60niti alloy slab and short process preparation method thereof, superhard cutter and preparation method thereof

Abstract

This invention relates to a 60NiTi alloy slab and its short-process preparation method, as well as a superhard cutting tool and its preparation method, to solve at least one of the problems of existing 60NiTi alloy slabs, such as difficulty in stable forging, low yield, and poor comprehensive mechanical properties of subsequently processed products. The short-process preparation method for 60NiTi alloy slabs includes the following steps: preparing a billet; coating the surface of the billet with a high-temperature anti-oxidation lubricating coating; encapsulating the coated billet in a first sleeve to obtain a first-sleeved billet; then coating the surface of the first-sleeved billet with a high-temperature anti-oxidation lubricating coating, and then encapsulating it in a second sleeve to obtain a second-sleeved billet; performing a single-fire forging of the second-sleeved billet using a two-step heating process; and removing the first and second sleeves to obtain a 60NiTi alloy slab. This method enables efficient and stable forging of 60NiTi alloy slabs, obtaining high-quality 60NiTi alloy slabs with uniform microstructure and consistent properties, and improving the comprehensive mechanical properties of subsequently processed products.

Description

Technical Field

[0001] This invention relates to the field of alloy technology, and in particular to a 60NiTi alloy slab and its short-process preparation method, and a superhard cutting tool and its preparation method. Background Technology

[0002] As a high-performance superhard alloy, 60NiTi alloy has shown great application potential in aerospace, marine, and biomedical fields due to its excellent strength, stability, and good corrosion resistance, and has attracted widespread attention from the materials field at home and abroad.

[0003] The phase composition of 60NiTi alloy is extremely complex, mainly consisting of intermetallic compounds such as Ni3Ti, Ni4Ti3, and NiTi. Among them, Ni3Ti and Ni4Ti3 exhibit significant intrinsic brittleness and are highly susceptible to cracking. In existing technologies, surface and center cracking easily occurs during hot working of 60NiTi alloy slabs, resulting in problems such as unstable forging, low yield, and poor overall mechanical properties of subsequent processed products (such as cutting tools).

[0004] Therefore, there is an urgent need to develop a new method for preparing 60NiTi alloy slabs to achieve efficient and stable forging of 60NiTi alloy slabs, thereby improving the yield and the comprehensive mechanical properties of the processed products. Summary of the Invention

[0005] Based on the above analysis, the present invention aims to provide a 60NiTi alloy slab and its short-process preparation method, and a superhard cutting tool and its preparation method, to solve at least one of the problems of existing 60NiTi alloy slabs, such as difficulty in stable forging, low yield, and poor comprehensive mechanical properties of subsequent processed products.

[0006] On one hand, the present invention provides a short-process preparation method for 60NiTi alloy slabs, comprising the following steps: S1. Prepare the blank; S2. A high-temperature anti-oxidation and lubricating coating is applied to the surface of the blank to obtain a coated blank; S3. The coated blank is encapsulated in a first sleeve to obtain a first sleeve blank. The surface of the first sleeve blank is then coated with the high-temperature anti-oxidation lubricating coating and encapsulated in a second sleeve to obtain a second sleeve blank. S4. The second cladding blank is forged in one heat using a two-step heating process. S5. Remove the first and second claddings to obtain the 60NiTi alloy slab.

[0007] Furthermore, the ratio of the thickness of the second sheath to the thickness of the first sheath is 2 to 4.

[0008] Furthermore, the thickness of the second sheath satisfies: (the thickness of the blank × 15% - the thickness of the first sheath) ≤ the thickness of the second sheath ≤ (the thickness of the blank × 25% - the thickness of the first sheath).

[0009] Furthermore, the thickness of the first sheath is 2~5mm.

[0010] Furthermore, the thickness of the second sheath is 4~20mm.

[0011] Furthermore, the process of forging the second cladding billet in S4 using a two-step heating method in one pass includes: S41. Place the second-encased billet in the furnace at 750~850℃ and hold for 240~300 minutes. S42. Then, within 30-60 minutes, raise the temperature to 850-1000℃; hold at that temperature for 300-480 minutes. S43. Perform controlled-speed forging, and after forging to the finished product, place it in a furnace at 500~600℃ for furnace cooling.

[0012] Furthermore, the deformation speed of the controlled-speed forging in S43 is 15~20mm / s.

[0013] On the other hand, the present invention provides a 60NiTi alloy slab, which is prepared by the above-mentioned short-process preparation method for 60NiTi alloy slab.

[0014] On the other hand, the present invention provides a superhard cutting tool, which is prepared by using the above-mentioned short-process preparation method of 60NiTi alloy blank or by machining the above-mentioned 60NiTi alloy blank.

[0015] On the other hand, the present invention provides a method for preparing a superhard cutting tool, comprising the following steps: cutting and grinding the 60NiTi alloy slab to obtain a cutting tool model, placing the cutting tool model in a furnace at 1000~1100℃ and holding it for 60~180 minutes, water cooling, and grinding to obtain a superhard cutting tool.

[0016] Compared with the prior art, the present invention can achieve at least one of the following beneficial effects: 1. The preparation method of 60NiTi alloy slab in this invention, through double-layer cladding (first cladding and second cladding) and one-time forging, can achieve efficient and stable forging of 60NiTi alloy slab in a short process, effectively improving its yield.

[0017] 2. In the preparation method of 60NiTi alloy slab in this invention, by controlling the process parameters such as temperature, holding time, and deformation speed in different steps, the 60NiTi alloy slab is formed stably, and a high-quality 60NiTi alloy slab with uniform structure and consistent performance is obtained, providing a reliable base material for subsequent processing and end applications, and improving the comprehensive mechanical properties of the processed products.

[0018] In this invention, the above-described technical solutions can be combined with each other to achieve more preferred combinations. Other features and advantages of this invention will be set forth in the following description, and some advantages may become apparent from the description or be learned by practicing the invention. The objects and other advantages of this invention can be realized and obtained from what is particularly pointed out in the description and drawings. Attached Figure Description

[0019] The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. Throughout the drawings, the same reference numerals denote the same parts.

[0020] Figure 1 This is a metallographic image of the edge position of the 60NiTi alloy slab along the width direction in Embodiment 1 of the present invention; Figure 2 This is a metallographic image of the 60NiTi alloy slab in Example 1 of the present invention, taken along 1 / 4 of the slab width in the width direction; Figure 3 This is a metallographic image of the 60NiTi alloy slab in Example 1 of the present invention, taken along half the width of the slab. Detailed Implementation

[0021] The preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings, which constitute a part of the present invention and are used together with the embodiments of the present invention to illustrate the principles of the present invention, but are not intended to limit the scope of the present invention.

[0022] The preparation of 60NiTi alloy mainly relies on powder metallurgy, which directly prepares shaped parts through powder pressing and sintering, thus avoiding the forming difficulties caused by hot working processes such as forging to a certain extent. However, it also has the following insurmountable drawbacks: First, the process is cumbersome, requiring multiple steps such as powder preparation, sieving, pressing, sintering, and post-processing, resulting in a long production cycle; second, the production cost is high, as the powder preparation and subsequent sintering processes have stringent equipment requirements and low raw material utilization; third, controlling the oxygen content is difficult, as the powder is highly susceptible to oxidation during preparation and processing, leading to the formation of oxide inclusions inside the alloy, which seriously affects the mechanical properties of the material; fourth, bonding defects are prone to occur inside the shaped parts, as the bonding between powder particles is difficult to achieve complete density during sintering, easily forming defects such as pores and inclusions, reducing the reliability of the components, making it difficult to meet the stringent requirements for material performance in high-end fields, and limiting its large-scale application.

[0023] Therefore, to solve the above problems, traditional forging technology can be used to prepare 60NiTi alloy. However, traditional forging technology requires forging the 60NiTi alloy in the medium-temperature forming range (800~1100℃) to refine the microstructure. But as forging progresses, the 60NiTi alloy is prone to precipitation of the brittle Ni4Ti3 phase due to rapid cooling, which leads to cracks easily appearing on the surface and in the core of the 60NiTi alloy, making it impossible to form. In addition, improper control of strain rate and temperature range during forging will promote stress concentration inside the alloy, causing frequent cracking on the surface and in the central area of ​​the forging, making it impossible to achieve stable forming.

[0024] Based on this, a specific embodiment of the present invention discloses a short-process preparation method for 60NiTi alloy slabs, comprising the following steps: S1. Prepare the blank; S2. Apply a high-temperature anti-oxidation and lubricating coating to the surface of the billet to obtain the coated billet; S3. The coated blank is encapsulated in the first sleeve to obtain the first sleeve blank. Then, a high-temperature anti-oxidation lubricating coating is applied to the surface of the first sleeve blank, and then it is encapsulated in the second sleeve to obtain the second sleeve blank. S4. The second sheath blank is forged in one heat using a two-step heating process. S5. Remove the first and second cladding to obtain a 60NiTi alloy slab.

[0025] Compared with existing technologies, the short-process preparation method for 60NiTi alloy slabs provided in this embodiment utilizes a double-layer sheathing (first sheath and second sheath) technology. The first sheath is beneficial for heat preservation of the slab during forging and suppresses the precipitation of brittle phases. The second sheath and the first sheath form an air insulation layer, which further enhances the heat preservation effect and can provide triaxial compressive stress to the slab, suppressing cracking of the slab and the first sheath. Furthermore, the forging process is precisely formulated based on the transformation law between brittle phases and matrix phases, and a two-step heating process is used for single-fire forging. This suppresses the cracking problem caused by the precipitation of Ni4Ti3 brittle phases during medium-temperature forming, bridging the micro-defects of 60NiTi alloy and refining the grains, thereby improving the medium-temperature plasticity of 60NiTi alloy and enabling efficient and stable forging of 60NiTi alloy slabs. In addition, applying a high-temperature anti-oxidation lubricating coating to the surface of the billet and the first cladding billet facilitates the removal of the first and second claddings, resulting in a complete 60NiTi alloy slab, and avoiding severe adhesion between the billet, the first cladding, and the second cladding, which prevents them from being separated.

[0026] In some embodiments, the composition of the green body, by mass percentage, includes: Ni: 59.4%~61.0%, Ti: 39.0%~40.6%, Fe: ≤0.15%, O: ≤0.1%, N: ≤0.01%, C: ≤0.08%, H: ≤0.015%.

[0027] Specifically, the mass percentage of Ni can be a range of 59.4%, 59.5%, 59.8%, 60.0%, 60.2%, 60.4%, 60.5%, 60.8%, 61.0%, or any combination thereof.

[0028] Specifically, the mass percentage of Ti can be a range of 39.0%, 39.2%, 39.5%, 39.8%, 40.0%, 40.2%, 40.5%, 40.6%, or any combination thereof.

[0029] In some embodiments, the billet includes a round billet and / or a square billet.

[0030] In some embodiments, the thickness of the blank is 45 to 55 mm, for example, 45 mm, 46 mm, 47 mm, 48 mm, 49 mm, 50 mm, 51 mm, 52 mm, 53 mm, 54 mm, 55 mm or any combination thereof.

[0031] Specifically, the thickness of the high-temperature anti-oxidation lubricating coating in S2 is 1~2mm, for example, 1mm, 1.2mm, 1.5mm, 1.8mm, 2mm or any combination thereof, which is beneficial to improving the uniformity of the 60NiTi alloy slab and the removal of the first and second cladding.

[0032] Specifically, the thickness of the high-temperature anti-oxidation lubricating coating in S3 is 1~2mm, such as 1mm, 1.2mm, 1.5mm, 1.8mm, 2mm, which is beneficial to improving the uniformity of the 60NiTi alloy slab and the removal of the first and second cladding.

[0033] Specifically, the high-temperature anti-oxidation lubricating coatings in S2 and S3 can include glassy coatings. Specifically, the glassy coating can be applied by applying anti-oxidation glass powder. Glassy coatings are low in cost and easy to peel off, which helps to reduce the preparation cost of 60NiTi alloy slabs and the removal during subsequent processing.

[0034] In some embodiments, the ratio of the thickness of the second sheath to the thickness of the first sheath is 2 to 4, for example, 2, 2.5, 3, 3.5, 4 or any combination thereof. When the ratio of the thickness of the second sheath to the thickness of the first sheath is within the above range, it is beneficial for the first sheath to play a role in heat preservation and oxidation resistance, and it is also beneficial for the second sheath to provide forging triaxial compressive stress, further suppressing cracking of the billet and the first sheath, so as to achieve stable forging of the 60NiTi alloy slab.

[0035] In some embodiments, the thickness of the first sheath is 2 to 5 mm, such as 2 mm, 2.5 mm, 3 mm, 3.5 mm, 4 mm, 4.5 mm, 5 mm or any combination thereof, which is more conducive to forming an air / coating insulation layer, reducing heat dissipation of the billet, and helping to suppress oxidation of the billet and improve the mechanical properties of the 60NiTi alloy slab.

[0036] In some embodiments, the thickness of the second sheath is 4 to 20 mm, for example, 4 mm, 5 mm, 6 mm, 7 mm, 8 mm, 9 mm, 10 mm, 11 mm, 12 mm, 13 mm, 14 mm, 15 mm, 16 mm, 17 mm, 18 mm, 19 mm, 20 mm or any combination thereof, which is more conducive to providing forging triaxial compressive stress to the first sheath blank, suppressing cracking of the blank and the first sheath, and enabling the 60NiTi alloy slab to be forged stably.

[0037] In some embodiments, the thickness of the second sheath satisfies: (blank thickness × 15% - first sheath thickness) ≤ second sheath thickness ≤ (blank thickness × 25% - first sheath thickness), which is beneficial to further improve the performance consistency of 60NiTi alloy slabs.

[0038] Furthermore, in S3, the coated blank can be encapsulated in the first sleeve by welding (such as fusion welding) to obtain the first sleeve blank. Then, a high-temperature anti-oxidation lubricating coating is applied to the surface of the first sleeve blank, and then it is encapsulated in the second sleeve by welding to obtain the second sleeve blank.

[0039] Specifically, both the first and second clasps can be made of steel. Steel clasps are low in cost and have high elongation, making them less prone to cracking during subsequent forging.

[0040] In some embodiments, the process of forging the second cladding billet in one pass using two-step heating in S4 includes: S41. Place the second-encased billet in the furnace at 750~850℃ and hold for 240~300 minutes. S42. Then, within 30-60 minutes, raise the temperature to 850-1000℃; hold at that temperature for 300-480 minutes. S43. Perform controlled-speed forging to obtain the forged finished product, and then place the forged finished product in a furnace at 500~600℃ for furnace cooling.

[0041] In the above system, the second cladding billet is forged through a two-step heating process. First, it is held at 750~850℃ to preheat the billet, which promotes the transformation of Ni4Ti3 into cubic NiTi, making the billet easier to deform and inhibiting grain growth. This helps refine the grains during subsequent forging, making the billet less prone to cracking and ensuring stable forming of the 60NiTi alloy slab. The subsequent holding at 850~1000℃ promotes the remelting of Ni3Ti, removes heterogeneous phases, inhibits grain coarsening, and improves alloy toughness, making the billet less prone to cracking during processing and further facilitating the stable forging of the 60NiTi alloy slab.

[0042] Specifically, in S41, the second packaged billet can be placed in the furnace and held at 750~850℃ (e.g., 750℃, 760℃, 770℃, 780℃, 790℃, 800℃, 810℃, 820℃, 830℃, 840℃, 850℃ or any combination thereof) for 240~300min (e.g., 240min, 250min, 260min, 270min, 280min, 290min, 300min or any combination thereof).

[0043] Specifically, in S42, the temperature can be raised to 850-1000℃ (e.g., 850℃, 900℃, 950℃, 975℃, 1000℃ or any two of these ranges) within a range of 30-60 minutes (e.g., 30 minutes, 35 minutes, 40 minutes, 45 minutes, 50 minutes, 55 minutes, 60 minutes or any two of these ranges) and held for 300-480 minutes (e.g., 300 minutes, 330 minutes, 350 minutes, 380 minutes, 400 minutes, 430 minutes, 450 minutes, 480 minutes or any two of these ranges).

[0044] Specifically, in S43, after forging to the finished product, it can be placed in a furnace at 500~600℃ (e.g., 500℃, 520℃, 550℃, 580℃, 600℃ or any combination thereof) for furnace cooling to avoid rapid cooling of the 60NiTi alloy slab, reduce its residual stress, and make the 60NiTi alloy slab less prone to cracking.

[0045] Specifically, the thickness of the finished product after forging in S43 is 22~42mm, for example, 22mm, 25mm, 30mm, 35mm, 40mm, 42mm or any combination thereof.

[0046] In some embodiments, the deformation speed of the controlled-speed forging in S43 is 15~20 mm / s, such as 15 mm / s, 16 mm / s, 17 mm / s, 18 mm / s, 19 mm / s, 20 mm / s or any combination thereof. This is more conducive to the dynamic recrystallization of the 60NiTi alloy slab, which is beneficial to the stable forming of the 60NiTi alloy slab and improves the uniformity of the microstructure of the 60NiTi alloy slab. It avoids the 60NiTi alloy slab from having insufficient dynamic recrystallization due to excessive deformation speed, which would result in large differences in the microstructure of the 60NiTi alloy slab and poor consistency of mechanical properties.

[0047] In practice, during the controlled-speed forging process of S43, the hammer anvil can be preheated to 250~400℃ in advance, and the anvil can be flattened to avoid the second-encased billet from becoming extremely cold on the surface and losing internal temperature during forging, thus preventing the reappearance of hard phases.

[0048] In practice, the process of removing the first and second sheaths in S5 can be carried out using conventional methods in the art, such as using a grinding wheel to remove the first and second sheaths.

[0049] This invention also provides a 60NiTi alloy slab, which is prepared using the above-described short-process preparation method for the 60NiTi alloy slab.

[0050] In some embodiments, the thickness of the 60NiTi alloy slab is 20~40mm, for example, a range of 20mm, 23mm, 25mm, 28mm, 30mm, 33mm, 35mm, 38mm, 40mm or any combination thereof, which facilitates the manufacture of subsequent processed products using the 60NiTi alloy slab as raw material.

[0051] In some embodiments, the hardness of the 60NiTi alloy slab is 20 to 30 HRC, for example, a range of 20 HRC, 21 HRC, 22 HRC, 23 HRC, 24 HRC, 25 HRC, 26 HRC, 27 HRC, 28 HRC, 29 HRC, 30 HRC, or any combination thereof.

[0052] In this invention, the hardness of the 60NiTi alloy slab refers to the average hardness of the 60NiTi alloy slab, that is, at least five locations of the 60NiTi alloy slab are randomly selected and subjected to single-point hardness testing in accordance with GB / T230.1-2018, and the average value is taken as the hardness of the 60NiTi alloy slab.

[0053] Furthermore, the 60NiTi alloy slab in the embodiments of the present invention has good uniformity, and the hardness deviation of the 60NiTi alloy slab (i.e., the ratio of the maximum difference between the single-point hardness and the average hardness of the 60NiTi alloy slab to the average hardness) is 3% to 9%, for example, 3%, 4%, 5%, 6%, 7%, 8%, 9% or any combination thereof.

[0054] This invention also provides a superhard cutting tool, which is prepared from a 60NiTi alloy blank obtained by the above-described short-process preparation method for 60NiTi alloy blanks or processed from the above-described 60NiTi alloy blanks.

[0055] In some embodiments, the hardness of the superhard tool is 59 to 65 HRC, for example, a range of 59 HRC, 60 HRC, 61 HRC, 62 HRC, 63 HRC, 64 HRC, 65 HRC, or any combination thereof. In this invention, the hardness of the superhard tool refers to the average hardness of the superhard tool, which is determined by randomly selecting five locations of the superhard tool and conducting hardness tests according to GB / T230.1-2018, and taking the average value as the hardness of the superhard tool.

[0056] This invention also provides a method for preparing the above-mentioned superhard tool, comprising the following steps: cutting and grinding a 60NiTi alloy slab to obtain a tool model; placing the tool model in a furnace at 1000~1100℃ and holding it for 60~180 min; water cooling; and grinding to obtain the superhard tool.

[0057] In the above system, heating and water cooling of the tool model helps to improve the hardness and other mechanical properties of the superhard tool.

[0058] Specifically, the tool model can be placed in a furnace and held at 1000~1100℃ (e.g., 1000℃, 1030℃, 1050℃, 1080℃, 1100℃ or any combination thereof) for 60~180 minutes (e.g., 60 minutes, 80 minutes, 100 minutes, 120 minutes, 150 minutes, 180 minutes or any combination thereof), then water-cooled and polished to obtain a superhard tool.

[0059] In practice, the process of cutting the 60NiTi alloy slab can be carried out using conventional methods in the field, such as wire cutting.

[0060] The present invention will be further described below through specific embodiments.

[0061] Example 1 Preparation of 60NiTi alloy slab S1: Prepare a billet with a thickness of 50mm, composed of the following components by mass percentage: Ni: 60.0%, Ti: 39.8%, Fe: 0.11%, O: 0.08%, N: 0.002%, C: 0.003%, H: 0.005%.

[0062] S2: Coat the surface of the billet with 1.5mm thick anti-oxidation glass powder to obtain the coated billet; S3: The coated blank is welded with the raw material side length as the welding point to encapsulate the coated blank in the first sleeve to obtain the first sleeve blank. Then, the surface of the first sleeve blank is coated with 1.5mm thick anti-oxidation glass powder, and the blank is welded with the welding points of the first sleeve staggered to encapsulate it in the second sleeve to obtain the second sleeve blank. The thickness of the first sleeve is 2mm, the thickness of the second sleeve is 8mm, and both the second sleeve and the second sleeve are steel sleeves.

[0063] S4: Forge the second cladding billet in one pass: Heat the empty furnace to 800℃, load the second cladding billet into the furnace and hold for 240 min, then heat to 975℃ for 30 min and hold for 300 min; preheat the hammer anvil to 300℃, flatten the second cladding billet after it comes out of the furnace with the full anvil, control the deformation speed to 15 mm / s and press it down until the finished product thickness δ=25 mm, place it in a 500℃ furnace and cool it to room temperature with the furnace.

[0064] S5: Use a grinding wheel to remove the first and second claddings to obtain a 60NiTi alloy slab. The surface of the 60NiTi alloy slab is intact and without cracks, and the thickness of the 60NiTi alloy slab is 22mm.

[0065] Preparation of superhard cutting tools The 60NiTi alloy slab was wire-cut and polished into a tool mold. The furnace was heated to 1030°C in an empty furnace, held at that temperature for 60 minutes, water-cooled, and polished to obtain a superhard tool.

[0066] Single-point hardness tests were performed on five random locations of the 60NiTi alloy slab in Example 1. The results are shown in Table 1. The single-point hardness of the 60NiTi alloy slab in Example 1 is close to the average hardness (i.e., the average value of the single-point hardness), indicating that the 60NiTi alloy slab in Example 1 has good uniformity.

[0067] In addition, metallographic microstructure tests were performed on the 60NiTi alloy slab in Example 1 at different locations according to GB / T13298-2015, and the results are shown in [Figure 1]. Figures 1-3,Depend on Figures 1-3 It can be seen that the 60NiTi alloy slab in Example 1 has good microstructure uniformity.

[0068] Table 1

[0069] Example 2 The preparation process of Example 2 is largely the same as that of Example 1. The difference is that in Example 2, the thickness of the second sheath is 4 mm and the thickness of the 60NiTi alloy slab is 23 mm. Other conditions and steps are the same as those in Example 1.

[0070] Example 3 The preparation process of Example 3 is largely the same as that of Example 1. The difference is that in Example 3, the thickness of the first sheath is 5 mm, the thickness of the second sheath is 20 mm, and the thickness of the 60NiTi alloy slab is 20 mm. Other conditions and steps are the same as those in Example 1.

[0071] Example 4 The preparation process of Example 4 is largely the same as that of Example 1. The difference is that in Example 4, the thickness of the first sheath is 3 mm, the thickness of the second sheath is 9 mm, and the thickness of the 60NiTi alloy slab is 22 mm. Other conditions and steps are the same as those in Example 1.

[0072] Example 5 The preparation process of Example 5 is largely the same as that of Example 1. The difference is that in Example 5, the hollow furnace in S4 is heated to 750°C, the second packaged billet is loaded into the furnace and held for 240 min, and then the temperature is raised to 975°C for 30 min and held for 300 min. Other conditions and steps are the same as those in Example 1.

[0073] Example 6 The preparation process of Example 6 is largely the same as that of Example 1. The difference is that in Example 6, the hollow furnace in S4 is heated to 850°C, the second packaged billet is loaded into the furnace and held for 300 min, and then the temperature is raised to 975°C for 30 min and held for 300 min. Other conditions and steps are the same as those in Example 1.

[0074] Example 7 The preparation process of Example 7 is largely the same as that of Example 1. The difference is that in Example 7, the hollow furnace in S4 is heated to 800°C, the second packaged billet is loaded into the furnace and held for 240 min, and then the temperature is raised to 880°C for 30 min and held for 300 min. Other conditions and steps are the same as those in Example 1.

[0075] Example 8 The preparation process of Example 8 is largely the same as that of Example 1. The difference is that in Example 8, the hollow furnace in S4 is heated to 800°C, the second packaged billet is loaded into the furnace and held for 240 min, and then the temperature is raised to 1000°C for 30 min and held for 480 min. Other conditions and steps are the same as those in Example 1.

[0076] Example 9 The preparation process of Example 9 is largely the same as that of Example 1, except that in Example 9, the deformation speed in S4 is 18 mm / s, and the other conditions and steps are the same as those in Example 1.

[0077] Example 10 The preparation process of Example 10 is largely the same as that of Example 1, except that the deformation speed in Example 10 is 20 mm / s, while the other conditions and steps are the same as those in Example 1.

[0078] Comparative Example 1 The preparation process is largely the same as in Example 1, except that the first and second sheaths are not used, while the other steps and conditions remain basically the same. Cracking occurs during the forging process of the billet.

[0079] Comparative Example 2 The preparation process is largely the same as in Example 1, except that in S3, the coated blank is only encapsulated in the first sleeve and there is no second sleeve. Other conditions and steps are the same as in Example 1. The edges and center of the forged 60NiTi alloy slab are severely cracked.

[0080] Comparative Example 3 The preparation process was largely the same as in Example 1, except that in S4, no two-step heating was performed, and the second cladding blank was only held at 975°C for 300 minutes. Other conditions and steps were the same as in Example 1. The surface of the forged 60NiTi alloy slab was severely cracked.

[0081] Comparative Example 4 The preparation process is largely the same as in Example 1, except that anti-oxidation glass powder is not applied, while other steps and conditions remain basically the same. After forging, the first and second sheaths and the billet in the finished product are severely adhered together, making it difficult to remove the first and second sheaths.

[0082] The thicknesses of the first sheath, the second sheath, the ratio of the second sheath thickness to the first sheath thickness (i.e., the second sheath thickness / first sheath thickness in Table 2), the thickness of the high-temperature anti-oxidation lubricating coating in S2 (i.e., the S2 coating thickness in Table 2), the thickness of the high-temperature anti-oxidation lubricating coating in S3 (i.e., the S3 coating thickness in Table 2), the forming condition of the 60NiTi alloy slab (i.e., the slab forming condition in Table 2), the hardness of the 60NiTi alloy slab, the hardness deviation of the 60NiTi alloy slab, and the hardness of the superhard cutting tool in each embodiment and comparative example are summarized in Table 2.

[0083] Table 2

[0084] Compared to Comparative Examples 1-4, Examples 1-10 involved coating the billet surface with a high-temperature anti-oxidation lubricating coating and using a double-layer sheath (the first and second sheaths encapsulate the billet). A two-step heating process was employed for single-fire forging, successfully producing 60NiTi alloy billets and superhard cutting tools with good surface conditions. Furthermore, the 60NiTi alloy billets and superhard cutting tools in Examples 1-10 exhibited high hardness and good uniformity. For example, the hardness of the 60NiTi alloy billet was 20-30 HRC with a hardness deviation of 3%-9%, and the hardness of the superhard cutting tool was 59-65 HRC.

[0085] Furthermore, compared to Examples 2 and 3, Examples 1 and 4 further control (blank thickness × 15% - first sleeve thickness) ≤ second sleeve thickness ≤ (blank thickness × 25% - first sleeve thickness), further reducing the hardness deviation of the 60NiTi alloy slab and improving the uniformity and performance consistency of the 60NiTi alloy slab.

[0086] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. A short-process preparation method for 60NiTi alloy slabs, characterized in that, Includes the following steps: S1. Prepare the blank; S2. A high-temperature anti-oxidation and lubricating coating is applied to the surface of the blank to obtain a coated blank; S3. The coated blank is encapsulated in a first sleeve to obtain a first sleeve blank. The surface of the first sleeve blank is then coated with the high-temperature anti-oxidation lubricating coating and encapsulated in a second sleeve to obtain a second sleeve blank. S4. The second cladding blank is forged in one heat using a two-step heating process. S5. Remove the first and second claddings to obtain the 60NiTi alloy slab; The ratio of the thickness of the second sheath to the thickness of the first sheath is 2 to 4.

2. The short-process preparation method for 60NiTi alloy slabs according to claim 1, characterized in that, The thickness of the second sheath satisfies the following condition: (the thickness of the blank × 15% - the thickness of the first sheath) ≤ the thickness of the second sheath ≤ (the thickness of the blank × 25% - the thickness of the first sheath).

3. The short-process preparation method for 60NiTi alloy slabs according to claim 1 or 2, characterized in that, The thickness of the first sheath is 2~5mm.

4. The short-process preparation method for 60NiTi alloy slabs according to claim 1 or 2, characterized in that, The thickness of the second sleeve is 4~20mm.

5. The short-process preparation method for 60NiTi alloy slabs according to claim 1, characterized in that, The process of forging the second cladding billet in S4 using a two-step heating method in one pass includes: S41. Place the second-encased billet in the furnace at 750~850℃ and hold for 240~300 minutes. S42. Then, within 30-60 minutes, raise the temperature to 850-1000℃; hold at that temperature for 300-480 minutes. S43. Perform controlled-speed forging, and after forging to the finished product, place it in a furnace at 500~600℃ for furnace cooling.

6. The short-process preparation method for 60NiTi alloy slabs according to claim 5, characterized in that, The deformation speed of the controlled-speed forging in the S43 is 15~20mm / s.

7. A 60NiTi alloy slab, characterized in that, The 60NiTi alloy slab was prepared using the short-process preparation method according to any one of claims 1-6.

8. A superhard cutting tool, characterized in that, The 60NiTi alloy slab is prepared by the short-process preparation method of any one of claims 1-6 or by processing the 60NiTi alloy slab as described in claim 7.

9. A method for preparing a superhard cutting tool according to claim 8, characterized in that, The process includes the following steps: cutting and grinding the 60NiTi alloy slab to obtain a tool model; placing the tool model in a furnace at 1000~1100℃ for 60~180 minutes; water cooling; and grinding to obtain a superhard tool.

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