JP2000239808A - Corrosion resistant soft magnetic material excellent in antibacterial characteristic - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a corrosion resistant soft magnetic material for members of apparatus requiring antibacterial characteristic, such as solenoid valves for use in the industries connected with food, drinking water, medical treatment, bathes, toilets, or the like. SOLUTION: This material has a composition consisting of by weight <=0.02% C, <=2.5% Si, <=0.50% Mn, <=0.04% P, <=0.10% S, <=0.50% Ni, 4-20% Cr, <=2.5% Mo, 0.1-4.0% Cu, 0.1-4.0% Al, <=1.0% Ti, <=0.02% N, and the balance Fe and satisfying the condition of Ci+12×log(Cu+1)<=22. The material is subjected to working such as hot rolling, cold rolling or drawing, and then held at 700-1050 deg.C for >=10 min, and second phases composed essentially of Cu in the vicinity of the surface of the stock are precipitated in an amount of >=0.15 vol.% in its matrix. Moreover, one or >=2 elements among Pb, Bi, Se, Te, and Ca are further added in weight percentage.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a corrosion-resistant soft magnetic material having excellent antibacterial properties.

[0002]

2. Description of the Related Art In recent years, there has been a need for antibacterial properties for materials used for food, drinking water, medical care, water used in bathrooms, toilets, and the like, especially for improving the sanitary environment and preventing odors. Demand is increasing. On the other hand, as a method of imparting antibacterial properties to a material such as stainless steel used as the above member, there are methods such as antibacterial coating or antibacterial material or composite plating including an antibacterial layer. Due to the possibility of peeling or the like, the reliability is low. In this method, it is necessary to perform processing after processing the parts. Recently, a method of depositing a Cu-rich phase by adding Cu has been proposed.

For example, as disclosed in JP-A-9-170053, C: 0.1% or less, Si: 2% or less, M:
n: 2% or less, Cr: 10 to 30%, and Cu: 0.4 to
3%, the Cu-rich phase is precipitated in the matrix at a rate of 0.2% by volume or more, and can further contain 0.02 to 1% of Nb and / or Ti.
Al: 1% or less, Zr: 1% or less, V: 1% or less, B:
0.05% or less, rare earth metal element (REM): 0.05
% Or less may be added. It is known that the Cu-rich phase is a ferritic stainless steel having a persistent antibacterial property, which is precipitated by 0.2% or more by aging treatment at 500 to 800 ° C after final annealing.

[0004] On the other hand, Japanese Patent Application Laid-Open No. Hei 7-233452 discloses that C: 0.015% or less and N: 0.015% by weight.
% Or less, but C + N: 0.02% or less, Cr: 10 to 10%
14%, Si: 2.0% or less, Mn: 2.0% or less,
P: 0.04% or less, Al: 0.10% or less, Ti:
0.05 to 0.20%, provided that the weight ratio of Ti / (C +
N) ≧ 5.0, S: 0.020% or less, and 0.5 ×
C to 4.0 × C, Cu: 0 to 0.5%, V: 0 to 0.5
%, Ni: 0 to 0.5%, Mo: 0 to 1.0%, balance Fe
Further, ferritic stainless steels having excellent magnetic properties composed of unavoidable impurities are known.

[0005]

SUMMARY OF THE INVENTION The above-mentioned Japanese Patent Application Laid-Open No. 9-1 is disclosed.
No. 70053 is a ferritic stainless steel of Cr: 10 to 30%, and after a final annealing of a Cu-rich phase, 500%.
It precipitates by aging treatment at ~ 800 ° C and separates into two phases. Although it describes antibacterial properties, it does not describe any relationship regarding magnetic properties. On the other hand,
JP-A-233452 describes that Cu is added in an amount of 0 to 0.5% in order to additionally increase corrosion resistance, but there is no description about antibacterial properties. As described above, the present invention is not limited to general stainless steel, and there is no actual application to electromagnetic steel.

[0006]

Means for Solving the Problems In order to solve the above-mentioned problems, the present inventors have intensively developed and as a result, by adding Cu, a Cu-rich phase is precipitated in a matrix, thereby improving antibacterial properties. An object of the present invention is to provide a corrosion-resistant soft magnetic material having both the antibacterial property and the magnetic property of the material itself. The gist of the invention is as follows: (1) By weight%, C ≦ 0.02%, Si ≦ 2.5%, M
n ≦ 0.50%, P ≦ 0.04%, S ≦ 0.10%, N
i ≦ 0.50%, Cr: 4 to 20%, Mo ≦ 2.5%,
Cu: 0.1 to 4.0%, Al: 0.1 to 4.0%, T
i ≦ 1.0%, N ≦ 0.02%, and Cr + 12 × l
heat treatment that satisfies the condition of og (Cu + 1) ≦ 22, is composed of the balance of Fe and inevitable impurities, and is maintained at a temperature in the range of 700 to 1050 ° C. for at least 10 minutes after processing such as hot rolling or cold rolling or drawing. A corrosion-resistant soft magnetic material having excellent antibacterial properties, characterized in that a second phase mainly composed of Cu near the surface of the material is precipitated in the matrix in an amount of 0.15% by volume or more.

(2) C ≦ 0.015% by weight, Si
≦ 2.5%, Mn ≦ 0.30%, P ≦ 0.03%, S ≦
0.02%, Ni ≦ 0.30%, Cr: 4 to 20%, M
o ≦ 2.5%, Cu: 0.5-1.5%, Al: 0.1
２．０2.0%, Ti ≦ 1.0%, N ≦ 0.015%, and the conditions of Cr + 12 × log (Cu + 1) ≦ 22 are satisfied, the balance being Fe and unavoidable impurities, and hot rolling or cold rolling. After processing such as drawing, heat treatment is performed to maintain the temperature in the range of 700 to 1050 ° C. for at least 10 minutes, and the second phase mainly composed of Cu near the material surface precipitates in the matrix in an amount of 0.15% by volume or more. Corrosion-resistant soft magnetic material with excellent antibacterial properties. (3) Pb: 0.03 to 0.40% by weight, Bi:
0.03 to 0.40%, Se: 0.03 to 0.40%,
Te: 0.01 to 0.20%, Ca: 0.002 to 0.
The corrosion-resistant soft magnetic material having excellent antibacterial properties according to claim 1 or 2, further comprising one or more of 050%.

[0008]

The reasons for limiting the components of the present invention will be described below. C ≦ 0.02% C is an element that increases the strength, but is an element that significantly deteriorates magnetic properties and workability, so that it is desirable to reduce it as much as possible. Therefore, the upper limit was restricted to 0.02%. Preferably it is 0.015% or less. Si ≦ 2.5% Si is a basic element involved in the deoxidation of steel, and is effective in improving magnetic properties and corrosion resistance. However, an excessive addition deteriorates the workability, so the upper limit was made 2.5%.

Mn ≦ 0.50% Mn is added as a deoxidizing agent, but excessive addition deteriorates magnetic properties and workability.
Preferably, it is set to 0.30% or less. P ≦ 0.04% P is an element harmful to corrosion resistance and degrades magnetic properties and workability. Therefore, P is set to 0.04% or less, preferably 0.03% or less.

S ≦ 0.10% S is useful for improving the machinability, but degrades corrosion resistance and magnetic properties. Therefore, S is 0.10% or less, preferably 0.00% or less.
2% or less. Ni ≦ 0.50% Ni is an element necessary for improving the corrosion resistance. However, excessive addition deteriorates the magnetic characteristics.
%, Preferably 0.30% or less.

Cr: 4 to 20% Cr is a main element responsible for corrosion resistance, and requires a content of 4% or more. On the other hand, from the viewpoint of workability, a smaller amount is preferable, and for this reason, the content is limited to 20% or less. Mo ≦ 2.5% Mo is a main element responsible for corrosion resistance. However, since excessive addition deteriorates magnetic properties and workability, it is set to 2.5% or less.

Cu: 0.1-4.0% Cu is the most important element of the present invention, and must be 0.1% or more in order to impart good antibacterial properties and acid resistance. However, magnetic properties and workability are deteriorated by excessive addition, so that the content is set to 4.0% or less. Preferably, 0.
5 to 1.5%. Al: 0.1 to 4.0% Al is an element that improves magnetic properties and corrosion resistance. However, the effect is reduced and the workability is deteriorated by excessive addition, so the upper limit is set to 4.0%. Preferably, it is 0.1 to 2.0%.

Ti ≦ 1.0% Ti is an element which exhibits an effect of improving toughness and fixing C and N, and aims at grain refinement. Deteriorates the performance,
The upper limit was set to 1.0%. N ≦ 0.02% Since N is an element that significantly deteriorates magnetic properties and workability, it is desirable to reduce N as much as possible. In the present invention, the upper limit is set to 0.02%. Preferably, it is 0.015%.

Cr + 12 × log (Cu + 1) ≦ 22 The relationship between the amount of Cr and the amount of Cu is regulated based on the relationship between deterioration of hot workability and cold workability and deterioration of magnetic properties. FIG. 1 is a diagram showing the relationship between the amount of Cu and the amount of Cr, and shows that the antibacterial properties are excellent in the ranges of Cu: 0.1 to 4% and Cr: 5 to 20%. P
b: 0.03 to 0.40%, Bi: 0.03 to 0.40
%, Se: 0.03 to 0.40%, Te: 0.01 to
0.20%, Ca: 0.002 to 0.050% One or more of Pb, Bi, Se, Te, and Ca are all added to improve machinability, and excessive addition is effective. Because there are no more, each upper limit was set.

After processing such as hot rolling or cold rolling and drawing, 7
By performing heat treatment at a temperature in the range of 00 to 1050 ° C. for at least 10 minutes or more, the second phase mainly composed of Cu in the vicinity of the material surface is precipitated in the matrix by 0.15% by volume or more, and the antibacterial property is reduced. It is something to have on itself.

[0016]

EXAMPLES After being melted and hot-rolled into steel having the composition shown in Table 1, a final annealing treatment was carried out in a temperature range of 800 to 1000 ° C. for 10 minutes or more. Hc (coercive force) at that time
After processing into a ring test piece, after performing strain relief annealing at a temperature in the range of 850 to 1000 ° C., winding was performed, and DC B-
Obtained from BH loop measured by H tracer. Cu
% Of the second phase (Cu-rich phase) mainly composed of a material obtained by observing the cross-sectional structure near the surface of the material after final annealing. As for antibacterial properties, Staphylococcus aureus (IFO127)
32) is used as a bacterial solution obtained by diluting a culture solution obtained by shaking culture at 35 ° C. for 16 hours with a general ordinary broth medium at a temperature of 16 ° C. with a buffer solution.
1 drop, measure the viable count after storage at 25 ° C for 24 hours,
Those that were killed by 90% or more were rated as ○, those that killed 60 to 90% were rated as Δ, and those that were 60% or less were rated X. As shown in Table 1, Nos. 1 to 19 are steels of the present invention, and Nos. 20 to 26.
Is a comparative steel. Inventive steels Nos. 1 to 19 all have low coercive force, have good magnetic properties, and are excellent in antibacterial properties. On the other hand, it turns out that the comparative steels of Nos. 20 to 26 are particularly inferior in antibacterial properties.

[0017]

[Table 1]

[0018]

As described above, according to the present invention, the antibacterial device such as a solenoid valve used for food, drinking water, medical service, bath of a house, toilet and the like around water is required. It is possible to provide an extremely excellent steel material that can be used as a member.

[Brief description of the drawings]

FIG. 1 is a diagram showing a relationship between a Cu amount and a Cr amount.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C22C 38/60 C22C 38/60

Claims (3)

[Claims] 1. wt%, C ≦ 0.02%, Si ≦ 2.5%, Mn ≦ 0.50%, P ≦ 0.04%, S ≦ 0.10%, Ni ≦ 0.50% , Cr: 4 to 20%, Mo ≦ 2.5%, Cu: 0.1 to 4.0%, Al: 0.1 to 4.0%, Ti ≦ 1.0%, N ≦ 0.02% And the condition of Cr + 12 × log (Cu + 1) ≦ 22 is satisfied, the balance is made of Fe and unavoidable impurities, and after processing such as hot rolling or cold rolling or drawing, 700 to 1050 ° C.
The antibacterial property is characterized in that a heat treatment for maintaining the temperature within the range of at least 10 minutes or more is performed, and the Cu-based second phase near the material surface is precipitated in the matrix in an amount of 0.15% by volume or more. Corrosion resistant soft magnetic material. 2. In% by weight, C ≦ 0.015%, Si ≦ 2.5%, Mn ≦ 0.30%, P ≦ 0.03%, S ≦ 0.02%, Ni ≦ 0.30% , Cr: 4 to 20%, Mo ≦ 2.5%, Cu: 0.5 to 1.5%, Al: 0.1 to 2.0%, Ti ≦ 1.0%, N ≦ 0.015% And the condition of Cr + 12 × log (Cu + 1) ≦ 22 is satisfied, the balance is made of Fe and unavoidable impurities, and after processing such as hot rolling or cold rolling or drawing, 700 to 1050 ° C.
The antibacterial property is characterized in that a heat treatment for maintaining the temperature within the range of at least 10 minutes or more is performed, and the Cu-based second phase near the material surface is precipitated in the matrix in an amount of 0.15% by volume or more. Corrosion resistant soft magnetic material. 3. Pb: 0.03-0.40%, Bi: 0.03-0.40%, Se: 0.03-0.40%, Te: 0.01-0. The corrosion-resistant soft magnetic material having excellent antibacterial properties according to claim 1 or 2, further comprising one or more of 20% Ca: 0.002 to 0.050%.