Art
[1]
The invention also relates to a martensitic stainless steel and a method of manufacturing a high hardness is excellent in anti-microbial.
BACKGROUND
[2]
Recent Users of hygiene in accordance with the standard of living improves, the has increased the interest of safety, is thereby hygiene that can not only inhibit the rust most important characteristic of stainless inhibit bacteria such as E. coli and Staphylococcus aureus strengthen functional development of antibacterial stainless steel, has been desired.
[3]
A method for imparting antimicrobial properties to stainless steel, there is a way to express the antimicrobial by the addition of a metal element such as Ag, Cu in a stainless steel is known as the most common method.
[4]
For Ag Cu compared to denote known, but superior antibacterial properties, the material is so expensive to uniformly within, as well as causing the degradation of corrosion resistance due to the properties of the high capacity of a stainless steel base, a small portion of a relatively large element base dispersion / distribution there are difficult drawbacks.
[5]
For Cu Ag cost compared to a case also the addition of a certain amount or more of Cu to stainless steel in accordance with the indicated excellent properties as the antibacterial substance exhibits excellent antibacterial properties has been reported.
[6]
In summary, the addition of Cu stainless steel utensils antibacterial activity as follows:
[7]
If the amount of Cu added to stainless steel is a Cu element present in the surface layer by a water ionization trace of the steel surface to enable the Cu2 + ion. The active Cu2 + ions to kill bacteria in the end to slow the activity of the E. coli and SH group enzymes necessary for normal reaction of the bacteria, such as Staphylococcus aureus may enhance hygiene.
[8]
On the other hand, the amount of Cu2 + ion that may be eluted in the form of ions through contact with the water through the paid Cu atom is bound to extremely limited since the film is a dense STS passivation on the surface formed when the river.
[9]
In addition to the antibacterial properties disadvantage as not only it can shorten the duration of the antimicrobial activity as well.
[10]
To solve this problem, in recent years by a special heat treatment for a period of time the prepared steel sheet at an appropriate temperature range has been proposed a method of finely precipitate the Cu-rich phase precipitates (e-Cu).
[11]
This is due to the fact that by a special heat treatment and Cu2 + ions eluted is activated from the e-Cu phase precipitated in a part protruding surface layer can be kept stable for an improved antimicrobial thereby an extended period of time.
[12]
How can a film adhesion method is most widely used as a shake flask method and for evaluating the antibacterial properties.
[13]
Shake flask method is a method that is mainly used for waterproof / water-repellent material and surface relief is severe and absorbent material is good material, the film adhesion method and material is smooth, and its products are mainly used for non-absorbent materials.
[14]
For the metal material is mainly evaluated the antimicrobial by a film adhesion method, it is common to evaluate by complying with JIS Z 2801 Standards. JIS Z 2801 apply mutatis mutandis to the case proceed with the antimicrobial evaluation, 0.5 ~ 0.85% NaCl there is to culture the bacteria for 24 hours using a containing inoculum, if proceed with the test in this condition the material for corrosion resistance, heat balcheong such as rust this phenomenon occurs.
[15]
If this phenomenon occurs balcheong is a problem that the reliability of the results of the evaluation of the antimicrobial material degradation.
[16]
This may be described as antibacterial evaluation bacterial culture after the balcheong developing the securing of corrosion resistance of a level not observed is essential.
Detailed Description of the Invention
SUMMARY
[17]
The present invention proposes a chromium carbide in the microstructure evenly distributed anti-microbial evaluation, while the high hardness excellent antibacterial property of not balcheong this phenomenon occurs after the material is also martensitic stainless steel and a method.
[18]
It is another object of the present invention will be derived by the person skilled in the art through the following examples.
Problem solving means
[19]
According to a preferred embodiment of the present invention, in weight%, C: 0.45 ~ 0.65%, N: 0.02 ~ 0.06%, Si: 0.1 ~ 0.6%, Mn: 0.3 ~ 1.0%, Ni: 0.1 ~ 0.4%, Cr : 13 ~ 14.5%, Mo: 0.4 ~ 0.6%, W: 0.8 ~ 1.2%, and Cu: 1.5 ~ containing 2.0% and the remainder Fe and unavoidable characterized in that it comprises an impurity in a high hardness antimicrobial excellent also martensite to site-based the stainless steel is provided.
[20]
The martensite-based stainless steel, there is a sites elongation can be placed appeal heat treatment performed is at least 18%.
[21]
In the martensitic stainless steel structure it may be performed by the heat treatment based on appeal to the 90 / 100㎛2 least chromium carbide distribution.
[22]
The martensitic stainless steel satisfies the formula I index (PREN) below, does the surface deterioration when the antimicrobial evaluation using a NaCl-containing inoculum occur, can exhibit a greater than 99% reduction of bacteria.
[23]
Within the index formula (PREN) Cr + 3.0 (Mo + 1/2 W) + 16N ≥ 17
[24]
Heat treatment based the appeal, the second cracking process of the martensite even distribution of chromium carbides in the first cracking process, the martensitic stainless steel tissue to uniformly distribute the Cu precipitate in the site-based stainless steel, tissue, and the chromium carbide the microparticles may comprise a third cracking process of spheroidization.
[25]
The first cracking process is going on in 500 ~ 600 ℃, the second cracking process is conducted at 800 ~ 900 ℃, the third cracking process may be carried out at 600 ~ 750 ℃.
[26]
The first cracking process is continued for 5 to 15 hours, wherein the second cracking process is continued for 15 to 25 hours, and the third cracking process may last for 5 to 15 hours.
[27]
Heat treatment based the appeal is, from after the first cracking process wherein the temperature raising process, the second cracking process of the third cracking process, after which the temperature was raised to of 40 ~ 200 ℃ / h speed up to the second cracking process a cooling process of cooling of at least 10 ℃ / h velocity, and the second may further include an air-cooling process, since the third cracking process.
[28]
Further, according to an embodiment of the present invention, there is provided a method of producing even a high hardness martensitic stainless steel excellent in antibacterial properties, to prepare a cast slab to hot-rolled steel sheet by hot rolling process; Performing softening operation by heat treatment based on appeal to the hot-rolled steel sheet; And said soft painter has completed producing the cold-rolled steel sheet comprising: cold rolling the annealed steel sheet; in the tissue of the first cracking process, the hot-rolled steel sheets which include, but, the heat treatment based the appeal is uniformly distributed to Cu precipitates in the structure of the hot rolled steel sheet a second cracking process, and the superior antimicrobial including three cracks process hardness of spheroidizing the fine particles of the chromium carbide to uniformly distribute the chromium carbide is also provided a method for producing martensitic stainless steel.
Effects of the Invention
[29]
According to the invention, Cu is added to the high carbon martensitic stainless steel appeal dunjae microstructure was uniform distribution of fine chromium carbide and e-Cu precipitation phase within the organization high hardness, high corrosion resistance and antibacterial property is excellent also for water martensitic stainless there are advantages to producing the steel.
[30]
According to the present invention, there is an advantage that does not occur in the developing balcheong antimicrobial material after evaluation.
Brief Description of the Drawings
[31]
Figure 1 is a chart showing the appeal based heat treatment process according to an embodiment of the present invention.
[32]
2 is a view showing a microstructure of Cu precipitates picture organization according to the Cu content in the first cracking process in accordance with one embodiment of the present invention.
[33]
3 is a view showing a picture of observing the material surface, since the anti-microbial evaluation, according to one embodiment of the invention.
Best Mode for Carrying Out the Invention
[34]
According to a preferred embodiment of the present invention, in weight%, C: 0.45 ~ 0.65%, N: 0.02 ~ 0.06%, Si: 0.1 ~ 0.6%, Mn: 0.3 ~ 1.0%, Ni: 0.1 ~ 0.4%, Cr : 13 ~ 14.5%, Mo: 0.4 ~ 0.6%, W: 0.8 ~ 1.2%, and Cu: 1.5 ~ containing 2.0% and the remainder Fe and unavoidable characterized in that it comprises an impurity in a high hardness antimicrobial excellent also martensite to site-based the stainless steel is provided.
Mode for the Invention
[35]
The invention will be described in bars, illustrated in the drawings certain embodiments that may have a variety of embodiments can be applied to various changes and detail in the Detailed Description. This, however, is by no means to restrict the invention to the specific embodiments, it is to be understood as embracing all included in the spirit and scope of the present invention changes, equivalents and substitutes. In describing the drawings was used for a similar reference numerals to like elements.
[36]
With reference to the accompanying drawings In the following, embodiments of the present invention will be described in detail.
[37]
Also for water material, such as the esophagus which is generally widely used, scissors, a scalpel razor and the medical instrument is a high hardness is required for the cutting performance and wear resistance maintained, a high corrosion resistance is required since the storage in the water and easily contact or wet atmosphere.
[38]
As a result, a material for water to do is that the added carbon martensitic stainless steel are mainly used.
[39]
In some cases for water and carbon Martensitic Steels, are widely used in 0.45 ~ 0.70% of carbon, up to 1.0% manganese, up to 1.0% silicon, and a material for water rivers also containing chromium of 12.0 ~ 15.0% by weight percentage.
[40]
In this case also for water and carbon martensitic stainless steels, it is prepared, including the appeal process based manufacturing material.
[41]
And during the appeal based material by the carbon and chromium reaction in the ferrite matrix to be fine particles of the chromium carbide form were dispersed precipitation, easy to apply stainless steel manufacturing processes, such as rolling and pickling according to the base within the employed carbon content becomes lower Do.
[42]
In addition, the ferrite base fine chromium carbides uniformly distributed in the tissue is distributed also to allow for fast re-employment of chromium and carbon to the high-temperature austenite in done strengthening heat treatment process in distribution the manufacturer, and then quenching the hardness of the martensite structure and is an important factor for improving the corrosion resistance.
[43]
The hardness, corrosion resistance, it is necessary to uniformly distributed within the high degree and for water in order to ensure the carbon martensitic steel microstructure fine chromium carbides tissue.
[44]
On the other hand, as we have seen, in the case of a metal material it may cause the anti-microbial evaluation balcheong phenomenon may occur a problem in that even for water and the reliability of the anti-microbial evaluation reduced even when carbon martensitic steel.
[45]
Antibacterial Maarten Patent site-based stainless steel and is associated, e-Cu Japanese Patent Laid-Open Publication of a precipitated phase in the uniform distribution is excellent martensitic stainless steel and a manufacturing method in which the antibacterial Hei 9-195016, Japanese Unexamined Patent Publication (Kokai) Although the like 9-256116, it was confirmed to be without any information about the factors is determined to have a significant effect on anti-microbial and bacterial reduction rate, such as anti-microbial evaluation of rust material.
[46]
Consequently, it is essential to secure the corrosion resistance, antibacterial properties is that excellent hardness in order to develop a martensitic stainless steel, while the chromium carbide in the microstructure is not uniformly distributed balcheong has occurred since the antimicrobial material evaluation.
[47]
[48]
The invention written as a high hardness is excellent in antibacterial also relates to a martensitic stainless steel and a method of manufacturing the same, in weight%, C: 0.45 ~ 0.65%, N: 0.02 ~ 0.06%, Si: 0.1 ~ 0.6%, Mn: 0.3 ~ 1.0%, Ni: 0.1 ~ 0.4%, Cr: 13 ~ 14.5%, Mo: 0.4 ~ 0.6%, W: 0.8 ~ 1.2%, and Cu: containing 1.5 to 2.0% and the remainder Fe and unavoidable alloy consisting of impurities has the components, characterized in that the bacteria reduction rate in JIS Z 2801 antibacterial evaluation manufacturing a martensitic stainless steel showing a 99.9% or more.
[49]
Of the present invention for water and will be described with respect to the content of alloy elements constituting the carbon martensitic stainless steel.
[50]
C is added more than 0.45%, the hardness after heat treatment enhanced cutting performance martensitic stainless steels is reduced if the content is low and abrasion resistance is not secured, so. On the other hand, limit an upper limit to the content is excessively increases, chromium carbide due to the excessive formation as well as reduced corrosion resistance of the material itself, so that the annealing in the organization concerned coarse carbides formed due to the segregation of carbon to 0.65%.
[51]
N has the advantage that, even if not added as an element to be added to improve the corrosion resistance and hardness at the same time, instead of C not induce local micro-segregation not form a precipitate of crude product. To implement this effect and the addition of 0.02% or more. However, if excessively added because it may result in the pore (pore) caused by the casting nitrogen limits the upper limit is set to 0.06%.
[52]
Si is essential, after addition of 0.1% or more because it is an element to be added as for deoxidation. However, Si added in a high content is to lower the pickling performance, so increasing the brittleness of the material and limits the upper limit of 0.6%.
[53]
Since Mn is an element that is essential to the addition of the addition of more than 0.3% for deoxidation. However, if the excess is added to inhibit the river surface quality is suppressed to secure a high hardness properties through the final heat treatment material is retained austenite formed so limits the upper limit is set to 1.0%.
[54]
Ni is added as an element that is unavoidably brought from the steel scrap in a steelmaking process, at least 0.1%. However, when containing a high content of Ni to form the final heat-treated material retained austenite high hardness is difficult to obtain physical properties. This restricts the upper limit is set to 0.4%.
[55]
Since Cr is a basic element for securing corrosion resistance, and addition of more than 13%. However, the excessive addition of the production cost is increased, to increase the fine segregation of the chromium component tissue to locally cause a coarsening of the chromium carbide limits the upper limit it is possible to lower the corrosion resistance and the hardness of material strengthening heat treatment at 14.5% .
[56]
Since Mo has excellent effects in improving corrosion resistance is added to more than 0.4%. However, the excessive addition is limited to the upper limit to 0.6%, as they result in the increase in manufacturing cost.
[57]
W, so the effect of increasing the corrosion resistance and heat treatment hardness is added to more than 0.8%. However, it inhibits the rise in the manufacturing cost and workability upon excessive addition limits the upper limit is set to 1.2%.
[58]
Cu is an antimicrobial ensure it is possible to form the e-Cu by the appeal placed as the most important alloying element in the stainless steel of the present invention. Also it becomes large the amount of precipitation of the content is more e-Cu but improves the antimicrobial properties to increase the amount of elution of Cu2 +, if excessively added to the composition, limits the workability, the upper limit, it may cause can corrosion resistance is decreased to 2.0% do.
[59]
[60]
Martensitic stainless steel according to one embodiment of the present invention having a composition as described above is prepared by continuous casting or a slab produced by an ingot casting, and then hot-rolled steel sheet is possible by processing the hot rolling process.
[61]
After manufacturing the hot-rolled steel sheet is carried out also the softening operation by the heat treatment based on appeal to a good processability secured before proceeding to the processing such as precision rolled to a thickness as possible to use for water.
[62]
As shown in Figure 1, the heat treatment based on appeal in accordance with one embodiment of the present invention is chromium in the organization of the martensitic first cracking process of stainless preferentially uniform distribution of the Cu precipitates spherical in the lecture tissue and, the hot-rolled steel sheet a second cracking process, and a third process of crack spheroidized fine particles of chromium carbide to uniformly distribute the carbide.
[63]
The first cooling stage after the cracking process to lower the temperature to the hot-rolled steel sheet down to the third cracking process after the second temperature increase process, the second cracking process of raising the temperature of the hot-rolled steel sheet down to the cracking process, and, the more the air-cooling process consists of cooling the hot-rolled steel sheet after the three-cracking process.
[64]
Firstly, the first cracking process in accordance with one embodiment of the present invention is a process to uniformly distribute the Cu precipitates in the structure of hot-rolled steel sheet, the uniform heating of the hot-rolled steel sheet in a constant-temperature atmosphere of 500 ~ 600 ℃ for 5-15 hours It is a process.
[65]
In the process, fine Cu precipitates are present in several tens of nm in size and uniformly distributed in the tissue as shown in (b) of Fig. The Cu deposit is typically acts as the starting point of the precipitated chromium carbide is well known that the first precipitate at the grain boundaries leads to precipitation of chromium carbides uniformly in the second process since the crack.
[66]
When the first cracking process, the cracking temperature 500 ℃ less than in not a Cu precipitate is formed, in the case of 600 ℃ than at the same time Cu precipitate as chromium carbides are simultaneously deposited, regardless of the Cu precipitates and chromium carbide is preferentially precipitated in the grain boundaries finer It can not ensure a uniform distribution of carbides.
[67]
In addition, in the case the soaking time in the first cracking process is less than 5 times Cu precipitation is to secure uniform distribution of chromium carbides can not not generated, and localized to the count is decreased while increasing the size of Cu precipitates exceeds 15 hours occurs a problem that the Cu precipitate distribution and it is difficult as a result, uniform distribution of chromium carbide secured.
[68]
The first cracking process it is desirable to process the crack for 5 to 15 hours at a constant temperature environment of 500 ~ 600 ℃.
[69]
Next day the temperature rising stage in accordance with an embodiment of the present invention is the process of heating the hot-rolled steel sheet to a first cracking process after the second cracking process at a rate of 40 ~ 200 ℃ / h.
[70]
If the heating rate in the temperature rising stage at not more than 40 ℃ / h, the chromium carbide coarsening become the temperature range, for example, a bar that increases the time of passing a 700 ~ 750 ℃, becomes the size of the chromium carbide coarse chrome distributed in the microstructure is the density of the carbides can be reduced.
[71]
On the other hand, if the temperature rising rate is 200 ℃ / h or higher, the chromium carbide is jo this dialog through the temperature interval of time which is reduced advantage of being able to secure a fine chromium carbides, but the carbide diffusion time is reduced chromium carbide distribution imbalances this drawback resulting there.
[72]
Therefore, it is preferable that the temperature raising rate in the temperature rising stage exceed 40 ℃ / h and adjusted to 200 ℃ / h less than the range.
[73]
Subsequently, 15 of a process of the second cracking process in accordance with one embodiment of the present invention is uniformly distributed chromium carbides in the structure of the progress following the raising step the hot-rolled steel sheet, hot-rolled steel sheet in a constant-temperature atmosphere of 800 ~ 900 ℃ ~ for 25 hours the process of uniformly heated. In this process, chromium carbides are uniformly distributed within the organization.
[74]
The cracking temperature may be agglomerated portion is formed due to the chromium carbide is locally precipitated in the grain boundaries at the time of soaking is less than 800 ℃, and when more than 900 ℃ bar that chromium carbide coarse in the vicinity of the grain boundary formed, these chromium carbides agglomerated portion and chromium carbide for crude material by causing a localized imbalance of material and to ensure the ductility is difficult, resulting in the final heat treatment when the material deterioration.
[75]
Further, the chrome a second if the soaking time is not more than 15 hours in the cracking process, the fine chromium carbides formed in the glass, but chromium carbide is not uniformly distributed, may be crowded distributed, neighbor by the under-based is at least 25 hours carbonaceous polymer, but is a localized chromium carbide coarsening progress of course, the process efficiency is decreased to increase the heat treatment time, and there is a disadvantage that the manufacturing cost increases.
[76]
Thus, the second cracking process it is desirable to process the crack for 15 to 25 hours at a constant temperature environment of 800 ~ 900 ℃.
[77]
Next, the cooling process, according to one embodiment of the present invention, the second cracking process after the third cracking hot-rolled steel sheet to process as the process of cooling to 600 ~ 750 ℃, cooling the hot rolled steel sheet at a rate in excess of 10 ℃ / h it is preferable to. If the cooling rate is 10 ℃ / h or less, chromium carbide which is the size of the microstructure increases the time passing through the temperature range in which coarse bar, which results is the coarse chromium carbide microstructure in the microstructures, strengthening heat treatment the corrosion resistance and hardness becomes difficult to secure.
[78]
As a process of the proceeding followed third cracking process, the cooling process, according to one embodiment of the present invention, visualization of fine particles of the chromium carbide hot-rolled steel sheet structure at low temperatures, the hot-rolled coil at 600 ~ 750 ℃ ​​with constant temperature for 5-15 hours maintained, the process of uniformly heated.
[79]
Chromium carbide is a minimum temperature condition is 600 ℃ for visualization, and if it exceeds 750 ℃ ​​grow excessively the spheroidizing chromium carbides to reduce the number of chromium carbide, and the ductility is lowered.
[80]
Further, the third constant-temperature keeping time of the cracking process is less than 5 hours, and the spheroidization of the chromium carbide proceeds insufficient, to form a microstructure of not less than 15 hours is tank spheroidized carbides in excessive growth.
[81]
Thus the third process, the crack is preferably treated cracking for 5 to 15 hours at a constant temperature environment of 600 ~ 750 ℃.
[82]
The complete the heat treatment process based on appeal to the air-cooling the hot-rolled steel sheet in the air after the cracking process 3.
[83]
[84]
And cold-rolled steel sheet manufacturing method comprising: cold rolling a steel sheet after annealing upset soft through the heat treatment based on appeal of the finished progresses, a step of heat treatment strengthened cold-rolled steel sheet using the processing is completed to the desired thickness and shape proceeds.
[85]
Enhanced heat treatment proceeds in a total of three steps, the first step is an austenite age ranging → quenching heat treatment step of re-employment carbide was uniformly distributed by the appeal placed.
[86]
This heat treatment step, the heat treatment at 1000 ℃ to 1150 ℃ for 10 seconds to 5 minutes. Here, when the heat treatment temperature is lower than 1000 ℃ no for razor blade steel to obtain the required hardness, the problem in the case where the heat treatment temperature exceeds 1150 ℃, hardness lowered with the retained austenite hyperplasia carbides of stock in accordance with the capacity increase occurs It can be.
[87]
Further, even if case the heat treatment time is less than 10 seconds can not be also obtained the hardness required for the steel blade, the heat treatment time exceeds 5 minutes, the grain (grain) growth, and may be retained austenite occurs.
[88]
After the quench is complete the heat treatment is carried some retained austenite to approximately -70 ℃ 10 seconds to about 5 minutes heat treatment at a temperature of sub - zero in order to phase transformation to martensite. After subjected to about 400 ~ 600 ℃ tempering process to secure the manufactured martensitic Steel flexible 30-2 minutes, and was air-cooling heat treatment process to complete the reinforcement.
[89]
The following describes the present invention through the embodiments of the present invention. However, the examples are a preferred embodiment of the present invention, without being limited by the to the scope of the present invention embodiment.
[90]
[91]
First, containing a composition as shown in Table 1 below and the other was prepared in the hot-rolled steel sheets according to the Examples and Comparative Examples that iron (wt.%) Containing (Fe) and unavoidable impurities. Note One way is within the formula of the index indicator points to evaluate the corrosion resistance of stainless steel to attach a (PREN, Formula 1) was prepared for evaluation of corrosion resistance between the steel grade.
[92]
수식 1) PREN=Cr+3.0(Mo+1/2 W)+16N
[93]
TABLE 1
Grades C And Mn Cr Ni you W With N TAKES
Comparative Example 1 0.683 0.408 0.693 13.21 0.308 0 0 0 0.03 13.69
Comparative Example 2 0.687 0.402 0.730 13.24 0.296 0 0 0.51 0.04 13.88
Comparative Example 3 0.651 0.4 0.688 13.3 0.299 0 0 1.02 0.06 14.26
Comparative Example 4 0.700 0.380 0.638 12.76 0.310 0 0 1.46 0.03 13.24
Comparative Example 5 0.692 0.424 0.722 13.55 0.302 0 0 1.98 0.05 14.35
Comparative Example 6 0.695 0.391 0.701 13.16 0.3 0 0 2.52 0.04 13.8
Comparative Example 7 0.49 0.305 0.517 13.98 0.307 0.51 1.05 0 0.031 17.69
Comparative Example 8 0.56 0.313 0.472 13.81 0.295 0.49 1.01 0 0.029 17.36
Comparative Example 9 0.62 0.298 0.505 14.01 0.308 0.51 1.03 0 0.03 17.67
Comparative Example 10 0.66 0.312 0.528 13.92 0.310 0.48 1.02 1.50 0.028 17.44
Example 1 0.45 0.297 0.489 13.91 0.287 0.48 0.99 1.52 0.029 17.40
Example 2 0.5 0.299 0.506 14.14 0.302 0.49 0.95 1.5 0.03 17.61
Example 3 0.56 0.298 0.509 14 0.301 0.5 1 1.52 0.03 17.58
Example 4 0.6 0.291 0.503 13.95 0.305 0.49 0.98 1.5 0.03 17.47

[94]
And also for water having the composition described in the above Table 1 to prepare a carbon martensitic stainless steel slab and hot-rolled steel sheets were prepared (thickness: 3mm) through the hot rolling, and at the same time make the edge quality of the hot-rolled material.
[95]
Then, after carrying out the heat treatment using the conditions placed to appeal of using the produced hot rolled steel sheet was performed for microstructural observation and elongation rating.
[96]
[Appeal based heat treatment conditions;
[97]
- a first cracking process: 10 hours at 500 ℃
[98]
- raising step: temperature increase rate 100 ℃ / hr
[99]
- a second cracking process: 20 hours at 850 ℃
[100]
- cooling process: a temperature lowering speed of 10 ℃ / hr
[101]
- third cracking process: 7 hours at 650 ℃
[102]
Then, the cold-rolled steel sheets were prepared (thickness: 1.5mm) by a cold rolling, it was confirmed that the edge quality of the rolled material.
[103]
Further, after performing a heat treatment strengthened under the following conditions it was carried out for antibacterial evaluation by using the strain (E. coli), one kind of in complying with JIS Z 2801.
[104]
[Strengthening heat treatment conditions;
[105]
- Austenitizing: 5 min at 1100 ℃
[106]
- Quenching: oil quenching at room temperature
[107]
- Deep freezing: -70℃에서 5분
[108]
- Tempering/Sintering: 500℃에서 30분
[109]
In addition, the balcheong development for the completion of the evaluation material was subjected to surface observation to confirm / oil radish. The results are shown in Table 2.
[110]
TABLE 2
Grades Hot rolled edge quality Appeals dunjae material Quality cold-rolled edge Enhanced heat treated material
Elongation (%) Precipitate uniformity Surface balcheong Bacteria Reduction (%)
Cr carbide With 석출 상
Comparative Example 1 Good 21.1 Disadvantage Disadvantage Good U 99.9
Comparative Example 2 Good 20.8 Disadvantage Disadvantage Good U 99.9
Comparative Example 3 Good 19.3 Disadvantage Disadvantage Good U 99.9
Comparative Example 4 Good 19.2 Good Good Good U 99.9
Comparative Example 5 Good 19.2 Good Good Good U 99.9
Comparative Example 6 Disadvantage 17.5 Good Good Disadvantage U 99.9
Comparative Example 7 Good 21.4 Good Good Good radish 92.5
Comparative Example 8 Good 21.1 Good Good Good radish 94.1
Comparative Example 9 Good 20.4 Good Good Good radish 94.4
Comparative Example 10 Good 17.3 Good Good Disadvantage radish 99.9
Example 1 Good 21.6 Good Good Good radish 99.9
Example 2 Good 20.1 Good Good Good radish 99.9
Example 3 Good 19.8 Good Good Good radish 99.9
Example 4 Good 19.4 Good Good Good radish 99.9

[111]
If more than that, whereas, Cu content of 2.5% observed (Comparative Example 6), and confirmed that a large amount of cracks in the outer edges of the after hot rolling material occurs, which is likely due to the hot workability disadvantage of the large amount of Cu added . Only after the appeal was not based elongation rating of less than 18%.
[112]
In order to ensure good hot workability on the basis of the above results it can be seen that the Cu content should be limited to no more than 2%.
[113]
On the other hand, placing the other hand, represents the case where the addition of Mo, W, etc. (Comparative Example 7-10, Example 1-4) In the case of the preferred, regardless of the C amount of 0.45 ~ 0.70% the hot rolling property in order to improve the corrosion resistance, appeal then if the C content when proceeding cold rolling is more than 0.65%, and confirmed to be a large amount of cracks in the cold-rolled steel sheet edge portions, it has been confirmed that the observed elongation as low as less than 18% after placed appeal as well. This not only formation of coarse carbides due to the large amount of C is added W, it is determined to be due to the formation of the Cu precipitates such as the additional element.
[114]
In order to ensure good cold workability based on the above results it can be seen that the content of C should be limited to not more than 0.65%.
[115]
In addition, it was confirmed that chromium carbides and Cu precipitates through a micro structure observation of the appeal dunjae.
[116]
First, in the comparative example for 1-6 when the uniformity of chromium carbides increase it was confirmed that as the content of Cu increases from 0 to 2.5% in certain C content, in particular, be a Cu content added in 1.5% or more bases 90 dog / 100㎛2 be more than the carbide density to ensure it is determined that the securing of excellent corrosion resistance and high hardness after heat treatment be enhanced customer.
[117]
On the other hand, when the Cu content to be added more than 1.5% were found to be uniformly distributed as shown in the annealing tissue 2 (b) also Cu precipitation phase within the distribution.
[118]
More specifically, it is possible to also cause the disadvantage of the antimicrobial to the formation of the Cu non-uniform precipitation if the Cu content added in less than 1.5%, such as 2 (a). On the other hand, if more than 1.5% in Fig. 2 (b) was added Cu precipitation phase uniformly distributed in the base, and is determined to be a superior anti-microbial expression through it.
[119]
In order to assure high hardness excellent corrosion resistance and antibacterial properties of the basis of these results it can be seen that should be limited to one to be the content of Cu is added over 1.5%, Cu addition amount when considering the workability of the material to less than 1.5 ~ 2.0% .
[120]
[121]
After completion of heat treatment after reinforced by using a hot-rolled steel sheets it was confirmed balcheong surface phenomenon or absence of antimicrobial material and subsequent evaluations.
[122]
The first, comparing the antimicrobial evaluation and evaluation of the surface material according to the developing balcheong Cu addition amount with respect to Mo, the material W is not added in Examples 1 to 6 was observed. As a result, it was confirmed to exhibit high antibacterial properties of the 99.9% irrespective of the added amount of Cu.
[123]
However, the evaluation results of the observation of the surface layer of the material is completed, it was confirmed that the surface balcheong developer according to inferior corrosion resistance as shown in FIG. 3 (a) depth. Thus, expression of anti-microbial or whether the cause is due to the effect of the Cu contained in the material itself, such as fruit and vegetables is to determine whether the indefinite length due to the effect of Fe ions eluted from rusting.
[124]
Therefore, to ensure that a reliable quantitative evaluation, the corrosion resistance improvement of the material does not cause deterioration of the surface layer, such as a phenomenon of inhibition balcheong antibacterial evaluation material is required.
[125]
On the other hand, to the corrosion resistance improvement Mo, for which the steel sheet is added over the W amount (Comparative Examples 7 to 10 and Examples 1 to 4) Figure 3 (b) and altered surface layer, such as balcheong phenomena in the material after the antimicrobial evaluation as of it was confirmed that this is not formed. I.e. became OK Cr, Mo, W, In the case of N, such as the steel sheet components dissolved by setting the one within the formula index (PREN) values ​​indicated in Equation 1) of the above is at least 17, which is not observed the antimicrobial evaluation balcheong phenomenon .
[126]
For such non-antimicrobial evaluation of that material to improve the corrosion resistance resulting Cu added steel (comparative example 7-9) at least 1.5% of the content of the other hand, Cu represents the bacteria reduction rate for the column of less than 95% of the added steel ( Comparative example 10 and example 1-4) was confirmed to be excellent antimicrobial properties of the 99.9% of the expression.
[127]
In order to secure the excellent antimicrobial properties based on the above results, if you set the PREN value of at least 17, and the addition of more than 1.5% Cu by adding elements for improving the corrosion resistance of the same material as Mo, W not only be excellent in antibacterial characteristic obtained rather, it can be seen that it is possible to ensure a high reliability antibacterial evaluation results are balcheong then developed antibacterial evaluation is suppressed.
[128]
From the above results in weight percent in accordance with the present invention, C: 0.45 ~ 0.65%, N: 0.02 ~ 0.06%, Si: 0.1 ~ 0.6%, Mn: 0.3 ~ 1.0%, Ni: 0.1 ~ 0.4%, Cr: 13 ~ 14.5%, Mo: appeal of 1.5 to containing 2.0% and the rest is present in the present invention with respect to the martensitic stainless steel of Fe and unavoidable contain impurities conditions: 0.4 ~ 0.6%, W: 0.8 ~ 1.2%, and Cu when applied to a dull and enhance heat treatment complying JIS Z 2801 does not occur the phenomenon when balcheong antibacterial evaluation it can be seen that a high hardness manufactured martensitic stainless steel, the reduction rate of bacteria exhibiting excellent antimicrobial activity of 99.9% or more are possible.
[129]
In the present invention, as described above been described by the specific details and exemplary embodiments and drawings, such as specific configuration elements, which only be provided to assist the overall understanding of the invention, the invention is not limited to the embodiment of the , those of ordinary skill in the art to which the invention pertains that various modifications, additions and substitutions are possible from this disclosure. Thus, the idea of ​​the invention is limited to the described embodiments jeonghaejyeoseo will not be, all to be described later claims as well as the appended claims and equivalents, or if the equivalent strain ones will to fall within the scope of the inventive idea .

Claims
[Claim 1]
By weight%, C: 0.45 ~ 0.65%, N: 0.02 ~ 0.06%, Si: 0.1 ~ 0.6%, Mn: 0.3 ~ 1.0%, Ni: 0.1 ~ 0.4%, Cr: 13 ~ 14.5%, Mo: 0.4 ~ 0.6%, W: 0.8 ~ 1.2%, and Cu: 1.5 ~ 2.0%, and the remainder containing Fe and inevitable excellent antibacterial dimension comprising the impurities martensitic stainless steel.
[Claim 2]
According to claim 1, wherein the martensitic also excellent in antibacterial properties high hardness, characterized in that elongation of the stainless steel is at least 18% martensitic stainless steel to.
[Claim 3]
Claim 2 wherein the martensitic stainless steel 90 within the tissue / excellent antibacterial hardness to that of the above chromium carbide distribution 100㎛2 characterized Fig martensitic stainless steel to.
[Claim 4]
The method of claim 3, wherein the martensitic stainless steel satisfies within formula index (PREN) below, does the surface deterioration when Antimicrobial Evaluation of the inoculum the NaCl-containing occur, the antimicrobial representing more than 99% bacterial reduction high hardness martensitic stainless steel. Within the index formula (PREN) Cr + 3.0 (Mo + 1/2 W) + 16N ≥ 17
[Claim 5]
Claim 2 to 4 according to any one of claims, wherein the first cracking process to put appeal heat treatment for the martensitic stainless steel produced is evenly distributed to Cu precipitates in the martensitic stainless steel tissue, the martensite a second cracking process of uniform distribution of the chromium carbides in the stainless steel-based tissue site, and the superior antimicrobial including three cracks process hardness of spheroidizing the fine particles of the chromium carbide also martensitic stainless steel.
[Claim 6]
The method of claim 5, wherein the first cracking process is going on in 500 ~ 600 ℃, the second cracking process is conducted at 800 ~ 900 ℃, the third cracking process is excellent in antibacterial progress at 600 ~ 750 ℃ high hardness martensitic stainless steel.
[Claim 7]
The method of claim 6, wherein the first cracking process is continued for 5 to 15 hours, wherein the second cracking process is continued for 15 to 25 hours, and the third cracking process is excellent in antibacterial properties and continuing for 5-15 hours high hardness martensitic stainless steel.
[Claim 8]
The method of claim 7, wherein the appeal based heat treatment, the above after the temperature raising process, the second cracking process of the first cracking process temperature was increased to 40 ~ 200 ℃ / h speed of up to the second cracking process after the 3 is excellent in antimicrobial further comprises air-cooling process, the cooling process and, after the third hardened cracking process to cool by more than 10 ℃ / h speed through to the crack course also martensitic stainless steel.
[Claim 9]
A high hardness is excellent in antibacterial FIG method martensitic stainless steel, the method comprising preparing a cast slab to hot-rolled steel sheet by hot rolling process; Performing softening operation by heat treatment based on appeal to the hot-rolled steel sheet; And said soft painter has completed producing the cold-rolled steel sheet comprising: cold rolling the annealed steel sheet; in the tissue of the first cracking process, the hot-rolled steel sheets which include, but, the heat treatment based the appeal is uniformly distributed to Cu precipitates in the structure of the hot rolled steel sheet a second cracking process, and a third process of cracking a high hardness with excellent antibacterial FIG method martensitic stainless steel comprising a visualization of the fine particles of the chromium carbide to uniformly distribute the chromium carbide.
[Claim 10]
10. The method of claim 9, wherein the procedure proceeds for a cracking process, is 5 ~ 15 hours at 500 ~ 600 ℃, the second cracking process is conducted for 15 to 25 hours at 800 ~ 900 ℃, the third cracking process at 600 ~ 750 ℃ ​​5 ~ 15 sigan excellent antibacterial hardness is in progress is also method for producing martensitic stainless steel for.
[Claim 11]
11. The method of claim 10, wherein an appeal based heat treatment, the above after the temperature raising process, the second cracking process of the first cracking process temperature was increased to 40 ~ 200 ℃ / h speed of up to the second cracking process after the 3 the cooling stage and the third further comprises a method of producing an antimicrobial excellent high-hardness martensitic stainless steel of the air-cooling process after the cracking process of up to the cracking process, cooling to at least 10 ℃ / h speed.
[Claim 12]
12. The method of claim 11, wherein performing the strengthening heat treatment to the cold-rolled steel sheet; further comprising the strengthening heat treatment, the chromium carbide was uniformly distributed in 1000 ℃ to 1150 ℃ in order to re-employed for 10 seconds to five minutes austenite age ranging processing, the method comprising sub - treatment agent at a temperature of -70 ℃ 10 seconds to 5 minutes, 30 minutes at 400 ~ 600 ℃ in order to phase transformation step of quenching to room temperature, the residual austenite to martensite 1-2 hardened antimicrobial comprising tempered for a time also excellent method for producing martensitic stainless steel.