CN113174544B - Superplastic forming nanocrystalline antibacterial martensitic stainless steel and preparation method thereof - Google Patents
Superplastic forming nanocrystalline antibacterial martensitic stainless steel and preparation method thereof Download PDFInfo
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
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- C22C38/00—Ferrous alloys, e.g. steel alloys
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- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
- C21D8/005—Modifying the physical properties by deformation combined with, or followed by, heat treatment of ferrous alloys
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- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/20—Ferrous alloys, e.g. steel alloys containing chromium with copper
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- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
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Abstract
The invention relates to the technical field of materials, and discloses superplastic forming nanocrystalline antibacterial martensitic stainless steel and a preparation method thereof. The stainless steel comprises the following chemical components: c:0.16 to 0.32; cr:12.8 to 14.4; cu:1.4 to 3.0; w:1.2 to 2.8; v:0.04 to 0.20; la:0.01 to 0.03; mn is less than 0.15; n is less than 0.03; the balance being Fe. The preparation method of the stainless steel comprises the following steps: (1) Keeping the temperature of 980-1060 ℃ for a period of time and then rapidly cooling to room temperature; (2) At the temperature of 820-900 ℃ and the strain rate of 0.1-1 s ‑1 The total strain amount is more than or equal to 70 percent, so that the precursor of the nano lath is converted into an equiaxed nano crystal structure; (3) Under the conditions of temperature of 760-840 ℃ and strain rate of 0.001-0.02 s ‑1 Superplastic forming is carried out under the conditions of (1). (4) Aging the superplastic formed material at 460-500 deg.C for 3-5 h. The superplastic forming nanocrystalline antibacterial martensitic stainless steel prepared by the invention has excellent hot working performance, corrosion resistance, antibacterial performance and comprehensive mechanical properties, and can be widely applied to medical instruments in the cutting fields of knives, scissors and the like.
Description
Technical Field
The invention relates to the technical field of materials, in particular to superplastic forming nanocrystalline antibacterial martensitic stainless steel and a preparation method thereof.
Background
The copper-containing antibacterial martensitic stainless steel is formed by adding a Cu element with a broad-spectrum antibacterial function into the traditional martensitic stainless steel, and utilizing Cu ions which are continuously released in the process of contacting with a medium solution environment to participate in the sterilization process of bacteria. The copper-containing antibacterial martensitic stainless steel is applied to the preparation of cutting medical instruments such as scalpels, surgical scissors and the like, and the risk of bacterial infection in the operation process is expected to be remarkably reduced. However, the copper-containing antibacterial martensitic stainless steel also reveals the following two disadvantages in the practical use process: firstly, the addition of Cu leads to the remarkable reduction of the hot working performance of the material, which greatly increases the cost of hot working of the material; secondly, the Cu-rich phase precipitated during aging can impart antibacterial properties to the material, but is not negligible for the reduction of the corrosion resistance of the material.
Compared with the traditional coarse-grain metal material, the nano-grain metal material not only has the advantage of high-temperature superplasticity, but also has good corrosion resistance. Based on the method, the prepared nanocrystalline copper-containing antibacterial martensitic stainless steel can make up the defects of the current copper-containing antibacterial martensitic stainless steel, and a new direction is provided for the development of novel antibacterial martensitic stainless steel. At present, the preparation of bulk nanocrystalline metal materials is mainly achieved by a large plastic deformation (SPD) method. Common large plastic deformation methods comprise Equal Channel Angular Pressing (ECAP), accumulative composite rolling (ARB), multidirectional Forging (MF), high Pressure Torsion (HPT) and the like, all of which need high-power equipment and expensive dies, and the prepared material has smaller size and cannot meet the requirement of large-scale industrial production. Therefore, the invention provides novel antibacterial martensitic stainless steel, which can realize the nanocrystallization of crystal grains through conventional hot rolling deformation and can realize superplastic forming, thereby bringing new foundation and opportunity for the development of copper-containing antibacterial martensitic stainless steel.
Disclosure of Invention
The invention aims to provide superplastic forming nanocrystalline antibacterial martensitic stainless steel, and in order to achieve the aim, the technical scheme of the invention is as follows:
a superplastic forming nanocrystalline antibacterial martensitic stainless steel is characterized in that: the stainless steel comprises the following chemical components in percentage by weight: c:0.16 to 0.32; cr:12.8 to 14.4; cu:1.4 to 3.0; w:1.2 to 2.8; v:0.04 to 0.20; la:0.01 to 0.03; mn is less than 0.15; n is less than 0.03; the balance being Fe. Preferred ranges for some of the elements are: c:0.24 to 0.28; cr:13.6 to 14.0; cu:2.2 to 2.6; w:2.0 to 2.4; v:0.12 to 0.16.
The invention also aims to provide a preparation method of the superplastically formed nanocrystalline antibacterial martensitic stainless steel, which comprises the following steps: smelting in a vacuum induction furnace to obtain a raw material ingot, polishing the ingot, cogging and forging at the temperature of over 1100 ℃, and finish forging to obtain a blank. Maintaining the temperature of the blank obtained by the finish forging processing at 980-1060 ℃ for a period of time, and then rapidly cooling to room temperature to obtain a nano lath precursor; thermally deforming the obtained nano-lath precursor to obtain an equiaxed nano-crystalline structure; superplastic forming of a material with equiaxed nanocrystalline structure; and carrying out aging treatment on the molded material to finally obtain the nanocrystalline antibacterial martensitic stainless steel.
The nano lath precursor has the temperature of 820-900 ℃ and the strain rate of 0.1-1.0 s -1 Carrying out thermal deformation under the condition of (1), wherein the total strain amount is more than or equal to 70 percent, and obtaining an equiaxed nanocrystalline structure after thermal deformation.
The obtained material with equiaxial nanocrystalline structure has the strain rate of 0.001-0.02 s at the temperature of 760-840 DEG C -1 Superplastic forming is carried out under the conditions of (1).
As a preferable technical scheme:
and (3) keeping the temperature of the blank obtained by the finish forging processing at 1020-1040 ℃, wherein the heat preservation time t = (1-2) D min, wherein D is the effective thickness of the sample, and the unit is mm. And (3) immediately and quickly cooling to room temperature after heat preservation, wherein the cooling rate is controlled to be between 2 and 20 ℃/s, and the nano-strip precursor can be obtained after cooling.
The nano lath precursor is subjected to strain rate of 0.2-0.5 s at the temperature of 860-880 DEG C -1 The total strain is more than or equal to 90 percent, and the nano-lath precursor can be converted into an equiaxed nano-crystalline structure after thermal deformation.
For equiaxed nanocrystalline material, the temperature is 800-820 ℃, and the strain rate is 0.002-0.005 s -1 Superplastic forming under the conditions of (1).
After superplastic forming, aging for 3-5 h at 460-500 ℃.
The beneficial effects of the invention are:
(1) Compared with the prior art, the antibacterial martensitic stainless steel provided by the invention can be prepared by conventional hot rolling deformation without depending on high-power equipment and expensive dies.
(2) Compared with the prior art, the method for preparing the bulk nanocrystalline metal material is not limited by the size, so that the requirement of large-scale industrial production can be met.
(3) The method can obviously improve the hot forming performance of the martensitic stainless steel.
(4) Under the conditions of optimized alloy components (C: 0.24-0.28, cr 13.6-14.0, W2.2-2.6, V0.12-0.16 and thermal deformation (the temperature of a nano-lath precursor is 860-880 ℃, the strain rate is 0.2-0.5 s -1 The total strain amount is more than or equal to 90 percent), and the prepared nanocrystalline antibacterial martensitic stainless steel has more excellent antibacterial performance, good corrosion resistance and excellent comprehensive mechanical property. The antibacterial rate is up to more than 99%, the tensile strength is 1660-1820 MPa, the elongation is 12-16%, the Vickers hardness is 500-540, and the pitting potential is higher than 0.3mV.
(5) The superplastic forming nanocrystalline antibacterial martensitic stainless steel prepared by the invention can be widely applied to medical instruments in the cutting fields of knives, scissors and the like.
Drawings
FIG. 1 TEM photograph of a nanostring precursor.
FIG. 2 is a TEM photograph of equiaxed nano-crystalline structure formed by thermally deforming a nano-slab precursor.
FIG. 3 is a photograph of the superplastic drawing of nanocrystalline, antibacterial martensitic stainless steel.
(a) A sample before stretching; (b) a photograph of the 2Cr13Cu3 after high temperature stretching; (c) Photograph of stainless steel according to example 7 of the present invention after high temperature drawing.
FIG. 4 is a photograph showing the effect of the nano-crystalline antibacterial martensitic stainless steel on killing Staphylococcus aureus.
(a) 2Cr13 and bacteria are co-cultured for 24 hours; (b) co-culturing 2Cr13Cu3 and bacteria for 24 h; (c) The stainless steel of example 7 of the present invention was co-cultured with the bacteria for 24 hours.
Detailed Description
In order to make the purpose, technical solution and effect of the present application clearer and clearer, the present application is further described in detail below with reference to the accompanying drawings and examples.
The invention provides superplastic forming nanocrystalline antibacterial martensitic stainless steel which comprises the following chemical components: c:0.16 to 0.32; cr:12.8 to 14.4; cu:1.4 to 3.0; w:1.2 to 2.8; v:0.04 to 0.20; la:0.01 to 0.03; mn is less than 0.15; n is less than 0.03; the balance being Fe.
Please refer to fig. 1-2. FIG. 1 shows the nano-lath precursor formed by rapidly cooling the material of example 7 of the present invention, and the width of the lath is between 45 nm and 65nm as seen from the TEM tissue photograph. FIG. 2 shows the structure of the nano-platelets formed by thermal deformation of the nano-lath precursor of example 7 according to the present invention, and it can be seen from the TEM photograph that the size of the crystal grains is between 45 and 150 nm.
The present application will now be illustrated and explained by means of several groups of specific examples and comparative examples, which should not be taken to limit the scope of the present application.
Example (b): examples 1 to 9 are stainless steels which were smelted according to the chemical composition range provided by the present invention, and the contents of C, cr, cu, W, and V elements were gradually increased, and the corresponding preparation processes were also appropriately adjusted within the technical parameters specified by the present invention. The size of the prepared bulk nanocrystalline metal material is 150 multiplied by 800 multiplied by 8mm.
Comparative example: the chemical compositions of C, cr, cu, W and V in comparative example 1 are all lower than the lower limit of the chemical composition range provided by the invention, and the chemical compositions of C, cr, cu, W and V in comparative example 9 are all higher than the upper limit of the chemical composition range provided by the invention, and the effect of the change of the chemical compositions of C, cr, cu, W and V on the preparation of the superplastic forming nanocrystalline antibacterial martensitic stainless steel is illustrated by comparing with example 1 and example 9 respectively. Comparative example 2, in which the amount of strain is below the lower limit of the amount of strain provided by the present invention, illustrates the effect of the amount of strain on the preparation of superplastic forming nanocrystalline, antibacterial martensitic stainless steel, by comparison with example 2. The strain rate of comparative example 3 is higher than the upper limit of the strain rate provided by the present invention, and the strain rate of comparative example 4 is lower than the lower limit of the strain rate provided by the present invention, and the effect of the strain rate on the preparation of the superplastic forming nanocrystalline antimicrobial martensitic stainless steel is illustrated by comparing with example 3 and example 4, respectively. Comparative example 5 slow cooling to room temperature after heat treatment illustrates the effect of cooling rate after heat treatment on the preparation of superplastic forming nanocrystalline, antibacterial martensitic stainless steel by comparison with example 5. The heat treatment temperature of comparative example 6, which is lower than the lower limit of the heat treatment temperature provided by the present invention, illustrates the effect of the heat treatment temperature on the preparation of the superplastic forming nanocrystalline antibacterial martensitic stainless steel by comparison with example 6. The heat distortion temperature of comparative example 7 is higher than the upper limit of the heat distortion temperature provided by the invention, and the heat distortion temperature of comparative example 8 is lower than the lower limit of the heat distortion temperature provided by the invention, and the influence of the heat distortion temperature on the preparation of the superplastic forming nanocrystalline antibacterial martensitic stainless steel is illustrated by comparing with example 7 and example 8 respectively. In addition, the invention also shows that the nanocrystalline antibacterial martensitic stainless steel provided by the invention has excellent hot forming performance, corrosion resistance, antibacterial performance and comprehensive mechanical properties by comparing with the 2Cr13 martensitic stainless steel and the antibacterial 2Cr13Cu3 martensitic stainless steel which are widely commercially used.
TABLE 1 chemical composition, heat treatment Process and Hot Rolling Process of example and comparative materials
From the results of table 2, it can be seen that the materials obtained in examples 1 to 9 are all nanocrystalline structures, which makes them have high strength, good plasticity and large hardness. In the chemical composition range specified by the invention, as the content of the chemical compositions of C, cr, cu, W and V is increased, the grain size of the material is gradually reduced, the strength and the hardness of the material are improved, and the elongation and the reduction of area are gradually reduced.
In comparative example 1, the contents of C, cr, cu, W and V elements are all lower than the lower limit of the chemical composition range specified in the present invention, ferrite structure is obtained after rapid cooling, and nanocrystalline structure is not obtained by thermal deformation with the precursor as the original structure. The contents of C, cr, cu, W and V elements in comparative example 9 were all higher than the chemical composition range specified in the present invention, and it obtained martensite + austenite + ferrite structure after rapid cooling, and also failed to obtain nanocrystalline structure after hot deformation.
The strain of comparative example 2 is small, and the structure of the nano-lath is still formed after deformation, so that the preparation of the nano-crystalline structure cannot be realized.
Comparative example 3 has a large strain rate and fails to realize the preparation of a nanocrystalline structure. Comparative example 4 has a small strain rate, and the grains are coarsened during thermal deformation, so that the preparation of the nanocrystalline structure cannot be achieved.
Comparative example 5 slowly cooled to room temperature after the heat treatment, and comparative example 6 had a low heat treatment temperature, which made their precursors non-nanoslabs structures as described in the present invention, and thus none of them could achieve the preparation of nanocrystalline structures.
The temperature ranges for hot deformation of the nano-lath precursors of comparative examples 7 and 8 are outside the range provided by the present invention, and the preparation of the nanocrystalline structure cannot be achieved.
Compared with 2Cr13 martensitic stainless steel and antibacterial 2Cr13Cu3 martensitic stainless steel which are widely and commercially applied at present, the novel nanocrystalline antibacterial martensitic stainless steel provided by the invention not only has higher strength and hardness, but also obviously improves the plasticity and toughness.
TABLE 2 texture characteristics and mechanical properties of the materials of the examples and comparative examples
As can be seen from the results in Table 3, examples 1 to 9 all had good hot formability, and both of them had high-temperature tensile elongations exceeding 300% in the hot forming temperature and strain rate ranges specified in the present invention, and superplastic forming was achieved. Please refer to fig. 3, which is a photograph of the stainless steel of example 7 after high temperature drawing. The high-temperature tensile elongation of comparative examples 1 to 9, 2Cr13 martensitic stainless steel and 2Cr13Cu3 antibacterial martensitic stainless steel are less than 100%, and their hot formability is far inferior to that of the examples of the present invention.
TABLE 3 thermoforming Properties of the example and comparative example materials
As can be seen from the results in table 4, the antibacterial ratios of examples 1 to 9 were all 90% or more, which indicates that the materials provided by the present invention have significant antibacterial functions. Within the range of the alloy components specified in the invention, the antibacterial effect of the material is more remarkable along with the increase of the Cu content. Please refer to fig. 4 for a photograph of the antibacterial effect of the stainless steel of example 7. The antibacterial rates of comparative examples 1 to 9 were all lower than those of examples 1 to 9. Under the preferable range of alloy components and the heat deformation condition, the antibacterial rate of the antibacterial martensitic stainless steel of the invention in the embodiments 5-7 is higher than that of 2Cr13Cu3 antibacterial martensitic stainless steel.
It can also be seen from the results of table 4 that the pitting potentials of examples 1 to 9 are higher than those of comparative examples 1 to 9, and also higher than that of 2Cr13Cu3 antibacterial martensitic stainless steel, which indicates that the corrosion resistance of the antibacterial martensitic stainless steel is also improved by the present invention. The pitting potentials of inventive examples 5-7 are comparable to 2Cr13 martensitic stainless steels in the preferred ranges of alloy composition and heat distortion conditions.
TABLE 4 antibacterial (Staphylococcus aureus) and Corrosion resistant Properties of the example and comparative example materials
| Material | Antibacterial ratio/%) | Pitting potential/mV |
| Example 1 | 90.5％ | 0.28 |
| Example 2 | 94.2％ | 0.30 |
| Example 3 | 96.9％ | 0.31 |
| Example 4 | 98.8％ | 0.33 |
| Example 5 | 99.4％ | 0.32 |
| Example 6 | 99.7％ | 0.33 |
| Example 7 | 99.9％ | 0.35 |
| Example 8 | 99.9％ | 0.34 |
| Example 9 | 99.9％ | 0.33 |
| Comparative example 1 | 80.3％ | 0.32 |
| Comparative example 2 | 90.3％ | 0.25 |
| Comparative example 3 | 93.8％ | 0.24 |
| Comparative example 4 | 89.5％ | 0.28 |
| Comparative example 5 | 93.5％ | 0.21 |
| Comparative example 6 | 92.1％ | 0.20 |
| Comparative example 7 | 99.3％ | 0.23 |
| Comparative example 8 | 99.5％ | 0.24 |
| Comparative example 9 | 99.7％ | 0.25 |
| 2Cr13 | No antibacterial property | 0.33 |
| 2Cr13Cu3 | 96.6％ | 0.22 |
1. Tissue characterization
The material was characterized using a Transmission Electron Microscope (TEM) and the grain size of the material was counted using a line cut. The preparation method of the TEM sample comprises the following steps: firstly, manually grinding and thinning a sample to be less than 40 mu m by using No. 2000 abrasive paper, and preparing the sample by using a punching machine
A sheet of (a); and then, thinning the sample by adopting a Tenupol-5 chemical double-spraying thinning instrument, wherein the double-spraying liquid is 6% perchloric acid, 30% butanol and 64% methanol, and the double-spraying thinning temperature is-25 ℃. And (3) observing the sample subjected to double-spraying thinning by using a TECNAI20 transmission electron microscope, wherein the working voltage during TEM observation is 200kV, and the alpha and beta angle rotation ranges are +/-30 degrees by using a double-inclined magnetic sample table. Drawing parallel fixed-length straight lines on the TEM picture, and calculating the grain size of the material according to the number of the fixed-length straight lines passing through the grains.
2. Tensile Property test
The room temperature and high temperature tensile properties of the comparative and example materials were tested using an Instron model 8872 tensile tester. Before testing, a lathe is adopted to process the material into standard tensile samples with the thread diameter of 10mm, the gauge length of 5mm and the gauge length of 30mm, three parallel samples are taken from each group of heat treatment samples, and the mechanical properties obtained by the experiment comprise tensile strength, yield strength and elongation.
3. Hardness test
The hardness of the materials of the examples and comparative examples were tested. The Vickers hardness of the material after 4h aging at 480 ℃ was measured using an HTV-1000 type durometer. Before testing, the sample surface was polished. The sample was a thin sheet having a size of 10mm in diameter and 2mm in thickness. The test loading force is 9.8N, the pressurizing duration is 15s, and the hardness value is automatically calculated by measuring the diagonal length of the indentation through computer hardness analysis software. The final hardness values were averaged over 15 points and three replicates were selected for each set of samples.
4. Test of antibacterial Property
The antibacterial performance of the material is tested according to GB/T16886.5-2003. Placing the sample to be tested into a 24-pore plate, and sucking 50 mu L10 by using a sterile gun head 6 cfu/mL of the bacterial suspension was added dropwise to the sample surface in each well, and the material was co-cultured with the bacteria. Ensuring that the environmental humidity of co-culture is above 90%, the temperature is constant at 37 ℃, taking out the sample together with the bacterial liquid on the sample after co-culture is carried out for 24h, putting the sample into a centrifuge tube, adding a proper PBS buffer solution to dilute the bacterial suspension, and fully oscillating vertex. Then sucking a proper volume of bacterial suspension, uniformly coating the bacterial suspension on a solid medium plate, culturing the bacterial suspension at the constant temperature of 37 ℃ for 24 hours, taking out the plate and counting colonies. The antibacterial rate was calculated according to the following formula:
wherein N is 1 The number of colonies in the control group; n is a radical of hydrogen 2 The number of colonies in the experimental group.
5. Test of Corrosion resistance
Processing the material to be measured into the size of
The cylindrical sample is connected with a copper wire, and the rest parts outside the working surface are sealed by epoxy resin, so that the wire is ensured not to be contacted with corrosive liquid. The test specimen was ground and polished, and the dynamic polarization curve of the material was tested using a Gamry electrochemical workstation using a 3.5% aqueous NaCl solution, thereby giving the pitting potential of the material.
The above description is only for the purpose of illustrating embodiments of the present application and is not intended to limit the scope of the present application, and all modifications of equivalent structures and equivalent processes, which are made by the contents of the specification and the drawings of the present application or are directly or indirectly applied to other related technical fields, are also included in the scope of the present application.
Claims (6)
1. A superplastic forming nanocrystalline antibacterial martensitic stainless steel is characterized in that: the stainless steel comprises the following chemical components in percentage by weight: c:0.16 to 0.32; cr:12.8 to 14.4; cu:1.4 to 3.0; w:1.2 to 2.8; v:0.04 to 0.20; la:0.01 to 0.03; mn is less than 0.15; n is less than 0.03; the balance being Fe;
smelting by adopting a vacuum induction furnace to obtain a raw material ingot; after the cast ingot is polished, the cast ingot is processed into a blank through cogging forging and finish forging at the temperature of more than 1100 ℃;
after preserving the temperature of the blank obtained by the finish forging processing at a high temperature for a period of time, rapidly cooling the blank to room temperature to obtain a nano lath precursor; thermally deforming the obtained nano-lath precursor to obtain an equiaxed nano-crystalline structure; for the material with equiaxed nanocrystalline structure, the temperature is 760 to 840 ℃, and the strain rate is 0.001 to 0.02s -1 Carrying out superplastic forming under the condition of (1); after superplastic forming, aging for 3-5 h at 460-500 ℃ to finally obtain the nanocrystalline antibacterial martensitic stainless steel.
2. The superplastically formed nanocrystalline, antibacterial martensitic stainless steel as claimed in claim 1, wherein: c: 0.24-0.28; cr:13.6 to 14.0; cu:2.2 to 2.6; w:2.0 to 2.4; v:0.12 to 0.16; la:0.01 to 0.03; mn is less than 0.15; n is less than 0.03; the balance being Fe.
3. The superplastically formed nanocrystalline, antibacterial martensitic stainless steel as claimed in claim 1, wherein: keeping the temperature of the blank obtained by the finish forging processing at 980-1060 ℃, wherein the heat preservation time t = (1-2) D min, wherein D is the effective thickness of the sample, and the unit is mm; and (3) quickly cooling to room temperature after heat preservation, controlling the cooling rate to be between 2 and 20 ℃/s, and cooling to obtain the nano-strip precursor.
4. The superplastically formed nanocrystalline, antibacterial martensitic stainless steel as claimed in claim 1, wherein: the nano lath precursor has the temperature of 820-900 ℃ and the strain rate of 0.1-1.0 s -1 Carrying out thermal deformation under the condition of (1), wherein the total strain amount is more than or equal to 70 percent, and obtaining an equiaxed nanocrystalline structure after thermal deformation.
5. The superplastically formed nanocrystalline, antibacterial martensitic stainless steel according to claim 1 or 4, characterized in that: the heat distortion temperature is 860 to 880 ℃, and the strain rate is 0.2 to 0.5s -1 The total strain amount is 90% or more.
6. The superplastically formed nanocrystalline, antibacterial martensitic stainless steel as claimed in claim 5, wherein: the microstructure of the prepared material is nanocrystalline, and the grain size is between 40 and 150 nm; the tensile strength of the material is 1660-1820 MPa, the elongation is 12-16%, the reduction of area is more than 40%, the antibacterial rate to staphylococcus aureus is more than 99%, and the pitting potential is higher than 0.3mV.
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| JPH03215625A (en) * | 1990-01-18 | 1991-09-20 | Sumitomo Metal Ind Ltd | Production of superplastic duplex stainless steel and hot working method therefor |
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| CN112251685B (en) * | 2020-09-29 | 2022-05-31 | 中国科学院金属研究所 | Ultrahigh-strength nanocrystalline 12Cr13Cu4Mo stainless steel and preparation method thereof |
| CN112251682B (en) * | 2020-09-29 | 2022-03-18 | 中国科学院金属研究所 | Ultrahigh-strength nanocrystalline 20Cr13W3Co2 stainless steel and preparation method thereof |
| CN112410674A (en) * | 2020-11-20 | 2021-02-26 | 内蒙古科技大学 | Rare earth-containing copper-rich precipitated phase reinforced martensitic stainless steel and preparation method thereof |
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2021
- 2021-04-21 CN CN202110431500.0A patent/CN113174544B/en active Active
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