JPS61133333A - Production of electrode for remelting - Google Patents

Abstract

PURPOSE:To produce an electrode for remelting which obviates the generation of a crack and partial dislodgment in the stage of remelting by subjecting a compounded raw material to primary melting then producing an ingot and subjecting the ingot to hot forging followed by a stress relief heat treatment. CONSTITUTION:The compounded raw material is subjected to the primary melting by a vacuum induction furnace, arc furnace, atm. high-frequency induc tion furnace, etc., and thereafter the ingot thereof is produced in a process for production of the electrode to be used for a remelting furnace such as vac uum arc melting furnace and electroslag melting furnace in a double melting stage in production of the alloy. The ingot is then subjected to a hot forging treatment to change the cast structure of the ingot to the forged structure by which the ductility thereof is increased. The ingot after the forging treatment is then subjected to the stress relief heat treatment to improve further the ductility. The electrode for remelting which prevents the crack corresponding to the thermal stress in the stage of remelting and the consequent dislodgment thereof is obtd.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a method for manufacturing an electrode used in a remelting furnace such as a vacuum arc melting furnace or an electroslag 1ejS furnace in a double melting process for producing an alloy. It is something.

[Conventional technology]

In recent years, as a 15'ps method for manufacturing alloys, the two-tfi solution method has been adopted for the purpose of reducing segregation, improving hot workability, and reducing nonmetallic inclusions. This double melting method involves first melting the blended raw materials in a vacuum induction furnace, arc furnace, atmospheric high-frequency induction furnace, etc., then producing an ingot, which is then used as an electrode to melt the raw materials in a vacuum arc melting furnace, electroslag overflow furnace, etc. etc. to produce the final product ingot. By the way, the remelting electrode used in the double melting method has been manufactured by simply casting after the primary f6 melting as described above.

[Problems to be solved by this invention] High carbon cobalt alloy (components: 1% carbon, 4% tungsten, 3% chromium)
When an electrode is made by casting 0% cobalt (cobalt residue), there is a problem in that part of the electrode is removed during the re-melting process, making it impossible to re-melt it. That is, in the electrode used for remelting, a large temperature difference occurs between the bath melting portion and the solid portion slightly separated therefrom, and this temperature difference generates a large thermal stress between them. In this case, there is no problem if the electrode is highly ductile, but if the electrode is simply cast from the above-mentioned high carbon cobalt alloy, the ductility of the electrode is extremely low. For this reason, there was a problem in that the electrodes cracked due to thermal stress during remelting, and a portion of the cracks fell off.

[Means for solving problems]

In this invention, as a means to solve the above-mentioned problems, an ingot is manufactured after first melting the blended raw materials, and after hot forging this ingot, a heat treatment for strain relief is performed.

〔Example〕

Examples of the present invention will be described below. In this embodiment, the steps of hot forging treatment and strain relief heat treatment are added to the ingot produced after the secondary bath melting in the double mackerel melting method shown in the conventional example.

In the method of this invention as well, first the blended ingredients.

Although the process of first melting the material and producing an ingot is the same as in the conventional example, the method of the present invention further includes the following steps. That is, first, the ingot is subjected to hot forging treatment. The purpose of this hot forging treatment is to change the cast structure of the ingot to a forged structure and increase the ductility of the ingot. In this case, the forging ratio is determined depending on the type of alloy; for example, in the case of the above-mentioned high carbon cobalt alloy, the forging ratio is the minimum; 1. Set to about IB.

Next, the hot forged product is subjected to strain relief heat treatment for the purpose of further increasing ductility. The heat treatment temperature in this case is appropriately determined depending on the type of alloy. For example, in the case of the above-mentioned high carbon cobalt alloy, the temperature is set at 1000°C to 1250°C.

The remelting electrode manufactured by the above process is
For example, in the high carbon cobalt alloy mentioned above, the elongation of the ingot after hot forging and strain relief heat treatment is about 7%, whereas the elongation of the ingot after hot forging and strain relief heat treatment is about 7%. become. Therefore, this remelting electrode can sufficiently cope with the thermal stress generated in the four electrodes during remelting, and can therefore prevent cracking of the electrodes and the accompanying deactivation.

〔Effect of the invention〕

As explained above, according to the method for manufacturing a remelting electrode of the present invention, an ingot is manufactured after primary melting of the blended raw materials, and this ingot is hot forged, and then subjected to strain relief heat treatment to be remelted. Since we started manufacturing electrodes for melting, we were able to increase the ductility of this electrode for remelting.
Therefore, it is possible to prevent cracks from occurring in the remelting electrode due to thermal stress during remelting, and it is possible to prevent part of the electrode from coming off due to this.

Claims (1)

[Claims] A method for manufacturing electrodes used in remelting furnaces such as vacuum arc melting furnaces and electroslag melting furnaces, in which an ingot is manufactured after primary melting of blended raw materials, and after hot forging this ingot, straining is performed. A method for producing an electrode for remelting, which comprises performing a heat treatment.