Co-Ni-Cr-Al-Ti adhesive hard alloy and preparation method thereof

Abstract

The invention belongs to the technical field of hard alloy materials, and particularly relates to a Co-Ni-Cr-Al-Ti adhesive hard alloy and a preparation method thereof. In a WC-Co-Ni-Cr-Al hard alloy material, gamma '-phase (Ni, Co) 3Al is precipitated and separated out from a Co-Ni-Cr-Al adhesive as a main mechanism for strengthening the performance of the hard alloy material, a certain amount of Ti is added on the basis, the Co-Ni-Cr-Al-Ti adhesive is designed, and the effect of solid solution strengthening of the gamma'-phase is achieved due to the fact that Ti can be dissolved into the gamma '-phase, so that the performance of the hard alloy material is strengthened. According to the method, the self-strengthening effect of the gamma'phase is reserved, meanwhile, the gamma 'phase is strengthened, and finally the mechanical property stability of the whole hard alloy material is improved.

Description

Technical Field

[0001] This invention belongs to the field of cemented carbide materials technology, specifically relating to a Co-Ni-Cr-Al-Ti binder cemented carbide with improved thermal shock resistance and its preparation method. Background Technology

[0002] Cemented carbide is a composite material prepared by powder metallurgy, using refractory metal compound WC as the backbone and one or more transition metals such as Co, Ni, and Fe as binders. Due to its high strength, high hardness, and excellent wear resistance and high-temperature resistance, it is widely used in military, aerospace, oil drilling, and cutting industries. In the rolling production of bars, wires, special steels, and rebars, cemented carbide rolls significantly improve rolling efficiency compared to traditional cast iron rolls, making it one of the important application areas for cemented carbide materials.

[0003] The earliest WC-Co cemented carbide roll rings, despite their good stability and reliability, could reach temperatures close to 80% of their liquidus eutectic temperature when in contact with hot steel. Advanced foreign companies have widely adopted Co-Ni-Cr as a binder for their new generation of high-speed wire rod roll rings. These advanced foreign roll ring grades primarily improve the oxidation and corrosion resistance of the binder phase by adding Ni and a small amount of Cr. This allows WC-Ni-Co-Cr to exhibit significantly higher wear resistance and high-temperature oxidation resistance than WC-Co alloys, while maintaining comparable strength and hardness. Using WC-Ni-Co-Cr cemented carbide roll rings not only improves the surface quality of the rolled material but also enhances the high-temperature stability and corrosion resistance of the roll rings, making them suitable for a wider range of operating conditions.

[0004] In recent years, the country has attached great importance to energy conservation and emission reduction in the steel industry and encouraged the steel industry to introduce new technologies. In 2018, the country implemented the new standard GB / T1499.2-2018 for steel bar enterprises, replacing GB / T1499.2-2007. The rolling of rebar can no longer achieve high strength through forced water cooling, so as to avoid the formation of closed martensite structure. At the same time, in order to reduce the amount of alloying elements and costs, the feasible method at present is to adopt cooling rolling. Cooling rolling is to roll rebar below the recrystallization temperature, which avoids the growth of grains refined by rolling deformation, while reducing the amount of alloying elements, improving the elongation and strength of the material, and the rolling process will not produce closed martensite structure, thus meeting the requirements of the new national standard for steel performance and microstructure.

[0005] With advancements in steel rolling technology and the need for environmental cost control, cooled rolling technology has gained significant attention and application among steel companies. As rolling temperatures gradually decrease and rolling forces increase substantially, WC-Co-Ni-Cr cemented carbide roll rings struggle to meet the demands of high stress and high strength applications. This led to the development of WC-Co-Ni-Cr-Al roll ring materials. The addition of Al enhances the mechanical properties of cemented carbide materials under high-temperature conditions; however, elemental Al is highly reactive and prone to oxidation during manufacturing, resulting in porosity defects. In 1985, Japanese scholar Nishigaki proposed at the 11th Plancy International Conference to replace Al with AlN as an additive. During sintering, a γ' phase (Ni,Co)3Al is generated, giving the alloy excellent toughness, wear resistance, high-temperature strength, and oxidation resistance, theoretically solving this problem.

[0006] According to the research results in the papers "Research Progress on the Influence of γ' Phase on Strength, Fatigue and Creep Properties of Nickel-Based Superalloys" published by Zhu Jinqun et al., "Hardness Degradation and Anisotropic Characteristics of Nickel-Based Superalloys after Graining of Precipitated Phases" published by Zhang Shunyong et al., and "High-Temperature Alloys" published by Huang Qianyao et al., the microstructure of the γ' phase (Ni,Co)3Al tends to coarsen under long-term high-temperature and high-strength service, which leads to the deterioration of the high-temperature mechanical properties of the material.

[0007] Therefore, how to provide a novel binder cemented carbide to improve the thermal shock resistance of alloy materials is a technical problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0008] In view of this, the present invention discloses a Co-Ni-Cr-Al-Ti binder cemented carbide and its preparation method. This novel binder cemented carbide can effectively improve the thermal shock resistance of alloy materials and is suitable for promotion and application.

[0009] To achieve the above objectives, the present invention adopts the following technical solution: The first technical objective of this invention is a Co-Ni-Cr-Al-Ti binder cemented carbide, wherein the alloy composition is designed using a specific ratio of WC, Co, Ni, Cr, Al, and Ti components to prepare the cemented carbide material, wherein... The content of Co is 7.5-16%, the content of Ni is 7.5-16%, the content of Cr is 0.5-1.1%, the content of Al is 0.53-1.58%, the content of Ti is 0.01-0.03%, and the balance is WC.

[0010] Furthermore, the mass ratio of Co to Ni is 1:1, and Al and Ti are used as binder components, with their combined content accounting for 3 to 5% of the total content of Co, Ni, Al, and Ti.

[0011] The second technical objective of this invention is to provide a method for preparing the Co-Ni-Cr-Al-Ti binder cemented carbide as described above. The idea is to add Al in the form of AlN, using powder metallurgy to wet-mill and mix AlN powder with coarse WC powder (FSSSS particle size ≥ 20 μm), Co powder, Ni powder, Cr powder, and Ti powder. The AlN powder particle size is < 2 μm, and the Ti powder particle size is < 50 μm. The grinding media are hexane, a flux, and paraffin wax. The grinding media is a cemented carbide rod with a rod-to-material ratio of (3.0~2.0):1. After ball milling for 26~32 hours, the material is sequentially dried, sieved, granulated, pressed into a green compact, and then sintered and heat-treated. The high-temperature sintering temperature is 1380℃~1460℃, held for 1 hour. The heat treatment is 600℃~650℃, held for 20~30 hours, to improve the mechanical properties of the material. A novel binder cemented carbide was prepared by high-temperature sintering and heat treatment. The binder phase precipitates coherent strengthening phases (Ni,Co)3Al and (Co,Ni)3AlTi. This binder phase alloy has good thermal shock resistance under high temperature and high stress cyclic conditions, and has excellent high-temperature hardness and strength. The stability of the product under high temperature conditions is greatly improved.

[0012] Compared with the prior art, the beneficial effects of the present invention are: This invention addresses the key mechanism by which the precipitation of the γ' phase (Ni,Co)3Al in the Co-Ni-Cr-Al binder is a primary enhancement of the properties of WC-Co-Ni-Cr-Al cemented carbide. By adding a certain amount of Ti, a Co-Ni-Cr-Al-Ti binder is designed. The Ti dissolves into the γ' phase, effectively strengthening it through solid solution, thereby further improving the stability of the γ' phase structure under high-temperature conditions. This method preserves the inherent strengthening effect of the γ' phase while simultaneously strengthening it, ultimately enhancing the overall mechanical stability of the cemented carbide material. Detailed Implementation

[0013] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0014] The term "embodiment" used herein, as an example, is not necessarily to be construed as superior to or better than other embodiments. Performance testing in the embodiments of this application, unless otherwise specified, employs conventional testing methods in the art. It should be understood that the terminology used in this application is merely for describing particular implementations and is not intended to limit the scope of this disclosure.

[0015] Unless otherwise stated, the technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; other experimental methods and technical means not specifically mentioned herein refer to experimental methods and technical means commonly used by one of ordinary skill in the art.

[0016] To better illustrate the content of this application, numerous specific details are provided in the following detailed embodiments. Those skilled in the art should understand that this application can be implemented even without certain specific details. In the embodiments, some methods, means, instruments, and devices well-known to those skilled in the art are not described in detail in order to highlight the main points of this application.

[0017] Without conflict, the technical features disclosed in the embodiments of this application can be combined arbitrarily, and the resulting technical solution belongs to the content disclosed in the embodiments of this application.

[0018] This invention discloses a Co-Ni-Cr-Al-Ti binder cemented carbide with improved thermal shock resistance and its preparation method.

[0019] The alloy composition is designed to prepare cemented carbide materials using specific proportions of WC, Co, Ni, Cr, Al, and Ti. The Co:Ni mass ratio is 1:1, with Co content ranging from 7.5% to 16%, Ni content from 7.5% to 16%, Cr content from 0.5% to 1.1%, Al content from 0.53% to 1.58%, and the balance being WC. The total Al and Ti content accounts for 3% to 5% of the Co and Ni binder content, and the Ti content is 0.01% to 0.03%.

[0020] The present invention involves adding Al in the form of AlN. AlN powder is wet-milled and mixed with coarse WC powder (fsss particle size ≥ 20 μm), Co powder, Ni powder, Cr powder, and Ti powder using powder metallurgy. The AlN powder particle size is < 2 μm, and the Ti powder particle size is < 50 μm. The grinding media consists of hexane, a flux, and paraffin wax. The grinding media is a cemented carbide rod with a rod-to-material ratio of (3.0~2.0):1. After ball milling for 26~32 hours, the material is sequentially dried, sieved, granulated, pressed into a green compact, and then sintered and heat-treated. The high-temperature sintering temperature is 1380℃~1460℃, held for 1 hour. The heat treatment is carried out at 600℃~650℃ for 20~30 hours to improve the mechanical properties of the material. A novel binder cemented carbide was prepared by high-temperature sintering and heat treatment. The binder phase precipitates coherent strengthening phases (Ni,Co)3Al and (Co,Ni)3AlTi. This binder phase alloy has good thermal shock resistance under high temperature and high stress cyclic conditions, and has excellent high-temperature hardness and strength. The stability of the product under high temperature conditions is greatly improved.

[0021] To better understand the present invention, the following embodiments are provided for further detailed description of the present invention, but they should not be construed as limiting the present invention. Any non-essential improvements and adjustments made by those skilled in the art based on the above-described invention are also considered to fall within the protection scope of the present invention. Example 1:

[0022] 645.7g of WC powder (20.0μm Fisher particle size), 160.0g of Co powder, 160.0g of Ni powder, 10.0g of Cr powder, 24.0g of AlN powder, and 0.3g of Ti powder were mixed. For each kilogram of the mixed powder, 0.30L of hexane, 20g of paraffin wax, and 0.2g of co-solvent were added. The WC powder, Co powder, paraffin wax, and co-solvent were loaded into a ball mill at a ball-to-powder ratio of 3:1 and milled for 32 hours. After unloading, drying, granulation, and pressing, a compact was obtained and sintered at 1380℃ for 1 hour to obtain an alloy with a grain size of 2.43μm and a porosity of A02B00. After sintering, vacuum heat treatment was performed at 620℃ for 30 hours. Comparative Example 1:

[0023] 646.0 g of WC powder (20.0 μm Fisher's grain size), 160.0 g of Co powder, 160.0 g of Ni powder, 10.0 g of Cr powder, and 24.0 g of AlN powder were mixed. For each kilogram of the mixed powder, 0.30 L of hexane, 20 g of paraffin wax, and 0.2 g of co-solvent were added. The WC powder, Co powder, paraffin wax, and co-solvent were loaded into a ball mill at a ball-to-powder ratio of 3:1 and milled for 32 hours. After unloading, drying, granulation, and pressing, a compact was obtained and sintered at 1380℃ for 1 hour to obtain an alloy with a grain size of 2.49 μm and a porosity of A02B00. After sintering, vacuum heat treatment was performed at 620℃ for 30 hours.

[0024] Comparative Example 1 has a similar composition to Example 1, except that Ti is not added. Approximate thermal shock resistance tests were performed on Example 1 and Comparative Example 1. The samples were held at 650°C for 5h, 10h, 15h, and 20h, then rapidly cooled to room temperature under Ar gas at a cooling rate of 30°C / min. The alloy strength retention rate was measured after the samples were rapidly cooled following the initial holding period.

[0025] Strength retention rate = Alloy strength after heat treatment and rapid cooling ÷ Alloy room temperature strength * 100% The alloy properties of Example 1 and Comparative Example 1 are shown in Table 1. Table 1 Comparison of thermal shock resistance between alloys of Example 1 and Comparative Example 1 Example 2:

[0026] 733.8g of WC powder (20.0μm Fisher particle size), 120.0g of Co powder, 120.0g of Ni powder, 8.0g of Cr powder, 18.0g of AlN powder, and 0.2g of Ti powder were mixed. For each kilogram of the mixed powder, 0.30L of hexane, 20g of paraffin wax, and 0.2g of co-solvent were added. The WC powder, Co powder, paraffin wax, and co-solvent were loaded into a ball mill at a ball-to-powder ratio of 2.5:1 and milled for 28 hours. After unloading, drying, granulation, and pressing, a compact was obtained and sintered at 1410℃ for 1 hour to obtain an alloy with a grain size of 2.39μm and a porosity of A02B00. After sintering, vacuum heat treatment was performed at 650℃ for 20 hours. Comparative Example 2:

[0027] 734.0g of WC powder (20.0μm Fisher particle size), 120.0g of Co powder, 120.0g of Ni powder, 8.0g of Cr powder, and 18.0g of AlN powder were mixed. For each kilogram of the mixed powder, 0.30L of hexane, 20g of paraffin wax, and 0.2g of co-solvent were added. The WC powder, Co powder, paraffin wax, and co-solvent were loaded into a ball mill at a ball-to-powder ratio of 2.5:1 for 28 hours. After unloading, drying, granulation, and pressing, a compact was obtained and sintered at 1410℃ for 1 hour to obtain an alloy with a grain size of 2.42μm and a porosity of A02B00. After sintering, vacuum heat treatment was performed at 650℃ for 20 hours.

[0028] Comparative Example 2 has a similar composition to Example 2, except that Ti is not added. Approximate thermal shock resistance tests were performed on Example 2 and Comparative Example 2. The samples were held at 650°C for 5h, 10h, 15h, and 20h, then rapidly cooled to 30°C under Ar gas at a cooling rate of 30°C / min. The alloy strength retention rate was measured after the samples were held at 650°C and then rapidly cooled.

[0029] Table 2. Comparison of thermal shock resistance between alloys of Example 2 and Comparative Example 2.

[0030] Example 3:

[0031] 836.9 g of WC powder (20.0 μm Fisher's grain size), 75.0 g of Co powder, 75.0 g of Ni powder, 5.0 g of Cr powder, 8.0 g of AlN powder, and 0.1 g of Ti powder were mixed. For each kilogram of the mixed powder, 0.30 L of hexane, 20 g of paraffin wax, and 0.2 g of co-solvent were added. The WC powder, Co powder, paraffin wax, and co-solvent were loaded into a ball mill at a ball-to-powder ratio of 2:1 and milled for 26 hours. After unloading, drying, granulation, and pressing, a compact was obtained and sintered at 1460℃ for 1 hour to obtain an alloy with a grain size of 2.14 μm and a porosity of A02B00. After sintering, vacuum heat treatment was performed at 630℃ for 25 hours. Comparative Example 3:

[0032] 837.0g of WC powder (20.0μm Fisher particle size), 75.0g of Co powder, 75.0g of Ni powder, 5.0g of Cr powder, and 8.0g of AlN powder were mixed. For each kilogram of the mixed powder, 0.30L of hexane, 20g of paraffin wax, and 0.2g of co-solvent were added. The WC powder, Co powder, paraffin wax, and co-solvent were loaded into a ball mill at a ball-to-powder ratio of 2.0:1 for 26 hours. After unloading, drying, granulation, and pressing, a compact weighing 42.0kg was obtained. The compact was sintered at 1460℃ for 1 hour to obtain an alloy with a grain size of 2.18μm and a porosity of A02B00. After sintering, vacuum heat treatment was performed at 630℃ for 25 hours.

[0033] Comparative Example 3 has a composition similar to Example 3, except that Ti is not added. Approximate thermal shock resistance tests were performed on Example 3 and Comparative Example 3. The samples were held at 650°C for 5h, 10h, 15h, and 20h, then rapidly cooled to 30°C under Ar gas at a cooling rate of 30°C / min. The alloy strength retention rate was measured after the samples were held at 650°C and then rapidly cooled.

[0034] Table 3 Comparison of thermal shock resistance between alloys of Example 3 and Comparative Example 3

[0035] By comparing the thermal shock performance of the embodiments and comparative examples, it was found that after the implementation of the present invention, the stability of the high-temperature mechanical properties of WC-Co-Ni-Cr-Al-Ti materials is improved, especially the improvement in alloy strength stability is the most obvious. This feature may provide a favorable solution for cemented carbide materials to serve under high temperature and high load conditions.

[0036] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A Co-Ni-Cr-Al-Ti binder cemented carbide, characterized in that, Hard alloy materials are prepared using a specific ratio of WC, Co, Ni, Cr, Al, and Ti components, wherein... The content of Co is 7.5-16%, the content of Ni is 7.5-16%, the content of Cr is 0.5-1.1%, the content of Al is 0.53-1.58%, the content of Ti is 0.01-0.03%, and the balance is WC.

2. The Co-Ni-Cr-Al-Ti binder cemented carbide according to claim 1, characterized in that, The mass ratio of Co to Ni is 1:

1. Al and Ti are used as binder components, and their combined content accounts for 3 to 5% of the total content of Co, Ni, Al and Ti.

3. A method for preparing a Co-Ni-Cr-Al-Ti binder cemented carbide as described in claim 1 or 2, characterized in that, The preparation method involves the following steps: A novel binder cemented carbide was prepared by wet milling AlN powder with coarse WC powder, Co powder, Ni powder, Cr powder and Ti powder using powder metallurgy. After ball milling, the mixture was dried, sieved, granulated, pressed into a green blank, and then sintered and heat-treated.

4. The preparation method of Co-Ni-Cr-Al-Ti binder cemented carbide according to claim 3, characterized in that, WC powder with a Fisher particle size ≥ 20 μm, AlN powder with a particle size < 2 μm, and Ti powder with a particle size < 50 μm. The grinding media consists of hexane, a co-solvent, and paraffin. The grinding media is cemented carbide rods with a rod-to-material ratio of (3.0~2.0):

1. The ball milling time is 26h~32h.

5. The method for preparing Co-Ni-Cr-Al-Ti binder cemented carbide according to claim 3, characterized in that, The high-temperature sintering temperature is 1380℃~1460℃, and the holding time is 1 hour.

6. The method for preparing Co-Ni-Cr-Al-Ti binder cemented carbide according to claim 3, characterized in that, The heat treatment temperature is 600℃~650℃, and the holding time is 20h~30h.

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