KR19990032693A - Ferritic antibacterial stainless steel and its manufacturing method - Google Patents

Abstract

The present invention relates to a ferritic antibacterial stainless steel having anti-bacterial properties and a method for producing the same;

The purpose is to provide a waste-light antibacterial stainless steel and its manufacturing method that can have antimicrobial properties while maintaining the mechanical properties intact in ferritic stainless steel.

The present invention for achieving the above object by weight, C: 0.016%, N: 0.015%, Si: 0.75% or less, Mn: 1.0% or less, P: 0.04% or less, S: 0.03% or less, Cr: 18 A waste-light antibacterial stainless steel that satisfies -22%, Cu: 1.4-2.0%, Nb: 0.4-1.0%, Ag: 0.04-0.2%, and C + N: 0.024% or less and consists of the remaining Fe and other unavoidable impurities. And ferritic antibacterial comprising hot-rolling a steel having the above components in a conventional manner, followed by cold rolling, continuous annealing, and then holding at a temperature of 400-650 ° C. for 0.5-2 hours. The summary relates to a method for producing a stainless steel sheet.

Description

Ferritic antibacterial stainless steel and its manufacturing method

The present invention relates to a ferritic stainless steel and a method for manufacturing the same, and more particularly, ferritic anti-bacterial stainless steel containing Cu, Nb, Ag as elements to secure anti-bacterial properties in ferritic stainless steel and It relates to a manufacturing method.

Anti-bacterial steel refers to a material that prevents and kills proliferation of Escherichia coli and Staphylococcus aureus and prevents diseases such as food poisoning. The antibacterial mechanism comprises Cu ⁺² ions and bacteria eluted from the material. It is known that the S component combined to take the form of CuS slows down the activity of the bacterium and eventually kills it. The antibacterial steel is expected to be used for various purposes such as dish drums or washing machine drums in order to prevent disease, but has not made a clear technological development to date.

Antibacterial stainless steels include NSSAM1 steel, which contains 17% Cr-1.5% Cu, which was developed by Ilshin Steel Co., Ltd., but the technical content cannot be determined because there is no specific disclosure.

On the contrary, a coated steel sheet which gives antimicrobial properties by concentrating Cu and Ag components to about 6-21% and 19-60%, respectively, on the surface of a stainless steel sheet has been presented in Japanese Unexamined Patent Publication No. 8-49085. In addition, antibacterial coated steel sheets coated with silver powder on ordinary carbon steel were presented by Daedong Special Steel and Kawadetsu Co., Ltd., respectively. Although the above-mentioned coated steel sheet has some antibacterial property, there is a limit of product life due to the consumption of the coating layer, and in particular, there is a problem that the antimicrobial properties vary depending on the surface of the product due to unevenness of the plating layer due to processing. Accordingly, the situation is required to develop a material having antimicrobial properties of the steel itself so as to overcome the problem of the coated steel sheet.

Accordingly, the present inventors have studied various angles so that the ferromagnetic body has antimicrobial properties. As a result, the present invention controls the component system so that Cu is easily eluted in ordinary ferritic stainless steel, and heat treatment conditions are performed so that the Cu precipitates are finely precipitated. When controlled, it was confirmed that the antibacterial property could be secured, and the present invention was proposed.

That is, an object of the present invention is to provide a waste-light antibacterial stainless steel that can have antimicrobial properties while maintaining the mechanical properties intact in ferritic stainless steel. Furthermore, to provide a method for producing the antibacterial steel, there is another object.

Antibacterial steel of the present invention for achieving the above object by weight, C: 0.016%, N: 0.015%, Si: 0.75% or less, Mn: 1.0% or less, P: 0.04% or less, S: 0.03% or less, Cr: 18-22%, Cu: 1.4-2.0%, Nb: 0.4-1.0%, Ag: 0.04-0.2% and C + N: 0.024% or less, satisfying the rest of Fe and other unavoidable impurities .

Furthermore, the method for producing the antimicrobial steel sheet of the present invention, in weight%, C: 0.016%, N: 0.015%, Si: 0.75% or less, Mn: 1.0% or less, P: 0.04% or less, S: 0.03% or less, Slabs made of Cr: 18-22%, Cu: 1.4-2.0%, Nb: 0.4-1.0%, Ag: 0.04-0.2% and C + N: 0.024% or less and remaining Fe and other unavoidable impurities are usually used. After hot rolling in the method of, followed by cold rolling and continuous annealing, and then maintained at a temperature of 400-650 ° C for 0.5-2 hours, followed by the furnace cooling.

Hereinafter, the present invention will be described in detail.

The present invention is characterized by the addition of Nb to finen the Cu precipitates to facilitate the elution of Cu to 18% Cr-based ferritic stainless steel, while further improving the antimicrobial properties by adding Ag. That is, the present invention adds Cu, Nb, and Ag to 18% Cr-based ferritic stainless steel, that is, AISI 430 steel, which is used for materials requiring corrosion resistance and workability, and has antimicrobial properties, while workability is equivalent to that of conventional materials. It is to keep over.

Therefore, among the steel components of the present invention, Cu, Nb, and other components except Ag limit the content of the steel grade regulation range of the conventional 430 system, briefly explain the reason as follows.

First, C and N are each added less than 0.15% when cleanliness is required in 430 steel. In addition, the C and N are present as a solid solution as the invasive element having a similar atomic size, and are relatively inexpensive and have a similar role in steel, so that the content of the two elements is controlled by C + N. That is, in order to maintain corrosion resistance and workability, it is necessary to make C + N below 0.024%.

Si and Mn have no significant effect on the antibacterial properties of the present invention. Both components are inevitably introduced from scrap metal in the steelmaking process, and Si is 0.75% or less for cost reduction in the usual 430 grades. Mn is added at 1.0% or less.

P and S are added below 0.04% and S below 0.03% for corrosion resistance and formability, respectively.

Cr is added at 18-22% to ensure sufficient corrosion resistance.

As described above, Cu, Nb, and Ag are appropriately added to the conventional 430 steel to secure antibacterial properties.

First, as the content of Cu increases, the amount of ε-Cu precipitates increases, so that the amount of Cu ⁺² elution increases, but when Cu amount exceeds 2.0%, the workability becomes poor. It is preferable to add in 2.0% of range.

The Nb stabilizes the ε-Cu precipitates as well as the stability of the C + N component, and serves to inhibit the growth of the ε-Cu precipitates at room temperature, the effect is less than 0.3%, if more than 1.0% Since the effect is saturated, it is preferable to make Nb addition amount into 0.4-1.0% of range.

Ag added more than 0.4%, the antibacterial properties are more enhanced, it is estimated that Ag plays a role in promoting Cu ⁺² elution or a small amount of Ag itself to remove the bacterial component S. At this time, considering the Ag component is expensive, it is limited to the range of 0.4-2.0%.

Steel formed as described above is produced a cold rolled sheet by a conventional method for producing 18% Cr steel. That is, the steel is hot rolled by a conventional method, then cold rolled and continuously annealed to obtain a cold rolled sheet.

According to the present invention, when the cold-rolled sheet is aged under appropriate conditions, ε-Cu-type precipitates are precipitated finely, and thus the total surface area of the precipitates is increased, so that the elution of Cu ⁺² ions is promoted and antibacterial properties are achieved. To improve. That is, it is necessary to hold the cold rolled plate at a temperature of 400-650 ° C. for 0.5-2 hours and then to cool the furnace.

The reason for this is that when the aging treatment temperature is lower than 350 ° C, the processability is excellent but the antibacterial property is lowered. When it exceeds 700 ° C, the antibacterial property is excellent but the processability is poor. In addition, when the aging treatment time is less than 2 hours at 400 ℃ or longer than 30 minutes at 650 ℃, either processability and antimicrobial properties are poor.

Hereinafter, the present invention will be described in detail through examples.

Example 1

The hot rolled steel sheet having the components shown in Table 1 was maintained at 870 ° C. for 5 hours, and then cold-rolled at 70% rolling rate to obtain a cold rolled sheet, followed by continuous annealing at 1050 ° C. for 2 minutes, and air cooling. While measuring the sterilization rate of the obtained steel sheet, the limiting drawing ratio (hereinafter referred to as 'LDR') for the evaluation of formability was measured and the results are shown in Table 1 below.

At this time, the sterilization rate was determined by culturing the approved spawn, diluting it, applying an appropriate amount to the surface of the material, and maintaining it for a certain time. Then, the sterilization rate was determined by counting colony numbers by germ growth. Membrane Filtaration was used.

River C Si Mn P S Cr Cu Ag N C + N Sterilization Rate (%) LDR Comparative Steel 1 0.015 0.35 0.71 0.008 0.008 19.3 1.3 ^* 0.007 0.022 5 2.3 Comparative Steel 2 0.016 0.33 0.65 0.008 0.008 19.2 1.4 0.008 0.024 10 2.3 Comparative Steel 3 0.014 0.34 0.73 0.009 0.007 19.3 1.7 0.008 0.022 11 2.3 Comparative Steel 4 0.011 0.35 0.72 0.007 0.008 19.3 2 0.008 0.017 13 2.3 Comparative Steel 5 0.011 0.33 0.68 0.008 0.009 19.2 2.5 ^* 0.006 0.018 15 2.2 Comparative Steel 6 0.014 0.35 0.67 0.008 0.007 19.3 1.5 0.007 0.021 18 2.2 Comparative Steel 7 0.015 0.37 0.74 0.007 0.007 19.4 1.5 0.007 0.022 22 2.2 Comparative Steel 8 0.016 0.35 0.59 0.008 0.006 19.3 1.5 0.007 0.024 23 2.2 Comparative Steel 9 0.015 0.38 0.65 0.008 0.007 19.3 1.5 0.008 0.02 23 2.2 Comparative Steel 10 0.015 0.34 0.73 0.007 0.008 19.3 1.5 0.03 ^* 0.005 0.022 23 2.2 Inventive Steel 1 0.014 0.35 0.74 0.008 0.008 19.4 1.5 0.04 0.007 0.021 25 2.2 Inventive Steel 2 0.016 0.35 0.76 0.009 0.008 19.3 1.5 0.05 0.008 0.024 26 2.2 Invention Steel 3 0.012 0.36 0.74 0.008 0.008 19.3 1.5 0.1 0.008 0.02 30 2.2 Inventive Steel 4 0.013 0.37 0.78 0.008 0.008 19.3 1.5 0.2 0.007 0.02 35 2.2 * Mark is outside the conditions of the present invention

As shown in Table 1, the invention steel (1-4) containing a proper amount of Cu, Nb, Ag in 18% Cr according to the present invention is secured at a level of 25% or more while maintaining the workability at a normal level And it was found.

Example 2

As shown in Table 2, the continuously annealed cold rolled sheet of Example 1 was maintained for 0.5-4 hours at a temperature range of 350-700 ° C., and then aged under conditions of no-cooling, and then the sterilization rate and the LDR value were measured. The results are shown in Table 2 below.

Sample processing condition 350 ℃ × 4hr 400 ℃ × 2hr 500 ℃ × 1hr 650 ℃ × 30min 700 ℃ × 20min Steel grade Sterilization Rate (%) LDR value Sterilization Rate (%) LDR value Sterilization Rate (%) LDR value Sterilization Rate (%) LDR value Sterilization Rate (%) LDR value Comparative Steel 1 15 2.3 65 2.2 68 2.2 70 2.2 77 2 Comparative Steel 2 21 2.3 75 2.2 80 2.2 75 2.2 80 1.8 23 2.2 78 2.2 82 2.2 80 2.2 80 1.8 Comparative Steel 3 Comparative Steel 4 25 2.2 80 2.2 84 2.2 83 2.1 85 1.8 Comparative Steel 5 25 2.2 82 2.1 86 2.2 83 2.1 88 1.7 Inventive Steel 6 28 2.2 85 2.2 89 2.2 87 2.1 88 1.7 Comparative Steel 7 30 2.2 95 2.2 96 2.2 95 2.1 94 1.7 Comparative Steel 8 32 2.2 92 2.2 96 2.1 97 2.1 98 1.6 Comparative Steel 9 32 2.2 93 2.2 97 2.1 97 2.1 98 1.6 Comparative Steel 10 33 2.2 92 2.2 97 2.1 97 2.1 98 1.6 Inventive Steel 1 36 2.2 99 2.2 99 2.1 99 2.1 99 1.5 Inventive Steel 2 36 2.2 99 2.2 99 2.1 99 2.1 99 1.5 40 2.2 99 2.2 99 2.1 99 2.1 99 1.5 Invention Steel 3 Inventive Steel 4 45 2.1 99 2.2 99 2.1 99 2.1 99 1.5

As shown in Table 2, when the aging treatment temperature is 700 ℃, LDR, which is a moldability index much lower than the reference value 2.1, regardless of the steel grade, and also less than 300 ℃ LDR was excellent, but the sterilization rate was not good. And, even if the comparative steel (1-10) heat treatment under the aging treatment conditions presented in the present invention, the sterilization rate was poor.

On the contrary, when the inventive steel (1-4) was heat treated at a temperature of 400-650 ° C. for 0.5-2 hours, the sterilization rate and LDR value were excellent.

As described above, the present invention can provide an antimicrobial steel sheet having excellent antimicrobial properties while maintaining the same level of processability compared to steel grades of the conventional 430 system, the antimicrobial steel sheet provided by the present invention can be applied to a washing machine drum, tableware, etc. That would have a useful effect.

Claims (2)

By weight%, C: 0.016%, N: 0.015%, Si: 0.75% or less, Mn: 1.0% or less, P: 0.04% or less, S: 0.03% or less, Cr: 18-22%, Cu: 1.4-2.0 A waste-light antibacterial stainless steel which satisfies%, Nb: 0.4-1.0%, Ag: 0.04-0.2% and C + N: 0.024% or less, and is composed of the remaining Fe and other unavoidable impurities. In the method of manufacturing a ferritic stainless steel sheet comprising hot-rolling a ferritic stainless steel slab, cold rolling to produce a cold rolled sheet, and then continuous annealing, The ferritic stainless steel slab is in weight%, C: 0.016%, Si: 0.75% or less, Mn: 1.0% or less, N: 0.015%, P: 0.04% or less, S: 0.03% or less, Cr: 18-22 %, Cu: 1.4-2.0%, Nb: 0.4-1.0%, Ag: 0.04-0.2% and C + N: 0.024% or less, consisting of the remaining Fe and other unavoidable impurities, the continuous annealed cold rolled plate Method of producing a ferritic antibacterial stainless steel sheet, characterized in that it comprises a furnace and then maintained at a temperature of 400-650 ℃ 0.5-2 hours.