Fine-grained cubic phase uniformly distributed cemented carbide and method for producing the same

Abstract

This invention discloses a cemented carbide with a uniformly distributed fine-grained cubic phase and its preparation method. The cemented carbide comprises a WC hard phase, a (Ti,X,W)C cubic phase, and a binder phase. The binder phase is a Co binder phase or a binder phase composed of Co and Cr. X is at least one element selected from Ta, Nb, Zr, and V. The average grain size G of the (Ti,X,W)C cubic phase is... S ≤0.90μm, and the ratio S of the cross-sectional area of ​​the cubic phase to its grain number. N ≤0.80μm 2 The mass fraction M of element W in the cubic phase W ≥60%. The preparation method includes mixture preparation and alloy preparation. The cubic phase grains in the cemented carbide of this invention are fine and uniformly distributed, exhibiting high red hardness and wear resistance. The preparation method is simple and easy to implement.

Description

Technical Field

[0001] This invention relates to the field of cemented carbide technology, specifically to a cemented carbide with a uniformly distributed fine-grained cubic phase and its preparation method. Background Technology

[0002] Carbide inserts and coated inserts based on carbide are widely used in metal cutting. With the continuous improvement of machining efficiency, carbide is required to withstand higher temperatures during service, making its high-temperature performance a key factor affecting the service life of cutting inserts. Therefore, developing carbide materials with high red hardness has become an important development direction for cutting inserts.

[0003] Currently, adding a certain amount of solid solution powder raw materials, such as (Ti,W)C, (Ta,Nb)C, and (Ti,Ta / Nb,W)C, has become an effective means to improve the high-temperature hardness and resistance to crater wear of cemented carbides. However, these solid solution powders undergo significant growth and aggregation during the sintering stage of cemented carbide preparation, resulting in cubic phase coarsening and poor microstructure uniformity. Cubic phase coarsening leads to a reduction in the number of cubic phase particles per unit area, thus decreasing the effect of cubic phase on improving high-temperature hardness; cubic phase aggregation creates large brittle regions in the microstructure, increasing the fracture sources of the alloy. Both of these phenomena significantly reduce the performance of cemented carbides. Therefore, the refinement and homogenization of the cubic phase are key points for improving the high-temperature hardness of the alloy and ensuring its performance.

[0004] CN113462919A discloses a method for preparing a hard alloy with cubic phase particles of no more than 1 μm dispersed in a WC+Co matrix using saturated solid solution (Ti,W,Ta,Nb)C. However, its preparation process is complex and requires a Co mass fraction of 6.5%, limiting its application scope.

[0005] EP1526189A1 discloses a cemented carbide with an average particle size of less than 1 μm for both the cubic phase and WC by using a complex carbide (Me, W)C raw material powder and controlling its carbide composition. Me is a combination of one or more metallic elements selected from Ti, Ta, Nb, Zr, Hf, and V. However, this patent document requires that the complex carbide (Me, W)C raw material powder used must be less than 1 μm and the WC raw material powder must be at the submicron level, significantly increasing the raw material cost. Furthermore, the resulting cemented carbide with an average WC particle size of less than 1 μm inevitably reduces the alloy's toughness. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to overcome the shortcomings of the prior art and provide a cemented carbide with a uniform distribution of fine cubic phase and its preparation method, so as to further reduce the average grain size of cubic phase in cemented carbide and improve its distribution uniformity without increasing the cost of raw materials, thereby improving the red hardness of the alloy to adapt to the high-temperature service environment during the cutting process.

[0007] To solve the above-mentioned technical problems, the present invention adopts the following technical solution.

[0008] A fine-grained cubic phase uniformly distributed in a cemented carbide comprises a WC hard phase, a (Ti,X,W)C cubic phase, and a binder phase. The binder phase is a Co binder phase or a binder phase composed of Co and Cr. In the (Ti,X,W)C cubic phase, X is at least one element selected from Ta, Nb, Zr, and V. The average grain size G of the (Ti,X,W)C cubic phase is... S ≤0.90μm, the ratio S of the cross-sectional area of ​​the (Ti,X,W)C cubic phase to its grain number. N ≤0.80μm 2 .

[0009] In the aforementioned cemented carbide with a uniformly distributed fine-grained cubic phase, preferably, the mass fraction M of the W element in the (Ti,X,W)C cubic phase is... W ≥60%.

[0010] Preferably, in the above-mentioned cemented carbide with uniformly distributed fine-grained cubic phase, the mass fraction of Co is 5% to 13%, the mass fraction of Cr is 0% to 0.5%, the mass fraction of Ti is 0.5% to 4.0%, the sum of the mass fractions of Ta and Nb is 0% to 6%, the mass fraction of V is 0% to 0.5%, and the mass fraction of Zr is 0% to 0.5%.

[0011] More preferably, in the aforementioned cemented carbide with uniformly distributed fine-grained cubic phase, the mass fraction of Co is 5% to 11%, the mass fraction of Cr is 0% to 0.5%, the mass fraction of Ti is 1.5% to 3.5%, the sum of the mass fractions of Ta and Nb is 0% to 3.8%, the mass fraction of V is 0% to 0.5%, and the mass fraction of Zr is 0% to 0.5%.

[0012] As a general technical concept, the present invention also provides a method for preparing the above-mentioned fine-grained cubic phase uniformly distributed cemented carbide, comprising the following steps:

[0013] (1) Preparation of the mixture: Prepare TiC powder and (Ti) powder according to the mass fraction of cemented carbide elements. 1-y W yWC powder raw material is mixed and wet ball milled, wherein 0.35≤y≤0.42; then WC powder, Co powder and Ti(C,N) powder are added for the second feeding, and ball milling is continued. After ball milling is completed, the resulting slurry is dried and granulated to obtain a mixture.

[0014] (2) Alloy preparation: The above-obtained mixture is molded or isostatically pressed, and then heated to 1410℃~1480℃ and held at that temperature. After heating to 1350℃, 20mbar~100mbar of argon gas is introduced. After the holding period, the mixture is cooled to obtain a hard alloy with a uniformly distributed fine cubic phase.

[0015] In the above-mentioned method for preparing a fine-grained cubic phase uniformly distributed cemented carbide, preferably, the Fisher particle size of the TiC powder is 1.1 μm to 1.5 μm, and the (Ti) 1-y W y The Fehling particle size of the C powder is 0.8 μm to 1.5 μm, and the Fehling particle size of the WC powder is 2.5 μm to 4.0 μm.

[0016] The above-mentioned method for preparing a cemented carbide with a uniformly distributed fine-grained cubic phase, preferably, involves the following: 1-y W y The Fisher particle size of the C powder is 1.2μm to 1.5μm.

[0017] In the above-mentioned method for preparing a cemented carbide with a uniformly distributed fine-grained cubic phase, preferably, in step (1), the mass of the TiC powder accounts for 0.5% to 1.0% of the total mass of the raw materials, and the (TiC powder accounts for 0.5% to 1.0% of the total mass of the raw materials.) 1-y W y The mass of C powder accounts for 2.5% to 10.5% of the total mass of the raw materials.

[0018] In the above-mentioned method for preparing a cemented carbide with a uniformly distributed fine-grained cubic phase, preferably, in step (2), the heat preservation time is 1h to 2h.

[0019] In the above-mentioned method for preparing cemented carbide with uniformly distributed fine cubic phase, preferably, in step (1), the wet ball milling time is 10h to 40h, and the ball milling time after the second feeding is 15h to 30h.

[0020] In the preferred method for preparing the above-mentioned fine-grained cubic phase uniformly distributed cemented carbide, in step (1), during the second feeding, (Ta) is also added. 1-z ,Nb z One or more of C powder, NbC powder, Cr3C2 powder, VC powder and ZrC powder, wherein 0≤z≤0.55.

[0021] The production of cemented carbide involves adjusting the proportions of raw materials to achieve predetermined elemental requirements. This means adjusting the proportions of each raw material according to a set of defined elemental standards, ensuring that the proportions meet the elemental requirements.

[0022] Compared with the prior art, the advantages of the present invention are as follows:

[0023] (1) In existing cemented carbides, the average grain size of the cubic phase is generally above 1 μm. In the cemented carbides of this invention with uniformly distributed fine-grained cubic phase, the average grain size of the (Ti,X,W)C cubic phase is G. S ≤0.90μm. Cubic phase refinement can further improve the red hardness and wear resistance of cemented carbide, increasing its machining efficiency or service life when used as a cutting tool.

[0024] (2) In existing cemented carbides, the mass fraction of W in the cubic phase is 45-55%. In the cemented carbides of this invention with uniformly distributed fine-grained cubic phase, the mass fraction of W in the (Ti,X,W)C cubic phase is M. W ≥60%. In cemented carbide with the same Ti content, a high W content in the (Ti,X,W)C cubic phase will increase the volume percentage of the cubic phase. The increase in cubic phase can improve the red hardness and wear resistance of cemented carbide, and increase its machining efficiency or service life when used as a cutting tool.

[0025] (3) In this invention, the solid solution powder is first ball-milled, and then WC is added and ball-milled, that is, TiC and (Ti) are added. 1-y W y The ball milling time of WC powder ensures the refinement of the raw materials for forming the cubic phase. If the ball milling time is increased for all powder raw materials, including WC powder, the resulting cemented carbide will have an excessively fine WC phase particle size, which will reduce the strength and toughness of the cemented carbide.

[0026] In existing technologies, during sintering, a large amount of W element dissolves into the cubic phase, leading to the growth of the final (Ti,X,W)C cubic phase. This invention improves the (Ti)C cubic phase... 1-y W y The W content in the C powder raw material reduces the amount of W element dissolved into the cubic phase during sintering, thus reducing the growth of the cubic phase during sintering.

[0027] This invention reduces the accumulation of cubic phases during sintering by adding TiC powder.

[0028] This invention reduces the amount of liquefied binder phase by introducing argon gas during sintering, thereby further reducing the growth efficiency of the cubic phase.

[0029] The cemented carbide preparation method of the present invention is simple and easy to implement. Attached Figure Description

[0030] Figure 1 This is a photograph of the microstructure of a cemented carbide with a uniform distribution of fine-grained cubic phases according to Example 1 of the present invention. The labels in the figure represent: 1. WC hard phase; 2. (Ti,Ta,Nb,W,Zr)C cubic phase; 3. binder phase.

[0031] Figure 2 The image shows the microstructure of the cemented carbide in Comparative Example 1. The labels in the image represent: 1. WC hard phase; 2. (Ti,Ta,Nb,W,Zr)C cubic phase; 3. binder phase.

[0032] Figure 3 This is a photograph of the microstructure of a cemented carbide with a uniform distribution of fine-grained cubic phases, as shown in Example 2 of this invention. The labels in the figure represent: 1. WC hard phase; 2. (Ti,Ta,Nb,W,Zr)C cubic phase; 3. binder phase.

[0033] Figure 4 The image shows the microstructure of the cemented carbide in Comparative Example 2. The labels in the image represent: 1. WC hard phase; 2. (Ti,Ta,Nb,W,Zr)C cubic phase; 3. binder phase; 4. (Ti,Ta,Nb,W,Zr)C cubic phase aggregation region.

[0034] Figure 5 This is a photograph of the microstructure of a cemented carbide with a uniform distribution of fine-grained cubic phases in Example 3 of the present invention. The labels in the figure represent: 1. WC hard phase; 2. (Ti,Ta,Nb,W,Zr)C cubic phase; 3. binder phase.

[0035] Figure 6 The image shows the microstructure of the cemented carbide in Comparative Example 3. The labels in the image represent: 1. WC hard phase; 2. (Ti,Ta,Nb,W,Zr)C cubic phase; 3. binder phase. Detailed Implementation

[0036] The present invention will be further described below with reference to the accompanying drawings and specific preferred embodiments, but this does not limit the scope of protection of the present invention. All materials and instruments used in the following embodiments are commercially available.

[0037] Example 1

[0038] A fine-grained cubic phase uniformly distributed cemented carbide of the present invention comprises a WC hard phase, a (Ti,Ta,Nb,W,Zr)C cubic phase, and a binder phase composed of Co and Cr. The average grain size G of the (Ti,Ta,Nb,W,Zr)C cubic phase is... S The cross-sectional area of ​​this cubic phase is 0.81 μm, and the ratio S of its cross-sectional area to the number of grains is... N 0.57μm 2The mass fraction M of element W in this cubic phase W = 61.2%. The mass fraction of Co in this cemented carbide is 7.5%, Ti is 1.9%, Ta is 1.5%, Nb is 1.0%, Cr is 0.15%, and Zr is 0.05%.

[0039] A method for preparing a fine-grained cubic phase uniformly distributed cemented carbide according to this embodiment includes the following steps:

[0040] (1) Preparation of mixture

[0041] The mass fraction (as a percentage of the total mass of the raw materials in step (1)) is 0.76% TiC and 2.9% (Ti 0.59 W 0.41 C, 2.1% (Ta 0.45 ,Nb 0.55 TiC powder and 0.63% NbC powder were mixed and wet ball-milled for 20 hours. The Fisher particle size of the TiC powder was 1.1 μm. 0.59 W 0.41 The WC powder had a Fisher particle size of 1.4 μm. Then, 85.11% WC, 7.5% Co, 0.77% Ti(C,N), 0.17% Cr3C2, and 0.06% ZrC powder were added by mass, and ball milling continued for 25 hours. The WC powder had a Fisher particle size of 2.9 μm. After ball milling, the resulting slurry was dried and granulated to obtain a mixture.

[0042] (2) Alloy preparation

[0043] The mixture prepared above was molded, then heated to 1350℃ and filled with 20 mbar argon gas. The temperature was then further increased to 1470℃ and held for 1 hour before cooling to obtain a cemented carbide with a uniformly distributed fine-grained cubic phase. Figure 1 As shown.

[0044] Comparative Example 1

[0045] All raw material powders were ball-milled together for 25 hours at the same mass fraction as in Example 1. The remaining preparation methods were the same as in Example 1, and the following results were obtained: Figure 2 The cemented carbide shown has a significantly coarser cubic phase than the sample in Example 1, with an average grain size of 1.2 μm. The high-temperature Vickers hardness of the samples from Comparative Example 1 and Example 1 was tested at 800 °C, and the results are shown in Table 1 below.

[0046] Table 1. High-temperature Vickers hardness (800℃) of samples from Example 1 and Comparative Example 1

[0047] sample Hv(MPa) Embodiment 1 of the present invention 800 Comparative Example 1 714

[0048] Depend on Figure 1 , Figure 2 As can be seen from Table 1, under the same raw materials and composition, the solution of the present invention refines the cubic phase of the alloy and results in higher high-temperature hardness of the alloy.

[0049] Example 2

[0050] A fine-grained cubic phase uniformly distributed cemented carbide of the present invention comprises a WC hard phase, a (Ti,Ta,Nb,W,Zr)C cubic phase, and a binder phase composed of Co and Cr. The average grain size G of the (Ti,Ta,Nb,W,Zr)C cubic phase is... S The cross-sectional area of ​​this cubic phase is 0.90 μm, and the ratio S of its grain size to the number of grains is... N 0.78μm 2 The mass fraction M of element W in this cubic phase W =63%. In this cemented carbide, the mass fraction of Co is 10%, the mass fraction of Cr is 0.15%, the mass fraction of Ti is 2.9%, the mass fraction of Ta is 1.2%, the mass fraction of Nb is 0.5%, and the mass fraction of Zr is 0.05%.

[0051] A method for preparing a fine-grained cubic phase uniformly distributed cemented carbide according to this embodiment includes the following steps:

[0052] (1) Preparation of mixture

[0053] 0.76% TiC powder and 7.06% (Ti) by mass were used. 0.58 W 0.42 C, 1.68% (Ta 0.45 ,Nb 0.55 TiC powder and 0.16% NbC powder were mixed and wet ball-milled for 22 hours. The Fisher particle size of the TiC powder was 1.1 μm. 0.58 W 0.42 The Fehling particle size of the WC powder was 1.45 μm. Then, 79.34% WC, 10% Co, 0.77% Ti(C,N), 0.17% Cr3C2, and 0.06% ZrC powder were added by mass, and ball milling continued for 20 hours. The Fehling particle size of the WC powder was 3.5 μm. After ball milling, the resulting slurry was dried and granulated to obtain a mixture.

[0054] (2) Blank preparation

[0055] The mixture prepared above was molded, then heated to 1350℃ and filled with 40 mbar argon gas. The temperature was then further increased to 1450℃ and held for 1 hour before cooling to obtain a cemented carbide with a uniformly distributed fine-grained cubic phase. Figure 3 As shown.

[0056] Comparative Example 2

[0057] Without adding TiC powder, the rest of the preparation process is the same as in Example 2, yielding the following result: Figure 4 The cemented carbide shown.

[0058] Depend on Figure 3 , Figure 4 It can be seen that the present invention effectively reduces the aggregation phenomenon during the cubic phase growth process by adding TiC powder, while the comparative sample 2 without TiC powder showed severe cubic phase aggregation.

[0059] Example 3

[0060] A fine-grained cubic phase uniformly distributed cemented carbide of the present invention comprises a WC hard phase, a (Ti,Ta,Nb,W,Zr)C cubic phase, and a binder phase composed of Co and Cr. The average grain size G of the (Ti,Ta,Nb,W,Zr)C cubic phase is... S The cross-sectional area of ​​this cubic phase is 0.85 μm, and the ratio S of its grain size to the number of grains is... N 0.69μm 2 The mass fraction M of element W in this cubic phase W =61.8%. In this cemented carbide, the mass fraction of Co is 10%, the mass fraction of Cr is 0.1%, the mass fraction of Ti is 2.5%, the mass fraction of Ta is 2.2%, the mass fraction of Nb is 0.7%, and the mass fraction of Zr is 0.05%.

[0061] A method for preparing a fine-grained cubic phase uniformly distributed cemented carbide according to this embodiment includes the following steps:

[0062] (1) Preparation of mixture

[0063] 0.54% TiC powder and 6.38% (Ti) were mixed. 0.58 W 0.42 C, 3.08% (Ta 0.45 ,Nb 0.55 TiC powder with 0.06% NbC was wet-ball-milled for 25 hours, wherein the Fisher particle size of the TiC powder was 1.3 μm. 0.58 W 0.42 The WC powder had a Fisher particle size of 1.45 μm. Then, 79.07% WC powder, 10% Co powder, 0.69% Ti(C,N) powder, 0.12% Cr3C2 powder, and 0.06% ZrC powder were added by mass, and ball milling continued for 23 hours. The WC powder had a Fisher particle size of 3.2 μm. After ball milling, the resulting slurry was dried and granulated to obtain a mixture.

[0064] (2) Blank preparation

[0065] The mixture prepared above was molded into the desired shape, then heated to 1350℃ and filled with 60 mbar argon gas. The temperature was then further increased to 1460℃ and held for 1 hour before cooling to obtain a cemented carbide with a uniformly distributed fine-grained cubic phase. Figure 5 As shown.

[0066] Comparative Example 3

[0067] The Ti used 1-y W y The C powder has a y = 0.29 and a Fisher particle size of 1.8 μm. The remaining preparation process is the same as in Example 3, yielding the following result. Figure 6 The cemented carbide shown exhibits a significantly coarser and larger cubic phase compared to the sample in Example 3, with an average grain size of 1.3 μm. The high-temperature Vickers hardness of the samples from Comparative Example 3 and Example 3 was tested at 800 °C, and the results are shown in Table 2 below.

[0068] Table 2. High-temperature Vickers hardness (800℃) of samples from Example 3 and Comparative Example 3.

[0069] sample Hv(MPa) Embodiment 1 of the present invention 632 Comparative Example 3 579

[0070] Depend on Figure 5 , Figure 6 As shown in Table 2, the present invention improves (Ti,W) y The W content in C reduces the extent to which W grows through dissolution during sintering, resulting in a finer cubic phase in the sintered alloy and higher high-temperature hardness.

[0071] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make many possible variations and modifications to the technical solutions of the present invention using the methods and techniques disclosed above, or modify them into equivalent embodiments with equivalent changes, without departing from the spirit and technical essence of the present invention. Therefore, any simple modifications, equivalent substitutions, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solutions of the present invention shall still fall within the protection scope of the technical solutions of the present invention.

Claims

1. A method of producing a cemented carbide with a fine-grained cubic phase uniformly distributed, characterized in that, The method comprises the following steps: (1) mixture preparation: according to the mass fraction of cemented carbide elements, prepare TiC powder, (Ti 1-y , W y )C powder raw materials, mix and wet ball mill, wherein 0.35≤y≤0.42; then second feeding, add WC powder, Co powder, Ti(C, N) powder, also add one or more of (Ta 1-z , Nb z )C powder, NbC powder, Cr3C2 powder, VC powder and ZrC powder, wherein 0≤z≤0.55, continue ball milling, after ball milling is completed, dry the obtained slurry, granulate to obtain the mixture; (2) alloy preparation: the mixture obtained in the above step is subjected to die molding or isostatic pressing, then heated to 1410-1480 DEG C and kept for a period of time, wherein argon is filled in at 20-100 mbar after the temperature is raised to 1350 DEG C, and then cooled after the keeping is finished, thereby obtaining a fine-grained cubic phase hard alloy with uniform distribution; The cemented carbide in which fine cubic phases are uniformly distributed includes a WC hard phase, a (Ti, X, W)C cubic phase, and a binder phase, the binder phase being a Co binder phase or a binder phase composed of Co and Cr, in the (Ti, X, W)C cubic phase, X is at least one element among Ta, Nb, Zr, and V, the average grain size G of the (Ti, X, W)C cubic phase S ≤ 0.90 μm, the ratio S of the cross-sectional area of the (Ti, X, W)C cubic phase to the number of grains thereof N ≤ 0.80 μm 2 .

2. The production method of fine-grained cubic phase uniformly distributed cemented carbide according to claim 1, characterized in that, The Feuer particle size of the TiC powder is 1.1 μm to 1.5 μm, the Feuer particle size of the (Ti 1-y , W y )C powder is 0.8 μm to 1.5 μm, and the Feuer particle size of the WC powder is 2.5 μm to 4.0 μm.

3. The production method of fine-grained cubic phase uniformly distributed cemented carbide according to claim 2, characterized in that, The (Ti 1-y , W y )C powder has a Fisher particle size of 1.2 μm to 1.5 μm.

4. The production method of fine-grained cubic phase uniformly distributed cemented carbide according to claim 1, characterized in that, In step (1), the mass of the TiC powder is 0.5% to 1.0% of the total mass of the raw materials, and the mass of the (Ti 1-y , W y )C powder is 2.5% to 10.5% of the total mass of the raw materials.

5. The method of producing a cemented carbide with a uniform distribution of fine cubic phase according to any one of claims 1 to 4, characterized in that, In step (2), the keeping time is 1-2 hours.

6. The method of producing a cemented carbide with a uniform distribution of fine cubic phase according to any one of claims 1 to 4, characterized in that, In step (1), the wet ball milling time is 10-40 hours, and the ball milling time after the second feeding is 15-30 hours.

7. The method of producing a cemented carbide with a uniform distribution of fine cubic phase according to any one of claims 1 to 4, characterized in that, the mass fraction M of the W element in the (Ti, X, W)C cubic phase W ≥ 60%.

8. The method of producing a cemented carbide with a uniform distribution of fine cubic phase according to any one of claims 1 to 4, characterized in that, In the hard alloy, the mass fraction of Co is 5-13%, the mass fraction of Cr is 0-0.5%, the mass fraction of Ti is 0.5-4.0%, the mass fraction of Ta and Nb is 0-6%, the mass fraction of V is 0-0.5%, and the mass fraction of Zr is 0-0.5%.

9. The method of producing a cemented carbide with a uniform distribution of fine cubic phase according to any one of claims 1 to 4, characterized in that, In the hard alloy, the mass fraction of Co is 5-11%, the mass fraction of Cr is 0-0.5%, the mass fraction of Ti is 1.5-3.5%, the mass fraction of Ta and Nb is 0-3.8%, the mass fraction of V is 0-0.5%, and the mass fraction of Zr is 0-0.5%.

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