JP2009097073A - Method for manufacturing consumable electrode for remelting, and consumable electrode for remelting - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing a consumable electrode for remelting with which the improvement of the manufacturing work efficiency is obtained and the generation of trouble at the manufacturing time is prevented and the large type consumable electrode can be manufactured without generating a chipping-off. <P>SOLUTION: When the consumable electrode 1 for remelting, composed of precipitation hardening type high nickel alloy exceeding 30 mass% content of the nickel and exceeding 2.0% of the total content of aluminum, titanium, niobium and tantalum; to the precipitation hardening type high nickel alloy formed to the shape of the consumable electrode for remelting, a soaking treatment is applied at the lower temperature than the temperature making the solid-solution, desirably 850-950°C for 10-100 hr. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a method for producing a consumable electrode used for vacuum arc remelting (VAR) and electroslag remelting (ESR) and a remelting consumable electrode, and in particular, the nickel content exceeds 30% by mass and Remelting consumable electrode manufacturing method and remelting consumable electrode used when producing a remelting consumable electrode comprising a precipitation hardening type high nickel alloy having a total content of aluminum, titanium and niobium exceeding 2.0 mass% It is about.

  In the remelting consumable electrode composed of the above precipitation hardening type high nickel alloy, if an attempt is made to simply increase the size, the number of solidified segregation points during electrode casting increases and the brittle phase increases. There is a possibility that a defect due to cracking (a phenomenon in which a part of the electrode falls into the metal pool) may occur, resulting in a quality defect such as freckle, white spot or slag entrainment in the steel ingot product. It has been known.

For this reason, the diameter and weight of the re-dissolving consumable electrode are kept small, for example, the diameter is kept to 300 mm or less and the weight is kept to 2000 kg or less so as not to cause a loss due to an increase in the embrittlement phase. Therefore, it cannot be said that the re-dissolution efficiency is high, and the yield is also poor.
Therefore, recently, in order to improve the re-dissolution efficiency and the yield, by performing soaking at a temperature not lower than 1100 ° C. and not higher than the melting point, the intermetallic compound in the electrode is made into a solid solution, thereby causing a defect. Attempts have been made to produce large reconstituted consumable electrodes (see, for example, Patent Document 1).
Patent No. 3606404

  However, in the above-described conventional method for producing a consumable electrode, the intermetallic compound in the electrode is made into a solid solution in order to eliminate the loss due to the increase in the embrittlement phase, and therefore the step of recooling Therefore, there is a problem that the work efficiency is low by that amount, and there is a concern that a stress difference may occur during recooling and there is a concern that defects such as cracks may occur. It has been a conventional problem to be solved.

  The present invention has been made by paying attention to the above-described conventional problems, and it is possible to improve the manufacturing work efficiency and prevent the occurrence of defects during manufacturing. An object of the present invention is to provide a remelting consumable electrode manufacturing method and a remelting consumable electrode capable of producing a remelting consumable electrode that does not occur.

  The method for manufacturing a remelting consumable electrode according to claim 1 of the present invention is a precipitation hardening in which the nickel content exceeds 30% by mass and the total content of aluminum, titanium, niobium and tantalum exceeds 2.0% by mass. When producing a remelting consumable electrode made of type high nickel alloy, a soaking treatment at a temperature lower than the solid solution temperature is applied to the precipitation hardened high nickel alloy formed into the shape of the remelting consumable electrode for 10 hours. The present invention is characterized in that it is configured as described above, and this method for manufacturing a reconsumable consumable electrode is used as a means for solving the above-described conventional problems.

Further, in the method for producing a remelting consumable electrode according to claim 2 of the present invention, a soaking process at 700 to 950 ° C. is performed for 10 hours or more, and the remelting consumable electrode according to claim 3 of the present invention. In this manufacturing method, a soaking process at 850 to 950 ° C. is performed for 10 to 100 hours.
Examples of the precipitation hardening type high nickel alloy used in the manufacturing method of the remelting consumable electrode of the present invention include Inconel 718, Inconel X-750, Inconel 751, Udimet 520 (all are trademarks), and JIS NCF80A. be able to.

  In the method for producing a consumable electrode for remelting according to the present invention, soaking at a temperature lower than the temperature for solid solution is performed for 10 hours or more (preferably 700-950 ° C. for soaking is 10 hours or more, more preferably 850-950 ° C. (So uniform heat treatment for 10 to 100 hours), even if a large consumable electrode is manufactured, the hardness decreases due to an overaging phenomenon, that is, an increase in a brittle phase can be suppressed. As a result, it is possible to obtain a large-sized reconstituted consumable electrode that does not have a missing portion.

In the method for manufacturing the remelting consumable electrode according to the present invention, the recooling step is not required, so that the work efficiency is improved by that amount, and there is a risk of problems such as cracks due to the stress difference during recooling. There will be no.
On the other hand, the consumable electrode for remelting of the present invention is a consumable electrode for remelting made of a precipitation hardening type high nickel alloy manufactured by the method for manufacturing a consumable electrode for remelting, wherein the hardness is HRC35 or less. It is characterized by that.

  In this remelting consumable electrode, the embrittlement phase is suppressed to a small level and the hardness is HRC35 or less. Therefore, even if the diameter is 300 mm or more and the weight is 2000 kg or more, Therefore, there is almost no concern that the loss will occur, and the remelting efficiency and the yield will be improved.

In the method for manufacturing a remelting consumable electrode according to the present invention, the above-described configuration is adopted, so that improvement in manufacturing work efficiency and prevention of defects during manufacturing are prevented, and remelting does not occur. A very excellent effect is obtained that it is possible to manufacture a large-sized reconstituted consumable electrode capable of improving efficiency and yield.
Further, since the remelting consumable electrode of the present invention has the above-described configuration, even if it is a large consumable electrode, it is possible to avoid the occurrence of a chipping and to improve the remelting efficiency and the yield. This is a very good effect that is possible.

Hereinafter, the present invention will be described based on an embodiment.
In this embodiment, C: 0.05%, Ni: 51%, Cr: 15%, Mo: 1%, Nb: 1.3%, Al: 1.4%, Ti: 2.5% in mass%. , The alloy A containing 2% and the balance Fe is melted in a vacuum induction furnace, and the remelting consumable electrode 1 shown in FIG. 1 is manufactured by casting. As shown in Table 1, the hardness index was measured when each soaking at 650, 700, 750, 800, 850, 900, and 950 ° C. was performed for 0.5 to 130 hours (hr).

  As shown in Table 1 and FIG. 2, in the region where each soaking at 800 and 850 ° C. was performed for 5 hours or more, it was found that the hardness index was 30 units due to the overaging phenomenon, and soaking at 850 ° C. It can be seen that the hardness index is 20 in the region subjected to 100 hours, that is, the hardness is reduced.

Further, in the region subjected to soaking at 900 and 950 ° C. for 5 hours or more, particularly in the region subjected to 15 hours or more (region in the ellipse in the drawing), the hardness index is 20 units due to the overaging phenomenon. It can be seen that there is a decrease.
In addition, in the remelting consumable electrode 1 made of the alloy A of this embodiment, when soaking at 750 ° C., the hardness decreases in the region where the processing time exceeds 110 hours. Depending on the alloy having other composition, the hardness may decrease in a region where the processing time greatly exceeds 100 hours.

Thus, the remelting consumable electrode 1 made of the alloy A having the composition of the above embodiment was subjected to soaking at 900 ° C. in three patterns of 15 hours, 30 hours and 50 hours, and examples obtained thereby. Each of the 1 to 3 reconstituted consumable electrodes 1 was subjected to VAR and examined for the presence or absence of defects. The results shown in Table 2 were obtained.
At this time, a remelting consumable electrode 1 of Comparative Example 1 was obtained by subjecting the remelting consumable electrode 1 made of the alloy A to a soaking treatment at 900 ° C. for 5 hours, and the alloy A A remelting consumable electrode 1 of Comparative Example 2 was obtained by subjecting the remelting consumable electrode 1 to a remelting consumable electrode 1 of Comparative Example 2 obtained by subjecting the remelting consumable electrode 1 to 650 ° C. for 15 hours. 1 is a remelting consumable electrode 1 of Comparative Example 3 that is not subjected to soaking at all, and these redissolving consumable electrodes 1 of Comparative Examples 1 to 3 are each missing when subjected to VAR. The presence or absence was examined, and the results are also shown in Table 2.

  As shown in Table 2, each of the remelting consumable electrodes 1 of Examples 1 to 3 subjected to a soaking treatment at 900 ° C. for 15 to 50 hours did not have any defects, whereas In each of the remelting consumable electrodes 1 of Comparative Examples 1 to 3 in which the heat treatment time is short, the soaking temperature is low, or the soaking heat treatment is not performed, there are defects.

  Also, in response to this result, the large-sized remelting consumable electrode 1 is manufactured in accordance with the specifications of the above-mentioned Example 1, and the redissolving consumable electrode 1 of Example 1 obtained in this way is likely to be missing during VAR operation. When compared with a conventional consumable electrode for remelting that does not occur, the results shown in Table 3 were obtained.

  As shown in Table 3, when the diameter and single weight of the conventional remelting consumable electrode are both expressed by a unit coefficient (1), the diameter and single weight of the large remelting consumable electrode 1 in Example 1 are respectively Thus, it was demonstrated that the manufacturing methods of Examples 1 to 3 can provide a large remelting consumable electrode that does not lack.

It is a perspective explanatory view of the remelting consumable electrode manufactured by the manufacturing method of the remelting consumable electrode according to the present invention. It is a graph explaining the reason for limiting numerical values of the temperature and time of soaking in the method for producing a consumable electrode for remelting according to the present invention.

Explanation of symbols

1 Consumable electrode for remelting

Claims (4)

When producing a consumable electrode for remelting comprising a precipitation hardening type high nickel alloy having a nickel content exceeding 30% by mass and a total content of aluminum, titanium, niobium and tantalum exceeding 2.0% by mass,
A method for producing a remelting consumable electrode, comprising subjecting a precipitation hardening type high nickel alloy formed into a shape of a remelting consumable electrode to a soaking treatment at a temperature lower than a temperature at which the solution is solidified for 10 hours or more.   The method for producing a consumable electrode for remelting according to claim 1, wherein a soaking process at 700 to 950 ° C is performed for 10 hours or more.   The manufacturing method of the consumable electrode for remelting of Claim 2 which performs soaking | uniform-heating treatment of 850-950 degreeC for 10 to 100 hours. A remelting consumable electrode comprising a precipitation hardening type high nickel alloy produced by the method for producing a remelting consumable electrode according to any one of claims 1 to 3,
A consumable electrode for remelting, characterized in that the electrode hardness is HRC35 or less.

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