JPS61276919A - Production of free-cutting fe-ni-co sealing alloy - Google Patents

Abstract

PURPOSE:To produce the titled sealing alloy having excellent machineability by incorporating a specific ratio each of Pb, Bi and Te into an Fe-Ni-Co sealing alloy and subjecting the alloy to a specific ratio of cold working in the stage of blooming then to hot working. CONSTITUTION:1 or >=2 kinds among Pb, Bi and Te are incorporated at 0.02-0.5wt% in total into the Fe-Ni-Co sealing alloy consisting essentially of Fe and contg. Ni and Co. The cast ingot of such alloy is subjected to at least >=10%, more preferably about 10-20% cold working in the stage of blooming said ingot by forging or rolling and thereafter the ingot is subjected to hot working. The sealing alloy contains usually about 27-31% Ni and about 14-18% Co. The blooming is thus made possible without generating a crack, etc. in the cast ingot of the alloy and the excellent machine ability is obtd. while the good characteristics as the sealing alloy are maintained.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to the production of so-called sealing alloys, and more specifically, to the blooming process of an ingot of a free-cutting Fe-Ni-Co-based sealing alloy. Regarding technology.

(Prior art and problems) Fe-Ni-Co alloys are suitable for glass sealing because they have similar expansion curve characteristics to hard or soft glasses, and in particular, 29%Nj-18%Co- The 53% Fe alloy is called Kovar, and is often used as a sealing alloy for hard glass. Such sealing alloys are required to have excellent workability because they are used after being formed into various shapes.

However, when cutting this Fe-Ni-Go alloy, it is extremely sticky, which causes burrs to form on the surface, resulting in a poor machined surface, shortening the life of the cutting tool, and even producing chips. There were drawbacks such as easy continuity.

Therefore, like free-cutting steel, the free-cutting elements pb, Bi, and T
Attempts have been made to improve free machining by adding elements such as e, but these free machining elements significantly impede hot workability and cause cracks, making even blooming impossible. It was hoped that a solution would emerge.

(Object of the Invention) The present invention has been made in view of the above circumstances, and is a method for casting a free-cutting Fe-Ni-Co sealing alloy to which free-cutting elements such as Pb, Bj, and Te are added. The object of the present invention is to provide a method for blooming a lump without causing cracks or the like.

(Structure of the Invention) In order to achieve the above object, the present inventors first performed hot working such as blooming rolling on an ingot of the above-mentioned conventional free-cutting Fe-Ni-Co sealing alloy. We also investigated the causes of cracks that occur during this process. As a result, in the ingot of the alloy to which free-cutting elements such as Pb, Bj, and Te are added, the free-cutting elements form a brittle film or exist in the form of a plate at the grain boundaries, and this film or plate-like structure It was found that this caused cracking during hot working. Therefore, as a countermeasure, based on the knowledge that cracking can be prevented by dividing the film or plate-like body of the free-cutting element by some means before hot working,
As a means of achieving this, we came up with the idea of applying at least 10% cold working to the ingot in advance. The present invention was developed as a result of detailed research on the amount of free-cutting elements to be taken into account when implementing this new method.

That is, the gist of the present invention is Fe-Ni-C which has Fe as a main component and contains Ni and CO.

An ingot of a sealing alloy containing a total of 0.02 to 0.5% by weight of one or more of PB, old, and Te is decomposed by forging or rolling. In this process, the ingot is first cold-worked by at least 10% and then hot-worked.

The present invention will be explained in detail below based on examples.

The Fe-Ni-Co-based sealing alloy to which the method of the present invention is applied contains free-cutting elements as described below, but it is mainly composed of FC, contains appropriate amounts of Nj and CO, and can be applied as a sealing alloy. It has a component composition, usually Nj: 27 to 31%,
Co: ], 4 to 18%.

It is necessary to apply cold working of at least 10% to the Fe-Ni-Co alloy ingot before hot working. If the cold working is less than 10%, the formed film or plate-like body of the free-cutting element cannot be completely divided, and cracks will occur during subsequent working. Although the means and mode of cold working are not particularly limited, a cold working ratio of about 10 to 20% is practical in actual operation.

As the cold working described above improves workability,
In the subsequent processing, normal blooming processing can be performed, and hot processing by forging, rolling, etc. can be performed.

Note that the cold working rate usually refers to the cross-sectional reduction rate, but it also includes cases where even if the cross-section is constant when cold working is applied, the cross-section is deformed and a deformation rate occurs.

The free cutting elements added to the above alloy are Pb, Bi and Te.
The total amount of one or more species is contained in the range of 0.02 to 0.5%. If it is less than 0.02%, it will not contribute to free machinability, and if it is added in a large amount exceeding 0.5%, cracks will occur.
It becomes impossible to use it as a sealing alloy.

(Example) An ingot of Fe-Ni-Co alloy having the composition shown in Table 1 was subjected to cold working at various processing rates of 5 to 25%, and then hot forged. did. After processing, 600℃
A Charpy impact test without a notch was conducted to examine hot forgeability (presence or absence of cracking), and a drill cutting resistance test was also conducted to examine machinability. The trill cutting resistance test was conducted using a 3mmφ straight shank drill (SK
H9), feed 0, 1 n+m/rev, 1
0n+l]l Blind hole depth, cutting speed 25m/min
This was done without using cutting oil. The above results are shown in the same table.

[Left below] As can be seen from Table 1, in the comparative method, if the total amount of free-cutting elements added is less than 0.02%, no cracking occurs during hot working even without cold working in advance. , the machinability is poor (Nn 11 ), and on the other hand, when a large amount of free-cutting elements exceeding 0.5% is added (Nni2), cracks occur. However, even if free-cutting elements are added in the range of 0.02 to 0.5%, cracks will occur if the cold working rate is less than 10% (
Nn13).

On the other hand, in the method of the present invention (Nα1 to 10), even if hot working is performed after cold working in advance, no cracks occur and the machinability is excellent. Note that all of the target alloys for the method of the present invention had good properties as sealing alloys.

(Effects of the Invention) As described in detail below, according to the present invention, free-cutting Fe-
It is possible to bloom Ni-Co alloy ingots without causing cracks, and it also provides excellent machinability while maintaining good properties as a sealing alloy.
The effect is very thick ().

Claims (1)

[Claims] Fe-Ni-C containing Fe as the main component and Ni and Co
o-based sealing alloy, one of Pb, Bi and Te
When blooming an ingot of the alloy containing a total amount of 0.02 to 0.5% by weight of one or more species by forging or rolling, first cold-working the ingot by at least 10% or more, Free machinability F characterized by hot working after
A method for manufacturing an e-Ni-Co based sealing alloy.