JP7220078B2 - Manufacturing method of melting raw material and manufacturing method of titanium casting material - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for producing a raw material containing titanium and melted in an electron beam melting furnace, and a method for producing a titanium casting material using the raw material. In particular, the present invention proposes a technique that enables the effective use of titanium sponge as a raw material for melting in an electron beam melting furnace.

Titanium sponge produced by, for example, reducing purified titanium tetrachloride with metallic magnesium by the Kroll method is used for manufacturing titanium or titanium alloy ingots or slabs and other titanium casting materials. In the production of such titanium casting materials, generally, a vacuum arc melting furnace, an electron beam melting furnace, or the like is used to melt sponge titanium together with alloy additive elements as necessary, and the resulting molten metal is poured into a predetermined mold. Harden.

In melting titanium sponge, an electron beam melting furnace is of interest because it does not require prior fabrication of electrodes containing the titanium sponge as is the case with vacuum arc melting furnaces. In addition, the electron beam melting furnace has the advantage of being excellent in the separation of inclusions called High Density Inclusion (so-called HDI) and Low Density Inclusion (so-called LDI). . In addition, in the electron beam melting furnace, the high vacuum and high temperature in the hearth evaporate the predetermined impurity elements, so the amount of impurities can be reduced.

Patent Documents 1 and 2 disclose conventional techniques for melting sponge titanium and other melting raw materials using an electron beam melting furnace or the like.
In Patent Document 1, for the purpose of "providing a technology for uniformly supplying powdery alloy raw materials and granular metal raw materials to an electron beam melting furnace with a good yield," a method for manufacturing metal ingots using an electron beam melting furnace is disclosed. A metal ingot smelting method characterized by mixing lumped oxides and granular metals in the smelting method and supplying the mixture as a raw material for melting to an electron beam melting furnace.

In addition, Patent Document 2 describes that "sponge titanium particles crushed and sized to a size of about 5 to 19 mm placed on a horizontally arranged flat base are placed upward along the normal line of the flat base. The convexity ratio (Ap/Ach), which is the ratio of the projected area Ap (mm ² ) obtained by projecting more to the area Ach (mm ² ) of the convex hull calculated from the projected shape, is 0.84 or more. and the length Lp (mm) of the peripheral portion of the projected figure calculated from the shape projected onto the flat substrate, and the length Lr (mm) of the circumference of the circle having an area equal to the projected area Ap An aggregate of titanium sponge grains having a Wadell's circularity, which is the ratio (Lr/Lp) of , of 0.55 or more.

WO2008/078402 JP 2018-48362 A

By the way, by reducing purified titanium tetrachloride, titanium sponge is obtained in the form of relatively large lumps (titanium sponge lumps). Since such titanium sponge chunks are too large to be melted in an electron beam melting furnace, the titanium sponge chunks are typically crushed prior to melting into particulate titanium sponge that can be melted in an electron beam melting furnace.
Especially in the electron beam melting furnace, the titanium sponge to be melted is required to have a predetermined size suitable for melting. Therefore, the granular titanium sponge obtained by crushing is sieved using a predetermined sieve, for example, a sieve with an opening of 5 mm × 5 mm, and is sorted into particles having a relatively large particle size and dissolved. used for

Here, the titanium sponge under the sieving cannot be melted satisfactorily in the electron beam melting furnace as it is, and there is a desire for a method of effectively utilizing the relatively small titanium sponge under the sieving. It is Patent Documents 1 and 2 do not discuss how to handle such unsieved sponge titanium.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a method for producing a raw material for melting and a method for producing a titanium casting material, which enable the effective use of a predetermined titanium sponge as a raw material for melting in an electron beam melting furnace.

As a result of intensive studies, the inventors found that a molding raw material containing titanium sponge as a main component, which falls under a sieve with a sieve having a mesh size of 5 mm × 5 mm, is uniaxially pressurized at a pressure of 150 MPa or more to obtain a predetermined size. It was found that this melting raw material can be effectively used for melting in an electron beam melting furnace. However, if the raw material to be formed before the uniaxial pressurization contains a large amount of sponge titanium that passes through a sieve with an opening of 0.2 mm x 0.2 mm, a molten raw material having the required strength can be obtained. Therefore, it was found that an excessively large pressure was required and the solubility of the raw material to be dissolved deteriorated.

Based on this finding, the method for producing a raw material for melting in an electron beam melting furnace of the present invention is a method for producing a raw material for melting that contains titanium and is melted in an electron beam melting furnace, and has a mesh size of 5 mm × 5 mm. By uniaxially pressing a pressure of 150 MPa or more to a molding raw material containing 80% by mass or more of sponge titanium that becomes the bottom of a sieve and the top of a sieve with an opening of 0.2 mm × 0.2 mm, It includes a molding process for molding a melted raw material with a volume of 30 cm ³ or more.

In the method for producing a molten raw material of the present invention, before the molding step, the sponge titanium is treated with titanium oxide, iron oxide, aluminum, vanadium, molybdenum, zirconium, iron, chromium, nickel, copper, niobium, silicon, tin, and A mixing step of obtaining the forming raw material by mixing with an additive raw material containing one or more selected from the group consisting of palladium can be further included.

Further, in the method for producing a molten raw material of the present invention, it is preferable that the sponge titanium has an average particle size of 1 mm to 5 mm.

Further, in the method for producing a molten raw material of the present invention, it is preferable that the molten raw material having a volume of 30 cm ³ to 2000 cm ³ is formed in the forming step.

A method for producing a titanium casting material according to the present invention includes a melting step of melting a raw material for melting produced using any one of the above methods for producing a raw material for melting in an electron beam melting furnace.

According to the method of manufacturing a raw material for melting according to the present invention, it is possible to effectively use a predetermined sponge titanium as a raw material for melting in an electron beam melting furnace.

1 is a flow diagram showing a method for producing a cast titanium material using a method for producing a raw material for melting according to an embodiment of the present invention; FIG.

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described in detail below.
A method for producing a raw material for melting according to one embodiment of the present invention is a method for producing a raw material for melting containing titanium for melting in an electron beam melting furnace. A pressure of 150 MPa or more is applied by uniaxial pressurization to a forming raw material containing 80% by mass or more of sponge titanium that is under a certain sieve and is over a sieve with an opening of 0.2 mm × 0.2 mm. It includes a forming step of forming a melted raw material with a volume of 30 cm ³ or more. If the particle size of the sponge titanium varies, it may be sieved with a sieve having an opening of 5 mm × 5 mm before the molding process to be under the sieve and having an opening of 0.2 mm × 0. A sieving step may be performed to obtain sponge titanium on the sieve by sieving with a sieve of 0.2 mm, but this sieving step is optional. In addition, if necessary, a mixing step of mixing sponge titanium having the above particle size with a predetermined additive raw material can be further included before the molding step.

The raw material to be melted produced by such a method for producing raw material to be melted is melted in an electron beam melting furnace in the melting process, and then the molten metal is poured into a mold and cooled and hardened through a casting process, etc. Predetermined titanium castings can be produced. FIG. 1 illustrates a method for producing such a titanium casting material.

(sponge titanium)
As sponge titanium, for example, one obtained as follows can be used. To obtain sponge titanium, titanium ore such as rutile or ilmenite containing titanium oxide as a main component is usually supplied to a chlorination furnace together with chlorine gas and a carbon source such as coke as a reducing agent to produce titanium tetrachloride. This titanium tetrachloride, commonly referred to as crude titanium tetrachloride, is then distilled to remove impurities to form purified titanium tetrachloride. After that, for example, by reducing the purified titanium tetrachloride with metallic magnesium as in the Kroll method, a sponge titanium mass is obtained.

Such titanium sponge lumps are usually large lumps and are crushed prior to melting in an electron beam melting furnace. Various crushers or devices can be used for crushing the titanium sponge lumps. For example, a known special titanium sponge cutting machine or the like may be used.

(Sieving process)
A sieving step of sieving the titanium sponge may be performed prior to melting in the electron beam melting furnace. Here, a sieve having a square mesh size of 5 mm×5 mm is used. As a result, relatively coarse-grained titanium sponge screened on the sieve can be directly used for melting in an electron beam melting furnace. The sponge titanium on the sieve may have 99% by mass or more of which the particle size is within the range of 5.6 mm to 22.4 mm. This sieve means a metal mesh sieve defined in JIS Z8801-1:2006. The same applies to a sieve with an opening of 0.2 mm×0.2 mm, which will be described later.

On the other hand, in the sieving by the sieve, comparatively fine-grained titanium sponge is obtained under the sieve, but this titanium sponge cannot be melted in an electron beam melting furnace as it is. This is because such fine-grained titanium sponge separates from the larger titanium sponge on the feeder and hearth of the electron beam melting furnace, so that the amount of dissolved titanium sponge is not stable as a whole, and the composition of the titanium casting material varies. Due to the fact that it is easy to

In order to make effective use of such fine-grained titanium sponge, in this embodiment, as described later, the fine-grained titanium sponge is subjected to a mixing step as necessary, followed by a molding step, followed by dissolution. A raw material is obtained, and the molten raw material can be satisfactorily melted in an electron beam melting furnace. In addition, since the fine-grained titanium sponge that passes through a sieve with a mesh size of 5 mm×5 mm is molded under a predetermined pressure in the subsequent molding step, a molten raw material having good strength can be obtained. It is difficult to break until it is fed to the feed and even after it is fed, and it is easy to control the amount of raw material to be dissolved. Therefore, it is possible to suppress variations in the amount of ingredients in the titanium cast material produced through melting and casting.

However, if the titanium sponge that passes through a sieve with a mesh size of 5 mm × 5 mm contains a certain amount of particularly fine sponge titanium particles, it is necessary to use excessively large particles during molding in order to obtain a molten raw material having the required strength. pressure is required. Further, since the fine sponge titanium particles increase the density, the melted raw material after molding using a large amount of such fine sponge titanium particles has a high density and deteriorates the solubility. In order to remove such extremely fine titanium sponge particles, further sieving is performed using a sieve with an opening of 0.2 mm×0.2 mm, and the particles on the sieve are selected.
In this way, the sponge titanium that is below the sieve with an opening of 5 mm × 5 mm and above the sieve with an opening of 0.2 mm × 0.2 mm is included in the forming raw material described later. Thus, it becomes possible to produce a good molten raw material.

Sponge titanium that is under the sieve with a mesh size of 5 mm × 5 mm and above the sieve with a mesh size of 0.2 mm × 0.2 mm corresponds to the main raw material to be included in the forming raw material here. do. This "main raw material" means a raw material contained in the molding raw material at a rate of 80% by mass or more. Regardless of whether sieving is actually performed, if sieving is performed with a sieve with an opening of 5 mm × 5 mm, it will be under sieved, and with a sieve with an opening of 0.2 mm × 0.2 mm. Titanium sponge is the above-mentioned sponge titanium. Therefore, the sieving step is not necessarily required. It should be noted that those that pass through a sieve with an opening smaller than 5 mm×5 mm also pass through a sieve with an opening of 5 mm×5 mm.

The titanium sponge under and above the predetermined sieve as described above preferably has an average particle size of 1 mm to 5 mm. When the average particle size of sponge titanium is such a size, the surface area is increased to some extent, and it becomes possible to uniformly adhere fine additive raw materials such as titanium oxide to the surface. In addition, since the bulk density of titanium sponge can be maintained at a low level, compression molding can be performed even at a relatively low pressure in the later-described molding process. This average particle size refers to the particle size at which the volume-based cumulative distribution is 50% in particle size distribution measurement obtained by a laser diffraction/scattering method, and is measured based on JIS Z8825:2013.

(Mixing process)
Next, sponge titanium (hereinafter also simply referred to as “sponge titanium”) that is under the sieve with a mesh size of 5 mm × 5 mm and above the sieve with a mesh size of 0.2 mm × 0.2 mm as described above, A mixing step can be performed for mixing with a predetermined additive raw material to obtain a molding raw material.
In the mixing step, the additive raw material to be mixed with sponge titanium is selected from the group consisting of titanium oxide, iron oxide, aluminum, vanadium, molybdenum, zirconium, iron, chromium, nickel, copper, niobium, silicon, tin and palladium. It may contain one or more materials. Titanium in forms other than sponges, such as titanium scraps and titanium chips, is also treated as an additive material. Such an additive raw material can be mixed with sponge titanium in a material and a predetermined amount according to the target composition of the titanium cast material to be manufactured. That is, a raw material that is an alloy element alone may be used, or a raw material that is an alloy may be used.

Since titanium is generally easily oxidized, it is important to control the amount of oxygen in the production of titanium casting materials. If the amount of oxygen in the titanium cast material can be appropriately controlled, it is possible to appropriately increase the strength of the sheet material. In this embodiment, in the mixing step, the fine-grained titanium sponge and the additive raw material such as titanium oxide can be well mixed, and in the subsequent molding step, this is molded into the molten raw material, so that the electronic It becomes possible to highly control the supply amount of each component to the beam melting furnace. As a result, the manufactured titanium casting material has a reduced variation in the amount of the added components.
In the conventional method, a mixture of calcined pellets such as titanium oxide and sponge titanium was charged into the electron beam melting furnace, so the amount of each component charged was not stable, and the titanium casting material, especially the oxygen content, was uneven. There was room for improvement. On the other hand, in the present embodiment, since the sponge titanium and the additive raw material are formed into the molten raw material and then charged into the electron beam melting furnace, the separation of each raw material in the feeder can be suppressed satisfactorily.

The additive raw material may have an average particle size of 50 mm or less and 25 mm or more. The average particle size of the additive raw material having such a relatively large size is the same area as the area of the particles of the additive raw material obtained by image analysis from the image obtained by photographing the additive raw material for 1000 additive raw materials. means the mean value of the diameters of the circles with

The proportion of the additive raw material in the molding raw material can be appropriately determined according to the purpose of addition, etc., but can be, for example, 20% by mass or less, typically 1% by mass to 10% by mass. However, some titanium casting materials to be manufactured, such as titanium ingots or titanium slabs, do not require mixing with additive raw materials. In this case, the mixing step may be omitted, and the proportion of the additive material in the forming material may be 0% by mass. Note that titanium oxide may be mixed as an additive raw material even when a titanium casting material containing no alloying elements is produced.

The titanium sponge and the additive raw material can be mixed by mechanically mixing the titanium sponge and the additive raw material using a known mixing means.

(Molding process)
In the subsequent molding process, the above-described molding raw material is subjected to uniaxial pressurization using a press die or the like to apply a pressure of 150 MPa or more. As a result, the forming raw material is compressed to form a molten raw material having a predetermined shape. Uniaxial pressurization is preferably carried out by molding using a mold, particularly molding using a mold.

Here, the forming raw material contains 80% by mass or more of titanium sponge that passes through a sieve with an opening of 5 mm×5 mm and remains on the sieve with an opening of 0.2 mm×0.2 mm. In this embodiment, even if most of the forming raw material is composed of predetermined fine sponge titanium particles, it is possible to form a molten raw material having good strength and an intended shape. As a result, it is possible to easily control the amount of raw material to be melted into the electron beam melting furnace in the melting step described below, and to produce a good titanium cast material with small variations in component amounts.

If the forming raw material contains 80% by mass or more of the titanium sponge, the remaining part of the raw material is sponge titanium that is above the sieve with a mesh size of 5 mm×5 mm and a mesh size of 0.2 mm×0.2 mm. It may contain sponge titanium that falls under a sieve of 2 mm and/or the above-mentioned additive raw materials. Further, the fine sponge titanium particles in the forming raw material may include, for example, "deformed sponge titanium particles" as described in Patent Document 2.

Here, in the molding process, various powder molding machines capable of uniaxial pressing can be used. A commercially available machine can be used as such a powder molding machine. Among others, the use of a molding machine that employs uniaxial pressure using a metal mold has the advantage of being able to continuously mold briquettes having excellent strength. The powder molding machine may be driven by any type, but may be hydraulically driven, for example.

In the molding step, a molten raw material having a required strength can be obtained by applying a pressure of 150 MPa or more to the molding raw material in a uniaxial direction. As a result, in the melting process, it is possible to satisfactorily suppress unintended collapse of the material when the raw material to be melted is put into the electron beam melting furnace. From the viewpoint of improving the strength of the molten raw material, the pressure applied to the molten raw material is preferably 180 MPa or higher. The upper limit of the pressure during molding can be set to a predetermined value that is appropriately set in consideration of the specifications of the device, the manufacturing cost, and the like. For example, the pressure can be 250 MPa or less.
The temperature during molding is generally 5°C to 50°C. However, the temperature at the time of molding can be appropriately set in consideration of the components contained in the molten raw material, the desired properties of the molten raw material, etc., and is not limited to this range.

The shape of the melted raw material obtained by molding as described above is not particularly limited, but it can be substantially in the form of a briquette such as a cylinder, a rectangular parallelepiped, a sphere, or a combination thereof. The volume of the raw material to be dissolved can be, for example, 30 cm ³ to 2000 cm ³ , preferably 30 cm ³ to 300 cm ³ . By increasing the volume of the raw material to be melted to a certain extent of 30 cm ³ or more, it becomes easier to make the shapes and components of the raw materials to be melted uniform. Further, by limiting the volume of the raw material to be dissolved to a predetermined size of 2000 cm ³ or less, it becomes easier to control the deposited state of the raw material to be dissolved during feeding.
The raw material to be melted may be formed into a shape that can be used as a bar feeder for an electron beam melting furnace. A bar feeder is a relatively large lump that is charged into the furnace from outside the electron beam melting furnace and melted by irradiation of the electron beam from the upper side of the hearth, and the molten metal is filled in the hearth. supplied. The bar feeder is generally charged into the electron beam melting furnace from a position different from that of the molten raw material in the form of small blocks of, for example, 300 cm ³ or less, but the charging position of the bar feeder can be determined as appropriate. In this case, the volume of the raw material to be melted as a bar feeder can be, for example, 2000 cm ³ to 20000 cm ³ .

(Melting process)
A melting step of melting the molten raw material obtained in the above forming step in an electron beam melting furnace can be performed.

A known electron beam melting furnace for melting the raw material in the melting process can be used. It is common to have a feeder that guides the hearth, an electron beam irradiator that irradiates the molten metal in the hearth with an electron beam, and a mold that cools and hardens the molten metal poured from the hearth. In some cases, the electron beam melting furnace may also have a bar feeder.

As described above, the raw material to be melted contains a predetermined amount of sponge titanium, and is molded under a predetermined pressure by uniaxial pressurization. In addition, material collapse is unlikely to occur from the time it is put into the electron beam melting furnace to the hearth. As a result, it is possible to greatly contribute to the production of good titanium casting materials with small variations in the component amounts. It should be noted that the melted raw material produced in the above-described embodiment and the coarse-grained sponge titanium that becomes the top of a sieve with a mesh size of 5 mm×5 mm may be used together for melting.

(Casting process)
After the melting process, a casting process can be performed in which the molten metal obtained in the melting process is poured into a predetermined mold and cooled to harden. Thereby, a titanium casting material can be produced. Specific examples of the titanium casting material include an ingot with a substantially circular cross section, an ingot with a substantially rectangular cross section, a slab, a bloom, a billet, etc., but the shape is not particularly limited.

Next, the method for producing a molten raw material according to the present invention was experimentally carried out, and its effects were confirmed, which will be described below. However, the description herein is for illustrative purposes only and is not intended to be limiting.

<Manufacturing raw materials for melting>
(Example 1)
After crushing the sponge titanium mass, it was screened with a sieve with an opening of 5 mm × 5 mm and a sieve with an opening of 0.2 mm × 0.2 mm, and it was under the sieve with an opening of 5 mm × 5 mm and A titanium sponge was obtained which was 0.2 mm x 0.2 mm in size and was sieved.

After mixing 90% by mass of the sponge titanium and 10% by mass of additive raw materials such as titanium scrap corresponding to two types of pure titanium of JIS H4600 to obtain a forming raw material, the forming raw material is processed in a briquette machine (manufactured by RUF Co., Ltd.). RUF4/3700 60×40) was pressure-molded at 200 MPa to prepare a briquette as a molten raw material. The briquette had a substantially rectangular shape and a size of about 40 mm×60 mm×30 mm (volume of about 72 cm ³ ). This briquette machine uses a metal mold, is of a uniaxial pressure type, and is hydraulically driven.

Titanium scrap, which is an additive raw material, corresponds to JIS H4600 Class 2 pure titanium, and has an average size of 10 mm×20 mm×2 mm.

(Example 2)
A briquette was produced in the same manner as in Example 1, except that titanium oxide was included as an additive raw material, and the contents of sponge titanium and titanium oxide in the forming raw material were 90% by mass and 10% by mass, respectively. Note that the average particle size of titanium oxide is 0.2 μm.

(Comparative example 1)
A briquette was produced in the same manner as in Example 1, except that the pressure in the briquette machine was 98 MPa.

(Comparative example 2)
A briquette was produced in the same manner as in Example 1, except that the ratio of titanium sponge in the raw material for molding was 70% by mass and the ratio of titanium scrap was 30% by mass.

(Comparative Example 3)
A briquette was produced in the same manner as in Example 2, except that the pressure in the briquette machine was 98 MPa.

(Comparative Example 4)
A briquette was produced in the same manner as in Example 2, except that the ratio of sponge titanium in the forming raw material was 70% by mass and the ratio of titanium oxide was 30% by mass.

(Comparative Example 5)
An attempt was made to produce a briquette in the same manner as in Example 1, except that the volume of the briquette was 10 cm ³ . It was determined that the briquettes could not be made because the

(evaluation)
The briquettes of Examples 1 and 2 and Comparative Examples 1 to 4 were dropped from a height of 5 m, and after dropping, the briquettes were checked for breakage or material collapse. As a result, the briquettes of Examples 1 and 2 did not break or lose their shape, whereas all of the briquettes of Comparative Examples 1 to 4 were broken and the broken portions were separated into pieces.

In addition, it was confirmed whether or not the amount of briquettes fed into the electron beam melting furnace could be controlled. In Examples 1 and 2, the briquettes could be charged without problems, whereas in Comparative Examples 1 to 4, the briquettes were broken after charging, and the amount of the separated briquettes could not be controlled due to the breakage, resulting in an uneven composition of the molten metal.

<Production of Titanium Cast Material>
(Example 3)
The amount of sponge titanium in the forming raw material is 80% by mass, the additive raw material further contains aluminum and vanadium, the aluminum content in the molten raw material is 6% by mass, and the vanadium content in the molten raw material is 4% by mass. Briquettes were made in the same manner as in Example 1, except that Using this briquette as a raw material for melting, a titanium casting material was produced using an electron beam melting furnace.

(Comparative Example 6)
A briquette was produced in the same manner as in Example 3, except that the amount of sponge titanium in the forming raw material was 70% by mass and the amount of additive raw materials such as titanium scrap was 20% by mass. Using this briquette as a raw material for melting, a titanium ingot as a titanium casting material was produced using an electron beam melting furnace.

(evaluation)
Variations in the alloy composition of each titanium cast material of Example 3 and Comparative Example 6 were confirmed by longitudinal component analysis of the titanium cast material. Here, the alloy components were measured at a pitch of 100 mm from the bottom to the top of the titanium casting material. For the measurement of the alloy composition, a cylindrical pin sample with a diameter of 6 mm and a length of 30 mm is taken from the titanium casting material using a drill at each measurement point, and ICP emission spectroscopy is applied to the pin sample. It was done by Then, the measured value at each measurement point was divided by the target value of the titanium cast material, and expressed as a percentage to calculate the relative error as the dispersion of the alloy composition. Since the change in aluminum concentration is greater than the change in vanadium concentration, the relative error of the aluminum concentration was obtained here.
As a result, the maximum value of the relative error of the titanium cast material of Example 3 was 3%. On the other hand, the maximum value of the relative error of the alloy composition of the titanium cast material of Comparative Example 6 was 10%. In Example 3, it is presumed that the variation in the alloy components was small because the introduction of the raw material to be melted could be appropriately controlled, and the unintended evaporation of the alloying elements such as aluminum could be suppressed satisfactorily.

Claims (6)

A method for producing a molten raw material containing titanium and melted in an electron beam melting furnace, comprising:
150 MPa or more for a forming raw material containing 80% by mass or more of sponge titanium that becomes under a sieve with a mesh size of 5 mm × 5 mm and over a sieve with a mesh size of 0.2 mm × 0.2 mm. including a molding step of molding a molten raw material with a volume of 30 cm ³ or more by uniaxial pressurization of a pressure of
A method for producing a molten raw material , wherein the forming raw material contains titanium oxide. Before the molding step, the sponge titanium and the titanium oxide are selected from the group consisting of iron oxide, aluminum, vanadium, molybdenum, zirconium, iron, chromium, nickel, copper, niobium, silicon, tin, and palladium. 2. The method for producing a molten raw material according to claim 1, further comprising a mixing step of obtaining said forming raw material by mixing with additive raw materials including the above. 3. The method for producing a molten raw material according to claim 1, wherein the sponge titanium has an average particle size of 1 mm to 5 mm. The method for producing a molten raw material according to any one of claims 1 to 3, wherein the molding step forms a molten raw material having a volume of 30 cm ³ to 2000 cm ³ . 5. The method for producing a raw material to be melted according to claim 1, wherein the electron beam melting furnace produces a titanium cast material. A method for producing a titanium casting material, comprising a melting step of melting, in an electron beam melting furnace, a raw material to be melted produced by the method for producing a raw material to be melted according to any one of claims 1 to 5.

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