WO2016047692A1 - Process for producing ru-containing corrosion-resistant titanium alloy - Google Patents
Process for producing ru-containing corrosion-resistant titanium alloy Download PDFInfo
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- WO2016047692A1 WO2016047692A1 PCT/JP2015/076943 JP2015076943W WO2016047692A1 WO 2016047692 A1 WO2016047692 A1 WO 2016047692A1 JP 2015076943 W JP2015076943 W JP 2015076943W WO 2016047692 A1 WO2016047692 A1 WO 2016047692A1
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C1/00—Making non-ferrous alloys
- C22C1/02—Making non-ferrous alloys by melting
- C22C1/03—Making non-ferrous alloys by melting using master alloys
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
- B22D21/00—Casting non-ferrous metals or metallic compounds so far as their metallurgical properties are of importance for the casting procedure; Selection of compositions therefor
- B22D21/02—Casting exceedingly oxidisable non-ferrous metals, e.g. in inert atmosphere
- B22D21/04—Casting aluminium or magnesium
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
- B22D23/00—Casting processes not provided for in groups B22D1/00 - B22D21/00
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C1/00—Making non-ferrous alloys
- C22C1/02—Making non-ferrous alloys by melting
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C14/00—Alloys based on titanium
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- the present invention relates to a method for producing a corrosion-resistant titanium alloy containing Ru, and in particular, is excellent in corrosion resistance (crevice corrosion resistance, acid resistance, etc.), and is less economical in corrosion starting from damage such as flaws and excellent in economic efficiency.
- the present invention relates to a method for producing a corrosion-resistant titanium alloy containing Ru.
- Titanium is actively used in the aircraft field and other fields because it is light and strong. In addition, since it has excellent corrosion resistance, it has been widely used for chemical industrial equipment materials, thermal / nuclear power generation equipment materials, seawater desalination equipment materials, and the like.
- Ti-0.15Pd alloy (ASTM Gr. 7) was developed.
- This titanium alloy utilizes the phenomenon that the contained Pd can reduce the hydrogen overvoltage and maintain the natural potential in the passive state region. That is, Pd eluted from this alloy due to corrosion is precipitated again and deposited on the surface of the alloy, whereby the hydrogen overvoltage of this alloy is lowered, the natural potential is maintained in the passive state, and excellent corrosion resistance is exhibited.
- ASTM Gr. Has excellent corrosion resistance. Since 7 contains Pd, which is a platinum group and is very expensive, its field of use has been limited.
- Patent Document 1 the most economical Ru among platinum group elements is used, and the Ru content is set to 0.001 to 0.15 mass%. Furthermore, by adding rare earth elements in combination, ASTM Gr. Titanium alloys having an excellent resistance to crevice corrosion with a small amount of platinum group compared to 7 have been proposed.
- Patent Document 1 it is possible to realize a corrosion-resistant titanium alloy that reduces the amount of platinum group and is excellent in economic efficiency.
- the stable production of a commercial large ingot is studied, the following problems are encountered. It has been found.
- platinum group element especially Ru, Ir, Os
- an alloy is produced by a melting method in which the maximum molten metal temperature is about 2000 ° C. or more like the VAR melting method, the specific gravity is large.
- the platinum group element may settle and segregate without completely dissolving.
- Patent Document 2 describes that “a compact (compact) in which sponge titanium or powdered titanium and a small amount of an additive element are blended is made, and a main component is formed around it. If the thin metal plate is wound alternately to create a cylindrical melted material and then drip melted, the additive melt yield of small amounts of alloying elements will be almost 100%, and the component distribution in the resulting ingot Is also stable and nearly uniform ”. Although this solution is effective, it is necessary to apply a foil strip that can be processed into a cylindrical shape for the thin plate to be used (for example, titanium, W, etc.). There was a problem.
- LDPE low density polyethylene
- Patent Document 4 discloses a method for melting and casting a titanium alloy containing Ru or Ir.
- a melting method capable of realizing a high temperature a mother alloy of Ti and Ru or Ti and Ir having a melting point lower than that of Ru or Ir alone is produced, and VAR (vacuum) capable of mass production using this mother alloy as a raw material.
- VAR vacuum
- the produced mother alloy is hard and pulverization is not easy. For this reason, in order to adjust a master alloy to a melt
- the present invention has been made in view of the problems of the prior art, and as disclosed in Patent Document 1, a platinum group element (Ru (85 USD / OZ INVESMTM TMINE 2013.5.26 6 which is most economical) In addition, by adding a rare earth element in combination with ASTM Gr. It is an object to economically provide a homogeneous titanium alloy ingot having an excellent resistance to crevice corrosion with a small amount of platinum group compared to 7.
- the present inventors investigated the problems that occur when Ru is added to Ti to make a large ingot, and are arranged as follows.
- Patent Document 2 In order to solve these problems, the application of the techniques of Patent Documents 2 to 4 was examined.
- Patent Document 2 it is essential to use a very expensive foil, which is difficult in terms of economy.
- Patent Document 3 In the method of Patent Document 3, the C content of the product ingot is increased and the strength is increased, but it is difficult to ensure ductility and workability as compared with the methods of Patent Documents 2 and 4.
- the present invention has been made in view of the above problems, and is a corrosion-resistant titanium alloy containing a high melting point platinum group element that suppresses contamination of the mother alloy and has a uniform segregation with little segregation on an industrial production scale. It aims at providing the manufacturing method of.
- the object is to provide a melting method suitable for the production of a corrosion-resistant titanium alloy that is excellent in economic efficiency and contains a high melting point platinum group Ru element.
- FIG. 1 shows a binary phase diagram of Ti-Ru (Springer Materials Landolt-Bernstein DATABASE). In the vicinity of 30 wt% of the Ru content, there is a region having a melting point lower by about 100 ° C. than the melting point of pure Ti.
- Patent Document 4 a mother alloy having this composition is prepared, and a granular mother alloy that has been subjected to sieving after pulverization is mixed with sponge titanium to form a compacted body, and the compacted body is melted in a plasma furnace. It is said that casting of homogeneous Ti-0.1Ru (ASTM Gr.26) corrosion-resistant titanium alloy ingot becomes possible.
- Patent Document 4 The inventors of the present invention have confirmed that the method disclosed in Patent Document 4 is a trial, and as a result, the obtained master alloy is hard, and unlike the “Brittles” described in the literature, it cannot be easily pulverized. Turned out to need to crash. Various studies have been made to reduce the cost of the crash and to prevent the contamination (such as Fe) from the crushed teeth in the crash process from causing the corrosion resistance deterioration, and the following (i) to (iv) Obtained knowledge.
- contamination such as Fe
- the upper limit of the rare earth element is such that the rare earth element content of the mother alloy is adjusted so that the total content of rare earth elements in the corrosion resistant titanium alloy obtained by using this mother alloy is 0.10% by mass or less. It is desirable. This is because the corrosion resistance of the obtained titanium alloy may be deteriorated when the rare earth element content exceeds 0.10% by mass in the obtained corrosion resistant titanium alloy.
- a titanium alloy ingot is produced in a large-scale furnace on an industrial production scale using this mother alloy as a raw material for the Ru source and rare earth element source, segregation of the high melting point Ru component is small, and contamination of Fe and the like mixed when the mother alloy is crushed Corrosion-resistant titanium alloy products can be obtained.
- the present invention has been completed based on the above-mentioned findings, and the gist of the following (1) to (3).
- the content of Ru is 10 to 40% by mass, and the content is 2 to 30% by mass and the rare earth element is 1/6 or more of the Ru content
- the content of the rare earth element in the master alloy is an amount adjusted so that the total content of the rare earth elements in the corrosion resistant titanium alloy is 0.10% by mass or less.
- the corrosion-resistant titanium alloy has an Ru composition of 0.01 to 0.15% by mass, a total of rare earth elements of 0.001% by mass or more, and the balance of Ti and inevitable impurities.
- the said corrosion-resistant titanium alloy is a manufacturing method of the corrosion-resistant titanium alloy containing Ru as described in said (1) whose Fe content which is an impurity element is 0.30 mass% or less.
- the segregation of Ru generated due to the high melting point of Ru is reduced and homogeneous.
- a corrosion-resistant titanium alloy ingot can be produced. Since the site of low Ru content does not occur because negative segregation can be reduced, the titanium product manufactured using the ingot obtained by the manufacturing method of the present invention has Ru, which is one of the elements that ensure corrosion resistance, uniformly. . For this reason, the problem that corrosion generate
- Patent Document 4 proposes a method for producing a corrosion-resistant titanium alloy with less Ru segregation using a pre-melted Ti—Ru-based mother alloy.
- the mother alloy is very hard and difficult to grind, jaw crusher
- FIG. 1 is a binary phase diagram of Ti—Ru.
- FIG. 2 is a graph showing the change in Ru content from the bottom of the VAR ingot to the top.
- FIG. 3 is a schematic view showing a test piece used in a heat-resistant (boiling) hydrochloric acid test, FIG. 3 (a) is a plan view, and FIG. 3 (b) is a side view.
- the present invention relates to a method for producing a corrosion-resistant titanium alloy containing Ru, a platinum group element, in which Ru has a content of 10 to 40% by mass, a content of 2 to 30% by mass and 1 / R of the Ru content.
- a mother alloy containing 6 or more rare earth elements and having a melting point of 2000 ° C. or less is melted and solidified, the solidified mother alloy is pulverized, and the crushed mother alloy and sponge titanium are mixed and dissolved.
- This is a method for producing a corrosion-resistant titanium alloy containing Ru that is melted in a furnace.
- % described below represents “mass%”.
- Alloy 1-1) Ru content in master alloy In order to melt a master alloy having a melting point of 2000 ° C. or less, the Ru content of the master alloy needs to be 10 to 40%. According to FIG. 1, the melting point of the binary alloy in this composition range is not only 2000 ° C. or lower, but also the melting point (1668 ° C.) of sponge titanium (pure titanium) blended in addition to the mother alloy when producing a corrosion-resistant titanium alloy. Low compared to Therefore, the Ru content is in the range of 10 to 40%.
- the reason why the lower limit is set to 10% is that if it is less than this, easy grindability necessary for the mother alloy cannot be secured even if rare earth elements described later are added.
- the upper limit is set to 40% because when it exceeds 40%, the melting point is rapidly increased and the uniformity of the mother alloy is impaired, and a large amount of contamination is generated during pulverization. Preferably, it is a region of 30 ⁇ 5% where the melting point is lowest.
- the rare earth elements are elements necessary for improving the grindability of the master alloy, and are dispersed in the alloy when the master alloy is dissolved.
- the solidified master alloy it exists as a compound of a rare earth element and Ru, and this compound enhances grindability.
- the corrosion-resistant titanium alloy contains a rare earth element, it is easily dissolved in a high-temperature, high-concentration chloride aqueous solution environment.
- Mm mixed rare earth metals
- the content of rare earth element in the mother alloy needs to be 2 to 30% in order to make the mother alloy easy to grind.
- the content of the rare earth element in the mother alloy is less than 2%, the content of the compound of the rare earth element and Ru is small, and the mother alloy is difficult to grind. As a result, a large amount of contamination is generated when the mother alloy is crushed.
- the content of rare earth elements in the master alloy exceeds 30%, a significant improvement in the grinding ability of the master alloy cannot be expected.
- a crushed mother alloy is used to produce a corrosion-resistant titanium alloy.
- the mother alloy contains a large amount of rare earth elements
- a large amount of rare earth elements is added as the Ru content increases in order to improve grindability. Will do. Since the corrosion resistant titanium alloy manufactured from the mother alloy containing a large amount of rare earth elements contains a large amount of rare earth elements, the hot workability becomes unsatisfactory at the stage of the product ingot, and the corrosion resistance also deteriorates.
- the rare earth element content in the mother alloy needs to be 1/6 or more of the Ru content.
- VAR melting is performed using an electrode in which a small ingot of sponge titanium and a mother alloy is pressed.
- the small master alloy used for this electrode is obtained by grinding, and the master alloy used for the product ingot needs to be excellent in grindability.
- the grindability is improved by the addition of the rare earth element, in order to obtain a sufficient effect, it is necessary to set it to 1/6 or more of the Ru content of the mother alloy.
- the rare earth element content in the mother alloy is preferably an amount adjusted so that the total rare earth element content of the corrosion-resistant titanium alloy as the final product is 0.10% or less.
- the rare earth element content of the corrosion resistant titanium alloy is 0.10% or less.
- the content of rare earth elements in it will be adjusted. Needless to say, the reduction rate of Ru and the rare earth element varies depending on the melting method, and also varies depending on the content in the mother alloy.
- rare earth elements have the effect of improving grindability, but if added too much, a low melting point rare earth compound is formed in the corrosion-resistant titanium alloy, so that hot workability is inferior at the product ingot stage. May be good.
- rare earth elements and titanium compounds may be deposited, resulting in poor corrosion resistance.
- the rare earth element content in the master alloy is preferably 4/3 or less of the Ru content, and more preferably 2/3 or less.
- the balance in the mother alloy is titanium and inevitable impurities described later.
- Melting point of master alloy 2000 ° C. or less
- VAR melting vacuum arc melting method
- EB melting electron beam melting method
- the former VAR melting method is suitable for low cost and mass production (10 ton / ingot or more).
- the maximum molten metal temperature is about 2000 ° C. and there is a problem that the raw material having a high melting point remains undissolved.
- the mother alloy mother alloy is melted and solidified.
- a mother alloy having such an alloy composition and melting point for example, commercially available sponge titanium, Ru chips, Mm raw materials, and the like are prepared.
- Each particle size varies depending on the production scale, but is generally 0.84mm to 12.7mm (Osaka Titanium S-95), 4mm square or less (Fruya Metal Ru irregular shot), 10mm square to 30mm square (Kusaka It is desirable to be used after cutting by Rare Metal Laboratory.
- each quantity which falls in the above-mentioned range is weighed and melted by arc melting or the like and solidified to obtain a mother alloy which is an ingot.
- the size of the mother alloy only needs to be large enough to enter the pulverizer, and may be about 30 mm square or less. It is desirable to repeat melting several times in order to homogenize the mother alloy.
- the mother alloy after solidification is pulverized.
- the mother alloy obtained as described above is pulverized so that a predetermined amount can be weighed as a Ru source and a rare earth element source.
- a commercially available joke crusher can be used for the pulverization.
- it is desirable to optimize the pulverization conditions such as the rotational speed of the pulverized teeth, the pulverization time, the pulverization atmosphere, and the tooth plate material in advance.
- the grain size of the mother alloy after pulverization may be a size that can be weighed as a Ru source and a rare earth element source, and is preferably about 2 mm square to 4 mm square, for example.
- the mother alloy after pulverization and sponge titanium are mixed and melted in a melting furnace.
- 4-1) Method for Producing Corrosion Resistant Titanium Alloy A predetermined amount of a pulverized mother alloy that is a Ru source and a rare earth element source and sponge titanium are weighed and mixed. The mixed raw material is compression-molded by a press machine to form a briquette having a predetermined shape. At that time, the titanium sponge used may be, for example, that used when producing a mother alloy.
- a cylindrical briquette is formed, welded to produce a consumable electrode, and the consumable electrode itself is melted by arc heat generated by flowing a large current between the bottom of the furnace.
- the melted metal has a temperature of about 2000 ° C. or higher.
- the molten metal is cast into a copper crucible and laminated and solidified to produce an ingot. It is preferable to repeat the melting of the ingot in the crucible several times (in the present invention, twice) for homogenization.
- Inevitable impurity elements in the corrosion-resistant titanium alloy produced by the production method of the present invention include Fe, O, C, H, N, and the like which enter from the raw material, the melted electrode and the environment, scrap, and the like Al, Cr, Zr, Nb, Si, Sn, Mn, Cu, and the like mixed in the case of using as a raw material.
- Fe etc. which are mixed from a grinding
- the corrosion-resistant titanium alloy as a product has Fe: 0.30% or less, O: 0.140% or less, C: 0.18% or less, H: 0.015% or less, N: 0 0.03% or less, Al: 0.3% or less, Cr: 0.2% or less, Mn: 0.01% or less, Cu: 0.1% or less may be contained, and in total It may contain 0.6% or less.
- Example 1 the characteristics of the mother alloy were investigated.
- Master alloy dissolution In order to investigate the characteristics of the master alloy used in the production method of the present invention, a master alloy having the composition shown in Table 1 was prepared.
- the jaw crusher was crushed under the following conditions using a SC-0605 type fine jaw crusher manufactured by Maekawa Kogyo Co., Ltd.
- ⁇ Device used Bruker's differential thermal analyzer ⁇ Measurement temperature: ⁇ 1700 °C ⁇ Atmosphere: Ar -Container material used: Yttria The upper limit of the measurement temperature is 1700 ° C. A material having a melting point exceeding 1700 ° C. is expressed as exceeding 1700 ° C.
- Ru Segregation Degree Segregation in the mother alloy Ru component causes a difference in grindability at each site in the grinding process. Therefore, the Ru content for each particle size of the mother alloy to be ground was analyzed, and the variation range of the analytical content was defined as the segregation degree.
- the particle size to be analyzed was JIS test sieve (1) on a 3.5 mesh sieve (2) 30-3.5 mesh (3) 200-30 mesh (4) 200 mesh sieve under 4 grain sizes.
- the highest Ru content ⁇ the lowest Ru content Ru segregation degree is defined.
- the jaw crusher used in this example grinds the object to be pulverized by mixing it with moving teeth and non-moving teeth.
- the component (Fe system) is mixed.
- the Fe content is analyzed chemically, and the difference between (Fe content in the particle size range with the highest Fe content)-(Fe content in the particle size range with the lowest Fe content) was defined as the amount of Fe contamination. This is because the amount of Fe mixed in the pulverization process is handled as contamination.
- the conventional example is an additional test of the example described in Patent Document 4.
- Table 1 shows the composition and property evaluation results of the prototype mother alloy.
- Example No. 1 Example No. The melting point of No. 1 was 1580 ° C. and 2000 ° C. or less, and Ru segregation was as small as 1% by mass or less. However, there is difficulty in pulverization, and the method defined in this example is as low as 50% or less. In addition, since it is difficult to grind, there is a large amount of Fe contamination mixed in from the ground teeth, and in the definition of this example, contamination of Fe exceeding 1% by mass was recognized.
- corrosion-resistant titanium alloys manufactured from a mother alloy containing a large amount of rare earth elements contain a large amount of rare earth elements, so that hot workability becomes unsatisfactory at the ingot stage of the product, and corrosion resistance also deteriorates. .
- Ru content ⁇ 10% by mass; 7 When the Ru content is less than 10% by mass, no improvement in grinding efficiency is observed even when rare earth elements are added. For this reason, the grinding efficiency is lowered and the amount of Fe contamination mixed exceeds 1% by mass.
- Example 1 the master alloy (Patent Document 4) of Example No. 1 listed in Table 1 and Example Nos. 3, 4, 5, 9, 10, and 11 within the scope of the present invention are compared and summarized.
- the amount of Fe contamination mixed from the pulverizer is 1 mass% or less in the scope of the present invention, whereas in Example No. 1, it reaches 3.8%.
- the grinding efficiency which is an index related to productivity, is 60% or more in the scope of the present invention after grinding for 10 minutes, but only 18% in Example No. 1, and is considered to be superior to the present invention. It is done.
- Example 2 the production method of the present invention was compared with the conventional production method.
- the superiority of the present invention was confirmed by comparing the corrosion resistance of the corrosion resistant titanium alloy obtained by the production method of the corrosion resistant titanium alloy of the present invention and the conventional production method.
- the conventional methods to be compared are a normal VAR dissolution method, a manufacturing method described in Patent Document 2, a manufacturing method described in Patent Document 3, and a method described in Patent Document 4.
- Table 2 shows the raw materials used in the present invention and members used for carrying out the conventional manufacturing method to be compared.
- Ti-0.03Ru-0.01Mm (mass%) was prototyped in 2P each by the method of the present invention and the conventional manufacturing method, and the degree of segregation and the corrosion resistance were investigated.
- Patent Document 3 Prepare two types of sponge titanium shown in Table 2 that are classified to 200 mesh (75 ⁇ m) or less and Ru powder that is classified to ⁇ 45 ⁇ m or less.
- LDPE low density polyethylene
- this pellet was compression-molded together with sponge titanium and massive Mm to produce a cylindrical compact (adjusted to have a composition of Ti-0.03Ru-0.01 Mm (mass%) 7 kg / p).
- Example No. 4 Example No. 4
- Example No. 9 Example No. 9
- this was compression-molded together with sponge titanium to form a cylindrical shape.
- a compact was obtained and used as a welding material for VAR melting (about 7 kg of primary electrode). This was welded and dissolved as a consumable electrode. Since the alloy components in the ingot are not sufficiently homogenized by only one melting, double melting is performed in which the first melting ingot is melted again as a consumable electrode. The obtained 21 kg ingot was used for the examples.
- Table 3 shows the dissolution conditions.
- Fe contamination considered to be caused by the pulverizer was recognized, and the Fe content was about 10 times that of the other methods.
- Fe is an element that degrades corrosion resistance. This influence of Fe is recognized in the corrosion resistance test results described later.
- Step 1; Hot forging Material ⁇ 140 mm ⁇ 250 mm length 890 ° C. heating; ⁇ 56 mm thickness ⁇ 140 mm width ⁇ 530 mm length 950 ° C. heating; ⁇ 33 mm thickness ⁇ 103 mm width ⁇ L (about 1160 mm) 2 heat Step 2; 850 ° C heating; ⁇ 4 mm thickness x about 110 mm width x L (1 heat) Step 3; annealing; 750 ° C x 30 minutes AC
- Patent Document 2 Patent Document 4
- Patent Document 4 it was possible to prototype a 4 mm thick plate material without the occurrence of cracks or the like. The material was very hard and cracked during hot forging, and the plate material could not be secured.
- Patent Document 3 is considered to be a material not suitable for actual production because of high C and O content and poor hot workability.
- FIG. 3 is a schematic diagram of a test piece for a heat-resistant (boiling) hydrochloric acid test
- FIG. 3 (a) is a plan view
- FIG. 3 (b) is a side view.
- the surface of this test piece 1 was polished with emery paper having a particle size of 600.
- the amount of corrosion (corrosion rate) per unit time was calculated from the mass decreased due to corrosion. Note that the sampling position of the test piece 1 is the top of the VAR secondary ingot. Part, Mid. Bot. The samples were collected from three places equivalent to each other and used in the test of the examples.
- the heat resistance (boiling) hydrochloric acid test is a corrosion test simulating the environment inside the crevice corrosion, and was performed under the following conditions.
- the boiling test vessel was equipped with a serpentine cooler, and the hot vapor was cooled back to liquid so that the solution concentration did not change.
- ingot Bot The corrosion rate of the part is Top. Bot. The tendency of the part to be excellent in corrosion resistance was recognized. As a result, as shown in FIG. This is thought to be due to the high Ru content of the part.
- the ingot Bot. From Top the same as the material obtained by the method of Patent Document 4, the ingot Bot. From Top. It is considered that the corrosion rate change over the part is small and the platinum group (Ru) is not segregated. Further, the corrosion rate is small compared to the material cast by the method of Patent Document 4, and the present invention 1 is ⁇ 2.5 mm / year in the initial 7 hours and ⁇ 0.2 mm / year in 96 hours in all parts. Invention 2 with even lower Fe content is ⁇ 2 mm / year for the initial 7 hours and ⁇ 0.1 mm / year for 96 hours.
- Table 6 summarizes the comparison of the dissolution production method of Example 2 from the above evaluation results.
- a titanium alloy containing the platinum group element Ru which is excellent in economic efficiency but has a high melting point and has been difficult to homogenize, is converted into the Ti—Ru— of the present invention.
- VAR melting which is an industrial manufacturing method suitable for mass production. Since the melting point of the mother alloy is 1700 ° C. or less, an alloy with an extremely small degree of segregation of the platinum group element Ru can be obtained. Therefore, according to the method for producing a corrosion-resistant titanium alloy of the present invention, it is possible to further improve the performance and reliability of equipment and equipment used in a corrosive environment (especially high temperature and high concentration chloride environment). is there.
- Such a titanium alloy can be obtained at a more economical raw material cost. For this reason, it is thought that it contributes to the expansion of application use of a corrosion-resistant titanium alloy.
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Abstract
Description
前記耐食チタン合金は、不純物元素であるFe含有量が0.30質量%以下である、上記(1)に記載のRuを含有する耐食チタン合金の製造方法。 (4)
The said corrosion-resistant titanium alloy is a manufacturing method of the corrosion-resistant titanium alloy containing Ru as described in said (1) whose Fe content which is an impurity element is 0.30 mass% or less.
1-1)母合金中のRuの含有量
融点が2000℃以下である母合金を溶製するためには、母合金のRu含有量は10~40%とする必要がある。図1によれば、本組成域における二元合金の融点は、2000℃以下のみならず、耐食チタン合金を製造する際に母合金以外に配合するスポンジチタン(純チタン)の融点(1668℃)と比較して低い。従ってRu含有量は10~40%の範囲とする。下限を10%としたのは、これ未満だと後述の希土類元素を添加しても母合金に必要な易粉砕性を確保出来ないためである。上限を40%としたのは、40%超えでは急激に高融点化して母合金の均一性が損なわれ、粉砕時にコンタミが多量に発生するためである。好ましくは最も融点が低くなる30±5%の領域である。 1) A mother having a Ru content of 10 to 40% by mass, a rare earth element having a content of 2 to 30% by mass and 1/6 or more of the Ru content, and a melting point of 2000 ° C. or less. Alloy 1-1) Ru content in master alloy In order to melt a master alloy having a melting point of 2000 ° C. or less, the Ru content of the master alloy needs to be 10 to 40%. According to FIG. 1, the melting point of the binary alloy in this composition range is not only 2000 ° C. or lower, but also the melting point (1668 ° C.) of sponge titanium (pure titanium) blended in addition to the mother alloy when producing a corrosion-resistant titanium alloy. Low compared to Therefore, the Ru content is in the range of 10 to 40%. The reason why the lower limit is set to 10% is that if it is less than this, easy grindability necessary for the mother alloy cannot be secured even if rare earth elements described later are added. The upper limit is set to 40% because when it exceeds 40%, the melting point is rapidly increased and the uniformity of the mother alloy is impaired, and a large amount of contamination is generated during pulverization. Preferably, it is a region of 30 ± 5% where the melting point is lowest.
希土類元素は母合金の粉砕性を高めるために必要な元素であり、母合金を溶解した際に合金中に分散して存在する。固化した母合金中では、希土類元素とRuとの化合物として存在し、この化合物が粉砕性を高める。また、耐食チタン合金が希土類元素を含有すると、高温、高濃度の塩化物水溶液環境で溶解しやすくなる。 1-2) Kinds of rare earth elements in the master alloy The rare earth elements are elements necessary for improving the grindability of the master alloy, and are dispersed in the alloy when the master alloy is dissolved. In the solidified master alloy, it exists as a compound of a rare earth element and Ru, and this compound enhances grindability. Further, when the corrosion-resistant titanium alloy contains a rare earth element, it is easily dissolved in a high-temperature, high-concentration chloride aqueous solution environment.
母合金の希土類元素含有量は、母合金を粉砕し易くするために2~30%である必要がある。母合金の希土類元素含有量が2%未満であると、希土類元素とRuとの化合物の含有量が少なく母合金が粉砕し難くなる。この結果、母合金を粉砕する際にコンタミが多量に発生してしまう。一方、母合金の希土類元素含有量が30%を超えて含有しても母合金の粉砕能力の大幅な向上は見込めない。また、耐食チタン合金を製造するには粉砕後の母合金を用いるが、母合金が多量の希土類元素を含有する場合、粉砕性を高めるため、Ru含有量の増加に伴い多量の希土類元素も添加することになる。希土類元素を多く含有する母合金から製造された耐食チタン合金は多量の希土類元素を含有するため、製品鋳塊の段階で熱間加工性が不芳になり、耐食性も悪化することになる。 1-3) Content of rare earth element in mother alloy The content of rare earth element in the mother alloy needs to be 2 to 30% in order to make the mother alloy easy to grind. When the content of the rare earth element in the mother alloy is less than 2%, the content of the compound of the rare earth element and Ru is small, and the mother alloy is difficult to grind. As a result, a large amount of contamination is generated when the mother alloy is crushed. On the other hand, even if the content of rare earth elements in the master alloy exceeds 30%, a significant improvement in the grinding ability of the master alloy cannot be expected. In addition, a crushed mother alloy is used to produce a corrosion-resistant titanium alloy. When the mother alloy contains a large amount of rare earth elements, a large amount of rare earth elements is added as the Ru content increases in order to improve grindability. Will do. Since the corrosion resistant titanium alloy manufactured from the mother alloy containing a large amount of rare earth elements contains a large amount of rare earth elements, the hot workability becomes unsatisfactory at the stage of the product ingot, and the corrosion resistance also deteriorates.
1-4)母合金の融点:2000℃以下 工業的に多量に純チタンあるいはチタン合金を製造する際の溶解手段は、VAR溶解(真空アーク溶解法)、EB溶解(電子ビーム溶解法)などがあるが、安価かつ大量生産(10ton/インゴット以上)に適するのは、前者のVAR溶解法である。VAR溶解法においては最高溶湯温度が2000℃強程度であり高融点の原料が溶け残る問題がある。この様な問題を解決するためには、VAR溶解法の融液温度とされる2000℃以下の融点の母合金を使用する必要がある。 The balance in the mother alloy is titanium and inevitable impurities described later.
1-4) Melting point of master alloy: 2000 ° C. or less As a melting means for producing a large amount of pure titanium or titanium alloy industrially, VAR melting (vacuum arc melting method), EB melting (electron beam melting method), etc. are used. However, the former VAR melting method is suitable for low cost and mass production (10 ton / ingot or more). In the VAR melting method, the maximum molten metal temperature is about 2000 ° C. and there is a problem that the raw material having a high melting point remains undissolved. In order to solve such a problem, it is necessary to use a mother alloy having a melting point of 2000 ° C. or less, which is the melt temperature of the VAR melting method.
このような合金組成および融点を有する母合金を製造するため、例えば市販のスポンジチタン、Ruチップ、Mmの原料等を準備する。各々の粒径は製造規模により異なるが、概ね、0.84mm~12.7mm(大阪チタニウム製 S-95)、4mm角以下(フルヤ金属製 Ru不定形ショット)、10mm角~30mm角(日下レアメタル研究所製 切断して使用)であることが望ましい。そして、前述の範囲に入るような量を各々秤量し、アーク溶解等により溶解して凝固することにより鋳塊である母合金を得る。母合金の大きさは、粉砕機に入る程度の大きさであればよく、約30mm角以下程度でよい。母合金の均質化を図るために、溶解を数回繰り返すことが望ましい。 2) The mother alloy mother alloy is melted and solidified.
In order to manufacture a mother alloy having such an alloy composition and melting point, for example, commercially available sponge titanium, Ru chips, Mm raw materials, and the like are prepared. Each particle size varies depending on the production scale, but is generally 0.84mm to 12.7mm (Osaka Titanium S-95), 4mm square or less (Fruya Metal Ru irregular shot), 10mm square to 30mm square (Kusaka It is desirable to be used after cutting by Rare Metal Laboratory. And each quantity which falls in the above-mentioned range is weighed and melted by arc melting or the like and solidified to obtain a mother alloy which is an ingot. The size of the mother alloy only needs to be large enough to enter the pulverizer, and may be about 30 mm square or less. It is desirable to repeat melting several times in order to homogenize the mother alloy.
耐食チタン合金の目標組成とするため、前述のように得られた母合金を、Ru源および希土類元素源として所定量秤量可能なように粉砕する。粉砕には例えば市販のジョーククラッシャーを用いることができる。ジョーククラッシャーに投入する母合金を効率よく粉砕するため、粉砕歯の回転数、粉砕時間、粉砕雰囲気、歯板材質などの粉砕条件を予め最適化しておくことが望ましい。粉砕後の母合金の粒径は、Ru源および希土類元素源として秤量可能な程度の大きさでよく、例えば2mm角~4mm角程度であることが望ましい。 3) The mother alloy after solidification is pulverized.
In order to obtain the target composition of the corrosion resistant titanium alloy, the mother alloy obtained as described above is pulverized so that a predetermined amount can be weighed as a Ru source and a rare earth element source. For example, a commercially available joke crusher can be used for the pulverization. In order to efficiently pulverize the mother alloy put into the joke crusher, it is desirable to optimize the pulverization conditions such as the rotational speed of the pulverized teeth, the pulverization time, the pulverization atmosphere, and the tooth plate material in advance. The grain size of the mother alloy after pulverization may be a size that can be weighed as a Ru source and a rare earth element source, and is preferably about 2 mm square to 4 mm square, for example.
4-1)耐食チタン合金の製造方法
Ru源および希土類元素源である粉砕した母合金と、スポンジチタンとを所定量秤量して混合する。混合した原料をプレス機で圧縮成形して所定の形状のブリケットを成形する。その際、使用するスポンジチタンとしては、例えば母合金を作製する際に用いたものでよい。 4) The mother alloy after pulverization and sponge titanium are mixed and melted in a melting furnace.
4-1) Method for Producing Corrosion Resistant Titanium Alloy A predetermined amount of a pulverized mother alloy that is a Ru source and a rare earth element source and sponge titanium are weighed and mixed. The mixed raw material is compression-molded by a press machine to form a briquette having a predetermined shape. At that time, the titanium sponge used may be, for example, that used when producing a mother alloy.
従来の耐食チタン合金の中で、白金族元素がRuの場合、すなわち、質量%で、Ru元素:0.01~0.15%、希土類元素:0.001%~0.10%、残部がTiおよび不可避な不純物からなる化学組成を有する耐食チタン合金を工業規模で製造する場合に、本製造方法が適する。特にRu含有量が少ない組成領域においては、負偏析が大きいと耐食性を担保するRu含有量の低い部分が発生し、腐食発生の起点となる可能性があるためである。 4-2) Reason for the present invention to be a production method suitable for melting a Ti—Ru alloy whose platinum group element is Ru Among conventional corrosion resistant titanium alloys, when the platinum group element is Ru, that is, by mass% In the case where a corrosion-resistant titanium alloy having a chemical composition consisting of Ru element: 0.01 to 0.15%, rare earth element: 0.001% to 0.10%, the balance being Ti and inevitable impurities is produced on an industrial scale. In addition, this production method is suitable. This is because, particularly in a composition region having a small Ru content, if negative segregation is large, a portion having a low Ru content that ensures corrosion resistance is generated, which may be a starting point of corrosion.
本発明の製造方法で製造した耐食チタン合金における不可避的不純物元素としては、原料、溶解電極および環境から侵入するFe,O,C,HおよびN等、およびスクラップ等を原料とする場合に混入するAl,Cr、Zr、Nb、Si、Sn、MnおよびCu等が挙げられる。また母合金を粉砕する際に粉砕歯から混入するFe等も挙げられる。これらの不純元素は、耐食性を低下させない範囲であれば混入しても問題ない。 4-3) Inevitable Impurity Elements Inevitable impurity elements in the corrosion-resistant titanium alloy produced by the production method of the present invention include Fe, O, C, H, N, and the like which enter from the raw material, the melted electrode and the environment, scrap, and the like Al, Cr, Zr, Nb, Si, Sn, Mn, Cu, and the like mixed in the case of using as a raw material. Moreover, Fe etc. which are mixed from a grinding | pulverization tooth | gear at the time of grind | pulverizing a mother alloy are also mentioned. These impure elements can be mixed as long as they do not lower the corrosion resistance.
1)母合金溶解
本発明製造方法に用いる母合金の特性を調査するために、表1に示す組成の母合金を調整した。 In Example 1, the characteristics of the mother alloy were investigated.
1) Master alloy dissolution In order to investigate the characteristics of the master alloy used in the production method of the present invention, a master alloy having the composition shown in Table 1 was prepared.
原料として市販の工業用純スポンジチタンJIS1、フルヤ金属製Ruチップ99.95%以上純度、日下レアメタル研究所製Mm(La=31.1%,Ce=55.1%,Nd=9.2,Pr=4.2%,Sm=0.3% 残;重希土類およびFe)、和光純薬工業の試薬 金属ランタン削り状(純度>99.5%)を使用した。 1-1) Raw materials Commercially available pure sponge titanium JIS1 as a raw material, Furuya Metal Ru chip 99.95% or higher purity, Kusaka Rare Metal Laboratory Mm (La = 31.1%, Ce = 55.1%, Nd = 9.2, Pr = 4.2%, Sm = 0.3% Residue; heavy rare earth and Fe), Wako Pure Chemical Industries, Ltd. Metal lanthanum shavings (purity> 99.5%) were used.
上記原料を表1に示す組成比に配合した約100gの原料を各々8P作成し、日本特殊機械製の水冷銅モールドに配置した原料を、非消耗電極アークを使い溶融しボタン型の鋳塊を得た。一度溶解が完了した鋳塊は、裏返しにして再溶解を行うことで均質化を図った。 1-2) Master alloy dissolution 8P each of about 100g of raw materials blended in the composition ratio shown in Table 1 was prepared, and the raw materials placed in a water-cooled copper mold made by Nippon Special Machinery were melted using a non-consumable electrode arc. A button-shaped ingot was obtained. Once the ingot was completely melted, it was turned upside down and remelted for homogenization.
上記溶解により得られたボタン鋳塊を市販のジョークラッシャーを用いて一定時間の粉砕を行った。粉砕により回収できた金属塊量を投入した母合金量で除算することで回収率とした。 1-3) Grinding efficiency The button ingot obtained by the above melting was pulverized for a certain time using a commercially available jaw crusher. The recovery rate was obtained by dividing the amount of metal mass recovered by pulverization by the amount of master alloy charged.
・回転数;300回転/分
・粉砕時間;10分
・雰囲気;酸化発火を防止するため上部よりArガスをフロー
・歯板材質;高マンガン鋳鉄 ・ Exit gap: 10mm
・ Rotation speed: 300 revolutions / minute ・ Crushing time: 10 minutes ・ Atmosphere: Ar gas flow from the top to prevent oxidative ignition ・ Tooth plate material: High manganese cast iron
粉砕効率=被粉砕材重量(クラッシャー底部で回収できた重量)/投入ボタン鋳塊総重量×100[%]
1-4)融点測定
チタン合金は活性であるため、チタンと反応性を有さない容器を準備し、Ar雰囲気にしたDTA(示差熱分析)装置を活用して融点を測定した。 Specifically, the grinding efficiency was calculated by the following formula.
Grinding efficiency = Weight of material to be crushed (weight recovered at the bottom of the crusher) / Total weight of ingot button ingot x 100 [%]
1-4) Melting point measurement Since the titanium alloy is active, a container having no reactivity with titanium was prepared, and the melting point was measured using a DTA (differential thermal analysis) apparatus in an Ar atmosphere.
・測定温度;~1700℃
・雰囲気;Ar
・使用容器材質;イットリア
測定温度の上限が1700℃である。1700℃を超える融点の材料は1700℃超えと表記する。 ・ Device used: Bruker's differential thermal analyzer ・ Measurement temperature: ~ 1700 ℃
・ Atmosphere: Ar
-Container material used: Yttria The upper limit of the measurement temperature is 1700 ° C. A material having a melting point exceeding 1700 ° C. is expressed as exceeding 1700 ° C.
母合金Ru成分に偏析があると、粉砕工程において部位ごとに粉砕性に差異が発生する。したがって、被粉砕母合金の粒度毎のRu含有量を分析し、分析含有量のバラツキ範囲を偏析度と定義した。 1-5) Ru Segregation Degree Segregation in the mother alloy Ru component causes a difference in grindability at each site in the grinding process. Therefore, the Ru content for each particle size of the mother alloy to be ground was analyzed, and the variation range of the analytical content was defined as the segregation degree.
(1)3.5メッシュ篩い上
(2)30-3.5メッシュ
(3)200-30 メッシュ
(4)200メッシュ篩い下
の4粒度とした。(1)~(4)の分析結果のうち、最も高いRu含有量-最も低いRu含有量=Ru偏析度と定義する。 The particle size to be analyzed was JIS test sieve (1) on a 3.5 mesh sieve (2) 30-3.5 mesh (3) 200-30 mesh (4) 200 mesh sieve under 4 grain sizes. Of the analysis results of (1) to (4), the highest Ru content−the lowest Ru content = Ru segregation degree is defined.
本実施例で用いるジョークラッシャーは、被粉砕物を動歯と不動歯に咬み混ませて粉砕を行うため、被粉砕物が硬い材料である場合は歯が摩耗して歯の構成成分(Fe系)が混入する。 1-6) Fe Contamination The jaw crusher used in this example grinds the object to be pulverized by mixing it with moving teeth and non-moving teeth. The component (Fe system) is mixed.
実施例番号No.1の融点は1580℃と2000℃以下でRu偏析は1質量%以下と小さかった。しかしながら粉砕に難があり、本実施例で定義した方法では50%以下と低い。また粉砕が困難なことから粉砕歯から入ると推測されるFeコンタミ混入量が多く、本実施例の定義では1質量%を超えるFeの混入が認められた。 1. Conventional example: Example No. 1
Example No. The melting point of No. 1 was 1580 ° C. and 2000 ° C. or less, and Ru segregation was as small as 1% by mass or less. However, there is difficulty in pulverization, and the method defined in this example is as low as 50% or less. In addition, since it is difficult to grind, there is a large amount of Fe contamination mixed in from the ground teeth, and in the definition of this example, contamination of Fe exceeding 1% by mass was recognized.
(希土類元素添加量)<(Ru含有量の1/6)では顕著な粉砕効率改善が認められず、本実施例で定義した方法では50%以下と低い。また粉砕が困難なことから粉砕歯から入ると推測されるFeコンタミ混入量が多く、本実施例の定義では1質量%を超えるFeの混入が認められた。従来例と比較して進歩性は認められない。 2. Rare earth addition range: Example No. 2
When (the amount of rare earth element added) <(1/6 of the Ru content), no significant improvement in grinding efficiency is observed, and the method defined in this example is as low as 50% or less. In addition, since it is difficult to grind, there is a large amount of Fe contamination mixed in from the ground teeth, and in the definition of this example, contamination of Fe exceeding 1% by mass was recognized. Inventive step is not recognized compared with the conventional example.
希土類元素の含有量が30質量%を超えても、母合金の粉砕能力の大幅な向上は見込めない。また、希土類元素を多く含有する母合金から製造された耐食チタン合金は多量の希土類元素を含有するため、製品鋳塊の段階で熱間加工性が不芳になり、耐食性も悪化することになる。 3. Rare earth element content> 30 mass%; 6
Even if the rare earth element content exceeds 30% by mass, a significant improvement in the grinding ability of the master alloy cannot be expected. In addition, corrosion-resistant titanium alloys manufactured from a mother alloy containing a large amount of rare earth elements contain a large amount of rare earth elements, so that hot workability becomes unsatisfactory at the ingot stage of the product, and corrosion resistance also deteriorates. .
Ruの含有量が10質量%未満になると希土類元素を添加しても粉砕効率改善が認められない。このため粉砕効率が低くなるとともにFeコンタミ混入量が1質量%を超えてしまう。 4). Ru content <10% by mass; 7
When the Ru content is less than 10% by mass, no improvement in grinding efficiency is observed even when rare earth elements are added. For this reason, the grinding efficiency is lowered and the amount of Fe contamination mixed exceeds 1% by mass.
Ru含有量が40質量%を超えると融点が急激に上昇してしまうため本発明本来の目的である低融点の母合金提供を実現出来ない。 5. Ru content> 40 mass%; 8
If the Ru content exceeds 40% by mass, the melting point rapidly increases, and thus it is impossible to provide a low melting point mother alloy that is the original object of the present invention.
本発明範囲においては、融点が2000℃以下と低く本実施例で定義した粉砕効率が50%を超え、Ru偏析が小さく、粉砕に起因するFeコンタミ混入が少ない母合金が提供できる。 6). The scope of the present invention; Example Nos. 3-5 and 9-11
Within the scope of the present invention, it is possible to provide a mother alloy having a melting point as low as 2000 ° C. or less, the grinding efficiency defined in this example exceeding 50%, Ru segregation being small, and Fe contamination due to grinding being small.
本発明の耐食チタン合金の製造方法と従来製造方法で得られる耐食チタン合金の耐食性を比較し、本発明の優位性の確認を行った。 In Example 2, the production method of the present invention was compared with the conventional production method.
The superiority of the present invention was confirmed by comparing the corrosion resistance of the corrosion resistant titanium alloy obtained by the production method of the corrosion resistant titanium alloy of the present invention and the conventional production method.
・一般的VAR溶解方法
表2に示すスポンジチタンを合金原料(Ru粉末、塊状Mm等)とともにプレス成形して約7kgのブリケットとし,3本準備した。これを溶接して消耗電極として溶解した。一回の溶解だけでは鋳塊の合金成分均質化が不十分なため,初回溶解の鋳塊を消耗電極として再度溶解する二重溶解とした。得られた21kgの鋳塊を実施例に供した。表3に溶解条件を示す。 2-1) Prototype method of materials used in the examples-General VAR melting method Titanium sponge shown in Table 2 is press-molded together with alloy raw materials (Ru powder, lump Mm, etc.) to form a briquette of about 7 kg, and three are prepared did. This was welded and dissolved as a consumable electrode. Since the alloy components in the ingot are not sufficiently homogenized by only one melting, double melting is performed in which the first melting ingot is melted again as a consumable electrode. The obtained 21 kg ingot was used for the examples. Table 3 shows the dissolution conditions.
表2に示すスポンジチタンのうち0.5インチ~200メッシュ(75μm)に分級したものと、Ru粉末のうち-45μm以下に分級したものとを鋳塊全体では目標組成となるように配合し、これを塊状Mmとともに圧縮成形して円柱状のコンパクトを得、その後純チタン箔(100μm厚)を巻き付けてVAR溶解用の溶接素材(約7kgの1次電極)とした。この溶接素材を溶接して消耗電極として溶解した。一回の溶解だけでは鋳塊の合金成分均質化が不十分なため,初回溶解の鋳塊を消耗電極として再度溶解する二重溶解とした。得られた21kgの鋳塊を実施例に供した。表3に溶解条件を示す。 -The method of Patent Document 2;
The titanium sponge shown in Table 2 classified into 0.5 inch to 200 mesh (75 μm) and the Ru powder classified into −45 μm or less were blended so as to achieve the target composition in the entire ingot, This was compression-molded together with the bulk Mm to obtain a cylindrical compact, and then a pure titanium foil (100 μm thickness) was wound around to form a welding material for VAR melting (about 7 kg primary electrode). This welding material was welded and dissolved as a consumable electrode. Since the alloy components in the ingot are not sufficiently homogenized by only one melting, double melting is performed in which the first melting ingot is melted again as a consumable electrode. The obtained 21 kg ingot was used for the examples. Table 3 shows the dissolution conditions.
表2に示すスポンジチタンのうち200メッシュ(75μm)以下に分級したものと、Ru粉末のうち-45μm以下に分級したものとを準備し、LDPE(低密度ポリエチレン)をバインダとして、重量比でTi;Ru;LDPE=6:3:1で十分に混合し、その後島津製作所製KBr錠剤成形機(φ13mm)を使い約1g/pのペレット成型体を作製した。 ・ Method of Patent Document 3 Prepare two types of sponge titanium shown in Table 2 that are classified to 200 mesh (75 μm) or less and Ru powder that is classified to −45 μm or less. LDPE (low density polyethylene) is used as a binder. As a weight ratio, Ti: Ru; LDPE = 6: 3: 1 was sufficiently mixed, and then a pellet molded body of about 1 g / p was produced using a KBr tablet molding machine (φ13 mm) manufactured by Shimadzu Corporation.
実施例1の実施例番号1の母合金(粉砕後)を使い、これをスポンジチタンおよび塊状Mmとともに圧縮成形して円柱状のコンパクトを得、VAR溶解用の溶接素材(約7kgの1次電極)とした。これを溶接して消耗電極として溶解した。一回の溶解だけでは鋳塊の合金成分均質化が不十分なため,初回溶解の鋳塊を消耗電極として再度溶解する二重溶解とした。得られた21kgの鋳塊を実施例に供した。表3に溶解条件を示す。 -Method of Patent Document 4 Using the master alloy of Example No. 1 of Example 1 (after pulverization), this is compression-molded together with sponge titanium and massive Mm to obtain a cylindrical compact, and a welding material for VAR melting ( About 7 kg primary electrode). This was welded and dissolved as a consumable electrode. Since the alloy components in the ingot are not sufficiently homogenized by only one melting, double melting is performed in which the first melting ingot is melted again as a consumable electrode. The obtained 21 kg ingot was used for the examples. Table 3 shows the dissolution conditions.
実施例1の実施例番号4(本発明1)、実施例番号9(本発明2)の母合金(粉砕後)を使い、これをスポンジチタンとともに圧縮成形して円柱状のコンパクトを得、VAR溶解用の溶接素材(約7kgの1次電極)とした。これを溶接して消耗電極として溶解した。一回の溶解だけでは鋳塊の合金成分均質化が不十分なため,初回溶解の鋳塊を消耗電極として再度溶解する二重溶解とした。得られた21kgの鋳塊を実施例に供した。表3に溶解条件を示す。 -Method of the present invention Using the mother alloy (after pulverization) of Example No. 4 (Invention 1) and Example No. 9 (Invention 2) of Example 1, this was compression-molded together with sponge titanium to form a cylindrical shape. A compact was obtained and used as a welding material for VAR melting (about 7 kg of primary electrode). This was welded and dissolved as a consumable electrode. Since the alloy components in the ingot are not sufficiently homogenized by only one melting, double melting is performed in which the first melting ingot is melted again as a consumable electrode. The obtained 21 kg ingot was used for the examples. Table 3 shows the dissolution conditions.
得られたVAR2次溶解2本のうち、1本について、縦に2分割して鋳塊中央部の底部から上部にかけてのRuの濃度を調査した。分析方法は、融合結合プラズマ質量分析法である。調査結果を図2に示す。 2-2) High melting point Ru segregation investigation One of the two VAR secondary melts obtained was divided into two vertically and the concentration of Ru from the bottom to the top of the center of the ingot was investigated. The analysis method is fusion coupled plasma mass spectrometry. The survey results are shown in FIG.
上記試作材の成分分析結果を表4に示す。 2-3) Components of prototype material Table 4 shows the results of component analysis of the prototype material.
実施例の材料の耐食性を評価するために、以下の工程で4mm厚の板材を試作した。 2-4) Prototyping of plate material In order to evaluate the corrosion resistance of the material of the example, a plate material having a thickness of 4 mm was manufactured in the following steps.
素材=φ140mm×250mm長
890℃加熱;→56mm厚×140mm幅×530mm長
950℃加熱;→33mm厚×103mm幅×L(約1160mm)2ヒート
工程2;熱間圧延;
850℃加熱;→4mm厚×約110mm幅×L(1ヒート)
工程3;焼鈍;
750℃×30分 AC
一般的なVAR溶解法、特許文献2,特許文献4,本発明の4つの実施例は、割れ等の発生無く、4mm厚の厚板材の試作が可能であったが、特許文献3に示された材料は非常に硬質で、熱間鍛造の際に割れが生じ、板材を確保することが出来なかった。 Step 1; Hot forging Material = φ140 mm × 250 mm length 890 ° C. heating; → 56 mm thickness × 140 mm width × 530 mm length 950 ° C. heating; → 33 mm thickness × 103 mm width × L (about 1160 mm) 2 heat Step 2;
850 ° C heating; → 4 mm thickness x about 110 mm width x L (1 heat)
Step 3; annealing;
750 ° C x 30 minutes AC
In the four examples of the general VAR melting method, Patent Document 2, Patent Document 4, and the present invention, it was possible to prototype a 4 mm thick plate material without the occurrence of cracks or the like. The material was very hard and cracked during hot forging, and the plate material could not be secured.
本発明のチタン合金製造方法で得られる材料の耐(沸騰)塩酸性を確認するため、以下の試験を実施して、その結果を評価した。 2-5) Corrosion resistance In order to confirm the (boiling) hydrochloric acid resistance of the material obtained by the titanium alloy production method of the present invention, the following tests were conducted and the results were evaluated.
図3は、耐熱(沸騰)塩酸性試験用試験片の模式図であり、図3(a)は平面図、図3(b)は側面図である。同図に示す、厚さ2mm、直径15mmのコイン状の試験片1を板材から切り出した。この試験片1は、表面を粒度600番のエメリー紙で研磨した。試験片1を下記条件で熱塩酸に浸漬した後、腐食により減少した質量から単位時間当たりの腐食量(腐食速度)を算出した。なお試験片1の採取位置はVAR2次鋳塊のTop.部、Mid.部、Bot.部に相等する3ヵ所から採取し、実施例試験に用いた。 Heat-resistant (boiling) hydrochloric acid test FIG. 3 is a schematic diagram of a test piece for a heat-resistant (boiling) hydrochloric acid test, FIG. 3 (a) is a plan view, and FIG. 3 (b) is a side view. A coin-shaped test piece 1 having a thickness of 2 mm and a diameter of 15 mm shown in FIG. The surface of this test piece 1 was polished with emery paper having a particle size of 600. After the test piece 1 was immersed in hot hydrochloric acid under the following conditions, the amount of corrosion (corrosion rate) per unit time was calculated from the mass decreased due to corrosion. Note that the sampling position of the test piece 1 is the top of the VAR secondary ingot. Part, Mid. Bot. The samples were collected from three places equivalent to each other and used in the test of the examples.
溶液のpH:pH≒0(常温)
浸漬時間:96時間
・耐熱(沸騰)塩酸性試験結果
表5に鋳塊の3ヵ所から採取した試験片について耐熱(沸騰)塩酸性を調査した結果を示す。なお特許文献3の製造方法で鋳込んだ材料は熱間加工性が不芳で板材を得ることができなかったため、耐熱(沸騰)塩酸性は評価していない。 Solution concentration and temperature: 3% hydrochloric acid (boiling state)
Solution pH: pH≈0 (room temperature)
Immersion time: 96 hours ・ Results of heat resistance (boiling) hydrochloric acid test Table 5 shows the results of examining the heat resistance (boiling) hydrochloric acid properties of test pieces taken from three locations of the ingot. In addition, since the material cast by the manufacturing method of patent document 3 was unsatisfactory in hot workability and a board | plate material was not able to be obtained, heat-resistant (boiling) hydrochloric acid property was not evaluated.
Claims (4)
- Ruを含有する耐食チタン合金の製造方法において、
含有量が10~40質量%のRuと、含有量が2~30質量%であるとともにRuの含有量の1/6以上の希土類元素とを含有し、かつ融点が2000℃以下の母合金を溶製して凝固し、
凝固後の母合金を粉砕し、
粉砕後の母合金とスポンジチタンとを混合して溶解炉で溶解する、Ruを含有する耐食チタン合金の製造方法。 In the method for producing a corrosion-resistant titanium alloy containing Ru,
A mother alloy having a Ru content of 10 to 40% by mass, a rare earth element having a content of 2 to 30% by mass and 1/6 or more of the Ru content, and a melting point of 2000 ° C. or less. Melted and solidified,
Crush the mother alloy after solidification,
A method for producing a corrosion-resistant titanium alloy containing Ru, wherein a mother alloy after pulverization and sponge titanium are mixed and melted in a melting furnace. - 前記母合金中の前記希土類元素の含有量は、前記耐食チタン合金中の希土類元素の含有量が合計で0.10質量%以下となる量に調整された量である、請求項1に記載のRuを含有する耐食チタン合金の製造方法。 2. The content of the rare earth element in the master alloy is an amount adjusted to an amount in which the content of rare earth elements in the corrosion-resistant titanium alloy is 0.10 mass% or less in total. A method for producing a corrosion-resistant titanium alloy containing Ru.
- 前記耐食チタン合金は、Ru元素が0.01~0.15質量%であり、希土類元素が合計で0.001質量%以上、残部がTiおよび不可避的不純物からなる合金組成を有する、請求項2に記載のRuを含有する耐食チタン合金の製造方法。 The corrosion-resistant titanium alloy has an alloy composition in which a Ru element is 0.01 to 0.15 mass%, a total of rare earth elements is 0.001 mass% or more, and the balance is Ti and inevitable impurities. A method for producing a corrosion-resistant titanium alloy containing Ru as described in 1.
- 前記耐食チタン合金は、不純物元素であるFe含有量が0.30質量%以下である、請求項1に記載のRuを含有する耐食チタン合金の製造方法。 The method for producing a corrosion-resistant titanium alloy containing Ru according to claim 1, wherein the corrosion-resistant titanium alloy has an Fe content as an impurity element of 0.30 mass% or less.
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