Copper-containing martensite antibacterial stainless steel and manufacturing method thereof

Abstract

The invention discloses martensite antibacterial stainless steel and a preparation method thereof, and the martensite antibacterial stainless steel comprises the following components in percentage by weight: 0.3-0.5% of C; si < = 0.5%; mn < = 0.5%; p is less than or equal to 0.04%; s is less than or equal to 0.01%; 13.0% to 15.0% of Cr; mo < = 1.0%; v < = 0.2%; 0.2 to 0.4 percent of Al; 0.1 to 0.2 percent of N; 3.0 to 5.0 percent of Cu; the elements satisfy the following quantitative relationship: (Cr + 3.3 * Mo) / Cu < = 4.0; the balance is iron and trace impurities inevitably introduced in the production process. The martensite antibacterial stainless steel prepared according to the formula and the technology has the following performance characteristics that the hardness (HRC) is 62, the antibacterial rate is 99.9%, the corrosion resistance is 70 mv, and the surface subjected to hot rolling machining is free of defects.

Description

Technical Field

[0001] This invention relates to the field of stainless steel materials technology, specifically to a copper-containing martensitic antibacterial stainless steel and its manufacturing method. Background Technology

[0002] As people's living standards continue to improve, public concern for health and hygiene is growing. Various viruses have ravaged the globe, causing immense harm to human health and economic development. These events have spurred a growing demand for antibacterial products, thus promoting the research and application of antibacterial stainless steel. Antibacterial stainless steel is made by adding antibacterial metallic elements (such as copper and silver) to conventional stainless steel, followed by special heat treatment, resulting in an alloy with excellent antibacterial properties. Antibacterial stainless steel possesses both excellent broad-spectrum antibacterial properties and good mechanical and corrosion resistance, making it a promising candidate for various applications. Copper-containing antibacterial stainless steel, in particular, has a lower cost and is easier to market.

[0003] The prior art has been disclosed as follows: CN101323930A discloses antibacterial martensitic stainless steel and its application in the hardware industry. The study investigates stainless steel materials, the antibacterial properties of copper, and how to incorporate copper into stainless steel materials. By adding an appropriate amount of copper to martensitic stainless steel and undergoing a special heat treatment (high-temperature tempering to obtain a better microstructure, resulting in higher strength, good toughness, corrosion resistance, and good antibacterial properties), ε-Cu phase is dispersed and precipitated in the stainless steel, and copper ions dissolve in water, thus exhibiting excellent antibacterial properties. The addition of copper refines the stainless steel grains, resulting in higher strength and hardness, and reducing the passivation range, but slightly increases the corrosion rate. The antibacterial martensitic stainless steel exhibits an antibacterial effect of over 99% against Staphylococcus aureus and 97% against Escherichia coli, not only improving the performance of stainless steel materials but also effectively inhibiting bacterial growth. Antibacterial martensitic stainless steel is mainly used in hardware products.

[0004] CN114000066A discloses an antibacterial and antiviral copper-containing stainless steel, its preparation, and its application. This invention provides an antibacterial and antiviral copper-containing stainless steel, a method for preparing stainless steel conforming to its composition, and its application. The copper-containing stainless steel comprises a stainless steel matrix and a copper-rich phase uniformly distributed within the stainless steel matrix, wherein the copper content of the copper-containing stainless steel is 6-30 wt%. The preparation method includes powder metallurgy or optimized casting technology without copper embrittlement issues. Compared to traditional copper-containing antibacterial stainless steel, the copper-containing stainless steel product of this invention contains a sufficient amount of copper-rich precipitates, which not only achieves good bactericidal effects but also achieves virus-killing capabilities comparable to pure copper. It can be used to prepare the entire or all of components such as knives, elevator buttons, railings, handrails, door handles, and cups, effectively killing bacteria and viruses present on their surfaces.

[0005] In summary, Previously, copper-containing martensitic antibacterial stainless steels had a wide range of copper content, generally between 1% and 5%. Lower copper content did not yield excellent antibacterial properties, while higher copper content significantly reduced the alloy's hot workability, causing defects such as surface cracks, reducing hot workability, affecting surface quality, and increasing production costs. Therefore, it is necessary to add some beneficial elements to improve the alloy's hot workability.

[0006] In order to solve the problems in the existing technology, there is an urgent need to provide a copper-containing martensitic antibacterial stainless steel and its manufacturing method.

[0007] This patent invention discloses a copper-containing martensitic antibacterial stainless steel. By optimizing the appropriate ratio of chromium, molybdenum and copper elements, the alloy is guaranteed to have excellent and long-lasting antibacterial properties. An appropriate amount of aluminum is also added to avoid the generation of hot working cracks, thereby ensuring that the alloy has excellent surface quality. Summary of the Invention

[0008] The purpose of this invention is to provide a copper-containing martensitic antibacterial stainless steel. Through the combination of formulation and process, the optimal ratio of chromium, molybdenum and copper elements is used to ensure that the alloy has excellent and long-lasting antibacterial properties. An appropriate amount of aluminum element is also added to avoid the generation of hot working cracks and thus ensure that the alloy has excellent surface quality.

[0009] To achieve the above objectives, the following technical solutions are used: A martensitic antibacterial stainless steel comprising the following components in weight percentage: C 0.3-0.5%; Si≤0.5%; Mn≤0.5%; P≤0.04%; S≤0.01%; Cr 13.0-15.0%; Mo≤1.0%; V≤0.2%; Al 0.2-0.4%; N 0.1-0.2%; Cu 3.0-5.0%; Furthermore, the above elements satisfy the following quantitative relationship: (Cr + 3.3 × Mo) / Cu ≤ 4.0; The balance consists of iron and trace impurities that are unavoidably introduced during the production process.

[0010] As a further improvement to this solution, the trace impurities originate from the raw materials and environmental contact during the smelting and processing stages, and their total content is ≤0.1%, with the content of a single impurity element being ≤0.01%.

[0011] As a further improvement to this scheme, the following quantitative relationship is satisfied: 3.0≤(Cr+3.3×Mo) / Cu≤4.0.

[0012] As a further improvement to this scheme, the Al content satisfies the following quantitative relationship: 0.25% ≤ Al ≤ 0.35%. A processing method for preparing the martensitic antibacterial stainless steel, characterized by comprising the following steps: S1 steelmaking and casting; S2 hot-rolled; S3 antibacterial heat treatment process; S4 quenching process.

[0013] As a further improvement to this solution, the detailed steps of S1 and S2 are as follows: S1 Steelmaking and Casting: Steel is produced using an electric furnace-AOD furnace-LF furnace with the above chemical composition, and then continuously cast into billets. During continuous casting, the molten steel is protected by argon gas. The billets are slowly cooled to room temperature and then the surface is ground.

[0014] In this step, the use of argon gas for protection helps prevent the aluminum from oxidizing and forming harmful inclusions. S2 hot rolled: The alloy heating temperature is 1150-1200℃, the holding time is more than 2 hours, the initial hot rolling temperature is 1150-1200℃, multi-pass rolling is adopted, the thinning amount of each pass is less than 30% to avoid crack defects, the final rolling temperature is 900-950℃, rapid water cooling is performed, and the coiling temperature is 600-700℃. As a further improvement to this solution, the detailed steps of S3 and S4 are as follows: S3 antibacterial heat treatment process: A bell-type annealing furnace with argon protection can be used to slowly heat the alloy to a temperature of 750-800℃ and hold it for more than 6 hours. The average size of the antibacterial phase is 5-10μm, ensuring excellent antibacterial performance. After slow cooling to room temperature, the alloy can be processed by pickling, cold rolling and annealing.

[0015] S4 quenching process: A continuous annealing furnace is used, with a quenching temperature of 1050-1100℃ and a holding time of 4-6 minutes to ensure that the antibacterial properties are not lost. Then, the product is pickled, cleaned, and dried.

[0016] As a further improvement to this solution, the surface of the billet is peeled before hot rolling, with a peeling thickness of about 1-3 mm.

[0017] As a further improvement to this scheme, water-soluble rolling oil is used for lubrication during hot rolling, with a rolling oil concentration of 6-8%.

[0018] As a further improvement to this method, the antibacterial heat treatment is carried out in an argon protective atmosphere with an argon purity of ≥99%. As a further improvement to this scheme, the alloy is pretreated by pickling after quenching using a nitric acid and water mixture with a volume ratio of 1:3, at a temperature of 50-60℃, for 4-6 minutes, followed by rinsing with cold water and drying.

[0019] It has the following beneficial effects: 1. The chemical composition and the role of the main chemical elements in this invention Carbon: It is the main element that ensures the hardness of the alloy. If the amount is too low, the hardness of the alloy cannot be guaranteed. If the amount is too high, the corrosion resistance of the alloy will be reduced. It is more reasonable to control it at 0.3-0.5%.

[0020] Silicon: This is mainly because it has a good deoxidizing effect, but too much of it will reduce the cold working plasticity of steel. It is more reasonable to control it below 0.5%.

[0021] Manganese: Considering that manganese can improve the hot working properties of alloys, but too much manganese will reduce the corrosion resistance of alloys, it is more reasonable to control it below 0.5%.

[0022] Phosphorus and sulfur: Considering the hot working performance and corrosion resistance of the alloy, these two elements should be kept as low as possible, and should be controlled at P≤0.04% and S≤0.01%.

[0023] Chromium: It is an important element to ensure the corrosion resistance of the alloy. A high content will increase the cost of the alloy and affect the antibacterial properties. It is more reasonable to control it at 13.0-15.0%.

[0024] Molybdenum: It is an element that improves the corrosion resistance of alloys. A higher content will increase the cost of the alloy and affect its antibacterial properties. It is more reasonable to control it to ≤1.0%.

[0025] Vanadium: It is an element that refines the microstructure and improves toughness. However, a high content will reduce hardness. It is more reasonable to control it to ≤0.2%.

[0026] Copper is an important element for ensuring the antibacterial properties of alloys. A higher content will increase the cost of alloys and the difficulty of hot processing and manufacturing. It is more reasonable to control it at 3-5%.

[0027] Aluminum: It can improve the hot workability of alloys and prevent cracking defects during hot working. Without aluminum, copper-rich phase particles are prone to oxidation at high temperatures. Oxidized copper-rich phase particles tend to aggregate at the grain boundaries of the matrix. The low melting point of copper-rich phase particles significantly reduces grain boundary bonding, thus significantly reducing the alloy's thermoplasticity and making it susceptible to cracking defects during hot working. With the addition of aluminum, aluminum preferentially oxidizes at high temperatures, forming a protective film on the alloy surface to prevent oxidation of copper-rich phase particles. Unoxidized copper-rich phase particles gradually dissolve and dissipate at high temperatures, significantly improving the alloy's thermoplasticity. This, in turn, avoids cracking defects during hot working, improves the alloy's surface quality and yield, and meets the manufacturability requirements for stable mass production. However, a high aluminum content increases the difficulty of smelting and manufacturing, and can easily lead to excessive inclusions. Controlling the aluminum content to 0.2-0.4% is more reasonable.

[0028] Nitrogen: It can increase the hardness of alloys and improve corrosion resistance, but higher levels will increase the difficulty of steelmaking. It is more reasonable to control it below 0.1-0.2%.

[0029] Specifically: Chemical composition (weight percentage): The elements satisfy the following quantitative relationship: (Cr + 3.3 × Mo) / Cu ≤ 4.0.

[0030] In the above composition, the ratio of chromium, molybdenum, and copper must satisfy (chromium + 3.3 × molybdenum) / copper ≤ 4.0. This is primarily to ensure the alloy possesses excellent antibacterial properties. When this ratio is not met, the alloy's antibacterial properties significantly decrease, failing to meet antibacterial alloy standards. Furthermore, the rate of antibacterial performance degradation accelerates during user operation, failing to meet the requirements for durable antibacterial performance. Increasing the chromium and molybdenum content results in a denser passivation film on the alloy surface, improving corrosion resistance. However, this also reduces copper ion precipitation in the substrate, lowering antibacterial performance. Therefore, it is necessary to increase the copper content to ensure a stable amount of copper ion precipitation, thereby maintaining stable antibacterial performance. Controlling (chromium + 3.3 × molybdenum) / copper ≤ 4.0 ensures both no loss of corrosion resistance and excellent, durable antibacterial properties.

[0031] 2. Manufacturing method and key processes of the present invention The alloy of this invention adopts a low-temperature hot rolling process. The initial hot rolling temperature is lower than that of conventional martensitic stainless steel, which is 1150-1200℃. The final rolling temperature is also lower than that of conventional martensitic stainless steel, which is 900-950℃. This is to avoid defects such as surface cracks in the alloy during the hot rolling process.

[0032] The alloy of this invention is produced using a high-temperature, short-time quenching process, with a quenching temperature of 1050-1100℃ and a holding time of 4-6 minutes. This is to obtain good hardness while ensuring that the antibacterial properties are not compromised.

[0033] 3. The martensitic antibacterial stainless steel prepared by the formula and process of the present invention has the following performance characteristics. The final performance test results are: hardness (HRC) 62, antibacterial rate 99.9%, corrosion resistance 70mv, and no defects on the hot-rolled surface. Attached Figure Description

[0034] Figure 1 Microstructure diagram of the metallographic structure after quenching in Example 1 of this invention. Detailed Implementation

[0035] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described below in conjunction with embodiments and accompanying drawings: A martensitic antibacterial stainless steel comprising the following components in weight percentage: C 0.3-0.5%; Si≤0.5%; Mn≤0.5%; P≤0.04%; S≤0.01%; Cr 13.0-15.0%; Mo≤1.0%; V≤0.2%; Al 0.2-0.4%; N 0.1-0.2%; Cu 3.0-5.0%; Furthermore, the above elements satisfy the following quantitative relationship: (Cr + 3.3 × Mo) / Cu ≤ 4.0; The balance consists of iron and trace impurities that are unavoidably introduced during the production process.

[0036] Example 1 A copper-containing martensitic antibacterial stainless steel, comprising, by weight percentage, the following chemical composition: Carbon 0.34%, Silicon 0.17%, Manganese 0.12%, Phosphorus 0.030%, Sulfur 0.001%, Chromium 13.3%, Copper 3.4%, Aluminum 0.25%, Nitrogen 0.13%, (Chromium + 3.3 × Molybdenum) / Copper 3.9; The balance consists of iron and trace impurities that are unavoidably introduced during the production process. These trace impurities originate from raw materials and environmental contact during smelting and processing, and their total content is ≤0.1%, with the content of a single impurity element being ≤0.01%.

[0037] A method for processing copper-containing martensitic antibacterial stainless steel, the main process includes the following steps: Steelmaking and casting process: Steel is made using an electric furnace-AOD furnace-LF furnace according to the above chemical composition, and continuously cast into steel billets with a thickness of 200mm and a width of 1200mm. Argon gas is used to protect the molten steel during continuous casting to avoid the oxidation of aluminum elements and the formation of harmful inclusions. The billets are slowly cooled to room temperature and then the surface is ground 2mm.

[0038] Hot rolling process: The alloy heating temperature is 1190℃, the holding time is 2.5 hours, the initial hot rolling temperature is 1190℃, and the rolling process is carried out by 7 passes of rough rolling and 7 passes of finish rolling. The thinning amount of each pass is less than 30% to avoid crack defects. The final rolling temperature is 940℃, rolled to 3mm thickness, rapidly water cooled, and the coiling temperature is 650℃.

[0039] Antibacterial heat treatment process: A bell-type annealing furnace with argon protection can be used to slowly heat the alloy to 780℃ and hold it for 7 hours to ensure excellent antibacterial properties, and then slowly cool it to room temperature.

[0040] Quenching process: A continuous annealing furnace can be used, with a quenching temperature of 1050℃ and a holding time of 6 minutes to ensure that the antibacterial properties are not lost. Then pickle, clean, and dry.

[0041] like Figure 1 The image shown is a microstructure of the metallographic structure after quenching in Example 1. The white granular material is a copper-rich precipitate, i.e., an antibacterial phase.

[0042] Example 2 A copper-containing martensitic antibacterial stainless steel, comprising, by weight percentage, the following chemical composition: Carbon 0.42%, Silicon 0.15%, Manganese 0.14%, Phosphorus 0.035%, Sulfur 0.001%, Chromium 14.5%, Copper 4.3%, Aluminum 0.30%, Nitrogen 0.12%, (Chromium + 3.3 × Molybdenum) / Copper 3.4; The balance consists of iron and trace impurities that are unavoidably introduced during the production process. These trace impurities originate from raw materials and environmental contact during smelting and processing, and their total content is ≤0.1%, with the content of a single impurity element being ≤0.01%.

[0043] A method for processing copper-containing martensitic antibacterial stainless steel, the main process includes the following steps: Steelmaking and casting process: Steel is made using an electric furnace-AOD furnace-LF furnace according to the above chemical composition, and continuously cast into steel billets with a thickness of 200mm and a width of 1200mm. Argon gas is used to protect the molten steel during continuous casting to avoid the oxidation of aluminum elements and the formation of harmful inclusions. The billets are slowly cooled to room temperature and then the surface is ground 2mm.

[0044] Hot rolling process: The alloy heating temperature is 1180℃, the holding time is 3 hours, the initial hot rolling temperature is 1180℃, and the rolling process is carried out by 7 passes of rough rolling and 7 passes of finish rolling. The thinning amount of each pass is less than 30% to avoid crack defects. The final rolling temperature is 930℃, rolled to 3mm thickness, and then rapidly water-cooled. The coiling temperature is 660℃.

[0045] Antibacterial heat treatment process: A bell-type annealing furnace with argon protection can be used to slowly heat the alloy to 770℃ and hold it for 8 hours to ensure excellent antibacterial properties, and then slowly cool it to room temperature.

[0046] Quenching process: A continuous annealing furnace can be used, with a quenching temperature of 1080℃ and a holding time of 5 minutes to ensure that the antibacterial properties are not lost. Then pickle, clean, and dry.

[0047] Example 3 A copper-containing martensitic antibacterial stainless steel, comprising, by weight percentage, the following chemical composition: Carbon 0.48%, Silicon 0.18%, Manganese 0.15%, Phosphorus 0.031%, Sulfur 0.001%, Chromium 14.4%, Molybdenum 0.5%, Vanadium 0.12%, Copper 4.6%, Aluminum 0.34%, Nitrogen 0.16%, (Chromium + 3.3 × Molybdenum) / Copper 3.5; The balance consists of iron and trace impurities that are unavoidably introduced during the production process. These trace impurities originate from raw materials and environmental contact during smelting and processing, and their total content is ≤0.1%, with the content of a single impurity element being ≤0.01%.

[0048] A method for processing copper-containing martensitic antibacterial stainless steel, the main process includes the following steps: Steelmaking and casting process: Steel is made using an electric furnace-AOD furnace-LF furnace according to the above chemical composition, and continuously cast into steel billets with a thickness of 200mm and a width of 1200mm. Argon gas is used to protect the molten steel during continuous casting to avoid the oxidation of aluminum elements and the formation of harmful inclusions. The billets are slowly cooled to room temperature and then the surface is ground 2mm.

[0049] Hot rolling process: The alloy heating temperature is 1160℃, the holding time is 3 hours, the initial hot rolling temperature is 1160℃, and the rolling process is carried out by 7 passes of rough rolling and 7 passes of finish rolling. The thinning amount of each pass is less than 30% to avoid crack defects. The final rolling temperature is 920℃, rolled to 3mm thickness, and then rapidly water-cooled. The coiling temperature is 670℃.

[0050] Antibacterial heat treatment process: A bell-type annealing furnace with argon protection can be used to slowly heat the alloy to 790℃ and hold it for 6 hours to ensure excellent antibacterial properties, and then slowly cool it to room temperature.

[0051] Quenching process: A continuous annealing furnace can be used, with a quenching temperature of 1100℃ and a holding time of 4 minutes to ensure that the antibacterial properties are not lost. Then pickle, clean, and dry.

[0052] Comparative Example 1 The difference between this comparative example and Example 3 is that: The weight percentage of aluminum (Al) in the chemical composition is 0.14%, which is below the limit range of 0.2-0.4%. The weight percentages of the remaining elements (carbon 0.48%, silicon 0.18%, manganese 0.15%, phosphorus 0.031%, sulfur 0.001%, chromium 14.4%, molybdenum 0.5%, vanadium 0.12%, copper 4.6%, nitrogen 0.16%, (chromium + 3.3 × molybdenum) / copper 3.5) and the processing technology (including parameters of each step such as smelting, hot rolling, antibacterial heat treatment, quenching treatment, and pretreatment and post-treatment processes) are the same as in Example 3.

[0053] Comparative Example 2 The difference between this comparative example and Example 3 is that... The chemical composition contains 0.8% molybdenum (Mo) by weight and 3.6% copper (Cu) by weight, resulting in a (chromium + 3.3 × molybdenum) / copper value of 4.7, which is higher than the limit range of 4.0. The weight percentages of the remaining elements (carbon 0.48%, silicon 0.18%, manganese 0.15%, phosphorus 0.031%, sulfur 0.001%, chromium 14.4%, vanadium 0.12%, aluminum 0.34%, nitrogen 0.16%) and the processing technology (including parameters for each step of smelting, hot rolling, antibacterial heat treatment, quenching treatment, and pretreatment and post-treatment processes) are the same as in Example 3.

[0054] Comparative Example 3 The difference between this comparative example and Example 3 is that... The chemical composition contains 14.8% chromium (Cr) and 3.9% copper (Cu) by weight, resulting in a (chromium + 3.3 × molybdenum) / copper value of 4.2, which is higher than the limit range of 4.0. The weight percentages of the remaining elements (carbon 0.48%, silicon 0.18%, manganese 0.15%, phosphorus 0.031%, sulfur 0.001%, molybdenum 0.5%, vanadium 0.12%, aluminum 0.34%, nitrogen 0.16%) and the processing technology (including parameters for each step of smelting, hot rolling, antibacterial heat treatment, quenching treatment, and pretreatment and post-treatment processes) are the same as in Example 3.

[0055] Comparison example: Use conventional 40Cr13 martensitic stainless steel.

[0056] Examples 1-3, Comparative Examples 1-3, and the comparative examples were tested according to the following test standards: The antibacterial properties of the alloy tested in this invention were tested according to the standard JIS Z2801-2000 "Antibacterial Processed Products - Test Methods for Antibacterial Properties and Antibacterial Effects". A conventional martensitic stainless steel without Cu was used as a control sample for comparative testing. The main test procedures are as follows: 1. Test strains: Escherichia coli (SIM B282) Staphylococcus aureus (SIM B283) 2. Detection method: Cut the sample into 50×50mm pieces and sterilize them (three copies).

[0057] Add several milliliters of bacterial solution to the sample to maintain the colony count at 10⁵.

[0058] Cover the sample surface with a plastic film, then place it in a sterile petri dish and incubate it in a constant temperature incubator at 36±1℃ for 24 hours before counting the viable bacteria.

[0059] Repeat the above steps for the control sample.

[0060] 3. Antibacterial rate calculation: Antibacterial rate = [(AB) / A] × 100% Where: A - average viable count of control samples after 24 hours, B - average viable count of antibacterial samples after 24 hours.

[0061] The hardness of the tested alloy products was tested according to the national standard: Rockwell Hardness Test for Metallic Materials GB / T230.1-2018; the corrosion resistance was tested according to the national standard: Potentiodynamic Measurement Method for Pitting Potential of Stainless Steel in Sodium Chloride Solution GB / T 17897-2023.

[0062] The results of testing the hardness, antibacterial properties, corrosion resistance, and surface quality of the experimental alloy are shown in Table 1. Note: The performance of italicized and bold text does not meet the requirements of this patent.

[0063] Comparison of test results from Example 3 and Comparative Examples 2 and 3: In this technical solution, the ratio of chromium, molybdenum, and copper must meet the requirement of (chromium + 3.3 × molybdenum) / copper ≤ 4.0. The main purpose is to ensure both the alloy's corrosion resistance is not compromised and its antibacterial properties are excellent and durable. When the ratio of these three elements does not meet the design requirements, the alloy's antibacterial properties significantly decrease, failing to meet the standards for antibacterial alloys. Furthermore, during user operation, the rate of decline in antibacterial properties will significantly accelerate, failing to meet the requirements for durable antibacterial performance.

[0064] Furthermore, the difference in antibacterial properties mainly stems from the synergistic effect of key elements. Copper (Cu) is the core element for enhancing antibacterial properties, and its content range and ratio with chromium (Cr) and molybdenum (Mo) directly affect the antibacterial properties and durability of the alloy in the service environment. Comparison of test results from Example 3 and Comparative Example 1: Adding appropriate amounts of aluminum can improve the hot working properties of the alloy, prevent the over-oxidation of copper-rich phase particles during hot working, thereby avoiding hot working crack defects, improving the surface quality and yield of the alloy, and meeting the manufacturability requirements for stable mass production.

[0065] The proper proportion of aluminum (Al) can suppress the high-temperature oxidation behavior of copper-rich phase particles, avoid the generation of hot-rolled crack defects, and thus ensure the excellent surface quality of the alloy. Nitrogen (N) is a beneficial element, and its content range supports the improvement of mechanical properties and corrosion resistance.

[0066] The hot rolling temperature in the processing is lower than that of conventional martensitic stainless steel to avoid defects such as surface cracks during the hot rolling process. The quenching process, combined with the component proportions, is used to achieve good hardness and maintain the alloy's excellent antibacterial properties.

[0067] Based on extensive experiments, a copper-containing martensitic antibacterial stainless steel was selected, which can ensure that the material has excellent comprehensive performance (antibacterial properties) while also having good surface quality.

[0068] The above description is only a preferred embodiment of the present invention and does not limit the patent scope of the present invention. All equivalent modifications made using the present invention are within the patent protection scope of the present invention.

Claims

1. A martensitic antibacterial stainless steel, characterized in that, Includes the following components by weight percentage, C 0.3-0.5%； Si≤0.5%; Mn≤0.5%; P≤0.04%； S≤0.01%； Cr 13.0-15.0%； Mo≤1.0%; V≤0.2%； Al 0.2-0.4%； N 0.1-0.2%； Cu 3.0-5.0%; Furthermore, the above elements satisfy the following quantitative relationship: (Cr + 3.3 × Mo) / Cu ≤ 4.0; The balance consists of iron and trace impurities that are unavoidably introduced during the production process.

2. The martensitic antibacterial stainless steel according to claim 1, characterized in that, The trace impurities originate from the raw materials and environmental contact during smelting and processing, and their total content is ≤0.1%, with the content of a single impurity element being ≤0.01%.

3. The martensitic antibacterial stainless steel according to claim 1, characterized in that, The following quantitative relationship must be satisfied: 3.0≤(Cr+3.3×Mo) / Cu≤4.

0.

4. The martensitic antibacterial stainless steel according to claim 1, characterized in that, The Al content satisfies the following quantitative relationship: 0.25% ≤ Al ≤ 0.35%.

5. A processing method for preparing the martensitic antibacterial stainless steel according to any one of claims 1-4, characterized in that, Includes the following steps: S1 steelmaking and casting; S2 hot-rolled; S3 antibacterial heat treatment process; S4 quenching process.

6. The processing method of martensitic antibacterial stainless steel according to claim 4, characterized in that, The detailed steps for S1 and S2 are as follows: S1 Steelmaking and Casting: Steelmaking is carried out using an electric furnace-AOD furnace-LF furnace according to the above chemical composition, and the steel billet is continuously cast. During continuous casting, the molten steel is protected by argon gas. The billet is slowly cooled to room temperature and then the surface is ground. S2 hot rolled: The alloy is heated to 1150-1200℃, held for more than 2 hours, and the initial hot rolling temperature is 1150-1200℃. It is rolled in multiple passes, with a thinning amount of less than 30% per pass. The final rolling temperature is 900-950℃, followed by rapid water cooling and a coiling temperature of 600-700℃.

7. The processing method of martensitic antibacterial stainless steel according to claim 4, characterized in that, The detailed steps for S3 and S4 are as follows: S3 antibacterial heat treatment process: A bell-type annealing furnace with argon protection can be used to slowly heat the alloy to a temperature of 750-800℃ and hold it for more than 6 hours. The average size of the antibacterial phase is 5-10μm, ensuring excellent antibacterial performance. After slow cooling to room temperature, the alloy can be pickled, cold rolled and annealed after heat treatment. S4 quenching process: A continuous annealing furnace is used, with a quenching temperature of 1050-1100℃ and a holding time of 4-6 minutes to ensure that the antibacterial properties are not lost. Then, the product is pickled, cleaned, and dried.

8. The processing method of martensitic antibacterial stainless steel according to claim 4, characterized in that, Before hot rolling, the surface of the billet is peeled off, with a peeling thickness of about 1-3 mm.

9. The processing method of martensitic antibacterial stainless steel according to claim 4, characterized in that, Water-soluble rolling oil is used for lubrication during hot rolling, with a concentration of 6-8%.

10. The processing method of martensitic antibacterial stainless steel according to claim 4, characterized in that, After quenching, the alloy is pretreated by pickling with a nitric acid and water mixture with a volume ratio of 1:3, at a temperature of 50-60℃ for 4-6 minutes. After pickling, it is rinsed with cold water and dried.

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