JPH11209854A - Composite magnetic material having ferromagnetic part and nonmagnetic part and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a composite magnetic material having a high detection sensitivity and improved strength by preparing a steel having a componental compsn. contg. specified ratios of C, Si, Mn, Ni, Cr, Mo and Al and satisfying specified Md30 value and equivalent Heq value and having a specified ferromagnetic part and nonmagnetic part. SOLUTION: A composite magnetic material having a componental compsn. of steel contg., by weight, <=0.1%, C, <=1.0% Si, <=1.5% Mn, 6.0 to 12.0% Ni, 12.0 to 20.0% Cr, <=2.0% Mo, 0.5 to 2.0% Al, and the balance Fe with inevitable impurities and satisfying the formula of Angel: md30=413-462(C%+N%)-92(Si%)-8.1(Mn%)-13.7 (Cr%)-9.5(Ni%)-18.5(Mo%)=20 to 90 deg.C and the Ni equivalent of the formula of Hirayama Heq=(Ni%)+1.05(Mn%)+0.65(Cr%)+0.36(Si%)+12.6(C%)=19 to 23% and having a ferromagnetic part with >=0.3T magnetic flux density B50 and a nonmagnetic part with <=1.2 permeability is prepd.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a composite magnetic material having a combination of a ferromagnetic portion and a non-magnetic portion used for a fuel injection valve and the like, and a method of manufacturing the same. The present invention relates to a composite magnetic material having both a ferromagnetic portion and a non-magnetic portion, both of which are made ferromagnetic and then a part of which is heat-melted to make it non-magnetic, and a method of manufacturing the same.

[0002]

2. Description of the Related Art Conventionally, a composite magnetic material having a combination of a ferromagnetic part and a non-magnetic part has been used as a magnetic scale in a mechatronics field for a position detecting mechanism, and has recently been proposed for use in a fuel injection valve. I have. One of the methods for producing this composite magnetic material includes Cr and Ni,
Alternatively, in a metastable austenitic steel further containing Mo, Md = 413─462 × (C + N) ─9.2 Si─8.1
When the Md value represented by the formula of Mn─13.7Cr─9.5Ni─18.5Mo is 15 ° C. or more, 2Ni + 100 × (N +
C) A composite magnetic material in which a material having a component composition satisfying the condition of -Cr ≧ 2.0 is cold drawn to be ferromagnetic, and a local portion is heat-melted to make it non-magnetic and a method for producing the same are disclosed in
No. 161146. However, this composite magnetic material has a problem that the specific electric resistance value of the ferromagnetic portion is low, and thus the detection sensitivity is low.

Also, C: 0.6% or less, Cr: 12-1
9%, Ni: 6 to 12%, Mn: 2% or less, Mo: 2%
In the following, Nb: 1% or less, composed of the balance of Fe and unavoidable impurities. Hirayama's equivalent Heq = (Ni%) + 1.05 (Mn%) + 0.65 (Cr%) + 0.36 (Si%) + 12.6 (C %) = 20 to 23%, nickel equivalent Nieq = (Ni%) + 30 (C%) + 0.5 (Mn%) = 9 to 12%, and chromium equivalent Cr = (Cr%) + ( Mo%) + 0.5 (Si%) + 0.5 (Nb%) = 16 to 19% The number of processing steps for applying strain to a material having a composition of 16 to 19% is increased, and the temperature of each processing step is set to 100 ° C. Within this range, a ferromagnetic part having a magnetic flux density B ₄₀₀₀ of 0.3 T (tera) or more is provided, and a part of the ferromagnetic part is
Japanese Patent Application Laid-Open No. 8-3643 discloses a method for producing a composite magnetic member in which a solution is heated and melted within seconds to reduce the crystal grain size to 30 μm or less. However, this composite magnetic material can maintain ferromagnetism and non-magnetism even in a very low temperature environment. However, as in JP-A-63-161146, the specific electric resistance of the ferromagnetic portion is low, and the detection sensitivity is low. Is low.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to provide a composite magnetic material having both a ferromagnetic portion and a non-magnetic portion having high detection sensitivity for a ferromagnetic portion and having high strength, and a method for producing the same. I do.

[0005]

In order to solve the above-mentioned problems, in the composite magnetic material of the present invention having both a ferromagnetic portion and a non-magnetic portion, C: 0.1% or less, Si: 1.0% or less. , Mn: 1.5% or less, Ni: 6.0 to 12.0%,
Cr: 12.0 to 20.0%, Mo: 2.0% or less, A
l: 0.5 to 2.0%, and if necessary, Nb:
A ferromagnetic part containing not more than 2.0%, the balance being Fe and unavoidable impurities, having a steel composition satisfying the following formulas 1 and 2, and having a magnetic flux density B50 of 0.3 T (tera) or more; 1.2 or less non-magnetic portion. Formula 1 Formula of Angel Md30 = 413 ─462 (C% + N%) ─9.2 (Si%) ─8.1 (Mn%) ─13.7 (Cr%) ─9.5 (Ni%) ─18.5 (Mo%) = 20 to 90 ° C. Formula 2 Hirayama's equivalent Heq = (Ni%) + 1.05 (Mn%) + 0.65 (Cr%) + 0.36 (Si%) + 12.6 (C%) = 19-23%

In order to solve the above-mentioned problems, a method of manufacturing a composite magnetic material having a ferromagnetic part and a non-magnetic part according to the present invention is characterized in that C: 0.1% or less, Si: 1.0% or less, Mn: 1.5% or less, Ni: 6.0 to 12.0%,
Cr: 12.0 to 20.0%, Mo: 2.0% or less, A
l: 0.5 to 2.0%, and if necessary, Nb:
A steel containing 2.0% or less, the balance being Fe and unavoidable impurities, and having a component composition satisfying the above formulas 1 and 2, is cold-worked, and then, if necessary, is subjected to aging precipitation treatment to obtain a magnetic flux density B50 of 0.1%. A ferromagnetic portion of 3T or more is formed, and a part of the ferromagnetic portion is heated to a solution to be demagnetized.

The present invention will be described in detail. The steel having the above-described composition of the composite magnetic material of the present invention is produced by a usual method for producing this type of steel, for example, hot forging after melting in a vacuum induction furnace.
It can be manufactured by a method of hot rolling into a plate or bar. If tubes are needed, use the usual manufacturing method,
For example, it can be manufactured by bending and welding a plate material. Further, the cold working of the present invention can be performed by cold rolling, cold drawing, cold drawing, cold ironing, or the like. The processing rate is such that B50 becomes 0.3T or more, for example, 30% or more. Note that the processing rate is specified by the result in this way because the processing rate differs depending on the composition of the steel, which is the material, whether or not to perform the aging precipitation treatment, the magnetic flux density to be obtained, etc., so it cannot be determined unconditionally. It is. Further, the aging precipitation treatment of the present invention is performed at 450 to 780 ° C. for 30 minutes.
Heat for 100 minutes and air-cool, or then 500-
The heating is preferably performed at 600 ° C. for 80 to 400 minutes.
The solution heat treatment of the present invention can be performed by any method as long as it can heat only the portion of the member to be demagnetized without melting, but it is easy to perform high-frequency heating.

Next, the reason why the component composition and the like are limited as described above in the composite magnetic material having the ferromagnetic portion and the non-magnetic portion of the present invention and the method for producing the same will be described. C: 0.1% or less C is an interstitial element and contributes to the improvement of strength. However, when added in a large amount, it combines with Cr to form carbides and lowers the amount of solute Cr in the matrix. Therefore, the upper limit is set to 0.1%.

Si: 1.0% or less Si is an element mainly required as a deoxidizing agent during refining, but if contained in a large amount, the hot workability is reduced, so the upper limit is 1.0%. And Mn: 1.5% or less M
n is an element that forms austenite to make it non-magnetic, fixes S as MnS, and improves hot workability. However, even if it exceeds 1.5%, the effect is not increased.
In addition, the cost of the material increases, so the upper limit is 1.5%.
And

Ni: 6.0 to 12.0% Ni is an element that forms austenite to make it non-magnetic, contributes to the stability of the austenite phase, reduces deformation resistance, and further improves workability at low temperatures. If the content is less than 6.0%, these effects, in particular, the relative magnetic permeability does not become 1.2 or less. Since the effect of improving corrosion resistance is saturated, the content range is set to 6.0 to 12.0%.

Cr: 12.0 to 20.0% Cr improves the corrosion resistance of stainless steel,
It is an element that increases the magnetic flux density of stainless steel when cold worked, but if it is less than 12.0%, the corrosion resistance and magnetic flux density do not become sufficiently high, and if it exceeds 20.0%, a ferrite-austenite two-phase structure is formed. Therefore, the content range is from 12.0 to 20.
0%. Mo: 2.0% or less Mo is an element effective in increasing the strength and lowering the Ms point. However, if it exceeds 2.0%, an excessive amount of ferrite may be generated. 0.0%. Preferably it is 0.1-1.8%.

Al: 0.5% to 2.0% Al increases the specific electric resistance, increases the hardness of the material by precipitation hardening, increases the strength, and reduces oxygen that adversely affects the magnetic properties. Therefore, the content range is set to 0.5 to 2.0%. Nb: 2.0% or less Nb is an element to be added as necessary because it contributes to refinement of crystal grains and improvement in strength. However, if Nb is contained in a large amount, formability is reduced. %.

Angel equation Md30 (° C.) = 20-9
If the formula Md30 (° C.) of 0 ° C. Angel is lower than 20 ° C., the B50 of the ferromagnetic portion does not become 0.3 T or more even if the degree of cold working is increased, and if it becomes higher than 90 ° C., it becomes a heated solution. This is because the relative magnetic permeability of the non-magnetic portion does not fall below 1.2. Hirayama's equivalent Heq = 19-23% When Heq is lower than 19%, the relative magnetic permeability of the non-magnetic portion is 1.2.
If the Heq is greater than 23%, the austenite is stable, and the B50 of the magnetic flux density does not become 0.3T or more even when the cold working ratio is increased. I do.

Next, the reason why the magnetic flux density B50 of the ferromagnetic portion of the composite magnetic material of the present invention is set to 0.3 T or more and the non-magnetic portion is set to a magnetic permeability of 1.2 or less will be described. When used in a fuel injection valve or the like, if the B50 of the ferromagnetic portion is 0.3 T or more, the magnetism (%) generated from the solenoid or the like does not significantly decrease by passing through it. If the magnetic permeability of the non-magnetic portion is 1.2 or less, magnetism generated from a solenoid or the like can be sufficiently cut off.

[0015]

Embodiments of the present invention will be described below. Example 1 Steels of the present invention and comparative examples having the component compositions shown in Table 1 below were melted in a vacuum induction furnace, and then cast and rolled to produce a plate having a thickness of 2 mm and a width of 400 mm. These plates are cut to a predetermined width and bent to an outer diameter of 30 mm.
ERW tube. This tube was annealed at 950 ° C. and softened, and then subjected to cold drawing at a working ratio of 50% to obtain an outer diameter of 28 mm.
X A tube having a thickness of 1 mm was used.

[0016]

[Table 1]

Using the cold-drawn pipe as a test material, the magnetic flux density B50 and the specific electrical resistance were measured. The results were shown in Table 2 below in the column of magnetic properties B50 of 50% cold-worked material and the specific electrical resistance. It is described in the column of resistance value. Further, a test piece having a length of 3 mm was cut out from the tube subjected to the cold drawing, and the test piece was heated and cooled with water at 1050 ° C. for 30 minutes to form a solution. The magnetic permeability was measured using the solution-treated test pieces, and the results are shown in the column of magnetic permeability in Table 2 below.

[0018]

[Table 2]

From these results, all of the examples of the present invention have a magnetic flux density B50 of 0.3 T or more and a magnetic permeability of 1.2 or less, and have the performance required for a composite magnetic material used for a fuel valve or the like. The specific electrical resistance value affecting the detection sensitivity was 61 μΩ / cm or more. In contrast, Al
In Comparative Example No. 11 having a magnetic flux density B50 of less than 0.5% and a magnetic flux density B50 of 0.7 T or more but 0.3 T or more, the magnetic permeability was as high as 1.21 and was sufficient as a composite magnetic material. It was not something. Further, the specific electrical resistance value affecting the detection sensitivity was as low as 51 μΩ / cm. Also, in Comparative Example No. 12 in which Al was less than 0.5%, the magnetic flux density B50 was 0.2 T or less and 0.3 T or less, and the magnetic permeability was as high as 1.24. It did not have the required performance for magnetic materials. The specific electrical resistance value affecting the detection sensitivity was as low as 52 μΩ / cm. Table 1 in Example 1 shows Pickering for steels of the present invention and comparative examples.
The temperature at the Ms point calculated by the following equation is described. However, when manufacturing equipment to be used in a cold region, it is necessary to use a device having a low Ms point, so the Ms point is also described.

Example 2 No. 2 of the present invention of Example 1 and No. 12 of the comparative example were subjected to cold drawing of 30% and 50% under the conditions shown in Table 3. Aging precipitation treatment and magnetic flux density B
50 were measured, and the results are shown in Table 4. Further, the test materials of No. 2 of the present invention and No. 12 of the comparative example were subjected to cold drawing of 30%, and then subjected to aging precipitation treatment under the conditions shown in Table 3, and the hardness was measured. Are shown in Table 4.

[0021]

[Table 3]

[0022]

[Table 4]

From these results, it can be seen that the No. 2 experimental material of the present invention, when subjected to a proper aging precipitation treatment, has an improved hardness (strength) and a higher magnetic flux density B50.
950 is 30% cold-worked, about 2.7 times,
50% cold-worked, 2.4 times larger.
On the other hand, in the experimental material of Comparative Example No. 12, the hardness (strength) was reduced by the aging treatment, and the B50 of the magnetic flux density was hardly changed as a whole.

[0024]

The composite magnetic material of the present invention and the method for producing the composite magnetic material according to the present invention have the following excellent effects by adopting the above-mentioned structure. (1) A composite material having a magnetic flux density B50 of 0.3 T or more is obtained. (2) Since the electric resistance is sufficiently high, a composite material having good detection sensitivity can be obtained. (3) By performing the aging precipitation treatment, the strength can be improved and the magnetic flux density B50 can be increased.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code FI F02M 51/06 F02M 51/06 S H01F 1/00 H01F 1/00 Z

Claims (4)

[Claims] 1. In weight% (the same applies hereinafter), C: 0.1% or less, Si: 1.0% or less, Mn: 1.5% or less, Ni:
6.0 to 12.0%, Cr: 12.0 to 20.0%, M
o: 2.0% or less, Al: 0.5 to 2.0%, balance Fe
And a steel composition containing unavoidable impurities and satisfying the following formulas 1 and 2, and having a magnetic flux density B50 of 0.3 T
A composite magnetic material having both a ferromagnetic portion and a nonmagnetic portion, wherein the composite magnetic material has the above ferromagnetic portion and a nonmagnetic portion having a magnetic permeability of 1.2 or less. Formula 1 Formula of Angel Md30 = 413 ─462 (C% + N%) ─9.2 (Si%) ─8.1 (Mn%) ─13.7 (Cr%) ─9.5 (Ni%) ─18.5 (Mo%) = 20 to 90 ° C. Formula 2 Hirayama's equivalent Heq = (Ni%) + 1.05 (Mn%) + 0.65 (Cr%) + 0.36 (Si%) + 12.6 (C%) = 19-23% 2. C: 0.1% or less, Si: 1.0% or less, Mn: 1.5% or less, Ni: 6.0 to 12.0%,
Cr: 12.0 to 20.0%, Mo: 2.0% or less, A
l: 0.5 to 2.0%, Nb: 2.0% or less, balance Fe
And a steel composition containing unavoidable impurities and satisfying the following formulas 1 and 2, and having a magnetic flux density B50 of 0.3 T
A composite magnetic material having both a ferromagnetic portion and a nonmagnetic portion, wherein the composite magnetic material has the above ferromagnetic portion and a nonmagnetic portion having a magnetic permeability of 1.2 or less. Formula 1 Formula of Angel Md30 = 413 ─462 (C% + N%) ─9.2 (Si%) ─8.1 (Mn%) ─13.7 (Cr%) ─9.5 (Ni%) ─18.5 (Mo%) = 20 to 90 ° C. Formula 2 Hirayama's equivalent Heq = (Ni%) + 1.05 (Mn%) + 0.65 (Cr%) + 0.36 (Si%) + 12.6 (C%) = 19-23% 3. C: 0.1% or less, Si: 1.0% or less, Mn: 1.5% or less, Ni: 6.0 to 12.0%,
Cr: 12.0 to 20.0%, Mo: 2.0% or less, A
l: 0.5 to 2.0%, and if necessary, Nb:
A steel containing 2.0% or less, the balance being Fe and unavoidable impurities, and having a component composition satisfying the following formulas 1 and 2 is cold worked to form a ferromagnetic portion having a magnetic flux density B50 of 0.3 T or more. A method for producing a composite magnetic material having both a ferromagnetic part and a non-magnetic part, wherein a part of the magnetic part is heat-fused into a non-magnetic part. Formula 1 Formula of Angel Md30 = 413 ─462 (C% + N%) ─9.2 (Si%) ─8.1 (Mn%) ─13.7 (Cr%) ─9.5 (Ni%) ─18.5 (Mo%) = 20 to 90 ° C. Formula 2 Hirayama's equivalent Heq = (Ni%) + 1.05 (Mn%) + 0.65 (Cr%) + 0.36 (Si%) + 12.6 (C%) = 19-23% 4. C: 0.1% or less, Si: 1.0% or less, Mn: 1.5% or less, Ni: 6.0 to 12.0%,
Cr: 12.0 to 20.0%, Mo: 2.0% or less, A
l: 0.5 to 2.0%, and if necessary, Nb:
A steel containing 2.0% or less, the balance being Fe and unavoidable impurities, and having a component composition satisfying the following formulas (1) and (2) is cold-worked, and then subjected to age precipitation treatment to obtain a magnetic flux density B50 of 0.
A method of manufacturing a composite magnetic material having a combination of a ferromagnetic portion and a nonmagnetic portion, wherein the ferromagnetic portion has a ferromagnetic portion of 3T or more, and a part of the ferromagnetic portion is heat-melted to form a nonmagnetic portion. Formula 1 Formula of Angel Md30 = 413 ─462 (C% + N%) ─9.2 (Si%) ─8.1 (Mn%) ─13.7 (Cr%) ─9.5 (Ni%) ─18.5 (Mo%) = 20 to 90 ° C. Formula 2 Hirayama's equivalent Heq = (Ni%) + 1.05 (Mn%) + 0.65 (Cr%) + 0.36 (Si%) + 12.6 (C%) = 19-23%