JPH03277751A - Production of electrode for remelting - Google Patents

Abstract

PURPOSE:To prevent the occurrence of a disadvantage of the falling of a part of an electrode by applying stress relief heat treatment to an ingot which is to be an electrode used in a state preheated by means of a remelting furnace and is prepared by applying primary melting to raw materials in the production of an alloy by a duplex melting method. CONSTITUTION:For example, in a secondary melting device having a water cooled mold 1, an electrode 2 for remelting is melted by means of an arc produced from itself in a state preheated to 200-800 deg.C. By the above melting, a final product 3 in which, e.g. the reduction of nonmetallic inclusions is attained can be obtained. The electrode 2 is an ingot prepared by subjecting blended raw materials to primary melting and to casting, and stress relief heat treatment is applied to this ingot. By this method, the residual stress of the ingot after casting is practically reduced to zero. Accordingly, the electrode 2 capable of sufficiently withstanding thermal stress at the time of melting can be obtained, and the occurrence of the falling of a part of the end of the electrode 2 can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention 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 melting furnace in a double melting process for producing an alloy. It is something.

[Prior Art] In recent years, melting methods for manufacturing alloys have been developed with the aim of reducing segregation, improving hot workability, and reducing nonmetallic inclusions.
A double dissolution method is adopted.

In this double melting method, the blended raw materials are first heated in a vacuum induction furnace.
After primary melting in an arc furnace, atmospheric high frequency induction furnace, etc., an ingot is produced, and this ingot is used as a remelting electrode to be remelted in a vacuum arc melting furnace, electroslab melting furnace, etc. to produce the final product ingot. be.

The remelting electrode used in the double melting method is manufactured by simply casting after primary melting as described above.

"Problem to be Solved by the Invention" However, when a remelting electrode is made by casting stellite, for example, a part of the remelting electrode falls off during the remelting process, and as a result, remelting is not possible. In other words, in the electrode used for remelting, a large thermal stress occurs between the molten part and the solid part that has slightly formed from it.In this case, the electrode for remelting If it is highly ductile, there will be no problem, but if the electrode made of the aforementioned stellite is simply cast, the ductility of the electrode is extremely low (elongation is about 0%), so the thermal stress of remelting can cause the electrode to crack. There was a problem that some of them would fall off.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a method for manufacturing a remelting electrode that can sufficiently withstand thermal stress.

1. Means for Solving the Problems] In order to achieve the above object, the present invention, in producing an alloy using a double melting method, preheats it to 200°C to 800°C in a remelting furnace in the double melting process. This is a manufacturing method for the remelting electrode used, in which an ingot to be used as an electrode is manufactured after primary melting of blended raw materials, and this ingot is subjected to a heat treatment to remove strain.

[Function] In the present invention, residual stress within the ingot is removed by strain relief heat treatment. Furthermore, the temperature is 200° when remelted.
Since the ingot is preheated to 800°C to 800°C, the ductility of the ingot during use is improved. Furthermore, this preheating also reduces the temperature gradient of the ingot, thereby reducing thermal stress.

Therefore, due to the reduction in residual stress, the improvement in ductility, and the reduction in thermal stress, an ingot that can sufficiently handle thermal stress is produced.

[Example-Co Examples of the present invention will be described below.

FIG. 1 is a diagram showing a vacuum arc melting furnace, and shows an apparatus for secondary melting in a double melting method.

In this figure, 1 is a water-cooled mold, and 2 is a remelting electrode. This remelting electrode 2 is made of stellite (components: 1% carbon, 4% tungsten, 30% chromium, residual cobalt), and is heated to 200°C to 800°C. It is melted by the arc emitted from the By melting the remelting electrode 2, a final product 3 of stellite with reduced nonmetallic inclusions is obtained.

The remelting electrode 2 is used for the primary melting (
However, the device for second melting is not shown) and subsequent heat treatment.

That is, in order to manufacture the remelting electrode 2, first, the blended raw materials are primarily melted and an ingot is cast.

Thereafter, this ingot is subjected to strain relief heat treatment.

In this case, the heat treatment is 800℃ for the above stellite.
This is done by holding at a temperature of ~1250°C for 1 to 3 hours.

As a result, residual stress in the ingot after casting becomes almost zero.

The remelting electrode 2 manufactured as described above is preheated to 200°C to 800°C in a vacuum arc melting furnace and is melted by an arc generated by itself to form a final product 3.
become. At this time, the ductility of the remelting electrode 2 is improved by preheating (elongation becomes about 15%), and the temperature gradient between the melting start part and the part immediately on the proximal end side becomes smaller, and the heat in that part becomes smaller. Stress is reduced.

Therefore, due to the reduction in residual stress, the improvement in ductility, and the reduction in thermal stress, a remelting electrode 2 can be obtained that can sufficiently handle the thermal stress during melting, and a part of the tip of the remelting electrode 2 is This can prevent the problem of falling off.

[Effects of the Invention] As explained above, according to the present invention, in alloy manufacturing using the double melting method, the remelting furnace used in the double melting process is preheated to 200°C to 800°C. This method of manufacturing electrodes for melting involves first melting the blended raw materials, then manufacturing an ingot that will become the electrode, and then subjecting this ingot to heat treatment to remove distortion. Stress can be reduced, and the ductility of the ingot during melting can be improved and thermal stress can be reduced.

Therefore, it is possible to obtain a remelting electrode that can sufficiently withstand thermal stress during melting, and thereby it is possible to prevent a problem in which a part of the tip of the remelting electrode falls off.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a vacuum arc melting furnace shown as an embodiment of the present invention. 1...Water-cooled mold, 2...Remelting electrode, 3...Final product.

Claims (1)

[Claims] A method for manufacturing a remelting electrode that is preheated to 200°C to 800°C in a remelting furnace in the double melting process in alloy manufacturing using the double melting method, and the method involves the primary melting of mixed raw materials. After that, we manufacture ingots that will become electrodes.
A method for producing an electrode for remelting, which comprises subjecting the ingot to heat treatment to remove strain.