Production process of non-uniform hard alloy

Abstract

The invention discloses a non-uniform hard alloy production process, and relates to the technical field of hard alloy production, the non-uniform hard alloy production process comprises the following steps: S1, mixing WC, a binding phase and an inhibitor to obtain mixed powder, sequentially adding a forming agent, a grinding body and a ball milling medium into the mixed powder, and starting a ball mill for mixing to obtain a mixed material; wherein the WC comprises WC1, WC2 and WC3, the Fisher particle size of the WC1 is 0.6-0.8 [mu] m, the Fisher particle size of the WC2 is 1.0-2.0 [mu] m, the Fisher particle size of the WC3 is 3.0-5.0 [mu] m, and the mass ratio of the WC1 to the WC2 to the WC3 is (6-8): (0.5-1.5): (1-3); s2, sequentially drying and granulating the mixed material, and then carrying out pressure forming to obtain a pressed blank; s3, the pressed blank is dewaxed and sintered, and the non-uniform hard alloy is obtained; through the three WC particles with different Fisher particle sizes, the fracture toughness is improved under the condition that the wear resistance is not reduced, meanwhile, the high bending strength is achieved, and the general machining life of the hard alloy bar can be greatly prolonged.

Description

Technical Field

[0001] This invention relates to the field of cemented carbide production technology, and specifically to a production process for non-uniform cemented carbide. Background Technology

[0002] Currently, cemented carbide rods are made from submicron or even ultrafine-grained tungsten carbide, resulting in limited versatility. It's difficult to achieve both high hardness and high toughness simultaneously in cemented carbide. Research on crack propagation within non-uniform cemented carbide mixtures of various WC grain sizes reveals that fracture is no longer limited to intergranular or transgranular processes. Due to the presence of coarse-grained WC, when crack propagation encounters these grains, it either bypasses them or penetrates them. Regardless of the method, more work is required. Therefore, non-uniform cemented carbide with appropriate mixing ratios can achieve better strength, toughness, and bending strength while maintaining good hardness.

[0003] To resolve the contradiction between hardness and toughness in cemented carbide, the industry currently employs two main methods: one is the preparation of coated cemented carbide. However, the preparation of coated cemented carbide requires advanced technology and significant equipment investment, resulting in high production costs. The other method is the preparation of gradient structure cemented carbide. However, the preparation of gradient structure cemented carbide involves complex processes and high production costs. Liu Chao et al. (Preparation and Performance Study of Mixed-Crystal WC-8Co Cemented Carbide, Central South University, 2014) reported that by combining WC powders of different particle sizes, a mixed-crystal structure cemented carbide with a bimodal distribution of hard phase particle size can be prepared. This material combines the performance advantages of both coarse and fine cemented carbides and exhibits consistent internal and external properties. However, due to the significant difference in solubility of coarse and fine WC powders in the binder phase Co, most of the fine WC particles preferentially dissolve during liquid-phase sintering and precipitate on the surface of larger particles. This leads to the easy agglomeration and growth of coarse WC particles, making it difficult to obtain a uniform microstructure in the material prepared by this method. The hard phase size distribution may even deviate from the original design requirements, so it has not yet been successfully used in industrial production. Summary of the Invention

[0004] The purpose of this invention is to at least solve one of the technical problems existing in the prior art and to provide a production process for non-uniform cemented carbide.

[0005] The technical solution of the present invention is as follows:

[0006] A manufacturing process for a non-uniform cemented carbide includes the following steps:

[0007] S1: Mix WC, binder phase and inhibitor to obtain mixed powder, add forming agent, grinding media and ball milling media to mixed powder in sequence, turn on ball mill to mix materials to obtain mixed material;

[0008] WC includes WC1, WC2 and WC3. The Fisher particle size of WC1 is 0.6-0.8 μm, the Fisher particle size of WC2 is 1.0-2.0 μm, and the Fisher particle size of WC3 is 3.0-5.0 μm. By mass ratio, WC1:WC2:WC3 = 6-8:0.5-1.5:1-3.

[0009] S2: The mixture is dried and granulated in sequence, and then pressed into shape to obtain a pressed blank;

[0010] S3: Dewaxing and sintering the pressed blank to obtain a non-uniform hard alloy.

[0011] As a preferred embodiment of the present invention, in step S1, the binder phase is Co or a mixture of Co and Ni;

[0012] The WC content of the mixed powder is 85-95% by mass, the binder content of the mixed powder is 5-15% by mass, and the remainder is an inhibitor.

[0013] The inhibitor comprises TaC and Cr3C2 in a mass ratio of 1:0.2-0.4;

[0014] Mixed powder: forming agent: grinding media: ball milling media = 1:(0.02-0.03):(4-5):(350-400).

[0015] As a preferred embodiment of the present invention, in step S2, the pressure of the pressure molding is 500-1000MPa.

[0016] As a preferred embodiment of the present invention, in step S3, during dewaxing, the vacuum degree in the vacuum furnace is 10-15 Pa, and the carrier gas flow rate is 1.5-3.5 m³ / s. 3 / h, temperature is 350-600℃, and the heat preservation time is 2-4h.

[0017] As a preferred embodiment of the present invention, in step S3, during sintering, the vacuum degree in the vacuum furnace is 0.01-0.05 Pa, the temperature is 1400-1420℃, and the holding time is 1-1.5 h.

[0018] The present invention also discloses a non-uniform cemented carbide, which is prepared by any of the above-described production processes.

[0019] As a preferred embodiment of the present invention, the hardness is greater than 1600HV3, the tensile strength is greater than 3500MPa, and the fracture toughness is greater than 11.5MPa·m. 1 / 2 .

[0020] The beneficial effects of this invention are as follows: This invention addresses the issue that the general processing life of current cemented carbide rod grades cannot meet various processing conditions. It designs and invents a method for preparing non-uniform cemented carbide, which improves fracture toughness without reducing wear resistance by using WC particles of three different zeolite particle sizes. At the same time, it also has high bending strength, which can greatly improve the general processing life of cemented carbide rods. Whether it is finishing or roughing, it can have a better processing life, greatly enhancing product competitiveness. Attached Figure Description

[0021] Figure 1 The images shown are microscopic images of Example 1, (a) is a metallographic image, and (b) is a scanning electron microscope image.

[0022] Figure 2 The images shown are microscopic images of Comparative Example 1, (a) is a metallographic image, and (b) is a scanning electron microscope image.

[0023] Figure 3 The following are the cutting edge wear diagrams for the cutting test tools: (a) is Example 1, (b) is Comparative Example 1, (c) is Comparative Example 2, (d) is Comparative Example 3, and (e) is Comparative Example 4. Detailed Implementation

[0024] The embodiments of the present invention are described in detail below. These embodiments are exemplary and are only used to explain the present invention, and should not be construed as limiting the invention. Where specific techniques or conditions are not specified in the embodiments, they are performed according to the techniques or conditions described in the literature in the art or according to the product instructions. Reagents or instruments used, unless otherwise specified, are all commercially available conventional products.

[0025] Example 1

[0026] S1: Mix WC, binder phase (Co) and inhibitor to obtain mixed powder. Add molding agent (paraffin), grinding media (grinding balls) and ball milling media (370ml / kg alcohol) to the mixed powder in sequence. Turn on the ball mill to ball mill and mix for 14.5 hours to obtain the mixed material.

[0027] WC includes WC1, WC2 and WC3. The Fisher particle size of WC1 is 0.6 μm, the Fisher particle size of WC2 is 1.0 μm and the Fisher particle size of WC3 is 3.0 μm. By mass ratio, WC1:WC2:WC3 = 7:1:2.

[0028] S2: The mixture is dried and granulated in sequence, and then pressed into shape to obtain a pressed blank;

[0029] S3: Dewaxing and sintering the pressed blank to obtain a non-uniform hard alloy.

[0030] In step S1, WC accounts for 89.5% of the mass fraction of the mixed powder, the binder phase accounts for 10% of the mass fraction of the mixed powder, and the remainder is an inhibitor (0.5%).

[0031] The inhibitor comprises TaC and Cr3C2 in a mass ratio of 1:0.3;

[0032] Mixed powder: forming agent: grinding media: ball milling media = 1:0.02:4:350.

[0033] In step S2, the pressure for the pressurization molding is 800 MPa.

[0034] In step S3, during dewaxing, the vacuum level in the vacuum furnace is 12 Pa, and the carrier gas flow rate is 3 m³ / s. 3 / h, temperature is 450℃, and the heat preservation time is 3h.

[0035] In step S3, during sintering, the vacuum degree in the vacuum furnace is 0.03 Pa, the temperature is 1410℃, and the holding time is 1 h.

[0036] Example 2

[0037] Unlike Example 1, WC includes WC1, WC2 and WC3, with WC1 having a Fisher particle size of 0.7 μm, WC2 having a Fisher particle size of 1.5 μm and WC3 having a Fisher particle size of 4.0 μm. The mass ratio of WC1:WC2:WC3 is 6:1:3.

[0038] Example 3

[0039] Unlike Example 1, WC includes WC1, WC2 and WC3, with WC1 having a Fisher particle size of 0.8 μm, WC2 having a Fisher particle size of 1.5 μm and WC3 having a Fisher particle size of 5.0 μm. The mass ratio of WC1:WC2:WC3 is 8:1:3.

[0040] Comparative Example 1 (only one particle size range)

[0041] Unlike Example 1, the Fisher particle size of WC is 0.6 μm.

[0042] Comparative Example 2 (two particle sizes)

[0043] Unlike Example 1, WC includes WC1 and WC2, with WC1 having a Fisher particle size of 0.6 μm and WC2 having a Fisher particle size of 1.0 μm. The mass ratio of WC1 to WC2 is 9:1.

[0044] Comparative Example 3 (two particle sizes)

[0045] Unlike Example 1, WC includes WC1 and WC2, with WC1 having a Fisher particle size of 0.7 μm and WC2 having a Fisher particle size of 1.5 μm. The mass ratio of WC1 to WC2 is 9:1.

[0046] Comparative Example 4 (two particle sizes)

[0047] Unlike Example 1, WC includes WC1 and WC2, with WC1 having a Fisher particle size of 0.8 μm and WC2 having a Fisher particle size of 1.0 μm. The mass ratio of WC1 to WC2 is 9:1.

[0048] Comparative Example 5 (three particle sizes, but with different particle size ranges)

[0049] Unlike Example 1, WC includes WC1, WC2 and WC3, with WC1 having a Fisher particle size of 1.2 μm, WC2 having a Fisher particle size of 0.5 μm and WC3 having a Fisher particle size of 0.2 μm. The mass ratio of WC1:WC2:WC3 is 1:0.3:0.1.

[0050] Performance tests were conducted on the above embodiments and comparative examples, and the test results are shown in Table 1.

[0051] (1) Alloy grain size test: The WC grain size of the material was tested according to GB / T3488.2—2018 "Metallographic determination of microstructure of cemented carbide".

[0052] (2) Alloy bending strength test: The bending strength of the material was tested according to GB / T3851-2015 "Method for Determination of Transverse Fracture Strength of Hard Alloy".

[0053] (3) Alloy hardness test: The Vickers hardness of the material is tested according to GB / T7997-2014 "Test Method for Vickers Hardness of Hard Alloy".

[0054] (4) Alloy fracture toughness test: The fracture toughness of the material was tested according to QJ / ZCC08.01.(CFL)6037-2018 "Test method for fracture toughness of cemented carbide - indentation method".

[0055] (5) Coercivity test of alloy: The coercivity of the material is tested according to GB / T3848-2017 "Method for determination of coercivity (magnetism) of cemented carbide".

[0056] (6) Cobalt magnetic test of alloy: The cobalt magnetic test of the material was carried out in accordance with GB / T23369-2009 "Standard test method for determination of magnetic saturation (MS) of cemented carbide".

[0057] Table 1. Sex test results of the examples and comparative examples.

[0058]

[0059]

[0060] Meanwhile, metallographic, SEM, and cutting tool wear diagrams were performed on Examples 1 and Comparative Examples 1-4, as well as for the cutting tool wear. See details below. Figure 1 and Figure 2 .

[0061] From Table 1 and Figures 1-3 As can be seen, the embodiments of the present invention improve fracture toughness without reducing wear resistance by using three different Fisher particle sizes of WC particles, while also exhibiting high bending strength. This can significantly improve the general machining life of cemented carbide bars. Moreover, the cutting test tools of Comparative Examples 1-4 showed severe edge wear. In addition, Comparative Example 1 only used one type of Fisher particle size, resulting in poor fracture toughness. Comparative Examples 2 and 3 used two Fisher particle size ranges, resulting in relatively poor bending strength and hardness. Comparative Example 4 used three Fisher particle size ranges with a large span, leading to poor bending strength. Therefore, both finishing and roughing processes can achieve good machining life, greatly enhancing product competitiveness.

[0062] The embodiments described above are merely preferred embodiments of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various other corresponding changes and modifications based on the technical solutions and concepts described above, and all such changes and modifications should fall within the protection scope of the claims of the present invention.

Claims

1. A manufacturing process for a non-uniform cemented carbide, characterized in that, Includes the following steps: S1: Mix WC, binder phase and inhibitor to obtain mixed powder, add forming agent, grinding media and ball milling media to mixed powder in sequence, turn on ball mill to mix materials to obtain mixed material; WC includes WC1, WC2 and WC3. The Fisher particle size of WC1 is 0.6-0.8 μm, the Fisher particle size of WC2 is 1.0-2.0 μm, and the Fisher particle size of WC3 is 3.0-5.0 μm. By mass ratio, WC1:WC2:WC3 = 6-8:0.5-1.5:1-3. S2: The mixture is dried and granulated in sequence, and then pressed into shape to obtain a pressed blank; S3: Dewaxing and sintering the pressed blank to obtain a non-uniform hard alloy.

2. The manufacturing process for a non-uniform cemented carbide according to claim 1, characterized in that, In step S1, the binder phase is Co or a mixture of Co and Ni; The WC content of the mixed powder is 85-95% by mass, the binder content of the mixed powder is 5-15% by mass, and the remainder is an inhibitor. The inhibitor comprises TaC and Cr3C2 in a mass ratio of 1:0.2-0.4; Mixed powder:forming agent:grinding media:ball milling media = 1:(0.02-0.03):(4-5):(350-400).

3. The manufacturing process for a non-uniform cemented carbide according to claim 1, characterized in that, In step S2, the pressure applied during the pressing process is 500-1000 MPa.

4. The manufacturing process for a non-uniform cemented carbide according to claim 1, characterized in that, In step S3, during dewaxing, the vacuum level in the vacuum furnace is 10-15 Pa, and the carrier gas flow rate is 1.5-3.5 m³ / s. 3 / h, temperature is 350-600℃, and the heat preservation time is 2-4h.

5. The manufacturing process for a non-uniform cemented carbide according to claim 1, characterized in that, In step S3, during sintering, the vacuum degree in the vacuum furnace is 0.01-0.05 Pa, the temperature is 1400-1420℃, and the holding time is 1-1.5 h.

6. A non-uniform cemented carbide, characterized in that, It is produced using the production process described in any one of claims 1-5.

7. A non-uniform cemented carbide according to claim 6, characterized in that, The hardness is greater than 1600 HV3, the tensile strength is greater than 3500 MPa, and the fracture toughness is greater than 11.5 MPa·m. 1 / 2 .

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