JPH05255817A - Corrosion resistant soft magnetic material - Google Patents

Abstract

PURPOSE:To provide a soft magnetic alloy material capable of stably obtaining >=10000 maximum magnetic permeability and good in corrosion resistance as well by particularly regulating impurities in ferritic stainless steel. CONSTITUTION:This corrosion resistant soft magnetic material has a fundamental compsn. contg., by weight, <=0.02% C, <=0.02% N, 0.5 to 2.0% Si, <=0.5% Mn, <=0.03% P, 8 to 20% Cr and 0.5% Ni, and the balance Fe, and contg. only <=0.05% Al, <=0.05% Ti, <=0.003% S and <=0.005% O as well as satisfying <=0.006% S+O and having >=10000 maximum magnetic permeability (mum). In addition to the regulation of the content of Al, Ti, S and O, the total of S+O is regulated to <=0.006%, by which excellent magnetic properties can stably be obtd.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a Fe--Cr soft magnetic material suitable for magnetic shields used in corrosive environments, transformer cores, various motor cores, etc. and having improved magnetic characteristics.

[0002]

2. Description of the Related Art Ferritic stainless steel sheets have been known as corrosion-resistant soft magnetic materials, and are widely used for magnetic shield members, motor iron core parts and the like. However, the magnetic properties of ferritic stainless steel are significantly inferior to those of electromagnetic soft iron, Fe-Ni alloy, etc. in terms of magnetic permeability and coercive force.

In order to improve the magnetic characteristics of ferritic stainless steel, it is intended to improve the magnetic permeability and coercive force by adding Si and Ti to the Fe-Cr alloy to reduce C and O. No. 39-20644. However, when Si, Ti, etc. are added, it is difficult to stably obtain magnetic characteristics such as high magnetic permeability and low coercive force. Further, the influence of impurities such as impurities O and N on the magnetic characteristics is unknown.

Japanese Patent Publication No. 50-37135, Japanese Patent Publication No. 5135
In Japanese Patent Laid-Open No. 4-14569, the amount of C and N in the steel is reduced by annealing at high temperature for a long time, and the magnetic properties are improved by imparting directionality. However, this method is costly because the process is complicated and annealing for a long time is required.

Further, in Japanese Patent Laid-Open No. 186854/1988, the impurities contained in the material are C: 0.01% by weight or less, N: 0.03% by weight or less, Si: 0.1% by weight or less. The magnetic permeability is increased by reducing the above. However, even if these impurities are reduced, the maximum magnetic permeability μ _m of the obtained magnetic material is no more than about 5,000.

[0006]

As described above, according to the prior art, even if many element additions, manufacturing processes, and annealing conditions are restricted, it is possible to obtain industrially stable maximum magnetic permeability of 10,000 or more. Not in.

In the present invention, by preparing each component including impurities such that the magnetic characteristics are low, the maximum magnetic permeability of 10,000 or more of the magnetic characteristics can be stably obtained. It is an object to provide a Cr-based corrosion resistant soft magnetic alloy.

[0008]

In order to achieve the object, the corrosion resistant soft magnetic material of the present invention has a C content of 0.02% by weight.
Below, N: 0.02% by weight or less, Si; 0.5 to 2.0
% By weight, Mn: 0.5% by weight or less, P: 0.03% by weight
Hereinafter, Cr: 8 to 20% by weight, Ni: 0.5% by weight, the basic composition consisting of the balance Fe, Al: 0.05
Wt% or less, Ti: 0.05 wt% or less, S: 0.00
3% by weight or less and O: 0.005% by weight or less, and S
+ O: maximum permeability satisfying the 0.006 percent mu _m
Is 10,000 or more.

[0009]

The inventors of the present invention have conducted extensive research on the effect of impurity elements in order to develop a corrosion-resistant soft magnetic alloy exhibiting excellent magnetic permeability. As a result, in the Fe-Cr alloy, Si, which is effective in improving the soft magnetic characteristics, is added, and A
It has been found that the soft magnetic characteristics can be significantly improved by reducing l and Ti and controlling the S content and the O content.

The alloy components and their contents in the present invention will be described in detail below. C: Carbide is easily formed and magnetic properties and corrosion resistance are deteriorated, so the content is limited to 0.02% by weight or less. N: A nitride is formed with Al, Ti, etc., and magnetic properties are greatly deteriorated. Therefore, the upper limit of the N content is set to 0.02% by weight.

Si: An effective alloying element for improving magnetic properties and corrosion resistance. When Si is less than 0.5% by weight, the effect of improving magnetic permeability and coercive force is small. However, if it exceeds 2% by weight, the effect of improving the magnetic properties is saturated and, conversely, the press punchability and the formability are greatly reduced. Therefore, S
The i content was set in the range of 0.5% by weight to 2.0% by weight.

Mn: Does not contribute to the improvement of magnetic permeability and is 0.5
If it exceeds 5% by weight, the saturation magnetic flux density is lowered. Therefore,
The upper limit of the Mn content was 0.5% by weight. P: Since it is a harmful element that deteriorates magnetic permeability and coercive force, it was limited to 0.03% by weight or less.

Cr: An alloying element effective for improving the corrosion resistance, and also a ferrite-forming element, and therefore effective for improving soft magnetism. When the Cr content is less than 8% by weight,
No corrosion resistance effect is seen against oxidative corrosion. But,
When the Cr content exceeds 20% by weight, the saturation magnetic flux density is significantly reduced. Therefore, in the range of 8 to 20% by weight Cr
The content was regulated.

Ni: An austenite forming element, which does not contribute to the improvement of magnetic permeability. Ni content is 0.5% by weight
When it exceeds, the saturation magnetic flux density is lowered. Therefore, N
The upper limit of the i content was 0.5% by weight.

Al and Ti: Elements added as a deoxidizing agent, which have the effect of reducing impurities along with deoxidation and improving magnetic properties. However, excessive addition of AlN, T
A nitride such as iN is formed to suppress the growth of crystal grains. As a result, magnetic permeability and coercive force deteriorate. Therefore, the upper limits of both the Al content and the Ti content are restricted to 0.05% by weight.

S and O: Impurity elements S and O are
They easily form sulfides and oxides, respectively, and prevent the coarsening of crystal grains during magnetic annealing and the movement of domain walls.
As a result, the magnetic permeability is greatly reduced. Therefore, the upper limit of S content is 0.003 wt% and the upper limit of O content is 0.
It was defined as 005% by weight, respectively.

Further, as an alloy system in this component range, Fe
When the relationship between S + O and the maximum magnetic permeability was examined for the -13.0 wt% Cr alloy steel, it was found that the relationship shown in FIG. 1 was established between the two. That is, S + O is 0.
It has been found that when the amount exceeds 006% by weight, the maximum magnetic permeability μ _m sharply decreases to 10,000 or less. From this, in the present invention, the upper limit of S + O is defined as 0.006% by weight.

[0018]

EXAMPLES Using a normal vacuum melting furnace, various Fe-Cr alloys having the compositions shown in Table 1 were melted and cast into ingots. Then, forging, hot rolling, and cold rolling were performed to manufacture a plate having a plate thickness of 1 mm. Test number 1 in Table 1
~ 14 are alloys according to the invention. In addition, test numbers 15 to 25 in Table 2 are comparative alloys in which the content of at least one of the alloy components is out of the range of the present invention.

[0019]

[Table 1]

[0020]

[Table 2]

A ring-shaped test piece having an outer diameter of 45 mm and an inner diameter of 33 mm was cut out from each cold-rolled sheet having the composition shown in Table 1 and Table 2, magnetic annealing was performed at 900 ° C. for 2 hours, and then a DC magnetic measurement was performed. went. The results are shown in Table 3.

Each test piece was subjected to a salt spray test for 24 hours in accordance with JIS Z2371 to investigate the corrosion resistance. Corrosion resistance test results, visually observing that almost no rust was found, ○, lightly distributed point rust was △, area ratio of rust of 10 wt% or more was judged as ×, It is also shown in Table 3.

[0023]

[Table 3]

As is clear from Table 3, the alloys of the present invention 1 to
Each of 14 has a high maximum magnetic permeability μ _m of 10,000 or more, and has excellent magnetic characteristics with low coercive force. Also,
The corrosion resistance was also good. On the other hand, Comparative Alloys 15 to 25 whose component contents deviate from the ranges specified in the present invention
, The maximum magnetic permeability μ _m , coercive force, and corrosion resistance were inferior.

[0025]

As described above, in the present invention, by balancing the alloy components including impurities, Ti, Al and the like, the maximum magnetic permeability μ _{m of} 10,000 or more can be stably obtained, In addition, a soft magnetic material having excellent corrosion resistance can be obtained. This corrosion-resistant soft magnetic material is used as a magnetic shield member, an iron core for various motors, and the like.

[Brief description of drawings]

FIG. 1 is a diagram showing a relationship between S + O and maximum magnetic permeability.

Claims (1)

[Claims] 1. C: 0.02% by weight or less, N: 0.02% by weight or less, Si; 0.5 to 2.0% by weight, Mn: 0.5
Wt% or less, P: 0.03 wt% or less, Cr: 8 to 20
%, Ni: 0.5% by weight, with a basic composition consisting of the balance Fe, Al: 0.05% by weight or less, Ti:
0.05% by weight or less, S: 0.003% by weight or less and O: 0.005% by weight or less, and S + O: 0.006
A corrosion-resistant soft magnetic material having a maximum magnetic permeability μ _m of 10,000 or more, which satisfies the weight% or less.