JPH0261027A - Ni-fe-cr high permeability magnetic alloy having excellent hot workability - Google Patents

Abstract

PURPOSE:To obtain the title magnetic alloy at low cost by specifying the compsn. constituted of C, Si, Mn, P, S, Al, Ni, Cr, B and Fe. CONSTITUTION:The Ni-Fe-Cr high permeability magnetic alloy having hot workability contains <=0.01% C, <=2.0% Si, <=5.0% Mn, <=0.02% P, <=0.01% S, <=0.10% Al, 70.0 to 85.0% Ni, 0.5 to 10.0% Cr, 0.002 to 0.020% B and the balance Fe with inevitable impurities. In the above magnetic alloy, permeability and hot workability are improved by incorporating specific amt. of B thereto and reducing the content of S and Al. By this method, the generation of flaws at the time of hot rolling is prevented and the yield of the manufactures is improved without impairing the magnetic characteristics of the above alloy.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a Ni-Fe-Cr alloy with excellent hot workability that is used as a high permeability magnetic alloy.

(Prior art and its problems) Ni-Fe-Cr based high permeability magnetic alloys have many uses as materials for electronic devices, such as shield case materials and head bore materials for audio and VTRs, and core and yoke materials for high-end transformers. There is.

With the development of electronic and electromagnetic industries in recent years, %'l1-Fs
-Cr-based high permeability magnetic alloy family As permeability magnetic alloys become smaller and more sophisticated, it is desired to further improve the characteristics of such high permeability magnetic alloys.

However, the Ni-Fe-Cr based high permeability magnetic alloy has extremely poor hot workability. That is, many cracks may occur when the steel is rolled or hot rolled. Therefore, there are problems in that the product yield is significantly reduced and manufacturing costs are increased.

Therefore, in order to reduce manufacturing costs, it is necessary to prevent cracks during hot working and improve hot workability.

The causes of cracking during hot working of such Ni-Fe-Cr based high permeability magnetic alloys include segregation of impurities such as A1, S, and P, and grain boundary precipitation of oxides, sulfides, and nitrides. This may be due to embrittlement. But Al.

Even if the S content is low, cracks often occur and the product yield may decrease.A Ni-Fe-Cr based high permeability magnetic alloy with excellent hot workability can solve this problem. was desired.

(Knowledge related to problem solving) The present invention aims to obtain high magnetic permeability and excellent hot workability, and as a result of various studies on the composition of Ni-Fe-Cr based high permeability magnetic alloys in order to solve the problems, we have identified It has been found that high magnetic permeability and excellent hot workability can be obtained by containing a certain amount of B and reducing the S and A1 contents.

(Structure of the invention) The above purpose is C: 0.01% or less.

Si: 2.0% or less.

Mn: 5.0% or less.

P: 0.02% or less.

S: 0.01% or less.

, H:　o,io% or less.

Ni: 70. Q~85.0%.

Cr: 0.5-10.0%.

B: 0.002-0.020%.

This is achieved by a Ni-Fe-Cr based high permeability 8i magnetic alloy with excellent hot workability, the balance being Fe and unavoidable impurities.

Next, the reason why the composition of the Ni-Fe-Cr based high permeability magnetic alloy is limited in the present invention will be explained below.

Since C lowers magnetic permeability, it was set to 0.01% or less.

Sl is necessary for deoxidation, but if it exceeds 2.0%, the magnetic permeability decreases, which is undesirable, so it is set to 2.0% or less.

,'! n is effective in deoxidizing and improving hot workability. In addition, it is added to suppress the sensitivity of magnetic properties to the cooling rate during annealing, but if the content exceeds 5.0%, the saturation magnetic flux density and Bi permeability will decrease, making it impractical. It was set to 5.0% or less.

Since P and S are elements that deteriorate hot workability, they were set to 0.02% or less and 30.01% or less, respectively.

A1 is necessary for deoxidation, but since it is an element that deteriorates hot workability if it exceeds 0.10%, it was set to 0.10% or less.

Ni is limited to 70.0 to 85.0% because high magnetic permeability cannot be obtained outside the range of 70.0 to 85.0%.

If Cr is less than 0.5%, it has no effect of suppressing the formation of a regular lattice in the alloy, and furthermore, the effect of improving magnetic properties is small.

Moreover, if it exceeds 10.0%, the saturation magnetic flux density and magnetic permeability will decrease, so it is set at 0.5 to 10.0%.

B is one of the most important elements in the present invention, which has been found to eliminate cracks during hot rolling and improve manufacturability by adding an appropriate amount to a Ni-Fe-Cr based high permeability magnetic alloy. be. The appropriate amount is 0.002-0.020%
Within the range of 0.002%, there is no effect;
If added in excess of 0.020%, the boride will precipitate and the effect will be lost, so the amount was set at 0.002 to 0.020%.

(Specific Disclosure of the Invention) A Ni-Fe-Cr based high permeability magnetic alloy having the chemical composition shown in Table 1 was melted in a high frequency vacuum melting furnace to form a 30 kg steel ingot. A test piece was cut from the melted steel ingot and its hot workability was investigated.

A high temperature tensile test was conducted as an evaluation test for hot workability. That is, after heating a test piece with a diameter of 10 m to a tensile test temperature of 800 to 1200'C, a tensile test was conducted at a strain rate of 1/sea until fracture, and the cross-sectional shrinkage rate was measured to evaluate hot workability.

Figure 1 shows the relationship between hot workability and Ni and Cr contents.
% to 84.1%, Cr content 0.9% to 8.7%
The alloys shown above show the same tendency, indicating that they can be considered to be in the same category as far as hot workability is concerned in the present invention.

FIGS. 2 and 3 show the influence of B on hot workability. According to this, sample Na containing 0.003% B
1-8 has a cross-sectional shrinkage rate of over 70% at 800°C, and sample Nα1-10 (0,
007%B), sample NQ 1-3 (0,015%B)
etc., the cross-sectional shrinkage rate exceeds 80% in the entire temperature range of 800 to 1200°C. However, in sample Nα1-11 (0,022% B), which has an even higher B content, the cross-sectional shrinkage rate decreases to the same level as that in which B is not added.

Therefore, B O,002~0.0 with limited component composition
It can be seen that addition of 20% increases cross-sectional shrinkage and improves hot workability.

EXAMPLES Based on the results shown in FIGS. 1 to 3, the alloys of the present invention and comparative alloys whose compositions were limited were melted by vacuum melting. Table 2 shows the compositions of the invention alloy and comparative alloy. The obtained flat ingot with a thickness of 130 mm was hot-rolled into a hot-rolled plate with a thickness of 4Iff11, and then roughly cold-rolled into a cold-rolled thin plate with a thickness of 1.0m, which was then rolled into a sheet with an outer diameter of 45 m and an inner diameter of 33 nn. It was processed into a ring according to JIS 2531 and used as a sample.

The above sample was heat treated at 1100℃ for 2 hours in a hydrogen atmosphere and cooled in a furnace. The appearance conditions shown in the table were evaluated based on the presence or absence of edge cracks and surface flaws in the hot rolled sheets.

From Table 3, it is clear that when B is added in a limited amount according to the present invention, it is possible to obtain a good hot-rolled material with no cracks during hot rolling, and also to produce a material with excellent magnetic properties. It became.

We were able to prevent cracks during hot rolling without impairing the magnetic properties of the Ni-Fe-Cr based high permeability magnetic alloy, making it possible to significantly improve the product yield. became. That is, it has become possible to manufacture a Ni-Fe-Cr based high permeability magnetic alloy at low cost.

[Brief explanation of the drawing]

Figure 1 shows Ni-Fe-Cr based high permeability magnetic alloy,
The figure which shows the relationship between Cr content, tensile test temperature, and cross-sectional shrinkage rate. FIGS. 2 and 3I2I are diagrams showing the relationship between the tensile test temperature and the cross-sectional shrinkage rate when B is added to the J i -Fe-Cr family permeable 4I magnetic alloy. (Effects of the present invention) In view of the fact that the hot workability of conventional Ni-Fe-Cr based high permeability magnetic alloys is extremely poor, the present invention limits the component composition, and in particular B is 0.002 to 0.020. % addition, the following effects could be obtained.

Claims (1)

[Claims] C: 0.01% or less, Si: 2.0% or less, Mn: 5.0% or less, P: 0.02% or less, S: 0.01% or less, Al: 0. Contains 10% or less, Ni: 70.0 to 85.0%, Cr: 0.5 to 10.0%, B: 0.002 to 0.020%, with the remainder consisting of Fe and inevitable impurities. A Ni-Fe-Cr based high permeability magnetic alloy with excellent hot workability.