Blade, preparation method thereof and food processor

Abstract

The invention provides a blade and a preparation method thereof and a food processor, and the preparation method of the blade comprises the following steps: in a nitrogen-containing environment, smelting a metal raw material to obtain a metal solution; preparing the metal solution into a blank body; and preparing the blade from the blank. According to the preparation method of the blade, the metal raw materials are smelted in the nitrogen-containing environment, so that the nitrogen element can be uniformly dispersed and distributed in the metal solution, the strengthening and toughening and corrosion resisting effects can be fully exerted, and it is guaranteed that the blade is not collapsed, turned and fractured when the blade whips hard objects; and when the blade material is in contact with a humid environment and complex food materials for a long time, rusting, corrosion and cracking are avoided.

Description

Technical Field

[0001] The present invention relates to the technical field of kitchen appliances, and more specifically, to a blade, a preparation method thereof, and a food processor. Background Art

[0002] With the continuous improvement of people's living standards, small household appliances such as blenders, represented by wall breakers, are becoming increasingly common. The core component of a wall breaker is the wall breaker blade. If the blade material is not up to standard, there will be risks of blade chipping, breaking, deformation, and corrosion during operation, bringing a very bad user experience to users. At the same time, the poor crushing effect and high noise of wall breakers have always been the core pain points. Increasing the strength and hardness of the blade can effectively improve the crushing ability of the stirring system, help to grind the ingredients finer, and is also beneficial to reducing the motor speed and controlling the noise value.

[0003] However, traditional high-strength materials are generally not corrosion-resistant and there is a risk of rust when used as blade materials. In addition, the strength and plastic toughness of materials often restrict each other. Increasing strength often comes with an increase in brittleness. And the brittleness of the material will not only increase the potential risk of blade breakage when stirring ingredients, but also limit the bending angle of the wall breaker blade, affecting the structure design of the blade and even the entire stirring system.

[0004] Therefore, it is an urgent technical problem to be solved at present to invent a wall breaker blade with good performance in terms of strength, hardness, plastic toughness, and corrosion resistance. Summary of the Invention

[0005] The present invention aims to solve at least one of the technical problems existing in the prior art or related technologies.

[0006] The first aspect of the present invention provides a preparation method of a blade.

[0007] The second aspect of the present invention provides a blade.

[0008] The third aspect of the present invention provides a food processor.

[0009] The first aspect of the present invention provides a preparation method of a blade. The blade contains nitrogen, and the mass percentage of nitrogen in the blade is greater than or equal to 0.06% and less than or equal to 0.5%. The content of nitrogen at any position in the blade is greater than or equal to m(1 - 5%) and less than or equal to m(1 + 5%), where m is the mass percentage of nitrogen in the blade accounting for the total mass of the blade. The preparation method of the blade includes: smelting a metal raw material in a nitrogen-containing environment to obtain a metal solution; preparing the metal solution into a blank; and preparing the blade through the blank.

[0010] The preparation method of the blade provided by the present invention smelts the metal raw material in a nitrogen-containing environment, so that nitrogen elements can be evenly and dispersedly distributed in the metal solution. For the blade prepared by this method, the nitrogen element content at each position in the blade is greater than or equal to m(1 - 5%) and less than or equal to m(1 + 5%). That is, the nitrogen element content at each position in the blade is basically the same, and the nitrogen element is evenly and dispersedly distributed in the blade. Therefore, the strengthening and toughening and corrosion resistance effects can be fully exerted, ensuring that the blade does not break, curl, or crack when beating hard objects, and does not rust or corrode and crack when the blade material is in long-term contact with a humid environment and complex food materials.

[0011] Further, when more than 0.06% of nitrogen elements are evenly and dispersedly distributed in the material matrix, the strengthening and toughening and corrosion resistance effects can be fully exerted. When the nitrogen element content in the nitrogen-containing martensitic stainless steel is between 0.06% and 0.2%, although the addition of nitrogen elements has a positive effect, the effect of suppressing intergranular corrosion and exerting the strengthening effect of N elements by adding N elements is limited. On the contrary, if too much nitrogen element is added, when it exceeds 0.5%, element segregation is likely to occur, which will instead affect the comprehensive performance of the material. Optionally, the mass percentage of nitrogen element in the blade is greater than or equal to 0.2% and less than or equal to 0.5%, such as 0.2%, 0.3%, 0.4%, or 0.5%.

[0012] In some technical solutions, optionally, the step of smelting the metal raw material in a nitrogen-containing environment to obtain a metal solution includes: adding a nitride to the metal raw material for smelting to obtain a metal solution.

[0013] In this technical solution, when smelting the metal raw material, adding a nitride to the metal raw material can make the nitrogen element fully dissolve into the metal solution. Therefore, the strengthening and toughening and corrosion resistance effects can be fully exerted, ensuring that the blade does not break, curl, or crack when beating hard objects, and does not rust or corrode and crack when the blade material is in long-term contact with a humid environment and complex food materials.

[0014] In some technical solutions, optionally, the nitride includes at least one of the following or a combination thereof: silicon nitride, chromium nitride, manganese nitride.

[0015] In this technical solution, adding nitrides such as silicon nitride, chromium nitride, and manganese nitride to the metal raw material can make the nitrogen element better dissolve into the metal solution.

[0016] In some technical solutions, optionally, the step of smelting the metal raw material in a nitrogen-containing environment to obtain a metal solution includes: smelting the metal raw material in a nitrogen environment to obtain a metal solution, and in the nitrogen environment, the nitrogen pressure is greater than the target pressure.

[0017] In this technical solution, under the condition of 1 Bar (1 atmospheric pressure, or standard atmospheric pressure), the solubility of nitrogen in the Fe-Cr alloy system steel is very low, and the uniform distribution is not good. Gas pores are easily generated during the solidification process. Under the condition of high nitrogen pressure, the solubility of nitrogen will increase with the increase of nitrogen partial pressure. Therefore, the present invention controls the nitrogen pressure to be greater than the target pressure, and the target pressure is greater than 1 Bar, which can improve the solubility and uniform distribution degree of nitrogen element in the blade, thus improving the comprehensive performance of the blade.

[0018] In some technical solutions, optionally, the target pressure is greater than or equal to 10 Bar; or the target pressure is greater than or equal to 20 Bar and less than or equal to 30 Bar.

[0019] In this technical solution, by controlling the range of nitrogen pressure, the solubility of nitrogen element in the raw material can be further improved, so that the nitrogen element is uniformly distributed in the blade, the nitrogen content is increased, and the comprehensive performance of the blade is further improved.

[0020] In some technical solutions, optionally, the step of smelting metal raw materials in a nitrogen-containing environment to obtain a metal solution includes: smelting metal raw materials in a nitrogen-containing environment through a pressurized electroslag remelting reaction furnace to obtain a metal solution.

[0021] In this technical solution, pressurized electroslag remelting can not only improve the solubility of nitrogen in the melt, but also contribute to the homogenization of nitrogen, forming a uniform dispersion distribution effect in the alloy.

[0022] In some technical solutions, optionally, the step of preparing a blade from a blank includes: hot forging the blank, and then hot rolling to form a first plate with a first thickness; performing multi-pass cold rolling on the first plate to obtain a second plate with a second thickness, the second thickness being less than the first thickness; heat treating the second plate; and processing the heat-treated second plate into a blade.

[0023] In this technical solution, after the blank is prepared, the blank is hot forged at a hot forging temperature of 900 °C to 1100 °C, and then hot rolled to form a first plate with a first thickness; the first thickness is 5 mm to 15 mm, for example 10 mm. Multi-pass cold rolling is performed on the first plate to obtain a second plate with a second thickness, the second thickness being 1 mm to 2 mm, for example 1.5 mm. The second plate is heat treated; and the heat-treated second plate is processed into a blade. The present invention processes the blank through hot forging, hot rolling and multi-pass cold rolling, which can further achieve the homogenization of nitrogen and form a uniform dispersion distribution effect in the alloy.

[0024] In some technical solutions, optionally, when the blank is hot rolled, the hot rolling temperature is greater than or equal to 900°C and less than or equal to 1100°C; when the first plate is subjected to multiple cold rolling processes, the cold rolling temperature is greater than or equal to 0°C and less than or equal to 200°C.

[0025] In this technical solution, by controlling the hot rolling and cold rolling temperatures, the structural composition can be made more uniform, the uniformity of the nitrogen element can be further improved, and the comprehensive performance of the blade can be improved.

[0026] In some technical schemes, optionally, the step of heat treating the second plate includes: performing solution treatment, cryogenic treatment and tempering treatment on the second plate, wherein, during the solution treatment, the temperature is greater than or equal to 1000°C and less than or equal to 1050°C, and the insulation time is greater than or equal to 1h and less than or equal to 2h; during the cryogenic treatment, the temperature is greater than or equal to minus 80°C and less than or equal to minus 70°C, and the insulation time is greater than or equal to 1h and less than or equal to 2h; the tempering temperature is greater than or equal to 150°C and less than or equal to 200°C, and the insulation time is greater than or equal to 2h and less than or equal to 8h.

[0027] In this technical solution, by controlling the parameters of the heat treatment of the second plate, the organizational composition can be made more uniform, the uniformity of the nitrogen element can be further improved, and the comprehensive performance of the blade can be improved. Optionally, the solution treatment temperature is 1000°C, 1020°C, 1040°C, and the insulation time is 1h, 1.5h or 2h. Optionally, the cryogenic treatment temperature is minus 80°C, minus 70°C, and the insulation time is 1h, 1.5h or 2h. Optionally, the tempering treatment temperature is 150°C, 170°C, 190°C, and the insulation time is 2h, 4h, 6h or 8h.

[0028] In some technical solutions, optionally, the first end of the blade is a mounting end, and the preparation method further includes: bending the second end of the blade from one side relative to the mounting end toward the other side of the blade, with a bending angle of α, and -30°≤α≤30°.

[0029] In this technical solution, generally speaking, it is difficult to take both hardness and plastic toughness into account, so for general high-hardness alloys, their plastic toughness is generally poor, which is not only reflected in the easy collapse of the blade during whipping, but also an important point is that the bending of the blade will be limited, because materials with poor plastic toughness will soon crack when bent, and then break due to crack expansion. However, the blade prepared by the present invention, due to the uniform distribution of nitrogen, not only ensures high hardness but also takes into account good plastic toughness, and supports a wider range of bending angles, which can reach 20°, 25° or 30°. Since the food is in motion during the crushing process, the blade prepared by the present invention has a larger bending angle, which can increase the scanning range of the blade, so the crushing effect on the food is better, and the crushing efficiency is improved.

[0030] In some technical solutions, optionally, the method for preparing the blade further includes: polishing the blade.

[0031] In this technical solution, by polishing the blade, the smoothness of the blade surface can be further improved, and the cutting performance can be enhanced.

[0032] In some technical solutions, optionally, the metal raw material is a martensitic stainless steel material.

[0033] In this technical solution, in the present invention, the blade prepared from the martensitic stainless steel material has excellent corrosion resistance and good plasticity, and there are no rust spots visible to the naked eye on the blade surface after 96 hours of neutral salt spray corrosion.

[0034] The second aspect of the present invention provides a blade, particularly a blade for a wall breaker, aiming to improve the crushing effect of the wall breaker and enhance the edible texture of the crushed food materials. The blade provided by the present invention is prepared by the method for preparing the blade provided in the first aspect of the present invention.

[0035] In some technical solutions, optionally, the blade includes a cutting edge, and the width of the cutting edge is L, where 3 mm ≤ L ≤ 7 mm.

[0036] In this technical solution, the width range of the cutting edge is 3 mm ≤ L ≤ 7 mm. When the width of the cutting edge is less than 3 mm, the cutting edge is too narrow to effectively crush hard food materials such as lotus seeds. If the width of the cutting edge is too wide, the blade material cannot provide effective strength support for the wide cutting edge, and there is a high risk of plastic deformation of the cutting edge after multiple stir-fryings of dry and hard food materials (such as 300 times of dry soybeans). Generally, the width of the cutting edge of conventional austenitic stainless steel (such as 301) is set within 5 mm, and there is a risk of plastic deformation when it exceeds 5 mm. Due to its high strength and hardness, the nitrogen-containing martensitic stainless steel in the present invention can enlarge the width of the cutting edge to within the range of ≤ 7 mm. Optionally, the width of the cutting edge of the present invention is 5 mm ≤ L ≤ 7 mm. For example, the width of the cutting edge is 5 mm, 6 mm or 7 mm.

[0037] In some technical solutions, optionally, the minimum thickness of the cutting edge is W, where 1 μm ≤ W ≤ 100 μm.

[0038] In the technical solution, the minimum thickness of the blade is W, wherein 1um≤W≤100um, optionally, 1um≤W≤10um. When 1um≤W≤10um, if the hardness is lower than 50HRC, especially lower than 45HRC, it is very easy to be worn due to insufficient wear resistance or insufficient strength and hardness, resulting in the blade curling, which causes the whipping effect of the wall-breaking machine blade to be significantly deteriorated after a period of use, and is even worse than the effect of normal sharpening (30um≤W≤100um). The present invention can greatly improve the hardness of the blade by uniformly distributing nitrogen, and the maximum hardness can reach 65HRC, so the minimum thickness of the blade of the present invention can be set between 1um and 10um. For example, the minimum thickness of the blade is 4um, 5um or 6um.

[0039] In some technical solutions, optionally, when the hardness value of the blade is greater than or equal to 50HRC and less than or equal to 58HRC, 4um<W≤10um; when the hardness value of the blade is greater than 58HRC and less than or equal to 65HRC, 1um≤W≤4um.

[0040] In this technical solution, the present invention can greatly improve the hardness of the blade by uniformly distributing nitrogen elements. The greater the hardness value, the smaller the minimum thickness W of the blade can be set, further improving the cutting ability.

[0041] In some technical solutions, optionally, the blade includes a blade, the blade is a straight blade, and the angle between the upper surface and the lower surface of the blade is a first angle ε1, wherein 17°<ε1≤28°.

[0042] In this technical solution, the blade of the present invention is a straight blade, that is, the blade is formed in one process, which can improve the processing efficiency. Furthermore, the angle between the upper surface and the lower surface of the blade is a first angle ε1, wherein 17°<ε1≤28°. This is because when ε≤17°, the angle is too small. When the blade area extends outward from the tip to 0.5mm, the distance between the upper and lower surfaces of the blade (i.e., the thickness) is only 150um, which causes the front end of the blade tip to deform more easily when the blade is whipping dry and hard ingredients, which will affect the blade's long-lasting crushing effect. If ε1≥28°, the angle will be too large, which will reduce the crushing effect.

[0043] In some technical schemes, optionally, the blade includes a first section and a second section arranged in stages, the connection between the first section and the second section is a target point, the first section is from the starting point of the blade to the target point, and the second section is from the target point to the end point of the blade, the angle between the upper surface and the lower surface of the first section is a second angle ε2, and the angle between the upper surface and the lower surface of the second section is a third angle θ, 12°≤ε2≤28°, 40°≤θ≤60°.

[0044] In this technical solution, the blade edge includes a first section and a second section arranged in a stepped manner. The edge-opening method of the stepped blade can further expand the range of the included angle ε. Since the angle of θ is large, it can compensate for the disadvantage of insufficient support caused by the overly thin front end of the blade tip when the edge is opened once with ε ≤ 17°, so that the range of ε is expanded to 12° ≤ ε ≤ 28°.

[0045] In some technical solutions, optionally, 12° ≤ ε2 < 17°.

[0046] In some technical solutions, optionally, when 12° ≤ ε2 < 17°, 1 / 5 ≤ ε2 / θ ≤ 3 / 10; when 17° ≤ ε2 ≤ 28°, 1 / 3 ≤ ε2 / θ ≤ 2 / 3.

[0047] In this technical solution, when the stepped edge is opened, there is a proportional relationship between ε2 and θ. When 12° ≤ ε2 < 17°, it is necessary to increase the angle of the secondary edge-opening θ to ensure the stiffness of the blade tip and ensure that the front end of the thin-edge blade tip is not easily curled. At this time, the ratio range of ε2 / θ should be set smaller, that is, the value of θ is higher and the protection effect is better; when 17° ≤ ε2 ≤ 28°, the entire edge-opening area of the blade has a certain thickness, which is beneficial to ensuring the rigidity of the front end of the blade tip. At this time, it is not necessary to set the proportional relationship of ε2 / θ too small, because when the plastic deformation of the blade tip can be ensured, the larger the value of θ, the more it will affect the cutting effect of the blade tip. At this time, the angle of the secondary edge-opening θ needs to be set smaller. Generally speaking, when the included angle ε is larger, the one-time edge-opening method is more suitable.

[0048] In some technical solutions, optionally, the thickness of the blade at the target point is greater than or equal to 100 um and less than or equal to 500 um.

[0049] In this technical solution, by appropriately selecting the stepped point of the stepped blade edge, the strength of the blade edge can be further improved.

[0050] In some technical solutions, optionally, the first end of the blade is the installation end, the second end of the blade bends from one side of the installation end to the other side of the blade, and a fifth angle α is set between the upper surface of the first end and the upper surface of the second end, and -30° ≤ α ≤ 30°.

[0051] In this technical solution, generally speaking, since it is difficult to balance hardness and plasticity-toughness, for general high-hard alloys, their plasticity-toughness is generally poor. This is not only reflected in the fact that the blade is prone to chipping during whipping, but also importantly, the bending of the blade is restricted because materials with poor plasticity-toughness will quickly develop cracks during bending and will then break due to crack propagation. However, for the blade prepared by the present invention, due to the uniform distribution of nitrogen elements, while ensuring high hardness, it also takes into account good plasticity-toughness, supports a larger range of bending angles, can meet the condition of bending 30°, and the larger the ultimate bending angle of the blade material, the more conducive it is to the flexible design of the blade and can meet more whipping usage scenarios. Optionally, 10° ≤ α ≤ 30°, for example, 20°, 25° or 30°.

[0052] In some technical solutions, optionally, the total mass percentage of nitrogen element and carbon element in the blade is greater than or equal to 0.3% and less than or equal to 0.8%.

[0053] In this technical solution, controlling the sum of the mass percentages of nitrogen element and carbon element to be greater than or equal to 0.3% and less than or equal to 0.8% can increase the content of nitrogen element and carbon element and improve the strength of the blade. However, the total mass of nitrogen element and carbon element should not be too large, otherwise it will reduce the comprehensive performance of the blade.

[0054] The third aspect of the present invention provides a food processor, including the blade provided by any one of the technical solutions of the second aspect of the present invention.

[0055] The additional aspects and advantages according to the present invention will become apparent in the following description section or be learned through the practice according to the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0056] The above and / or additional aspects and advantages according to the embodiments of the present invention will become apparent and be readily understood from the description of the embodiments in conjunction with the following drawings, wherein:

[0057] Figure 1 One of the schematic flowcharts showing the preparation method of the blade provided by the embodiment of the present invention;

[0058] Figure 2 Another schematic flowchart showing the preparation method of the blade provided by the embodiment of the present invention;

[0059] Figure 3 The cross-sectional view of the embryo during the preparation process of the blade provided by the embodiment of the present invention;

[0060] Figure 4 The schematic structural diagram of the food processor provided by the embodiment of the present invention;

[0061] Figure 5Shows one of the schematic structural diagrams of the blade provided by the embodiment of the present invention;

[0062] Figure 6 Shows another schematic structural diagram of the blade provided by the embodiment of the present invention;

[0063] Figure 7 Shows yet another schematic structural diagram of the blade provided by the embodiment of the present invention;

[0064] Figure 8 Shows the fourth schematic structural diagram of the blade provided by the embodiment of the present invention.

[0065] Among them, Figure 4 、 Figure 7 and Figure 8 The corresponding relationship between the component names and labels is as follows:

[0066] 1 food processor, 12 blade, 122 blade edge, 1222 starting point, 1224 ending point, 1226 target point, 124 rib. Detailed implementation manners

[0067] In order to more clearly understand the above aspects, features and advantages of the embodiments according to the present invention, the embodiments according to the present invention will be further described in detail below in conjunction with the drawings and specific implementation manners. It should be noted that, without conflict, the embodiments of the present application and the features in the embodiments may be combined with each other.

[0068] Many specific details are set forth in the following description in order to provide a thorough understanding of the embodiments according to the present invention. However, the embodiments according to the present invention may also be implemented in other ways different from those described herein. Therefore, the scope of protection of the embodiments according to the present invention is not limited by the specific embodiments disclosed below.

[0069] Embodiment 1

[0070] As Figure 1 shown, this embodiment provides a method for preparing a blade. The mass percentages (wt.%) of the chemical components of the blade prepared in this embodiment are as follows: N: 0.2%, Cr: 14%, Ni: 0.5%, Mo: 1%, Si: 0.5%, Mn: 0.5%, C: 0.2%, S: 0.02%, P: 0.02%, Fe: balance. The method for preparing the blade includes the following steps:

[0071] S102: Put each alloy into an induction furnace for melting according to the above mass percentages. After melting, secondary refining is carried out by ladle furnace refining (LF) + vacuum degassing (VD) to obtain an alloy ingot;

[0072] S104: Using a pressurized electroslag remelting (PESR) reactor, add silicon nitride, chromium nitride, manganese nitride, etc. into the remelting slag, and simultaneously introduce nitrogen gas. The nitrogen partial pressure in the melting chamber is 10 Bar, so that nitrogen elements are fully dissolved into the solution, and a blank is obtained after cooling and forming;

[0073] Among them, pressurized electroslag remelting can not only increase the solubility of nitrogen in the melt, but also help to achieve the homogenization of nitrogen, forming a uniform and dispersed distribution effect within the alloy;

[0074] S106: Hot forge the blank at a forging temperature of 900 °C, and then hot roll it into a sheet with a thickness of 10 mm;

[0075] S108: Cold roll the hot-rolled sheet for 3 passes, and finally roll it into a thin sheet with a thickness of 1.5 mm;

[0076] S110: Heat-treat the cold-rolled thin sheet. The heat treatment process is solution treatment + cryogenic treatment + tempering. Among them, the solution treatment temperature is 1000 °C and the holding time is 1 h; the cryogenic treatment temperature is -73 °C and the holding time is 1 h; the tempering temperature is 150 °C and the holding time is 4 h;

[0077] S112: Semi-finish the heat-treated thin sheet to the specified size and accuracy according to the drawing requirements by stamping and wire cutting, then edge the blade and bend it at an angle, and then electrolytically polish it to obtain the blade.

[0078] In the blade prepared by the blade preparation method provided in this embodiment, the distribution of nitrogen elements is uniform. Among them, after the blank prepared in step S104 is vertically cut at a position 5 cm away from the end, no less than 10 points are sampled in any area from the surface to the core (as Figure 3 shown, each small circle represents a sampling point). The nitrogen content of the sample at each point is measured using a nitrogen and oxygen analyzer, and the deviation between the test results of each point does not exceed 5%. It can be seen that in the blade smelted by the present invention, the nitrogen elements have a uniform and dispersed distribution effect, that is, from the material surface to the material core, the content of nitrogen elements is basically the same, which makes the present invention essentially different from the nitriding process. Nitriding is a chemical heat treatment process that produces active nitrogen atoms by decomposing ammonia gas, and makes the nitrogen atoms adsorb to the surface of the workpiece matrix and diffuse into the shallow layer of the workpiece. It is a surface treatment method. After nitriding, the nitrogen atoms can only be enriched in a very thin layer area on the surface of the matrix, and the nitrogen atom concentrations at different positions after nitriding are inconsistent. The closer to the surface, the higher the nitrogen atom concentration, and the farther away from the surface layer, the lower the concentration until the nitrogen atoms can no longer penetrate. Generally speaking, the nitriding layer depth does not exceed 0.6 mm - 0.7 mm.

[0079] Next, perform performance tests such as hardness and corrosion resistance on the blade prepared in this embodiment and the conventional blade:

[0080] The parameters of this embodiment, the composition and related parameters of the conventional blade are as follows:

[0081] This embodiment: Nitrogen-containing stainless steel, the width of the upper and lower surfaces at the thinnest position of the blade edge is 5um, and it is bent by 25°.

[0082] Comparative Example 1: 420 stainless steel, the width of the upper and lower surfaces at the thinnest position of the blade edge is 5um, and it is bent by 25°.

[0083] Comparative Example 2: 420 stainless steel, the width of the upper and lower surfaces at the thinnest position of the blade edge is 5um, and it is bent by 5°.

[0084] Comparative Example 3: 420 stainless steel, the width of the upper and lower surfaces at the thinnest position of the blade edge is 5um, and it is bent by 5°. The surface of the blade is subjected to anti-corrosion passivation treatment.

[0085] Comparative Example 4: 301 stainless steel, the width of the upper and lower surfaces at the thinnest position of the blade edge is 5um, and it is bent by 25°.

[0086] Comparative Example 5: 301 stainless steel, the width of the upper and lower surfaces at the thinnest position of the blade edge is 50um, and it is bent by 25°.

[0087] The test methods are as follows:

[0088] 1. Salt spray test: According to GB / T10125 "Artificial atmosphere corrosion test - Salt spray test", place the finished product samples in a neutral salt spray test chamber at 35°C ± 2°C, continuously spray with a sodium chloride solution with a concentration of 5%, take out and rinse with water and air dry every 12 hours, and visually inspect the surface quality.

[0089] 2. Hardness test: Use a microhardness tester to test the coating hardness. Randomly select five positions on the sample surface for testing. Use a load of 0.2 kgf and a diamond square pyramid with a vertex angle of 136° to press into the material surface and hold the pressure for 30 seconds. Divide the load value by the surface area of the material indentation pit to obtain the Vickers hardness value.

[0090] 3. Particle size test: Use a Beckman Coulter LS13-320 laser particle size analyzer to detect the sample based on the physical phenomenon that particles can cause laser scattering. The particle size measurement results of the sample are analyzed by a computer.

[0091] The performance test results of the blades in this embodiment and different comparative examples are shown in Table 1 below:

[0092]

[0093] Table 1

[0094] Among them:

[0095] 1. The time of this neutral salt spray test is 96 hours.

[0096] 2. The state after the blade is used refers to the test after whipping dry soybeans 300 times.

[0097] 3. The food material for particle size test comes from the soy milk made by using the thick soy milk function file after adding 100 g of dry soybeans + 1200 g of water in the company's MJ-BL10SJ85 wall breaker as the test sample.

[0098] It can be seen from the examples and Comparative Examples 1 to 5 that the nitrogen-containing stainless steel has high hardness, good anti-bending ability, corrosion resistance meeting the product requirements, and excellent ability to crush food materials. Moreover, after the edge area is ground into a thin edge, it is not easy to wear and curl. It is reflected that the particle size of the soy milk does not increase significantly after crushing dry soybeans 300 times; 420 martensitic stainless steel also has relatively high hardness, but its plasticity, toughness and corrosion resistance are not good. It will break when bent at 25° (Comparative Example 1) and cannot pass the neutral salt spray test (Comparative Example 2). By making a passivation film on the surface of the 420 blade, the corrosion resistance of the blade in the initial state can be significantly improved. However, after repeatedly whipping hard objects (such as 300 times of dry soybeans), the surface passivation film will be damaged and the corrosion resistance problem cannot be fundamentally solved (Comparative Example 3); the 301 blade is relatively soft. If a 5-μm thin edge is ground, although the initial cutting ability is very good, the tip of the blade is easy to wear and curl after long-term use. It is manifested that there is an obvious difference in the particle size of the soy milk made in the initial state and the particle size of the soy milk made after whipping dry soybeans 300 times, and the particle size increases very significantly (Comparative Example 4). When the 301 blade has a 50-μm edge, due to the relatively thick edge, the particle size of the soy milk after multiple whippings does not increase significantly, but the soy milk can never be ground fine, and the resulting soy milk will have an obvious sense of residue and poor taste (Comparative Example 5).

[0099] As Figure 2 shown, this embodiment provides a method for preparing a blade, including the following steps:

[0100] S202: Smelt the metal raw material in a nitrogen-containing environment to obtain a metal solution;

[0101] S204: Prepare the metal solution into a blank; prepare the blade from the blank.

[0102] The preparation method of the blade provided by the present invention smelts metal raw materials in a nitrogen-containing environment, so that nitrogen elements are uniformly and dispersedly distributed in the metal solution. For the blade prepared by this method, the nitrogen element content at each position in the blade is greater than or equal to m(1 - 5%) and less than or equal to m(1 + 5%), that is, the nitrogen element content at each position in the blade is basically the same, and the nitrogen elements are uniformly and dispersedly distributed in the blade. Therefore, the strengthening and toughening and corrosion resistance effects can be fully exerted, ensuring that the blade does not break, curl or crack when beating hard objects, and does not rust or corrode and crack when the blade material is in long-term contact with a humid environment and complex food ingredients.

[0103] Furthermore, when more than 0.06% of nitrogen elements are uniformly and dispersedly distributed in the material matrix, the strengthening and toughening and corrosion resistance effects can be fully exerted. When the nitrogen element content in nitrogen-containing martensitic stainless steel is between 0.06% - 0.2%, although the addition of nitrogen elements has a positive effect, the effect of suppressing intergranular corrosion and exerting the strengthening effect of N elements by adding N elements is limited. On the contrary, if too much nitrogen element is added, when it exceeds 0.5%, element segregation is likely to occur, which will instead affect the comprehensive performance of the material. Optionally, the mass percentage of nitrogen element in the blade is greater than or equal to 0.2% and less than or equal to 0.5%, such as 0.2%, 0.3%, 0.4% or 0.5%.

[0104] In some embodiments, optionally, the step of smelting metal raw materials in a nitrogen-containing environment to obtain a metal solution includes: adding a nitride to the metal raw materials for smelting to obtain a metal solution.

[0105] In this embodiment, when smelting the metal raw materials, adding a nitride to the metal raw materials can make the nitrogen elements fully dissolve into the metal solution. Therefore, the strengthening and toughening and corrosion resistance effects can be fully exerted, ensuring that the blade does not break, curl or crack when beating hard objects, and does not rust or corrode and crack when the blade material is in long-term contact with a humid environment and complex food ingredients.

[0106] In some embodiments, optionally, the nitride includes at least one of the following or a combination thereof: silicon nitride, chromium nitride, manganese nitride.

[0107] In this embodiment, adding nitrides such as silicon nitride, chromium nitride, and manganese nitride to the metal raw materials can make the nitrogen elements better dissolve into the metal solution.

[0108] In some embodiments, optionally, the step of smelting metal raw materials in a nitrogen-containing environment to obtain a metal solution includes: smelting the metal raw materials in a nitrogen environment to obtain a metal solution, and in the nitrogen environment, the nitrogen pressure is greater than the target pressure.

[0109] In this embodiment, under the condition of 1 Bar (1 atmospheric pressure, or standard atmospheric pressure), the solubility of nitrogen in the Fe-Cr alloy system steel is very low, and the uniform distribution is not good. Gas pores are likely to be generated during the solidification process. Under the condition of high nitrogen pressure, the solubility of nitrogen will increase with the increase of nitrogen partial pressure. Therefore, by controlling the nitrogen pressure of the present invention to be greater than the target pressure, the solubility and uniform distribution degree of nitrogen element in the blade can be improved, thus improving the comprehensive performance of the blade.

[0110] In some embodiments, optionally, the target pressure is greater than or equal to 10 Bar; or the target pressure is greater than or equal to 20 Bar and less than or equal to 30 Bar.

[0111] In this embodiment, by controlling the range of nitrogen pressure, the solubility of nitrogen element in the raw material can be further improved, so that the nitrogen element is uniformly distributed in the blade, the nitrogen content is increased, and the comprehensive performance of the blade is further improved.

[0112] In some embodiments, optionally, the step of smelting the metal raw material in a nitrogen-containing environment to obtain a metal solution includes: smelting the metal raw material in a nitrogen-containing environment through a pressurized electroslag remelting reaction furnace to obtain a metal solution.

[0113] In this embodiment, pressurized electroslag remelting can not only increase the solubility of nitrogen in the melt, but also contribute to the homogenization of nitrogen, forming a uniform dispersion distribution effect in the alloy.

[0114] In some embodiments, optionally, the steps of preparing the blade from the blank include: hot forging the blank, and then hot rolling to form a first sheet with a first thickness; performing multi-pass cold rolling on the first sheet to obtain a second sheet with a second thickness, where the second thickness is less than the first thickness; performing heat treatment on the second sheet; and processing the heat-treated second sheet into a blade.

[0115] In this embodiment, after the blank is prepared, hot forging is performed on the blank at a hot forging temperature of 900 °C to 1100 °C, and then hot rolling is performed to form a first sheet with a first thickness; the first thickness is 5 mm to 15 mm, for example 10 mm. Multi-pass cold rolling is performed on the first sheet to obtain a second sheet with a second thickness, where the second thickness is 1 mm to 2 mm, for example 1.5 mm. Heat treatment is performed on the second sheet; and the heat-treated second sheet is processed into a blade.

[0116] In some embodiments, optionally, when hot rolling the blank, the hot rolling temperature is greater than or equal to 900 °C and less than or equal to 1100 °C, for example, 900 °C, 1000 °C or 1100 °C; when performing multi-pass cold rolling on the first sheet, the cold rolling temperature is greater than or equal to 0 °C and less than or equal to 200 °C, for example, 40 °C, 80 °C, 140 °C or 160 °C.

[0117] In this embodiment, by controlling the hot rolling and cold rolling temperatures, the structure composition can be made more uniform, the uniformity of the nitrogen element can be further improved, and the comprehensive performance of the blade can be improved.

[0118] In some embodiments, optionally, the step of heat treating the second plate includes: performing solution treatment, cryogenic treatment and tempering treatment on the second plate, wherein, during the solution treatment, the temperature is greater than or equal to 1000°C and less than or equal to 1050°C, and the insulation time is greater than or equal to 1h and less than or equal to 2h; during the cryogenic treatment, the temperature is greater than or equal to minus 80°C and less than or equal to minus 70°C, and the insulation time is greater than or equal to 1h and less than or equal to 2h; the tempering temperature is greater than or equal to 150°C and less than or equal to 200°C, and the insulation time is greater than or equal to 2h and less than or equal to 8h.

[0119] In this embodiment, by controlling the parameters of the heat treatment of the second plate, the organizational composition can be made more uniform, the uniformity of the nitrogen element can be further improved, and the comprehensive performance of the blade can be improved. Optionally, the solution treatment temperature is 1000°C, 1020°C or 1040°C, and the insulation time is 1h, 1.5h or 2h. Optionally, the cryogenic treatment temperature is minus 80°C or minus 70°C, and the insulation time is 1h, 1.5h or 2h. Optionally, the tempering treatment temperature is 150°C, 170°C, 190°C, and the insulation time is 2h, 4h, 6h or 8h.

[0120] In some embodiments, optionally, Figure 4 As shown, the first end of the blade is a mounting end, and the preparation method further includes: bending a side of the second end of the blade relative to the mounting end toward the other side of the blade, and the bending angle is α, and -30°≤α≤30°.

[0121] In this embodiment, generally speaking, it is difficult to take both hardness and plastic toughness into account, and thus for general high-hardness alloys, their plastic toughness is generally poor, which is not only reflected in the easy collapse of the blade during whipping, but also an important point is that the bending of the blade will be limited, because materials with poor plastic toughness will soon crack when bent, and then break due to crack expansion. However, the blade prepared by the present invention, due to the uniform distribution of nitrogen elements, not only ensures high hardness but also takes into account good plastic toughness, and supports a wider range of bending angles, which can reach 20°, 25° or 30°. Since the food is in motion during the crushing process, the blade prepared by the present invention has a larger bending angle, which can increase the scanning range of the blade, so the crushing effect on the food is better, and the crushing efficiency is improved.

[0122] In some embodiments, optionally, the method for preparing a blade further includes: polishing the blade.

[0123] In this embodiment, by polishing the blade, the smoothness of the blade surface can be further improved, and the cutting performance can be enhanced.

[0124] In some embodiments, optionally, the metal raw material is a martensitic stainless steel material.

[0125] In this embodiment, the blade prepared from the raw materials of the present invention has excellent corrosion resistance and good plasticity, and there are no visible rust spots on the blade surface after 96 hours of neutral salt spray corrosion.

[0126] As Figure 4 shown, the second aspect embodiment of the present invention provides a blade 12, aiming to improve the crushing effect of the food processor 1 and enhance the edible taste of the crushed food materials. The blade 12 provided by the present invention is prepared by the preparation method of the blade 12 provided by the first aspect of the present invention.

[0127] In some embodiments, optionally, as Figure 6 and Figure 8 shown, the blade 12 includes a cutting edge 122, and the width of the cutting edge 122 is L, where 3 mm ≤ L ≤ 7 mm.

[0128] In this embodiment, the width range of the cutting edge 122 is 3 mm ≤ L ≤ 7 mm. When the width of the cutting edge is less than 3 mm, the cutting edge is too narrow to effectively crush hard food materials such as lotus seeds. If the width of the cutting edge is too wide, the blade 12 material cannot provide effective strength support for the wide cutting edge 122, and there is a high risk of plastic deformation of the cutting edge 122 after multiple stir-fryings of dry and hard food materials (such as 300 times of dry soybeans). Generally speaking, the cutting edge width of conventional austenitic stainless steel (such as 301) is set within 5 mm, and there is a risk of plastic deformation when it exceeds 5 mm. Due to its high strength and hardness, the nitrogen-containing martensitic stainless steel in the present invention can enlarge the cutting edge width to within the range of ≤ 7 mm. Optionally, the width of the cutting edge 122 of the present invention is 5 mm ≤ L ≤ 7 mm. For example, the width of the cutting edge 122 is 5 mm, 6 mm or 7 mm.

[0129] In some embodiments, optionally, as Figure 5 shown, the minimum thickness of the cutting edge 122 is W, where 1 μm ≤ W ≤ 100 μm.

[0130] In this embodiment, the minimum thickness of the blade edge 122 is W, where 1 μm ≤ W ≤ 100 μm. Optionally, 1 μm ≤ W ≤ 10 μm. When 1 μm ≤ W ≤ 10 μm, if the hardness is lower than 50 HRC, especially lower than 45 HRC, it is extremely easy to be worn due to insufficient wear resistance or the edge to curl because of insufficient strength and hardness, resulting in a significant deterioration in the whipping effect of the blender blade 12 after a period of use, and even being inferior to the effect of normal edge sharpening (30 μm ≤ W ≤ 100 μm). In the present invention, the hardness of the blade edge 122 can be greatly improved by the uniform distribution of nitrogen element, and the maximum hardness can reach 65 HRC. Therefore, the minimum thickness of the blade edge 122 of the present invention can be set between 1 μm and 10 μm. For example, the minimum thickness of the blade edge 122 is 4 μm, 5 μm or 6 μm.

[0131] In some embodiments, optionally, when the hardness value of the blade edge 122 is greater than or equal to 50 HRC and less than or equal to 58 HRC, 4 μm < W ≤ 10 μm; when the hardness value of the blade edge 122 is greater than 58 HRC and less than or equal to 65 HRC, 1 μm ≤ W ≤ 4 μm.

[0132] In this embodiment, the hardness of the blade edge 122 can be greatly improved by the uniform distribution of nitrogen element in the present invention. The greater the hardness value, the smaller the minimum thickness W of the blade edge 122 can be set, further improving the cutting ability.

[0133] In some embodiments, optionally, the blade 12 includes nitrogen element, and the mass percentage of nitrogen element in the blade 12 is greater than or equal to 0.06% and less than or equal to 0.5%.

[0134] In this embodiment, when more than 0.06% of nitrogen element is uniformly dispersed in the material matrix, the strengthening and corrosion resistance effects can be fully exerted, ensuring that the blade 12 does not break, curl or break when whipping hard objects, and does not rust or corrode and crack when the blade 12 material is in long-term contact with a humid environment and complex food ingredients. When the nitrogen element content in the nitrogen-containing martensitic stainless steel is between 0.06% - 0.2%, although the addition of N has a positive effect, the effect of suppressing intergranular corrosion and exerting the strengthening effect of N element is limited. On the contrary, if too much nitrogen element is added, when it exceeds 0.5%, element segregation is likely to occur, which will instead affect the comprehensive performance of the material. Optionally, the mass percentage of nitrogen element in the blade 12 is greater than or equal to 0.2% and less than or equal to 0.5%, such as 0.2%, 0.3%, 0.4% or 0.5%.

[0135] In some embodiments, optionally, as Figure 5 shown, the blade includes a blade edge 122, the blade edge 122 is a straight blade edge 122, and the included angle between the upper surface and the lower surface of the blade edge 122 is a first included angle ε1, where 17° < ε1 ≤ 28°.

[0136] In this embodiment, the blade 122 of the present invention is a straight blade 122, that is, the blade 122 is formed by one-time processing, which can improve the processing efficiency. Further, the included angle between the upper surface and the lower surface of the blade 122 is the first included angle ε1, where 17° < ε1 ≤ 28°. This is because when ε ≤ 17°, the included angle is too small. When extending 0.5 mm outward from the blade tip position in the edge grinding area, the distance (i.e., thickness) between the upper and lower surfaces of the blade 122 is only 150 μm, resulting in the front end of the blade tip being easily deformed when the blade stirs dry and hard food materials, which will affect the lasting crushing effect of the blade. If ε1 ≥ 28°, it will cause the included angle to be too large and reduce the crushing effect.

[0137] In some embodiments, optionally, as Figure 7 shown, the blade 122 includes a first stage and a second stage arranged in stages. The connection point between the first stage and the second stage is the target point 1226. The first stage extends from the starting point 1222 of the blade 122 to the target point 1226, and the second stage extends from the target point 1226 to the end point 1224 of the blade 122. The included angle between the upper surface and the lower surface of the first stage is the second included angle ε2, and the included angle between the upper surface and the lower surface of the second stage is the third included angle θ, 12° ≤ ε2 ≤ 28°, 40° ≤ θ ≤ 60°.

[0138] In this embodiment, the blade 122 includes a first stage and a second stage arranged in stages. The edge grinding method of the stepped blade can further expand the range of the included angle ε. Due to the large angle of θ, it can make up for the shortcoming that the front end of the blade tip is too thin and lacks support when ε ≤ 17° in one-time edge grinding, so that the range of ε is expanded to 12° ≤ ε ≤ 28°.

[0139] In some embodiments, optionally, 12° ≤ ε2 < 17°.

[0140] In some embodiments, optionally, when 12° ≤ ε2 < 17°, 1 / 5 ≤ ε2 / θ ≤ 3 / 10; when 17° ≤ ε2 ≤ 28°, 1 / 3 ≤ ε2 / θ ≤ 2 / 3.

[0141] In this embodiment, when performing stepped edge sharpening, there is a proportional relationship between ε2 and θ. When 12° ≤ ε2 < 17°, it is necessary to increase the angle of the secondary edge sharpening θ to ensure the stiffness of the blade tip and prevent the front end of the thin edge blade 122 from being easily curled. At this time, the ratio range of ε2 / θ should be set smaller, that is, the θ value should be higher for better protection effect. When 17° ≤ ε2 ≤ 28°, the entire edge sharpening area of the blade has a certain thickness, which is beneficial to ensuring the rigidity of the front end of the blade tip. At this time, it is not necessary to set the proportional relationship of ε2 / θ too small, because when the plastic deformation of the blade tip can be ensured not to occur, the larger the θ value, the more it will affect the cutting effect of the blade tip. At this time, the angle of the secondary edge sharpening θ needs to be set smaller. Generally speaking, when the included angle ε is larger, the primary edge sharpening method is more appropriate.

[0142] In some embodiments, optionally, the thickness of the blade at the target point 1226 is greater than or equal to 100um and less than or equal to 500um.

[0143] In this embodiment, by appropriately selecting the stepped points of the stepped edge, the strength of the blade 122 can be further improved.

[0144] In some embodiments, optionally, the first end of the blade is the installation end, and the second end of the blade is bent from one side of the installation end to the other side of the blade. The upper surfaces of the first end and the second end are set at a fifth angle α, and -30° ≤ α ≤ 30°.

[0145] In this embodiment, generally speaking, since it is difficult to balance hardness and plastic toughness, for general high-hard alloys, their plastic toughness is generally poor. This is not only reflected in the easy chipping of the blade 122 during whipping, but also an important point is that the bending of the blade is restricted, because materials with poor plastic toughness will quickly show cracks during bending and then break due to crack propagation. However, for the blade prepared by the present invention, due to the uniform distribution of nitrogen elements, while ensuring high hardness, it also has good plastic toughness, supports a larger range of bending angles, and can meet the condition of bending 30°. The larger the ultimate bending angle of the blade material, the more conducive to the flexible design of the blade and the ability to meet more whipping usage scenarios. Optionally, 10° ≤ α ≤ 30°, such as 20°, 25° or 30°.

[0146] In some embodiments, optionally, one end of the blade is the installation end, and the end of the other end of the blade is provided with a blade tip, and a serrated structure is provided on the blade tip.

[0147] In this embodiment, a micro-serrated structure is provided at the blade tip. This structure can play a sawing effect when whipping food materials, which helps to improve the crushing efficiency, reduce the crushing particle size, and also enhance the friction with the food materials, and can suppress food splashing while improving the whipping effect.

[0148] In some embodiments, optionally, the blade includes a cutting edge 122, and a texture is provided on the lower surface of the blade and extends to the cutting edge 122.

[0149] In this embodiment, by providing a texture on the lower surface of the blade and extending the texture to the cutting edge 122, a micro-serrated structure can be formed at the tip of the blade, which can exert a sawing effect when whipping food materials, helping to improve the crushing efficiency and reduce the crushing particle size. At the same time, the texture design of the strip-shaped ridges 124 can also enhance the friction with the food materials, suppressing food splashing while improving the whipping effect.

[0150] In some embodiments, optionally, as Figure 7 shown, the texture is arranged in a first direction, and the first direction is set at a fourth angle with respect to the edge-opening direction of the cutting edge 122, where the fourth angle is greater than 80° and less than 100°.

[0151] In this embodiment, the arrangement direction of the texture is close to perpendicular to the edge-opening direction of the cutting edge 122, which can further ensure the overall strength of the blade.

[0152] In some embodiments, optionally, the texture includes a plurality of ridges 124 arranged parallel and spaced along the edge-opening direction, and a recessed area is formed between adjacent two ridges 124. The depth of the recessed area is greater than or equal to 0.1 mm and less than or equal to 0.5 mm.

[0153] In this embodiment, the recessed depth determines the concave-convex effect of the micro-serrations after edge-opening. When the recessed depth is less than 0.1 mm, the concave-convex structure of the micro-serrations after edge-opening is not obvious and cannot effectively exert the sawing effect. When the recessed depth is greater than 0.5 mm, on the one hand, the improvement of the sawing efficiency is limited, and on the other hand, due to the too-deep groove on the lower surface of the blade, the too-deep groove will affect the overall rigidity of the blade and is not conducive to the long-term reliability of the blade operation.

[0154] In some embodiments, optionally, the spacing range between adjacent two ridges 124 is greater than or equal to 0.2 mm and less than or equal to 1 mm.

[0155] In this embodiment, the spacing range of the parallel ridges 124 is 0.2 mm - 1 mm. If the spacing is too narrow, it is not much different from a flat-edge knife. If the spacing is too wide, the serration density after edge-opening is insufficient to form the sawing effect of the micro-serrations.

[0156] In some embodiments, optionally, the blade includes a nitrogen-containing martensitic stainless steel blade.

[0157] In this embodiment, the nitrogen-containing martensitic stainless steel blade has excellent corrosion resistance and good plasticity, and there are no visible rust spots on the blade surface after 96 hours of neutral salt spray corrosion.

[0158] In some embodiments, optionally, the total mass percentage of nitrogen element and carbon element in the blade 12 is greater than or equal to 0.3% and less than or equal to 0.8%.

[0159] In this embodiment, by controlling the sum of the mass percentages of nitrogen element and carbon element to be greater than or equal to 0.3% and less than or equal to 0.8%, the content of nitrogen element and carbon element can be increased, and the strength of the blade 12 can be improved. However, the total mass of nitrogen element and carbon element should not be too large, otherwise it will reduce the comprehensive performance of the blade 12.

[0160] This embodiment provides a blade, which relates to a blade material for a wall breaker, aiming to improve the crushing effect of the wall breaker and enhance the edible taste of the crushed food materials.

[0161] The blade material belongs to nitrogen-containing martensitic stainless steel, and the mass percentage of nitrogen content in the steel is 0.06%-0.5%.

[0162] Among them, the nitrogen element in the stainless steel has a uniform and dispersed distribution characteristic. After the rod-shaped blank is vertically cut at a position at least 5 cm above the end, no less than 10 points are sampled in any area from the surface to the core (such as Figure 3 ), and the nitrogen content of each point sample is measured using a nitrogen and oxygen analyzer, and the deviation of the test results between points does not exceed 5%.

[0163] The hardness value of the nitrogen-containing stainless steel is HRC50-65, and it has excellent corrosion resistance, and there are no visible rust spots on the surface after 96 hours of neutral salt spray corrosion.

[0164] Furthermore, after the nitrogen-containing stainless steel is processed into a wall breaker blade, the folding angle can achieve a maximum bending degree of 30°, that is, the angle between the folding cutter and the installation plane is defined as α, -30° ≤ α ≤ 30°.

[0165] The chemical composition mass percentage (wt.%) of the nitrogen-containing stainless steel is as follows: N: 0.06%-0.5%, Cr: 12%-16%, Ni: 0.1%-0.8%, Mo: 0.5%-1.5%, Si ≤ 1.0%, Mn ≤ 1.0%, C: 0.15%-0.35%, S ≤ 0.03%, P ≤ 0.04%, Fe: balance.

[0166] The total content of N element and C element in the nitrogen-containing stainless steel has a minimum requirement, N+C (wt.%) ≥ 0.3%.

[0167] Specifically, the production process of the nitrogen-containing stainless steel includes the following steps:

[0168] The first step: Put each alloy into the induction furnace for melting according to its mass percentage. After induction furnace melting, secondary refining can be carried out by ladle furnace refining (LF) + vacuum degassing (VD) according to needs to obtain an alloy ingot.

[0169] Step 2: Using a pressurized electroslag remelting (PESR) reactor, add high-nitrogen alloy particles such as silicon nitride, chromium nitride, manganese nitride, etc. to the remelting slag, and simultaneously introduce nitrogen gas. The nitrogen partial pressure in the melting chamber is ≥ 10 Bar. Pressurized electroslag remelting can not only increase the solubility of nitrogen in the melt but also contribute to the homogenization of nitrogen, forming a uniform and dispersed distribution effect within the alloy.

[0170] Step 3: Hot forge the embryo at a forging temperature of 900°C - 1100°C, and then hot roll it into a 10-mm-thick plate.

[0171] Step 4: Conduct multi-pass cold rolling on the hot-rolled plate, and finally roll it into a 1.5-mm-thick thin plate.

[0172] Step 5: Heat-treat the cold-rolled thin plate. The heat treatment process is solution treatment + cryogenic treatment + tempering. Among them, the solution treatment temperature is 1000°C - 1050°C, and the holding time is 1 h - 2 h; the cryogenic treatment temperature is -73°C, and the holding time is 1 h - 2 h; the tempering temperature is 150°C - 200°C, and the holding time is 2 - 8 h.

[0173] The thin plate is semi-finished processed to the specified size and accuracy according to the drawing requirements by means of stamping, wire cutting, etc., and then the blade is edge-ground and bent at an angle, and then electrolytically polished to obtain the wall-breaking machine blade.

[0174] Specifically, when the blade is edge-ground, the distance between the upper and lower surfaces at the thinnest part of the blade edge is defined as W, and 1 μm ≤ W ≤ 100 μm.

[0175] Preferably, the distance W between the upper and lower surfaces at the thinnest part of the blade edge is 1 μm ≤ W ≤ 10 μm. The thin-edge blade can achieve a better cutting effect. The high strength and high hardness characteristics of nitrogen-containing stainless steel can ensure that the thin-edge blade is not prone to edge rolling when crushing hard ingredients such as dry soybeans and ice cubes, and can provide a lasting and stable crushing effect.

[0176] The preferred nitrogen content in the nitrogen-containing martensitic stainless steel with a uniform and dispersed distribution of nitrogen elements is 0.2% - 0.5%. When more than 0.2% of nitrogen elements are uniformly dispersed in the material matrix, the strengthening and corrosion resistance effects can be fully exerted, ensuring that the blade does not crack, edge roll, or break when beating hard objects, and does not rust or corrode and crack when the blade material is in long-term contact with a humid environment and complex ingredients. When the nitrogen element content in the nitrogen-containing martensitic stainless steel is between 0.06% - 0.2%, although the addition of N has a positive effect, the effect of suppressing intergranular corrosion and exerting the strengthening effect of the N element by adding the N element is limited. On the contrary, if too much nitrogen element is added, exceeding 0.5%, element segregation is likely to occur, which will instead affect the comprehensive performance of the material.

[0177] In summary, the nitrogen-containing stainless steel blade material can ensure plastic toughness while achieving ultra-high strength on the one hand, and improve corrosion resistance on the other hand. The blade surface does not require coating protection, and it has a wide range of applications.

[0178] As Figure 4 shown, in the third aspect of the embodiments of the present invention, a food processor 1 is provided, including the blade 12 provided in any one of the embodiments of the second aspect of the present invention. Optionally, the food processor 1 of the present invention is a wall breaker.

[0179] The mechanism for improving the strength, hardness, plastic toughness and corrosion resistance of the blade of the present invention is as follows:

[0180] Traditional blade materials are all selected from conventional materials, represented by austenitic stainless steel or martensitic stainless steel. Among them, although austenitic stainless steel has good plastic toughness, since it cannot be strengthened by heat treatment and can only improve strength by cold working hardening, the improvement of its strength is accompanied by an obvious decrease in plastic toughness, and the effect of improving material strength is limited. Conventional martensitic stainless steel can improve its comprehensive mechanical properties through heat treatment strengthening, but its corrosion resistance is insufficient and cannot meet the requirements of the wall breaker blade material for corrosion-resistant application scenarios. In order to improve the corrosion resistance of martensitic stainless steel, a coating needs to be applied on the surface of the base material. However, there is a risk of coating peeling off during long-term beating of hard objects, and the probability of pitting corrosion is even higher after the coating peels off.

[0181] The blade material involved in the present invention is a nitrogen-containing martensitic stainless steel. Under normal pressure conditions (1 bar), the solubility of nitrogen in Fe-Cr alloy system steel is very low, and the uniform distribution is not good, and pores are easily generated during the solidification process. Under high nitrogen pressure conditions, the solubility of nitrogen will increase with the increase of nitrogen partial pressure. Therefore, pressurized electroslag remelting (PESR) is the most effective production method for obtaining homogenized high-nitrogen steel.

[0182] The nitrogen-containing stainless steel not only has uniform and fine grains, but also has high strength, good plasticity and good corrosion resistance. As an interstitial solid solution atom, the nitrogen atom has a solid solution strengthening effect. In addition, by refining the grains, the grain boundary area increases, and the dislocation movement to the grain boundary will be hindered, resulting in fine grain strengthening. Moreover, the addition of nitrogen can also play a precipitation strengthening role.

[0183] Adding nitrogen element to martensitic stainless steel can obtain stainless steel with excellent corrosion resistance. The nitrogen element helps the short-range ordered arrangement of atoms, reduces the diffusion coefficient of Cr in the steel, reduces the loss of Cr in the matrix, and improves the corrosion resistance. The excellent corrosion resistance enables the blade to not require coating protection, and there is no need to worry about the risk of external substances penetrating into the matrix surface to cause corrosion or rust after the coating is damaged during beating and crushing, and the application range is wider.

[0184] The addition of nitrogen element helps to improve the comprehensive performance of nitrogen-containing stainless steel. High hardness can ensure the crushing and cutting effect on food ingredients. When the edge width is less than 10um, if the hardness is lower than 50HRC, especially lower than 45HRC, it is extremely easy to be worn due to insufficient wear resistance and the edge will curl due to insufficient strength and hardness. For the conventional technology that uses increasing carbon content as the main means to increase hardness, due to the presence of a large number of carbide phases in the high-hard material, although it helps to increase hardness, the material will become brittle. When used as the material for the blender blade, it cannot be bent at a large angle, and it is very easy to have fatigue failure and even sudden fracture during use due to insufficient toughness. Nitrogen-containing stainless steel makes the material have excellent strength and toughness by controlling the carbide phase and promoting the nitride phase, ensuring the reliability when whipping food ingredients, and also supporting a larger range of bending angles. The bending angle can reach ±30°. The larger the ultimate bending angle of the material, the more conducive it is to the flexible design of the blade and the increase of usage scenarios.

[0185] Generally speaking, this material can meet the application scenario requirements of the blender blade in several dimensions such as strength, hardness, plasticity, toughness, and corrosion resistance. There is no coating on the surface of the matrix material and no special treatment is required, and the production process is simple; there are no precious metals in the material composition, and the cost is controllable; the material does not contain toxic and harmful metals, meeting food safety requirements.

[0186] The beneficial effects of the present invention are as follows:

[0187] 1. The uniform distribution of nitrogen element in the nitrogen-containing stainless steel blade material not only makes the structure uniform and fine, but also has high strength, good plasticity, and good corrosion resistance. On the one hand, it can obtain ultra-high strength while ensuring plastic toughness, and on the other hand, it can improve corrosion resistance, and can meet the application scenario requirements of the blender blade in several dimensions such as strength, hardness, plasticity, toughness, and corrosion resistance;

[0188] 2. The surface of the blade does not require coating protection to ensure food safety;

[0189] 3. By setting the edge thickness and angle of the blade, the improvement effect on the pulp taste is enhanced, the particle size is reduced, and the slurry is more delicate and smooth.

[0190] In an embodiment according to the present invention, the terms "first", "second", "third" are only used for descriptive purposes and should not be construed as indicating or implying relative importance; the term "plural" means two or more, unless otherwise clearly defined. Terms such as "installed", "connected", "joined", "fixed" and the like should be understood in a broad sense. For example, "connected" can be a fixed connection, a detachable connection, or an integral connection; "joined" can be a direct connection or an indirect connection through an intermediate medium. For those of ordinary skill in the art, the specific meanings of the above terms in the embodiments according to the present invention can be understood according to specific circumstances.

[0191] In addition, although the operations are depicted in a particular order, this should be understood to require that the operations be performed in the particular order shown or in a sequential order, or that all of the illustrated operations be performed to achieve the desired result. In certain circumstances, multitasking and parallel processing may be advantageous. Similarly, although a number of specific implementation details are included in the above discussion, these should not be construed as limiting the scope of the present invention. Certain features described in the context of separate embodiments may also be implemented in combination in a single implementation. Conversely, the various features described in the context of a single implementation may also be implemented separately or in any suitable sub-combination in multiple implementations.

[0192] Although the subject matter has been described in language specific to structural features and / or methodological acts, it should be understood that the subject matter defined in the appended claims is not necessarily limited to the specific features or acts described above. On the contrary, the specific features and acts described above are merely example forms for implementing the claims. The above are only the preferred embodiments according to the embodiments of the present invention and are not used to limit the embodiments according to the present invention. For those skilled in the art, various changes and modifications can be made according to the embodiments of the present invention. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the embodiments according to the present invention shall be included within the protection scope of the embodiments according to the present invention.

Claims

1. A method for preparing a blade, characterized in that, The blade includes nitrogen element, and the mass percentage of the nitrogen element in the blade is greater than or equal to 0.06% and less than or equal to 0.5%. The content of the nitrogen element at any position in the blade is greater than or equal to m(1 - 5%) and less than or equal to m(1 + 5%), where m is the percentage of the mass of the nitrogen element in the total mass of the blade. The preparation method of the blade includes: Smelting the metal raw material in a nitrogen-containing environment to obtain a metal solution; Preparing the metal solution into a blank; Preparing the blade from the blank.

2. The preparation method of the blade according to claim 1, characterized in that, The step of smelting the metal raw material in a nitrogen-containing environment to obtain a metal solution includes: Adding a nitride to the metal raw material for smelting to obtain the metal solution.

3. The preparation method of the blade according to claim 2, wherein, The nitride includes at least one of the following or a combination thereof: silicon nitride, chromium nitride, manganese nitride.

4. The preparation method of the blade according to claim 1, characterized in that, The step of smelting the metal raw material in a nitrogen-containing environment to obtain a metal solution includes: Smelting the metal raw material in a nitrogen environment to obtain the metal solution, and in the nitrogen environment, the nitrogen pressure is greater than the target pressure.

5. The method for preparing a blade according to any one of claims 1 to 4, characterized in that, The step of preparing the blade from the blank includes: Hot forging the blank, and then hot rolling to form a first plate with a first thickness; Performing multi-pass cold rolling on the first plate to obtain a second plate with a second thickness, and the second thickness is less than the first thickness; Performing heat treatment on the second plate; Processing the heat-treated second plate into the blade.

6. The preparation method of the blade according to claim 5, wherein When hot rolling the blank, the hot rolling temperature is greater than or equal to 900°C and less than or equal to 1100°C; and / or When performing multi-pass cold rolling on the first plate, the cold rolling temperature is greater than or equal to 0°C and less than or equal to 200°C.

7. The preparation method of the blade according to claim 5, characterized in that, The step of performing heat treatment on the second plate includes: performing solution treatment, cryogenic treatment and tempering treatment on the second plate, wherein During the solution treatment, the temperature is greater than or equal to 1000°C and less than or equal to 1050°C, and the holding time is greater than or equal to 1h and less than or equal to 2h; During the cryogenic treatment, the temperature is greater than or equal to -80°C and less than or equal to -70°C, and the holding time is greater than or equal to 1h and less than or equal to 2h; The tempering treatment temperature is greater than or equal to 150°C and less than or equal to 200°C, and the holding time is greater than or equal to 2h and less than or equal to 8h.

8. The method for preparing a blade according to any one of claims 1 to 4, characterized in that, The first end of the blade is the installation end, and the preparation method further includes: Bending the second end of the blade from one side relative to the installation end to the other side of the blade, and the bending angle is α, and -30° ≤ α ≤ 30°.

9. The preparation method of the blade according to any one of claims 1 to 4, characterized in that, The metal raw material is a martensitic stainless steel material.

10. A blade, characterized in that, The blade is prepared by the preparation method of the blade according to any one of claims 1 to 9.

11. The blade according to claim 10, characterized in that, The blade includes a cutting edge, The width of the cutting edge is L, and 3mm ≤ L ≤ 7mm; or The minimum thickness of the cutting edge is W, where 1um ≤ W ≤ 100um.

12. The blade according to claim 10, characterized in that, The blade includes a cutting edge, The cutting edge is a straight cutting edge, and the included angle between the upper surface and the lower surface of the cutting edge is a first included angle ε1, where 17° < ε1 ≤ 28°.

13. The blade according to claim 10, wherein The blade includes a cutting edge. The cutting edge includes a first section and a second section arranged in stages. The connection point between the first section and the second section is the target point. From the starting point of the cutting edge to the target point is the first section, and from the target point to the ending point of the cutting edge is the second section. The included angle between the upper surface and the lower surface of the first section is a second included angle ε2, and the included angle between the upper surface and the lower surface of the second section is a third included angle θ, where 12° ≤ ε2 ≤ 28° and 40° ≤ θ ≤ 60°.

14. The blade according to claim 10, wherein, The blade further includes carbon element, and the total mass percentage of nitrogen element and carbon element in the blade is greater than or equal to 0.3% and less than or equal to 0.8%.

15. A food processor, characterized in that, It includes the blade according to any one of claims 10 to 14.

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