High-strength and high-toughness alloy material as well as preparation method and application thereof

Abstract

The invention relates to a high-strength and high-toughness alloy material and a preparation method and application thereof, and particularly belongs to the technical field of alloy material preparation, the alloy material is composed of a hard alloy outer ring and an iron alloy inner ring, and the hard alloy outer ring is prepared from, by mass, 65%-68% of WC, 18%-20% of Co, 10%-12% of Ni, 0.5%-0.8% of mischmetal and 2.0%-3.0% of composite carbide; raw materials of the iron alloy inner ring comprise the following components in percentage by mass: 18%-22% of TiC, 4.0%-5.0% of Cr, 7.5%-8.5% of W, 3.5%-4.5% of Mo, 0.8%-1.2% of V, 1.5%-2.0% of Ni and the balance of iron. Through gradient compounding of WC and other refractory carbides and process optimization, densification and grain control can be better balanced, and synergistic improvement of high hardness and high toughness is achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of alloy material preparation, and more specifically, to a high-strength and high-toughness alloy material and a preparation method and application thereof. Background Art

[0002] In the fields of aerospace, mining machinery, high-speed rolling, etc., the requirements for the comprehensive performance of materials are becoming increasingly stringent, especially wear-resistant and impact-resistant materials with high hardness, high toughness and excellent heat resistance. Although traditional cemented carbide has excellent wear resistance, its toughness is insufficient and it is prone to brittle fracture when subjected to impact loads. Although single iron-based alloys such as high-entropy alloys and stainless steel have certain toughness, their hardness and wear resistance are difficult to meet the requirements of extreme working conditions. In recent years, composite structural materials have become a research hotspot, but the existing technology still has the following key problems: Cemented carbide increases hardness by reducing the content of the binder phase, but this results in a significant decrease in fracture toughness and is unable to adapt to dynamic load environments. After the introduction of carbides to inhibit grain growth and strengthen the alloy matrix, some alloys are prone to crack deflection failure, but excessive addition will destroy the fluidity of liquid phase sintering and form pore defects. In addition, it is difficult to achieve effective diffusion bonding between carbides and the iron matrix in the preparation process, and there are often pores or brittle phases at the interface, leading to interlayer delamination and reduced mechanical properties.

[0003] Based on the above statements, the present invention provides a high-strength and high-toughness alloy material and a preparation method and application thereof. Summary of the invention

[0004] In order to solve the above-mentioned problems, the present invention provides a high-strength and high-toughness alloy material and a preparation method and application thereof. The specific technical solution is as follows: A high-strength and high-toughness alloy material, composed of a cemented carbide outer ring and an iron alloy inner ring, wherein the cemented carbide outer ring raw material comprises the following components by mass percentage: 65-68% WC, 18-20% Co, 0.5-0.8% mixed rare earth, 2.0-3.0% composite carbide, and the balance is Ni; The ferroalloy inner ring raw material includes the following components in percentage by mass: 18-22% TiC, 4.0-5.0% Cr, 7.5-8.5% W, 3.5-4.5% Mo, 0.8-1.2% V, 1.5-2.0% Ni, and the balance is iron.

[0005] In the above technical solution, composite carbides are added to the components of the cemented carbide outer ring to improve hardness and wear resistance; at the same time, the ratio of Co and Ni in the system is adjusted, and through the subsequent design of the pretreatment process and sintering process, the formation of Ni-Co alloy in the system is promoted, and its effect as a binder phase is promoted, further improving toughness and bonding strength. In the ferroalloy inner ring, the contents of TiC, Cr, W, Mo and Ni are optimized to balance the strength and toughness of the ferroalloy inner ring.

[0006] Further, the mixed rare earth is obtained by mixing Ce, La and Pr according to the mass ratio of (55 - 60):(30 - 35):(3 - 5).

[0007] Further, the composite carbide is obtained by mixing VC and other refractory carbides.

[0008] Further, the other refractory carbide is TaC and / or NbC.

[0009] Preferably, the mass ratio of VC to other refractory carbides is (1.5 - 2.0):(0.5 - 1.0).

[0010] The present invention also provides a preparation method of a high-strength and high-toughness alloy material, which specifically includes the following steps: S1. Ball-mill the raw materials of the cemented carbide outer ring with a planetary ball mill, with a ball-to-material ratio of 3:1, add anhydrous ethanol and stearic acid, and set the ball-milling time to 3.5 - 4 hours; then dry at 90 - 100 °C for 10 - 12 hours, and pass through a 200 - 300 mesh sieve to obtain the cemented carbide outer ring powder; S2. Ball-mill the raw materials of the ferroalloy inner ring with a planetary ball mill, with a ball-to-material ratio of 4:1, add anhydrous ethanol and stearic acid, and set the ball-milling time to 4 - 6 hours; then dry at 90 - 100 °C for 10 - 12 hours, and pass through a 300 - 400 mesh sieve to obtain the ferroalloy inner ring powder; S3. Prepare a double-layer jacket mold, load the cemented carbide outer ring powder into the outer jacket, and load the ferroalloy inner ring powder into the inner jacket, and perform pre-pressing treatment by cold isostatic pressing; then transfer it to a vacuum hot-pressing sintering furnace for sintering treatment, and perform pressure treatment by hot isostatic pressing. After pressurization, cool at a rate of 1 - 5 °C per minute to 500 - 520 °C, and then cool with the furnace to room temperature to obtain a high-strength and high-toughness alloy material.

[0011] Further, in step S1, the mass ratio of the raw materials of the cemented carbide outer ring, anhydrous ethanol and stearic acid is (300 - 400):100:(0.3 - 0.7).

[0012] Further, in step S2, the mass ratio of the ferroalloy inner ring raw material, absolute ethanol, and stearic acid is (300 - 400):100:(0.3 - 0.5).

[0013] Further, in step S3, the pressure for the pre-pressing treatment is set to 200 - 250 Mpa, and the pressure holding time is 15 - 20 minutes.

[0014] Further, in step S3, the specific operations for the sintering treatment and the pressure application treatment are as follows: Under vacuum conditions, the temperature is raised to 500 - 520 °C at a rate of 5 - 10 °C per minute, held for 30 - 60 minutes, then the temperature is further raised to 800 - 850 °C at a rate of 10 - 20 °C per minute and held for 45 - 60 minutes. An inert gas is filled into the system and pressure application is started, with the pressure set to 4 - 5 Mpa, the temperature is raised to 1200 - 1300 °C, and held under pressure for 80 - 100 minutes. Subsequently, the pressure is raised to 7 - 9 Mpa and the temperature is raised to 1300 - 1350 °C, and held under pressure for 100 - 120 minutes.

[0015] The third object of the present invention is to provide the application of the above-mentioned high-strength and high-toughness alloy material in a roll structure.

[0016] In summary, the present invention has the following beneficial effects: 1. In the technical solution of the present invention, by optimizing the respective component settings of the cemented carbide outer ring and the ferroalloy inner ring, the performance of the final alloy material is improved. In the cemented carbide outer ring, WC is used as the main hard phase skeleton, which forms a solid solution with Co and Ni in the formula to inhibit the abnormal growth of WC grains under high WC content, maintain a fine grain structure in the components, and improve the thermal fatigue resistance of the matrix. And composite carbides are used to strengthen the matrix. VC improves wear resistance, and other refractory carbides enhance high-temperature stability. At the same time, VC can form a solid solution with WC, and cooperate with other refractory carbides to hinder dislocation movement, synergistically improving the hardness and creep resistance of the material. The Co and Ni components, on the one hand, act as the binder phase, optimizing the fluidity during liquid-phase sintering, promoting the metallurgical bonding between the outer ring and the inner ring, and enhancing the interfacial bonding strength. On the other hand, they act together with the mixed rare earths. The mixed rare earths form a liquid phase at high temperatures, promoting element diffusion and interfacial wetting, purifying the grain boundaries by removing impurities such as oxygen and sulfur, and the Co-Ni complex inhibits the segregation of composite carbides, further improving the material strength. In the ferroalloy inner ring components, the iron matrix is used as the main hard phase, and TiC is used as the second hard phase. TiC forms a Ti(C,N)-Fe eutectic phase with iron, enhancing the interfacial metallurgical bonding, and through component optimization, improving the mechanical properties and interfacial bonding effect of the ferroalloy inner ring. During the sintering process, the liquid phase of Co promotes the mutual diffusion of TiC and Fe to form a metallurgical bond, and forms a double binder phase system with Ni in the inner ring, synergistically improving the comprehensive performance. The WC in the outer ring and the TiC in the inner ring form a composite hard phase. At the same time, the Ni-Co alloy in the outer ring and the Fe matrix in the inner ring form a transition layer through diffusion, enhancing the interlayer bonding strength. The outer cemented carbide provides high hardness, and the inner ferroalloy ensures high toughness, finally obtaining a high-strength and high-toughness alloy material.

[0017] 2. In the technical solution of the present invention, by setting different ball milling treatment procedures for the raw materials of the cemented carbide outer ring and the ferroalloy inner ring, a high-strength and high-toughness alloy material is formed. A higher ball-to-material ratio and ball milling time are set for the raw materials of the ferroalloy inner ring to promote the bonding effect between the outer ring material and the inner ring material. For the cemented carbide outer ring, setting a lower-strength ball milling procedure can avoid excessive crushing of hard particles, maintain its high hardness characteristics, and prevent excessive refinement of binder phases such as Co and Ni, ensuring the liquid phase formation ability during subsequent sintering. For the ferroalloy inner ring, since the hardness of the iron-based powder is low, in order to enhance the dispersion uniformity of complex components such as TiC, W, and Mo, it is necessary to improve the grinding efficiency to adapt to the outer ring material and avoid composition segregation.

[0018] 3. In the technical solution of the present invention, a pre-pressing treatment procedure, a sintering treatment, and a pressure treatment procedure are provided in the specific preparation process of the high-strength and high-toughness alloy material. Through the pre-pressing treatment, the alloy material is preliminarily formed. The Co-Ni bonding phase in the outer ring is preliminarily formed into a liquid-phase network during pre-pressing, and the Fe matrix in the inner ring forms a uniform structure through pre-pressing, avoiding the segregation of TiC and ensuring that the powder does not displace during subsequent sintering. Through the sintering and pressure treatment with a temperature gradient, the organic residues are fully removed at 500 - 520 °C to avoid the generation of pores subsequently. Then, the temperature is raised to the solid-phase sintering temperature (800 - 850 °C) to promote element diffusion and the formation of the Co-Ni liquid phase. The temperature is continuously raised and pressure is applied to promote the wetting of WC particles by the Co-Ni liquid phase and its diffusion into the inner-ring Fe matrix, promoting the eutectic metallurgical bonding of the Co-Ni liquid phase and TiC-Fe, and ensuring the interlayer reliability. Finally, the temperature and pressure are continuously raised and treated to promote the deformation of each component to eliminate residual pores, improve the density, and fill microcracks. Detailed implementation mode

[0019] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without making creative efforts belong to the protection scope of the present invention.

[0020] Embodiment 1 A high-strength and high-toughness alloy material is composed of a cemented carbide outer ring and a ferroalloy inner ring. Among them, the raw materials of the cemented carbide outer ring, calculated by mass percentage, include the following components: 65% WC, 18% Co, 0.5% mixed rare earths, 2.0% composite carbide, and the balance is Ni; the mixed rare earths are obtained by mixing Ce, La, and Pr in a mass ratio of 55:30:3; the composite carbide is obtained by mixing VC and other refractory carbides, and the mass ratio of VC to other refractory carbides is 1.5:0.5, and the other refractory carbide is TaC.

[0021] The raw materials of the ferroalloy inner ring, calculated by mass percentage, include the following components: 18% TiC, 4.0% Cr, 7.5% W, 3.5% Mo, 0.8% V, 1.5% Ni, and the balance is iron.

[0022] The preparation method of the above high-strength and high-toughness alloy material includes the following steps: S1. The raw materials of the cemented carbide outer ring are ball-milled by a planetary ball mill with a ball-to-material ratio of 3:1, anhydrous ethanol and stearic acid are added, and the ball-milling time is set to 3.5 hours; then it is dried at 90 °C for 10 hours and sieved through a 200-mesh sieve to obtain the cemented carbide outer ring powder; the mass ratio of the raw materials of the cemented carbide outer ring, anhydrous ethanol, and stearic acid is 300:100:0.3; S2. The ferroalloy inner ring raw materials are ball-milled using a planetary ball mill with a ball-to-material ratio of 4:1. Anhydrous ethanol and stearic acid are added, and the ball-milling time is set to 4 hours. Subsequently, it is dried at 90 °C for 10 hours and sieved through a 300-mesh sieve to obtain ferroalloy inner ring powder. The mass ratio of the ferroalloy inner ring raw materials, anhydrous ethanol, and stearic acid is 300:100:0.3.

[0023] S3. Prepare a double-layer jacket mold. Load the cemented carbide outer ring powder into the outer jacket and the ferroalloy inner ring powder into the inner jacket, and perform pre-pressing treatment by cold isostatic pressing. The pressure of the pre-pressing treatment is set to 200 Mpa, and the pressure holding time is 15 minutes. Subsequently, it is transferred to a vacuum hot pressing sintering furnace for sintering treatment and pressurized by hot isostatic pressing. The specific operation is as follows: Set the vacuum degree to 1×10 -3 Pa, heat it to 500 °C at a rate of 5 °C / minute, hold the temperature for 30 minutes, then continue to heat it to 800 °C at a rate of 10 °C / minute, hold the temperature for 45 minutes, fill the system with inert gas and start pressurizing, set the pressure to 4 Mpa, raise the temperature to 1200 °C, hold the temperature and pressure for 80 minutes, then raise the pressure to 7 Mpa and raise the temperature to 1300 °C, hold the temperature and pressure for 100 minutes. After pressurizing, cool it to 500 °C at a rate of 3 °C / minute, and then cool it to room temperature with the furnace, thus obtaining a high-strength and high-toughness alloy material.

[0024] Example 2 A high-strength and high-toughness alloy material is composed of a cemented carbide outer ring and a ferroalloy inner ring. Among them, the cemented carbide outer ring raw materials, by mass percentage, include the following components: 67% WC, 19% Co, 0.7% mixed rare earths, 2.5% composite carbide, and the balance is Ni. The mixed rare earths are obtained by mixing Ce, La, and Pr in a mass ratio of 58:33:4. The composite carbide is obtained by mixing VC and other refractory carbides, and the mass ratio of VC to other refractory carbides is 1.8:0.8. The other refractory carbide is TaC.

[0025] The ferroalloy inner ring raw materials, by mass percentage, include the following components: 20% TiC, 4.5% Cr, 8.0% W, 4.0% Mo, 1.0% V, 1.8% Ni, and the balance is iron.

[0026] The preparation method of the above high-strength and high-toughness alloy material includes the following steps: S1. The cemented carbide outer ring raw materials are ball-milled using a planetary ball mill with a ball-to-material ratio of 3:1. Anhydrous ethanol and stearic acid are added, and the ball-milling time is set to 4 hours. Subsequently, it is dried at 90 °C for 12 hours and sieved through a 300-mesh sieve to obtain cemented carbide outer ring powder. The mass ratio of the cemented carbide outer ring raw materials, anhydrous ethanol, and stearic acid is 350:100:0.5; S2. Ball mill the ferroalloy inner ring raw materials using a planetary ball mill with a ball-to-material ratio of 4:1. Add absolute ethanol and stearic acid, and set the ball milling time to 5 hours. Then dry at 100 °C for 12 hours, and pass through a 400-mesh sieve to obtain ferroalloy inner ring powder. The mass ratio of the ferroalloy inner ring raw materials, absolute ethanol, and stearic acid is 350:100:0.4.

[0027] S3. Prepare a double-layer jacket mold. Load the cemented carbide outer ring powder into the outer jacket, and load the ferroalloy inner ring powder into the inner jacket. Perform pre-pressing treatment by cold isostatic pressing, with the pre-pressing pressure set to 230 Mpa and the pressure holding time to 20 minutes. Then transfer it to a vacuum hot pressing sintering furnace for sintering treatment, and perform pressure increasing treatment by hot isostatic pressing. The specific operation is as follows: Set the vacuum degree to 1×10 -3 Pa, heat up to 510 °C at a rate of 10 °C / minute, hold for 45 minutes, then continue to heat up to 830 °C at a rate of 15 °C / minute, hold for 55 minutes. Fill the system with inert gas and start pressurizing, with the pressure set to 5 Mpa, raise the temperature to 1270 °C, hold the pressure and temperature for 90 minutes, then raise the pressure to 8 Mpa and raise the temperature to 1330 °C, hold the pressure and temperature for 120 minutes. After pressurizing, cool to 510 °C at a rate of 5 °C / minute, and then cool with the furnace to room temperature to obtain a high-strength and high-toughness alloy material.

[0028] Example 3 A high-strength and high-toughness alloy material consists of a cemented carbide outer ring and a ferroalloy inner ring. Among them, the cemented carbide outer ring raw materials, by mass percentage, include the following components: 68% WC, 20% Co, 0.8% mixed rare earths, 3.0% composite carbide, and the balance is Ni. The mixed rare earths are obtained by mixing Ce, La, and Pr in a mass ratio of 60:35:5. The composite carbide is obtained by mixing VC and other refractory carbides, and the mass ratio of VC to other refractory carbides is 2:1. The other refractory carbide is NbC.

[0029] The ferroalloy inner ring raw materials, by mass percentage, include the following components: 22% TiC, 5.0% Cr, 8.5% W, 4.5% Mo, 1.2% V, 2.0% Ni, and the balance is iron.

[0030] The preparation method of the above high-strength and high-toughness alloy material includes the following steps: S1. Ball mill the cemented carbide outer ring raw materials using a planetary ball mill with a ball-to-material ratio of 3:1. Add absolute ethanol and stearic acid, and set the ball milling time to 4 hours. Then dry at 100 °C for 12 hours, and pass through a 300-mesh sieve to obtain cemented carbide outer ring powder. The mass ratio of the cemented carbide outer ring raw materials, absolute ethanol, and stearic acid is 400:100:0.7; S2. Ball mill the ferroalloy inner ring raw materials using a planetary ball mill with a ball-to-material ratio of 4:1. Add absolute ethanol and stearic acid, and set the ball milling time to 6 hours. Then dry at 100 °C for 12 hours, and pass through a 400-mesh sieve to obtain ferroalloy inner ring powder. The mass ratio of the ferroalloy inner ring raw materials, absolute ethanol, and stearic acid is 400:100:0.5.

[0031] S3. Prepare a double-layer jacket mold. Load the cemented carbide outer ring powder into the outer jacket and the ferroalloy inner ring powder into the inner jacket, and perform pre-pressing treatment by cold isostatic pressing. The pressure of the pre-pressing treatment is set to 250 Mpa, and the pressure holding time is 20 minutes. Then transfer it to a vacuum hot pressing sintering furnace for sintering treatment, and perform pressure increasing treatment by hot isostatic pressing. The specific operation is as follows: Set the vacuum degree to 1×10 -3 Pa, heat up to 520 °C at a rate of 10 °C / minute, hold for 60 minutes, then continue to heat up to 850 °C at a rate of 20 °C / minute, hold for 60 minutes, fill the system with inert gas and start to increase the pressure. The pressure is set to 5 Mpa, raise the temperature to 1300 °C, hold the pressure and temperature for 100 minutes, then raise the pressure to 9 Mpa and raise the temperature to 1350 °C, hold the pressure and temperature for 120 minutes. After pressurization, cool to 520 °C at a rate of 5 °C / minute, and then cool to room temperature with the furnace, thus obtaining a high-strength and high-toughness alloy material.

[0032] Comparative Example 1 The difference between this comparative example and Example 1 is that in the cemented carbide outer ring raw materials, the composite carbide is obtained by mixing VC and TiC in a mass ratio of 1.5:0.5.

[0033] Comparative Example 2 The difference between this comparative example and Example 1 is that in the composite carbide of the cemented carbide outer ring raw materials, the mass ratio of VC to other refractory carbides is 5:1.

[0034] Comparative Example 3 The difference between this comparative example and Example 1 is that in steps S1 and S2 of this comparative example, the same ball milling process is used for the cemented carbide outer ring raw materials and the ferroalloy inner ring raw materials. Specifically, in the ball milling process, the ball-to-material ratio is set to 4:1, absolute ethanol and stearic acid are added, and the ball milling time is set to 4 hours. Then dry at 90 °C for 10 hours and pass through a 300-mesh sieve. The mass ratio of the cemented carbide outer ring raw materials or the ferroalloy inner ring raw materials, absolute ethanol, and stearic acid is 300:100:0.3.

[0035] Comparative Example 4 The difference between this comparative example and Example 1 is that in step S3 of this comparative example, no pre-pressing treatment is set, and it is directly transferred to a vacuum hot pressing sintering furnace for sintering treatment, and pressure increasing treatment is performed by hot isostatic pressing.

[0036] Comparative Example 5 The difference between this comparative example and Example 1 lies in that in step S3 of this comparative example, it is transferred to a vacuum hot pressing sintering furnace for sintering treatment, and hot isostatic pressing is used for pressure treatment. The specific operation is as follows: Set the vacuum degree to 1×10 -3 Pa, heat up to 500°C at a rate of 5°C per minute, hold for 30 minutes, then fill the system with inert gas and start pressurizing. The pressure is set to 7 Mpa, raise the temperature to 1300°C, and hold the pressure for 225 minutes; after pressurizing, cool to 500°C at a rate of 3°C per minute, and then cool with the furnace to room temperature.

[0037] Performance Test The high-strength and high-toughness alloy materials prepared in Examples 1-3 and Comparative Examples 1-5 of the present invention are made into samples with a size of 75*Φ10, and the performance of the products in the group is tested. The specific test methods are as follows: Hardness Test: Referring to the method in ISO 3738, the Rockwell hardness of the product is tested, and the test load is set to 10 kgf; Flexural Strength Test: Referring to the method in ISO 3327, the flexural strength of the product is tested by a three-point bending test. The span is set to 30 mm, and the loading rate is 0.5 mm / min; Wear Loss Test: Referring to the method in ASTM G65, the wear loss of the product is tested by an abrasive wear test. The test load is set to 10 N, the grinding wheel: SiC (particle size 60 mesh), and the wear distance: 1000 m; Fracture Toughness Test: Referring to the method described in GB∕T 21143-2014, the fracture toughness of the product is tested, and the indentation load is set to 200 N.

[0038] The specific performance test results are shown in Table 1 below: Table 1 Performance Test Results of High-Strength and High-Toughness Alloy Materials Prepared in Examples and Comparative Examples

[0039] It can be seen from the results shown in Table 1 above that: Through WC-other refractory carbide gradient composite and process optimization, Examples 1-3 are significantly superior to the comparative examples in terms of hardness, strength, wear resistance and toughness, verifying the importance of the synergy of component design and process parameters. Examples 1-3 achieve the balance of hardness and toughness through WC-other refractory carbide composite and Ni-Co double binder phases, and are suitable for high-end roll materials. Due to composition or process defects, the performance of Comparative Examples 1-5 has decreased significantly. For example, the hardness of Comparative Example 4 is only 63 HRA, and the toughness of Comparative Example 3 is only 52 MPa·m 1 / 2 , verifying the necessity of the synergy of components and processes.

[0040] Specifically, from the results in Comparative Example 1, it can be seen that using titanium carbide to reinforce the matrix instead of other refractory carbides, the hardness of TiC is lower than that of other refractory carbides such as NbC and TaC, and there is a lattice mismatch with WC, resulting in the weakening of the synergistic effect of the composite hard phase, being unable to significantly hinder dislocation movement, and the wear resistance improvement being limited, and the effect is not as good as the compounding effect of VC with TaC and NbC.

[0041] From the results in Comparative Example 2, it can be seen that the proportion of the composite carbide VC is too high, and VC forms an excessive solid solution with WC, resulting in insufficient refinement of WC grains. Moreover, VC occupies too much space in the Co-Ni binder phase, reducing the fluidity of the liquid phase and increasing the content of V 2 O 5 in the system, damaging the protective layer. Therefore, the hardness of the final alloy material is slightly increased, but the toughness is significantly decreased, and the impact resistance deteriorates.

[0042] In Comparative Example 3, the finer-grained powder of the outer ring of the cemented carbide can promote the densification effect of the structure and reduce pore defects. However, in the solution of the present invention, components such as TiC, as part of the alloy material, are not differentially treated, resulting in problems of segregation and stress concentration, and the compatibility with the inner ring material can better improve the overall strength performance of the material.

[0043] In Comparative Example 4 and Comparative Example 5, the pre-pressing treatment can better fix the powder body and amplify the effects of gradient heat treatment and pressure treatment. Through gradient sintering and pressure treatment, the densification and grain control can be better balanced, realizing the synergistic improvement of high hardness and high toughness.

[0044] In the description of the specification, the description referring to terms such as "one embodiment", "example", "specific example", etc. means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in a suitable manner in any one or more embodiments or examples.

[0045] The above content is only an example and illustration of the present invention. Those skilled in the art of the present technology make various modifications or supplements to the described specific embodiments or use similar ways to replace them. As long as they do not deviate from the invention or exceed the scope defined by the claims of the present invention, they should fall within the protection scope of the present invention.

Claims

1. A high-strength and high-toughness alloy material, characterized in that: It is composed of a cemented carbide outer ring and an iron alloy inner ring. The cemented carbide outer ring raw material includes the following components by mass percentage: 65-68% WC, 18-20% Co, 0.5-0.8% mixed rare earth, 2.0-3.0% composite carbide, and the balance is Ni; The ferroalloy inner ring raw material includes the following components in percentage by mass: 18-22% TiC, 4.0-5.0% Cr, 7.5-8.5% W, 3.5-4.5% Mo, 0.8-1.2% V, 1.5-2.0% Ni, and the balance is iron.

2. A high-strength and high-toughness alloy material according to claim 1, characterized in that: The mixed rare earth is obtained by mixing Ce, La and Pr in a mass ratio of (55-60): (30-35): (3-5).

3. A high-strength and high-toughness alloy material according to claim 1, characterized in that: The composite carbide is obtained by mixing VC and other refractory carbides.

4. A high-strength and high-toughness alloy material according to claim 3, characterized in that: The other refractory carbides are TaC and / or NbC.

5. A method for preparing a high-strength and high-toughness alloy material as claimed in any one of claims 1 to 4, characterized in that: The specific steps include: S1. Ball-milling the cemented carbide outer ring raw material, adding anhydrous ethanol and stearic acid, setting the ball-milling time to 3.5-4 hours; then drying at 90-100° C. for 10-12 hours, and passing through a 200-300 mesh sieve to obtain a cemented carbide outer ring powder; S2, ball-milling the ferroalloy inner ring raw material, adding anhydrous ethanol and stearic acid, setting the ball-milling time to 4-6 hours; then drying at 90-100° C. for 10-12 hours, and passing through a 300-400 mesh sieve to obtain the ferroalloy inner ring powder; S3. Prepare a double-layer sheath mold, load the cemented carbide outer ring powder into the outer ring sheath, load the ferroalloy inner ring powder into the inner sheath, and perform pre-pressing treatment by cold isostatic pressing; then transfer to a vacuum hot pressing sintering furnace for sintering treatment, and perform pressurization treatment by hot isostatic pressing. After pressurization, cool to 500-520℃ at a rate of 1-5℃ / min, and then cool to room temperature with the furnace to obtain a high-strength and high-toughness alloy material.

6. The method for preparing a high-strength and high-toughness alloy material according to claim 5, characterized in that: In step S1, the mass ratio of the cemented carbide outer ring raw material, anhydrous ethanol and stearic acid is (300-400):100:(0.3-0.7).

7. The method for preparing a high-strength and high-toughness alloy material according to claim 5, characterized in that: In step S2, the mass ratio of the ferroalloy inner ring raw material, anhydrous ethanol and stearic acid is (300-400):100:(0.3-0.5).

8. The method for preparing a high-strength and high-toughness alloy material according to claim 5, characterized in that: In step S3, the pre-pressing pressure is set to 200-250 MPa, and the holding time is 15-20 minutes.

9. The method for preparing a high-strength and high-toughness alloy material according to claim 5, characterized in that: In step S3, the specific operations of sintering and pressurizing are as follows: Under vacuum conditions, the temperature is increased to 500-520°C at a rate of 5-10°C / min, and kept warm for 30-60 minutes. The temperature is then increased to 800-850°C at a rate of 10-20°C / min, and kept warm for 45-60 minutes. Inert gas is introduced into the system and pressurization is started. The pressure is set to 4-5Mpa, the temperature is increased to 1200-1300°C, and the temperature is kept warm for 80-100 minutes. The pressure is then increased to 7-9Mpa, the temperature is increased to 1300-1350°C, and the temperature is kept warm for 100-120 minutes.

10. Use of the high-strength and high-toughness alloy material according to any one of claims 1 to 4 in a rolling mill structure.

Images