WO2018155658A1 - Method for producing ti-al alloy - Google Patents

Abstract

The present invention is provided with: a primary ingot production step in which 3-20 mass% of a CaO-CaF2 flux obtained by mixing 35-95 mass% of calcium fluoride with calcium oxide, is added to a Ti-Al alloy material including a total of at least 0.1 mass% of oxygen, and at least 40 mass% of Al, and the resultant substance is melted by way of a melting method using a water-cooled copper container in an atmosphere having a pressure of 1.33 Pa or higher, and held, to produce a primary ingot; a secondary ingot production step in which the primary ingot is continuously drawn downwards while being melted by way of a melting method using a bottomless water-cooled copper casting mould in an atmosphere having a pressure of 1.33 Pa or higher, to obtain a secondary ingot Y; and a flux layer removal step in which a flux layer deposited on the surface of the secondary ingot Y is mechanically removed.

Description

Method for producing Ti-Al alloy

The present invention provides a high-grade or low-oxygen Ti—Al alloy by adding an aluminum raw material and a flux to a low-grade titanium raw material such as titanium oxide (TiO ₂ ) such as lower sponge titanium, scrap titanium, and rutile ore. The present invention relates to a method for producing a Ti—Al-based alloy.

In recent years, demand for Ti-Al alloys as materials for aircraft and automobiles has increased. Conventionally, Ti—Al alloys are very active against oxygen, so that the vacuum arc melting method (VAR), electron beam melting method (EB), plasma arc melting method (PAM), which can reduce the influence of oxygen, Melting and casting are performed using techniques such as vacuum induction melting (VIM) and water-cooled copper induction melting (CCIM).

Among the melting and casting methods described above, in the melting process based on a method such as VAR, EB, and VIM performed in a vacuum atmosphere, not only the alloy element Al but also Ti is lost due to volatilization. It is difficult to control the composition after dissolution, and there is a concern that the manufacturing cost will increase.

In general, high-quality raw materials with low oxygen content are used as titanium raw materials for melting Ti-Al alloys. Recently, however, the price of high-grade titanium raw materials has soared. Therefore, there is a growing need to obtain a high-quality, that is, low-oxygen Ti—Al alloy even when using titanium raw materials such as low-grade ores and scraps with a high oxygen content.

Therefore, instead of using melting methods such as VAR, EB, and VIM, where Ti loss is likely to occur due to volatilization, low-quality raw materials (over 0.1% by mass of oxygen content) are used by using melting methods such as PAM and CCIM. A technology for producing a Ti—Al-based alloy by deoxidation from a large amount of titanium raw material) while suppressing volatilization loss of Al and Ti has been proposed.

For example, in Patent Document 1, when PAM or CCIM is used and dissolved and held by adding 40% by mass or more of Al to high oxygen content Ti in an atmosphere of 1.33 Pa or higher, oxygen in the Ti—Al based alloy is reduced. combines with Al _Al 2 in the form of _{O 3} is discharged from in Ti-Al deoxidation progresses, and that the addition of flux CaO-CaF ₂ based, activity of _Al 2 _{O 3} is reduced Further, it is described that deoxidation further proceeds.

In the manufacturing method of Patent Document 1 described above, oxygen in the Ti—Al alloy is certainly discharged in the form of Al ₂ O ₃ and deoxidized. However, by simply dissolving and holding using PAM or CCIM, Al ₂ O ₃ which is a by-product of deoxidation and CaO—CaF ₂ flux added to promote deoxidation are Ti—Al alloys. In the Ti-Al alloy, the site where deoxidation has progressed and the site where deoxidation has not progressed (site where Al ₂ O ₃ remains) Will be mixed.

In Patent Document 1, low-grade Ti, in other words, high-grade Ti such as pure Ti is added to a Ti—Al-based alloy in which Al ₂ O ₃ or CaO—CaF ₂ -based flux is partially left. It is also described that if Al is diluted, a Ti—Al based alloy having an Al content of less than 40% by mass and a low oxygen content can be produced.

However, the Ti-Al-based alloy has parts _{which as Al} 2 _{O 3} and flux remaining, melting it in Ti-Al alloy of the Al content by adding pure Ti is less than 40 wt% When trying to do so, Al ₂ O _{3 and the} like inside the flux are decomposed / re-dissolved, and the oxygen concentration and the like are increased. Therefore, with the production method of Patent Document 1, it is not easy to obtain a high-quality, that is, low-oxygen Ti—Al-based alloy with an Al content of less than 40% by mass.

In addition, if the portion where Al ₂ O ₃ or the like remains is mechanically removed by cutting or the like and then dissolved by adding high-grade, that is, low-oxygen Ti, the low oxygen content of less than 40% by mass is obtained. A Ti-Al alloy can be obtained, but a part of the metal Ti is also removed at the time of mechanical removal of Al ₂ O ₃ etc., so the yield of the Ti-Al alloy becomes very poor. This leads to an increase in cost.

That is, in the deoxidation method of Patent Document 1, for a Ti—Al alloy containing 40 mass% or more of Al, how to use Al ₂ O ₃ or CaO—CaF ₂ flux in the Ti—Al alloy. If the Al ₂ O ₃ or CaO—CaF ₂ flux remains, it is important how to separate / remove the remaining flux and other substances from the Ti—Al alloy.

In this regard, Patent Documents 2 to 5 disclose techniques useful for separating / removing substances such as residual flux from Ti—Al based alloys.

For example, in Patent Document 2, when an active metal is continuously melted and solidified to cast an ingot by using a plasma arc as a heat source, a flux such as CaF ₂ is heated and melted in advance and then the active metal is charged. Alternatively, it is put together with the active metal, and a flux is contained between the water-cooled copper crucible and the ingot to slowly cool and solidify the surface of the ingot, thereby melting the ingot with a smooth ingot surface. Is described.

Patent Document 3 discloses a flux such as CaF ₂ when casting an ingot by continuously melting and solidifying titanium or a titanium alloy using a plasma-cooled water-cooled copper mold with a plasma arc as a heat source. By changing the addition amount according to the mold position, the effect of slowly cooling the interface between the water-cooled copper mold and the molten metal is developed, and as a result, casting a slab with a good casting surface condition Is described as being possible.

In Patent Document 4, a cold-crucible levitation and dissolution apparatus (CCIM) is used to add rare earth metal (cerium or misch metal in the examples) to Ti and calcium fluoride (CaF ₂ ) as a flux to Ti. Once melted, a molten flux can be present between the molten metal and the water-cooled copper crucible, and by transferring solid or liquid non-metallic inclusions to the molten flux layer, the molten metal improves the cleanliness of the molten metal. A purification method is described.

Generally, when a metal containing non-metallic inclusions is melted using a high-frequency induction furnace such as CCIM, the non-metallic inclusions have a lower electrical conductivity than metals such as Ti. It is known that there is a tendency to gather outside (water-cooled copper crucible side). Therefore, if the method of Patent Document 4 is used, non-metallic inclusions such as Al ₂ O ₃ may be localized and physically removed from the Ti—Al-based alloy.

Furthermore, Patent Document 5 discloses an induction melting furnace provided with a water-cooled copper crucible in which a crucible main body is movable in the vertical direction relative to the contents accommodated in the furnace. This Patent Document 5 also describes that a long active metal ingot is produced by repeatedly dissolving a metal raw material and lowering a water-cooled copper crucible. This Patent Document 5 is also similar to Patent Document 4 in that a high-frequency induction furnace equipped with a water-cooled copper crucible is used. In principle, non-metallic inclusions tend to gather outside the metal ingot. Therefore, there is a possibility that non-metallic inclusions such as Al ₂ O ₃ can be physically removed from the Ti—Al based alloy as in Patent Document 4.

International Publication No. 2016/035824 Japanese Unexamined Patent Publication No. 53-86603 Japanese Unexamined Patent Publication No. 2013-49084 Japanese Laid-Open Patent Publication No. 11-246919 Japanese Unexamined Patent Publication No. 2006-122920

With the method of Patent Document 2, Al ₂ O ₃ and CaO—CaF ₂ flux remaining in the Ti—Al based alloy, which is a problem in Patent Document 1, can be mechanically removed on the ingot surface. Although it can be discharged, the method of Patent Document 2 uses a flux such as CaF ₂ for the purpose of smoothing the cast surface of the ingot, and cannot be expected to have an effect of deoxidation or inclusion removal.

Further, as in the continuous casting method of Patent Document 3, a plasma arc is used as a heat source, and high oxygen Ti, Al, and CaO—CaF ₂ fluxes are continuously added to a bottomless water-cooled copper mold and melted downward. If withdrawn, the flux remains solid, or to coagulate migrate between the molten metal dissolves immediately after a water-cooled copper mold and Ti-Al alloy, it is dissolved Al ₂ O ₃ in the flux Al ₂ O Solidification is performed before the activity of ₃ is sufficiently reduced, and it is considered that the deoxidation promoting effect and inclusion removal effect due to the decrease in the activity of Al ₂ O ₃ can hardly be expected.

The method for refining molten metal disclosed in Patent Document 4 simply dissolves a metal containing non-metallic inclusions using a cold-crucible levitation and dissolution apparatus (CCIM), and a non-metal such as Al ₂ O _3. It is not a suitable condition for inclusions to migrate into the flux. Therefore, even if the transition of non-metallic inclusions to the flux occurs, the possibility that a sufficient amount of transition is performed is low, and there is a high possibility that the non-metallic inclusions remain in the molten metal (described later). In the comparative example 1 and the comparative example 2 of the example according to the second embodiment, the result that the nonmetallic inclusion remains is actually obtained).

In addition, even if the migration of nonmetallic inclusions such as Al ₂ O ₃ is sufficiently performed, Patent Document 4 does not describe how to treat the flux remaining in the molten metal. . In other words, if the flux remaining in the molten metal cannot be removed from the molten metal by any method, a Ti—Al alloy with high cleanliness cannot be obtained even using the technique of Patent Document 4.

In addition, the method for producing an active metal ingot of Patent Document 5 can in principle collect non-metallic inclusions on the outside of the metal ingot, as in Patent Document 4, but non-metallic inclusions. Since it is not a condition suitable for transferring to the flux, there is a possibility that non-metallic inclusions such as Al ₂ O ₃ in the Ti—Al alloy cannot be actually removed (second embodiment described later). In Comparative Example 3 of the example, a result in which nonmetallic inclusions remain is actually obtained).

Furthermore, Patent Document 5 does not assume dissolution with addition of flux, and there is no description regarding deoxidation and inclusion removal. Therefore, it is unclear whether deoxidation or inclusion removal can be performed without any problems when the pulling-down is performed at the pulling-down rate specified in Patent Document 5. For example, in Patent Document 5, the speed at the time of lowering is set to 30 mm or less per minute. However, in such a fast lowering speed, the flux layer breaks and the molten metal leaks out, so that deoxidation is ensured. It may not be done.

The present invention has been made in view of the above-mentioned problems. From a low-grade titanium material containing a high concentration of oxygen, a high-grade and low-oxygen Ti—Al alloy is efficiently produced with a high yield. It is an object of the present invention to provide a method for producing a Ti—Al based alloy that can be produced.

In order to solve the above problems, the manufacturing method of the Ti—Al based alloy of the present invention takes the following technical means.
That is, the method for producing a Ti—Al based alloy of the present invention is based on a Ti—Al based alloy comprising a titanium material and an aluminum material and containing a total of 0.1 mass% or more of oxygen and 40 mass% or more of Al. A dissolved raw material obtained by adding a CaO—CaF ₂ -based flux in which 35 to 95% by mass of calcium fluoride is mixed with calcium oxide to 3 to 20% by mass with respect to the Ti—Al-based alloy is added to 1.33 Pa. A primary ingot manufacturing process in which the primary ingot is melted by melting and holding by a melting method using a water-cooled copper container in the above atmosphere, and the primary ingot is bottomless in an atmosphere of 1.33 Pa or more A secondary ingot manufacturing step for continuously drawing a secondary ingot while being melted by a melting method using a water-cooled copper mold, and a flux for mechanically removing the surface adhering flux layer of the secondary ingot A layer removal step, Characterized by (hereinafter sometimes referred to this embodiment the first embodiment).

Further, another Ti—Al based alloy production method of the present invention is a Ti—Al based alloy comprising a titanium material and an aluminum material and containing a total of 0.1 mass% or more of oxygen and 40 mass% or more of Al. On the other hand, a melting raw material in which CaO—CaF ₂ flux containing 35 to 95% by mass of calcium fluoride and calcium oxide is mixed to 3 to 20% by mass with respect to the Ti—Al alloy is cast. The raw material dividing step of dividing n so that the weight of the molten raw material after the division becomes a maximum of 4/5 or less with respect to the final target ingot weight at the end, and the molten raw material divided in the raw material dividing step The first divided body is charged into a bottomless water-cooled copper mold, dissolved in an inert gas atmosphere of 1.33 Pa or higher, and the bottom of the water-cooled copper mold is pulled down at a rate of 15 mm or less per minute. Done, then The melted raw material second divided body divided in the raw material dividing step is charged into the water-cooled copper mold and dissolved in an inert gas atmosphere of 1.33 Pa or more, and the water-cooled copper mold is 15 mm or less per minute. The operation of pulling down at a speed is performed, and thereafter, the above-described operation is repeated up to the n-th divided body to obtain an ingot, and the ingot formed in the divided body-based ingot manufacturing process. And a flux layer removing step of mechanically removing the flux layer adhering to the surface (hereinafter, this embodiment may be referred to as a second embodiment).

Preferably, a titanium material is added to the ingot after the flux layer removing step and dissolved by a melting method using a water-cooled copper container in an atmosphere of about 1.33 Pa (hereinafter referred to as titanium material adding / dissolving step). Therefore, it is preferable to obtain a Ti—Al alloy having an Al content of less than 40% by mass.

Preferably, the melting method using the water-cooled copper container in the primary ingot manufacturing process is any one of an arc melting method, a plasma arc melting method, and an induction melting method.
Preferably, the melting method using a bottomless water-cooled copper mold in the secondary ingot manufacturing step and the divided body base ingot manufacturing step may use plasma arc or induction heating as a heat source.

According to the method for producing a Ti—Al based alloy of the present invention, a high quality and low oxygen Ti—Al based alloy is efficiently produced from a low quality titanium material containing a high concentration of oxygen with a high yield. can do.

FIG. 3 is a diagram showing a Ti—Al-based alloy manufacturing method according to the first embodiment of the present invention divided into processes. FIG. 5 is a diagram schematically showing a Ti—Al-based alloy manufacturing method according to a second embodiment of the present invention, divided into processes. It is a figure which shows the SEM image of the cross section of the secondary ingot obtained by the manufacturing method of this invention.

Hereinafter, embodiments of a method for producing a Ti—Al alloy according to the present invention will be described in detail with reference to the drawings.

First, the first embodiment will be described. As shown in FIG. 1, the Ti—Al-based alloy manufacturing method of the present embodiment has three steps of a primary ingot manufacturing process to a flux layer removing process, preferably a primary ingot manufacturing process to a flux. After the layer removal step, a titanium material addition / dissolution step is further performed to increase the oxygen content to less than 0.1% by mass from the Ti-Al alloy material W containing 0.1% by mass or more of oxygen. A high-quality Ti—Al-based alloy Z is manufactured.

Specifically, the alloy material W used in the manufacturing method of the Ti—Al-based alloy Z is a mixture of a titanium material and an aluminum material, and during the melting, deoxidation is caused by the action of aluminum contained in the aluminum material. It is to do. Further, in the manufacturing method of the present invention, CaO—CaF ₂ flux α is further added to the alloy material W to promote deoxidation. According to such a production method of the present invention, from an alloy material W containing 0.1% by mass or more of oxygen, finally, a high-grade Ti—Al based alloy Z having less than 0.1% by mass of oxygen. Can be obtained.

Hereinafter, each step of the primary ingot manufacturing process to the titanium material addition / dissolution process provided in the manufacturing method of the present invention will be described.

In the primary ingot manufacturing process, an aluminum material is added to the titanium material, the Ti-Al alloy alloy material W is deoxidized, and the deoxidized alloy material is melted as the primary ingot X. It is a process.

The alloy material W described above contains oxygen (O) in a total amount of 0.1% by mass or more and aluminum (Al) in an amount of 40% by mass or more. That is, the titanium material constituting the alloy material W includes titanium oxide (TiO ₂ ) such as low-quality and high-oxygen sponge titanium, scrap raw material, and rutile ore. The reason why low-grade titanium materials are used for the alloy material W is that these titanium materials are inexpensive and easy to procure.

In addition, the alloy material W described above has a total oxygen content of 0.1% by mass or more. For example, when the total content of oxygen in the alloy material W is less than 0.1% by mass, the content of oxygen is small and deoxidation itself is not necessary. In the present invention, the upper limit of the oxygen content is not specified, but the upper limit of the total content of oxygen actually contained in the alloy material W is considered to be about 25% by mass.

The reason why the Ti—Al-based alloy containing 40% by mass or more of Al is used for the alloy material W to be deoxidized in the primary ingot manufacturing process is as follows.

For example, according to a known ternary phase diagram of Ti—Al—O (see FIG. 5 of International Publication No. 2016/035824), the maximum amount of oxygen dissolved in a Ti—Al alloy is Ti—Al As the Al content in the alloy Z increases, the solid solution oxygen concentration tends to decrease. In other words, even in the case of the Ti-Al alloy material W produced using a low-grade titanium material, if the Al content is increased to 40% by mass or more, the alloy material W in the alloy material when deoxidation is performed. The present inventors have completed the present invention, thinking that oxygen can be lowered.

The flux α described above has a function of reducing the activity of Al ₂ O ₃ in the alloy material W by being added to the alloy material W and promoting the deoxidation reaction. That is, the flux α dissolves Al ₂ O ₃ which is a deoxidation product of the Ti—Al alloy, thereby reducing the activity of Al ₂ O ₃ which is a generated species in the deoxidation reaction, and deoxidizing the flux α. Has the effect of promoting the reaction.

The dissolution of Al ₂ O ₃ in the flux α occurs only when the flux α is melted. Therefore, if the melting point of the flux α becomes too high, the flux α does not melt and Al ₂ O ₃ does not dissolve. That is, in the CaO—CaF ₂ flux α, it is necessary to decrease the melting point of the flux α by increasing the CaF ₂ content. Therefore, in the deoxidation of the present embodiment, the content of CaF ₂ in the flux α is set to 35% by mass or more so that the melting point of the flux α is 1800K or less. Further, Ti-Al alloy Z obtained as a product so as not to be contaminated with fluorine in CaF _2, the content of CaF ₂ in the flux α is set to 95 wt% or less.

The amount of the CaO—CaF ₂ -based flux α added to the alloy material W is 3% by mass to 20% by mass with respect to the Ti—Al-based alloy Z. If the amount added to the Ti—Al-based alloy Z is less than 3% by mass, the Al ₂ O ₃ activity is not significantly reduced, and the deoxidation promoting effect is hardly obtained. If the amount added to the Ti—Al-based alloy Z is more than 20% by mass, the risk that the added flux α remains in the manufactured Ti—Al-based alloy Z increases.

Moreover, since the deoxidation performed in the primary ingot manufacturing process realizes a reduction in oxygen by increasing the Al content, the atmosphere in which the deoxidation is performed does not necessarily have to be a high vacuum. That is, it is possible to sufficiently perform deoxidation even when dissolution is performed using a water-cooled copper container prepared in an atmosphere that is not a high vacuum atmosphere, specifically, an atmosphere of 1.33 Pa or higher. is there.

Further, if deoxidation is performed in an atmosphere of 1.33 Pa or higher, the loss of volatilization of Al or Ti as in the case of deoxidation in a high vacuum atmosphere is eliminated. In other words, in the primary ingot manufacturing process, a low-oxygen Ti—Al alloy (high-grade Ti—) having a target composition is obtained while reducing the volatilization loss of Al and Ti (without substantially reducing the Ti content). Al-based alloy) can be easily manufactured.
Specifically, in the melting of the primary ingot X in the primary ingot manufacturing process, the inside of the water-cooled copper container 1 is in an atmosphere of 1.33 Pa or more, more preferably 1.33 Pa to 5.33 × 10 ⁵ Pa. It is carried out by adjusting to an atmosphere of (≈5 atm).

In addition, when melting the primary ingot X in the primary ingot manufacturing process, it is preferable to promote the deoxidation reaction by sufficiently stirring in the container 1 after adding the flux α.

For example, as such agitation, agitation using a stirrer may be considered, but after the ingot is solidified in the container 1 (mold) as in the present embodiment, the top and bottom are inverted to pull the ingot. The operation of repeating and re-dissolving may be performed a plurality of times. The stirring operation by turning the ingot (primary ingot F) upside down can be performed more preferably 2 to 5 times. In this way, if the ingot is cast several times while reversing the top and bottom, the added flux α can be reliably mixed with the alloy material to promote the deoxidation reaction, and the deoxidation is sufficiently performed. The primary ingot X can be melted.

That is, in the melting method using the water-cooled copper container 1 as in the primary ingot manufacturing process, the alloy material in the portion near the container wall of the water-cooled copper container 1 is not melted due to the effect of heat removal. Therefore, there is an undissolved (unreacted) portion in one dissolution, and a reaction for promoting deoxidation (deoxidation products Al ₂ O ₃ and CaO—CaF ₂ flux α) in the undissolved portion. Reaction) may not proceed sufficiently. Therefore, in the manufacturing method of the present embodiment, the operation of inverting the top of the primary ingot X and melting again is repeated a plurality of times. If it does in this way, the part which was not melt | dissolved by 1st melt | dissolution will melt | dissolve by the redissolving after top-and-bottom reversal, and reaction will advance between flux (alpha). If such an operation is performed a plurality of times, the molten metal in the container 1 (mold) reacts with the flux α without leaving any excess, so that the primary ingot is sufficiently deoxidized even if the water-cooled copper container 1 is used. X can be melted.

In the primary ingot X subjected to the above-described primary ingot manufacturing process, Al ₂ O ₃ generated by the deoxidation reaction is included as the flux α. In the secondary ingot manufacturing process, the flux α is ingot (secondary ingot Y) so that Al ₂ O ₃ generated in the primary ingot manufacturing process is easily removed mechanically in the flux layer removing process described later. Are gathered biased to a part (in this embodiment, the outer peripheral side). The ingot in which the fluxes are biased in this way is the secondary ingot Y.

Specifically, in the secondary ingot manufacturing process, the primary ingot X is continuously drawn out downward while being melted by a melting method using a bottomless water-cooled copper mold 2 in an atmosphere of 1.33 Pa or higher. The ingot Y is obtained. As the melting method using the water-cooled copper mold 2, a method of melting using a plasma arc or induction heating as a heat source can be used, but a method of melting using a plasma arc as a heat source is preferably used. On the surface of the molten metal supplied to the inside of the water-cooled copper mold 2, a flux α in which Al ₂ O ₃ is dissolved floats. If a plasma arc is used as a heat source, the flux α is generated by the arc sprayed on the surface. Coagulation is performed in a state of being concentrated in the vicinity of the inner peripheral surface and being concentrated in the vicinity. As a result, in the secondary ingot Y that is melted in the secondary ingot manufacturing process, the flux α is biased to exist on the outer peripheral side of the secondary ingot Y that is drawn downward. In this way, if the secondary ingot Y is present with the flux α being biased on the outer peripheral side, the surface adhering flux layer β formed on the outer peripheral surface of the secondary ingot Y is shot blasted or ground in the flux layer removing process. If the mechanical means 3 is used, the Al ₂ O ₃ together with the flux can be removed.

The flux layer removing step is a step of scraping off the surface-adhered flux layer β formed on the outer peripheral surface of the secondary ingot in the secondary ingot manufacturing step by mechanical means 3 such as shot blasting or grinding. By performing this flux layer removal step, the oxygen concentration of the secondary ingot Y can be lowered as a whole.

Ti-Al alloy Z obtained through the flux layer removing step from the primary ingot manufacturing process described above, the flux biased to the outer periphery surface of the secondary ingot Y in the secondary ingot manufacturing process α, Al ₂ O _3, or the The surface-attached flux layer β is removed by mechanical means 3 such as shot blasting or grinding in the flux layer removing process, so that the oxygen content contained in the Ti—Al-based alloy Z is greatly reduced. Oxygen initially contained in the material W can be reliably deoxidized and reduced. That is, according to the manufacturing method of the Ti—Al-based alloy Z of the present embodiment, the high-quality, that is, the low-oxygen Ti—Al-based alloy Z is efficiently obtained from low-grade titanium containing a high concentration of oxygen with high yield. Can be manufactured.

Note that, in the manufacturing method of the Ti—Al based alloy Z of the present embodiment, the oxygen content contained in the Ti—Al based alloy Z is totaled by setting the Al content in the alloy material W to 40 mass% or more. Therefore, the Ti-Al alloy Z to be manufactured necessarily has an Al content of 40% by mass or more. However, when the obtained Ti—Al-based alloy Z is used, there is a desire to reduce the Al content to less than 40% by mass.

In such a case, in addition to the primary ingot manufacturing process to the flux layer removing process described above, the titanium material addition / dissolution process described below may be performed.

That is, the titanium material addition / dissolution step is performed by adding the titanium material V to the secondary ingot Y and dissolving it by a melting method using a water-cooled copper mold 4 (water-cooled copper container) in an atmosphere of 1.33 Pa or more. A Ti—Al based alloy Z2 having an Al content of less than 40% by mass is obtained. The melting method shown in the figure uses a water-cooled copper container, but the melting method used in this titanium material addition / dissolution step is a melting method other than water-cooled copper induction melting (CCIM), such as a vacuum arc melting method. (VAR) or vacuum induction melting (VIM) may be used.

Specifically, the titanium material V added to the secondary ingot Y in the titanium material addition / melting step is a Ti-Al alloy Z2 having an Al content of less than 40% by mass after the titanium material addition / melting step. In the case of obtaining the titanium material V, the Al content is preferably less than 40% by mass. For example, if a titanium material V having an Al content of less than 40% by mass, such as pure Ti that does not contain aluminum as an impurity, is added, the Al content contained in the secondary ingot Y is reduced by dilution. A Ti—Al-based alloy Z2 whose amount is less than 40% by mass can be obtained.

Since the titanium material V added in the titanium material addition / dissolution process varies depending on the required quality of the Ti—Al alloy Z2 to be manufactured, components other than aluminum in the titanium material V (Sn, V, Mn The concentration of such metals other than aluminum cannot be specified.
However, if the titanium material addition / dissolution process is performed in addition to the primary ingot manufacturing process to the flux layer removal process described above, a Ti-Al alloy Z2 that meets the required quality can be obtained for the composition other than oxygen and aluminum. Thus, the convenience of the production method of the present invention can be further enhanced.

Next, a second embodiment will be described.
As shown in FIG. 2, the manufacturing method of the Ti—Al-based alloy 101 according to the present embodiment has three steps of a raw material dividing step to a flux layer removing step, preferably after the raw material dividing step to the flux layer removing step. Further, a titanium material addition / dissolution step is performed to obtain a high-grade Ti—Al in which the oxygen content is less than 0.1% by mass from the alloy material of the Ti—Al alloy 101 containing 0.1% by mass or more of oxygen. The system alloy 101 is manufactured.

Specifically, the alloy material used in the manufacturing method of the Ti—Al alloy 101 is a mixture of a titanium material and an aluminum material. When the melting raw material 102 mixed with aluminum is melted in the divided body base ingot manufacturing process in this way, the aluminum reacts with oxygen in the alloy material to perform deoxidation. In the production method of the present invention, CaO—CaF ₂ -based flux 103 is added to the alloy material for the purpose of promoting deoxidation in the raw material dividing step. When such a flux 103 is added in the raw material dividing step, deoxidation in the divided base ingot manufacturing step is further promoted, and oxygen is finally reduced from an alloy material containing 0.1% by mass or more of oxygen. It is possible to obtain a high-grade Ti—Al-based alloy 101 of less than 1 mass%.

In the raw material dividing step, the melted raw material 102 to which the flux 103 is added is divided into a plurality of pieces to form divided bodies. In the divided body base ingot manufacturing process, the lowering operation is performed on all the divided bodies following the melting operation of the divided body of the melting raw material 102, and non-metallic inclusions such as Al ₂ O ₃ are added to the flux 103. In addition to the transition, the flux 103 to which the non-metallic inclusions are transferred can be unevenly distributed (localized) on the outer peripheral surface of the ingot. The non-metallic inclusions and the flux 103 that are unevenly distributed in this way are mechanically removed in the flux layer removing step, or preferably the component adjustment is further performed in the titanium material adding / dissolving step, so that the Ti—Al of the present invention A system alloy 101 is manufactured.

Hereinafter, each step of the raw material dividing step to the titanium material addition / dissolution step provided in the production method of the present invention will be described.

In the raw material dividing step, the flux 103 is added to the alloy material of the Ti—Al-based alloy 101 to produce the molten raw material 102, the produced molten raw material 102 is divided into n pieces, and the first divided body 141˜ The n-th divided body is formed. This dividing operation of the melting raw material 102 is a feature of the manufacturing method of the present invention.

Specifically, the alloy material of the Ti—Al based alloy 101 used for the melting raw material 102 is made of a titanium material and an aluminum material, and the total amount of oxygen is 0.1 mass% or more and Al is 40 mass%. Contains above. Further, the flux 103 blended in the alloy material is a CaO—CaF ₂ -based flux 103 in which 35 to 95 mass% of calcium fluoride is blended with calcium oxide. The alloy material described above is blended with the flux 103 in an amount of 3 to 20% by mass to form the melting raw material 102 of this embodiment.

Incidentally, the titanium material constituting the above-mentioned alloy material is one containing a sponge titanium containing much oxygen in low-grade scrap material, titanium oxide such as rutile ore (TiO _2). The reason why low-grade titanium materials are used in this way is that these titanium materials are inexpensive and easy to procure.

Further, the above-described alloy material has a total oxygen content of 0.1% by mass or more. For example, when the total content of oxygen in the alloy material is less than 0.1% by mass, the content of oxygen is small and deoxidation itself is not necessary. In the present invention, the upper limit of the oxygen content is not specified, but the upper limit of the total content of oxygen actually contained in the alloy material is considered to be about 25% by mass.

The reason why the Ti—Al alloy 101 containing 40% by mass or more of Al is used as the alloy material used for the melting raw material 102 in the raw material dividing step is based on the following reason.
For example, according to a known ternary phase diagram of Ti—Al—O (see FIG. 5 of International Publication 2016/035824), the maximum amount of oxygen dissolved in the Ti—Al alloy 101 is Ti— As the Al content in the Al-based alloy 101 is increased, the dissolved oxygen concentration tends to decrease. In other words, even the melting raw material 102 containing the Ti—Al alloy 101 produced using a low-grade titanium material can be removed in the divided base ingot manufacturing process if the Al content is increased to 40% by mass or more. The inventors have thought that oxygen in the alloy material can be lowered when acid is performed, and the present inventors have completed the present invention.

The flux 103 described above has the function of reducing the activity of Al ₂ O ₃ in the melting raw material 102 by being added to the melting raw material 102 and promoting the deoxidation reaction in the divided body ingot manufacturing process described later. is doing. That is, the flux 103 dissolves Al ₂ O ₃ which is a deoxidation product of the Ti—Al-based alloy 101, thereby reducing the activity of Al ₂ O ₃ which is a generated species in the deoxidation reaction. Has the effect of promoting acid reaction.

The dissolution of Al ₂ O _{3 in} the flux 103 occurs only when the flux 3 is melted. Therefore, if the melting point of the flux 103 becomes too high, the flux 103 does not melt and Al ₂ O ₃ does not dissolve. That is, in the case of the CaO—CaF ₂ based flux 103, it is necessary to decrease the melting point of the flux 103 itself by increasing the content of CaF ₂ having a low melting point. Specifically, in the deoxidation of the present embodiment, the content of CaF ₂ in the flux 103 is set to 35% by mass or more so that the melting point of the flux 103 is 1800K or less. Moreover, so as not to Ti-Al alloy 101 obtained as a product after the flux layer removing step or titanium material adding and dissolving process is contaminated with fluorine in CaF _2, the content of CaF ₂ in the flux 103 It is 95 mass% or less.

The addition amount of the CaO—CaF ₂ -based flux 103 to the melting raw material 102 is 3% by mass to 20% by mass with respect to the Ti—Al-based alloy 101 as a product. If the addition amount relative to Ti-Al alloy 101 is less than 3 wt%, _Al 2 _{O 3} does not occur reduction in the activity of so much, no deoxidation promoting effect is hardly obtained. If the amount added to the Ti—Al based alloy 101 is more than 20 mass%, the risk that the added flux 103 remains in the manufactured Ti—Al based alloy 101 increases.

In this way, in the raw material dividing step, the melting raw material 102 is first prepared by blending the flux 103 with the alloy material.

By the way, the melting raw material 102 in which the flux 103 is mixed with the alloy material of the Ti—Al alloy 101 in the above-described raw material dividing step is charged into the water-cooled copper crucible 105 and melted (the solidification method in the crucible is performed). Non-metallic inclusions such as Al ₂ O ₃ cannot be sufficiently removed. In order to sufficiently remove the non-metallic inclusions, it is necessary to perform an operation of a divided body base ingot manufacturing process as described below.

Specifically, when the above-described dissolving raw material 102 is prepared, the prepared dissolving raw material 102 is divided into n pieces to form the first divided body 141 to the n-th divided body. “N”, which is the number of divisions of the melting raw material 102, is an integer of 2 or more, and the melting raw material 102 is divided into a plurality of divided bodies in the raw material dividing step.

Further, when the melting raw material 102 is divided in the raw material dividing step, the weight of each divided body (the first divided body 141 to the nth divided body) is the maximum with respect to the final target ingot weight at the end of casting. The melted raw material 2 after adjustment is divided into n so as to be 4/5 or less. For example, as shown in FIG. 2, when the final target ingot weight is 100 ton and the melting raw material 2 is divided into three, all of the first divided body 141 to the third divided body 143 are 80 ton or less. Need to be divided like so. Industrially, the divided body is preferably equally divided (in this case, 33.3 ton), but the present invention is not limited to equally dividing the divided body.

If such a division is performed, none of the first divided body 141 to the n-th divided body obtained in the raw material dividing step will exceed 4/5 of the final target ingot weight at the end of casting. Heat removal from the bottom 107 of the copper crucible 105 can be suppressed, and the deoxidation reaction can be sufficiently promoted.

More specifically, as described above, the raw material weight of each divided body after dividing the molten raw material 102 is divided so as to be 4/5 or less of the whole at the maximum with respect to the final ingot weight. That is, at least two melting operations and two lowering operations (partition body charging / dissolution → lowering → partition body charging / dissolution → lowering) are required. This is because the portion close to the water-cooled copper crucible 105 at the bottom 107 is strongly cooled by only one melting operation, and solidification proceeds before the charged flux 103 is sufficiently melted. Therefore, Al ₂ O ₃ It is difficult for non-metallic inclusions such as these to react with the flux 103. In this regard, since the heat removal from the bottom 107 is suppressed in the second and subsequent melting operations, the flux 103 and the non-metallic inclusions sufficiently react with each other during the second and subsequent melting, thereby promoting deoxidation. To do.

In addition, if the weight of each divided body is more than 4/5 of the final target weight, the separation efficiency between the metal and the flux 103 can be lowered even if the second and subsequent melting operations are performed. There is sex. For example, when the weight of the first divided body 141 exceeds 4/5 of the final target weight, the non-metallic inclusions and the flux can be dissolved even if the amount less than the remaining 1 / V is dissolved in the second and subsequent dissolutions. Reaction with 103 is less likely to occur. For this reason, it is desirable to divide the divided body into a maximum of 4/5 or less, preferably 2/3 or less of the whole, more preferably I / 2 or less of the whole.

In the present embodiment shown in FIG. 1, the present invention has been described by giving an example in which the dissolved raw material 102 is divided into three parts and deoxidized in the raw material dividing step, but the number of divisions is five. Even if it is 11 divisions, there is no problem.

In the divided body base ingot manufacturing process, the first divided body 141 of the melted raw material 102 divided in the raw material dividing process is charged into a water-cooled copper crucible 105 (bottomed water-cooled copper crucible 105) to be inactive at 1.33 Pa or more. An operation of melting under a gas atmosphere and pulling down the water-cooled copper crucible 105 at a speed of 15 mm or less per minute is performed, and then the second divided body 142 of the melted raw material 102 divided in the raw material dividing step is bottomed out. 105 is dissolved in an inert gas atmosphere of 1.33 Pa or higher, and the water-cooled copper crucible 105 is lowered downward at a speed of 15 mm or less per minute, and thereafter the same operation is performed up to the n-th divided body. The ingot is formed by repeating.

In other words, the divided body base ingot manufacturing process includes a melting operation in which a divided body of the melting raw material 102 is charged into a water-cooled copper crucible 105 and melted in an inert gas atmosphere of 1.33 Pa or more, and this melting operation is followed. Then, the operation of continuously lowering the water-cooled copper crucible 105 downward at a speed of 15 mm / min or less is performed as “basic operation”. And this basic operation is performed once in order about each of the 1st division body 141, the 2nd division body 142, ..., and the nth division body.
The reason why the inert gas atmosphere is 1.33 Pa or more is that no volatilization loss of Al or Ti occurs as in the case of melting in a high vacuum atmosphere. More preferably, it is dissolved in an inert gas atmosphere of 1.33 Pa to 5.33 × 10 ⁵ Pa (≈5 atm).

In the case of the present embodiment, since the melting raw material 102 is divided into three, the melting operation of the first divided body 141 → the lowering operation of the first divided body 141 → the melting operation of the second divided body 142 → the second The divided body base ingot manufacturing process proceeds by processing the melting raw material 102 in the order of the lowering operation of the divided body 142, the melting operation of the third divided body 143, and the lowering operation of the third divided body 143.

Next, the melting operation and the lowering operation performed on each divided body of the melting raw material 102 in the divided body base ingot manufacturing process will be described in detail.

In the divided body base ingot manufacturing process, each divided body of the melting raw material 102 is charged into a water-cooled copper crucible 105 (water-cooled copper mold) prepared in an inert gas atmosphere of 1.33 Pa or more, and water-cooled. The ingot is cast by melting each divided body of the melting raw material 102 in the copper crucible 105 using a plasma arc or induction heating as a heat source. In addition, when the divided body of the melting raw material 102 is melted using the water-cooled copper crucible 105, the melting is preferably performed using induction heating as a heat source. Generally, when metals containing non-metallic inclusions such as oxides are melted by induction heating, the non-metallic inclusions gather outside the molten metal due to the difference in electrical conductivity between the non-metallic inclusions and the metal. It is known. That is, the flux 103 in which the Al ₂ O ₃ in the molten metal supplied into the water-cooled copper crucible 105 is concentrated in the vicinity of the inner peripheral surface of the mold due to induction heating, and solidification is performed in the state of being concentrated. As a result, the surface-attached flux layer 108 in which the flux 103 is biased and present on the outer peripheral side of the ingot drawn downward is formed in the ingot melted in the divided body base ingot manufacturing process. In the case of an ingot in which the surface-attached flux layer 108 exists on the outer peripheral side in this way, the surface-attached flux layer 108 can be scraped off by mechanical means such as shot blasting or grinding in the flux layer removing process. This is because non-metallic inclusions such as Al ₂ O ₃ can be removed.
Further, the pulling-down operation performed following the melting operation of the divided body of the melting raw material 102 in the divided body base ingot manufacturing process is the surface adhesion formed on the surface of the ingot by melting the flux 103 by the above-described melting operation. The flux layer 108 is unevenly distributed between the mold and the ingot. Specifically, the above-described water-cooled copper crucible 105 has a structure in which a cylindrical crucible body 106 that opens both upward and downward and a bottom portion 107 that is disposed on the bottom side of the crucible body 106 are combined. It has become. The bottom 107 of the water-cooled copper crucible 105 is attached to the crucible main body 106 so as to be movable in the vertical direction. When the bottom 107 is lowered with respect to the crucible main body 106, the cast placed on the upper side of the bottom 107 is performed. The lump can also be lowered. In the divided body base ingot manufacturing process, by performing such a pulling-down operation, the surface adhering flux layer 108 is unevenly distributed between the outer periphery side of the ingot, in other words, between the mold and the ingot.

In the lowering operation of this embodiment, the ingot lowering speed, in other words, the lowering speed of the bottom 107 of the water-cooled copper crucible 105 is set to 15 mm / min or less, preferably 10 mm / min or less. If the ingot lowering speed exceeds 15 mm / min, the surface-adhered flux layer 108 formed on the outer peripheral surface of the ingot in the above-described divided body base ingot manufacturing process is broken, and the surface-adhered flux layer 108 is used as a mold. This is because it is difficult to make it unevenly distributed between the steel and the ingot.

The one that performs the above-described dissolving operation and pulling-down operation once at a time is the “basic operation” for a certain divided body. This “basic operation” is performed once for each of the first divided body 141, the second divided body 142,.

For example, in the case of the divided body base ingot manufacturing process of the illustrated example, the melting raw material 102 is divided into three, and the first divided body 141, the second divided body 142, and the third divided body 143 exist, Melting operation of first divided body 141 → Lowering operation of first divided body 141 → Melting operation of second divided body 142 → Lowering operation of second divided body 142 → Melting operation of third divided body 143 → Third divided body 143 In the end, a cylindrical ingot that is long in the vertical direction is melted (cast) in the divided base ingot manufacturing process.

The outer peripheral surface of the ingot was cast with the above-mentioned divided body based ingot manufacturing process and surface deposition flux layer 108 solidified in a state where the flux 103 is biased is formed on the surface adhering flux layer 108 Al ₂ Non-metallic inclusions such as O ₃ are also contained at a high concentration. Therefore, if the surface adhering flux layer 108 formed on the outer peripheral surface of the ingot is scraped by mechanical means such as shot blasting or grinding in the flux layer removing step, the non-metallic inclusions such as Al ₂ O ₃ together with the flux 103 The oxygen concentration contained in the ingot can be lowered as a whole.

The Ti—Al-based alloy 101 obtained from the raw material dividing step through the flux layer removing step has the surface-attached flux layer 108 formed on the outer peripheral surface of the ingot in the divided body base ingot manufacturing step. Since it is removed by mechanical means such as shot blasting and grinding in the process, the oxygen content contained in the Ti-Al alloy 101 is greatly reduced, and the oxygen originally contained in the alloy material is reliably deoxidized. Has been reduced. That is, according to the manufacturing method of the Ti—Al based alloy 101 of the present embodiment, the high quality, that is, the low oxygen Ti—Al based alloy 101 is efficiently produced from the low quality titanium containing a high concentration of oxygen with a high yield. Can be manufactured.

Note that, in the manufacturing method of the Ti—Al based alloy 101 of the present embodiment, the oxygen content contained in the Ti—Al based alloy 101 is totaled by setting the Al content in the alloy material to 40% by mass or more. Since the Ti content is less than 0.1% by mass, the produced Ti—Al-based alloy 101 inevitably has an Al content of 40% by mass or more. However, when the obtained Ti—Al-based alloy 101 is used, there is a desire to reduce the Al content to less than 40% by mass.

In such a case, in addition to the above-described raw material dividing step to flux layer removing step, the titanium material addition / dissolution step described below may be performed.

That is, in the titanium material addition / dissolution step, the titanium content is added to the ingot and melted by a melting method using a water-cooled copper mold (water-cooled copper container 109) in an atmosphere of 1.33 Pa or higher, so that the Al content is increased. A Ti—Al alloy 101 of less than 40% by mass is obtained. The melting method illustrated in FIG. 2 uses a water-cooled copper container, but the melting method used in this titanium material addition / dissolution step is a melting method other than water-cooled copper induction melting (CCIM), such as a vacuum arc. A melting method (VAR) or vacuum induction melting (VIM) may be used.
Specifically, the titanium material added to the ingot in the titanium material addition / melting step is to obtain a Ti—Al alloy 101 having an Al content of less than 40 mass% after the titanium material addition / melting step. The titanium content is preferably less than 40% by mass. For example, if a titanium material with an Al content of less than 40% by mass, such as pure Ti that does not contain aluminum as an impurity, is added, the Al content contained in the ingot is reduced by dilution, so the Al content is 40% by mass. A Ti—Al alloy 101 that is less than 1% can be obtained.

The titanium material added in the titanium material addition / dissolution step varies depending on the required quality of the Ti—Al alloy 101 to be manufactured. Therefore, components other than aluminum (such as Sn, V, Mn, etc.) in the titanium material. The concentration of the metal other than aluminum cannot be specified and can be arbitrarily changed.

In the manufacturing method of the present embodiment, the ratio (H / D) between the final ingot height H (final target ingot height) and the ingot diameter D is not particularly limited. From the viewpoint, it is preferably 1 or more.

If the titanium material addition / dissolution step is performed in addition to the above-described raw material splitting step to flux layer removal step, the Ti—Al alloy 101 that matches the required quality can be obtained for the composition other than oxygen and aluminum. The convenience of the manufacturing method can be further enhanced.

Next, the effects of the method for producing a Ti—Al alloy of the present invention will be described in detail using comparative examples and examples.

(Example according to the first embodiment)
In Examples and Comparative Examples, CaO—CaF ₂ flux α is added to an alloy material W prepared by mixing an aluminum material with a titanium material, and O (oxygen) contained in the alloy material W is added. Deoxidized.

In Example 1, the alloy material W containing 40% by mass of Al and 0.8% by mass of O was processed from the primary ingot manufacturing process to the titanium material adding / dissolving process. Is an alloy material W containing 50% by mass of Al and 0.8% by mass of O as compared with Example 1 and subjected to the treatment from the primary ingot manufacturing process to the titanium material addition / dissolution process. is there.

Moreover, the comparative example 1 and the comparative example 2 do not perform a secondary ingot manufacturing process and a flux layer removal process after a primary ingot manufacturing process among four processes which comprise the manufacturing method of this invention, The titanium material is directly added and dissolved. In Comparative Example 1, the inclusions that were confirmed to be generated after the primary ingot manufacturing step were left without being removed, and Comparative Example 2 was obtained by removing inclusions as much as possible.

Further, the primary ingot manufacturing process, scrap Ti, titanium oxide _(TiO 2), pure Al, the CaO-CaF ₂ as a raw material by a plasma arc melting method, intermediate material (Ti-40, 50 wt% Al-0 .8 mass% O), the secondary ingot manufacturing step, the ingot manufactured in the primary ingot manufacturing step is remelted by the plasma arc drawing melting method, and the flux layer removing step is The step of mechanically removing the flux layer (containing Al ₂ O ₃ ) adhering to the ingot surface after the secondary ingot manufacturing step and the titanium material addition / dissolution step are the primary ingot manufacturing step (Comparative Example 1). Comparative Example 2) or Ti—Al ingot produced in the primary ingot production process + secondary ingot production process + flux layer removal process (Examples 1 and 2), pure Ti (O: 0. In a plasma arc melting method, A step of melting the -30 wt% Al ingot.

"Comparative Example 1"
A titanium material such as titanium oxide (TiO ₂ ) contained in scrap titanium and rutile ore is mixed with pure Al aluminum material, and Ti—40% by mass of Al and 0.8% by mass of O in Ti— An alloy material of an Al alloy was prepared. Further, a CaO—CaF ₂ flux was added to this alloy material so that the addition amount was 5% with respect to the total weight of the Ti—Al alloy. Thus, the alloy material to which the flux was added was cast in a 100 kW plasma arc furnace, and the primary ingot was melted while performing deoxidation.
Note that the flux of CaO-CaF ₂ described above, CaO ratio of CaO and CaF ₂ are in a weight ratio: in which is an 8: _CaF 2 = 2. Further, the plasma arc furnace used for melting the primary ingot was one using Ar as the plasma gas, and the plasma gas was supplied into the furnace at a pressure of 1.20 × 10 ⁵ Pa to perform melting. Is.

In Comparative Example 1, a Ti-Al alloy is melted by directly adding and melting a titanium material after the primary ingot manufacturing process. That is, in Comparative Example 1, the primary ingot is not subjected to the secondary ingot manufacturing process in which the primary ingot is continuously drawn while being melted by a melting method using a bottomless water-cooled copper mold. internal and remains from entrapment as Al ₂ O ₃ or flux, not performed the flux layer removing step.

The ingot after the primary ingot manufacturing process was cut, the cut surface was observed with an SEM, and the internal structure of the ingot was observed. Result of section observation by SEM, in the interior of the ingot in Comparative Example 1, with portions oxide inclusions such as flux, Al ₂ O ^3, or the there is confirmed, interposed such flux, Al ₂ O _3, or the Sites where no objects exist were also confirmed. When the oxygen concentration was measured by the inert gas melting method for both the portion where the inclusion was confirmed and the portion where the inclusion was not confirmed, the inclusion was confirmed as shown in Table 1. At the position where the oxygen concentration was 1.82% by mass, and at the position where no inclusion was confirmed, the oxygen concentration was 0.24% by mass. From this, it can be seen that the inclusions confirmed by SEM observation are inclusions such as flux and Al ₂ O ₃ .

In addition, a titanium material (pure Ti) containing 0.05% by mass of oxygen is added to the ingot after the primary ingot manufacturing process, so that the Al content becomes 30% by mass. As a result, a Ti—Al alloy having an oxygen concentration of 0.79% by mass was obtained. When the cross-sectional observation of the Ti—Al based alloy after the titanium material addition / melting step was performed by SEM, the oxide inclusions observed after the primary ingot manufacturing step were not confirmed.

From this, as shown in Comparative Example 1, pure Ti (0.05% by mass of O is contained in the titanium material addition / dissolution step with respect to the alloy material in which oxide inclusions remain after the flux layer removal step. When the titanium material is added, oxides such as Al ₂ O ₃ are decomposed and redissolved in the molten metal, and the oxygen concentration is increased.

"Comparative Example 2"
In contrast to Comparative Example 1 described above, Comparative Example 2 is obtained by mechanically removing the Ti—Al alloy region containing oxide inclusions that was confirmed after the primary ingot manufacturing process. That is, since oxygen is removed from the Ti—Al based alloy by removing inclusions, the oxygen content of Comparative Example 2 is comparative when the Al content is 30% by mass. The oxygen content is 0.21% by mass, which is smaller than in Example 1. However, when removing the oxide inclusions, not only the inclusions contained in the ingot but also the metal (Ti—Al alloy) is lost. Therefore, the “intermediate material use amount” indicating how much of the alloy material has become a Ti—Al alloy, in other words, “yield” is 50%, which is about half of Comparative Example 1. Yes.

"Example 1"
In contrast to Comparative Example 1 and Comparative Example 2 described above, Example 1 is prepared by mixing the same raw materials as Comparative Example 1 and Comparative Example 2 to adjust the alloy material W, and further adding CaO—CaF ₂ flux to the alloy material W. The primary ingot X is melted by adding α (CaO: CaF ₂ = 2: 8 weight ratio). The processing conditions for melting the primary ingot X are also the same as in the comparative example, using a 100 kW plasma arc furnace and melting at a pressure of 1.20 × 10 ⁵ Pa.

Example 1 differs from the comparative example in that the upside down and remelting, which was not the comparative example, is repeated three times.

That is, as in Comparative Example 1 and Comparative Example 2, after the primary ingot manufacturing process, each of the parts (total) for both the part where the inclusion is confirmed and the part where the inclusion is not confirmed. When the oxygen concentration is analyzed by an inert gas melting method, the oxygen concentration is 0.19% by mass for the site where the inclusion is not confirmed, and the site where the inclusion is confirmed (the site where the inclusion remains) The oxygen concentration was 1.90% by mass. This is because the top and bottom reversal and remelting were repeated three times in the primary ingot manufacturing process, and the reaction of Al ₂ O ₃ and CaO—CaF ₂ flux α progressed further, and the deoxidation reaction was promoted. This is presumed to be due to this.

For the primary ingot X melted in the primary ingot manufacturing step in this way, the secondary ingot Y is melted while being drawn downward by a melting method using a plasma arc as a heat source. did.
As shown in FIG. 3, CaO—CaF ₂ -based flux α containing Al ₂ O ₃ was discharged and adhered to the surface of the secondary ingot Y. On the other hand, there are almost no oxide inclusions inside the secondary ingot Y, and most of the inclusions that were unevenly present inside are discharged to the ingot surface. I understood.

The secondary ingot Y was subjected to shot blasting (mechanical means 3) in the flux layer removing step to remove the flux layer β on the surface of the secondary ingot Y. To the ingot from which the flux layer β has been removed, pure Ti (oxygen concentration 0.05 mass%) is further added as a titanium material addition / dissolution step, and Ti-30 mass% Al alloy Z2 is melted to reduce the oxygen concentration. analyzed.

As a result of analysis, it was found that 0.16% by mass of oxygen was contained in the Ti—Al-based alloy Z2 after the titanium material addition / dissolution step. Since almost no oxide inclusions were present in the internal structure of the alloy, it can be understood that the oxygen concentration did not increase due to remelting of the flux as in Comparative Example 1. Further, since only the flux is efficiently removed in the flux layer removing step, the yield is not reduced as in Comparative Example 2. Therefore, if deoxidation is performed according to the procedure as in Example 1, even if a low-grade titanium raw material is used, a high-grade, low-oxygen Ti—Al-based alloy that results in an Al content of less than 40% by mass. It is determined that Z2 can be manufactured.

"Example 2"
In addition, the knowledge as obtained in Example 1 described above can also be obtained for the alloy material W of Example 2 in which the Al content is 50 mass% higher than in Example 1.

That is, as shown in Table 1, even when the composition of the alloy material W is Ti-50 mass% Al-0.8 mass% O, if the Ti-30 mass% Al alloy is melted, the oxygen concentration is reduced. It is possible to produce a 0.07 mass% Ti—Al-based alloy Z2.

(Example according to the second embodiment)
In Examples and Comparative Examples, CaO—CaF ₂ flux 103 is added to an alloy material prepared by mixing an aluminum material with a titanium material to deoxidize O (oxygen) contained in the alloy material. It is a thing.

In Example 1, the alloy material containing 40% by mass of Al and 0.8% by mass of O was processed from the raw material dividing step to the titanium material adding / dissolving step. In Example 2, the alloy material containing 60% by mass of Al and 0.8% by mass of O was processed from the raw material dividing step to the titanium material adding / dissolving step. In Example 3, the alloy material containing 45% by mass of Al and 0.8% by mass of O was subjected to the raw material dividing step to the titanium material adding / dissolving step. In Example 4, the alloy material containing 52% by mass of Al and 0.8% by mass of O is subjected to the raw material dividing step to the titanium material adding / dissolving step.

The number of divisions of the melting raw material 2 in Examples 1 to 4 is “11”, and one melting operation and one time are performed for each of the first divided body 141 to the eleventh divided body (not shown). The "basic operation" consists of a pull-down operation.

Further, Comparative Example 1 uses an alloy material having the same composition as Example 1, but the melting raw material 102 is not divided during the raw material dividing step, and only the melting operation is performed in the divided body base ingot manufacturing step. The ingot is obtained by performing. In Comparative Example 1, the obtained ingot was further subjected to a titanium material addition / dissolution step to obtain a Ti-30Al ingot.

Furthermore, Comparative Example 2 was obtained by performing the same process as Comparative Example 1 to obtain an ingot, and the titanium material addition / dissolution step was performed using only a specific part of the obtained ingot.

Further, in Comparative Example 3, as in Example 1, the alloy material containing 40% by mass of Al and 0.8% by mass of O was processed from the raw material dividing step to the titanium material adding / dissolving step. . Comparative Example 3 is different from Example 1 in that the flux 103 is not blended with the melting raw material 102.

Specifically, the above-described raw material dividing step to titanium material addition / dissolution step were performed under the following conditions.

First, in the raw material dividing step, scrap Ti, titanium oxide (TiO ₂ ), and pure Al are used as alloy materials. For Comparative Example 1, Comparative Example 2, and Example 1, a CaO—CaF ₂ flux 103 is used as a Ti—Al system. 10% of the weight of the alloy 101 was blended, and in Comparative Example 3, the melting raw material 102 was produced without blending the flux 103. The flux 103 used in these comparative examples and examples is a flux 103 (CaO—CaF ₂ -based flux 103) containing CaO and CaF ₂ so that the CaO: CaF ₂ = 2: 8 weight ratio.

Further, in the split body base ingot manufacturing process, the melted raw material 102 prepared in the raw material splitting process is charged into a water-cooled copper crucible 105 (inner diameter 80 mm) having no bottom, and argon as an inert gas is introduced. It melt | dissolved using the induction dissolving apparatus on the conditions made into the pressure of 6.6 * 10 < ⁴ > Pa under Ar atmosphere used. In the divided body base ingot manufacturing process of Examples 1 to 4 and Comparative Example 3, the melting raw material 102 is divided into 11 parts in the raw material dividing process, and the first divided body 141 to the 11th divided body (not shown) are preliminarily formed. After the formation, the dissolution operation and the pull-down operation were performed once for each of the divided bodies, and the dissolution raw material 102 was dissolved to proceed with deoxidation. Moreover, about the comparative example 1 and the comparative example 2, as above-mentioned, the division body base ingot manufacturing process itself is not implemented.

For the ingot cast in the divided body base ingot manufacturing process in this way, the inside of the ingot after melting was observed with an SEM.

In addition, in the flux layer removing step, the surface-attached flux layer adhered to the surface of the ingot by performing shot blasting as a mechanical means on the surface of the ingot with respect to the ingot cast in the divided body base ingot manufacturing step 108 was removed. About the ingot from which the surface adhesion flux layer 108 was removed in the flux layer removing step, the oxygen concentration contained in the ingot was analyzed by an inert gas melting method.

Further, in the titanium material addition / melting step, pure Ti having an oxygen concentration of 0.05 mass% is added to the ingot from which the surface adhering flux layer 108 has been removed in the flux layer removing step using a plasma arc melting furnace. Ti-30 mass% Al alloy was melted. As for the ingot of the Ti-30 mass% Al alloy produced in the titanium material addition / dissolution step, the oxygen concentration was analyzed by an inert gas melting method in the same manner as the ingot after the flux layer removal step.

Table 2 shows the analysis results of Examples and Comparative Examples.

"Comparative Example 1"
In Comparative Example 1, as described above, the melting raw material 102 is not divided in the raw material dividing step, and only the melting operation without the pulling-down operation is performed on the molten raw material 102 that is not divided in the divided body base ingot manufacturing process. Thus, an ingot is obtained.

When the ingot obtained in Comparative Example 1 was taken out after the divided body base ingot manufacturing process and visually observed, a surface adhesion flux layer 108 was formed on the surface of the ingot. Moreover, in the comparative example 1, the flux 103 currently wound inside the alloy structure was also confirmed visually.

Moreover, about the ingot of "Comparative example 1," the SEM observation with respect to the inside of an ingot is also performed. Was observed by SEM, the inner ingot, a portion as Al ₂ O ₃ and flux 103 does not exist, and the site where the flux 103 is present, it was confirmed that a mixture.

Further, as a result of analyzing the oxygen concentration of the obtained ingot by an inert gas melting method, oxygen was 0.50% by mass in a site where no inclusion was present, and in a site where an inclusion was present 1.16% by mass of oxygen was detected.

Further, the ingot described above is melted using a plasma arc melting furnace in the titanium material addition / melting step, and pure Ti (oxygen concentration 0.05 mass%) is added to the ingot to obtain a Ti-30 mass% Al alloy. The oxygen concentration of the resulting Ti-30 mass% Al alloy ingot was analyzed by an inert gas melting method. As a result of the analysis, 0.79% by mass of oxygen was detected. Furthermore, when the inside of an ingot of Ti-30 mass% Al alloy was observed with an SEM, the presence of oxide inclusions such as Al ₂ O ₃ was not confirmed.

From the results of the visual inspection and SEM observation described above, in Comparative Example 1, the flux 103 and oxide inclusions (non-metallic inclusions) remain in the obtained ingot, and the flux 103 and oxide inclusions are present. It is judged that the inside of the ingot remains, and it can be seen that oxygen in the Ti—Al alloy 101 cannot be sufficiently reduced.

Further, when the oxygen concentration in the Ti—Al based alloy 101 of the comparative example was measured, oxygen greatly exceeding 0.1 mass% was detected regardless of the presence or absence of inclusions, and the Ti—Al based alloy was also detected from the oxygen concentration. It turned out that oxygen was not fully reduced out of 101.

Furthermore, when the ingot once melted was redissolved in the titanium material addition / dissolution step, the oxygen concentration increased from 0.50% by mass to 0.79% by mass in the portion where no inclusion was present. This is because, when pure Ti110 is added to the ingot in the titanium material addition / melting step and the components are adjusted, the oxide inclusions remaining in the ingot are decomposed by pure Ti and become Ti-Al. It is considered that the oxygen concentration has increased due to re-dissolution.

"Comparative Example 2"
In Comparative Example 2, the ingot is melted by the same melting raw material 102 and melting method as in Comparative Example 1. Therefore, the oxygen concentration of the site where the melted ingot inclusions are not present is 0.51% by mass, and the site where the inclusions are present is 1.12% by mass. Of the ingot of Comparative Example 2, a portion where no inclusions were present was selected and melted using a plasma arc melting furnace, and pure Ti110 (oxygen concentration 0.05 mass%) was added to obtain Ti-30. An ingot of mass% Al alloy was melted. As a result of analyzing the oxygen concentration of the molten ingot, the oxygen concentration was 0.42% by mass, which was lower than that of Comparative Example 1.

Therefore, unlike the Comparative Example 1, when a titanium material adding and dissolving step using site inclusions of Al ₂ O ₃ or the like was not almost observed, Al ₂ O ₃ contained in the ingot It can be seen that an increase in oxygen concentration due to the decomposition of oxide inclusions such as is suppressed. However, since the site where inclusions are present cannot be used as a raw material for redissolution, the evaluation of “yield” in Table 1 is an evaluation result of “x” while Comparative Example 1 is “good”. From this, in Comparative Example 2, although the oxygen concentration contained in the ingot can be reduced, the yield is poor, and the overall evaluation is x.

“Comparative Example 3”
In the same manner as in Comparative Example 1 and Comparative Example 2, the melting raw material 102 was prepared so as to be Ti-40 mass% Al-0.8 mass% O, and an ingot (2800 g) was melted. Unlike the comparative example 1 and the comparative example 2, the melting raw material 102 of the comparative example 3 was prepared by dissolving the raw material 102 without adding the flux 103 to the alloy material in the raw material dividing step. It is divided into 11 pieces. Specifically, the first divided body 141 initially charged in the water-cooled copper crucible 105 has a raw material weight of 800 g (excluding the flux 103), and thereafter the second divided body 142 to the eleventh divided portion to be additionally charged. The body 151 has a raw material weight of 200 g. The raw material (800 g) of the first divided body 141 was charged on a starting block made of pure Ti (the bottom 107 of the water-cooled copper crucible 105), and the pressure was 6.6 × 10 ⁴ Pa in an Ar atmosphere. Dissolved in the crucible. After the 1st division body 141 melt | dissolved, the bottom part 107 of the crucible was pulled down for 5 minutes (10 mm) at the speed | rate of 2 mm / min, and the pulling-down operation was implemented. Thereafter, an additional raw material (200 g) of the second and subsequent divided bodies charged in advance in the additional charged raw material feeder is charged into the water-cooled copper crucible 105 and melted, and the bottom 107 of the crucible is lowered after melting. The ingots were melted by performing the process on all of the second divided body 142 to the eleventh divided body 151.

Result of observation of the ingot inside of Comparative Example 3 by SEM after melting, in the same manner as in Comparative Example 1 and Comparative Example 2, the existence and the site of Al ₂ O ₃ of nonmetallic inclusions does not almost exist It was found that the internal part is in the internal tissue. In addition, as a result of analyzing the oxygen concentration of the ingot by the inert gas melting method, the oxygen concentration in the portion where almost no non-metallic inclusions are present is 0.75% by mass, and non-metallic inclusions are present. The oxygen concentration at the site was 0.94% by mass. Therefore, when dissolution and deoxidation are performed without using the flux 103, Al ₂ O ₃ which is a non-metallic inclusion in Ti—Al hardly migrates to the ingot surface, and does not enter the ingot. Since it has remained, it can be seen that even when the dissolved raw material 102 is divided in the raw material dividing step, the oxygen concentration is hardly reduced.

In addition, pure Ti110 (oxygen concentration 0.05 mass%) was added to the ingot of Comparative Example 3 described above using a plasma arc melting furnace, and a Ti-30 mass% Al alloy was melted to produce Ti— A 30% by mass Al alloy ingot was cast and the oxygen concentration of the Ti-30% by mass Al alloy ingot was analyzed. As a result, a result of 0.60% by mass was obtained. From this, as in Comparative Example 1, even if the oxide inclusions remain in the ingot and the pure Ti is added to adjust the components, the oxide inclusions remain in the ingot. Since the oxide inclusions are decomposed by pure Ti and the oxygen concentration in Ti—Al increases, it is determined that the oxygen in the Ti—Al alloy 101 cannot be sufficiently reduced.

"Example 1"
In Example 1, as in Comparative Example 3, the melting raw material 102 was divided into 11 pieces and the ingot was melted. The difference between Example 1 and Comparative Example 3 is that 10% by mass of the flux 103 is blended with respect to the weight of the Ti—Al alloy 101.

When the surface of the ingot taken out after completion of the melting operation was visually confirmed, a layer (surface adhesion flux layer 108) that seems to have been formed by melting / solidifying the added flux 103 was adhered to the surface of the ingot. Observation under the same ingot inside a SEM, most of Al ₂ O ₃ or the like non-metallic inclusions inside the ingot (oxide inclusions) was found not to exist. This was presumed to be due to the transfer of non-metallic inclusions such as Al ₂ O ₃ to the flux layer formed on the ingot surface.

Further, the flux layer on the surface of the ingot (surface-adhered flux layer 108) could be easily removed by shot blasting. As a result of analyzing the oxygen concentration of the ingot from which the surface adhering flux layer 108 has been removed by shot blasting using an inert gas melting method, the oxygen concentration in the portion where Al ₂ O ₃ does not exist is 0.30% by mass. Even at a site where oxide inclusions such as Al ₂ O ₃ were slightly observed, the oxygen concentration was as very low as 0.40% by mass. Therefore, in Example 1 in which the flux 103 was blended in the raw material dividing step and the melting raw material 102 was divided, and the melting operation and the lowering operation were repeated for each divided body in the divided body base ingot manufacturing step. It can be seen that the oxygen concentration inside can be greatly reduced.

Further, while melting the ingot of Example 1 described above using a plasma arc melting furnace, pure Ti110 (oxygen concentration 0.05 mass%) was added to melt an ingot of Ti-30 mass% Al alloy. Then, the oxygen concentration in the ingot of the Ti-30 mass% Al alloy was reduced to 0.25 mass%.

Therefore, unlike the comparative examples 1 to 3, in the titanium material addition / dissolution step of Example 1, almost no oxide inclusions were present in the ingot. It was found that the concentration did not increase and there was no yield reduction. Therefore, by using the production method of the present invention, it is possible to efficiently produce a low-oxygen Ti—Al-based alloy 101 having an Al content of less than 40% by mass with good yield using low-grade raw materials. It is judged that.

"Example 2"
In Example 2, as in Comparative Example 3, the melting raw material 102 was divided into 11 pieces and the ingot was melted. The difference between Example 2 and Comparative Example 3 is that 10% by mass of the flux 103 is blended with respect to the weight of the Ti—Al-based alloy 101.

When the surface of the ingot taken out after completion of the melting operation was visually confirmed, a layer (surface adhesion flux layer 108) that seems to have been formed by melting / solidifying the added flux 103 was adhered to the surface of the ingot. Observation under the same ingot inside a SEM, most of Al ₂ O ₃ or the like non-metallic inclusions inside the ingot (oxide inclusions) was found not to exist. This was presumed to be due to the transfer of non-metallic inclusions such as Al ₂ O ₃ to the flux layer formed on the ingot surface.

Further, the flux layer on the surface of the ingot (surface-adhered flux layer 108) could be easily removed by shot blasting. As a result of analyzing the oxygen concentration of the ingot from which the surface adhering flux layer 108 has been removed by shot blasting using an inert gas melting method, the oxygen concentration of the portion where Al ₂ O ₃ does not exist is 0.045% by mass. Even at a site where oxide inclusions such as Al ₂ O ₃ were slightly observed, the oxygen concentration was as very low as 0.065% by mass. Therefore, in Example 2 in which the flux 103 was blended in the raw material dividing step and the melting raw material 102 was divided, and the melting operation and the lowering operation were repeated for each divided body in the divided body base ingot manufacturing step. It can be seen that the oxygen concentration inside can be greatly reduced.

In addition, while melting the ingot of Example 2 described above using a plasma arc melting furnace, pure Ti10 (oxygen concentration 0.05 mass%) was added to melt an ingot of Ti-30 mass% Al alloy. Then, the oxygen concentration of the ingot of Ti-30 mass% Al No. gold was reduced to 0.057 mass%.

Therefore, unlike the comparative examples 1 to 3, the oxide material inclusions in the ingot were hardly present in the titanium material addition / dissolution step of Example 2, so that even when remelted, oxygen It was found that the concentration did not increase and there was no yield reduction. Therefore, by using the production method of the present invention, it is possible to efficiently produce a low-oxygen Ti—Al-based alloy 101 having an Al content of less than 60 mass% with a high yield using low-grade raw materials. It is judged that.

"Example 3"
In Example 3, as in Comparative Example 3, the melting raw material 102 was divided into 11 pieces and the ingot was melted. Example 3 is different from Comparative Example 3 in that the flux 103 is blended by 10 mass% with respect to the weight of the Ti—Al alloy 101.

When the surface of the ingot taken out after completion of the melting operation was visually confirmed, a layer (surface adhesion flux layer 108) that seems to have been formed by melting / solidifying the added flux 103 was adhered to the surface of the ingot. When the same ingot was observed with an SEM, it was found that almost no non-metallic inclusions (oxide inclusions) such as Al ₂ O ₃ were present in the ingot. This was presumed to be due to the transfer of non-metallic inclusions such as Al ₂ O ₃ to the flux layer formed on the ingot surface.

Further, the flux layer on the surface of the ingot (surface-adhered flux layer 108) could be easily removed by shot blasting. As a result of analyzing the oxygen concentration of the ingot from which the surface-adhered flux layer 108 was removed by shot blasting using an inert gas melting method, the oxygen concentration in the portion where Al ₂ O ₃ does not exist is 0.16% by mass. Even at a site where oxide inclusions such as Al ₂ O ₃ were slightly observed, the oxygen concentration was as low as 0.20% by mass. Therefore, in Example 3 in which the flux 103 was blended in the raw material dividing step and the melting raw material 102 was divided, and the melting operation and the lowering operation were repeatedly performed for each divided body in the divided body base ingot manufacturing step. It can be seen that the oxygen concentration inside can be greatly reduced.

Further, while melting the ingot of Example 3 described above using a plasma arc melting furnace, pure Ti110 (oxygen concentration 0.05 mass%) was added to melt an ingot of Ti-30 mass% Al alloy. Then, the oxygen concentration in the ingot of the Ti-30 mass% Al alloy was reduced to 0.15 mass%.
From this, in the titanium material addition / dissolution step of Example 3, unlike Comparative Examples 1 to 3, there were almost no oxide inclusions in the ingot. It was found that the concentration did not increase and there was no yield reduction. Therefore, by using the production method of the present invention, it is possible to efficiently produce a low-oxygen Ti—Al alloy 101 having an Al content of less than 45 mass% with a high yield using low-grade raw materials. It is judged that.

Example 4
In Example 4, as in Comparative Example 3, the melting raw material 102 was divided into 11 pieces and the ingot was melted. The difference between Example 4 and Comparative Example 3 is that 10% by mass of the flux 103 is blended with respect to the weight of the Ti—Al-based alloy 101.

When the surface of the ingot taken out after completion of the melting operation was visually confirmed, a layer (surface adhesion flux layer 108) that seems to have been formed by melting / solidifying the added flux 103 was adhered to the surface of the ingot. When the same ingot was observed with an SEM, it was found that almost no non-metallic inclusions (oxide inclusions) such as Al ₂ O ₃ were present in the ingot. This non-metallic inclusions of Al ₂ O ₃ or the like is presumed to be due to the transition to the flux layer formed on the ingot surface.

Further, the flux layer on the surface of the ingot (surface-adhered flux layer 108) could be easily removed by shot blasting. As a result of analyzing the oxygen concentration of the ingot from which the surface adhering flux layer 108 has been removed by shot blasting using an inert gas melting method, the oxygen concentration in the portion where Al ₂ O ₃ does not exist is 0.042% by mass. Even at a site where oxide inclusions such as Al ₂ O ₃ were slightly confirmed, the oxygen concentration was as very low as 0.060% by mass. From this, in Example 4 where the flux 103 was blended in the raw material dividing step and the melting raw material 102 was divided, and the melting operation and the lowering operation were repeated for each divided body in the divided body base ingot manufacturing step, the ingot It can be seen that the oxygen concentration inside can be greatly reduced.

In addition, while melting the ingot of Example 4 described above using a plasma arc melting furnace, pure Ti110 (oxygen concentration 0.05 mass%) was added to melt an ingot of Ti-30 mass% Al alloy. Then, the oxygen concentration of the ingot of the Ti-30 mass% Al alloy was reduced to 0.055 mass%.
From this, in the titanium material addition / dissolution step of Example 4, unlike Comparative Examples 1 to 3, there were almost no oxide inclusions in the ingot. It was found that the concentration did not increase and there was no yield reduction. Therefore, by using the production method of the present invention, it is possible to efficiently produce a low-oxygen Ti—Al alloy 101 having an Al content of less than 52 mass% with a high yield using low-grade raw materials. It is judged that.

In addition, it should be thought that embodiment disclosed this time is an illustration and restrictive at no points. In particular, in the embodiment disclosed this time, matters that are not explicitly disclosed, for example, operating conditions and operating conditions, various parameters, dimensions, weights, volumes, and the like of a component deviate from a range that a person skilled in the art normally performs. Instead, values that can be easily assumed by those skilled in the art are employed.

The present application includes a Japanese patent application filed on February 23, 2017 (Japanese Patent Application No. 2017-032273), a Japanese patent application filed on April 13, 2017 (Japanese Patent Application No. 2017-079928), and an application filed on October 11, 2017. This is based on a Japanese patent application (Japanese Patent Application No. 2017-197905), the contents of which are incorporated herein by reference.

According to the present invention, a high-grade and low-oxygen Ti—Al alloy can be efficiently produced from a low-grade titanium material containing oxygen at a high concentration with a high yield, and it is a material for aircraft and automobiles. It is particularly useful in the production of

1 Water-cooled copper container 2 Water-cooled copper mold (secondary ingot manufacturing process)
3 Mechanical means 4 Water-cooled copper mold (titanium material addition / dissolution process)
V Titanium material W Alloy material X Primary ingot Y Secondary ingot Z Ti—Al alloy (O content is less than 0.1% by mass)
Z2 Ti-Al alloy (O content is less than 0.1% by mass and Al content is less than 40% by mass)
α flux β flux layer 101 Ti—Al alloy 102 melting raw material 103 flux 141 first divided body 142 second divided body 143 third divided body 105 water-cooled copper crucible 106 crucible body 107 bottom 108 surface adhesion flux layer 109 water-cooled copper container 110 Pure Ti

Claims (5)

1. Calcium oxide is mixed with 35 to 95% by mass of calcium fluoride with respect to a Ti—Al alloy composed of titanium material and aluminum material and containing 0.1% by mass or more of oxygen and 40% by mass or more of Al. A melting material obtained by adding CaO—CaF ₂ flux to 3-20 mass% with respect to the Ti—Al alloy is melted by a melting method using a water-cooled copper container in an atmosphere of 1.33 Pa or more. A primary ingot manufacturing process for melting the primary ingot by holding;
   A secondary ingot manufacturing step of continuously drawing the primary ingot by a melting method using a bottom-free water-cooled copper mold in an atmosphere of 1.33 Pa or more to obtain a secondary ingot;
   A flux layer removing step of mechanically removing the surface adhering flux layer of the secondary ingot;
   A method for producing a Ti—Al-based alloy, comprising:
2. Calcium oxide is mixed with 35 to 95% by mass of calcium fluoride with respect to a Ti—Al alloy composed of titanium material and aluminum material and containing 0.1% by mass or more of oxygen and 40% by mass or more of Al. A melting raw material in which a CaO—CaF ₂ type flux is blended in an amount of 3 to 20% by mass with respect to the Ti—Al type alloy, A raw material dividing step of dividing n so that the weight is at most 4/5 of the total,
   The first divided body of the molten raw material divided in the raw material dividing step is charged into a bottomless water-cooled copper mold and melted in an inert gas atmosphere of 1.33 Pa or more, and the bottom of the water-cooled copper mold is removed every time. An operation of pulling downward at a speed of 15 mm or less is performed, and then the second divided body of the melted raw material divided in the raw material dividing step is charged into the water-cooled copper mold and an inert gas atmosphere of 1.33 Pa or higher The lower body is melted below and the water-cooled copper mold is pulled downward at a speed of 15 mm or less per minute, and thereafter the divided body base ingot manufacturing step for obtaining an ingot by repeating the above operation up to the nth divided body,
   A flux layer removing step for mechanically removing the flux layer adhering to the surface of the ingot formed in the divided body base ingot manufacturing step;
   A method for producing a Ti—Al-based alloy, comprising:
3. By adding a titanium material to the ingot after the flux layer removing step and dissolving it by a melting method using a water-cooled copper container in an atmosphere of 1.33 Pa or more, a Ti-Al system having an Al content of less than 40% by mass 3. The method for producing a Ti—Al based alloy according to claim 1, wherein an alloy is obtained.
4. The Ti-Al of claim 1, wherein the melting method using the water-cooled copper container in the primary ingot manufacturing process is any one of an arc melting method, a plasma arc melting method, and an induction melting method. Of the production of the aluminum alloy.
5. 3. The melting method using a bottomless water-cooled copper mold in the secondary ingot manufacturing step and the divided body base ingot manufacturing step uses plasma arc or induction heating as a heat source. The manufacturing method of the Ti-Al type alloy as described.

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