JPH10265866A - Production of vanadium-containing base alloy for producing titanium alloy - Google Patents

Abstract

PROBLEM TO BE SOLVED: To continuously draw out a low oxygen base alloy as an ingot without developing the crack by using an electronic beam to melt a vanadium-containing alloy in a specific vacuum degree and deoxidizing. SOLUTION: As the vanadium-containing alloy used as the raw material, an alloy composed of aluminum and vanadium, is suitable. Further, the vanadium content in the alloy is desirable to be >=75 wt.%. The vanadium-containing base alloy is melted under high vanadium of 10<-3> -10<-6> Torr by using the electronic beam and the deoxidizing treatment is executed. As the deoxidizing treatment, the well-known electronic beam melting method, etc., is mentioned. By this method, the oxygen content is reduced in the refined vanadium- containing base alloy and as the other result, iron content as impurity can be reduced. Then, at the time of drawing out as the ingot, this ingot can continuously be drawn out without developing the crack caused by heat strain.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a method for producing a low oxygen vanadium-containing master alloy used for producing a titanium alloy.

[0002]

2. Description of the Related Art When producing a titanium alloy ingot, alloy components are often added as a master alloy. This lowers the melting point by making each alloy component a master alloy,
This is for facilitating dissolution. For example, molybdenum is 2
It has a melting point of 610 ° C and a density of 10.23 g / cm
^When the metal is melted by the consumable electrode type vacuum arc melting method, it may not be sufficiently melted even if it is added as a single metal. Aluminum (35) / molybdenum (65) or aluminum (50) / molybdenum (2
In the case of a 5) / vanadium (25) master alloy, the melting points are lowered to 1850 ° C. and 1440 ° C., respectively, so that it can be easily melted. On the other hand, in titanium alloys, especially in many applications such as aircraft and space technology, extreme requirements are imposed on alloy components and purity, and particularly on oxygen content, since it has a significant effect on mechanical properties, Low content is required. Conventionally, as a degassing process including deoxidation of a vanadium-containing master alloy used when manufacturing a titanium alloy, for example, in the case of an aluminum / vanadium master alloy, a vacuum induction furnace melting method or a high-frequency melting method is used. And the oxygen content after treatment is about 0.
It has been reduced to a level of 1%.

[0003]

However, in the above-described vacuum induction furnace melting method, when the content ratio of vanadium in the alloy is increased, the melting point of the aluminum / vanadium alloy after the thermite reaction becomes high, so that melting becomes difficult. for example,
Even if it is possible to raise the temperature to such a high melting point, the refractory of the furnace will be damaged and impurities will be mixed in the alloy, and it is not possible to actually perform deoxidation. It has to be commercialized without it. Also,
Even if a refining method other than the vacuum induction furnace melting method is used, there is a problem in that when it is taken out as a refined ingot, cracks occur due to heat distortion due to solidification and it cannot be continuously withdrawn. However, there remains a problem that the oxygen content is not sufficiently satisfactory.

Accordingly, an object of the present invention is to provide a vanadium-containing master alloy used in the production of a titanium alloy, in which a low-oxygen master alloy whose oxygen content is further reduced as compared with the oxygen content after the conventional deoxidation treatment is cracked. The present invention provides a method for continuously taking out an ingot without using it.

[0005]

Under such circumstances, the present inventors have conducted intensive studies and as a result, have found that a vanadium-containing alloy used for producing a titanium alloy can be reduced to 10 ^-3 to 10 ^-6 T.
It has been found that a very low oxygen master alloy can be obtained as a stable ingot without cracking by melting and deoxidizing using an electron beam under a high vacuum of orr, and completed the present invention. That is, the present invention provides a method for producing a vanadium-containing master alloy for titanium alloy production, which comprises melting and deoxidizing a vanadium-containing alloy using an electron beam under a vacuum of 10 ^-3 to 10 ^-6 Torr. To provide.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION In the method of the present invention, the vanadium-containing alloy used as a raw material is not particularly limited. For example, an aluminum / vanadium master alloy (hereinafter referred to as Al-
V mother alloy), aluminum / molybdenum / vanadium master alloy (hereinafter abbreviated as Al-Mo-V master alloy), aluminum / tin / vanadium master alloy, and aluminum / chromium / vanadium master alloy. These contain slight impurities in the mother alloy in addition to the main components. The composition of the mother alloy of these vanadium-containing master alloys is not particularly limited, but after deoxidation treatment, that is, in the state of a raw material for titanium alloy production, in an Al-V master alloy, aluminum: vanadium is 0.5%. ~ 60: 9
9.5 to 40, preferably 0.5 to 25: 99.5 to 7
5, particularly preferably 12 to 17:88 to 83, more preferably 15:85. If the ratio of aluminum in the Al-V master alloy is too high, cracks due to thermal strain during solidification during continuous lowering of the ingot, which will be described later, are not preferred.
The alloy containing aluminum and vanadium as a raw material is obtained by manufacturing using a known thermite reaction.

In the present invention, the above vanadium-containing master alloy is melted using an electron beam under a high vacuum of 10 ^-3 to 10 ^-6 Torr, and deoxidized. As the deoxidizing method, for example, a known electron beam melting method (EB
R) and an ultrahigh vacuum electron beam floating zone melting method. The following is a specific example of the electron beam melting method. That is, as shown in FIG. 1, an EBR furnace 10 used in the electron beam melting method includes a raw material supply unit 1, a molten pool 7 formed at an upper portion to perform degassing, and a water-cooled copper that forms an ingot at a lower portion. It is formed from the crucible 2, the electron gun 3, and the ingot pulling jig 4. In the EBR furnace 10, 10 ^-3 to 10 ^-6 , preferably 10 ^-4 to 10 ^-5 Torr
Heating the hot cathode (filament) under a vacuum of r applies a high voltage to the generated thermoelectrons to accelerate them, and collides the hot electrons with the raw material fed from the raw material supply unit 1 to dissolve and remove the raw material. That is what gas. The method of supplying the raw material is not particularly limited, but a method of extruding the electrode 5 filled with the flake-form raw material into an aluminum cylinder by a feeder 6 and supplying the electrode 5 gradually and successively from one apparatus to another is used. Is preferred because the composition can be simplified and the composition can be easily adjusted. The electron gun 3 preferably has two or more electron guns, and an electron beam emitted from the electron gun may be applied to the molten pool and the tip of the electrode. As described above, while performing degassing in the melting pool 7, the ingot located below the furnace can take out the deoxidized purified ingot by continuously lowering the ingot lowering jig 4.

[0008] The purified ingot obtained by the above method is used again as a raw material for 10 ^-3 to 10 ^-6 Torr.
Melting using an electron beam under a vacuum of r and deoxygenation treatment is further preferred because a low-oxygen vanadium-containing mother alloy can be obtained. When producing a titanium alloy, it is preferable to use the refined ingot in the form of a chip when cutting it from the viewpoint of operability and the like.

In the present invention, the vanadium-containing master alloy purified by the above method can reduce the oxygen content and the iron content as an impurity.

As an example of a titanium alloy in which these deoxygenated master alloys are used, in the case of an Al-V master alloy,
-6Al-4V, Ti-15V-3Cr-3Al-3
Sn, Ti-6Al-6V-2Sn, Ti-3Al-
2.5V, Ti-4Al-3Mo-1V, Ti-13.
5V-11Cr-3Al and the like.
-15V-3Cr-3Al-3Sn is particularly preferred. If the manufacturing example of the Ti-6Al-4V alloy is shown, for example,
90% by weight of titanium sponge, A deoxygenated A
A raw material comprising 4% by weight of an IV master alloy and 6% by weight of Al shot may be uniformly melted by a vacuum arc melting method, then cooled and taken out as a titanium alloy ingot.
If necessary, the obtained titanium alloy ingot may be purified again by the vacuum arc melting method. The titanium alloy ingot thus obtained has an extremely low oxygen content and exhibits excellent properties such as mechanical strength.

[0011]

According to the method of the present invention, a very low oxygen vanadium-containing master alloy can be obtained, and cracks due to thermal strain are generated when the deoxidized vanadium-containing mother alloy is taken out as an ingot. And can be taken out continuously. Further, the deoxidized purified master alloy (ingot) can reduce iron as an impurity. In addition, when a titanium alloy is manufactured using a low oxygen vanadium-containing master alloy, a material having more excellent properties such as mechanical strength can be obtained.

[0012]

Next, the present invention will be described in more detail with reference to examples, but this is merely an example and does not limit the present invention. Example 1 Two kinds of vanadium-containing alloys having the following compositions obtained by the thermit reaction were used as raw materials, and a first deoxygenation treatment was performed by a known electron beam melting method under the following conditions. Next, the obtained low oxygen ingot was purified again under the same conditions. However, as shown in FIG. 2, in the second purification, the supply of the raw material ingot 8 was performed by the EBR furnace 1.
The electron beam was irradiated at an angle as shown in FIG. 2 while gradually descending while rotating the shaft 9 from above 0. The oxygen content followed the method described in JIS H1620. Table 1 shows the results.

Raw material A: 85V-15Al (particle size: 0.3-2.
5 mm, manufactured by GFE, composition: V; 83.7% by weight (hereinafter, weight%
), Al; 15.2, Fe; 0.29, O; 0.
17, N; 0.035, Si; 0.12) Raw material B: 50V-50Al (manufactured by GFE, composition: V; 52.
O, Al; 47, Fe; 0.3-0.35, O; 0.03-0.04, N; 0.02)

(Electron Beam Melting Method Test Conditions) Degree of vacuum; 10 ^-4 to 10 ^-5 Torr EBR furnace; manufactured by Leybold Heraus Co. (shown schematically in FIG. 1) Crucible inner diameter; 180 mm diameter Number of electron guns: 2 Ingot casting method;

Comparative Example 1 A method similar to that of Example 1 was followed except that a vacuum induction furnace melting method was used instead of the electron beam method. Vacuum induction furnace melting method (V
IM) are shown below, and the results are shown in Table 1. (Test method for vacuum induction furnace melting method) Degree of vacuum: 10 ^-2 to 10 ^-3 Torr VIM furnace; Refractory lining structure manufactured by Rybold Heraus Co .;

[0016]

[Table 1]

From Table 1, it can be seen that in Example 1, a vanadium-containing master alloy having a remarkably low oxygen content was obtained in both 50V-50Al and 85V-15Al. In particular, the second time of the deoxidation treatment showed an extremely remarkable oxygen reduction effect.

Reference Example 1 Production of Titanium Alloy Al deoxidized twice obtained in Example 1 and Comparative Example 1.
A Ti-6Al-4V alloy and a Ti-15V-3Cr-3Al-3Sn alloy were produced using two types of -V alloys, respectively. The production was performed by uniformly dissolving by the vacuum arc melting method so as to have the compositions shown in Tables 2 and 3, and then obtaining a titanium alloy ingot. Table 2 shows the results.

[0019]

[Table 2]

[0020]

[Table 3]

From Tables 2 and 3, it can be seen that when the mother alloy of the example was used, about 16% and β
In the case of alloys, the oxygen content can be reduced by about 50%, which further improves properties such as mechanical strength.

[Brief description of the drawings]

FIG. 1 is a schematic view of an electron beam melting furnace used in the method of the present invention.

FIG. 2 is a diagram showing a position of a raw material and an irradiation angle of an electron beam in a second deoxygenation process.

[Description of Signs] 1 Raw material supply unit 2 Water-cooled copper crucible 3 Electron gun 4 Ingot lowering jig 5 Electrode 6 Feeder 7 Melting pool 8 Refined ingot obtained in the first run 9 Shaft 10 EBR furnace

Claims (3)

[Claims] 1. A vanadium-containing alloy of 10 ^-3 to 10 ^-6 T
A method for producing a vanadium-containing master alloy for producing a titanium alloy, wherein the vanadium-containing mother alloy is melted and deoxidized using an electron beam under an orr vacuum. 2. The method according to claim 1, wherein the vanadium-containing alloy is an alloy composed of aluminum and vanadium. 3. The method for producing a vanadium-containing master alloy for titanium alloy production according to claim 1, wherein the vanadium-containing alloy has a vanadium content of 75% by weight or more.