JP2021079397A - Manufacturing method of titanium ingot, and mold for manufacturing titanium ingot - Google Patents

Abstract

To provide a manufacturing method of a titanium ingot, capable of preventing the scattering of a molten metal at the time of breakout occurrence, and to provide a mold for manufacturing a titanium ingot.SOLUTION: A manufacturing method of a titanium ingot includes a casting step of forming a titanium ingot by impregnating a titanium-containing molten metal into a mold 5. The mold 5 has an unbottomed cylindrical barrel body 50, and an upper end of the barrel body 50 includes an opening 51 for receiving a molten metal. An inner peripheral surface of the barrel body 50 includes a reversely tapered surface 53 arranged in a position below a position of the opening 51, and in the reversely tapered surface 53, a distance from a center axis P of the barrel body 50 is made long as it is getting downward.SELECTED DRAWING: Figure 2

Description

The present invention relates to a method for producing a titanium ingot and a titanium ingot production mold.

Titanium has a high melting point of about 1680 ° C. and is a highly reactive metal that is violently air-oxidized at the melting temperature. For this reason, it is difficult to melt titanium in an atmospheric atmosphere using a crucible made of a refractory material such as a steel material. Therefore, when manufacturing titanium ingots, a mold having a water-cooled structure is used. Titanium ingots are produced by continuously injecting a molten material (molten metal) melted using an electron beam or plasma into a mold and drawing the molten metal out of the mold while solidifying the molten metal in the mold. When this is pulled out, defects such as wrinkles, surface cracks, and scratches with the mold may occur on the surface of the titanium ingot.

Patent Document 1 discloses a continuous casting method of an ingot capable of casting an ingot having a good casting surface condition. In the casting method described in Patent Document 1, an ingot made of titanium or a titanium alloy is continuously formed by injecting a molten metal in which titanium or a titanium alloy is dissolved into a bottomless mold and pulling it downward while solidifying it. Cast to. At this time, the molten metal solidifies by controlling at least one of the temperature of the surface portion of the ingot in the contact region between the mold and the ingot and the heat flux passing from the surface portion of the ingot to the mold in the contact region. The thickness of the solidified shell in the contact area is kept within a predetermined range.

Japanese Unexamined Patent Publication No. 2014-133257

However, the formation of the solidified shell is not determined only by cooling by contact with the mold, but also largely depends on the temperature or flow condition of the molten metal. Therefore, as described in Patent Document 1, even if the temperature of the surface portion of the ingot or the heat flux passing from the surface portion of the ingot to the mold is controlled, the thickness of the solidified shell may not be controlled. .. As a result, it may not be possible to suppress the occurrence of defects such as wrinkles on the surface of the ingot.

If a defect occurs on the surface, when the ingot is pulled out from the mold, the defect may break and a breakout may occur in which the molten metal inside the ingot leaks out. When this breakout occurs, the molten metal scatters around the mold, and it is desirable to prevent this.

Therefore, an object of the present invention is to provide a method for producing a titanium ingot and a titanium ingot production mold capable of preventing the molten metal from scattering when a breakout occurs.

In order to achieve the above object, the method for producing a titanium ingot of the present invention includes a casting step of injecting a molten metal containing titanium into a mold to form a titanium ingot, and the mold has a bottomless tubular shape. The fuselage is provided, the upper end of the fuselage includes an opening for receiving the molten metal, and the inner peripheral surface of the fuselage includes a tapered tapered surface arranged at a position below the position of the opening. The tapered surface has a longer distance from the central axis of the body as it advances downward.

Further, the titanium ingot manufacturing mold of the present invention includes a bottomless tubular body, the upper end of the body includes an opening for receiving a molten metal containing titanium, and the inner peripheral surface of the body is a surface. The tapered tapered surface is included at a position lower than the position of the opening, and the tapered tapered surface becomes longer in distance from the central axis of the fuselage as it advances downward.

According to the present invention, the tapered surface can prevent the molten metal from scattering when a breakout occurs.

FIG. 1 is a diagram showing a titanium ingot manufacturing apparatus. FIG. 2 is a cross-sectional view of the mold. FIG. 3 is a cross-sectional view of the mold in a state where the molten metal is injected into the mold. FIG. 4 is a cross-sectional view of the mold in a state where the molten metal is injected into the mold. FIG. 5 is a cross-sectional view of the mold which is the first modification. FIG. 6 is a cross-sectional view of the mold in which the molten metal is injected into the mold of the modified example 1. FIG. 7 is a cross-sectional view of the mold which is the second modification.

<Titanium ingot manufacturing equipment>
FIG. 1 is a diagram showing a manufacturing apparatus 1 for a titanium ingot 72. The manufacturing apparatus 1 includes a raw material supply unit 2, irradiation units 31, 32, 33, a hearth 4, a titanium ingot manufacturing mold (hereinafter, simply referred to as a mold) 5, and a support base 6.

The raw material supply unit 2 supplies a titanium alloy raw material (hereinafter, simply referred to as a raw material) 70 to the hearth 4 in the subsequent stage. The raw material supply unit 2 is arranged above the hearth 4. The raw material supply unit 2 has a table 21 on which the raw material 70 is placed and an extruder 22 for extruding the raw material 70 placed on the table 21. The raw material 70 extruded into the extruder 22 falls to the hearth 4 located below the raw material supply unit 2.

It is desirable that the raw material 70 is a titanium briquette (including a titanium alloy briquette; the same applies hereinafter). The raw material 70 is not limited to the titanium briquette, and scraps such as plates, rods, and pipes may be mixed with the titanium alloy raw material as needed. In the following description, the case where the raw material 70 is a titanium briquette will be taken as an example. As the raw material 70, any of a pure titanium raw material, a titanium alloy raw material, a titanium and aluminum mixed raw material, and a titanium and titanium alloy mixed raw material can be used.

The irradiation unit 31 irradiates the raw material 70 supplied from the raw material supply unit 2 to the hearth 4 with an electron beam or plasma to dissolve the raw material 70. It is preferable that the raw material supply unit 2 supplies the raw material 70 by the extruder 22 at a supply rate corresponding to the dissolution rate of the raw material 70 by the irradiation unit 31. Further, it is preferable that the raw material supply unit 2 continuously supplies the raw material 70 and the irradiation unit 31 continuously dissolves the raw material 70.

The hearth 4 houses the molten metal 71 in which the raw material 70 is dissolved by the irradiation unit 31. The hearth 4 cools and solidifies a part of the molten metal 71 to form a skull on the bottom, and flows the remaining molten metal 71 to the mold 5 in the subsequent stage.

The irradiation unit 32 is arranged above the hearth 4, and irradiates the surface of the molten metal 71 in the hearth 4 with an electron beam or plasma. As a result, the temperature of the molten metal 71 in the hearth 4 is adjusted.

The mold 5 has a bottomless tubular shape. The molten metal 71 is injected into the mold 5 from the hearth 4. The mold 5 cools and solidifies the injected molten metal 71. When the molten metal 71 is cooled and solidified in the mold 5, for example, a columnar titanium ingot 72 is formed while extending downward. The molten metal 71 injected into the mold 5 becomes a titanium ingot 72 by contact with the inner peripheral surface of the upper part of the mold 5. Therefore, in the upper part of the mold 5, the molten metal 71 exists inside the titanium ingot 72 when viewed from the axial direction of the mold 5. Further, at the interface between the cooled and solidified titanium ingot 72 and the molten metal 71, the molten metal 71 is cooled and solidified to form the titanium ingot 72. The structure of the mold 5 will be described later.

The support base 6 is arranged below the mold 5. The support base 6 is configured to move in the vertical direction by a moving mechanism (not shown). A dummy block (not shown) is formed on the support base 6. The lower end of the titanium ingot 72 is supported by the dummy block. The support base 6 pulls out the titanium ingot 72 from the mold 5 by moving downward while supporting the titanium ingot 72. At the time of this drawing, if the quality required for the titanium ingot 72 is high, the lubricant cannot be used in the mold 5. Further, in casting the titanium ingot 72, the support base 6 is slowly and intermittently moved and the support base 6 is repeatedly pushed upward to pull out the titanium ingot 72 from the mold 5.

The irradiation unit 33 is arranged above the mold 5. The irradiation unit 33 irradiates the molten metal 71 housed in the mold 5 while scanning an electron beam or plasma to adjust the temperature of the molten metal 71.

The irradiation units 31, 32, and 33 have the same configuration, and one or more of them are arranged. When the irradiation units 31, 32, 33 are configured to irradiate an electron beam, the irradiation units 31, 32, 33 have a known electron beam generator such as an electron beam gun. In this case, the parts 2, 4, 5, and 6 of the manufacturing apparatus 1 are placed in a vacuum atmosphere. When the irradiation units 31, 32, and 33 are configured to irradiate plasma, they have a known plasma generator. In this case, the parts 2, 4, 5, and 6 of the manufacturing apparatus 1 are placed in an atmosphere of an inert gas such as argon gas.

<About the mold>
Next, the configuration of the mold 5 will be described in detail. FIG. 2 is a cross-sectional view of the mold 5.

The mold 5 has a bottomless cylindrical body 50. The body 50 includes an opening 51 at the upper end thereof, which forms an opening 51A for receiving the molten metal 71 from the hearth 4. Further, the inner peripheral surface of the body 50 below the opening 51 includes a cylindrical straight body surface 52 parallel to the central axis P. Further, the inner peripheral surface of the body 50 below the straight body surface 52 includes a truncated cone-shaped tapered surface 53. The tapered tapered surface 53 has a longer distance from the central axis P of the body 50 as it advances downward. The tapered tapered surface 53 is inclined with respect to the central axis P to such an extent that a gap 102 (see FIG. 4 described later) is formed between the tapered titanium ingot 72 and the columnar titanium ingot 72 that is formed while extending downward. Is preferable. Further, the taper ratio of the tapered tapered surface 53 is preferably 1 to 50 (% / m).

<About breakout>
By providing the mold 5 with a tapered tapered surface 53, it is possible to prevent the molten metal 71 from scattering when a breakout occurs.

3 and 4 are cross-sectional views of the mold in which the molten metal is injected into the mold 5.

The molten metal 71 injected into the mold 5 forms a titanium ingot 72 by contact with the straight body surface 52, which is the inner peripheral surface near the opening 51 of the mold 5. Immediately before the titanium ingot 72 is formed, the vicinity of the molten metal surface of the molten metal 71 has a curvature due to surface tension. In this state, when the molten metal 71 comes into contact with the straight body surface 52 of the mold 5 and is cooled and solidified, a titanium ingot 72 having a curvature is formed, and a gap 101 is formed between the mold 5 and the titanium ingot 72. .. After that, when the molten metal 71 newly injected into the mold 5 is partially supplied to the gap 101, hot water wrinkles are formed.

As described above, the drawing speed of the titanium ingot 72 is slow, and the solidification shrinkage of the titanium ingot 72 progresses. If the length of the straight body surface 52 of the mold 5 is long, the friction between the straight body surface 52 of the mold 5 and the surface of the titanium ingot 72 is large, and the fragile titanium ingot 72 opens and breaks at a high temperature. It will be. If the breaking depth is large, a breakout occurs in which the molten metal 71 inside the titanium ingot 72 leaks out. Further, when pulling out, the support base 6 may be pushed up upward. In this case, the frictional force between the surface of the titanium ingot 72 and the straight body surface 52 of the mold 5 increases, and the titanium ingot 72 breaks, causing breakout.

When a breakout occurs, the molten metal 71 scatters outside the mold 5. Therefore, by providing a tapered tapered surface 53 below the straight body surface 52 and providing a gap 102 between the tapered tapered surface 53 and the titanium ingot 72, the scattered molten metal 71 can be treated with the tapered tapered surface 53. Is received by. Therefore, it is possible to prevent the molten metal 71 from scattering to the outside of the mold 5.

As described above, by providing the mold 5 with a tapered tapered surface 53, it is possible to prevent the molten metal from scattering when a breakout occurs.

<Manufacturing method of titanium ingot>
Next, a method for manufacturing the titanium ingot 72 according to the present embodiment will be described with reference to FIG. The method for producing the titanium ingot 72 has the first to fourth steps.

The first step is a raw material supply step. In this first step, the raw material supply unit 2 drops the raw material 70 onto the hearth 4. In the raw material supply step, it is desirable to supply the raw material 70 at a supply rate corresponding to the dissolution rate of the raw material 70 in the second step.

The second step is a melting step. In this second step, the raw material 70 is dissolved by the irradiation unit 31 irradiating the raw material 70 supplied to the hearth 4 with an electron beam or plasma. It is desirable that the raw material 70 is continuously supplied in the raw material supply step and the raw material 70 is continuously melted in the melting step.

The third step is a refining step of refining the molten metal 71 in Haas 4. In this third step, the molten metal 71 that falls as a solid substance or is melted by the irradiation unit 31 and flows down is refined. Further, in the refining step, the temperature of the molten metal 71 is adjusted by irradiating the molten metal 71 flowing through the hearth 4 with an electron beam or plasma from the irradiation unit 32.

The fourth step is the casting step. In this fourth step, the molten metal 71 refined by the hearth 4 is injected into the mold 5, and the molten metal 71 is cooled and solidified by the mold 5 to form the titanium ingot 72. In this casting step, the support base 6 moves downward as the molten metal 71 flows into the mold 5. As a result, the titanium ingot 72 is formed into a columnar shape.

In this fourth step, even if wrinkles or the like are formed on the surface of the titanium ingot 72 and breakout occurs, the molten metal 71 scattered can be received by the tapered tapered surface 53.

As described above, by providing the mold 5 with a tapered tapered surface 53, it is possible to prevent the molten metal from scattering when a breakout occurs.

<Modification example>
FIG. 5 is a cross-sectional view of the mold 5A which is the first modification.

The mold 5A has a truncated cone-tapered tapered surface 54 located below the opening 51. The tapered surface 54 is shortened in distance from the central axis P of the body 50 as it advances downward. Further, the inner peripheral surface of the mold 5A includes a tapered tapered surface 53 below the tapered tapered surface 54.

A solidifying region for solidifying the molten metal 71 injected into the mold 5 is set on the inner peripheral surface of the mold 5A. The solidification region is set so as to straddle the tapered tapered surface 54 and the tapered tapered surface 53. That is, when the molten metal 71 injected into the mold 5A comes into contact with the tapered tapered surface 54 and the tapered tapered surface 53 in the vicinity of the boundary, the titanium ingot 72 is formed.

FIG. 6 is a cross-sectional view of the mold 5A in a state where the molten metal 71 is injected into the mold 5A of the modified example 1. The molten metal 71 injected into the mold 5A is injected so that the surface of the molten metal is in contact with the tapered surface 54. Then, the molten metal 71 is partially cooled and solidified by the contact between the tapered tapered surface 54 and the tapered tapered surface 53. The portion that has been cooled and solidified includes an outer peripheral wall 71A formed by solidifying the molten metal 71 and a molten metal 71 surrounded by the outer peripheral wall. In the vicinity of the molten metal surface, the inner peripheral surface of the mold 5A advances toward the titanium ingot 72 side as it goes downward. That is, there is no gap between the inner peripheral surface of the mold 5 and the titanium ingot 72 for the molten metal 71 to enter.

As a result, unlike the case described with reference to FIG. 3, a gap is not formed between the mold 5A and the titanium ingot 72. As a result, the formation of gaps that cause the formation of wrinkles can be suppressed, and the formation of wrinkles can be prevented. Further, even when hot water wrinkles are formed and breakout occurs, the tapered tapered surface 53 of the mold 5A can prevent the molten metal from scattering when breakout occurs.

The taper ratio γ of the tapered tapered surface 54 is preferably set to 0.5 to 30 (% / m) in order to prevent the formation of wrinkles. Here, as shown in FIG. 5, the height (mm) of the tapered tapered surface 54 in the direction orthogonal to the central axis P of the body 50 is represented by “a”. Specifically, "a" is an absolute value of the difference between the radius of the upper end of the tapered tapered surface 54 centered on the central axis P and the radius of the lower end of the tapered tapered surface 54. Further, the maximum inner diameter (mm) of the tapered tapered surface 54 is represented by "W". The length (mm) of the tapered tapered surface 54 in the direction along the central axis P is represented by "L". In this case, the taper ratio γ is expressed by the following equation.
γ = {(a / W) / (L / 1000)} × 100 (% / m)
If γ is less than 0.5%, the effect of suppressing wrinkles cannot be sufficiently exhibited. When γ exceeds 30%, the diameter of the titanium ingot 72 becomes small, and the productivity decreases.

Note that "a", "W", and "L" may be defined as _{"a 1} ", "W ₁ ", and "L ₁ ", respectively, based on the surface of the molten metal 71 injected into the mold 5. Good. The taper ratio in this case is defined _{as γ 1.} The molten metal 71 is injected so that the surface of the molten metal is in contact with the tapered surface 54 in the direction of the central axis P. In this case, as shown in FIG. 6, “a ₁ ” is the height of the tapered tapered surface 54 in the region where the molten metal 71 exists in the radial direction centered on the central axis P. In other words, "a ₁ " is the absolute value of the difference between the radius of the upper end of the tapered tapered surface 54, which is centered on the central axis P and coincides with the molten metal surface of the molten metal 71, and the radius of the lower end of the tapered tapered surface 54. is there. Further, "W ₁ " is the maximum inner diameter of the body 50 in the region where the molten metal 71 exists. Further, “L ₁ ” is the length of the tapered tapered surface 54 in the region where the molten metal 71 exists in the direction of the central axis P. In other words, "L ₁ " is the length from the molten metal surface of the molten metal 71 to the lower end of the tapered tapered surface 54 in the direction of the central axis P.

Further, it is desirable to set the lower end of the tapered tapered surface 54, which is the boundary point with the tapered tapered surface 53, at a position 100 mm from the upper end of the body 50 or a position 5 mm to 100 mm from the molten metal surface of the molten metal 71. If the lower end of the tapered tapered surface 54 is too high, the length of the tapered tapered surface 54 is too short, so that the effect of forming the tapered tapered surface 54 into a tapered tapered shape is not sufficiently exhibited. This is because a flaw is formed on the surface at the time of pulling out. However, the surface of the molten metal 71 is preferably located 5 to 80 mm from the upper end of the body 50.

FIG. 7 is a cross-sectional view of the mold 5B which is the second modification.

The mold 5B has a truncated cone-tapered tapered surface 54 located below the opening 51. Further, the inner peripheral surface of the mold 5B includes a cylindrical straight body surface 55 parallel to the central axis P and a tapered tapered surface 53 below the tapered tapered surface 54. A solidifying region for solidifying the molten metal 71 injected into the mold 5 is set on the inner peripheral surface of the mold 5B. The solidification region is set so as to straddle the tapered tapered surface 54 and the straight body surface 55. That is, the molten metal 71 injected into the mold 5B is cooled by the tapered tapered surface 54 and the straight body surface 55 to form the titanium ingot 72.

Even in this case, as in the case of the mold 5A, the occurrence of wrinkles can be prevented by the action of the tapered tapered surface 54. Further, even if a hot water wrinkle is formed and a breakout occurs, the spattered molten metal 71 can be received by the tapered tapered surface 53, and the spattering of the molten metal 71 can be prevented.

Although the molds 5, 5A and 5B are cylindrical, they may have a polygonal column shape such as a quadrangular prism.

By providing the tapered tapered surface 53 on the mold, it is possible to prevent the molten metal 71 from scattering when a breakout occurs. By providing the tapered tapered surface 54 on the mold, it is possible to suppress the occurrence of breakout, and further, it is possible to prevent the molten metal 71 from scattering when the titanium ingot 72 is pulled out from the mold. Below, in order to confirm the effect of the method for producing a titanium ingot when the tapered tapered surface 54 is provided, the casting test shown below was carried out and the result was evaluated.
(1) Melting and casting conditions Raw material: Bricket with a diameter of 100 mm and a length of 200 mm, which is a mixture of sponge / titanium and alloy components.
Mold inner diameter: 650 mm
Mold length: 500 mm
Dissolution amount: 8000 kg
Melting rate: 800 kg / hour Pulling out and pushing up pattern of titanium ingot ・ Repeat pattern of intermittently raising immediately after intermittent pulling out ・ Average pulling out speed: 2 to 20 mm / s
・ Pull-out interval: 1 to 10 mm / time ・ Average push-up speed: 2 to 20 mm / s
-Pushing interval: 0.5 to 5 mm / time Irradiation method of irradiation units 31, 32, 33: Electron beam or plasma hearth 4 size: Width 500 mm x Length 1500 mm x Depth 100 mm
Dissolution method of melting raw materials: Continuous supply of briquettes according to the dissolution rate Irradiation unit 31: 2 Irradiation unit 32: 1 Irradiation unit 33: 1 Projection length of hot water supply port: 5 mm or more and 100 mm or less

Further, in the tests carried out, as the molds of the examples of the present invention and the comparative examples, the mold 5A shown in FIG. 5, the mold 5B shown in FIG. 7, the mold whose inner peripheral surface of the fuselage is parallel to the central axis, and the inner circumference of the fuselage A mold was used in which the entire surface gradually shortened from the upper side to the lower side from the central axis.

(2) Chemical Composition of Titanium Ingots In the following, "%" regarding the chemical composition means "mass%" unless otherwise specified.
In the case of titanium alloy, Al: 4.1 to 7.5%, Fe: 0.1 to 2.1%, V: 2.8 to 5.0%, O: 0.03 to 0.5%, N : 0.005 to 0.2%, C: 0.005 to 0.2%, the balance Ti and impurities are exemplified.

Al is an α-stabilizing element and has the effect of improving Young's modulus and reducing the density. However, if the content is less than 4.1%, the strength cannot be ensured, the density cannot be sufficiently reduced, and the weight cannot be reduced. Further, when the content exceeds 7.5%, Ti ₃ Al is easily generated and becomes brittle. Therefore, the Al content was set to 4.1 to 7.5%.

Fe is a β-stabilizing element, and its strength increases according to the amount of addition, and the fatigue strength improves. However, if the content is less than 0.1%, the increase in strength is small and the effect is not recognized. Further, when the content exceeds 2.1%, segregation during solidification becomes remarkable, and it becomes difficult to eliminate segregation in the process heat treatment step. Therefore, the Fe content was set to 0.1 to 2.1%.

V is a β-stabilizing element and improves cold workability. However, if the content is less than 2.8%, the effect of improving the cold workability is small. If the content exceeds 5.0%, the cost increases because V is a relatively expensive element. Therefore, the V content was set to 2.8 to 5.0%.

O, N, and C are α-stabilizing elements, and the amounts contained as impurities are 0.03 to 0.5% for O, 0.005 to 0.2% for N, and 0.005 to C for C. It is 0.2%. There is a tendency to improve the strength by increasing the content of these elements, but if it exceeds the above range, the ductility of the product will decrease. On the other hand, even if the content is reduced to be less than the above range, the ductility is not improved and the manufacturing cost is increased. Therefore, O was 0.03 to 0.5%, N was 0.005 to 0.2%, and C was 0.005 to 0.2%.

In the case of pure titanium, O: 0.15% or less, Fe: 0.20% or less, N: 0.03% or less, C: 0.08% or less, H: 0.013% or less, and the balance Ti Some are illustrated. If it exceeds the above range, the ductility of the product will decrease. Therefore, the components of each element are within the above range.

(3) The evaluation results are summarized in Table 1.

In Table 1, the mold (I) is a mold having the same shape as the mold 5A shown in FIG. The mold (II) is a mold in which the inner peripheral surface of the fuselage is parallel to the central axis. The mold (III) is a mold in which the entire inner peripheral surface of the fuselage gradually shortens the distance from the central axis from the upper side to the lower side.

When cracks were generated on the surface of the titanium ingot, a sample of 30 mm in the thickness direction and 30 mm in the casting direction of the titanium ingot including the crack was sampled, and the observation surface was mirror-polished. The cracks were observed with an optical microscope, and the depth of the cracks from the surface layer was measured.

In addition, when the titanium ingot was pulled out, it was observed whether or not there was a breakout in which defects such as wrinkles broke and the molten metal inside leaked out.

As shown in Table 1, it can be seen that when the mold has the tapered tapered surface 54, it is possible to reduce the wrinkles and cracks that are derived from the surface of the titanium ingot, and it is possible to suppress breakout. As a result, the tapered surface 53 can prevent the molten metal from scattering when a breakout occurs. Further, since the occurrence of breakout can be suppressed by the tapered tapered surface 54, it is possible to further prevent the molten metal 71 from scattering when the titanium ingot 72 is pulled out from the mold.

According to the present invention, it is possible to prevent the molten metal from scattering when a breakout occurs.

1 Manufacturing equipment 2 Raw material supply unit 4 Hearth 5, 5A, 5B Mold 6 Support base 31, 32, 33 Irradiation unit 50 Body 51 Opening 51A Opening 52, 55 Straight body surface 53 Tapered tapered surface 54 Tapered tapered surface 70 Titanium alloy Raw Material 71 Molten 72 Titanium Ingot

Claims (6)

Including a casting step of injecting a molten metal containing titanium into a mold to form a titanium ingot.
The mold has a bottomless tubular body and
The upper end of the fuselage includes an opening for receiving the molten metal.
The inner peripheral surface of the fuselage includes a tapered tapered surface located below the position of the opening.
A method for producing a titanium ingot, wherein the tapered tapered surface is longer in distance from the central axis of the body as it advances downward. The inner peripheral surface of the fuselage includes a tapered tapered surface located below the opening and above the tapered taper portion.
The tapered surface has a shorter distance from the central axis of the fuselage as it advances downward.
The method for producing a titanium ingot according to claim 1. The method for producing a titanium ingot according to claim 2, wherein the surface of the molten metal in the mold is in contact with the tapered surface. A solidification region for solidifying the molten metal is set on the inner peripheral surface of the body.
The method for producing a titanium ingot according to claim 3, wherein the solidified region straddles the tapered tapered surface and the tapered tapered surface. The titanium ingot according to any one of claims 1 to 4, wherein a gap is formed between the titanium ingot and the tapered tapered surface at least at the lower end of the tapered tapered surface. Production method. With a bottomless tubular fuselage,
The upper end of the fuselage includes an opening for receiving a molten metal containing titanium.
The inner peripheral surface of the fuselage includes a tapered tapered surface located below the position of the opening.
A titanium ingot manufacturing mold in which the tapered surface is increased in distance from the central axis of the body as it advances downward.

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