JPH0681069A - Production of refractory metal material excellent in workability and sheet therefrom - Google Patents

Abstract

(57) [Abstract] [Purpose] To obtain a material having high workability such as high melting point metal such as Mo, W, Ta, Nb, and to manufacture a thin plate thereof. For example, a Mo thin plate capable of deep drawing (Erichsen value of 4 mm or more) used for manufacturing cathode tubes of CRTs,
It enables production without the need to use extremely high-purity materials and without suffering from annealing brittleness. [Composition] Mo, W, Ta, N with a purity of three or more
In b, Re is 5% or less by weight, preferably 0.5 to 3
%, More preferably 1-2%, rolled into a thin plate, and annealed by heating to a temperature equal to or higher than the recrystallization temperature. Re
In addition to 1% or less of B, preferably 0.01 to 0.5%
If added, even better results are obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a refractory metal material excellent in workability, specifically, Mo, which can be rolled or deep-drawn.
The present invention relates to W, Ta, and Nb materials and methods for manufacturing thin plates thereof.

[0002]

2. Description of the Related Art Refractory metals such as Mo, W, Ta and Nb should be able to be used for various purposes by utilizing their characteristics, but it is difficult to process them into products, which imposes restrictions. There are many. For example, a Mo tube used as a cathode part of a CRT is manufactured by deep drawing a Mo thin plate. However, since Mo is a metal with poor workability, it is not easy to obtain a Mo thin plate capable of deep drawing.

One of the inventors of the present invention first noticed the "cross-rolling" technique, which is a continuous rolling but can give a thin material having small anisotropy, and applied it to the production of a Mo thin plate. As a result of the intentional research, a high-purity Mo material of five-nine or more, preferably six-nine or more produced by electron beam melting is used, and the material is roll-rolled once to be subjected to a cross-rolling process. According to the above, it was found that a Mo thin plate having a required deep drawability can be obtained, and it has already been disclosed (JP-A-3-
291101).

Although the above method is effective, it may be difficult to obtain Mo having a purity of five nines or six nines, and a high purity product is naturally expensive.
Further, when annealing is performed to facilitate deep drawing, the workability is often impaired due to annealing brittleness.

[0005] The applicant who studied for a solution to this new problem found that Mo having a purity of 99.9% or more,
It was found that adding 0.2% or less of B to W, Ta or Nb improves the workability of these metals, and also proposed this (Japanese Patent Application No. 3-218639).

As a result of further development, it is known that the addition of an appropriate amount of Re is also effective for improving the workability of the above refractory metal, and that it is more effective to add Re and B together. It was

[0007]

The object of the present invention is to solve the long-standing problems concerning rolling and deep drawing of high melting point metals such as Mo into thin plates by utilizing the above new knowledge. It is to provide a material having a workability that is capable of deep drawing even when a refractory metal having a low purity is used as a raw material, and a method for manufacturing such a thin plate. .

[0008]

The refractory metal material excellent in workability according to the present invention is basically 5% or less by weight, preferably 5% or less by weight of Mo, W, Ta or Nb having a purity of three-nine or higher. Is 0.5 to 3%, more preferably 1 to 2%
Of Re is added.

In addition to the above-mentioned basic alloy composition, the refractory metal material of the present invention excellent in workability further contains B: 1% or less, preferably 0.01 to 0.5%. Good.

The method for producing a high-melting-point metal sheet excellent in workability according to the present invention is 5% or less Re or 5% of Mo, W, Ta or Nb having a purity of three or more as described above.
It consists of rolling a refractory metal material obtained by adding Re and 1.0% or less of B into a thin plate, and subjecting this thin plate to an annealing treatment of heating it to a temperature of a recrystallization temperature or higher. Although the thickness of the thin plate obtained by rolling is arbitrary, it is usually appropriate to set the thickness to about 50 to 250 μm depending on the application.

Annealing is performed at a temperature of 500 ° C. or higher and naturally has a melting point (Mo: 2610 ° C., W: 3370 ° C., Ta: 2996).
℃, Nb: 2468 ℃) heating to a lower temperature 2
It is carried out under the condition of 1 minute to 1 hour. Therefore, as described later, high temperature annealing is possible.

[0012] In rolling into a thin plate, W cannot be thinned all at once with a high reduction rate, and therefore reduction of about 10% and annealing must be repeated until a thin plate with a desired thickness is reached. Mo, Ta and Nb can be rolled without such restrictions.

[0013]

It has been observed that when Re is added to Mo, W, Ta and Nb, the recrystallization temperature (which means the annealing temperature at which the recrystallized grain size becomes a size measurable by an optical microscope) increases. Accordingly, the annealing embrittlement start temperature shifts to the high temperature side, and the annealing embrittlement is suppressed. This effect is Re0.5
%, The content becomes clear, and the content increases up to about 2% as the amount of addition increases. If it exceeds 5%, the workability is deteriorated and it must be avoided. On the other hand, the effect of adding B to Mo or the like is that, as described above with respect to the invention, B refines the crystal grains to suppress annealing brittleness, and exists in the grain boundaries to increase the strength of the grain boundaries. As a result, it is considered that deep drawability is brought about. By adding B together with Re, the effect of B for improving the annealing brittleness of Mo and the like can be obtained together with the effect of Re addition. The effect can be said to be synergistic in view of the data described later. B
The effect of addition is recognized at the addition of about 0.01%, 0.5
%, It increases to inside and outside, and when it exceeds 1.0%, it decreases on the contrary.

Annealing is performed by heating above the recrystallization temperature as described above. Annealing embrittlement cannot be overcome by conventional strain relief annealing and softening annealing, that is, annealing that is performed below the recrystallization temperature. Generally, a suitable temperature is approximately 130
It is 0 ° C.

[0015]

Example 1 Commercially available M with a guaranteed purity of three nines
o and melted by electron beam melting, M
o Single (hereinafter referred to as “M material”), Mo containing 1.9% Re
1.9% added to Mo (“MR material”) and Mo
With Re and 0.05% B ("MRB
Material ”) was prepared.

A test piece was prepared from the ingot of each material, and was placed in vacuum at 600 ° C, 700 ° C, 900 ° C, 1100 ° C.
A vacuum annealing treatment of heating at 1300 ° C. or 1500 ° C. for 2 hours was performed.

The surface of the test piece was polished, and intergranular corrosion was performed by electrolytic corrosion in a 10% oxalic acid aqueous solution to observe the structure. The crystal grain size is measured by the line segment method. The relationship between the crystal grain size and the annealing temperature is as shown in FIG. 1, and the effect of suppressing the crystal grain coarsening by the addition of Re is clear.

Next, the Vickers hardness was measured using a micro hardness meter (load: 500 gf). The results are shown in Figure 2.
In the figure, the arrow indicates the annealing temperature at which the recrystallized grain size can be measured by an optical microscope. It can be seen that the hardness decreases from a low temperature, and the recovery of the processed structure and the subsequent recrystallization cause a rapid softening.

The results of the tensile test are shown in FIGS. 3 and 4.
FIG. 3, which shows the relationship between the tensile strength and the annealing temperature, shows that the curve in which the tensile strength decreases as the annealing temperature rises moves to the high temperature side due to the addition of Re or Re + B. FIG. 4, which shows the relationship between the elongation and the annealing temperature, shows that the annealing temperature at which the relative decrease in the elongation begins is Re
Further, it is shown that addition of Re + B moves to a higher temperature side, that is, the temperature at which annealing embrittlement occurs becomes higher, and addition of Re + B causes higher elongation and improves workability of the material.

[0020]

Example 2 Various amounts of Re were added to Mo having a purity of 99.9% or more and dissolved in an electron beam.

The obtained ingot was hot-rolled into a thin plate having a thickness of 0.5 mm, which was cold-rolled to a thickness of 15 mm.
After making a sheet of 0 μm, it is heated to 1300 ° C. in vacuum for 30 minutes.
Annealing was performed for heating for 1 minute.

A drawing test was conducted to examine the workability of the annealed material. The change in Erichsen value with Re addition amount is shown in FIG. From this result, it is understood that the optimum addition amount of Re to Mo is 1 to 2%.

[0023]

According to the present invention, a refractory metal material having a high workability can be obtained using Mo, W, Ta, Nb having a purity of three nines as a raw material. This material exhibits workability that allows it to be rolled into a thin plate of any thickness, the manufactured thin plate has sufficient deep drawability, and there is no concern about annealing brittleness. A high-melting point metal having a purity of about three nines is easily available as a powder sintered product is commercially available, and it is not necessary to repeat the electron beam melting to obtain an extremely high purity at a high cost. Therefore, a thin plate having high workability can be provided at low cost.

[Brief description of drawings]

FIG. 1 is a graph showing the data of the example of the present invention, showing the average crystal grain size of the M material and the MR material in relation to the annealing temperature.

FIG. 2 is also data of an embodiment of the present invention, in which M
The graph which showed the Vickers hardness of the material, MR material, and MRB material with respect to annealing temperature.

FIG. 3 is also data of an example of the present invention, in which M
The graph which showed the tensile strength of the material, MR material, and MRB material with respect to annealing temperature.

FIG. 4 is also data of an embodiment of the present invention, in which M
The graph which showed the elongation of the material, MR material, and MRB material with relation to annealing temperature.

FIG. 5 is data of another embodiment of the present invention, wherein Mo
The graph which showed the Erichsen value of the material which added Re to 2nd in relation with the Re addition amount.

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Claims (3)

[Claims] 1. Mo having a purity of three-nine or more,
A refractory metal material having excellent workability, which is obtained by adding 5% or less by weight of Re to W, Ta or Nb. 2. The refractory metal material according to claim 1, further containing B: 1% or less in addition to Re. 3. A method for producing a high-melting-point metal thin plate, which comprises rolling the high-melting-point metal material according to claim 1 or 2 into a thin plate, heating the obtained thin plate to a temperature equal to or higher than a recrystallization temperature, and performing annealing treatment. .