A method for producing cemented carbide with adjustable hardness

Abstract

The present application provides a kind of component hardness adjustable cemented carbide preparation method, comprising the following steps: step S1, preparation several functional compacts, matrix compacts;Step S2, after functional compacts and matrix compacts are assembled, sintering;Step S3, after cooling, obtain component hardness adjustable cemented carbide.The present application component hardness adjustable cemented carbide preparation method, using modular production mode, first make the compacts with different components, hardness, then the module compacts are assembled into finished compacts by assembling mode, and then put into sintering furnace for sintering, and component hardness adjustable cemented carbide is prepared, the problem that it is difficult to adjust the composition of cemented carbide and the problem that it is difficult to combine with the base material metallurgically when applied to the surface of large equipment wear-resistant parts is solved, the interface bonding strength of functional compacts-matrix compacts, matrix compacts-base material is improved, the technical requirements of surface modification of large equipment wear-resistant parts are met, and the performance indicators of extending service life are realized.

Description

Technical Field

[0001] This invention relates to the field of cemented carbide technology, and more specifically, to a method for preparing cemented carbide with adjustable composition and hardness. Background Technology

[0002] Gradient-structure cemented carbide is a novel alloy material that achieves a synergistic improvement in surface hardness and internal toughness through cross-sectional gradient changes in composition or structure. Patent CN105177336A discloses a method for rapidly preparing coarse-grained gradient cemented carbide. This involves pressing a carbon-depleted cemented carbide powder containing a certain proportion of ultrafine WC powder into shape, followed by pressure sintering to obtain a carbon-depleted pre-sintered matrix. The matrix is ​​then carburized at 1430-1460℃ for 60-150 minutes in a hydrogen atmosphere to obtain the gradient cemented carbide. The gradient layer thickness in the gradient cemented carbide is 200-2000 μm. Patent CN217628624U discloses a high-hardness cemented carbide round bar with a gradient structure, comprising an alloy round bar body. The outer surface of the alloy round bar body is coated with a gradient coating, which includes a connecting layer, a first hardness layer, and a second hardness layer. The connecting layer is disposed on the outer surface of the alloy round bar body, the first hardness layer is disposed on the outer surface of the connecting layer, and the second hardness layer is disposed on the outer surface of the first hardness layer.

[0003] Patent CN105177336A forms a reinforcing layer on the surface of cemented carbide through carburizing / nitriding; patent CN217628624U forms a reinforcing layer on the surface of cemented carbide by spraying a gradient coating on the outer surface. Existing gradient cemented carbide production processes are complex, requiring multiple processing steps using different equipment. The materials used are typically metals such as Co and Ni, which are expensive, resulting in high production costs. Furthermore, the need to change powders for pressing or spraying leads to low production efficiency. Adjusting the composition is difficult, and the adjustable range of nitriding / carburizing composition is narrow. Regardless of whether carburizing / nitriding or spraying is used, the thickness of the reinforcing layer is relatively thin, generally not exceeding 3mm, resulting in insufficient service life.

[0004] For scenarios where metallurgical bonding of cemented carbide is required on the surface of wear-resistant parts of large equipment, the bonding between cemented carbide and the base material is difficult, especially for WC-Co type cemented carbide which cannot achieve metallurgical bonding with the base material.

[0005] In view of this, the present invention is hereby proposed. Summary of the Invention

[0006] The purpose of this invention is to address the difficulties in adjusting the composition of cemented carbide and the difficulties in metallurgical bonding with the base material when applied to the surface of wear-resistant parts of large equipment in the existing technology. It provides a method for preparing cemented carbide with adjustable composition and hardness, which improves the interfacial bonding strength between the functional compact and the matrix compact, and between the matrix compact and the base material. This meets the technical requirements for surface modification of wear-resistant parts of large equipment and achieves the performance indicators of extending service life.

[0007] In order to achieve the above-mentioned objectives of the present invention, the following technical solution is adopted: A method for preparing a cemented carbide with adjustable composition and hardness includes the following steps: Step S1: Prepare several functional compacts and matrix compacts; Step S2: Assemble the functional compact and the base compact, and then sinter them; Step S3: After cooling, a cemented carbide with adjustable composition and hardness is obtained.

[0008] Furthermore, several functional compacts are several compacts with the same or different compositions and the same or different hardness.

[0009] Furthermore, the functional compact and the base compact are provided with protrusions and / or recesses.

[0010] Furthermore, the width a of the blank of the functional compact and the base compact is 12~60mm, the width b of the protrusion / recess is 6~35mm, the height c of the protrusion / recess is 5~20mm, and the height d of the blank is 10mm~35mm.

[0011] Furthermore, the proportion of carbides in the functional compact is 35~65wt%, and the Fisher particle size is ≤1.5μm; the proportion of binder phase is 35~65wt%, and the Fisher particle size is 5μm~10μm.

[0012] Furthermore, the proportion of carbides in the functional compact is 35-40 wt%, and the proportion of binder phase is 60-65 wt%.

[0013] Furthermore, the carbides in the functional compact include at least one of TiC and CrC.

[0014] Furthermore, the binder phase in the functional compact comprises the following components by weight: 35-55 parts iron, 2-25 parts manganese, 1-5 parts nickel, 1-5 parts molybdenum, and 0.5-2 parts niobium.

[0015] Furthermore, the substrate blank is made of alloy steel.

[0016] Furthermore, in step S2, the base compact and the functional compact are assembled with a clearance fit, with a clearance of <0.2 mm.

[0017] Furthermore, in step S2, the sintering adopts a gradient heating method, raising the temperature from 0℃ to 1100℃ within 6~8h, and raising the temperature from 1100℃ to 1400~1500℃ within 2~4h, and then holding it at that temperature for 0.5~1h.

[0018] Furthermore, the cooling method in step S3 is slow cooling with the furnace.

[0019] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. This invention discloses a method for preparing cemented carbide with adjustable composition and hardness. It employs a modular production approach, first creating compacts with different compositions and hardnesses, then assembling these modular compacts into finished compacts, which are then sintered in a sintering furnace to prepare cemented carbide with adjustable composition and hardness. The matrix compact can form a reliable metallurgical bond with the base material. This invention solves the problems of difficulty in adjusting the composition of cemented carbide and the difficulty in metallurgical bonding with the base material when applied to the surface of wear-resistant parts of large equipment. It improves the interfacial bonding strength between the functional compact and the matrix compact, and between the matrix compact and the base material, meeting the technical requirements for surface modification of wear-resistant parts of large equipment and achieving performance indicators that extend service life.

[0020] 2. The main function of Mo and Nb in the binder phase of the functional compact of this invention is to refine the grains and improve the wettability of carbide particles, thereby increasing the bonding strength between the carbide particles and the binder phase, and thus improving the mechanical properties of the finished material, which can produce ultrafine-grained cemented carbide.

[0021] 3. This invention does not use Co metal, and the amount of nickel metal used is also significantly reduced, which is significantly more advantageous in terms of cost control compared with existing processes.

[0022] 4. Due to the addition of a large amount of carbides, the functional layer of this invention can significantly improve the material hardness, and a metallurgical bond is formed at the interface without cracks or other phenomena. At the same time, the special interface design further improves the shear strength of the material. Attached Figure Description

[0023] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0024] Figure 1 This is a schematic diagram of the matrix compact structure of the present invention; Figure 2 This is a schematic diagram of a structure of the functional pressed blank of the present invention; Figure 3This is an assembly diagram of a single functional compact and a base compact of the present invention; Figure 4 This is another structural diagram of the functional pressed blank of the present invention; Figure 5 This is an assembly diagram of multiple functional compacts and a base compact of the present invention; Figure 6 The interface between the cemented carbide matrix compact and the functional compact was prepared in Example 1 of this invention. Figure 1 #; Figure 7 The interface between the cemented carbide matrix compact and the functional compact was prepared in Example 1 of this invention. Figure 2 #. Detailed Implementation

[0025] The technical solution of the present invention will be clearly and completely described below with reference to specific embodiments. However, those skilled in the art will understand that the embodiments described below are some embodiments of the present invention, but not all embodiments, and are only used to illustrate the present invention, and should not be regarded as limiting the scope of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall be followed. Where the manufacturers of reagents or instruments are not specified, they are all conventional products that can be purchased commercially.

[0026] A method for preparing a cemented carbide with adjustable composition and hardness includes the following steps: Step S1: Prepare several functional compacts and matrix compacts; Step S2: Assemble the functional compact and the base compact, and then sinter them; Step S3: After cooling, a cemented carbide with adjustable composition and hardness is obtained.

[0027] Preferably, the plurality of functional compacts are plurality of compacts having the same or different compositions and the same or different hardnesses. This invention can, according to the requirements of cemented carbide for the composition and hardness of multiple functional layers, set up multiple functional compacts with corresponding compositions and hardnesses, thereby producing cemented carbide with adjustable composition and hardness.

[0028] Preferably, the functional compacts and the base compacts are provided with protrusions and / or recesses. The protrusions and recesses of the several functional compacts and the base compacts of the present invention make the upper and lower parts of the compact more firmly bonded, preventing breakage at the interface due to lateral shearing.

[0029] Preferably, the width 'a' of the functional compact and the substrate compact is 12-60 mm (including but not limited to 12 mm, 18 mm, 24 mm, 30 mm, 36 mm, 42 mm, 48 mm, 54 mm, 60 mm), the width 'b' of the protrusion / recess is 6-35 mm (including but not limited to 6 mm, 10 mm, 15 mm, 20 mm, 25 mm, 30 mm), the height 'c' of the protrusion / depth of the recess is 5-20 mm (including but not limited to 5 mm, 10 mm, 15 mm, 20 mm), and the height 'd' of the compact is 10 mm-35 mm (including but not limited to 10 mm, 15 mm, 20 mm, 25 mm, 30 mm, 35 mm). The dimensions of the functional compact and the substrate compact of the present invention can be adjusted within a numerical range or proportionally scaled down according to the application scenario.

[0030] Preferably, the proportion of carbides in the functional compact is 35~65wt% (including but not limited to 35wt%, 40wt%, 45wt%, 50wt%, 55wt%, 60wt%, 65wt%, preferably 35~40wt%), and the Fisher particle size is ≤1.5μm; the proportion of binder phase is 35~65wt% (including but not limited to 35wt%, 40wt%, 45wt%, 50wt%, 55wt%, 60wt%, 65wt%, preferably 60~65wt%), and the Fisher particle size is 5μm~10μm.

[0031] Preferably, the carbides in the functional compact include at least one of TiC and CrC.

[0032] Preferably, the raw materials for the binder phase in the functional compact include: iron powder, ferromanganese powder (with a Mn content of 65wt%), nickel powder, molybdenum powder, and ferroniobium powder (with a niobium content of 65wt%). Mn volatilizes during the sintering process, so although the ferromanganese content is high during the preparation process, the Mn content in the finished product decreases due to volatilization.

[0033] Preferably, the binder phase in the functional compact comprises the following components by weight: 35-55 parts of iron (including but not limited to 35, 40, 45, 50, and 55 parts, preferably 40.5-51.5 parts), 2-25 parts of manganese (including but not limited to 2, 5, 10, and 15 parts, preferably 2-15 parts), 1-5 parts of nickel (including but not limited to 1, 2, 3, 4, and 5 parts, preferably 2-4 parts), 1-5 parts of molybdenum (including but not limited to 1, 2, 3, 4, and 5 parts, preferably 2 parts), and 0.5-2 parts of niobium (including but not limited to 0.5, 1, 1.5, and 2 parts, preferably 0.5 parts). The main functions of Mo and Nb are to refine the grain size and improve the wettability of carbide particles, thereby increasing the bonding strength between the carbide particles and the binder phase, and ultimately improving the mechanical properties of the finished material, thus producing an ultrafine-grained cemented carbide.

[0034] The cemented carbide of this invention does not use Co metal, and the amount of nickel metal used is also significantly reduced, which has a clear advantage in cost control compared with existing processes.

[0035] Preferably, the substrate compact is made of alloy steel, and more preferably low-carbon alloy steel or high-manganese steel. The use of alloy steel in the substrate compact allows for a reliable metallurgical bond with the base material through conventional joining and processing methods (such as welding), thereby improving the interfacial bonding strength between the substrate compact and the base material.

[0036] Preferably, in step S2, the base compact and the functional compact are assembled with a clearance fit, and the clearance is <0.2mm.

[0037] Preferably, in step S2, the sintering is carried out with a gradient temperature increase, from 0°C to 1100°C within 6-8 hours (including but not limited to 6 hours, 6.5 hours, 7 hours, 7.5 hours, and 8 hours), and from 1100°C to 1400-1500°C (including but not limited to 1400°C, 1420°C, 1450°C, 1480°C, and 1500°C, preferably 1450°C) within 2-4 hours (including but not limited to 2 hours, 2.5 hours, 3 hours, 3.5 hours, and 4 hours), and then held at that temperature for 0.5-1 hour (preferably 1 hour).

[0038] Preferably, the cooling method in step S3 is slow cooling with the furnace.

[0039] Example 1 A method for preparing a cemented carbide with adjustable composition and hardness (the dimensions and composition data of the matrix compact and the functional compact in Example 1 are shown in Table 1) includes the following steps: a. Prepare the matrix compact with the following dimensions: a-26mm, b-10mm, c-7mm, d-20mm; the matrix compact material is Mn18Cr2. b. Prepare functional compacts with dimensions of: a-26mm, b-10mm, c-7mm, d-20mm; the materials of the functional compacts include: TiC 35wt%, Mn 10wt%, Ni 4wt%, Mo 2wt%, Nb 0.5wt%, Fe 48.5wt%. c. Assemble the functional compact and the base compact into a finished compact, place it in a sintering furnace for vacuum sintering, and then hold it at 1450℃ for 1 hour after gradient heating. The gradient heating process is as follows: 6 hours from 0℃ to 1100℃, 2 hours from 1100℃ to 1450℃ and then hold it at 1 hour. d. Slow cooling in the furnace yields a cemented carbide with adjustable composition and hardness.

[0040] Example 2 The difference between this embodiment and embodiment 1 is that: the dimensions of the matrix compact in step a are: a-40mm, b-19mm, c-10mm, d-30mm; the material of the matrix compact is 42CrMo; the dimensions and composition data of the matrix compact and the functional compact in embodiment 2 are shown in Table 1. The dimensions of the functional compact in step b are: a-40mm, b-19mm, c-10mm, d-30mm; the materials of the functional compact include: CrC 40wt%, Mn 15wt%, Ni 2wt%, Mo 2wt%, Nb 0.5wt%, Fe 40.5wt%. The rest is the same as in Example 1.

[0041] Example 3 The difference between this embodiment and embodiment 1 is that: the dimensions of the substrate compact in step a are: a-16mm, b-10mm, c-7mm, d-20mm; the material of the substrate compact is high-V high-speed steel; the dimensions and composition data of the substrate compact and the functional compact in embodiment 3 are shown in Table 1. The dimensions of the functional compact in step b are: a-16mm, b-10mm, c-7mm, d-20mm; the materials of the functional compact include: CrC+TiC 40wt%, Mn 2wt%, Ni 4wt%, Mo 2wt%, Nb 0.5wt%, Fe 51.5wt%. The rest is the same as in Example 1.

[0042] The dimensions and composition data of the matrix compact and functional compact in Examples 1-3 are shown in Table 1.

[0043] Table 1. Dimensions and composition data of the matrix compacts and functional compacts in Examples 1-3

[0044] Test case I. Hardness tests were conducted according to GB / T 230.1-2018 "Metallic materials Rockwell hardness test - Part 1: Test method". The hardness test results of the functional layers of cemented carbide prepared in Examples 1-3 are shown in Table 2.

[0045] II. The shear strength was tested according to GB / T 6400-2007 "Test Method for Shearing of Metallic Materials Wire and Rivet". The interfacial shear strength test results of the cemented carbide prepared in Examples 1-3 are shown in Table 2.

[0046] Table 2. Test results of hardness and interfacial shear strength of the functional layers of the cemented carbide prepared in Examples 1-3

[0047] As shown in Table 2, the functional layers of cemented carbide prepared in Examples 1-3 significantly improved the material hardness due to the addition of a large number of carbide particles, while the special interface design further improved the material shear strength.

[0048] Example 1 prepared cemented carbide that can meet the requirements of medium-high impact and medium wear resistance, such as cone crusher liners; Example 2 prepared cemented carbide that can meet the requirements of medium impact and high wear resistance, such as cement clinker mills; Example 3 prepared cemented carbide that can meet the requirements of low impact and high wear resistance, such as vertical mill rollers.

[0049] III. Example 1: Preparation of the interface diagram between the cemented carbide matrix compact and the functional compact. (See attached diagram) Figures 6-7 .

[0050] like Figures 6-7 As shown, the left side is the functional compact and the right side is the matrix compact. The functional layer formed by the functional compact has a large amount of black TiC particles added, which can significantly improve the material hardness. The interface forms a metallurgical bond without cracks or other phenomena.

[0051] The methods for preparing composition and hardness adjustable cemented carbide in Examples 1-3 adopt a modular production approach. First, compacts with different compositions and hardness are made. Then, the modular compacts are assembled into finished compacts and placed in a sintering furnace for sintering to obtain cemented carbide with adjustable composition and hardness. The base compacts in Examples 1-3 are all made of alloy steel, which can form a reliable metallurgical bond with the base material through conventional connection and processing methods, thereby improving the interfacial bonding strength between the base compact and the base material.

[0052] This invention solves the problems of difficulty in adjusting the composition of cemented carbide and difficulty in metallurgical bonding with the base material when applied to the surface of wear-resistant parts of large equipment. It improves the interfacial bonding strength between functional compact and base compact, and between base compact and base material, meets the technical requirements for surface modification of wear-resistant parts of large equipment, and achieves the performance indicators of extending service life.

[0053] In Examples 1-3, the main role of Mo and Nb in the binder phase of the functional compact for preparing cemented carbide is to refine the grains and improve the wettability of carbide particles, thereby increasing the bonding strength between the carbide particles and the binder phase, and thus improving the mechanical properties of the finished material, which can produce ultrafine-grained cemented carbide.

[0054] The methods for preparing hard alloys with adjustable composition and hardness in Examples 1-3 do not use Co metal and the amount of nickel metal used is also significantly reduced, which has a significant advantage in cost control compared to existing processes.

[0055] The functional layers of cemented carbide prepared in Examples 1-3 significantly improve material hardness due to the addition of a large amount of carbides. Metallurgical bonding is formed at the interface without cracks or other phenomena. At the same time, the special interface design further improves the shear strength of the material.

Claims

1. A method for preparing a cemented carbide with adjustable composition and hardness, characterized in that, Includes the following steps: Step S1: Prepare several functional compacts and matrix compacts; Step S2: Assemble the functional compact and the base compact, and then sinter them; Step S3: After cooling, a cemented carbide with adjustable composition and hardness is obtained.

2. The method for preparing a cemented carbide with adjustable composition and hardness according to claim 1, characterized in that, Several functional compacts are several compacts with the same or different compositions and the same or different hardness.

3. The method for preparing a cemented carbide with adjustable composition and hardness according to claim 1, characterized in that, The functional compact and the base compact are provided with protrusions and / or recesses.

4. The method for preparing a cemented carbide with adjustable composition and hardness according to claim 3, characterized in that, The width a of the functional compact and the base compact is 12~60mm, the width b of the protrusion / recess is 6~35mm, the height c of the protrusion / recess is 5~20mm, and the height d of the compact is 10mm~35mm.

5. The method for preparing a cemented carbide with adjustable composition and hardness according to claim 1, characterized in that, The functional compact contains 35-65 wt% carbides with a Fisher particle size ≤ 1.5 μm and 35-65 wt% binder phase with a Fisher particle size of 5 μm-10 μm.

6. The method for preparing a cemented carbide with adjustable composition and hardness according to claim 5, characterized in that, The functional compact contains 35-40 wt% carbides and 60-65 wt% binder phase.

7. The method for preparing a cemented carbide with adjustable composition and hardness according to claim 5, characterized in that, The carbides in the functional compact include at least one of TiC and CrC.

8. The method for preparing a cemented carbide with adjustable composition and hardness according to claim 5, characterized in that, The binder phase in the functional compact comprises the following components by weight: 35-55 parts iron, 2-25 parts manganese, 1-5 parts nickel, 1-5 parts molybdenum, and 0.5-2 parts niobium.

9. The method for preparing a cemented carbide with adjustable composition and hardness according to claim 1, characterized in that, The substrate blank is made of alloy steel.

10. The method for preparing a cemented carbide with adjustable composition and hardness according to claim 1, characterized in that, Includes at least one of the following technical features: (1) In step S2, the base blank and the functional blank are assembled with a clearance fit, and the clearance is <0.2 mm; (2) In step S2, the sintering adopts a gradient temperature increase, from 0℃ to 1100℃ in 6~8h, and from 1100℃ to 1400~1500℃ in 2~4h, and then holds at the temperature for 0.5~1h; (3) The cooling method in step S3 is slow cooling with the furnace.

Images