. The method for producing a titanium sintered material according to claim 1, wherein the titanium powder is a titanium powder that has undergone a dehydrogenation treatment after a hydrogenation treatment. 3. The method for producing a sintered titanium material according to claim 1, wherein said titanium powder is atomized titanium powder produced by an atomizing method. Manufacture of a titanium alloy sintered material by mixing and sintering a hydrogenated 64 titanium alloy powder having a composition of Ti-6Al-4V and hydrotreated with a titanium alloy powder having a composition of Ti-6Al-4V a method,
The hydrogenated 64 titanium alloy powder has an average particle size of 10 μm or less,
The titanium alloy powder has an average particle size of 20 μm or more,
The hydrogenated 64 titanium alloy powder is blended so that the amount of the hydrogenated 64 titanium alloy powder is 15% or more and 75% or less with respect to the entire mixed powder of the hydrogenated 64 titanium alloy powder and the titanium alloy powder. , a method for producing a titanium alloy sintered material. 6. The method for producing a titanium alloy sintered material according to claim 5, wherein the titanium alloy powder is a titanium alloy powder that has undergone a dehydrogenation treatment after a hydrogenation treatment. 6. The method for producing a titanium alloy sintered material according to claim 5, wherein said titanium alloy powder is an atomized titanium alloy powder produced by an atomizing method.

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