High-speed steel knife blade as well as injection molding preparation method and application thereof

Abstract

The invention belongs to the field of high-speed steel, and particularly relates to a high-speed steel knife blade injection molding preparation method which comprises the following steps: preparing raw materials containing Ni, C, Cr, Mo, W, V, Co, Nb, a modifier and Fe; carrying out ball milling treatment on the mixed raw material to obtain powder; the powder is modified with a titanate coupling agent in advance, and modified powder is obtained; the modified powder and a polymer are mixed, then injection molding, sintering, heat treatment and polishing are conducted, and the high-speed steel knife particle is prepared. The chemical formula of the modifier is (Hf < x > Zr < y > Ta < z > TimMen) B < 2 >; me comprises at least one of V, W and Mo; x, y, z, m and n are independently 0.1-0.3, and x + y + z + m + n = 1. The performance of the prepared high-speed steel cutter blade can be improved, and particularly the nickel-free welding performance of the high-speed steel cutter blade can be improved.

Description

Technical Field

[0001] The invention relates to the field of high-speed steel, in particular to the field of high-speed steel knife particle preparation. Background Art

[0002] Conventional blades are mainly used in bimetallic band saws, welded composite band saws and other scenes. The main materials are cast and forged high-speed steel, powdered high-speed steel or WC-Co cemented carbide. However, conventional high-speed steel has insufficient wear resistance, while cemented carbide has insufficient toughness and is prone to chipping. Therefore, there is a lack of blade material with performance between high-speed steel and cemented carbide on the market, which is wear-resistant and anti-chipping.

[0003] In addition, conventional cemented carbide is prepared by a die-pressing-sintering method, while high-speed steel is prepared by rolling, forging or rotary forging to form a wire, and then by wire cutting.

[0004] For example, the Chinese patent document with publication number CN117300117A discloses the use of rotary forging to prepare high-speed steel wire, and then cutting and polishing to prepare band saw blades, but the hardness of the material prepared by the method is generally lower than 68HRC, and the prepared blades must be nickel-plated and can only be used for low-end products. The Chinese patent document with publication number CN114657325A discloses a wear-resistant high-speed steel and a preparation method thereof, wherein the high-speed steel is prepared by an in-situ generation method to generate boride-reinforced high-speed steel, but the method used is a casting method, which makes it difficult to efficiently prepare small-sized wear-resistant parts with high strength and hardness.

[0005] In summary, there are relatively few studies on existing high-speed steel blade particles, and the few preparation methods still have problems such as low molding efficiency and difficulty in preparing high-speed steel blade particles that can achieve high resistance welding strength without nickel plating. In addition, there is no technology in the industry to prepare high-speed steel blade particles by powder injection molding. Summary of the invention

[0006] In order to fill the technical gap in the injection molding preparation of high-speed steel blade particles, the first purpose of the present invention is to develop a method for injection molding preparation of high-speed steel blade particles, aiming to prepare high-speed steel blade particles with excellent properties such as high resistance welding strength without nickel plating based on an improved injection molding method.

[0007] The second purpose of the present invention is to provide high-speed steel blade particles obtained by the preparation method and applications thereof.

[0008] Although the injection molding process is a relatively mature method for preparing other alloys, the injection molding process for preparing high-speed steel blades is still a blank in the industry. The main reasons are: (1) Traditional high-speed steel injection molded parts are mostly made of atomized powder as raw materials and sintered using a super solid phase liquid phase sintering process. The structure is coarse and it is difficult to produce high-life and high-precision cutting tools, and it is even more difficult to meet the requirements of sawing blades; (2) When using ball-milled powder for injection molding, because the ball-milled powder is fine, the amount of traditional molding agent added is large, it is difficult to mix evenly, and the powder is prone to spontaneous combustion during heating and mixing. Subsequent sintering is also difficult to obtain full densification of solid phase sintering, so the structure and performance cannot meet the application requirements of blades. In response to this problem, the present invention provides the following improvement plan: A method for preparing high-speed steel blade particles by injection molding, comprising preparing a mixed raw material comprising a high-speed steel precursor raw material and a modifier, wherein the high-speed steel precursor raw material is a raw material comprising Ni, C, Cr, Mo, W, V, Co, Nb and Fe; ball milling the mixed raw material to obtain a powder; The powder is modified by a titanate coupling agent in advance to obtain a modified powder; the modified powder is mixed with a polymer, and then injection molded, sintered, heat treated, and polished to obtain the high-speed steel blade particles; The chemical formula of the modifier is: (Hf x Zr y Ta z Ti m Me n )B2; the Me comprises at least one of V, W, and Mo; the x, y, z, m, and n are independently 0.1 to 0.3, and the x+y+z+m+n=1.

[0009] In order to fill the problems faced by the injection molding preparation of high-speed steel blade particles, the present invention innovatively adds a certain amount of the above-mentioned modifier into the raw materials, based on the joint control of the modifier components, and further cooperates with the pre-modification of the titanate coupling agent. This can solve the problems faced by the injection molding preparation of high-speed steel blade particles, and can improve the performance of the prepared high-speed steel blade particles, especially the performance of their nickel-free welding.

[0010] In the present invention, the high-speed steel precursor raw material can be a single substance or an alloy of each element.

[0011] In the high-speed steel precursor raw material, the weight portion of Ni is 2.5-6.5 parts; The weight portion of C is 3.2-4.0 parts; The weight portion of Cr is 3.0-6.0 parts; The weight portion of Mo is 4.5-9.5 parts; The weight portion of W is 6.0-13.0 parts; The weight portion of V is 6.0-12.0 parts; The weight parts of Co are 9.0-13.0 parts; The weight portion of Nb is 1.0-2.0 parts; The weight proportion of Fe is 45 to 65 parts.

[0012] Preferably, the high-speed steel precursor raw material contains the following components in weight percentage: C: 3.2%-4.0%, Cr: 3.0%-6.0%, Ni: 2.5%-6.5%, Mo: 4.5%-9.5%, W: 6.0%-13.0%, V: 6.0%-12.0%, Co: 9.0%-13.0%, Nb: 1.0%-2.0%, and the balance is Fe; further preferably, C: 3.5%-4.0%, Cr: 4.0%-4.5%, Ni: 4.5%-5%, Mo: 7%-9%, W: 10%-12.0%, V: 8.0%-9.0%, Co: 11%-12.0%, Nb: 1.0%-1.5%, and the balance is Fe.

[0013] The present invention innovatively uses the components of the chemical formula to participate in ball milling and subsequent sintering processes, which can be combined with other operating parameters to help optimize the performance of high-speed steel blade particles prepared by injection molding, especially to improve their nickel-free welding performance.

[0014] In the present invention, in the modifier, x, y, z, m, and n are each 0.2±0.05, and preferably 0.2.

[0015] Preferably, the modifier accounts for 10-35% by weight of the high-speed steel precursor raw material; more preferably, it is 20.0%-30.0%.

[0016] Preferably, in the mixed raw material, the particle size of each component is 2.0-15.0 μm.

[0017] In the present invention, the ball milling is wet ball milling.

[0018] Preferably, a shaping agent is added during the ball milling stage.

[0019] Preferably, the molding agent is 3-6% by weight of the high-speed steel precursor material.

[0020] Preferably, the milling medium is alcohol.

[0021] Preferably, the abrasive material of ball milling is a cemented carbide ball.

[0022] Preferably, the ball milling time is 10 to 48 hours, and further can be 15 to 25 hours.

[0023] Preferably, the particle size of the powder after ball milling is ≤15 μm.

[0024] In the present invention, the powder and titanate coupling agent can be modified in advance, which is conducive to combining with other processes to synergistically optimize the performance of high-speed steel blade particles prepared by injection molding to meet sawing performance requirements, especially to improve its nickel-free welding performance.

[0025] In the present invention, during the modification process, the powder is placed in a solution containing a titanate coupling agent for modification treatment; the titanate coupling agent is 1-3% of the weight of the high-speed steel precursor raw material.

[0026] Preferably, the temperature in the modification stage is 45-55°C.

[0027] Preferably, the modification time is more than 1 hour, and can further be 1 to 4 hours.

[0028] In the present invention, the polymer includes an acrylic-based resin.

[0029] Preferably, the polymer accounts for 10-20% by weight of the high-speed steel precursor material, and further can be 13-16% by weight.

[0030] Preferably, the mixing temperature is 160-190°C.

[0031] Preferably, the temperature during the injection molding stage is 160-190°C.

[0032] Preferably, the injection pressure during the injection molding stage is 60-100 MPa.

[0033] In the present invention, the sintering process includes thermal debinding and gas pressure sintering processes; The temperature T1 of the thermal degreasing is 400-600°C, and the time is not less than 5 hours, and can further be 4-10 hours. The thermal degreasing process can include multiple processes of gradient temperature increase, wherein the temperature difference of each gradient can be 40-120°C. The single-stage processing time can be 1-5 hours.

[0034] The temperature of gas pressure sintering is 1100~1300℃, the pressure is 2.0-5.0MPa, and the time of gas pressure sintering is 2~5h.

[0035] In the present invention, the heat treatment process includes quenching, deep cooling and tempering processes; wherein the quenching process is carried out under vacuum, the temperature is 1180-1210°C, the holding time is not less than 30 minutes, and the quenching medium is an inert gas or oil; The cryogenic temperature is -80~-150℃, and the insulation time is not less than 8h; The tempering temperature is 580-650℃; the tempering times are 2~6 times, and each tempering time is not less than 1.5h.

[0036] The invention also provides a high-speed steel blade particle obtained by the preparation method.

[0037] The preparation method of the present invention can endow the prepared material with special physical and chemical characteristics, and the material with the characteristics prepared by the preparation method can unexpectedly and significantly improve the performance of the prepared high-speed steel blade particles.

[0038] The present invention also provides an application of high-speed steel blade particles obtained by the preparation method, which can be used to prepare band saws and / or welding composite strips. Compared with high-speed steel blade particles obtained by traditional casting and rolling methods and cutting, the blade particles prepared by the present invention can be free of nickel plating and directly realize high-strength resistance welding.

[0039] Beneficial effects: (1) The present invention is the first to prepare high-performance powder metallurgy high-speed steel blade particles based on the injection molding process, filling the gap in the industry.

[0040] (2) In view of the problems faced by the injection molding preparation of high-speed steel blade particles, the present invention innovatively uses a modifier to participate in the entire preparation process. In addition, by coordinating the control of processes such as polymer modification, it is possible to successfully achieve the injection molding preparation of high-performance high-speed steel blade particles. Not only that, it is also possible to optimize the microstructure of the material and improve its performance, especially to improve its nickel-free welding performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 is the sintered microstructure diagram in Example 1; Figure 2 This is a picture of the knife grain after polishing in Example 1; Figure 3 This is the welding macrostructure diagram in Example 1. DETAILED DESCRIPTION

[0042] The purpose of the present invention is to solve the above deficiencies in the prior art and to provide a powder high-speed steel-based composite material and a method for preparing knife particles.

[0043] In the following cases, the content of raw materials is weight percentage.

[0044] In the present invention, the dosage of the molding agent and the polymer is based on the weight of the high-speed steel precursor raw material.

[0045] Example 1 The high-speed steel precursor raw material composition ratio is C: 3.5%, Cr: 4.0%, Ni: 5.0%, Mo: 7.0%, W: 10.0%, V: 8.0%, Co: 12.0%, Nb: 1.0%, and the balance is Fe. 0.2 Zr 0.2 Ta 0.2 Ti 0.2 Me 0.2)B2, Me=V); modifier is 30% of the weight of the high-speed steel precursor raw material) to obtain a mixed raw material, add 5% of the molding agent (paraffin), put it into a planetary ball mill, the ball milling solvent is alcohol, the ball milling ball is a cemented carbide ball, and wet milling is 16 hours. The powder after ball milling is kept at 70℃ for 46 hours. The dried powder is placed in an alcohol solution of titanate coupling agent (titanate coupling agent is 1% of the weight of the high-speed steel precursor raw material) at a solution temperature of 45~55℃, soaked for more than 2 hours, and then dried in a vacuum stirring drying oven at 70℃ to obtain a modified powder.

[0046] The modified powder was put into an internal mixer, and acrylic resin was added, the resin accounted for 15% of the content of the high-speed steel precursor raw material, and the mixing temperature was 180°C to obtain a feed. After heating the feed to 180°C, it was injected into the mold with an injection pressure of 75MPa to obtain an injection molded blank, and the density of the injection molded blank was 4.8g / cm3.

[0047] The injection molding was debinded and sintered, with the hot debinding temperature being 450°C for 2 hours, 500°C for 4 hours, and 600°C for 2 hours; followed by gas pressure sintering, wherein the sintering gas pressure was 4.5MPa, the gas pressure sintering temperature was 1300°C, and the temperature was kept for 4 hours.

[0048] The sintered blade blank is subjected to vacuum quenching, deep cooling and three-time tempering treatments. The vacuum quenching temperature is 1200°C, and the insulation time is 45 minutes. The quenching medium is oil. The deep cooling temperature is -120°C, and the insulation time is 8 hours. The tempering temperature is 580°C, and each tempering time is 1.5 hours to obtain blade particles with a hardness of 73.5HRC. Figure 1 is the sintered microstructure diagram in Example 1; Figure 2 This is a picture of the knife grain after polishing in Example 1; Figure 3 This is the welding macrostructure diagram in Example 1, without nickel plating, and the average welding strength is 1150 MPa.

[0049] Example 2 The high-speed steel precursor raw material composition ratio is C: 4.0%, Cr: 4.5%, Ni: 4.5%, Mo: 9.0%, W: 12.0%, V: 9.0%, Co: 11.0%, Nb: 1.5%, and the balance is Fe. 0.2 Zr 0.2 Ta 0.2 Ti 0.2 Me 0.2)B2, Me=W)); modifier is 20% of the weight of the high-speed steel precursor raw material) to obtain a mixed raw material, add 4% of the weight of the high-speed steel precursor raw material molding agent (paraffin), put it into a planetary ball mill, the ball milling solvent is alcohol, the ball milling ball is a cemented carbide ball, and wet milling for 20 hours. The powder after ball milling is at 70℃ for 46 hours. The dried powder is placed in an alcohol solution of titanate coupling agent (titanate coupling agent is 1.5% of the weight of the high-speed steel precursor raw material), the solution temperature is 45~55℃, soak for more than 2 hours, and then dry it in a vacuum stirring drying oven at 70℃.

[0050] The modified powder was put into an internal mixer, and acrylic resin was added, the resin accounted for 13% of the content of the high-speed steel precursor raw material, and the mixing temperature was 180°C to obtain a feed. After heating the feed to 180°C, it was injected into the mold with an injection pressure of 75MPa to obtain an injection molded blank, and the density of the injection molded blank was 4.6g / cm3.

[0051] The injection molding was debinded and sintered, with the hot debinding temperature being 450°C for 2 hours, 500°C for 4 hours, and 600°C for 2 hours; followed by gas pressure sintering, wherein the sintering gas pressure was 3.5MPa, the gas pressure sintering temperature was 1200°C, and the temperature was kept for 3 hours.

[0052] The blade sintered blank was vacuum quenched, deep cooled and tempered three times. The vacuum quenching temperature was 1180℃, and the temperature was kept for 50min. The quenching medium was oil. The deep cooling temperature was -120℃, and the temperature was kept for 10h. The tempering temperature was 620℃, and each tempering was 2h. The blade hardness after heat treatment was 74.0HRC. It was not nickel-plated, and the average welding strength was 1130MPa.

[0053] Example 3 Step 1: The composition ratio of the high-speed steel precursor raw material is C: 3.5%, Cr: 4.0%, Ni: 5.0, Mo: 7.0%, W: 10.0%, V: 8.0%, Co: 12.0%, Nb: 1.0%, and the balance is Fe. 0.2 Zr 0.2 Ta 0.2 Ti 0.2 Me 0.2 )B2, Me=Mo)); the modifier is 25% of the weight of the high-speed steel precursor raw material) to obtain a mixed raw material, add a molding agent (paraffin) of 5% of the weight of the high-speed steel precursor raw material, put it into a planetary ball mill, the ball milling solvent is alcohol, the ball milling ball is a cemented carbide ball, and wet milling is 16 hours. The powder after ball milling is heated at 70°C for 46 hours.

[0054] Step 2: The dried powder was placed in an alcohol solution of a titanate coupling agent (the titanate coupling agent was 1.0% of the weight of the high-speed steel precursor material) at a solution temperature of 45-55°C for more than 2 hours, and then dried in a vacuum stirring drying oven at 70°C.

[0055] Step 3: The modified powder was put into an internal mixer, and acrylic resin was added, the resin accounted for 15% of the content of the high-speed steel precursor raw material, and the mixing temperature was 180°C to obtain a feed. After heating the feed to 180°C, it was injected into the mold with an injection pressure of 75MPa to obtain an injection molded blank, and the density of the injection molded blank was 4.8g / cm3.

[0056] Step 4: The injection molding was debinded and sintered, with the hot debinding temperature being 450°C for 2 hours, 500°C for 4 hours, and 600°C for 2 hours; followed by gas pressure sintering, wherein the sintering gas pressure was 4.0 MPa, the gas pressure sintering temperature was 1300°C, and the temperature was kept for 4 hours.

[0057] The sintered blade blank was quenched, deep cooled and tempered three times. The vacuum quenching temperature was 1200℃, and the temperature was kept for 45 minutes. The quenching medium was oil. The deep cooling temperature was -120℃, and the temperature was kept for 8 hours. The tempering temperature was 580℃, and each tempering was 1.5 hours to obtain the blade.

[0058] The test shows that the hardness of the blade is 73.2HRC. Without nickel plating, the average welding strength is 1180MPa.

[0059] Comparative Example 1 Compared with Example 3, the only difference is that in step 1, no modifier is added, and other operations and parameters are the same as in Example 1.

[0060] The obtained blade has a hardness of 69.0HRC. It is not nickel-plated, and the average welding strength is 700MPa, with a small amount of welding cracks.

[0061] Comparative Example 2 Compared with Example 3, the only difference is that in step 1, an equal amount of aluminum oxide is used as a modifier, and other operations and parameters are the same as in Example 1.

[0062] The hardness of the obtained blade is 35~40HRC. Welding cracks occur when the blade is not nickel-plated.

[0063] Comparative Example 3 Compared with Example 3, the only difference is that the processing of step 2 is not carried out, and the processing of step 1 and subsequent steps is carried out as a raw material.

[0064] The results show that when the feed material is heated to 180℃ and then injected into the mold with an injection pressure of 75MPa, the powder spontaneous combustion occurs, and the resin is not sufficient to wet the powder, resulting in injection molding failure.

[0065] Comparative Example 4 Compared with Example 3, the only difference is that in step 2, a silane coupling agent is used to replace the phthalate coupling agent, and other operations and parameters are the same as those in Example 1.

[0066] The strength of the injection molded blank is low and the injection molding fails.

Claims

1. A method for preparing high-speed steel blade particles by injection molding, characterized in that: Preparing a mixed raw material comprising a high-speed steel precursor raw material and a modifier, wherein the high-speed steel precursor raw material is a raw material comprising Ni, C, Cr, Mo, W, V, Co, Nb and Fe; ball-milling the mixed raw material to obtain a powder; The powder is modified by a titanate coupling agent in advance to obtain a modified powder; the modified powder is mixed with a polymer, and then injection molded, sintered, heat treated, and polished to obtain the high-speed steel blade particles; The chemical formula of the modifier is: (Hf x Zr y Ta z Ti m Me n )B2; the Me comprises at least one of V, W, and Mo; the x, y, z, m, and n are independently 0.1 to 0.3, and the x+y+z+m+n=1.

2. The method for preparing high-speed steel blade particles by injection molding according to claim 1, characterized in that: In the high-speed steel precursor raw material, the weight portion of Ni is 2.5-6.5 parts; The weight portion of C is 3.2-4.0 parts; The weight portion of Cr is 3.0-6.0 parts; The weight portion of Mo is 4.5-9.5 parts; The weight portion of W is 6.0-13.0 parts; The weight portion of V is 6.0-12.0 parts; The weight parts of Co are 9.0-13.0 parts; The weight portion of Nb is 1.0-2.0 parts; 45-65 parts by weight of Fe; Preferably, the high-speed steel precursor raw material contains the following components in weight percentage: C: 3.2%-4.0%, Cr: 3.0%-6.0%, Ni: 2.5%-6.5%, Mo: 4.5%-9.5%, W: 6.0%-13.0%, V: 6.0%-12.0%, Co: 9.0%-13.0%, Nb: 1.0%-2.0%, and the balance is Fe.

3. The method for preparing high-speed steel blade particles by injection molding according to claim 1 or 2, characterized in that: In the modifier, x, y, z, m, and n are each 0.2±0.05; preferably 0.2; Preferably, the modifier is 10-35% by weight of the high-speed steel precursor material.

4. The method for preparing high-speed steel blade particles by injection molding according to claim 1, characterized in that: The ball milling is wet ball milling; Preferably, a shaping agent is added during the ball milling stage; Preferably, the forming agent is 3-6% by weight of the high-speed steel precursor raw material; Preferably, the ball milling medium is alcohol; Preferably, the abrasive of the ball mill is a cemented carbide ball; Preferably, the ball milling time is 10 to 48 hours; Preferably, the particle size of the powder after ball milling is ≤15 μm.

5. The method for preparing high-speed steel blade particles by injection molding according to claim 1, characterized in that: During the modification process, the powder is placed in a solution containing a titanate coupling agent for modification; Preferably, the titanate coupling agent is 1-3% by weight of the high-speed steel precursor material; Preferably, the temperature in the modification stage is 45-55°C; Preferably, the modification time is more than 1 hour.

6. The method for preparing high-speed steel blade particles by injection molding according to claim 1, characterized in that: The polymers include acrylic-based resins; Preferably, the polymer is 10-20% by weight of the high-speed steel precursor material; Preferably, the mixing temperature is 160-190°C; Preferably, the temperature during the injection molding stage is 160-190°C; Preferably, the injection pressure during the injection molding stage is 60-100 MPa.

7. The method for preparing high-speed steel blade particles by injection molding according to claim 1, characterized in that: The sintering process includes thermal debinding and gas pressure sintering process; The degreasing temperature T1 is 400-600°C, the time is not less than 5 hours, and can be further 4-10 hours; the gas pressure sintering temperature is 1100-1300°C, the pressure is 2.0-5.0MPa, and the gas pressure sintering time is 2-5 hours.

8. The method for preparing high-speed steel blade particles by injection molding according to claim 1, characterized in that: The heat treatment process includes quenching, deep cooling and tempering. The quenching process is carried out under vacuum, the temperature is 1180~1210℃, the holding time is not less than 30min, and the quenching medium is inert gas or oil. The cryogenic temperature is -80~-150℃, and the insulation time is not less than 8h; The tempering temperature is 580-650℃; the tempering times are 2~6 times, and each tempering time is not less than 1.5h.

9. A high-speed steel blade pellet obtained by the injection molding preparation method according to any one of claims 1 to 8.

10. An application of high-speed steel blade particles prepared by the injection molding preparation method according to any one of claims 1 to 8, characterized in that: will prepare bandsaw and / or weld composite strips; Preferably, it is nickel-free welded to produce sawn and / or welded composite strips.

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