JP2010270360A - Titanium alloy material, structural member, and vessel for radioactive waste - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a low-cost titanium alloy material which exhibits excellent corrosion resistance in non-oxidizing environments such as a sulfuric acid environment, a high temperature neutral chloride environment and a fluoride-containing high temperature neutral chloride environment, to provide a structural member using the titanium alloy material, and to provide a vessel for radioactive waste using the titanium alloy material. <P>SOLUTION: The titanium alloy material comprises, by mass, 0.005 to 0.10% Ru, 0.005 to 0.10% Pd, 0.01 to 2.0% Ni, 0.01 to 2.0% Cr, 0.01 to 2.0% V and the balance Ti with inevitable impurities. Further, the structural member and the vessel for radioactive waste are obtained by using the titanium alloy material. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a titanium alloy material that is low in cost and excellent in corrosion resistance, and particularly used in a non-oxidizing environment such as a sulfuric acid environment, a high-temperature neutral chloride environment, or a high-temperature neutral chloride environment containing fluoride. The present invention relates to a titanium alloy material suitable for this, a structural member using the titanium alloy material, and a radioactive waste container using the titanium alloy material.

  Titanium has excellent corrosion resistance and is used in various fields such as chemical plants, offshore structures, and building materials. The corrosion resistance of titanium greatly depends on the stability of the passive film formed on the surface in the use environment. Titanium exhibits excellent corrosion resistance by forming a stable passive film on the surface in an oxidizing acid such as nitric acid and a room temperature chloride environment such as seawater. However, when non-oxidizing environment (sulfuric acid, high-concentration salt water, etc.) has low oxidizing power, the formation of a stable passive film mainly composed of titanium oxide is insufficient and the corrosion resistance is not so good. There is.

  In order to cope with the problem of corrosion resistance in such a non-oxidizing environment, alloys having further improved corrosion resistance by adding various alloy elements to titanium have been developed. For example, a Ti—Pd alloy is an alloy having excellent corrosion resistance even in a non-oxidizing environment, because Pd makes the potential of titanium noble and the passive film becomes more stable. Industrially, Ti-0.15 mass% Pd alloy is standardized as ASTM Grade 7 or Grade 11, and is used in fields such as petroleum refining and petrochemical plants that require extremely high corrosion resistance. However, the Ti-0.15 mass% Pd alloy has a problem in that the material cost is increased because a relatively large amount of expensive Pd is added.

  As a titanium alloy that is cheaper and exhibits excellent corrosion resistance, a Ti alloy in which a small amount of a platinum group element that exhibits an effect of improving corrosion resistance due to potential nobleness is added in combination with Pd, and further, other alloy elements are added. Has been developed. For example, a Ti-0.05 mass% Pd-0.3 mass% Co alloy has been developed and standardized as ASTM Grade 30 and Grade 31. Patent Document 1 discloses a titanium alloy to which platinum group elements, Cr and Ni are added. Patent Document 2 discloses titanium whose corrosion resistance has been improved by optimizing the ratio of Pd and platinum group elements other than Pd. An alloy is disclosed.

Japanese Patent Laid-Open No. 4-308051 JP 2000-248324 A

However, the conventional titanium alloy material has the following problems.
Normally, when titanium alloys are used as building materials in the atmospheric environment, there are no problems such as significant pitting corrosion or crevice corrosion, but surface discoloration due to corrosion may be taken up as a problem in the landscape, and sulfuric acid acidity In order to cope with an acid rain environment in an industrial area or the like that is exposed to water, further improvement in corrosion resistance is required at a low cost.

  Titanium alloys have high needs in high-temperature neutral chloride environments, such as condensers for thermal and nuclear power plants and heat transfer tubes for seawater desalination plants. There is a need for improvement. In particular, crevice corrosion often occurs due to chloride concentration under the structural gap forming portion or the deposit on the titanium alloy surface, and improvement in crevice corrosion resistance is required.

  Furthermore, in a container for transporting or disposing of radioactive waste generated from nuclear facilities such as nuclear fuel manufacturing facilities, nuclear power plants, nuclear fuel reprocessing facilities, the metal surface temperature of the container is 100 due to heat generation of the radioactive waste. May rise to over ℃. Therefore, during transportation or disposal, it is assumed that a highly concentrated solution in which chloride, fluoride, or the like, which is a corrosion promoting factor, is concentrated on the surface of the container as the moisture evaporates, resulting in a severe corrosive environment. In addition, fluoride is known to corrode titanium in an acidic region having a pH of 6 or less, and there is a problem in corrosion resistance in an acidic chloride environment containing fluoride.

  The present invention has been made in view of the above problems, and its purpose is in a non-oxidizing environment such as a sulfuric acid environment, a high temperature neutral chloride environment, or a high temperature neutral chloride environment containing fluoride. An object of the present invention is to provide a titanium alloy material exhibiting excellent corrosion resistance at a low cost, a structural member using the titanium alloy material, and a radioactive waste container using the titanium alloy material.

  As a result of examining the corrosion resistance improvement in a non-oxidizing environment, the present inventors have found that the combined addition of Ru and Pd is the most effective as a platinum group element, and in addition to these, Ni, Cr, and V are combined. It has been found that the corrosion resistance is the best when added. Specifically, it is as follows.

  The combined addition of Ru and Pd has the effect of making the potential of titanium noble and forming a stable passive film mainly composed of titanium oxide on the surface as described above. At this time, by adding Ni, Cr, and V simultaneously with Ru and Pd, the surface concentration of Ru and Pd on the titanium alloy surface in a non-oxidizing environment is promoted, and stable even when there is little Ru and Pd. The effect of forming a passive film becomes remarkable. Note that Ni is an element that contributes to improving corrosion resistance by forming a stable oxide even in a non-oxidizing environment. Furthermore, Ni, Cr, and V contribute to improving corrosion resistance by forming a stable composite fluoride protective film on the titanium alloy surface in an environment containing fluoride. It is considered that excellent corrosion resistance is expressed by the synergistic effect of each additive element as described above.

  In addition to the above elements, addition of appropriate amounts of Al, Si, and Fe is effective in improving corrosion resistance against fluorides, and by adding appropriate amounts of Os, Rh, Ir, and Pt, even better corrosion resistance is achieved. It has also been found that can be obtained.

  That is, the titanium alloy material according to the present invention has Ru: 0.005 to 0.10% by mass, Pd: 0.005 to 0.10% by mass, Ni: 0.01 to 2.0% by mass, Cr: 0. .01-2.0 mass%, V: 0.01-2.0 mass% is contained, The remainder consists of Ti and an unavoidable impurity, It is characterized by the above-mentioned.

  According to such a configuration, when the titanium alloy material contains a predetermined amount of Ru and Pb, the potential of titanium becomes noble and a stable passive film mainly composed of titanium oxide is formed on the surface. Furthermore, by containing a predetermined amount of Ni, Cr, and V, the surface concentration of Ru and Pd on the surface of the titanium alloy is promoted in a non-oxidizing environment, and the formation of a stable passive film is promoted. In an environment containing a fluoride, a stable composite fluoride protective film is formed on the surface of the titanium alloy. In addition, by containing a predetermined amount of Ni, a stable oxide is formed on the titanium alloy surface in a non-oxidizing environment.

  The titanium alloy material according to the present invention is further selected from Al: 0.005-2.0 mass%, Si: 0.005-2.0 mass%, and Fe: 0.005-2.0 mass%. It is preferable to contain at least one selected from the above.

  According to such a configuration, the titanium alloy material further contains Al, Si, and Fe in a predetermined amount, whereby the corrosion resistance to fluoride is further improved and the strength is also improved.

  The titanium alloy material according to the present invention further includes Os: 0.005 to 0.10% by mass, Rh: 0.005 to 0.10% by mass, Ir: 0.005 to 0.10% by mass, and Pt. : It is preferable to contain at least 1 sort (s) chosen from 0.005-0.10 mass%.

  According to such a configuration, the titanium alloy material further contains a predetermined amount of Os, Rh, Ir, and Pt, so that the potential of titanium becomes noble and a stable passive state mainly composed of titanium oxide. A film is formed on the surface. Thereby, the corrosion resistance in a non-oxidizing environment further improves.

The structural member according to the present invention is characterized by using the above-described titanium alloy material.
According to such a configuration, since the titanium alloy material having excellent corrosion resistance in a non-oxidizing environment such as a sulfuric acid environment, a high-temperature neutral chloride environment, or a high-temperature neutral chloride environment containing fluoride is used, The structural member has excellent corrosion resistance in an oxidizing environment.

The radioactive waste container according to the present invention is characterized by using the titanium alloy material described above.
According to such a configuration, the titanium alloy material having excellent corrosion resistance in a non-oxidizing environment such as a sulfuric acid environment, a high temperature neutral chloride environment, or a high temperature neutral chloride environment containing fluoride is used. It becomes a container for radioactive waste that can be adapted even in a severe corrosive environment caused by waste.

  The titanium alloy material according to the present invention exhibits excellent corrosion resistance even in a non-oxidizing environment such as a sulfuric acid environment, a high temperature neutral chloride environment, or a high temperature neutral chloride environment containing fluoride. Furthermore, the cost is low and the economy is excellent.

  The structural member according to the present invention is a member of a petroleum refining or petrochemical plant, offshore structure, building material, etc. exposed to a non-oxidizing environment, such as a condenser of a thermal power / nuclear power plant or a desalination plant. It can be suitably used for a heat pipe or the like.

  Since the radioactive waste container according to the present invention can be adapted even in a severe corrosive environment due to the radioactive waste, it is suitable as a container for transporting or disposing of the radioactive waste.

(A)-(c) is a schematic diagram which shows the test piece used for an Example.

  Next, the titanium alloy material, the structural member, and the radioactive waste container according to the present invention will be described in detail.

≪Titanium alloy material≫
The titanium alloy material according to the present invention has Ru: 0.005 to 0.10% by mass, Pd: 0.005 to 0.10% by mass, Ni: 0.01 to 2.0% by mass, Cr: 0.01 -2.0 mass%, V: 0.01-2.0 mass% is contained, remainder consists of Ti and an unavoidable impurity.
The titanium alloy material may further contain a predetermined amount of at least one selected from Al, Si, and Fe, and in addition to these, at least one selected from Os, Rh, Ir, and Pt. A predetermined amount of seed may be contained.
Hereinafter, the reasons for limiting the components will be described.

<Ru: 0.005 to 0.10% by mass>
Ru is an additive element effective for making the potential of titanium noble in a non-oxidizing environment and forming a stable passive film mainly composed of titanium oxide on the surface of the titanium alloy. In order to exhibit such an effect, it is necessary to contain 0.005 mass% or more. On the other hand, when the Ru content exceeds 0.10% by mass, such an effect is saturated and Ru is an expensive element, which is not preferable in terms of cost. Therefore, the Ru content is set to 0.005 to 0.10% by mass. In addition, 0.008 mass% or more is preferable and, as for Ru content, 0.010 mass% or more is more preferable. Moreover, 0.095 mass% or less is preferable, and 0.090 mass% or less is more preferable.

<Pd: 0.005 to 0.10% by mass>
Pd is an additive element that is effective for making the potential of titanium noble and forming a stable passive film mainly composed of titanium oxide on the surface of the titanium alloy in a non-oxidizing environment, and in particular coexist with Ru. Therefore, the effect becomes remarkable. In order to exhibit the effect of such Pd, it is necessary to contain 0.005 mass% or more. On the other hand, when the Pd content exceeds 0.10% by mass, such an effect is saturated, and Pd is an expensive element, which is not preferable in terms of cost. Therefore, Pd content shall be 0.005-0.10 mass%. In addition, 0.008 mass% or more is preferable and, as for Pd content, 0.010 mass% or more is more preferable. Moreover, 0.095 mass% or less is preferable, and 0.090 mass% or less is more preferable.

<Ni: 0.01 to 2.0% by mass>
Ni is an element that promotes surface concentration of Ru and Pd in a non-oxidizing environment by coexistence with Cr and V. In addition, Ni is an element that forms a stable oxide on the titanium alloy surface in a non-oxidizing environment, and further, in an environment containing fluoride, a stable composite fluoride protective film is formed on the titanium alloy surface, It is an element that contributes to improving corrosion resistance. In order to exert such effects, it is necessary to contain 0.01% by mass or more. However, if the added amount is excessive, weldability and hot workability deteriorate, so the Ni content is 2.0% by mass or less. Therefore, the Ni content is 0.01 to 2.0 mass%. The Ni content is preferably 0.03% by mass or more, and more preferably 0.05% by mass or more. Moreover, 1.95 mass% or less is preferable and 1.90 mass% or less is more preferable.

<Cr: 0.01 to 2.0% by mass>
Cr is an element that promotes surface concentration of Ru and Pd in a non-oxidizing environment by coexistence with Ni and V. Furthermore, in an environment containing fluoride, it is an element that contributes to improving corrosion resistance by forming a stable protective film of composite fluoride on the titanium alloy surface. In order to exert such effects, it is necessary to contain 0.01% by mass or more. However, if the addition amount is excessive, weldability and hot workability deteriorate, so the Cr content is set to 2.0 mass% or less. Therefore, Cr content shall be 0.01-2.0 mass%. The Cr content is preferably 0.03% by mass or more, and more preferably 0.05% by mass or more. Moreover, 1.95 mass% or less is preferable and 1.90 mass% or less is more preferable.

<V: 0.01 to 2.0% by mass>
V is an element that promotes surface concentration of Ru and Pd in a non-oxidizing environment by coexistence with Ni and Cr. Furthermore, in an environment containing fluoride, it is an element that contributes to improving corrosion resistance by forming a stable protective film of composite fluoride on the titanium alloy surface. In order to exert such effects, it is necessary to contain 0.01% by mass or more. However, if the addition amount is excessive, weldability and hot workability deteriorate, so the V content is set to 2.0 mass% or less. Therefore, V content shall be 0.01-2.0 mass%. In addition, 0.03 mass% or more is preferable and, as for V content, 0.05 mass% or more is more preferable. Moreover, 1.95 mass% or less is preferable and 1.90 mass% or less is more preferable.

<At least one selected from Al: 0.005-2.0 mass%, Si: 0.005-2.0 mass%, and Fe: 0.005-2.0 mass%>
Al, Si, and Fe are not effective elements for corrosion resistance against hydrochloric acid and sulfuric acid, but are elements that are effective for improving corrosion resistance to fluoride when added in a small amount, and are also effective for improving strength. . In order to exhibit such an effect, it is necessary to contain 0.005 mass% or more, respectively. However, when added excessively, in addition to greatly deteriorating the corrosion resistance in an acidic environment, the workability is also greatly degraded. Therefore, the upper limit of these contents is 2.0% by mass. Therefore, when adding Al, Si, and Fe, it is set as 0.005-2.0 mass%, respectively. In addition, Al, Si, and Fe content are each preferably 0.008 mass% or more, and more preferably 0.010 mass% or more. Moreover, 1.95 mass% or less is preferable respectively, and 1.90 mass% or less is more preferable.

<Os: 0.005-0.10 mass%, Rh: 0.005-0.10 mass%, Ir: 0.005-0.10 mass%, and Pt: 0.005-0.10 mass% At least one selected from
Os, Rh, Ir and Pt are elements that make the potential of titanium noble and promote the formation of a stable passive film and contribute to the improvement of corrosion resistance. In order to exhibit such an effect, it is necessary to contain 0.005 mass% or more, respectively. However, when added excessively, the workability is greatly deteriorated, so the upper limit of these contents is 0.10% by mass. Therefore, when adding Os, Rh, Ir, and Pt, it is set as 0.005-0.10 mass%, respectively. The Os, Rh, Ir, and Pt contents are each preferably 0.008% by mass or more, and more preferably 0.010% by mass or more. The Os, Rh, Ir, and Pt contents are each preferably 0.095% by mass or less, and more preferably 0.090% by mass or less.

<Balance: Ti and inevitable impurities>
The components of the titanium alloy material are as described above, and the balance consists of Ti and inevitable impurities. Inevitable impurities are permissible as long as they do not impair various properties of the titanium alloy material. For example, N is up to about 0.03 mass%, C is up to about 0.08 mass%, H is up to about 0.02 mass%, and O is up to about 0.3 mass%. There is no problem with the inclusion of these elements, and the effect of improving the corrosion resistance of the present invention is also obtained.

≪Manufacturing method≫
Next, an example of a method for producing a titanium alloy material according to the present invention will be described.
First, various metals and alloys are melted to produce a titanium alloy ingot having the above composition. After forging the obtained ingot at a heating temperature of 950 to 1050 ° C., hot rolling is performed at 800 to 900 ° C. to obtain a predetermined plate thickness. Next, after annealing at 700 to 900 ° C. for 10 to 60 minutes, a titanium composite material having a predetermined thickness is produced by cold rolling.

≪Structural member≫
The structural member according to the present invention uses the titanium alloy material described above.
As described above, the titanium alloy material of the present invention has excellent corrosion resistance in a non-oxidizing environment such as a sulfuric acid environment, a high temperature neutral chloride environment, or a high temperature neutral chloride environment containing fluoride. It can be used as an oil refining or petrochemical plant, offshore structure, building material, etc. For example, it can be used for a condenser of a thermal power / nuclear power plant, a heat transfer pipe of a seawater desalination plant, or the like.

≪Container for radioactive waste≫
The radioactive waste container according to the present invention uses the titanium alloy material described above.
As described above, in the container for transporting or disposing of radioactive waste generated from nuclear facilities such as nuclear fuel manufacturing facilities, nuclear power plants, nuclear fuel reprocessing facilities, the metal surface temperature of the container due to heat generation of the radioactive waste Becomes a high-temperature solution, and a high-concentration solution in which chlorides and fluorides, which are corrosion promoting factors, are concentrated is formed, resulting in a severe corrosive environment.
Therefore, by using the titanium alloy material of the present invention, it is possible to provide a radioactive waste container that can be adapted even in such a severe corrosive environment.

  Next, the titanium alloy material, the structural member, and the radioactive waste container according to the present invention will be specifically described by comparing an example that satisfies the requirements of the present invention with a comparative example that does not satisfy the requirements of the present invention.

<Production of test material>
Using a vacuum arc melting furnace, a total of about 500 g of various metals and alloys as melting raw materials were melted to prepare various titanium alloy ingots. The chemical composition is as shown in Table 1 (the balance is Ti and inevitable impurities). The obtained ingot was forged at a heating temperature of 1000 ° C., and then hot rolled at 870 ° C. to obtain a plate thickness of 5 mm. Next, after annealing at 750 ° C. for 20 minutes, a titanium alloy plate material having a thickness of 3 mm was produced by cold rolling. From the obtained titanium alloy plate material, a test piece A (FIG. 1 (a), TP-A) having a length of 50 mm × width 30 mm × thickness 2 mm and a test piece B (length 30 mm × width 30 mm × thickness 2 mm) FIG. 1 (b), TP-B) was cut out.

  Moreover, in order to suspend a test piece at the time of a corrosion test, the hole of (phi) 3mm was made in the edge part of TP-A. Moreover, in order to investigate crevice corrosion characteristics, the crevice corrosion test piece (test material) C which overlapped and bolted TP-A and TP-B of the same material was also produced (FIG.1 (c), (d) ). In the crevice corrosion test piece C, the test solution soaks into the mating surface (gap) of TP-A and TP-B, causing salt concentration and pH reduction, resulting in severe corrosion conditions from the outside of the gap, resulting in crevice corrosion. Depending on the type of test piece C, corrosion progresses (crevice corrosion). The crevice corrosion test piece C is a TP-A and TP-B with a 5 mm hole in the center and tightened with a pure titanium bolt and nut. At this time, the tightening torque is 8.5 N · m, and a threaded portion of a pure titanium bolt is covered with a silicon tube, and a polytetrafluoroethylene (PTFE) washer (PTFE washer) is sandwiched between the TP-A or Dissimilar metal contact between TP-B and bolts and nuts was prevented. In addition, all TP-A and TP-B were used for the test after grind | polishing the whole surface to SiC # 600 with the wet rotary grinder, and washing with water and acetone.

<Corrosion test method>
As the corrosive environment, corrosion resistance was evaluated in three types of non-oxidizing solutions: (1) sulfuric acid aqueous solution, (2) salt water, and (3) salt water containing fluoride. As for the corrosive environment (1), an immersion corrosion test in a boiling 5% H ₂ SO ₄ aqueous solution was performed, and the corrosion weight loss determined from the mass change before and after the immersion test was evaluated. Immersion time is 72 hours. First, the test solution was put into a 1 L round bottom flask and heated by a mantle heater to boil. After the solution boiled, a test piece A (TP-A) was hung and immersed as a test material using PTFE yarn. At this time, a cooling tube was installed in the flask to prevent evaporation of the solution. The specific solution amount of the test solution is 1 L for each test piece (test material). In this test, No. 1 shown in Table 1 was used. Five to one titanium alloy materials of 1 to 40 were tested, and the average value of five pieces was calculated for the corrosion weight loss. The mass after the test was measured after the test piece A after immersion was washed with water and acetone and dried.

  For the corrosive environment (2), a crevice corrosion test piece (test material) was immersed in a boiling 20% NaCl aqueous solution, and the presence or absence of crevice corrosion on the mating surface of the crevice corrosion test piece C was examined. First, as in the above (1), the test solution was placed in a 1 L round bottom flask and heated with a mantle heater to boil. After the solution boiled, the crevice corrosion test piece C was hung and immersed as a test material using PTFE yarn. The immersion time is 30 days. At this time, a cooling tube was installed in the flask to prevent evaporation of the solution. The specific volume of the test solution is 1 L per test piece (test material). In this test, No. 1 shown in Table 1 was used. Five to one titanium alloy materials of 1 to 40 were tested, and crevice corrosion occurrence probability (= number of test pieces in which crevice corrosion occurred / 5 × 100 (%)) was determined. In addition, the presence or absence of crevice corrosion generate | occur | produced and the crevice corrosion test piece C after completion | finish of a test was disassembled and wash | cleaned, and it was determined that crevice corrosion had generate | occur | produced when the corrosion hole of depth 10micrometer or more was recognized.

  As for the corrosive environment (3), an immersion corrosion test was performed in a boiling 20% NaCl + 0.01% NaF aqueous solution adjusted to pH 4.0, and evaluation was performed based on the corrosion weight loss obtained from the mass change before and after the immersion test. The immersion time is 30 days. First, an appropriate amount of HCl was added to a 20% NaCl + 0.01% NaF aqueous solution at room temperature to adjust the pH of the solution to 4.0. Next, the test solution was placed in a 1 L round bottom flask and heated with a mantle heater to boil. After the solution boiled, a test piece A (TP-A) was hung and immersed as a test material using PTFE yarn. At this time, a cooling tube was installed in the flask to prevent evaporation of the solution. The specific volume of the test solution is 1 L per test piece (test material). In this test, No. 1 shown in Table 1 was used. Five to one titanium alloy materials of 1 to 40 were tested, and the average value of five pieces was calculated for the corrosion weight loss. The mass after the test was measured after the test piece A after immersion was washed with water and acetone and dried.

  For the corrosion tests in these two types of non-oxidizing solutions, (1) sulfuric acid aqueous solution and (3) salt water containing fluoride, the corrosion weight loss of each test material is No. The relative value when the corrosion weight loss of 35 (pure titanium) is taken as 100 is shown. As a comprehensive evaluation, no crevice corrosion was observed in the salt water of (2) (the crevice corrosion occurrence probability was 0), and the corrosion weight loss relative value in each acid solution of (1) and (3) above. However, both of which are 2 or less (corrosion weight loss is 1/50 or less of No. 35), the corrosion resistance is very good (◎), and at least one exceeds 2 and 5 (corrosion weight loss is No. 35). 1/50 and 1/20 or less) and both 5 or less are good (◎), any one or more exceeds 5 and 10 or less (corrosion weight loss is 1/20 of No. 35) Exceeding 1/10 or less) and 10 or less in both cases were evaluated as slightly good (◯). In addition, crevice corrosion was observed (probability of crevice corrosion occurrence was 20 or more), and in the relative value of corrosion weight loss in each acid solution of (1) and (3) above, any one or more exceeded 10. (Corrosion weight loss is more than 1/10 of No. 35). Corrosion weight loss (100) of 35 (pure titanium) was determined to be extremely poor (x).

  Table 1 shows the chemical composition of the test material, and Table 2 shows the results of the corrosion test. In Table 1, those not satisfying the scope of the present invention are indicated by underlining the numerical values, and those not containing a component are indicated by “−”.

  As shown in Tables 1 and 2, no. Since the titanium alloy materials 1 to 34 satisfy the scope of the present invention, no crevice corrosion was observed in the salt water, and the corrosion weight loss in the salt water containing the sulfuric acid aqueous solution and fluoride was No. It was 1/10 or less of 35 pure titanium, which resulted in excellent corrosion resistance. These corrosion resistances are manifested by the combined addition of Ru, Pd, Ni, Cr, and V.

On the other hand, no. Since 35-40 did not satisfy the scope of the present invention, the following results were obtained.
No. 35 was inferior in corrosion resistance because of pure titanium.
No. 36-No. No. 40 titanium alloy is No. Although the corrosion resistance was improved as compared with 35 pure titanium, the occurrence of crevice corrosion in salt water was observed, and the reduction in corrosion weight was not sufficient.
No. 36 and no. In No. 37, since the contents of Ru and Pd were less than the lower limit values, the potential of titanium was not so noble, the generation of a stable passive film was insufficient, and the corrosion resistance was poor.

  No. 38, no. 39 and no. In No. 40, since the contents of Ni, Cr and V are less than the lower limit values respectively, the surface concentration of Ru and Pd is not promoted, the potential of titanium is not so precious, and the generation of a stable passive film is insufficient. There was inferior corrosion resistance. Moreover, in the salt water containing a fluoride, the production | generation of the protective composite fluoride film | membrane of Ni, Cr, and V was inadequate, and it was inferior to corrosion resistance. In addition, No. No. 38 did not produce a stable oxide because the Ni content was less than the lower limit.

  As described above, any of the titanium alloy materials of the present invention has excellent corrosion resistance in a non-oxidizing environment and is suitable as a structural member. In particular, since the corrosion resistance in salt water containing fluoride is superior to conventional trace platinum group-added titanium alloy materials (No. 36 to No. 40), a high-concentration solution in which chloride, fluoride, etc. are concentrated It is suitable as a radioactive waste container for transporting or disposing of radioactive waste exposed to the environment.

  As described above, the titanium alloy material, the structural member, and the radioactive waste container according to the present invention have been described in detail with reference to the embodiments and examples. However, the gist of the present invention is not limited to the contents described above. Needless to say, the contents of the present invention can be widely modified and changed based on the above description.

A Test piece (TP-A)
B Test piece (TP-B)
C Crevice corrosion test piece

Claims (5)

  Ru: 0.005-0.10 mass%, Pd: 0.005-0.10 mass%, Ni: 0.01-2.0 mass%, Cr: 0.01-2.0 mass%, V: A titanium alloy material characterized by containing 0.01 to 2.0% by mass, the balance being Ti and inevitable impurities.   Furthermore, it contains at least one selected from Al: 0.005-2.0 mass%, Si: 0.005-2.0 mass%, and Fe: 0.005-2.0 mass%. The titanium alloy material according to claim 1, wherein the material is a titanium alloy material.   Furthermore, Os: 0.005-0.10 mass%, Rh: 0.005-0.10 mass%, Ir: 0.005-0.10 mass%, and Pt: 0.005-0.10 mass The titanium alloy material according to claim 1, wherein the titanium alloy material contains at least one selected from%.   A structural member using the titanium alloy material according to any one of claims 1 to 3.   A radioactive waste container, wherein the titanium alloy material according to any one of claims 1 to 3 is used.

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