Household knife and preparation method thereof

Abstract

The invention discloses a household knife and a preparation method thereof. A high entropy alloy doped with Zn and rare earth elements is adopted, and a blade material having both hardness and toughness and antibacterial safety is obtained by utilizing powder rolling and annealing technology. The blade material is combined with a double trapezoidal knife structure to greatly improve the sharpness and durability of the knife. The blade material has the advantages of simple process and suitability for mass production, and is very suitable for application in household knives.

Description

Technical Field

[0001] The invention relates to a knife and a preparation method thereof, in particular to a household knife and a preparation method thereof, and belongs to the technical field of knifes. Background Art

[0002] As the saying goes, if you want to do your work well, you must first sharpen your tools. The same is true for home life and cooking delicious meals. A good knife can not only test the chef's knife skills and improve the overall cooking efficiency, but also increase the happiness of cooking and improve the quality of life. A good knife should have the performance characteristics of high sharpness, durability, rust resistance, and health and safety. These performances are mainly determined by three points: the material of the knife, the craftsmanship of the knife, and the structure of the knife. Many universities, research institutes, and companies at home and abroad have conducted extensive research on these three aspects.

[0003] Tool materials: Tool materials in developed countries such as Europe, America and Japan are mainly high-carbon and high-chromium stainless steels such as X50CrMoV15, M390 and VG10, which have high hardness and can reach more than 55HRC after heat treatment. They are very sharp, but the heat treatment process is complicated, the toughness is poor and the tool is easy to break. Commonly used stainless steels for knives in my country include 2Cr13, 3Cr13, 4Cr13, etc. On this basis, Patent Document 1 (CN104278199A) discloses a martensitic stainless steel with high hardness, strong antibacterial properties and excellent corrosion resistance and a heat treatment method thereof. The chemical composition of the stainless steel is as follows (weight %): C: 0.28-0.35; Si: ≤1.00; Mn: ≤1.00; P: ≤0.040; S: ≤0.030; Cr: 12.00-14.00; Cu: 2.5-3.5; Mo: 0.5-1.0; N: 0.02-0.08; the remainder is Fe; after special heat treatment, the stainless steel can evenly and dispersely precipitate a copper-rich phase in the stainless steel matrix, thereby giving the stainless steel antibacterial function while still maintaining the high hardness of the martensitic stainless steel. The heat treatment process of this method is still very complicated and does not help to improve toughness.

[0004] Preparation process. There are two commonly used process methods: 1) Forging or stamping of a single material. Most imported knives are forged by hand. For example, each knife produced by Germany's Trident is cut from a whole piece of steel, and then carefully forged and sharpened through multiple manual processes. Due to the low efficiency and high cost of forging, stamping is currently the main method used to produce kitchen knives in China, but there are large differences in performance such as sharpness. 2) Composite steel is used, ordinary stainless steel is used for the blade, and high-carbon and high-chromium stainless steel such as X50CrMoV15, VG10, and M390 are selected for the blade, which is made through composite technology. The French TB Group has successfully produced laser-clad knives using laser cladding processing technology, and the blade cladding part uses powder materials with special properties. Patent document 2 (CN108311854A) discloses a process for preparing a wear-resistant kitchen knife, which uses 45# steel, high carbon steel or stainless steel billet as the blade material, uses plasma spray welding technology to prepare a layer of WC particle reinforced Fe-based composite coating on the surface of the billet, and then uses wire cutting technology to process the billet into pieces of 2mm thick rectangular thin sheets, where the coated part of the thin sheet is used as the blade. These methods have cumbersome procedures, high technical difficulty, low efficiency, and the combination of laser cladding or plasma spray welding has poor bonding strength. The coating is easy to fall off during the use of the kitchen knife, posing a safety hazard.

[0005] In terms of structural design. Foreign companies have studied and formulated design criteria for the structural dimensions of knives in detail. Patent document 3 (CN102554945A) has developed a kitchen knife with a blade and a handle, in which the blade is grinded on both sides to form a cutting edge and the blade forms a sharp cutting angle. The difference between the maximum and minimum cutting angles is at least 8 degrees. Here, in the area near the handle, the cutting angle can be 15 to 35 degrees, and in the area near the blade, the cutting angle can be 10 to 20 degrees. However, the blade area with such a sharp cutting angle is easily damaged. In contrast, most domestic companies lack a full understanding of the impact of structural dimensions on the sharpness of knives.

[0006] In summary, it can be seen that there are large gaps in materials, processes, and structures in my country's household knife industry, which directly leads to a disadvantage in the global kitchen knife product market. Therefore, how to seek optimization in materials, processes, and structures to prepare high-performance household knife products that are sharp, durable, antibacterial, and safe is an urgent problem to be solved. Summary of the invention

[0007] In order to solve the deficiencies in the prior art, the present invention provides a household knife and a preparation method thereof, adopts a high entropy alloy doped with Zn and rare earth elements, and utilizes powder rolling and annealing technology to obtain a blade material that has both hardness and toughness and is antibacterial and safe, and combines it with a double trapezoidal knife structure to greatly improve the sharpness and durability of the knife. At the same time, it has the advantages of simple process and suitability for mass production, thereby overcoming the shortcomings of the above-mentioned process.

[0008] In order to achieve the above object, the present invention adopts the following technical solution:

[0009] The present invention provides a household knife, characterized in that it comprises an insulating plastic handle, a blade, a center and a blade, wherein the insulating plastic handle is fixedly connected to the blade, and the blade, the center and the blade are an integrated structure;

[0010] The cross-sectional shape of the blade is a rectangle, the height of the rectangle is 40-50 mm, and the width of the rectangle is 3-6 mm;

[0011] The cross-sectional shape of the knife is an isosceles trapezoid, the height of the knife trapezoid is 10-20 mm, the length of the lower base of the knife trapezoid is the same as the width of the rectangular blade, and the length of the upper base of the knife trapezoid is 60%-70% of the length of the lower base of the knife trapezoid;

[0012] The cross-sectional shape of the blade is an isosceles trapezoid, the height of the blade trapezoid is 5-10 mm, the length of the lower base of the blade trapezoid is the same as the length of the upper base of the blade trapezoid, and the length of the upper base of the blade trapezoid is 10%-20% of the length of the lower base of the blade trapezoid;

[0013] The tool material includes a surface layer material and a core layer material, the surface layer material is arranged on the upper and lower sides of the core layer material respectively, the thickness of the core layer material accounts for 6% to 14% of the total thickness, and is the same as the length of the lower bottom of the blade trapezoid;

[0014] The surface layer material is one of HK30, 316L and 304L doped with C, and the doping amount of C is 0.2~0.5wt.%. The core layer material is AlxCoCrFeNi+yZn+zM, M is one of La and Ce, x is 0.4~0.8, y is 0.2~1wt.%, and z is 0.2~1wt.%.

[0015] The present invention provides a method for preparing a household knife, characterized by comprising the following steps:

[0016] S1: Powder filling: according to the thickness of the surface layer and the core layer, weigh the corresponding weight of each layer of powder, spread it on the bottom of the bag in turn, and vibrate it to make it flat;

[0017] S2: Pre-burning: After the powder is loaded, the package is vacuumed and sealed, and the vacuum degree inside the package is ≤5Pa. The package sample is pre-burned in a vacuum sintering furnace;

[0018] S3: Forming: After pre-sintering, the jacket sample is rolled into shape in multiple passes, with a rolling temperature of 1050~1250℃, a total rolling deformation of 50%~70%, and a single rolling deformation of 10%~20%;

[0019] S4: Annealing: After the hot working is completed, the package and the sample are peeled off and annealing is performed. The annealing process is: from room temperature to 400-600°C at 5-10°C / min, keep the temperature for 1-2h, and cool with the furnace;

[0020] S5: Finishing: After annealing, the tool is finished through finishing.

[0021] As a preferred embodiment, the present invention provides a method for preparing household knives, characterized in that the raw material of the surface layer is a powder prepared by one of gas atomization, water atomization and water-gas combined atomization methods, and the average particle size of the surface layer powder is 5~20um.

[0022] As a preferred embodiment, the present invention provides a method for preparing household knives, characterized in that the raw material of the core layer is prepared by mechanical alloying of elemental metal powder, the purity of the metal element powder is not less than 99.9%, and the average particle size of the metal element powder is 5~20um.

[0023] As a preferred embodiment, the present invention provides a method for preparing household knives, characterized in that the pre-sintering process is: heating from room temperature to 600-800°C at 5-10°C / min, maintaining the temperature for 2-6h, and cooling with the furnace.

[0024] The present invention discloses a household knife and a preparation method thereof, which are characterized in that the hardness is ≥55HRC and the sharpness is ≥100mm.

[0025] Principles and advantages

[0026] In order to improve the problems of complicated heat treatment process and poor toughness of the existing high-carbon and high-chromium stainless steel kitchen knife materials, the present invention adopts a multi-layer material composite form, the non-blade part is stainless steel such as HK30, 316L and 304L, and the blade part adopts a multi-principal high-entropy alloy AlxCoCrFeNi (x is 0.4~0.8). The high-entropy alloy has 5 principal elements, and the atomic fraction of each principal element does not exceed 35%. Under the condition of multiple principal elements, a high entropy effect will be produced, so that the high-entropy alloy has a simple solid solution structure. The high-entropy alloy has excellent comprehensive properties, and its high hardness, high toughness and good wear resistance. By adjusting the Al content, the phase composition of the AlCoCrFeNi high-entropy alloy is controlled to BCC (body-centered cubic) + FCC (face-centered cubic) dual phase, which not only ensures strength but also maintains a certain toughness. Secondly, a trace amount of rare earth elements La or Ce is added to refine the grains. The refinement of the grains can significantly increase the grain boundary density, so that the alloy achieves a very good strengthening effect, and can even improve its plasticity while improving the strength of the alloy. Finally, through annealing treatment at 400~600℃ for 1~2h, a nano-precipitate phase coherent with the matrix is ​​precipitated. This precipitate phase can effectively hinder dislocation movement and thus improve the strength of the alloy. For coherent second phase strengthening, since the precipitate phase is coherent with the matrix and the mismatch is small, this strengthening method can maintain good plasticity while improving the strength of the alloy. Therefore, the new high entropy alloy material and simple annealing process solve the problems of complex heat treatment process and poor toughness of existing high-carbon and high-chromium stainless steel kitchen knife materials, and the hardness is also guaranteed to reach more than 55HRC. In addition to the improvement of strength and toughness, stainless steels such as HK30, 316L and 304L are used in the non-blade part, that is, the non-cutting position to reduce production costs.

[0027] In order to improve the problem of poor interface bonding of composite materials in the existing preparation process and easy detachment of the coating during the use of the kitchen knife, the present invention firstly uses low-temperature pre-sintering to form a certain metallurgical bond between the core layer and the surface layer, and at the same time, by adding an alloy element C with a self-lubricating effect to the surface layer material to adjust its thermal expansion coefficient, it is closer to the core layer high entropy alloy, and the relevant performance of the two is matched, which not only eliminates the obvious interlayer interface of the multilayer structure, but also reduces the thermal stress caused by the different thermal expansion coefficients and improves the bonding strength of the interface. Secondly, the powder rolling technology is adopted to continuously feed the powder blank into the gap between the two rotating rollers, and the pressure of the rollers is rolled into a plate and strip blank with a certain mechanical strength. The powder is continuously bitten into the metallurgical bonding layer by the external friction between the powder and the roller and the friction inside the powder body, which greatly improves the interface bonding strength, so that the core layer can be guaranteed to work long-term as a cutting part, and it is durable.

[0028] The core performance of high-quality cutting tools is sharpness. According to the international standard EN ISO 8442-5 "Test Methods for Cutting Tool Sharpness and Durability", the depth of the cutting tool cutting the standard test piece is used as an indicator to measure the sharpness of the cutting tool. The designated part of the cutting edge of the cutting tool with a length of 40 mm is cut at a uniform speed of 50 mm / s. The total depth of the cutting tool cutting the quartz paper in the first three weeks is defined as the sharpness of the cutting tool. In order to study the influence of structural dimensions on the sharpness of the cutting tool, under the same microstructure, the structural characteristics such as the blade wrap angle (the angle α between the two extension lines along the cutting edge is the blade wrap angle of the cutting tool) and the blade tip thickness (the thickness at the end of the cutting edge) are closely related to the sharpness of the cutting tool. During the technical development process, the inventor tried a single cutting tool structure solution, but no matter how it was optimized, the sharpness of the resulting product was still not ideal. The present invention has determined the double trapezoidal tool structure through a large number of experiments. By designing the middle and blade of two isosceles trapezoidal cross-sections, the middle of the knife with a small blade wrap angle but a large blade tip thickness (equivalent to the upper bottom length of the middle trapezoid of the knife) is firstly adopted, which is located in the middle of the knife. Such a design can avoid the weakening of the edge strength caused by the small blade tip thickness, play a role in strengthening the blade, and prevent the blade from being easily deformed or damaged during use, thereby improving the durability of the blade. Secondly, the blade part with a large blade wrap angle but a small blade tip thickness (equivalent to the upper bottom length of the blade trapezoid) is adopted. By reducing the blade tip thickness, the cutting ability of the tool is improved, and at the same time, the problem of increasing the friction between the tool and the object to be cut and reducing the sharpness of the tool due to the small blade wrap angle is avoided. Under the above-mentioned structural design principle, it is determined that the specific size parameters can obtain a tool with high sharpness and durability, and the sharpness reaches more than 100mm.

[0029] In addition, adding an appropriate amount of Zn element to the high-entropy alloy can adsorb on the surface of fungi, destroy the function of the cell membrane and enter the interior of the cell, causing certain cell components to escape, interfering with the cell metabolism process or the action of various enzymes, causing them to lose their due biological functions, and finally leading to cell death, greatly improving antibacterial safety.

[0030] Compared with the prior art, the present invention provides a household knife and a preparation method thereof, which have the following advantages:

[0031] The process is simple, and the use of new high-entropy alloys and annealing technology improves production efficiency and is easy to achieve mass production;

[0032] High hardness and sharpness. The high-hardness tool material is obtained by refining the grains with rare earth elements and precipitating the coherent second phase. Combined with the double trapezoidal tool structure, a tool with excellent sharpness is obtained.

[0033] It has good antibacterial properties and an appropriate amount of Zn element, which can be adsorbed on the surface of fungi, destroying the function of the cell membrane and entering the interior of the cell, causing certain cell components to escape, interfering with the cell's metabolic process or the action of various enzymes, causing it to lose its proper biological function and ultimately leading to cell death.

[0034] In summary, the present invention provides a household knife and a preparation method thereof, which adopts a high entropy alloy doped with Zn and rare earth elements, and utilizes powder rolling and annealing technology to obtain a blade material that has both hardness and toughness and is antibacterial and safe. Combined with a double trapezoidal knife structure, the sharpness and durability of the knife are greatly improved. At the same time, it has the advantages of simple process and suitability for mass production, and is very suitable for use in household knives. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 This is the microstructure diagram of the high entropy alloy of the present invention, 1-FCC phase, 2-BCC phase.

[0036] Figure 2 This is a transmission electron microscope image of the high entropy alloy of the present invention, 1-coherent second phase.

[0037] Figure 3 It is a side view of the household knife of the present invention, 1-handle, 2-blade, 3-center, 4-blade.

[0038] Figure 4 Based on Figure 3 The cross-sectional structure diagram of the cutting line AA, 1-blade body, 2-blade center, 3-blade edge, a-blade body rectangular width, b-blade center trapezoid lower base length, c-blade edge trapezoid lower base length, d-blade edge trapezoid upper base length, e-blade body rectangular height, f-blade center trapezoid height, g-blade edge trapezoid height.

[0039] Figure 5 Based on Figure 3 Cross-sectional material diagram of the cutting line AA, 1-surface layer, 2-core layer. Implementation

[0040] The method of the present invention is further described below with reference to three examples. Example

[0041] A household knife and a preparation method thereof, wherein the process is as follows:

[0042] S0: Structure & component design: The household knife includes an insulating plastic handle, a blade, a center and a blade. The insulating plastic handle is fixedly connected to the blade, and the blade, the center and the blade are an integrated structure.

[0043] The cross-sectional shape of the blade is a rectangle, the height of the rectangle is 40 mm, and the width of the rectangle is 6 mm;

[0044] The cross-sectional shape of the knife is an isosceles trapezoid, the height of the trapezoid is 10 mm, the length of the lower base of the trapezoid is 6 mm, and the length of the upper base of the trapezoid is 3.6 mm;

[0045] The cross-sectional shape of the blade is an isosceles trapezoid, the height of the blade trapezoid is 5 mm, the length of the lower base of the blade trapezoid is 3.6 mm, and the length of the upper base of the blade trapezoid is 0.4 mm;

[0046] The tool material includes HK30 surface material doped with 0.2wt.%C and Al 0.4 CoCrFeNi+0.5wt.%Zn+0.5wt.%La core layer material, with surface layer materials arranged on the upper and lower sides of the core layer material, and the thickness of the core layer material accounts for 6.7% of the total thickness;

[0047] S1: Powder filling: according to the thickness of the surface layer and the core layer, weigh the corresponding weight of each layer of powder, spread it on the bottom of the bag in turn, and vibrate it to make it flat;

[0048] The raw material of the core layer is prepared by mechanical alloying of single metal powder. The purity of the metal element powder is 99.9%, and the average particle size of the metal element powder is 8um. The raw material of the surface layer is powder prepared by gas atomization method, and the average particle size of the powder is 15um.

[0049] S2: Pre-sintering: After the powder is loaded, the package is vacuumed and sealed. The vacuum degree in the package is ≤5Pa. The package sample is pre-sintered in a vacuum sintering furnace. The temperature is raised from room temperature to 600℃ at 10℃ / min for 4h, and then cooled with the furnace;

[0050] S3: Forming: After pre-burning, the jacket sample is rolled for multiple passes, with a rolling temperature of 1150°C, a total deformation of 60%, and a single deformation of 15%;

[0051] S4: Annealing: After the hot working is completed, the package and the sample are peeled off and annealing treatment is carried out, from room temperature to 500℃ at 5℃ / min for 1h, and then cooled with the furnace;

[0052] S5: Finishing: After annealing, the tool is finished through finishing, with a hardness of 55HRC and a sharpness of 100mm. Example

[0053] A household knife and a preparation method thereof, wherein the process is as follows:

[0054] S0: Structure & component design, the household knife includes an insulating plastic handle, a blade, a center and a blade, the insulating plastic handle is fixedly connected to the blade, and the blade, the center and the blade are an integrated structure;

[0055] The cross-sectional shape of the blade is a rectangle, the height of the rectangle is 50 mm, and the width of the rectangle is 6 mm;

[0056] The cross-sectional shape of the knife is an isosceles trapezoid, the height of the trapezoid is 12 mm, the length of the lower base of the trapezoid is 6 mm, and the length of the upper base of the trapezoid is 3.6 mm;

[0057] The cross-sectional shape of the blade is an isosceles trapezoid, the height of the blade trapezoid is 6 mm, the length of the lower base of the blade trapezoid is 3.6 mm, and the length of the upper base of the blade trapezoid is 0.5 mm;

[0058] The tool material includes 316L surface material doped with 0.3wt.%C and Al 0.5 CoCrFeNi+0.5wt.%Zn+0.5wt.%Ce core layer material, with surface layer materials arranged on the upper and lower sides of the core layer material, and the thickness of the core layer material accounts for 8.3% of the total thickness;

[0059] S1: Powder filling: according to the thickness of the surface layer and the core layer, weigh the corresponding weight of each layer of powder, spread it on the bottom of the bag in turn, and vibrate it to make it flat;

[0060] The raw material of the core layer is prepared by mechanical alloying of single metal powder. The purity of the metal element powder is 99.9%, and the average particle size of the metal element powder is 10um. The raw material of the surface layer is powder prepared by water atomization method, and the average particle size of the powder is 12um.

[0061] S2: Pre-burning: After the powder is loaded, the package is vacuumed and sealed. The vacuum degree in the package is ≤5Pa. The package sample is pre-burned in a vacuum sintering furnace, from room temperature to 650℃ at 10℃ / min for 3h, and then cooled with the furnace;

[0062] S3: Forming: After pre-burning, the jacket sample is rolled for multiple passes, with a rolling temperature of 1150°C, a total deformation of 70%, and a single deformation of 14%;

[0063] S4: Annealing: After the hot working is completed, the package and the sample are peeled off and annealing treatment is carried out, from room temperature to 500℃ at 5℃ / min for 1h, and then cooled with the furnace;

[0064] S5: Finishing: After annealing, the tool is finished through finishing, with a hardness of 56HRC and a sharpness of 110mm. Example

[0065] A household knife and a preparation method thereof, wherein the process is as follows:

[0066] S0: Structure & component design: The household knife includes an insulating plastic handle, a blade, a center and a blade. The insulating plastic handle is fixedly connected to the blade, and the blade, the center and the blade are an integrated structure.

[0067] The cross-sectional shape of the blade is a rectangle, the height of the rectangle is 50 mm, and the width of the rectangle is 5 mm;

[0068] The cross-sectional shape of the knife is an isosceles trapezoid, the height of the trapezoid is 12 mm, the length of the lower base of the trapezoid is 5 mm, and the length of the upper base of the trapezoid is 3.5 mm;

[0069] The cross-sectional shape of the blade is an isosceles trapezoid, the height of the blade trapezoid is 6 mm, the length of the lower base of the blade trapezoid is 3.5 mm, and the length of the upper base of the blade trapezoid is 0.4 mm;

[0070] The tool material includes 304L surface material doped with 0.3wt.%C and Al 0.6 CoCrFeNi+0.4wt.%Zn+0.5wt.%La core layer material, with surface layer materials on the upper and lower sides of the core layer material, and the thickness of the core layer material accounts for 8% of the total thickness;

[0071] S1: Powder filling: according to the thickness of the surface layer and the core layer, weigh the corresponding weight of each layer of powder, spread it on the bottom of the bag in turn, and vibrate it to make it flat;

[0072] The raw material of the core layer is prepared by mechanical alloying of single metal powder. The purity of the metal element powder is 99.9%, and the average particle size of the metal element powder is 12um. The raw material of the surface layer is powder prepared by water-gas combined atomization method, and the average particle size of the powder is 12um.

[0073] S2: Pre-sintering: After the powder is loaded, the package is vacuumed and sealed. The vacuum degree in the package is ≤5Pa. The package sample is pre-sintered in a vacuum sintering furnace. The temperature is raised from room temperature to 600℃ at 10℃ / min for 4h, and then cooled with the furnace;

[0074] S3: Forming: After pre-burning, the jacket sample is rolled for multiple passes, with a rolling temperature of 1200°C, a total deformation of 60%, and a single deformation of 15%;

[0075] S4: Annealing: After the hot working is completed, the package and the sample are peeled off and annealing treatment is carried out, from room temperature to 500℃ at 5℃ / min for 1h, and then cooled with the furnace;

[0076] S5: Finishing: After annealing, the tool is finished through finishing, with a hardness of 58HRC and a sharpness of 120mm.

[0077] The above-described examples are only preferred implementation methods of the present invention, and therefore cannot be used to limit the scope of implementation of the present invention. Other equivalent changes, modifications, substitutions and combinations made in accordance with the principles and contents of the present invention still fall within the protection scope of the present invention.

Claims

1. A household knife, characterized in that: It comprises an insulating plastic handle, a blade body, a knife center and a blade, wherein the insulating plastic handle is fixedly connected to the blade body, and the blade body, the knife center and the blade are an integrated structure; The cross-sectional shape of the blade is a rectangle, the height of the rectangle is 40 to 50 mm, and the width of the rectangle is 3 to 6 mm; The cross-sectional shape of the knife is an isosceles trapezoid, the height of the trapezoid in the knife is 10-20 mm, the length of the lower base of the trapezoid in the knife is the same as the width of the rectangular blade, and the length of the upper base of the trapezoid in the knife is 60%-70% of the length of the lower base of the trapezoid in the knife; The cross-sectional shape of the blade is an isosceles trapezoid, the height of the blade trapezoid is 5 to 10 mm, the length of the lower base of the blade trapezoid is the same as the length of the upper base of the blade trapezoid, and the length of the upper base of the blade trapezoid is 10% to 20% of the length of the lower base of the blade trapezoid; The tool material includes a surface layer material and a core layer material. The surface layer material is disposed on the upper and lower sides of the core layer material. The thickness of the core layer material accounts for 6% to 14% of the total thickness and is the same as the length of the lower bottom of the blade trapezoid. The surface material is one of HK30, 316L and 304L doped with C, the doping amount of C is 0.2-0.5wt.%, and the core material is Al x CoCrFeNi+yZn+zM, M is one of La and Ce, x is 0.4~0.8, y is 0.2~1wt.%, and z is 0.2~1wt.%.

2. A household knife according to claim 1, characterized in that: Hardness ≥55HRC, sharpness ≥100mm.

3. A method for preparing household knives according to claim 1 or 2, characterized in that: The following steps are involved: S1: Powder filling: according to the thickness of the surface layer and the core layer, weigh the corresponding weight of each layer of powder, spread it on the bottom of the package in turn, and vibrate it to make it flat; the raw material of the core layer is prepared by mechanical alloying of single metal powder, the purity of the metal element powder is not less than 99.9%, and the average particle size of the metal element powder is 5-20um; S2: Pre-burning: After the powder is loaded, the package is vacuumed and sealed, and the vacuum degree in the package is ≤5Pa. The package sample is pre-burned in a vacuum sintering furnace; S3: Forming: After pre-sintering, the jacket sample is rolled and formed in multiple passes, the rolling temperature is 1050-1250°C, the total rolling deformation is 50%-70%, and the single rolling deformation is 10%-20%; S4: Annealing: After the hot working is completed, the package and the sample are peeled off and annealing is performed. The annealing process is: from room temperature to 400-600°C at 5-10°C / min, keep the temperature for 1-2h, and cool with the furnace; S5: Finishing: After annealing, the tool is finished through finishing.

4. The method for preparing household knives according to claim 3, characterized in that: The raw material of the surface layer is a powder prepared by one of gas atomization, water atomization and water-gas combined atomization, and the average particle size of the surface layer powder is 5-20 um.

5. The method for preparing household knives according to claim 3, characterized in that: The pre-sintering process is: heating from room temperature to 600-800° C. at 5-10° C. / min, maintaining the temperature for 2-6 hours, and cooling along with the furnace.

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