JPH0778271B2 - Method for producing Fe-Ni based alloy excellent in streak unevenness suppressing effect during etching - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention provides Fe, which has an excellent effect of suppressing streak unevenness during etching.
The present invention relates to a method for producing a Ni-based alloy, and more particularly to a Fe-Ni-based alloy that is preferably used as a material for electronic devices such as shadow masks for color television Braun tubes and fluorescent display tubes.

Incidentally, the Fe-Ni-based alloy of the present invention, 36Ni amber alloy for shadow mask, 42Ni alloy for lead frame, electronic used for the low thermal expansion characteristics and magnetic characteristics, Fe-Ni-based alloy for electromagnetic, Also, it is intended for continuous cast materials of Fe-Ni alloys such as permalloy alloys used as electromagnetic materials.

[Conventional technology]

Iron-nickel alloy steel (Fe-Ni alloy) for shadow mask materials of color TV cathode-ray tubes produces white streaky patterns "streaks" when a shadow mask is manufactured by photo-etching perforation of this steel. It was pointed out that there were drawbacks.

Heretofore, several techniques have been proposed for suppressing the occurrence of streak unevenness during etching.
According to the technology disclosed in Japanese Unexamined Patent Publication No. -128253, after heating an ordinary ingot at 850 ° C. or higher, forging is performed at a total cross-sectional reduction rate of 40% or more in each heat, thereby reducing the nickel segregation portion. The occurrence of the streak unevenness is suppressed.

Further, the technology disclosed in Japanese Patent Laid-Open No. 61-223188 controls the segregation rate and segregation zone of nickel by preventing segregation during ingot production or by performing nickel diffusion treatment by heat treatment during the strip manufacturing process. Thus, uneven etching streaks are suppressed.

[Problems to be Solved by the Invention]

However, the above-mentioned conventional technique disclosed in JP-A-60-128253 is characterized in that forging is performed so that the total cross-section reduction rate exceeds 40%, but generally this degree of work is normally performed. This is a load, and segregation of various elements is not easily eliminated by such a method, and thus it was insufficient to prevent the occurrence of streak unevenness during etching.

On the other hand, the above-mentioned conventional technique disclosed in Japanese Patent Laid-Open No. 61-223188 is characterized by reducing the segregation of its components through the diffusion of Ni by high temperature heat treatment, but the plate thickness is thinner than the heating at the slab stage. Therefore, there is a problem in that the oxidation loss is relatively large and the yield is significantly reduced.

Further, these conventional techniques have a problem that the yield is low and the cost is high, although the material is an ordinary ingot, and therefore there is no particular problem with the solidification structure.

As described above, none of the conventional techniques can completely overcome the streak unevenness at the time of etching, and it has not been possible to industrially manufacture an inexpensive product.

An object of the present invention is, in view of the circumstances of the art, an alloy material that does not cause streaking during etching, that is,
Fe containing Ni of 30 to 80% and B of 0.001 to 0.03%
-We are proposing a method of manufacturing Ni-based alloys using continuous casting materials.

[Means for Solving the Problems]

Therefore, the present inventors have made Fe-
Various studies were conducted on the streak unevenness of Ni-based alloys. As a result, they found that the main causes of the uneven streaks that were found were component segregation of impurity elements such as C, Si, Mn, and Cr, and differences in crystal structure.

For example, in the component segregated portion of the impurity element such as C, Si, Mn, and Cr, the etching speed changes as compared with the other portions, so that the difference in the hole shape is caused during the photoetching perforation, which causes streak unevenness. It will be.

On the other hand, regarding the difference in crystal structure, for example, (100)
A portion where a large number of planes are oriented has a higher etching rate than other portions, resulting in a difference in hole shape during photoetching perforation. This is the solidification structure during casting,
That is, it is caused by the existence of a columnar structure having a specific orientation, and this columnar structure is elongated in the rolling direction while changing the shape without disappearing in the subsequent processing and heat treatment steps, and finally causes the streak unevenness. It will be.

In addition, according to the smelt found by the present inventors, it was found that the use of B as an additive component in the Fe-Ni alloy has an effect of severing the columnar crystals during slab heating and accelerating randomization. did.

From this, in the present invention, an attempt was made to overcome the above-mentioned problems, aiming at not only the suppression of component segregation but also the adjustment of the crystal structure by the synergistic effect of the addition of B.

That is, as a means for overcoming the problem, the present invention firstly proposes, as a case of a slab having an equiaxed crystal ratio of 20% or less,
Of 30% to 80% by weight, 0.001 to 0.03% by weight of B, and the balance being mainly Fe, the continuously cast slab of the Fe-Ni alloy at 1000 ° C.
Secondly, heating and holding at the above temperature for 1 hour or more, and secondly, in the case of a slab having an equiaxed crystal ratio exceeding 20%, this continuous casting slab is heated and held at a temperature of 950 ° C or higher for 1 hour or more. Therefore, we propose a method for producing Fe-Ni alloys, which has an excellent effect of controlling streak unevenness during etching.

[Action]

In the present invention, the lower limit of the Ni content of the material is set to 30 wt% (hereinafter simply abbreviated as “%”)
When using a Fe-Ni alloy as the above functional material,
This is because if the content is less than 30%, sufficient electromagnetic characteristics are not exhibited and it cannot withstand practical use. Conversely, if Ni exceeds 80%,
This is because the quality of electronic and electromagnetic materials deteriorates.

As a material to be perforated by photoetching, it is more preferable to use an Fe-Ni-based alloy containing 50% or less of Ni.

In addition, B is an important element that brings out the characteristics of the Fe-Ni alloy of the present invention, and prevents segregation of impurity elements such as C, Si, Mn, and Cr to the crystal grain boundaries, and at the same time grain boundaries themselves. And preferentially agglomerate in other defect portions to become nuclei for recrystallization, and refine the crystal grains to improve equiaxed crystallization. However, such an effect is insufficient at a content of less than 0.001%, and a remarkable effect is exhibited as the content increases, but 0.03%
When added in excess of%, various boride compounds containing C, O, N are produced in addition to M ₂ B (Ni, Cr, Fe) intermetallic compounds, increasing the risk of solidification cracking at high temperatures. So the upper limit is 0.03%
Need to be limited to.

The Fe-Ni alloy material used in the present invention is not an ordinary ingot material but a continuous casting material. The reason why the material to be treated is a continuous cast material (slab) is that the continuous cast slab has less macroscopic component segregation and is excellent in processing and heat treatment characteristics as compared with the ordinary ingot material. .

In addition, in the case of this continuous cast slab, the crystal structure of the cross section of the cast slab has a small amount of segregation in which columnar crystals have developed from both sides, but on the other hand, when attention is paid to "streak unevenness", the following phenomenon is also observed. It was

That is, the streak unevenness is not only the segregation of the components but also the columnar crystals at the time of casting not disappearing by the subsequent processing and heat treatment.
It was found that this was caused by what was stretched in the rolling direction by rolling while changing the shape. Moreover, according to the research conducted by the present inventors, when the columnar crystals having a specific orientation when processed to the final plate thickness have a short length, the width and the length thereof are relatively small, and when the holes are formed by etching, No difference in the partial etching rate that occurred was observed and, therefore, was not observed as continuous stripe unevenness. However, in the columnar crystals (crystal grains) having a long length, the ones corresponding to the width and length of the columnar crystals remained as they were even after the processing, that is, remained large, which resulted in stripe unevenness during etching. .

The length of the columnar crystal, which is the limit of whether streaks appear or not, is 20% in the equiaxed crystal ratio of the slab in the case of the above component composition, that is, when B is included.

As a method of overcoming both of these problems, the present invention provides a suitable heat treatment method with an equiaxed crystal ratio of 20% as a boundary so that streak unevenness does not occur in any case.

Next, the reason for setting the slab heat treatment temperature to 1000 ° C or higher is that in a slab with an equiaxed crystal ratio of 20% or less, the effect of columnar crystals with stable orientation is strong, so at a low temperature of 1000 ° C or less,
This is because it is not sufficient to divide and randomize the columnar crystals in order to prevent stripe unevenness.

On the other hand, when the equiaxed crystal ratio exceeds 20%, the columnar crystals do not remain even after hot rolling. Therefore, the occurrence of streak unevenness is small, so a heat treatment temperature as low as 950 ° C may be used. is there. However, this heat treatment temperature is 950 ℃
In the following cases, segregation is not sufficiently reduced, and streak unevenness due to segregation occurs.

In the present invention, in order to control the equiaxed crystal ratio of the continuously cast slab as described above, an electromagnetic stirrer (EMS) is installed in the mold or the secondary cooling zone of the continuous casting machine, and electromagnetic force is applied. By adjusting, the unsolidified molten metal in the slab is stirred to bring the equiaxed crystal ratio to a target. Alternatively, the equiaxed crystal ratio can be targeted by controlling the pouring temperature and ultrasonic vibration.

As described above, the present invention, by adding an appropriate amount of B to the Fe-Ni-based alloy, controlling the solidification during continuous casting, and subjecting the continuous casting slab to an appropriate heat treatment,
Homogenization of crystals and reduction of component segregation can be realized at the same time. Therefore, in the present invention, it is possible to produce a Fe-Ni-based alloy that does not cause stripe unevenness during etching.

〔Example〕

Table 1 shows the conditions of implementation and the results such as the chemical composition and equiaxed crystal ratio of the Fe-Ni alloy used in this example.

The alloys shown in Table 1 and specifically targeted by the present invention are obtained by melting molten metal in an electric furnace, followed by AOD method or VOD.
After refining by the method, then a continuous casting slab as shown in Table 1 was obtained by operating a magnetic stirrer attached to the continuous casting machine while controlling the equiaxed crystal ratio.

Then, this continuous cast slab is cooled and cared for, and then 95
The coil was heated and held at a predetermined temperature of 0 ° C. or higher for 1 hour or longer, and then hot-rolled to obtain a coil having a thickness of 5.5 mm. After the hot rolling, the final product was obtained by performing a treatment according to a conventional method in which cold rolling and heat treatment were appropriately combined according to a conventional method.

The test material produced in this manner was subjected to actual photoetching opening with a ferric chloride solution (specific gravity: 1.45, 50 ° C.) to investigate whether streaks occurred.

The results are shown in Table 1.

As can be seen from Table 1, the Fe-Ni-based alloy produced according to the method of the present invention is compared with the Fe-Ni-based alloy (comparative example) having the same composition and produced by the conventional method. Then, almost no streaking was observed during etching, and it was revealed that the alloy was an excellent material for etching.

[Effects of the Invention] As described above, the Fe-Ni-based alloy produced by the method of the present invention and containing an appropriate amount of B has no streaking after photoetching and therefore has desirable properties as an electronic or electromagnetic material. Fe-Ni alloy can be provided at low cost.

Claims (2)

[Claims] 1. An equiaxed crystal ratio of an Fe-Ni alloy containing 30 to 80 wt% of Ni, 0.001 to 0.03 wt% of B, and the balance being mainly Fe 20
% Or less of a continuously cast slab is heated and held at a temperature of 1000 ° C. or more for 1 hour or more, and a method for producing a Fe—Ni alloy having an excellent effect of suppressing streak unevenness during etching. 2. An Fe-Ni alloy containing 30 to 80 wt% of Ni and 0.001 to 0.03 wt% of B, the balance being mainly Fe, is continuously cast, and at the time of casting, electromagnetic stirring, control of pouring temperature, or During etching, which is characterized by preparing a continuous casting slab whose equiaxed crystal ratio of the slab exceeds 20% by applying ultrasonic vibration, and heating and maintaining this continuous casting slab at a temperature of 950 ° C or higher for 1 hour or more. A method for producing a Fe-Ni based alloy excellent in the streak unevenness suppressing effect.