JP2001011584A - Stainless steel excellent in antibacterial property and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To produce BA finished stainless steel excellent in antibacterial properties and corrosion resistance, and to provide a method for producing the same. SOLUTION: Stainless steel is subjected to BA(bright annealing) treatment and is dipped into a soln. contg. Ag ions of 0.0001 to 1.0 mol/l concn., and the BA film is incorporated with Ag grains and an Ag compd. of 0.0002 to 0.05% by area ratio. The stainless steel preferably contains 0.001 to 0.10 mass % Ag or contains 0.001 to 0.30 mass % V as well.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a stainless steel material, and more particularly to a bright annealed (BA) finish stainless steel having excellent antibacterial properties and having excellent antibacterial properties suitable for use in daily life-related articles, medical equipment and building materials. Steel related. The stainless steel material in the present invention includes a steel plate, a steel strip, a steel pipe, a steel wire, and a stainless steel product finished with BA.

[0002]

2. Description of the Related Art Silver and copper have long been known to have an action of suppressing the growth of pathogenic bacteria represented by Escherichia coli and Salmonella. Recently, materials having an effect of inhibiting bacterial growth (hereinafter referred to as antibacterial properties) using these metals have been developed. For example, Japanese Patent Application Laid-Open No. 8-49085 discloses an antibacterial property in which a metal layer or an alloy layer of Cr, Ti, Ni, Fe or the like containing Ag and / or Cu is formed on the surface of a stainless steel substrate by magnet sputtering. An excellent stainless steel sheet is disclosed. In this steel sheet, it is preferable to form an alloy layer or a metal layer containing 19 to 60% by weight of Ag.

Further, Japanese Patent Application Laid-Open No. 8-156175 proposes a coated steel sheet which can suppress the propagation of bacteria by applying a pigment containing silver. However, in the above-described method of forming an alloy layer or a metal layer containing an antibacterial metal on the surface of a steel sheet, or a method of applying a pigment containing an antibacterial metal, a layer containing the antibacterial metal is formed by drawing or polishing the surface. Is removed or removed, and the effect cannot be expected. Further, in applications such as kitchen supplies, there is also a problem that the antibacterial property cannot be maintained for a long time because the surface is rubbed by cleaning.

[0004] JP-A-8-239726 discloses that the weight ratio is
Iron: 10 to 80%, Aluminum: 1 to 10%, or further contains 1 to 15% of any one or more of chromium, nickel, manganese, and silver, with the balance being copper and unavoidable impurities, antibacterial and sea resistant A living material is disclosed. However, this material is a copper-based alloy or an iron-based alloy containing 1 to 10% of aluminum and has low workability, and is particularly problematic for use in forming thin plates such as tableware, kitchenware, and electric parts. Was leaving.

To cope with such a problem, Japanese Unexamined Patent Publication No. Hei 8-104953 discloses an austenitic stainless steel containing 1.1 to 3.5% by weight of Cu and having an improved antibacterial property.
No. 457 discloses that Cu is 0.5 to 4.0% by weight and Ag is 0.05 to 1.0% by weight.
The austenitic stainless steel containing anti-bacterial property by weight percent contains Cu.
-5.0% by weight of martensitic stainless steel having improved antibacterial properties, and JP-A-9-170053 discloses that
Ferritic stainless steel containing 0.4 to 3.0% by weight and having improved antibacterial properties has been proposed.

However, in order to exhibit antibacterial properties, it is necessary for Cu to be dissolved as ions from the surface of the steel sheet. The dissolution of Cu as ions means that the passive film is destroyed at that location, and even if the antibacterial property is improved, the corrosion resistance is significantly deteriorated. Therefore, it was difficult to achieve both antibacterial properties and corrosion resistance in stainless steel containing a large amount of Cu.

[0007] Japanese Patent Application Laid-Open No. Hei 10-259456 discloses a composition containing 8% by weight or more of Cr and 0.05 to 1.0% by weight of Ag and having a minor axis of 10%.
An antibacterial stainless steel sheet in which an Ag phase of μm or less is dispersed in a matrix in an area fraction of 0.03% or more has been proposed.
However, in the technique described in JP-A-10-259456, it is practically difficult to control the minor axis of the Ag phase to 10 μm or less, and the area ratio of the Ag phase having the minor axis of 10 μm or less is 0.03% or less.
In order to achieve the above, a large amount of Ag must be added, and as a result, there is a problem that workability, corrosion resistance, and surface properties are reduced.

[0008]

Generally, a stainless steel material is made into a final product through a descaling step by pickling, but in the case of a BA-finished stainless steel material, it is annealed in a reducing atmosphere after cold rolling. After (bright annealing treatment (BA treatment)), the product is obtained as it is without a descaling step by pickling.

During this BA treatment (reduction annealing), an oxide film called a BA film having a thickness of about 0.001 to 0.1 μm is formed on the surface of the stainless steel material. Cu existing on the surface of steel
Antibacterial elements such as Ag do not migrate into the BA film only by BA treatment, and when the steel surface is covered with this BA film, the antibacterial elements cannot be dissolved as ions and cannot be dissolved in the surface layer. Antibacterial properties may be significantly reduced.
Further, since the annealing temperature is high in the BA treatment, the antibacterial element disappears from the surface layer, and a region having a low antibacterial element concentration may be formed in the surface layer, and the antibacterial property of the surface layer portion is reduced. There was a problem.

The present invention advantageously solves the above-mentioned problems of the prior art, and has a relatively small Ag content and an enhanced antibacterial property of the surface layer of the final product, and is excellent in antibacterial properties and corrosion resistance, and its production. The aim is to provide a method.

[0011]

Means for Solving the Problems The inventors of the present invention have made intensive studies to achieve both antibacterial properties and corrosion resistance in stainless steel materials. As a result, in the stainless steel BA coating
It has been found that by containing Ag or an Ag compound within an appropriate range, the antibacterial property of the BA-finished stainless steel material can be significantly improved without deteriorating the corrosion resistance. Further, they have found that the antibacterial property of the BA-finished stainless steel material can be remarkably improved by adding a small amount of Ag to the stainless steel material.

The present invention has been completed based on the above findings. That is, the present invention provides a stainless steel which has been subjected to bright annealing treatment (BA treatment) and contains Cr: 8 mass% or more, and preferably contains 0.001 to 0.10 mass% of Ag, or 0.001 to 0.30 mass% of V. Ag particles and Ag compounds (Ag oxide, Ag sulfide, etc.) are contained in an oxide film (BA film) formed on the surface of the stainless steel material by the bright annealing treatment (BA treatment). Bright annealed stainless steel with excellent antimicrobial properties characterized by containing 0.0002 to 0.05% in area ratio.

Further, the present invention provides a stainless steel material that has been subjected to bright annealing treatment (BA treatment),
/ l, preferably 0.001 to 0.10 mol / l, in a solution containing Ag ions at a concentration of 0.001 to 0.10 mol / l, and into the oxide film (BA film) formed on the stainless steel surface by the bright annealing treatment (BA treatment). , Ag particles and Ag compounds at an area ratio of 0.
A method of producing a bright annealed stainless steel material having excellent antibacterial properties, characterized by containing 0002 to 0.05%. In the present invention, the stainless steel material is Ag: 0.00
1 to 0.10 mass%, or V: 0.001 to 0.30 mass
%, And in the present invention, the solution is preferably an aqueous solution, and in the present invention, the aqueous solution is preferably an acidic aqueous solution or an alkaline aqueous solution. In the present invention, the acidic aqueous solution is preferably a nitric acid aqueous solution having a concentration of 0.1 to 60 mass%, and in the present invention, the alkaline aqueous solution is preferably an alkaline aqueous solution having a pH of 8.0 or more.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION As the BA-finished stainless steel material of the present invention, ferrite stainless steel, austenitic stainless steel, and martensitic stainless steel with a Cr content of 8 mass% or more are all suitable.
The chemical composition of ferritic stainless steel is mass%
C: 0.0001 to 0.1%, Si: 1.0% or less, Mn: 2.0% or less, P: 0.1% or less, S: 0.10% or less, Cr: 8 to 50%,
It is preferable to contain N: 0.1% or less, with the balance being Fe and unavoidable impurities. In mass%, Al: 0.3% or less,
Ni: 1.0% or less, Mo: 5.0% or less, Ti: 1.0% or less, N
b: 1.0% or less, Zr: 1.0% or less, Cu: 1.0% or less,
One or more of W: 0.3% or less, Co: 0.001 to 0.5%, and B: 0.01% or less may be contained.

The chemical composition of the austenitic stainless steel is mass%, C: 0.001 to 0.1%, Si: 2.0% or less,
Mn: 2.0% or less, P: 0.1% or less, S: 0.1% or less, C
r: 10 to 35%, Ni: 6 to 15%, N: 0.001 to 0.1%, it is preferable to make the balance Fe and inevitable impurities.
In mass%, Al: 0.3% or less, Mo: 3.0% or less, T:
i: 1.0% or less, Nb: 1.0% or less, Zr: 1.0% or less, C
u: 1.0% or less, W: 0.3% or less, Co: 0.001 to 0.5
%, B: One or more of 0.01% or less may be contained.

The chemical composition of martensitic stainless steel is mass%, C: 0.001 to 1.0%, Si: 1.0% or less,
Mn: 2.0% or less, P: 0.1% or less, S: 0.1% or less, C
It is preferable that r: 8 to 19% and N: 0.001 to 0.1% be contained, with the balance being Fe and unavoidable impurities. In addition, mass%
Al: 1.5% or less, Ni: 3.0% or less, Mo: 3.0% or less, Ti: 1.0% or less, Nb: 1.0% or less, Zr: 1.0% or less, Cu: 1.0% or less, W: 0.3% or less, Co: 0.001 to 0.5
%, B: One or more of 0.01% or less may be contained.

The steel material of the present invention is a stainless steel material which has been subjected to a BA treatment and preferably has a chemical component in the above-mentioned range, and contains Ag particles and an Ag compound in a BA film formed on the surface by the BA treatment. It is a BA-finished stainless steel material containing 0.0002 to 0.05% in area ratio. Further, the BA-finished stainless steel material of the present invention is preferably a stainless steel material having a chemical component in the above range and further containing 0.001 to 0.10 mass% of Ag, or 0.001 to 0.30 mass% of V.

First, the reasons for limiting the contents of Ag and V in the composition of the stainless steel material of the present invention will be described.
In addition, in this invention, it is preferable that components other than Ag and V fall within the range of the above-mentioned generally known various stainless steels. Ag: 0.001 to 0.10 mass% The antibacterial carrier in the present invention is a trace amount of Ag contained in the stainless steel material. In order to express stable antibacterial properties, in the present invention, Ag is uniformly distributed in the steel material,
In addition, the presence form is controlled so as to elute at an appropriate rate. That is, the point is to control the Ag content and the form of existence for the expression of antibacterial properties, the addition of a special element for uniform distribution of Ag, and the control of manufacturing conditions.

Ag is the most important element in the present invention, and has the effect of suppressing the growth of bacteria and enhances the antibacterial properties. These effects are recognized when added at 0.001 mass% or more, but when added over 0.10 mass%, they have the effect of increasing antibacterial properties. However, corrosion resistance deteriorates, surface defects during hot rolling increase, and the cost increases. Since a large amount of Ag is added in a large amount, the cost is increased, which is economically disadvantageous. For these reasons, the amount of Ag contained in the steel is limited to the range of 0.001 to 0.10 mass%. In addition, more preferably 0.01 to 0.05 mass
%.

The Ag contained in the steel material exists in the form of Ag particles, Ag oxides and Ag sulfides. According to the knowledge of the present inventors, the antibacterial effect is expressed as Ag oxide> Ag particles> Ag sulfide is superior in order, and it is preferable that Ag is present together with Ag particles or further Ag oxide from the viewpoint of improving antibacterial properties. V: 0.001 to 0.30 mass% V is 0.001 to 0.30 ma in addition to the above range of Ag.
It is preferable to contain ss%. V represents Ag particles and Ag
It significantly improves the tendency of Ag compounds such as oxides and Ag sulfides to be unevenly distributed in the center of the plate thickness, has the effect of uniformly dispersing Ag particles and Ag compounds in steel, and is effective in improving the antibacterial properties of steel. Element. By containing V at 0.001 mass% or more,
Antimicrobial properties of a homogeneous steel surface are achieved. On the other hand, 0.30mass
%, The workability of the steel material tends to decrease. For this reason, V is preferably in the range of 0.001 to 0.30 mass%. More preferably, it is 0.001 to 0.10 mass%, and still more preferably, 0.010 to 0.025 mass%.

The stainless steel material of the present invention having the above composition is subjected to a BA treatment to form a BA film on the surface.
In the present invention, the BA film contains the Ag particles and the Ag compound in an area ratio of 0.0002 to 0.05%. When the surface of the steel material is covered with the BA film by the BA treatment, the antibacterial property of the surface of the steel tends to decrease inside the steel material. Therefore, in the present invention, Ag particles and an Ag compound are contained in the BA film on the surface. When the content of the Ag particles and the Ag compound in the BA film is less than 0.0002% in area ratio, the expression of antibacterial properties is smaller than in the steel material. On the other hand, when the content of the Ag particles and the Ag compound exceeds 0.05% in area ratio, the BA film has many defects and the corrosion resistance is reduced. For these reasons, the content of the Ag particles and the Ag compound in the BA film was limited to the area ratio of 0.0002 to 0.05%. The area ratio is preferably 0.001 to 0.
03%. More preferably, the area ratio is 0.001 to 0.02%.
It is.

In the present invention, for the steel material after the BA treatment,
Analyze the components from the surface layer in the depth direction (thickness direction) using a field emission Auger electron spectrometer or glow discharge optical emission spectrometer, and the intensity of iron (Fe) and oxygen (O) becomes constant (steady state). The range from the surface up to the point where it becomes is defined as a BA film. In the present invention, the content of the Ag particles and the Ag compound in the BA film was determined by measuring the surface side of the BA film using an electro-emission type Auger electron spectrometer or an electron beam microanalyzer, and determining the area ratio using an image analyzer. Shall be used.

Next, a method for producing the BA-finished stainless steel material of the present invention will be described. The stainless steel material of the present invention can be smelted by applying all commonly known smelting methods, and thus the smelting method does not need to be particularly limited. Preferably, Ag: 0.001 to 0.10 mass%, or further, V: 0.00
Stainless steel molten steel containing 1 to 0.30 mass% is usually produced by a known method. The molten steel produced can be made into a steel material by a generally known casting method, but it is preferable to apply a continuous casting method from the viewpoint of productivity and quality.

In the continuous casting method, the casting speed is set to a value of 0.1 to uniformly distribute the Ag particles or the Ag compound in the steel.
It is desirable to be in the range of 8 to 1.6 m / min. If the casting speed is less than 0.8 m / min, the Ag compound becomes coarse and the corrosion resistance deteriorates. On the other hand, when the casting speed exceeds 1.6 m / min, stable casting is difficult and the distribution of Ag compounds becomes uneven. For this reason, the casting speed in the continuous casting method is set to 0.8 to
It is preferably in the range of 1.6 m / min.

In the present invention, the molten stainless steel having the above-mentioned chemical composition is preferably cast continuously under the above-mentioned conditions to obtain a steel material, and then, if necessary, the steel material is heated to a predetermined temperature. Then, a desired hot rolled sheet (steel strip or steel sheet after hot rolling) is formed by hot rolling. The hot rolled sheet is optionally annealed, preferably at a temperature of 700-1200 ° C,
Further, after being subjected to pickling, it is subjected to cold rolling to obtain a cold-rolled sheet having a predetermined thickness (a steel strip or a steel sheet after cold rolling).

The cold-rolled sheet is then subjected to 700-700 in a reducing atmosphere.
It is preferable to apply a bright annealing (BA) treatment at 1200 ° C. to obtain a BA-finished steel material. By the BA treatment, a BA film is formed on the steel material surface. The BA-finished steel having the BA coating is subjected to a BA treatment or processed into a product, and then immersed in a solution having an Ag ion concentration of 0.0001 to 1.0 mol / l.

By immersing the steel material in a solution containing Ag ions, the Ag ions in the solution are converted into thin portions of the BA film,
Alternatively, it is deposited on a defective portion of the BA film and greatly improves the antibacterial property of the surface layer. Such an improvement in antibacterial properties
It is expressed at an Ag ion concentration of 0.0001 mol / l or more and 1.0 mol / l
It shows a tendency to saturate at a degree. Ag ion concentration of 1.0 mol / l
Exceeding the range requires a large amount of an Ag ion-forming agent (eg, Ag particles) to be added to the solution, resulting in an increase in cost. Therefore, it is preferable that the Ag ion concentration in the solution be in the range of 0.0001 to 1.0 mol / l. Incidentally, more preferably 0.001 to 0.10
mol / l.

The Ag ion forming agent added to contain Ag ions in the solution is not particularly limited, and examples thereof include Ag particles, Ag ₂ O particles, and an aqueous silver nitrate solution. The type of solution containing Ag ions, which is used to immerse steel with a BA coating,
Both aqueous solutions (eg, neutral industrial water, acidic aqueous solutions, alkaline aqueous solutions) and organic solvents (eg, acetone) are suitable. By immersing the steel material having the BA film in the solution containing these Ag ions, the antibacterial property can be enhanced. The solution is preferably an aqueous solution, and the aqueous solution is preferably an acidic aqueous solution or an alkaline aqueous solution.

When an acidic aqueous solution or an alkaline aqueous solution is used, adhesion of Ag ions to the BA film is promoted. The reason for this has not been clarified at present, but it is presumed that the precipitate in the BA film soluble in acid or alkali elutes into the solution, and Ag ions adhere to the eluted portion. For this reason, when a steel material having a BA film is immersed in an acidic aqueous solution or an alkaline aqueous solution, the antibacterial property and the corrosion resistance are further improved.

As the acidic aqueous solution, an aqueous nitric acid solution, preferably an aqueous nitric acid solution having a concentration of 0.1 to 60 mass% is preferable. If the nitric acid concentration is less than 0.1 mass%, the improvement in antibacterial properties is small,
On the other hand, if it exceeds 60 mass%, the surface gloss of the steel material deteriorates. Therefore, the concentration of the aqueous nitric acid solution is preferably set to 0.1 to 60 mass%. More preferably, it is 1 to 20 mass%.
More preferably, it is 7 to 13 mass%.

As the alkaline aqueous solution, an alkaline aqueous solution having a pH of 8.0 or more is preferable. More preferably, pH 9.0
Above, more preferably pH 10 or more. In the case of the alkaline aqueous solution, in addition to the improvement of the antibacterial property, there is also a surface cleaning effect. If the pH is less than 8.0, the adhesion of Ag ions is small and the improvement of antibacterial properties is small. In addition, a NaOH aqueous solution is illustrated as an alkaline aqueous solution.

The immersion time of the BA finished steel in the solution is preferably 0.1 sec or more. 0.1s immersion time
If it is less than ec, the adhesion of Ag ions to the BA film is insufficient, and no improvement in antibacterial properties can be obtained. On the other hand, immersion for more than 20 seconds may cause disadvantages such as a decrease in productivity and a deterioration in surface gloss. The preferred immersion time is 2 seconds or more.

In the present invention, a method of enhancing the antibacterial property of the surface layer of a BA-finished stainless steel material has been described. However, the method of the present invention is also suitable for a surface-finished stainless steel sheet other than the BA finish. When the antibacterial property of the surface layer of the surface-finished stainless steel sheet other than the BA finish is deteriorated for some reason, the antibacterial property is restored by immersing in the solution containing the Ag ion of the present invention.

[0034]

EXAMPLES (Example 1) A stainless steel having the chemical composition shown in Table 1 was melted and made into a slab by a continuous casting method in which the casting speed was changed. These slabs were heated to form a hot-rolled sheet having a thickness of 4.0 mm by hot rolling. Next, these hot-rolled sheets were annealed at 700 to 1200 ° C., pickled, and then cold-rolled into cold-rolled sheets having a thickness of 0.8 mm.

These cold-rolled sheets were subjected to a BA treatment in a reducing atmosphere to obtain a BA-finished steel strip. In addition, BA processing is H ₂
The test was carried out in a reducing atmosphere consisting of a H ₂ —N ₂ mixed gas (dew point: −30 to −60 ° C.) at a partial pressure of 0.75 atm (0.76 MPa). After the BA treatment, these steel strips were immersed in a solution containing Ag ions at the concentrations shown in Table 2 for the immersion time shown in Table 2. The annealing temperature of the cold rolled sheet is 800 to 800 for ferritic stainless steel.
1050 ℃, 900 ~ 1200 for austenitic stainless steel
C., 780 to 850 C. for martensitic stainless steel.

Test specimens were collected from these BA-finished stainless steel sheets and subjected to an antibacterial test and a corrosion resistance test. Further, in order to confirm the durability and durability of the antibacterial property, an antibacterial property test was performed after immersion in boiling water at 100 ° C for 24 hours. The content of Ag and Ag compound in the BA film is
The area ratio was measured by an image analyzer using an electron beam micro analyzer.

The outline of the test method for each test is described below.
You. (1) Antibacterial test Antibacterial properties conform to the film adhesion method of the Antibacterial Products Technology Council
And evaluated. Specimen (50mm x 50mm) is made of absorbent cotton containing 99.5% ethanol
Wash and degrease with etc. E. coli is dispersed in a 1/500 NB solution. (The number of bacteria is
2.0 × 10^Five~ 1.0 × 10 ⁶Adjusted to cfu / ml. 1/500 N
The B solution is a 50% normal Bion medium (NB)
It is a dilution of 1: 0. Normal Bion medium (NB)
Means meat extract 5.0g, sodium chloride 5.0g, peptone 1
0.0g, purified water 1.000ml, pH: 7.0 ± 0.2
U. 0.4 ml / 25cm of bacterial solution^TwoOf test pieces (3 each)
To seed.

A polyethylene film is put on the surface of the test piece. Store at a temperature of 35 ° C ± 1.0 ° C and RH 90% or more for 24 hours. (RH is relative humidity.) The number of viable bacteria is measured by agar culture method (35 ± 1.0 ° C, 40-48 hours)
Was performed. The antibacterial activity was evaluated by a sterilization rate defined by the following equation.

Bacterial reduction rate (%) = (number of bacteria in control−number of bacteria after test) / (number of bacteria in control) × 100 It refers to the viable count. The number of bacteria after the test is the number of viable bacteria measured. (2) Corrosion resistance test The corrosion resistance was evaluated by a salt-dry / wet combined cycle test.

A test piece (50 mm × 50 mm) was sprayed with a 5.0% aqueous NaCl solution (temperature: 35 ° C.) for 0.5 hours, and then dried in a dry atmosphere at a humidity of 40% or less and a temperature of 60 ° C. for 1.0 hour.
Hold for hours. Humidity: 95% or more, temperature: Keep in a humid atmosphere of 40 ° C for 1.0 hour. Are combined into one cycle, and a plurality of cycles (5 to 30 cycles) set for each of the two test pieces for each steel type are repeated, and then the rusting area ratio (% ) Was measured. The number of repetition cycles was 10 for ferritic stainless steel, 30 for austenitic stainless steel, and 5 for martensitic stainless steel.

Table 2 shows the results.

[0042]

[Table 1]

[0043]

[Table 2]

[0044]

[Table 3]

[0045]

[Table 4]

The examples of the present invention exhibit excellent antibacterial properties both as products and after immersion in boiling water at 100 ° C. for 24 hours.
Further, it can be seen that excellent antibacterial activity is maintained even after polishing the product to 2 μm. Further, the examples of the present invention have a low rusting area ratio and are excellent in corrosion resistance. The above results can be confirmed regardless of the type of stainless steel. On the other hand, the comparative examples outside the scope of the present invention have deteriorated antibacterial properties or deteriorated corrosion resistance. Steel materials No. 16, No. 29, No. 46 whose Ag content in the steel material is outside the preferred lower limit of the present invention.
Has degraded antibacterial properties after polishing. Further, a steel material in which the amount of Ag particles and Ag compounds in the BA film is outside the lower limit of the present invention.
In No. 15, No. 28, No. 38 and No. 47, the antibacterial properties of the products as they are deteriorated, but the antibacterial properties appear after polishing. On the other hand, the steel materials No. 24 and No. 53 in which the amounts of Ag particles and Ag compounds in the BA film are outside the upper limits of the present invention have deteriorated corrosion resistance.

As for the antibacterial properties, a sterilization rate of 99.0% or more was judged to be acceptable. As for corrosion resistance, a sterilization rate of 99.0% or more was satisfied, and a rusting area rate of 15% or less was judged as acceptable. (Example 2) Continuous casting in which a stainless steel having the same composition as the stainless steel having the chemical composition shown in Table 1 (Steel No. 12, No. 22, No. 32) was melted and the casting speed was changed. A slab was obtained by the method. These slabs were heated to form a hot-rolled sheet having a thickness of 4.0 mm by hot rolling. Next, these hot-rolled sheets were annealed at 700 to 1200 ° C., pickled, and then cold-rolled into cold-rolled sheets having a thickness of 0.8 mm.

These cold-rolled sheets were subjected to a BA treatment in a reducing atmosphere to obtain a BA-finished steel strip. In addition, BA processing is H ₂
The test was carried out in a reducing atmosphere consisting of a H ₂ —N ₂ mixed gas (dew point: −30 to −60 ° C.) at a partial pressure of 0.75 atm (0.76 MPa). Using these BA-finished steel strips, the bottom radius is 50mm,
It was pressed into a cylinder having a height of 100 mm. After pressing, these pressed products were immersed in a solution containing Ag ions at the concentrations shown in Table 3 for immersion times shown in Table 3, respectively.

A test piece (50 × 50 mm) was sampled from the center of the bottom surface of these pressed products, and an antibacterial test and a corrosion resistance test were performed. The test methods of the antibacterial test and the corrosion resistance test were the same as in Example 1. Table 3 shows the results.
Shown in

[0050]

[Table 5]

It is recognized that all of the pressed products (steel materials No. 54 to No. 59) of the present invention obtained by pressing the BA-finished steel strip have sufficient antibacterial properties and corrosion resistance. The above results can be confirmed regardless of the type of stainless steel.

[0052]

According to the present invention, any type of ferritic, austenitic or martensitic stainless steel having excellent antibacterial properties and corrosion resistance can be provided.
It has a remarkable industrial effect. In addition, molding and polishing are performed, and materials with an emphasis on hygiene, such as stainless steel materials with excellent antibacterial properties and corrosion resistance applied to uses where bacteria easily proliferate in humid environments such as kitchens and bathtubs. There is also an effect that it can be easily manufactured.

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (Reference) C23C 18/42 C23C 18/42 (72) Inventor Susumu Suto 1 Kawasaki-cho, Chuo-ku, Chiba-shi, Chiba Kawasaki Steel Corporation Inside the Technical Research Institute (72) Inventor Haruhiko Ishizuka 1 Kawasaki-cho, Chuo-ku, Chiba City, Chiba Prefecture Inside Kawasaki Steel Corporation Chiba Works (72) Inventor Masaharu Ikeda 1 Kawasaki-cho, Chuo-ku, Chiba City, Chiba Prefecture Kawasaki Steel Corporation Chiba Works

Claims (9)

[Claims] 1. Cr: 8 mass subjected to bright annealing treatment
% Or more, wherein the oxide film formed on the surface of the stainless steel material by the bright annealing treatment contains Ag particles and an Ag compound in an area ratio of 0.0002 to
Bright annealed stainless steel with excellent antibacterial properties characterized by containing 0.05%. 2. The method according to claim 1, wherein the stainless steel material is Ag: 0.001 to 0.1.
The bright annealed stainless steel material having excellent antibacterial properties according to claim 1, wherein the stainless steel material contains 10 mass% or V: 0.001 to 0.30 mass%. 3. The stainless steel material is subjected to bright annealing treatment, then immersed in a solution containing Ag ions at a concentration of 0.0001 to 1.0 mol / l, and formed on the surface of the stainless steel material by the bright annealing treatment. A method for producing a bright annealed stainless steel material having excellent antibacterial properties, characterized in that the oxide film contains Ag particles and an Ag compound in an area ratio of 0.0002 to 0.05%. 4. The stainless steel material has an Ag content of 0.001 to 0.4.
The method for producing a bright annealed finish stainless steel material having excellent antibacterial properties according to claim 3, wherein the stainless steel material is 10 mass%, or further contains V: 0.001 to 0.30 mass%. 5. The method according to claim 1, wherein the solution containing the Ag ion is 0.001 to 0.1.
5. The method for producing a bright annealed stainless steel material having excellent antibacterial properties according to claim 3, wherein the solution contains Ag ions at a concentration of 10 mol / l. 6. The method for producing a bright annealed stainless steel material having excellent antibacterial properties according to claim 3, wherein the solution containing Ag ions is an aqueous solution. 7. The method according to claim 6, wherein the aqueous solution is an acidic aqueous solution or an alkaline aqueous solution. 8. The acidic aqueous solution has a concentration of 0.1 to 60 mass.
The method for producing a bright annealed finish stainless steel material having excellent antibacterial properties according to claim 7, wherein the aqueous solution is a 0.1% aqueous solution of nitric acid. 9. The method according to claim 7, wherein the alkaline aqueous solution is an alkaline aqueous solution having a pH of 8.0 or more.