JPH11286751A - Free cutting low thermal expansion cast alloy and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To produce a free cutting low thermal expansion cast alloy which does not require much cost for machining, and to provide a method for producing it. SOLUTION: The free cutting low thermal expansion cast alloy having a compsn. contg., by weight, 0.5 to 1.5% C, <=1% Si, 25 to 43.5% Ni and <=20% Co, furthermore contg. one or two kinds of S and Se in the range of 0.04%<=S+0.4Se<=0.12%, contg. Mn in the range of 1>=Mn>=2.3(S+0.4Se)+0.2, also satisfying 34.5%<=Ni+0.8Co<=43.5%, and the balance substantial Fe is obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a free-cutting low-thermal-expansion cast alloy suitable for use in precision machine parts and the like, and a method for producing the same. The free-cutting low-thermal-expansion cast alloy of the present invention is:
Suitable for (1) semiconductor-related equipment, (2) measuring equipment, (3) machine tools, (4) optical equipment, (5) molds, etc.
As (1), for example, a platen or arm such as a polishing machine or a stepper, a roll frame of a slicing machine, a rotor of a dry vacuum pump, a recognition unit arm of a mounting device, a rack of a bonding machine, a block or frame of a drawing device, silicon Bases and columns of wafer grinders, trays of inspection devices, bases and frames of other exposure devices, and the like, and (2) include, for example, a gauge of a squareness measuring device, a C frame of a non-contact plate thickness measuring device, A spindle of a thin film thickness measuring device, a measuring beam of a bridge measuring device, a frame of an ultra-precision aspherical measuring device, a bobbin of an optical gyro, a mirror stand or a light source stand of a component analyzer, and the like are examples of (3). Precision grinding machine base / column, centerless grinding machine spindle and inspection machine, cutting machine turret, machining center spindle Dollar head, magnet chuck of cylindrical grinder, table of aspherical processing machine, motor case of printed circuit board drilling machine, lower arm of wire electric discharge machine, connecting rod of precision press machine, column of jig borer, etc. For example, there are a lens barrel of a surveying telescope, a base of a laser oscillator, a base or a frame of a laser processing machine, a lens support of an astronomical telescope, a housing of a recognition device, and the like. And a GFRP molding die, a press molding positioning jig, and a plastic injection molding hot runner.

[0002]

2. Description of the Related Art Invar (36% Ni-Fe alloy) and Super Invar (32% Ni-5% Co-Fe alloy) have been known as practical low thermal expansion alloys. Alloy from room temperature to 100
Since the coefficient of thermal expansion between ° C and 0 ° C to 1 × 10 ⁻⁶ / ° C is extremely low, it is used for applications requiring dimensional accuracy such as precision machine parts. In addition, 42 in consideration of use at higher temperatures
% Ni-Fe alloy or Kovar (29% Ni-17Co-
Fe alloy), for example, in Kovar from room temperature to 450
It has a characteristic that the coefficient of thermal expansion between ° C and that of Invar and Super Invar is smaller than that of Invar and Super Invar, and is used for applications that require low thermal deformation at high temperatures. For these precision machine parts and the like, a casting alloy formed by casting in a mold close to the product shape is used, and a semi-finished product manufactured by the casting alloy is cut into a final shape.

However, these low thermal expansion alloys
Since the machinability is low and the cutting work usually performed to finish the material into a desired shape requires a great deal of cost, the range of use thereof is limited.

On the other hand, as disclosed in Japanese Patent Application Laid-Open No. 3-90541, a material in which graphite is distributed in the structure has a low thermal expansion property comparable to that of Invar or Super Invar and has a large machinability. Has been improved. However, recently, further improvement in machinability has been demanded in order to realize short delivery time and low cost.

[0005]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and provides a free-cutting, low-thermal-expansion cast alloy which does not require a large cost for cutting and a method for producing the same. The purpose is to:

[0006]

The inventor of the present invention has conducted intensive studies to solve the above-mentioned problems, and as a result, has found that the above-mentioned Japanese Patent Laid-Open Publication No.
Based on the alloy composition disclosed in Japanese Patent No. 541, by adding S and / or Se, Mn, and Ca in a certain range, it is possible to obtain a cast alloy having high machinability while satisfying low thermal expansion properties. Was found. Further, it has been found that the thermal expansion coefficient is further reduced by water cooling such an alloy from 700 to 900 ° C.

[0007] The present invention has been made based on such findings, and in terms of% by weight, C: 0.5 to 1.5%;
Si: 1% or less, Ni: 25 to 43.5%, Co: 20
% Of S and Se.
0.04% ≦ S + 0.4Se ≦ 0.12
%, And Mn is 1 ≧ Mn ≧ 2.3 (S + 0.
4Se) +0.2 and 34.5% ≦
An object of the present invention is to provide a free-cutting, low-thermal-expansion casting alloy that satisfies Ni + 0.8Co ≦ 43.5% and is substantially composed of Fe.

[0008] The present invention also relates to a C: 0.5% by weight.
1.5%, Si: 1% or less, Mn: 1% or less, Ni:
25 to 43.5%, Co: contained in a range of 20% or less,
Further, one or two of S and Se are set to 0.04
% ≦ S + 0.4Se ≦ 0.12%
Is added within the range of Ca ≧ 3.8 (S + 0.4Se) and satisfies 34.5% ≦ Ni + 0.8Co ≦ 43.5%, with the balance substantially consisting of Fe. The present invention provides a castable low thermal expansion alloy.

Further, the present invention provides a method for producing a free-cutting, low-thermal-expansion cast alloy, characterized by rapidly cooling a material having any one of the above-mentioned compositions from a temperature of 700 ° C. to 900 ° C. Things.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described specifically. The basic composition of the alloy according to the invention is, in% by weight, C:
0.2% or less, Si: 1% or less, Ni: 25 to 43.5
%, Co: 20% or less, 34.5% ≦ Ni + 0.8Co
≦ 43.5%, and one or two of S and Se are 0.04% ≦ S + 0.4Se ≦ 0.12%, M
n is 1 ≧ Mn ≧ 2.3 (S + 0.4Se) +0.2, or C: 0.2% or less, Si: 1% or less, M
n: 1% or less, Ni: 25 to 43.5%, Co: 20%
Hereinafter, 34.5% ≦ Ni + 0.8Co ≦ 43.5%, and one or two of S and Se are 0.04
% ≦ S + 0.4Se ≦ 0.12%, Ca ≧ 3.8 (S +
0.4Se), and the balance is substantially Fe.

C: 0.5-1.5% When C forms a solid solution in an austenite matrix, it causes a remarkable increase in the coefficient of thermal expansion.
Machinability and castability can be improved as compared with cast steel containing no graphite. However, when the amount of C is less than 0.5%, the amount of graphite is small, and the effect of improving the machinability is not seen, and the castability decreases due to an increase in the melting temperature. On the other hand, if it exceeds 1.5%, the desired low thermal expansion property cannot be obtained. Therefore,
The C content is in the range of 0.5 to 1.5%.

Si: 1% or less Si is an element added as a deoxidizing agent, but if it exceeds 1%, the effect of an increase in the coefficient of thermal expansion is large. Therefore,
The amount of Si is set to 1% or less. However, from the viewpoint of improving castability, the content is preferably 0.5% or more.

Mn: 1% or less Mn is an element effective for deoxidation and for fixing S to improve workability. However, if it exceeds 1%, the coefficient of thermal expansion increases. Therefore, the Mn content is set to 1% or less.

Ni: 25 to 43.5% Ni is an element necessary for reducing thermal expansion together with the following Co. If the amount of Ni is less than 25%, the desired low thermal expansion property cannot be obtained even if the amount of Co is adjusted, and if it exceeds 43.5%, the low thermal expansion property cannot be obtained.
The range is 5%.

Co: 20% or less Co is an element added for realizing a decrease in the coefficient of thermal expansion in combination with the above-mentioned Ni, but if it exceeds 20%, the coefficient of thermal expansion becomes high. And

34.5% ≦ Ni + 0.8Co ≦ 43.5% Ni + 0.8Co is Ni equivalent, and even if Ni and Co satisfy the above range, Ni equivalent is less than 34.5% and 43.5%. If it is higher, a low coefficient of thermal expansion cannot be obtained. Therefore, the Ni equivalent is in the range of 34.5 to 43.5%.

The preferred ranges of Ni, Co and Ni equivalent vary depending on the temperature range in which low thermal expansion is required. That is, in order to set the coefficient of thermal expansion in the range of 20 to 150 ° C. to 4 × 10 ⁻⁶ / ° C. or less, Ni: 27 to 3
7.5%, Co: 11% or less, Ni equivalent: 34.5-3
7.5% is preferred. Further, in order to set the coefficient of thermal expansion in the range of 20 to 300 ° C. to 6 × 10 ⁻⁶ / ° C. or less, N
i: 26 to 40.5%, Co: 17% or less, Ni equivalent:
37.5-40.5% is preferred. Furthermore, 20 to 45
In order to make the thermal expansion coefficient in the range of 0 ° C. 8 × 10 ⁻⁶ / ° C. or less, Ni: 25 to 43.5%, Co: 20% or less, Ni equivalent: 40.5 to 43.5% Is preferred.

In the present invention, in addition to the above, one or two of S and Se are further added in an amount of 0.04% ≦ S + 0.4.
Se ≦ 0.12%, Mn is 1 ≧ Mn ≧
2.3 (S + 0.4Se) +0.2, or one or two of S and Se in a range of 0.2.
Contained in the range of 04% ≦ S + 0.4Se ≦ 0.12%,
And Ca is added in a range of Ca ≧ 3.8 (S + 0.4Se).

S and Se are elements that form sulfide and selenide, reduce cutting resistance, extend tool life and contribute to improvement in machinability. With high machinability. If the value of S + 0.4Se is less than 0.04%, the effect of improving machinability is not obtained, and if it exceeds 0.12%, the ductility is not recovered even by using Mn or Ca described later. Therefore, the value of S + 0.4Se is set to 0.04
０．１0.12%.

Mn or Ca has an effect of improving the form of sulfide and selenide by binding to S and Se, suppressing the decrease in ductility, and can contain S and Se necessary for improving machinability. In order to exhibit the effect, it is necessary to define the relationship with S + 0.4Se, and Mn is 2.3 (S + 0.4Se) +0.2 or more.
Ca needs to be 3.8 (S + 0.4Se) or more.

The alloy of the present invention is intended for a cast alloy produced by casting in a mold, but the production conditions are not particularly limited.

However, in the present invention, it is preferable to rapidly cool a raw material manufactured in a predetermined shape from a temperature in the range of 700 to 900 ° C. Thereby, micro segregation of Ni or Co is alleviated, and the thermal expansion coefficient can be further reduced. The rapid cooling method is preferably water cooling, but may be air cooling or oil cooling.

[0023]

Embodiments of the present invention will be described below. With a high frequency induction melting furnace, alloys having the chemical compositions shown in Tables 1 and 2 were melted and cast, and a φ35 mm × L220 mm round bar,
And a round bar of φ100 mm × L400 mm was obtained. In Table 1, No. Nos. 1 to 28 are materials of the present invention. 1 to
No. 9 for low temperature, No. 9 Nos. 10 to 18 are for medium temperature. 19 ~
28 is for high temperature. Also, in Table 2, 29-35
No. is a comparative material for low temperature alloys. Nos. 38 to 44 are comparative materials for middle temperature alloys. 47-53 are comparative materials for high temperature alloys, N
o. Reference numerals 56 to 59 are comparative materials in which any of Ni, Co, and Ni equivalent is deviated. Further, in Table 2, No. Nos. 36 and 37 are conventional materials for low temperature alloys. Nos. 45 and 46 are conventional materials of middle temperature alloys. Reference numerals 54 and 55 are conventional materials of a high temperature alloy.

[0024]

[Table 1]

[0025]

[Table 2]

The thermal expansion coefficient was measured using the above-mentioned round bar of φ35 mm × L220 mm. The coefficient of thermal expansion is 20 to 150 ° C for low temperature alloys, 20 to 300 ° C for medium temperature alloys,
For high temperature alloys, measurements were made in the range of 20-450 ° C. The machinability was evaluated using φ100 mm × L400 mm. The machinability is no. 36, N for medium temperature
o. No. 45 for high temperature use. The tool life ratio of each of the sample Nos. 54 was evaluated as 1 and the cutting force was evaluated. Tables 3 and 4 show these results. In addition, in these machinability tests, a carbide tool was used as a cutting tool, and the cutting speed was 100 m.
/ Min, cut 2.0 mm, feed 0.2 mm / rev.
Under the conditions described above.

[0027]

[Table 3]

[0028]

[Table 4]

As shown in Table 3, it was confirmed that in the examples of the present invention, it was possible to maintain the desired low thermal expansion property and obtain better machinability than the conventional material.

On the other hand, as shown in Table 4, Ni,
No. of the comparative example in which the Co amount or the Ni equivalent is out of the range of the present invention. Nos. 56 to 59 had a large thermal expansion coefficient at any temperature and were unsuitable as a low thermal expansion material. In addition, in the case of No. Nos. 29, 38 and 47 had poor machinability.
No. 3 having a large amount of C, Si and Mn. 30-32, 39-4
1,48 to 50 showed large values of the coefficient of thermal expansion. In addition, S.sub. 33, 42, 51
Is poor in machinability, and there are many S + 0.4Se,
No. 4 containing less Mn than 0.4Se. 34, 35, 4
3,44,52,53 had low elongation.

Next, the above No. 1,2,10,11,1
The thermal expansion coefficients of as-cast and water-cooled from 850 ° C. were measured using φ35 mm × L220 mm round bar samples having compositions of 9, 20. No. for low temperature 1, 2 is 2
No. 0 to 150 ° C., medium temperature 10 and 11 are 20 to 30
No. 0 ° C and high temperature 19 and 20 were measured at 20 to 450 ° C. Table 5 shows the results.

[0032]

[Table 5]

As shown in Table 5, by water cooling,
It was confirmed that the coefficient of thermal expansion was further reduced as compared to as-cast.

[0034]

As described above, according to the present invention,
A low thermal expansion cast alloy having free-cutting properties can be obtained.
Therefore, a great deal of cost is not required for cutting.

Claims (3)

[Claims] C. 0.5 to 1.5% of Si, 1% or less of Si, 25 to 43.5% of Ni, 20% or less of Co, and One or two of Se and 0.04
% ≦ S + 0.4Se ≦ 0.12%
In the range of 1 ≧ Mn ≧ 2.3 (S + 0.4Se) +0.2, and 34.5% ≦ Ni + 0.8Co ≦ 4
A free-cutting, low-thermal-expansion cast alloy that satisfies 3.5% and the balance substantially consists of Fe. 2. In% by weight, C: 0.5 to 1.5%, Si: 1% or less, Mn: 1% or less, Ni: 25 to 43.5%, Co: 20% or less. And one or two of S and Se at 0.04
% ≦ S + 0.4Se ≦ 0.12%
Is added within the range of Ca ≧ 3.8 (S + 0.4Se) and satisfies 34.5% ≦ Ni + 0.8Co ≦ 43.5%, with the balance substantially consisting of Fe. Low thermal expansion cast alloy. 3. A method for producing a free-cutting, low-thermal-expansion casting alloy, comprising rapidly cooling a material having the composition according to claim 1 from a temperature of 700 ° C. or more and 900 ° C. or less.