High performance kitchen knife blade with lamella heterostructure, kitchen knife and method of manufacture

Abstract

The present application relates to the technical fields of kitchen knife manufacturing and metal additive manufacturing, and particularly relates to a high-performance kitchen knife blade with laminar heterogeneous structure, a kitchen knife and a preparation method thereof. The blade is composed of high-carbon martensitic stainless steel layers and strong and tough stainless steel layers which are alternately stacked, adopts a symmetrical sandwich layout, and is provided with strong and tough stainless steel layers on both sides and a high-carbon martensitic stainless steel layer in the middle. The blade is integrally formed by additive manufacturing and is metallurgically combined between layers. After being sharpened, the outer side of the blade edge is exposed to the strong and tough layer, and the core is the hard layer. The present application simultaneously strengthens the functional distribution and integrated heat treatment of outer toughness and inner hardness, and simultaneously considers the high hardness, high wear resistance, anti-chipping, corrosion resistance and other performances of the blade, effectively solves the problem that the hardness and toughness of a single material blade are difficult to be considered, and is suitable for the preparation of various kitchen knives.

Description

Technical Field

[0001] This invention relates to the fields of kitchen knife manufacturing, metal additive manufacturing, and heat treatment strengthening technology, specifically to a high-performance kitchen knife blade with a layered heterostructure, a kitchen knife with a layered heterostructure including the blade, and a method for preparing the kitchen knife blade. Background Technology

[0002] During service, kitchen knife blades must withstand cutting pressure, friction and wear, and lateral impact loads simultaneously. They are also in long-term contact with humid, salty, and organic acid media. Therefore, the materials required to have high hardness (to ensure sharpness and edge retention), good toughness (to resist chipping and breakage), and excellent corrosion resistance.

[0003] Existing single types of steel are insufficient to meet the aforementioned comprehensive requirements. High-carbon martensitic stainless steel has high hardness and good wear resistance, but insufficient toughness, making it prone to chipping or even breakage when chopping hard objects; austenitic or ferritic stainless steel, while possessing excellent plasticity, toughness, and corrosion resistance, has relatively low hardness, poor edge retention, and is prone to dulling and deformation. Optimization through heat treatment alone cannot fundamentally overcome the inverse contradiction between hardness and toughness.

[0004] To address this, the industry has developed multi-material composite cutting tools, such as those made of laminated steel and composite steel, which combine hard steel and tough steel into one piece. However, traditional rolling, forging, or diffusion welding processes have three limitations: First, the control precision of layer thickness and layer sequence is low, making it difficult to achieve precise functional layering in the blade thickness direction; second, the interfaces are mostly mechanical interlocking or diffusion bonding, with limited bonding strength, posing a risk of delamination failure during long-term service; third, the thermal expansion and phase transformation behaviors of different steels vary greatly, and the inadequacy of traditional symmetrical designs leads to stress concentration during heat treatment, easily causing warping or interface cracking.

[0005] Metal additive manufacturing technologies (such as laser melting deposition and laser powder bed melting) offer advantages such as controllable material spatial distribution, interlayer metallurgical bonding, and near-net-shape forming, providing new pathways for the design of heterogeneous structures for knife blades. However, current research has not yet proposed mature symmetrical sandwich structure schemes and corresponding heat treatment regimes for kitchen knife blades, thus failing to fully realize the synergistic performance potential of multi-material composites. Summary of the Invention

[0006] To overcome one of the shortcomings of the existing technology, the present invention provides a high-performance kitchen knife blade with a layered heterogeneous structure and its preparation method, aiming to solve the problems of difficulty in achieving both high hardness and high toughness in existing kitchen knife blades, and easy wear or breakage of the blade edge.

[0007] A further objective of this invention is to: utilize additive manufacturing to achieve precise multi-material layering in the blade region; significantly improve the blade's hardness and wear resistance through a heat treatment process dominated by high-carbon martensitic stainless steel; utilize heterogeneous interfaces and tough layers to inhibit crack propagation and improve the blade's anti-chipping performance; and achieve the functional allocation of a kitchen knife with "high hardness and wear resistance in the blade core and relatively high toughness and corrosion resistance in the surface layer."

[0008] To achieve the above objectives, the present invention adopts the following technical solution: A high-performance kitchen knife blade with a layered heterogeneous structure, wherein the blade has a layered heterogeneous structure composed of alternating layers of high-carbon martensitic stainless steel and tough stainless steel; the layers of the layered heterogeneous structure extend parallel to the length direction of the blade and are stacked along the thickness direction of the blade. The blade adopts a symmetrical sandwich layout, with both sides of the blade thickness direction being high-strength stainless steel layers, and at least one high-carbon martensitic stainless steel layer in the middle; the high-strength stainless steel layer is an austenitic stainless steel layer and / or a ferritic stainless steel layer. The blade is integrally formed using an additive manufacturing process, with metallurgical bonding between the layers.

[0009] In some feasible embodiments, the lamellar heterostructure comprises at least three composite layers, and the number of tough stainless steel layers is one more than the number of high-carbon martensitic stainless steel layers.

[0010] In some feasible embodiments, the high-carbon martensitic stainless steel is selected from one or more of 440A, 440B, 440C, 9Cr18, 9Cr18Mo, 95Cr18, and 10Cr15CoMoV.

[0011] In some feasible embodiments, the austenitic stainless steel is selected from one or more of 301, 304, 304L, 316, and 316L; and the ferritic stainless steel is selected from one or more of 409, 410L, 430, 439, and 444.

[0012] In some feasible embodiments, the cross-section of the blade after sharpening has a structure in which an outer tough stainless steel layer is covered and a core high-carbon martensitic stainless steel layer is supported; the high-carbon martensitic stainless steel layer has a martensitic strengthening structure and / or a dispersed carbide strengthening structure after heat treatment.

[0013] In some feasible embodiments, after heat treatment, a microstructure transition zone is formed at the interface between the high-carbon martensitic stainless steel layer and the tough stainless steel layer, and the microstructure transition zone is a recrystallized equiaxed crystal structure.

[0014] In some feasible embodiments, the thickness of a single layer of the lamellar heterostructure is 20 μm to 1.5 mm.

[0015] In some feasible embodiments, the thickness of a single layer of the lamellar heterostructure is 30 μm to 500 μm.

[0016] In some feasible embodiments, the cutting edge angle after sharpening is 10° to 40°.

[0017] In some feasible embodiments, a compositionally gradient transition layer is provided between the high-carbon martensitic stainless steel layer and the tough stainless steel layer, the transition layer being used to reduce interlayer stress concentration.

[0018] The present invention also provides a kitchen knife with a layered heterogeneous structure, including a blade, a handle, and the above-mentioned high-performance kitchen knife blade with a layered heterogeneous structure; the blade is fixed to the cutting edge region of the blade by welding or mechanical fitting, or the blade is formed in situ in the cutting edge region of the blade by additive manufacturing and forms an integral structure with the blade.

[0019] In some feasible embodiments, the blade is made of one or more of austenitic stainless steel, ferritic stainless steel, martensitic stainless steel, low alloy steel, and composite steel.

[0020] This invention also provides a method for preparing the above-mentioned high-performance kitchen knife blade with a layered heterostructure, comprising the following steps: Step 1. Design a layered heterogeneous structure for the blade area. The layered heterogeneous structure is composed of alternating layers of high-carbon martensitic stainless steel and high-toughness stainless steel. The layers of the layered heterogeneous structure extend parallel to the length of the blade and are stacked along the thickness of the blade. Step 2. Prepare the blade blank using additive manufacturing technology. Use a symmetrical sandwich layout for layer-by-layer deposition so that the two sides of the blade blank in the thickness direction are strong and tough stainless steel layers, and at least one layer of high carbon martensitic stainless steel is set in the middle to obtain a layered composite blade blank with alternating "hard-tough" properties. Step 3. Integrated heat treatment strengthening: The layered composite blade blank is subjected to an integrated heat treatment, which includes at least austenitization, quenching and tempering. The heat treatment is carried out in accordance with the strengthening regime of high carbon martensitic stainless steel, so as to promote the full martensitic transformation of the high carbon martensitic stainless steel layer and obtain a dispersed carbide strengthening structure. At the same time, the tough stainless steel layer is recrystallized and the structure is homogenized, resulting in a heterogeneous blade with gradient properties. Step 4. Connect the heat-treated blade blank to the blade body to obtain a combined tool blank; or, directly prepare the blade blank in situ by additive manufacturing in a predetermined cutting area of ​​the blade body, so that the blade blank and the blade body form an integral tool blank. Step 5. Grind, finish and sharpen the knife blank obtained in Step 4 to obtain a layered heterogeneous kitchen knife. After sharpening, the outermost exposed layer of the blade is a tough stainless steel layer, and the core of the blade is a high-carbon martensitic stainless steel layer.

[0021] In some feasible embodiments, the additive manufacturing technology is laser melting deposition, laser powder bed melting, or a combination of both.

[0022] In some feasible embodiments, in step 2, the number of tough stainless steel layers is one more than the number of high-carbon martensitic stainless steel layers.

[0023] In some feasible embodiments, in step 3, the austenitizing treatment temperature is 960℃~1100℃, and after holding at this temperature, oil quenching, gas quenching, vacuum quenching, or salt bath quenching are performed; the tempering treatment temperature is 150℃~300℃, and the tempering time is 1h~4h.

[0024] In some feasible embodiments, step 3. further includes cryogenic treatment after quenching; the temperature of the cryogenic treatment is -80℃ to -196℃, and the treatment time is 0.5h to 24h.

[0025] In some feasible embodiments, in step 2, a compositionally graded transition layer is deposited between the high-carbon martensitic stainless steel layer and the tough stainless steel layer to reduce interlayer stress concentration.

[0026] Compared to existing technologies, the advantages of this invention are as follows: The high-performance kitchen knife blade with a layered heterogeneous structure provided by this invention forms a functional gradient structure in the blade thickness direction through a symmetrical sandwich layout of alternating high-carbon martensitic stainless steel layers and tough stainless steel layers, characterized by "high toughness and corrosion resistance on the outer side and high hardness and wear resistance in the core." The outer tough stainless steel layer can buffer impact loads, inhibit the initiation of microcracks, and resist the humid and salty environment of the kitchen; the core high-carbon martensitic stainless steel layer, after heat treatment, obtains a martensitic strengthened structure and dispersed carbides, providing high hardness support and excellent wear resistance for the blade edge, ensuring sharpness retention. The blade is integrally formed by additive manufacturing, with metallurgical bonding between the layers, resulting in high bonding strength and eliminating the delamination risks of traditional composite knives; after heat treatment, a transition zone is formed at the interface, with a continuous gradient change in hardness, and no mechanically weak areas. The symmetrical sandwich structure can balance the thermal stress and phase transformation stress caused by the differences in the thermophysical properties of different materials, reducing the risk of warping deformation and interface instability. The multi-layered heterogeneous interface deflects, branches, and blunts cracks, effectively preventing crack propagation and improving chipping resistance. After sharpening, the outer layer of tough stainless steel covers the cutting edge, and the core hard layer is adjacent to the tip, achieving a synergistic improvement in sharpness and impact resistance. This effectively solves the technical challenge of achieving both hardness and toughness in blades made of a single material. Attached Figure Description

[0027] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0028] Figure 1 This is a schematic diagram of the overall structure of the layered heterogeneous kitchen knife of the present invention; Figure 2 This is a schematic diagram of the overall structure of the blade of the kitchen knife with the layered heterogeneous structure of the present invention; Figure 3 This is a schematic cross-sectional view of the layered heterogeneous structure in the blade region of the present invention; Figure 4 This is a schematic diagram of the metallographic structure of the heterogeneous interface in an embodiment of the present invention; Figure 5 This is a hardness gradient distribution diagram of the blade of a kitchen knife with a layered heterogeneous structure in an embodiment of the present invention; Figure 6 The image shows the XRD pattern of the blade of a kitchen knife with a layered heterostructure in an embodiment of the present invention. Figure 7 This is a flowchart of the preparation method of the present invention.

[0029] Explanation of reference numerals in the attached diagram: 1-blade; 2-handle; 3-blade edge; 31-upper tough stainless steel layer; 32-lower tough stainless steel layer; 33-high carbon martensitic stainless steel layer; 34-edge; 35-core of the blade. Detailed Implementation

[0030] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0031] Reference Figures 1 to 7As shown, this embodiment provides a high-performance kitchen knife blade with a layered heterogeneous structure. The blade 3 has a layered heterogeneous structure composed of alternating layers of high-carbon martensitic stainless steel 33 and tough stainless steel. The layers of the layered heterogeneous structure extend parallel to the length direction of the blade body 1 and are stacked along the thickness direction of the blade 3. The extension direction of each layer matches the main force direction during cutting, which can ensure the mechanical stability of the interlayer bonding and avoid delamination failure caused by the cutting load acting directly on the interface. The blade 3 adopts a symmetrical sandwich layout, with tough stainless steel layers on both sides of the blade 3 in the thickness direction, namely an upper tough stainless steel layer 31 on the upper side of the blade and a lower tough stainless steel layer 32 on the lower side of the blade. At least one layer of high-carbon martensitic stainless steel 33 is provided in the middle area, forming a structure with two sides covering and a rigid support in the middle. After sharpening, the outermost exposed layer of the cutting edge 34 is a tough stainless steel layer, while the core of the blade 35 is a high-carbon martensitic stainless steel layer 33, thus forming a functional zone of "tough outer layer and hard inner layer". The tough stainless steel layer is an austenitic stainless steel layer and / or a ferritic stainless steel layer, which has the performance characteristics of high toughness, good plasticity and excellent corrosion resistance, and can undertake the functions of impact resistance, chipping prevention and corrosion resistance; the high-carbon martensitic stainless steel layer 33 can obtain high hardness and high wear resistance after heat treatment, providing rigid support and wear resistance for the cutting edge. The blade 3 is integrally formed by additive manufacturing process, and the adjacent different material layers are metallurgically bonded by molten pool, with high interface bonding strength and no mechanical bonding interface and delamination risks common in traditional composite processes.

[0032] In some feasible embodiments, the layered heterostructure comprises at least three composite layers, with the number of tough stainless steel layers being one more than the number of high-carbon martensitic stainless steel layers. In practical applications, the most basic configuration is a three-layer symmetrical sandwich structure of "tough stainless steel layer / high-carbon martensitic stainless steel layer / tough stainless steel layer." This structure is simple, has a short manufacturing process, and can meet the performance requirements of most basic kitchen knives. Based on this, the number of intermediate high-carbon martensitic stainless steel layers can be increased according to performance requirements, and the number of symmetrically distributed tough stainless steel layers can be increased accordingly, for example, a seven-layer structure or even a more complex structure. By maintaining that the number of tough stainless steel layers is one more than the number of high-carbon martensitic stainless steel layers, the symmetrical layout in the blade thickness direction can be maintained at all times, ensuring that the tough stainless steel layers on both sides can completely cover the internal hard layer, while balancing the stress problems caused by the differences in the thermophysical properties of different materials, and avoiding warping, deformation, or interface cracking during heat treatment.

[0033] In some feasible embodiments, the high-carbon martensitic stainless steel is selected from one or more of 440A, 440B, 440C, 9Cr18, 9Cr18Mo, 95Cr18, and 10Cr15CoMoV. These steels all belong to the high-carbon martensitic stainless steel category, and their carbon content and alloy element content are suitable for heat treatment strengthening requirements. After austenitization, quenching, and tempering, a martensitic matrix and dispersed carbide structure can be formed, resulting in high hardness and excellent wear resistance, making them ideal materials for the core support layer of kitchen knife blades.

[0034] In some feasible embodiments, austenitic stainless steel is selected from one or more of 301, 304, 304L, 316, and 316L; ferritic stainless steel is selected from one or more of 409, 410L, 430, 439, and 444. Austenitic stainless steel possesses excellent plasticity, toughness, and corrosion resistance, is non-magnetic, and can absorb energy through plastic deformation under cutting impact loads, effectively buffering stress concentration. It also resists the corrosion of moisture, salt, and organic acids in the kitchen environment, making it the mainstream choice for the outer toughening layer. Ferritic stainless steel also possesses good corrosion resistance and thermal conductivity, with a low coefficient of thermal expansion, resulting in better thermal matching with high-carbon martensitic stainless steel, further reducing interlayer thermal stress and minimizing the risk of heat treatment deformation.

[0035] In some feasible embodiments, the cross-section of the sharpened blade has a structure consisting of an outer layer of tough stainless steel and a core layer of high-carbon martensitic stainless steel. The high-carbon martensitic stainless steel layer, after heat treatment, possesses a martensitic strengthening structure and / or a dispersed carbide strengthening structure. After sharpening, the tip region of the blade is formed by the tough stainless steel layers on both sides, with the high-carbon martensitic stainless steel core adjacent to the tip, providing rigid support for the cutting edge. This avoids the problem of high-hardness material being easily chipped due to impact when directly exposed to the cutting edge surface, while also ensuring the cutting rigidity and wear resistance of the cutting edge, achieving a balance between sharpness and chip resistance. After integrated heat treatment, a full martensitic phase transformation occurs within the high-carbon martensitic stainless steel layer, simultaneously precipitating dispersed alloy carbides. Through phase transformation strengthening and second-phase strengthening, the hardness and wear resistance of the material are jointly improved, providing a solid microstructure foundation for the long-term sharpness retention of the cutting edge.

[0036] In some feasible embodiments, after heat treatment, a microstructure transition zone is formed at the interface between the high-carbon martensitic stainless steel layer and the tough stainless steel layer. This transition zone exhibits a recrystallized equiaxed crystal structure, with no obvious hardness troughs, microcracks, or porosity at the interface. Based on the molten pool metallurgical bonding of additive manufacturing, the subsequent heat treatment process promotes elemental diffusion and microstructure recrystallization in the interface region, forming a transition zone with a gentle transition in composition and microstructure, rather than a steep, direct bonding interface. The microstructure of this transition zone is recrystallized equiaxed crystals with uniform and fine grains, effectively mitigating abrupt property changes between the two materials and reducing the risk of stress concentration at the interface. From a mechanical perspective, the hardness of the interface transition zone is between that of the high-carbon martensitic stainless steel layer and the tough stainless steel layer, exhibiting a continuous gradient change without obvious hardness troughs or mechanically weak areas. Simultaneously, the interface region is free of metallurgical defects, including microcracks, porosity, and inclusions, ensuring the mechanical strength and structural stability of the interlayer bond and preventing interface delamination failure during long-term tool use.

[0037] In some feasible embodiments, the thickness of a single layer in the lamellar heterostructure ranges from 20 μm to 1.5 mm. Single-layer thickness is a key parameter affecting the performance of the heterostructure. Within this range, the single-layer thickness can be adjusted to suit different additive manufacturing processes and performance requirements. Thinner single-layer thicknesses result in a greater number of heterostructure interfaces, enhancing interfacial crack resistance, smoothing performance gradients, and improving overall cutting edge toughness; however, this increases the number of fabrication layers and production cycle. Thicker single-layer thicknesses improve fabrication efficiency and highlight the performance characteristics of each layer, making the supporting role of the core hard layer and the buffering role of the outer tough layer more significant, suitable for high-load cutting scenarios.

[0038] In some feasible embodiments, the thickness of a single layer in the layered heterostructure ranges from 30 μm to 500 μm. This range is a preferred single-layer thickness range, ensuring a sufficient number of heterostructure interfaces to fully exert the crack-resistant and toughening effect while maintaining the fabrication efficiency of additive manufacturing and avoiding excessively long production cycles and increased costs due to too many layers. Simultaneously, this thickness range matches the forming capabilities of mainstream laser melting deposition and laser powder bed melting processes, enabling stable molten pool metallurgical bonding and uniform layer thickness control, ensuring forming quality and batch consistency. For most household kitchen knives and professional chef's knives, layered structures within this thickness range achieve a good balance between hardness, toughness, and manufacturing cost, possessing high engineering application value and industrialization potential.

[0039] In some feasible embodiments, the cutting angle of the blade after sharpening is 10° to 40°. The size of the cutting angle directly determines the cutting sharpness and edge strength of the knife. A smaller cutting angle provides a sharper cutting feel and less cutting resistance, but the edge strength is relatively lower, making it prone to chipping under lateral forces or impacts. A larger cutting angle provides higher edge strength, stronger resistance to chipping, and can withstand greater impact loads, but the cutting resistance is greater, and the sharpness is somewhat reduced. By adjusting the cutting angle parameters within the range of 10° to 40°, the needs of kitchen knives for different purposes can be adapted: for example, fruit knives, chef's knives, and Japanese cooking knives used for precision cutting can use a smaller cutting angle to ensure cutting sharpness and a good cutting feel; chopping knives and cleavers used for chopping can use a larger cutting angle to improve the edge's impact resistance and chipping resistance, synergizing with the performance characteristics of the layered heterogeneous structure to maximize the structural advantages.

[0040] In some feasible embodiments, a transition layer is provided between the high-carbon martensitic stainless steel layer and the tough stainless steel layer to reduce interlayer stress concentration. When the two materials have significant differences in their coefficients of thermal expansion, elastic modulus, and phase transformation behavior, a transition layer with a gradual change in composition can be added between the high-carbon martensitic stainless steel layer and the tough stainless steel layer. By gradually adjusting the composition and properties of the materials, the abrupt change in properties between the two materials can be mitigated, further reducing interlayer stress concentration during heat treatment and use, and improving the stability of the interface bonding. The transition layer can be prepared in situ by gradually adjusting the powder feeding ratio during additive manufacturing, achieving a continuous transition of composition, avoiding the emergence of new weak interfacial areas, and further improving the overall mechanical properties and service reliability of the layered heterostructure. This is particularly suitable for heterostructure designs with a large number of layers and significant performance differences.

[0041] This invention also provides a layered heterogeneous structure kitchen knife, including a blade 1, a handle 2, and the aforementioned high-performance kitchen knife blade 3 with a layered heterogeneous structure. The blade 3 is fixed to the cutting edge region of the blade 1 by welding or mechanical fitting, or the blade 3 is formed in situ in the cutting edge region of the blade 1 by additive manufacturing and forms an integral structure with the blade 1. The handle 2 is used for user gripping and operation, and is typically designed with anti-slip and ergonomic features to improve grip comfort and operational stability. The blade 1, as the main structure of the knife, bears the functions of load transfer and structural support, while the blade 3 is located in the front cutting edge region of the blade and undertakes the core cutting function. The connection method between the blade and the blade body can be flexibly selected according to the production process and product positioning: When adopting a split design, the pre-made heterogeneous blade structure can be welded to the cutting edge of the blade body through laser welding or other methods, or fixed through mechanical fitting, riveting or other methods. This process is highly flexible and facilitates modular production and component replacement. When adopting an integrated design, the layered heterogeneous blade structure can be directly deposited in situ in the cutting edge area of ​​the blade body blank through additive manufacturing. A metallurgical bond is formed between the blade body and the blade, resulting in higher overall structural strength and no weak connection links. This is suitable for knife products used in high-load and high-intensity scenarios.

[0042] In some feasible embodiments, the blade is made of one or more of austenitic stainless steel, ferritic stainless steel, martensitic stainless steel, low-alloy steel, and composite steel. The choice of blade material can be determined based on the overall positioning of the tool, cost control, and performance requirements. Good metallurgical compatibility between the blade material and the cutting edge material ensures the bonding quality during welding or in-situ additive manufacturing, avoids connection defects and stress concentration, and ensures the overall structural reliability of the tool.

[0043] This invention also provides a method for preparing a high-performance kitchen knife blade with a layered heterostructure, comprising the following steps: Step 1. Design the layered heterogeneous structure of the cutting edge region. The layered heterogeneous structure consists of alternating layers of high-carbon martensitic stainless steel and high-toughness stainless steel. The layers of the layered heterogeneous structure extend parallel to the length of the blade and are stacked along the thickness direction of the cutting edge. During the design phase, based on the purpose, performance requirements, and size specifications of the target tool, determine the total number of layers, the material selection for each layer, the thickness of each layer, and the overall layout. Strictly adhere to the design principle of symmetrical sandwich layers, and clarify the deposition sequence and thickness parameters of each layer to provide clear process basis and quality judgment standards for subsequent fabrication.

[0044] Step 2. An additive manufacturing process is used to prepare the blade blank. A symmetrical sandwich structure is employed for layer-by-layer deposition, resulting in a blade blank with strong, tough stainless steel layers on both sides along its thickness direction and at least one layer of high-carbon martensitic stainless steel in the middle, creating a layered composite blade blank with alternating "hard-tough" properties. During deposition, different metal powders are melted sequentially according to a pre-defined layer sequence. Metallurgical bonding between layers is achieved through solidification in the molten pool, and the layers are stacked one by one to form a complete blade blank. Strict control of additive manufacturing process parameters is maintained throughout the process to ensure forming quality, layer thickness accuracy, and interface bonding, avoiding metallurgical defects such as porosity, cracks, and lack of fusion.

[0045] Step 3. Integrated Heat Treatment Strengthening: The layered composite blade blank undergoes an integrated heat treatment, including at least austenitization, quenching, and tempering. The heat treatment follows the strengthening regime for high-carbon martensitic stainless steel, promoting full martensitic transformation of the high-carbon martensitic stainless steel layer and achieving a dispersed carbide-reinforced microstructure. Simultaneously, it causes recrystallization and microstructure homogenization of the tough stainless steel layer, resulting in a heterogeneous blade with gradient properties. This integrated heat treatment simultaneously controls the microstructure of both materials, achieving hardening and strengthening of the hard layer while optimizing the microstructure of the tough layer. It also promotes interfacial element diffusion and transition zone formation, improving interfacial bonding performance, thus achieving overall performance control in a single heat treatment.

[0046] Step 4. Join the heat-treated blade blank to the blade body to obtain a combined tool blank. Alternatively, directly prepare the blade blank in situ using additive manufacturing in a predetermined cutting area of ​​the blade body, forming an integral structure between the blade blank and the blade body. Select either a separate joining or in-situ forming process route based on the product plan to achieve a reliable connection between the blade and the blade body, resulting in a complete tool blank. The joining process requires control of process parameters to avoid negatively impacting the microstructure and performance of the blade.

[0047] Step 5. Grinding, finishing, and sharpening the knife blank obtained in Step 4 to obtain a layered heterogeneous structure kitchen knife. After sharpening, the outermost exposed layer of the blade edge is a strong and tough stainless steel layer, and the core of the blade is set with a high-carbon martensitic stainless steel layer. Grinding is used to correct dimensional deviations caused by additive manufacturing and heat treatment, improving surface quality and dimensional accuracy. Then, sharpening is used to form the final blade shape. At the same time, the sharpening depth and grinding amount are precisely controlled to ensure that the surface of the blade edge retains a continuous strong and tough stainless steel layer, and the high-carbon martensitic stainless steel core layer near the blade tip provides rigid support, realizing the preset functional zoning structure.

[0048] In some feasible embodiments, additive manufacturing technologies include laser melting deposition, laser powder bed melting, or a combination of both. Laser melting deposition offers high forming efficiency and flexible powder feeding methods, making it suitable for preparing large-sized, thick blade blanks. It also allows for flexible adjustment of powder composition to create in-situ transition layers with gradual compositional changes. Laser powder bed melting offers high forming precision and low surface roughness, making it suitable for preparing thin-layered, multi-layered, fine heterogeneous structures. It enables thinner single-layer thicknesses and more uniform layer thickness control, providing greater freedom in structural design.

[0049] In some feasible embodiments, in step 2, the number of tough stainless steel layers is one more than the number of high-carbon martensitic stainless steel layers. During the deposition process, the tough stainless steel layer is used as both the starting and ending layer, with high-carbon martensitic stainless steel layers and tough stainless steel layers deposited alternately in between. This ensures that in the final layered structure, the tough stainless steel layer always outnumbers the high-carbon martensitic stainless steel layer, maintaining a symmetrical layout in the thickness direction. This deposition strategy ensures that both the upper and lower surfaces of the blade blank are covered with tough stainless steel layers, which is beneficial for forming an outer covering functional structure after subsequent sharpening, and also helps to balance stress during heat treatment, reducing the risk of deformation and cracking, and ensuring product yield and batch stability.

[0050] In some feasible embodiments, in step 3, the austenitizing temperature is 960℃~1100℃, followed by oil quenching, gas quenching, vacuum quenching, or salt bath quenching; the tempering temperature is 150℃~300℃, and the tempering time is 1h~4h. The austenitizing temperature setting must ensure that the carbides in the high-carbon martensitic stainless steel are fully dissolved to obtain a uniform supersaturated austenitic structure, providing a microstructure basis for subsequent martensitic phase transformation, while avoiding excessively high temperatures that could lead to coarse grains and decreased toughness. The quenching process can be flexibly selected according to material characteristics, workpiece size, and production conditions. Rapid cooling promotes the transformation of austenite to martensite, achieving a hardening effect. Tempering is used to eliminate residual quenching stress and adjust the balance between toughness and hardness. By controlling the tempering temperature and time, different hardness levels of blade structure can be obtained to suit different application requirements. Within this process parameter range, the high-carbon martensitic stainless steel layer can obtain sufficient strengthening effect while avoiding performance degradation and microstructural abnormalities in the strong and tough stainless steel layer.

[0051] In some feasible embodiments, step 3 includes cryogenic treatment after quenching; the cryogenic treatment temperature is -80℃ to -196℃, and the treatment time is 0.5h to 24h. Cryogenic treatment can further reduce the residual austenite content in the high-carbon martensitic stainless steel layer, promote the transformation of more metastable austenite into martensite, and promote the precipitation of fine dispersed carbides, further improving the hardness and wear resistance of the blade edge, and improving the dimensional stability and long-term accuracy retention of the cutting edge. For high-end kitchen knife blades with high hardness requirements, a cryogenic treatment process can be added after quenching, followed by tempering, to obtain a better strengthening effect. The temperature and time of cryogenic treatment can be adjusted within the above range according to the material type and performance objectives to ensure the strengthening effect while avoiding excessive embrittlement of the material.

[0052] In some feasible embodiments, in step 2, a transition layer is deposited between the high-carbon martensitic stainless steel layer and the tough stainless steel layer to reduce interlayer stress concentration. When it is necessary to prepare a heterogeneous structure with a transition layer, the powder feeding ratio of the two powders can be gradually adjusted during the deposition of the two materials to prepare a transition layer with continuously changing composition in situ, achieving a smooth transition between the two materials. This process can complete the preparation of the transition layer without adding extra steps. The transition layer and the substrate layers on both sides are metallurgically bonded with no obvious interface, which can effectively alleviate the abrupt changes in composition and properties between layers, reduce thermal stress and phase transformation stress concentration, further improve the interfacial bonding strength and the fatigue resistance of the structure, and extend the service life of the tool.

[0053] To more clearly demonstrate the implementation process and technical effects of the present invention, the following detailed description is provided in conjunction with three specific preparation examples.

[0054] Example 1 This embodiment uses laser melting deposition (LMD) technology to prepare a kitchen knife blade with a three-layer symmetrical sandwich structure. The complete implementation process is as follows: 1. Raw material preparation Gas-atomized 304 austenitic stainless steel powder was selected as the raw material for the strong and tough stainless steel layer, and gas-atomized 440C high-carbon martensitic stainless steel powder was selected as the raw material for the high-carbon martensitic stainless steel layer. The particle size of both powders was screened to be 45-150μm. Before use, the powders were placed in a vacuum drying oven to dry them, removing the moisture adsorbed by the powders and ensuring smooth powder feeding and stable molten pool formation.

[0055] 2. Structural Design The blade design features a three-layer symmetrical sandwich structure consisting of "304 stainless steel / 440C stainless steel / 304 stainless steel". Each layer extends along the length of the blade, forming a three-layer stack along the thickness of the blade. The top and bottom two layers are made of 304 stainless steel, which forms a strong and tough outer layer, while the middle layer is made of 440C stainless steel, which forms a hard core. The overall sandwich layout is completely symmetrical, with each layer designed to be 1mm thick, resulting in a total blade blank thickness of 3mm.

[0056] 3. Laser melting deposition forming A coaxial powder-feed laser melting deposition system was used, with 304 stainless steel plate as the prefabricated substrate. Layer-by-layer deposition was performed under an argon protective atmosphere, with the argon flow rate set to 15 L / min. The oxygen content was controlled to be below 100 ppm throughout the process to avoid high-temperature oxidation of the molten pool. The scanning path was arranged along the length of the cutter body, and the scanning overlap rate was controlled to 40% to ensure the fusion quality within and between layers.

[0057] For different materials, corresponding process parameters were matched: when depositing a 440C high-carbon martensitic stainless steel layer, the laser power was set to 1400W, the scanning speed to 8mm / s, and the powder feed rate to 0.8rpm; when depositing a 304 austenitic stainless steel layer, the laser power was set to 1000W, the scanning speed to 8mm / s, and the powder feed rate to 0.8rpm. The layers were deposited sequentially in the order of "304 layer - 440C layer - 304 layer," resulting in a layered composite blade blank.

[0058] 4. Integrated heat treatment strengthening The formed blade blank is separated from the substrate by wire cutting. After cleaning the surface attachments, it is placed in a heat treatment furnace for overall heat treatment. The heat treatment regime is based on the strengthening specifications of 440C stainless steel: first, it is heated to 1000℃ at a heating rate of 5℃ / min for austenitization treatment. After holding at this temperature until the microstructure is fully transformed, it is taken out of the furnace and oil quenched. After quenching and cooling to room temperature, it is tempered at a tempering temperature of 180℃. After holding at this temperature for 2 hours, it is air-cooled. A total of 2 tempering processes are performed.

[0059] After heat treatment, the microstructure and properties were tested: the core 440C layer underwent a complete martensitic transformation and precipitated dispersed alloy carbides, achieving a microhardness of 656.8 HV, exhibiting excellent wear resistance; the outer 304 austenitic stainless steel layer maintained the austenitic matrix structure, with a hardness of 225 HV, still possessing excellent plasticity and toughness; a uniformly wide microstructure transition zone was formed at the interface between 304 and 440C, containing recrystallized equiaxed crystals with a hardness of approximately 435 HV, showing a continuous gradient transition without abrupt hardness changes or mechanically weak areas. Scanning electron microscopy revealed no metallurgical defects such as microcracks, porosity, or lack of fusion in the interface area, indicating good interlayer metallurgical bonding.

[0060] 5. Blade assembly and sharpening finishing The heat-treated heterogeneous blade is butt-welded to the 304 stainless steel blade body using laser welding. After welding, stress relief treatment is performed to eliminate residual welding stress. The entire knife is then subjected to surface grinding and contour finishing to correct dimensional deviations caused by heat treatment and welding, improving surface finish. Finally, the blade is sharpened by controlling the grinding wheel feed and sharpening depth to ensure a continuous 304 stainless steel layer on both sides of the blade, with the 440C core layer forming a rigid support adjacent to the blade tip, ultimately resulting in a layered, heterogeneous kitchen knife.

[0061] The kitchen knife blade prepared in this embodiment has a corrosion-resistant and chip-resistant outer layer and a high-hardness and wear-resistant core. It has a sharp cutting feel and excellent edge retention. Its impact resistance is better than that of single-material knives of the same hardness. It is especially suitable for kitchen knife products such as chef's knives and slicing knives that focus on fine cutting.

[0062] Example 2 This embodiment uses laser powder bed melting (LPBF) technology to prepare multilayered, alternating symmetrical sandwich cutting edges. The complete implementation process is as follows: 1. Raw material preparation Gas-atomized 430 ferritic stainless steel powder was selected as the raw material for the strong and tough stainless steel layer, and gas-atomized 440C high-carbon martensitic stainless steel powder was selected as the raw material for the high-carbon martensitic stainless steel layer. The particle size of both powders was screened to be 15-53 μm, which meets the powder spreading requirements of the laser powder bed melting process. The powders were vacuum dried before use to avoid agglomeration that would affect the uniformity of powder spreading.

[0063] 2. Structural Design The design incorporates a multi-layered, alternating symmetrical sandwich structure, with layers stacked alternately in units of "430 layers / 440C layers." The first and last layers are both 430 ferritic stainless steel layers, totaling 59 layers. These include 30 layers of high-strength stainless steel and 29 layers of high-carbon martensitic stainless steel. The number of high-strength layers is one more than the number of hard layers, maintaining a symmetrical layout along the thickness direction. The thickness of a single powder layer is designed to be 50μm, resulting in a total blade blank thickness of approximately 3mm after forming.

[0064] 3. Laser powder bed melting A laser powder bed melting system is used, with a stainless steel substrate as the forming base. Layer-by-layer powder spreading and selective laser melting are performed under an argon protective atmosphere. The powder spreading device uniformly spreads powder layer by layer, while the laser beam selectively scans and melts the powder according to the slice outline, stacking the layers one by one. The scanning overlap rate is controlled at 60% to ensure dense fusion within the layers.

[0065] For different materials, corresponding process parameters were matched: when scanning the 440C high-carbon martensitic stainless steel layer, the laser power was set to 350W and the scanning speed was set to 1000mm / s; when scanning the 430 ferritic stainless steel layer, the corresponding process window was matched to ensure a stable molten pool, dense formation, and no obvious spheroidization or warping defects. All 59 layers were deposited according to the preset alternating layer sequence to obtain a multi-layered heterogeneous blade blank.

[0066] 4. Integrated heat treatment strengthening The formed blank is separated from the substrate and first undergoes low-temperature stress-relieving annealing to eliminate residual thermal stress accumulated during additive manufacturing. Then, it undergoes overall strengthening heat treatment: first, it is heated to 980℃ for austenitization treatment, and after sufficient holding, it is quenched with high-pressure argon gas. After quenching, it is transferred to a cryogenic equipment for cryogenic treatment at a temperature of -196℃ for 8 hours to further transform residual austenite and refine the microstructure. After cryogenic treatment, it is taken out and tempered at a temperature of 200℃, and then air-cooled after holding. A total of 3 tempering processes are performed.

[0067] After this process, the core 440C layer acquires a high-hardness martensitic structure and dispersed carbides, resulting in outstanding wear resistance. The outer 430 ferritic stainless steel maintains excellent corrosion resistance and toughness, with a better match between its coefficient of thermal expansion and 440C, and lower interlayer stress levels. The multi-layered, alternating heterogeneous interfaces form a multi-level crack-resistant structure. During crack propagation, multiple interface crossings are required, significantly extending the propagation path and substantially increasing fracture energy. This results in a marked improvement in the cutting edge's resistance to chipping and fracture. The symmetrical layered layout effectively balances phase transformation stress and thermal stress during heat treatment, minimizing billet warping and maintaining good dimensional accuracy.

[0068] 5. Blade assembly and sharpening finishing The heat-treated multi-layered heterogeneous blade is connected to the 2Cr13 stainless steel blade body via laser welding, followed by grinding and sharpening. During the sharpening process, the amount of grinding on both sides is strictly controlled to ensure that a continuous 430 ferritic stainless steel layer is retained on the blade surface, while multiple layers of 440C are sequentially brought closer to the blade tip to form a gradient support structure.

[0069] The kitchen knife blade prepared in this embodiment has a corrosion-resistant and stable surface layer, a high-hardness and wear-resistant core, and a multi-layered heterogeneous structure that combines good impact resistance and crack resistance. It has balanced performance and good batch stability, making it suitable for mass production of everyday household kitchen knives.

[0070] Example 3 This embodiment uses laser melting deposition technology to prepare a kitchen knife blade with a seven-layer alternating symmetrical sandwich structure. The complete implementation process is as follows: 1. Raw material preparation Gas-atomized 316L austenitic stainless steel powder was selected as the raw material for the strong and tough stainless steel layer, and gas-atomized 440C high-carbon martensitic stainless steel powder was selected as the raw material for the high-carbon martensitic stainless steel layer. The particle size of both powders was screened to be 75-150μm. The powders were vacuum dried before use to remove adsorbed moisture, ensuring powder feeding stability and molten pool forming quality.

[0071] 2. Structural Design The blade design features a seven-layer symmetrical sandwich structure, with the layer sequence being "316L layer / 440C layer / 316L layer / 440C layer / 316L layer / 440C layer / 316L layer". This means four layers of 316L high-strength stainless steel and three layers of 440C high-carbon martensitic stainless steel are stacked alternately, with one more high-strength layer than hard layers, maintaining a completely symmetrical layout in the thickness direction. Each layer is designed to be 0.6mm thick, resulting in a total blade blank thickness of 4.2mm. All layers extend along the length of the blade body, forming a seven-layer stack in the thickness direction of the blade.

[0072] 3. Laser melting deposition forming A coaxial powder-feed laser melting deposition system was used, with 440C high-carbon martensitic stainless steel plate as the prefabricated substrate. Layer-by-layer deposition was performed under an argon protective atmosphere, with the argon gas flow rate set to 15 L / min. The oxygen content in the forming cavity was controlled throughout the process to avoid high-temperature oxidation of the molten pool. The scanning overlap rate was controlled at 45% to ensure the density of intralayer fusion and the strength of interlayer bonding.

[0073] For different materials, corresponding process parameters were matched: when depositing a 440C high-carbon martensitic stainless steel layer, the laser power was set to 1400W, the scanning speed to 9mm / s, and the powder feed rate to 0.6rpm; when depositing a 316L austenitic stainless steel layer, the laser power was set to 1000W, the scanning speed to 10mm / s, and the powder feed rate to 0.8rpm. The layers were deposited sequentially according to a preset seven-layer symmetrical sequence, resulting in a seven-layer alternating layered composite blade blank.

[0074] 4. Integrated heat treatment strengthening After the formed blade blank is separated from the substrate, the surface is cleaned and then subjected to overall heat treatment: first, it is heated to 1000℃ for austenitization treatment, and held for 10 minutes to fully dissolve the carbides and homogenize the structure. Then, it is taken out of the furnace and water-cooled for quenching. After quenching and cooling to room temperature, it is tempered at 200℃, held for 2 hours and then air-cooled. The tempering is performed once.

[0075] Performance testing was conducted after heat treatment: All 440C stainless steel layers in the core underwent complete martensitic transformation, forming a martensitic matrix and dispersed carbide-reinforced structure, with an average microhardness of 652.4 HV, exhibiting excellent wear resistance. The outer and intermediate 316L austenitic stainless steel layers maintained an austenitic structure, with a hardness of 256 HV, demonstrating ample reserves of plasticity and toughness. Smooth transition zones were formed at the interfaces between the 316L and 440C layers, with a hardness of approximately 450 HV, exhibiting a continuous gradient distribution without obvious hardness troughs or interface defects. Scanning electron microscopy observation of the interfaces revealed no microcracks, porosity, or lack of fusion defects, indicating a stable and reliable interlayer metallurgical bond.

[0076] 5. Blade assembly and sharpening finishing The heat-treated seven-layer heterogeneous blade is butt-welded to the 3Cr13 stainless steel blade body using laser welding. After welding, stress relief treatment is performed to eliminate residual welding stress. The entire tool is then ground and finished to correct dimensional deviations caused by forming and heat treatment, improving surface finish. Finally, the blade is sharpened, with precise control over the grinding amount and sharpening depth on both sides to ensure a continuous 316L stainless steel layer on both sides of the blade, while multiple layers of 440C internally progressively advance towards the blade tip to form a gradient rigidity support.

[0077] The seven-layer heterogeneous structure kitchen knife blade prepared in this embodiment has an outer 316L layer with excellent corrosion resistance and impact resistance. The multi-layered alternating heterogeneous interfaces form a multi-level crack-resistant structure, which can effectively deflect and blunt cracks, significantly improving the blade's resistance to chipping and breakage. The core has multiple layers of 440C hardened material that continuously provide high-hardness and wear-resistant support, resulting in excellent edge sharpness retention and balanced overall performance. It is suitable for professional kitchen knives such as chef's knives and slicing knives.

[0078] It should be noted that the transition layer is an optional optimization scheme of the present invention. The above embodiments 1, 2 and 3 are only basic structures without a transition layer. Those skilled in the art can implement the scheme with a transition layer without any doubt based on the teachings of this specification.

[0079] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A high-performance kitchen knife blade with a layered heterogeneous structure, characterized in that, The blade has a layered heterogeneous structure composed of alternating layers of high-carbon martensitic stainless steel and tough stainless steel; the layers of the layered heterogeneous structure extend parallel to the length of the blade and are stacked along the thickness of the blade. The blade adopts a symmetrical sandwich layout, with both sides of the blade thickness direction being high-strength stainless steel layers, and at least one high-carbon martensitic stainless steel layer in the middle; the high-strength stainless steel layer is an austenitic stainless steel layer and / or a ferritic stainless steel layer. The blade is integrally formed using an additive manufacturing process, with metallurgical bonding between the layers.

2. The high-performance kitchen knife blade with a layered heterogeneous structure according to claim 1, characterized in that, The lamellar heterostructure comprises at least three composite layers, and the number of tough stainless steel layers is one more than the number of high-carbon martensitic stainless steel layers.

3. The high-performance kitchen knife blade with a layered heterogeneous structure according to claim 1, characterized in that, The high-carbon martensitic stainless steel is selected from one or more of 440A, 440B, 440C, 9Cr18, 9Cr18Mo, 95Cr18, and 10Cr15CoMoV.

4. The high-performance kitchen knife blade with a layered heterogeneous structure according to claim 1, characterized in that, The austenitic stainless steel is selected from one or more of 301, 304, 304L, 316, and 316L; the ferritic stainless steel is selected from one or more of 409, 410L, 430, 439, and 444.

5. The high-performance kitchen knife blade with a layered heterogeneous structure according to claim 1, characterized in that, The cross-section of the blade after sharpening has a structure with an outer tough stainless steel layer covering it and a core high-carbon martensitic stainless steel layer supporting it; the high-carbon martensitic stainless steel layer has a martensitic strengthening structure and / or a dispersed carbide strengthening structure after heat treatment.

6. The high-performance kitchen knife blade with a layered heterogeneous structure according to claim 1, characterized in that, After heat treatment, a microstructure transition zone is formed at the interface between the high-carbon martensitic stainless steel layer and the tough stainless steel layer. The microstructure transition zone is a recrystallized equiaxed crystal structure.

7. The high-performance kitchen knife blade with a layered heterogeneous structure according to claim 1, characterized in that, The thickness of a single layer of the lamellar heterostructure is 20 μm to 1.5 mm.

8. The high-performance kitchen knife blade with a layered heterogeneous structure according to claim 7, characterized in that, The thickness of a single layer of the lamellar heterostructure is 30 μm to 500 μm.

9. The high-performance kitchen knife blade with a layered heterogeneous structure according to claim 1, characterized in that, After sharpening, the cutting edge angle is 10° to 40°.

10. The high-performance kitchen knife blade with a layered heterogeneous structure according to claim 1, characterized in that, A transition layer with a gradual change in composition is provided between the high-carbon martensitic stainless steel layer and the tough stainless steel layer. The transition layer is used to reduce interlayer stress concentration.

11. A layered heterogeneous kitchen knife, characterized in that, The invention includes a blade, a handle, and a high-performance kitchen knife blade with a layered heterogeneous structure as described in any one of claims 1 to 10; the blade is fixed to the cutting edge region of the blade by welding or mechanical fitting, or the blade is formed in situ in the cutting edge region of the blade by additive manufacturing and forms an integral structure with the blade.

12. The layered heterogeneous structure kitchen knife according to claim 11, characterized in that, The blade is made of one or more of the following materials: austenitic stainless steel, ferritic stainless steel, martensitic stainless steel, low alloy steel, and composite steel.

13. A method for preparing a high-performance kitchen knife blade with a layered heterogeneous structure as described in claim 1, characterized in that, Includes the following steps: Step 1. Design a layered heterogeneous structure for the blade area. The layered heterogeneous structure is composed of alternating layers of high-carbon martensitic stainless steel and high-toughness stainless steel. The layers of the layered heterogeneous structure extend parallel to the length of the blade and are stacked along the thickness of the blade. Step 2. Prepare the blade blank using additive manufacturing technology. Use a symmetrical sandwich layout for layer-by-layer deposition so that the two sides of the blade blank in the thickness direction are strong and tough stainless steel layers, and at least one layer of high carbon martensitic stainless steel is set in the middle to obtain a layered composite blade blank with alternating "hard-tough" properties. Step 3. Integrated heat treatment strengthening: The layered composite blade blank is subjected to an integrated heat treatment, which includes at least austenitization, quenching and tempering. The heat treatment is carried out in accordance with the strengthening regime of high carbon martensitic stainless steel, so as to promote the full martensitic transformation of the high carbon martensitic stainless steel layer and obtain a dispersed carbide strengthening structure. At the same time, the tough stainless steel layer is recrystallized and the structure is homogenized, resulting in a heterogeneous blade with gradient properties. Step 4. Connect the heat-treated blade blank to the blade body to obtain a combined tool blank; or, directly prepare the blade blank in situ by additive manufacturing in a predetermined cutting area of ​​the blade body, so that the blade blank and the blade body form an integral tool blank. Step 5. Grind, finish and sharpen the knife blank obtained in Step 4 to obtain a layered heterogeneous kitchen knife. After sharpening, the outermost exposed layer of the blade is a tough stainless steel layer, and the core of the blade is a high-carbon martensitic stainless steel layer.

14. The preparation method according to claim 13, characterized in that, The additive manufacturing technology is laser melting deposition technology, laser powder bed melting technology, or a combination of the two.

15. The preparation method according to claim 13, characterized in that, In step 2, the number of layers of the tough stainless steel layer is one more than the number of layers of the high-carbon martensitic stainless steel layer.

16. The preparation method according to claim 13, characterized in that, In step 3, the austenitizing treatment temperature is 960℃~1100℃, and after holding at this temperature, oil quenching, gas quenching, vacuum quenching, or salt bath quenching are performed; the tempering treatment temperature is 150℃~300℃, and the tempering time is 1h~4h.

17. The preparation method according to claim 16, characterized in that, In step 3, after quenching, a cryogenic treatment is also included; the temperature of the cryogenic treatment is -80℃ to -196℃, and the treatment time is 0.5h to 24h.

18. The preparation method according to claim 13, characterized in that, In step 2, a transition layer with a gradually changing composition is deposited between the high-carbon martensitic stainless steel layer and the tough stainless steel layer to reduce interlayer stress concentration.

Images