JPS63177955A - Method for producing titanium alloy cast block - Google Patents

Abstract

PURPOSE:To execute addition of a little quantity of a component under high yield by using green compact blending additional element to sponge titanium or powdered titanium as core material, melting by heating cylindrical body winding a thin sheet of main element on the outside from one end, and solidifying by dropping the drips into the mold. CONSTITUTION:The green compact 1 blending a little quantity of the additional element to the sponge titanium, etc., is made to the core material, and melting raw material 4 is made by winding alternately Ti-made thin sheet 2 and Nb- made thin sheet 3 on this core material. The melting raw material 4 arranged in a vacuum room 5 of electron beam furnace is irradiated by electron beam through an electron gun 6 from the lower part thereof while rotating and descending the raw material. In this way, Ti, etc., in the material 4 is melted without any loss, and is made to the drip and solidified in the metal pool 8 in the water cooled copper mold 7, to draw from the mold 7 as the Nb-Ti series alloy cast block 9. Thus, the material having high melting point is not remained to melt and Nb-Ti series alloy casting block for super conductivity material having uniform composition is stably produced at comparatively few number of process.

Description

[Detailed Description of the Invention] <Industrial Application Field> This invention provides a titanium alloy that can be efficiently implemented with a high yield by adding small amounts of components other than the main elements, and that can stably obtain products with a uniform component distribution. The present invention relates to a method for manufacturing an alloy ingot.

<Prior art and its problems> In recent years, with the development of superconducting application technology, the demand for superconducting materials such as Nb-Ti alloys has increased rapidly. Since it is impossible to manufacture using normal melting methods, in general, melting materials such as consumable electrodes are melted using an arc or energy beam (electron beam, plasma beam, etc.) as a heating source, and the resulting droplets are placed below. The "drip melting method" is used to continuously drip and mix into a water-cooled copper mold and solidify in layers. In order to produce more homogeneous alloys, various efforts have been made to date, particularly in the form of the melted material.

However, the methods currently in use as practical methods can be roughly divided into two methods: vacuum arc melting of a consumable electrode formed by mixing and compressing powders of the various metals that make up the alloy;
In reality, the current situation has been focused on two methods: vacuum arc melting of a composite consumable electrode made by laminating plates of each metal constituting the alloy alternately (Japanese Patent Publication No. 55-6089).

However, even if these practical measures are adopted, (a) melting of metals on the high melting point side tends to leave residue;
b) Problems such as impurity contamination caused by melting preparation work, etc. (poor stability of C1 melting work) remain unresolved, and it is extremely difficult to stably produce the desired high-quality homogeneous alloy. It was difficult.

Therefore, based on the above-mentioned situation, the inventors of the present invention first stacked thin plates made of each metal constituting the alloy, wound them into a multilayer cylinder, and drip-melted this as a melting material. proposed a method (Japanese Patent Application Laid-Open No. 1974-1974)
No. 3). According to the above-mentioned method proposed earlier, there is no residual melt of high melting point components, there is little contamination by impurities, the melted material is easy to prepare, and a sufficiently homogeneous ingot can be obtained under stable melting conditions. Therefore, this method could be called an epoch-making method for producing alloys made of high-melting point metals.

However, recently, there has been a demand for alloys made by adding and adjusting small amounts of elements such as W, Mo, or Si to alloys of high melting point metals such as NbTi alloys.

Therefore, the present inventors attempted to manufacture such an alloy by the above-mentioned method proposed earlier, but in this case, the amount of added W, Mo, or Si, etc. was extremely small, and due to the melting point, it was difficult to manufacture the alloy sufficiently. It has become clear that in order to ensure uniformity, it is necessary to prepare a thin plate material of each main component metal or a core material around which it is wrapped, which already contains a predetermined small amount of additive elements. However, even if you try to use commercially available plate materials containing the above-mentioned small amounts of elements, there is a limit when the number of additives varies, and it is also necessary to melt an ingot to have a predetermined composition system in advance to produce plates or rods. In practice, it is difficult to process ingots into plates or bars because the cost burden is too great to manufacture the material, and there is a possibility that the alloy composition will be based on an alloy composition that we have no experience in manufacturing. It turns out that there are problems that cannot be avoided.

Means for Solving the Problems> From the above-mentioned viewpoints, the present inventors have discovered that the melting of high melting point components does not cause contamination due to residue or impurities, and that
Not only does it make it easier to create melted materials and ensure the stability of the melting process, but it also makes it possible to add small amounts of components other than the main components efficiently with a high addition yield, and to ensure uniform distribution within the ingot. In order to provide a means of manufacturing titanium alloy ingots, we conducted research through repeated experiments and studies, and found that
[First, a compact is made by blending sponge titanium or powdered titanium with the required amount of small amounts of added elements, and the surrounding area is coated with the method previously proposed (Japanese Patent Application Laid-Open No. 61-1989).
No. 743), if thin plates of the main component metals are wound alternately to create a cylindrical melted material and this is drip melted, the addition yield of small amounts of alloying elements will be approximately 100%.
%, and the component distribution in the resulting ingot is stable and almost uniform.''

This invention was made based on the above findings, and uses a compacted powder body made of sponge titanium or powdered titanium mixed with a small amount of added elements other than the main elements (for example, W, Mo, Si, etc.) as a core material. A thin plate of main elements (Ti and Nb, etc.) is wrapped around the outside to create a cylindrical melted material, and this melted material is continuously heated and melted from one end using a drip method etc., and the droplets are poured into the mold. By dropping the titanium alloy ingot into solidification, it is possible to stably produce a homogeneous titanium alloy ingot while ensuring a high addition yield of small amounts of elements.

FIG. 1 is a schematic diagram showing an example of a melted material used when melting a Nb-Ti alloy containing a small amount of additive elements according to the method of the present invention. A perspective view is shown in FIG. (compact), and several pieces of the green compact (compact) 1 are connected by force q displacement etc. to form the core material of the melted material.The melted material 4 is then
It is constructed by alternately winding thin plates 2 made of i and thin plates 3 made of Nb.

When the melted material 4 is created in such a form, the melted material 4 is either vacuum arc melted as a consumable electrode or melted in an energy beam furnace or the like to form a Nb-Ti alloy. The second example shows how a Nb-Ti base metal ingot is manufactured by continuously melting and solidifying in a furnace.
This is shown schematically in the figure.

In FIG. 2, a melted material 4 placed in a vacuum chamber 5 of an electron beam furnace is irradiated with an electron beam from an electron gun 6 from its lower end while being slowly rotated and lowered. As a result, the Ti, etc. in the melted material 4 is alloyed with other elements, and the melt is sequentially melted from the bottom without leaving any residue or escaping small amounts of elements, forming droplets in the water-cooled copper mold 7. The receiver is fixed in a metal pool 8 and solidified, and is continuously pulled out from the water-cooled copper mold 7 as an Nb-Ti alloy ingot 9.

As described above, the method of the present invention does not require the step of manufacturing bars or plates containing a small amount of a specified component in advance, and can add a small amount of the component simultaneously with the melting of the main component in an extremely stable and high-yield manner. <It can be implemented.

Note that it is preferable to use the alloy ingot 9 obtained as described above as a secondary melting material and remelt it by the same means or other melting means in order to obtain a more homogeneous alloy.

Next, the present invention will be explained by examples.

<Example> Example 1 Ingredient composition as shown in Table 1 (including 0.5% Mo)
An Nb-Ti alloy was produced with the aim of achieving this goal.

When melting the alloy shown in Table 1, first, sponge titanium of 0.5 inch 20 meshes and powdered wire Mo of 200 μm or less are mixed to a predetermined concentration, and this is compression molded to form a cylindrical compact. After connecting multiple pieces by welding to form a core material of a predetermined length, a pure Nb plate (0.3 thickness) was obtained.
and pure Ti plate (0.3 dragon thickness) alternately,
A melted material as shown in the figure was prepared. Table 2 shows the compositions of the pure Nb plate, pure Ti plate, and titanium sponge used at this time.

Table 2 The diameter of the compact core material, the thickness of the pure Nb plate, and the thickness of the pure Ti plate were adjusted according to the target component composition shown in Table 1.

Furthermore, for comparison, N of 150 meshes or less as in the past
B powder, sponge titanium with a particle size of A inch or less, and MO powder with a particle size of 100 mesh or less are uniformly mixed and compression molded,
A cylindrical melted material (briquette) was created.

Next, using each of the melted materials created as described above as a consumable electrode, vacuum arc melting is performed in the usual manner under the conditions shown in Table 3, and the generated droplets are sequentially received in a water-cooled copper mold and solidified. Nb-Ti based alloy ingots were continuously produced. In addition, all dissolutions were carried out up to the secondary dissolution.

Table 3 A comparison of the component distribution in the center of the secondary ingot of the Nb-Ti alloy thus obtained is shown in FIG.

As is clear from the results shown in Figure 3, when using a melted material made by compression molding the powder of each component as in the past, the Mo concentration is almost close to the target value, but the Nb concentration distribution is It can be seen that, while there is large variation overall, when the melted material according to the present invention is used, all components have a uniform distribution. In addition, when the structure of the central axis surface of the ingot obtained by the conventional method was investigated, a large amount of unmelted Nb was found, and it was confirmed that this was the cause of the component variation.

In addition, only the component distribution of the secondary ingot was introduced here;
- It goes without saying that the ingot produced by the method of the present invention showed a more uniform component distribution than the conventional method.

Example 2 In this example, the A/! component composition (including 2.0% W) as shown in Table 4 was targeted. - A Ti alloy was melted.

When melting the alloy shown in Table 4, first, sponge titanium of 20 meshes or less and powder wire W of 100 μm or less are mixed to a predetermined concentration, and this is compression molded to obtain a cylindrical compact. After connecting multiple pieces by welding to make a core material of a predetermined length, pure I plate (0.4 m thick) and pure Ti plate (0.4 m thick)
, 3111 thickness) were wound alternately to create a melted material as shown in FIG. Table 5 shows the compositions of the pure I plate, pure Ti plate, and titanium sponge used at this time.

Note) ACTi and W are expressed in [%], and O, N, H and Fe are expressed in (ppm).

The diameter of the compact core material, the winding thickness of the pure Al plate, and the winding thickness of the pure Ti plate were each adjusted according to the target component composition shown in Table 4.

Furthermore, for comparison, instead of the pure Ti plate mentioned above, a T plate manufactured by rolling from a Ti-W master alloy ingot with a predetermined W concentration was used.
Using an i-W master alloy plate, this and a pure Al plate were alternately wound around a core material made of pure Ti to obtain a melted material.

Next, vacuum arc melting is performed in the usual manner under the conditions shown in Table 3 using each of the melted materials created as described above as a consumable electrode, and the generated droplets are sequentially received in a water-cooled copper mold and solidified. In this way, Aj2-Ti alloy ingots were continuously manufactured. In addition, all dissolutions were carried out up to the secondary dissolution.

FIG. 4 shows a comparison of the component distribution in the center of the secondary ingot of the Aβ-Ti alloy thus obtained.

As is clear from the results shown in FIG. 4, A/! was melted according to the method of the present invention! -The Ti-based alloy ingot requires fewer steps (-thin melting, first-second melting) compared to the comparative example, which involves multiple steps of [melting of the master alloy - rolling, first melting, and second melting]. Nevertheless, it can be seen that the distribution of Aj2 and W is on the same level as the ingot obtained in the comparative example.

<Summary of Effects> As explained above, according to the present invention, high melting point components are dissolved without leaving any residue, and addition of small amounts of components can be carried out efficiently with high addition yields, and relatively easily. This brings about industrially useful effects, such as making it possible to stably produce titanium alloy ingots with uniform composition in a small number of steps.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing an example of a melting material used in the method of the present invention, FIG. 1(a) is a perspective view thereof, and FIG. 1(b) is a longitudinal cross-sectional view thereof. FIG. 2 is a schematic diagram showing how a titanium alloy ingot is manufactured by continuously melting and solidifying the melted material according to the present invention in an electron beam furnace, and FIG. , a graph showing the concentration and distribution of component elements in the Nb-Ti alloy ingot obtained in Example 1, and FIG. 4 shows the concentration and distribution of component elements in the Ag-Ti alloy ingot obtained in Example 2. This is a graph showing. In the drawings, 1... Green compact (compact), 2... Ti thin plate,
3... Nb thin plate, 4... Melting material, 5...
...Vacuum chamber, 6.Electron gun, 7.Water-cooled copper mold, 8.Metal pool, 9.Alloy ingot,
10...Electron beam.

Claims (1)

[Claims] A cylindrical body made of sponge titanium or powdered titanium mixed with additive elements other than the main elements is used as the core material, and a thin plate of the main element is wrapped around the outside of the core material.The cylinder is continuously heated and melted from one end. , a method for producing a titanium alloy ingot, characterized in that the droplets are allowed to fall into a mold and solidify.