JP4737614B2 - Fe-Ni alloy plate and method for producing Fe-Ni alloy plate - Google Patents

Description

  The present invention relates to an Fe—Ni alloy plate having a high magnetic permeability and a method for producing an Fe—Ni alloy plate.

There is JIS PC permalloy as an alloy having a high magnetic permeability, which is applied as a magnetic head or a magnetic shield material.
With respect to this PC permalloy, various proposals have been made to further increase the magnetic permeability. For example, in JP-A-7-188817 (see Patent Document 1), in addition to the basic permalloy composition, 3.2 ≦ (2.02 × [Ni] -11.13 ×) in order to increase the initial permeability. [Mo] −1.25 × [Cu] −5.03 × [Mn]) / (2.13 × [Fe]) ≦ 3.8 is satisfied, the amount of impurities such as Sb is adjusted, Furthermore, the component which adds Ca in order to improve hot workability is disclosed.
Moreover, the manufacturing method of PC permalloy described in Unexamined-Japanese-Patent No. 2002-173745 (refer patent document 2) adjusts it to the cast structure | tissue where the area ratio of an equiaxed crystal is 1% or less by rapidly cooling molten steel at the time of casting. A method for improving magnetic properties by forming a slab by casting, soaking the cast slab, and then hot rolling is shown.
JP-A-7-188817 JP 2002-173745 A

In JP-A-7-188817 in which Ca is positively added, Ca is contained in a weight ratio Ca / S to S in the range of 1.5 to 6.0. However, there is a problem that inclusions that deteriorate magnetism increase due to positively added Ca.
In the method disclosed in JP-A-2002-173745, the area ratio of equiaxed crystals is set to 1% or less to improve the magnetic characteristics. However, in order to reduce the area ratio of equiaxed crystals to 1% or less, there is no special equipment that can quickly solidify molten steel or a specially shaped mold that can produce an ultra-flat steel ingot. It is extremely difficult to make the crystal area ratio 1% or less. In particular, in order to reduce inclusions, it becomes even more difficult when a large steel ingot having a weight of 5 tons or more is formed in a process such as vacuum melting-steel ingot.
An object of the present invention is to provide an Fe—Ni alloy plate having an optimum component capable of realizing a high magnetic permeability and a manufacturing method capable of obtaining a high magnetic permeability even with a large steel ingot.

Although it is a PC permalloy having a high magnetic permeability, it is very difficult to stably obtain, for example, an initial permeability of 300,000 or more and a maximum permeability of 400,000 or more. A desired high magnetic permeability cannot be obtained due to a slight difference in components. Therefore, the optimum chemical composition was studied earnestly.
Further, as a result of studying a manufacturing method that can stably obtain high magnetic permeability without using special manufacturing equipment or a specially shaped mold, the present invention has been achieved.
That is, the present invention, in mass%, C: 0.03% or less, Si: 0.05-2.0%, Mn: 1.3-2.0%, Ni: 75.0-80.0%, Mo: 3.6 to 4.5%, Cu: 4.5 to 5.5%, S: 15 ppm or less, O: 30 ppm or less, the balance being 11.0 to 14.0% Fe and inevitable impurities The Fe—Ni alloy plate having a composition with a Ni / Fe ratio of 5.6 to 6.1.
Preferably, the Fe—Ni based alloy plate is an Fe—Ni based alloy plate further containing Mg: 200 ppm or less.
Moreover, this invention can be set as the Fe-Ni type alloy board of initial magnetic permeability 300000 or more and maximum magnetic permeability 400000 or more by carrying out magnetic annealing of said Fe-Ni type alloy board.

Further, the present invention is a method for producing an Fe-Ni alloy plate having the above-described composition, a melting step for obtaining a steel ingot by vacuum melting, a soaking step for performing soaking after the melting step, and after the soaking step A hot rolling process for processing the Fe-Ni-based alloy into a plate shape by hot rolling, and a cold working process for performing cold rolling at a rolling rate of 60 to 85% after the hot rolling process, and This is a method for producing an Fe—Ni alloy plate that is not annealed during the cold working process.
Preferably, the Fe—Ni alloy is a method for producing an Fe—Ni alloy plate further containing Mg: 200 ppm or less.

The Fe—Ni-based alloy plate of the present invention can stably obtain magnetic characteristics of an initial permeability of 300000 or more and a maximum permeability of 400000 or more by combining an optimum composition capable of obtaining a high permeability, vacuum melting, and soaking. Can do.
In addition, it is not always necessary to use a specially shaped mold or the like, and the steel ingot can be enlarged, so that a wide Fe—Ni alloy having a width of 600 mm or more can be obtained, which is optimal as a magnetic shield material.

Of the elements defined in the present invention and their contents, the ratio of Ni and Fe and the high Mn content are the most important. First, Ni, Fe, and Mn will be described. In addition, all content of the element to prescribe is mass%.
Ni: 75.0-80.0%
The reason why Ni is set in the range of 75.0 to 80.0% is that this range is a range necessary for obtaining the high magnetic permeability aimed at by the present invention. In any case where the Ni content is less than 75.0% or more than 80.0%, the magnetic permeability decreases. A preferred range is 75.5 to 77.5%, and a more preferred range is 76.0 to 77.0%.
Fe: 11.0 to 14.0%
In the present invention, Fe is added as Ni and the balance of each additive element described later, but it is important to secure the content of Fe necessary for obtaining a high magnetic permeability as with Ni. In any case where the Fe content is less than 11.0% or more than 14.0%, the magnetic permeability decreases. Therefore, the Fe content needs to be 11.0 to 14.0%. Preferably, it is in the range of 11.5 to 13.5%, more preferably in the range of 12.3 to 13.3%.

Ni / Fe ratio: 5.6 to 6.1
It is important to obtain a high magnetic permeability by setting the ratio of Fe and Ni to a very limited range of 5.6 to 6.1 in terms of Ni / Fe ratio while ensuring the contents of Ni and Fe described above. It is.
Within this limited range, the magnetocrystalline anisotropy and magnetostriction can be made close to zero, and the magnetostriction becomes positive, so that deterioration of magnetic properties due to strain can be suppressed to a minimum. Further, the optimization of the Ni / Fe ratio makes it possible to obtain excellent magnetic permeability even when manufactured with a large steel ingot. A more preferable range of this Ni / Fe ratio is in the range of 5.7 to 6.05.
Mn: 1.3-2.0%
Mn is one of the important elements in the present invention for improving the magnetic properties, and is particularly effective for improving the magnetic permeability. Further, the positive addition of Mn makes it possible to obtain excellent magnetic permeability even when manufactured with a large steel ingot. Therefore, if the amount of Mn is less than 1.3%, the above effect cannot be obtained. On the other hand, if the amount of Mn exceeds 2.0%, inclusions are easily formed and the magnetic permeability is deteriorated. Therefore, Mn is set to 1.3 to 2.0%. Preferably, it is 1.4 to 1.9% of range.

Next, reasons for limitation other than the above-mentioned elements defined in the present invention will be described.
Mo: 3.6-4.5%
Mo improves the magnetic properties, and if Mo is 3.6 to 4.5%, the magnetic permeability is improved. If Mo is less than 3.6% or more than 4.5%, it is difficult to obtain the effect of improving the magnetic permeability. Therefore, Mo is set to 3.6 to 4.5%. Preferably it is 3.8 to 4.3% of range.
Cu: 4.5 to 5.5%
Cu is an element that improves DC magnetic characteristics, and in the present invention, it is necessary to add 4.5 to 5.5%. Since this effect is difficult to obtain in a range of less than 4.5% or in a range of more than 5.5%, Cu is set to 4.5 to 5.5%. Preferably it is 4.7 to 5.3%.
Si: 0.05-2.0%
Since Si has an effect of promoting the coarsening of crystal grains after magnetic annealing, it is added in the range of 0.05 to 2.0%. If Si exceeds 2.0%, inclusions are formed and the magnetic properties deteriorate, and if it is less than 0.05%, the effect of promoting the coarsening of crystal grains is lost. Therefore, Si was made 0.05 to 2.0%. A preferable range of Si is 0.07 to 1.0%.

C, S and O described below are impurities in the present invention.
C: 0.03% or less When C is positively added, growth of crystal grains after magnetic annealing is suppressed through the formation of carbides, and soft magnetic properties are deteriorated. Therefore, C is limited to a range of 0.03% or less. More preferably, it is 0.015% or less of range.
S: 15 ppm or less When S is positively added, growth of crystal grains after magnetic annealing is suppressed through the formation of sulfides, not only deteriorating soft magnetic properties but also degrading hot workability. Therefore, S is limited to a range of 15 ppm or less. More preferably, it is the range of 10 ppm or less.
O: 30 ppm or less O is present as an oxide inclusion, and if its content exceeds 30 ppm, crystal grain growth after magnetic annealing is inhibited, and improvement in magnetic permeability is inhibited. Therefore, O is limited to 30 ppm or less. More preferably, it is 15 ppm or less, More preferably, it is 10 ppm or less.

Mg: 200 ppm or less Mg is a selective element in the present invention, and is added in a range of 200 ppm or less as necessary. Mg is added as necessary to fix S which inhibits hot workability and improve hot workability. However, in the range where Mg exceeds 200 ppm, a further effect of improving hot workability of Mg cannot be expected. Therefore, the upper limit of Mg is 200 ppm. In order to more reliably obtain this hot workability improving effect, it is preferably in the range of 2 to 150 ppm, more preferably in the range of 5 to 100 ppm.
In the present invention, elements other than the elements described above are unavoidable impurities.
Inevitable impurities include elements such as P, N, and Cr that form a compound to suppress the coarsening of crystal grains, deteriorate hot workability, and deteriorate magnetic permeability. These inevitable impurities should be as small as possible.

Next, the manufacturing method of this invention is demonstrated.
When producing an Fe-Ni alloy having excellent permeability according to the present invention with a large steel ingot, the Fe content, Ni content, Ni / Fe ratio, and Mn content are optimized as described above. In addition, it is also important to reduce O and S in order to suppress the formation of inclusions that degrade the magnetic permeability. Since this can be realized together, in the present invention, a steel ingot is manufactured by vacuum melting. Apply the dissolution process.
As a method for producing an Fe—Ni alloy, there is a method of producing a continuous cast slab by continuous casting. However, since continuous casting is dissolved in the atmosphere, the O content increases and inclusions are easily formed. And since a cooling rate is quick and inclusions exist finely, it is easy to deteriorate magnetic permeability. Moreover, since component segregation is likely to occur in the central portion and fine inclusions are concentrated, the present invention produces a steel ingot by vacuum melting.

After the vacuum melting, a soaking process is performed. There are two timings for soaking, one is soaking the steel ingot, and the other is hot forging the steel ingot and after hot forging. Since this soaking is performed to improve component segregation, it is advantageous to perform the soaking after hot forging in consideration of the diffusion distance. The soaking temperature is preferably 1150 ° C to 1350 ° C, and the holding time is preferably 10 to 50 hours.
Next, a hot rolling process is performed in which the soaked Fe—Ni alloy is processed into a plate shape by hot rolling. Although the hot rolling process is not particularly limited, 60% to 85% cold rolling is performed using the hot rolled sheet after hot rolling as a raw material, and therefore the thickness of the final product and 60% to 85% by cold rolling. % Is required for the hot rolled sheet after hot rolling.

Next, cold rolling with a rolling rate of 60 to 85% is performed using the hot rolled sheet obtained by the hot rolling step. This cold rolling process is an important process for improving the magnetic permeability in the present invention.
When the cold rolling ratio is less than 60%, high magnetic permeability cannot be obtained by magnetic annealing performed to obtain desired magnetic characteristics. On the other hand, if the rolling rate exceeds 85%, the magnetic permeability is worsened. Therefore, the rolling rate of cold rolling is limited to a range of 60 to 85%. The rolling rate is 1-((sheet thickness at the end of cold rolling) / (material thickness starting cold rolling)).
Moreover, in this invention, annealing is not performed during this cold rolling process. This is because when annealing is performed, strain during cold rolling is released, and crystal grains are not sufficiently coarsened during magnetic annealing, so that high magnetic permeability cannot be obtained.
If the thickness of the hot-rolled sheet after the hot working process is not the same as that of the final product even if it is cold-rolled at a rolling rate of 60 to 85% due to mechanical equipment, It is preferable to perform the soft rolling annealing by performing the second cold rolling process, and to apply the cold working process in which the annealing is not performed at the rolling rate of 60 to 85% in the second cold rolling process.

As described above, the Fe—Ni-based alloy plate obtained by the manufacturing process described above has an optimum chemical component capable of obtaining a high magnetic permeability, is distorted by cold rolling, and is fine enough to prevent coarsening of crystal grains. Since there are few inclusions, when magnetic annealing is applied to this, an average crystal grain size grows to 400 μm or more, and an Fe—Ni alloy plate having an initial permeability of 300,000 or more and a maximum permeability of 400,000 or more can be obtained.
The magnetic annealing is performed in a reducing atmosphere, for example, 1000 to 1300 ° C., time 0.5 to 3 h, cooling rate 50 to 200 ° C./h.
In the present invention, since it is possible to manufacture with a large steel ingot, the width of the cold-rolled Fe-Ni alloy plate can be widened to 600 mm or more, and the initial permeability is 300,000 or more, the maximum Since it can achieve a magnetic permeability of 400,000 or more, it is optimal for magnetic shield applications.

A 6-ton steel ingot was obtained by melting an Fe-Ni alloy in which the Fe content, Ni content, Ni / Fe ratio, and Mn content were optimized by vacuum melting. No. 1 shown in Table 1 were produced. 1 and no. 2 is the present invention, No.2. 3 is a comparative example.
The obtained steel ingot was soaked at 1280 ° C. × 40 h in the air. The steel ingot was subjected to hot forging to form a slab, and the final dimension in the subsequent hot rolling was 4.5 mm (t) × 700 mm (w). Further, after removing the hot scale with a grinder, cold rolling was performed to 1.0 t (a cold rolling rate of 77.8%). Note that annealing was not performed during this cold rolling process.
A magnetic property measurement sample, a crystal grain measurement sample, and a chemical component measurement sample were collected from the Fe-Ni alloy plate after cold rolling. The chemical components are shown in Table 1.

Magnetic annealing was performed using this Fe-Ni alloy plate.
Magnetic annealing was performed in a hydrogen atmosphere with a dew point of −40 ° C. at 1100 ° C. × 3 h. Cooling was performed at 50 ° C./h, which is advantageous for obtaining high magnetic permeability, and taken out at 300 ° C.
Table 2 shows the initial permeability and the maximum permeability after the magnetic annealing.

No. of the present invention. In the case of 1 alloy plate, both the initial magnetic permeability and the maximum magnetic permeability exceeded 500,000. The results of the initial permeability of 300000 or more and the maximum permeability of 400000 or more were also obtained with the 2-alloy plate. On the other hand, a comparative alloy No. having a Ni / Fe ratio and an Mn amount outside the range of the present invention was used. In No. 3, the initial permeability of 300,000 or more and the maximum permeability of 400,000 or more could not be achieved.
Next, the present invention No. Using only one alloy, an experiment was conducted to determine whether high magnetic permeability can be obtained even in actual production. The cooling rate was increased to 100 ° C./h, and the initial permeability and maximum permeability after magnetic annealing were measured at treatment temperatures of 1000 ° C., 1050 ° C., 1100 ° C., and 1150 ° C. The treatment time was 3 hours in a hydrogen atmosphere with a dew point of −40 ° C.

  As shown in Table 3, even when the cooling rate was increased, the initial permeability of 300,000 or more and the maximum permeability of 400,000 or more could be achieved.

  The permalloy produced in the present invention has a high initial permeability and maximum permeability, and since a large steel ingot can be used, the width of the cold rolled material can be widened. This is suitable for applications requiring such a high initial permeability and a relatively wide plate.

Claims (5)

C: 0.03% or less by mass%, Si: 0.05 to 2.0%, Mn: 1.3 to 2.0%, Ni: 75.0 to 80.0%, Mo: 3.6 to 4.5%, Cu: 4.5 to 5.5%, S: 15 ppm or less, O: 30 ppm or less, the balance is 11.0 to 14.0% Fe and inevitable impurities, Ni / Fe ratio is An Fe-Ni alloy plate having a composition of 5.6 to 6.1. The Fe-Ni alloy plate according to claim 1, wherein the Fe-Ni alloy plate further contains Mg: 200 ppm or less.   The Fe-Ni alloy plate according to claim 1 or 2, wherein the Fe-Ni alloy plate has an initial permeability of 300,000 or more and a maximum permeability of 400,000 or more. C: 0.03% or less by mass%, Si: 0.05 to 2.0%, Mn: 1.3 to 2.0%, Ni: 75.0 to 80.0%, Mo: 3.6 to 4.5%, Cu: 4.5 to 5.5%, S: 15 ppm or less, O: 30 ppm or less, the balance is 11.0 to 14.0% Fe and unavoidable impurities, Ni / Fe ratio is A method for producing an Fe—Ni-based alloy sheet having a composition of 5.6 to 6.1,
A melting step of obtaining a steel ingot by vacuum melting;
A soaking step of performing soaking after the dissolving step;
A hot rolling process for processing the Fe—Ni-based alloy after the soaking process into a plate shape by hot rolling;
A Fe—Ni-based alloy sheet comprising: a cold working step in which cold rolling is performed at a rolling rate of 60 to 85% after the hot rolling step, and annealing is not performed during the cold working step. Manufacturing method. The method for producing an Fe-Ni alloy plate according to claim 4, wherein the Fe-Ni alloy further contains Mg: 200 ppm or less.