Alloy molybdenum wire for wire cutting and preparation method thereof

Abstract

This invention relates to the field of alloy molybdenum wire technology, and provides an alloy molybdenum wire for wire EDM and its preparation method, comprising the following components: molybdenum powder, rare earth oxides, metal powder, and WC-modified Al-Mg-Nb powder; the doping amount of rare earth oxides is 0.7~1.1 wt% of the weight of molybdenum powder, and the doping amount of metal powder is 5~15 wt% of the weight of molybdenum powder; the doping amount of WC-modified Al-Mg-Nb powder is 0.5~1.5 wt% of the weight of molybdenum powder; the preparation method includes the following steps: molybdenum powder, rare earth oxides, and metal powder are doped and then isostatically pressed, pre-sintered, and WC-modified Al-Mg-Nb-Sc powder is added and sintered again, and then cooled in the furnace to obtain a molybdenum alloy billet; the sintered molybdenum alloy billet is hot-rolled into a molybdenum wire rod; the molybdenum wire rod is then subjected to at least one rotary forging, hot drawing, annealing, and high-speed cold drawing to obtain the alloy molybdenum wire for wire EDM; this allows the final molybdenum alloy to exhibit superior strength, high-temperature stability, and crack resistance when used for EDM wire cutting.

Description

Technical Field

[0001] This invention relates to the field of alloy molybdenum wire technology, and more specifically, to an alloy molybdenum wire for wire cutting and its preparation method. Background Technology

[0002] Wire electrical discharge machining (EDM) technology is widely used in mold manufacturing, precision parts processing, and other fields due to its high precision and flexibility. Molybdenum wire, as the core electrode wire, directly determines processing efficiency, accuracy, and cost. With the increasing demand for thick workpieces and high-efficiency processing in the manufacturing industry, higher requirements are being placed on the strength, high-temperature stability, crack resistance, and service life of molybdenum wire.

[0003] In the existing technology, relevant patents have made many explorations, but there are still obvious limitations. For example, Chinese patent with publication number CN115305398A discloses a molybdenum wire for ultra-high current wire cutting, which uses only lanthanum oxide or cerium oxide as a single rare earth oxide doping. Although the strength is improved, its high temperature wear resistance is insufficient, the crack rate is high, and it is difficult to adapt to long-term processing of workpieces with a thickness of more than 250mm. Summary of the Invention

[0004] The purpose of this invention is to provide an alloy molybdenum wire for wire EDM and a method for preparing the same, which results in the final molybdenum alloy exhibiting superior strength, high-temperature stability, and crack resistance when used in wire EDM.

[0005] The embodiments of the present invention are achieved through the following technical solutions: This invention provides an alloy molybdenum wire for wire cutting, comprising the following components: molybdenum powder and additives, wherein the additives include rare earth oxides, metal powders, and WC-modified Al-Mg-Nb powder; the doping amount of the rare earth oxides is 0.7~1.1 wt% of the weight of the molybdenum powder, the doping amount of the metal powder is 5~15 wt% of the weight of the molybdenum powder, and the doping amount of the WC-modified Al-Mg-Nb powder is 0.5~1.5 wt% of the weight of the molybdenum powder.

[0006] The present invention also provides a method for preparing alloy molybdenum wire for wire cutting, comprising the following steps; Molybdenum powder, rare earth oxides and metal powder are doped to prepare a uniform powder, which is then isostatically pressed, pre-sintered, and then sintered again after adding WC-modified Al-Mg-Nb-Sc powder. After furnace cooling, a molybdenum alloy billet is obtained. The sintered molybdenum alloy billet is hot-rolled into molybdenum wire rods. The molybdenum wire rod is then subjected to at least one rotary forging, at least one hot drawing process, at least one annealing, and high-speed cold drawing to obtain the alloy molybdenum wire for wire cutting.

[0007] The technical solutions of the embodiments of the present invention have at least the following advantages and beneficial effects: This invention uses high-purity molybdenum powder as the matrix material. Through the synergistic effect of refining the grains by doping with rare earth oxides and strengthening the matrix with metal powder, the tensile strength, wear resistance, and high-temperature stability of the alloy molybdenum wire are better improved. More importantly, WC-modified Al-Mg-Nb-Sc powder is also doped, which disperses and strengthens the high strength and toughness of the molybdenum powder alloy. Furthermore, the pinned grain boundaries formed between the powder particles significantly improve the high-temperature creep resistance and crack resistance of the molybdenum alloy. As a result, the final molybdenum alloy exhibits superior strength, high-temperature stability, and crack resistance when used for wire EDM. Attached Figure Description

[0008] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0009] Figure 1 This is an appearance diagram of the finished molybdenum wire (with a graphite layer on the surface) obtained in Example 1 of the present invention. Figure 2 This is a 0.18mm electron microscope image of the finished molybdenum wire obtained in Example 1 of the present invention. Figure 3 The image shows the EBSD microstructure of the 0.18 mm cross-section of the finished molybdenum wire prepared in Example 1 of this invention. Detailed Implementation

[0010] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments whose manufacturers are not specified are all conventional products that can be purchased commercially.

[0011] The following is a detailed description of an alloy molybdenum wire for wire cutting and its preparation method provided by an embodiment of the present invention.

[0012] A molybdenum alloy wire for wire EDM comprises the following components: molybdenum powder and additives, wherein the additives include rare earth oxides, metal powders, and WC-modified Al-Mg-Nb powder; the weight ratio of Al powder, Mg powder, Nb powder, and Sc powder in the Al-Mg-Nb-Sc powder is 70-90:9-10:0.01-0.1:0.01-0.1; Among them, the molybdenum powder has a purity of ≥99.5%; Furthermore, the rare earth oxide is selected from at least one of lanthanum oxide, cerium oxide, and yttrium oxide, and the doping amount is 0.7~1.1wt% of the weight of molybdenum powder. Through multiple experiments, the inventors found that the doping amount of rare earth oxide within this range can refine the grains of the molybdenum billet through the dispersion strengthening effect, obtain a uniform fine-grained structure, and avoid the problem of increased crack rate caused by excessive content. The particle size is controlled at 0.5~4.0μm to ensure uniform distribution in the molybdenum matrix and achieve the best strengthening effect.

[0013] Furthermore, the metal powder is selected from at least one of tungsten powder, niobium powder, tantalum powder, vanadium powder, and rhenium powder, with a doping amount of 5-15 wt% of the molybdenum powder weight. Tungsten, niobium, and other metal elements have good compatibility with molybdenum and can form a solid solution strengthening effect, improving the room temperature and high temperature strength of the molybdenum wire, while also enhancing the wear resistance of the molybdenum wire. The particle size is also controlled at 0.5-4.0 μm to ensure synergistic dispersion with rare earth oxides and avoid local enrichment that could lead to defects.

[0014] Furthermore, the doping amount of WC-modified Al-Mg-Nb powder is 0.5~1.5 wt% of the weight of molybdenum powder.

[0015] Preferably, the doping amount of rare earth oxides is 0.7~0.9 wt% of the weight of molybdenum powder; the doping amount of metal powder is 10~15 wt% of the weight of molybdenum powder; and the doping amount of WC-modified Al-Mg-Nb powder is 0.5~1.0 wt% of the weight of molybdenum powder.

[0016] It should be noted that the preparation method of WC-modified Al-Mg-Nb-Sc powder is as follows: WC powder is added to Al-Mg-Nb-Sc powder, and the powder is wet-milled for 15-20 hours to ensure that the WC powder is uniformly dispersed in the Al-Mg-Nb-Sc powder. After drying at 70-100℃ for 5-8 hours, WC-modified Al-Mg-Nb-Sc powder material is obtained. The WC powder accounts for 10wt%-20wt% of the Al-Mg-Nb-Sc powder.

[0017] This invention uses high-purity molybdenum powder as the matrix material. Through the synergistic effect of refining the grain size with rare earth oxides and strengthening the matrix with metal powder, the tensile strength, wear resistance, and high-temperature stability of the alloy molybdenum wire are significantly improved. More importantly, it also incorporates WC-modified Al-Mg-Nb-Sc powder. The grain refinement, dislocation strengthening, and precipitation strengthening in the Al-Mg-Nb-Sc multi-element alloy powder effectively improve the yield strength and deformation resistance of the material, resulting in a significant increase in the tensile strength of the alloy, exhibiting high strength and excellent ductility. Furthermore, the WC-modified Al-Mg-Nb-Sc powder forms a double layer of Al-Mg-Nb-Sc powder encapsulating WC powder. The phase structure can reduce the porosity of Al-Mg-Nb-Sc powder and enhance its compactness, which is conducive to its subsequent bonding with molybdenum powder, rare earth oxides and metal powders during sintering. More importantly, the coherent strengthening mechanism of the WC-modified Al-Mg-Nb-Sc multi-component powder involves the local strain field generated by the coherent precipitates in the alloy. This strain field can form a pinning grain boundary effect on the movement of dislocations. This pinning grain boundary significantly controls grain growth, thereby improving the thermal stability of the material and thus enhancing the high-temperature creep resistance and crack resistance of the molybdenum alloy. As a result, the final molybdenum alloy exhibits better strength, high-temperature stability and crack resistance when used for wire EDM.

[0018] A method for preparing an alloy molybdenum wire for wire cutting includes the following steps; Molybdenum powder, rare earth oxides and metal powder are doped to prepare a uniform powder, which is then isostatically pressed, pre-sintered, and then sintered again after adding WC-modified Al-Mg-Nb-Sc powder. After furnace cooling, a molybdenum alloy billet is obtained. The sintered molybdenum alloy billet is hot-rolled into molybdenum wire rods. The molybdenum wire rod is then subjected to at least one rotary forging, at least one hot drawing process, at least one annealing, and high-speed cold drawing to obtain the alloy molybdenum wire for wire cutting.

[0019] More specifically, its preparation method includes the following steps; S1. Molybdenum powder, rare earth oxides and metal powder are mixed and doped using any one or more of the following methods: dry doping, solid-liquid doping or mixed doping, and then sieved to obtain a uniformly mixed alloy powder. For example, dry doping can be carried out as follows: molybdenum powder, rare earth oxides and metal powder are placed in a powder mixer and a protective gas (such as argon, nitrogen, etc.) is introduced, and the mixing time is 12-36 hours. S2. Isostatic pressing: The alloy powder is loaded into the rubber sleeve mold, the air is removed and sealed, and isostatic pressing is performed. The pressure in the isostatic press is increased to 180~220MPa and held for 3~6 minutes. After the pressure is reduced to normal pressure, the material blank is taken out to obtain the material blank. Ensure that the blank has uniform density and no internal pores to ensure the compactness and strength of the blank. S3, Sintering process: S31. Pre-sintering: The pressed compact is placed in a hydrogen atmosphere sintering furnace, heated to 1830~2100℃, held for 4~6 hours, and cooled with the furnace to obtain a density of 9.6~9.9 g / cm³. 3 The pre-sintered material; the hydrogen atmosphere can prevent the oxidation of molybdenum wire, and high-temperature sintering ensures that all components diffuse fully and form a stable alloy structure; S32. Re-sintering: Add WC-modified Al-Mg-Nb-Sc powder to the pre-sintering material and continue sintering in a hydrogen atmosphere. During sintering, keep the temperature at 2200~2350℃ for 2~3h to obtain molybdenum alloy billet. This invention involves adding molybdenum powder, rare earth oxide metal powder, and WC-modified Al-Mg-Nb-Sc powder in steps during sintering, resulting in a final molybdenum alloy powder with good dispersion. Furthermore, during the re-sintering process, WC can lower the nucleation barrier, facilitating crystallization and affecting sintering density, thereby influencing the hardness of the multiphase alloy. This solves the problem of easy wire breakage during the processing of thick molybdenum wire workpieces in the prior art, making the finished product less prone to breakage. S4. Hot Continuous Rolling: The molybdenum alloy billet is hot continuously rolled using an elliptical-round-dip two-roll mill at a rolling temperature of 1400~1500℃ and a final speed of 10~15m / s to produce molybdenum alloy wire rods with a diameter of φ5.0±2.0mm. The elliptical-round-dip design avoids the formation of ears and cracks during rolling, ensuring the surface quality and dimensional accuracy of the wire rod. S5. Rotary forging: Using carbide dies, the molybdenum wire rod is subjected to at least 3 passes of rotary forging. The rotary forging temperature is 1300~1500℃, the speed is 3~4m / min, and the deformation per pass is 15%~30%. Carbide dies are used to improve the surface finish of the alloy, and multi-pass rotary forging further refines the grains and enhances the toughness of the wire. S6. Hot drawing process: The hot drawing process is divided into a coarse specification stage and a fine specification stage. In the coarse specification stage, the wire is heated in a 1-2m long heating zone at a temperature of 700-900℃ and a speed of 2-10m / min. In the fine specification stage, multi-die drawing is used at a speed of 20-50m / min. The deformation per hot drawing pass is 20-30%, and the wire diameter is gradually reduced to ensure uniform processing. S7. Annealing treatment: Annealing temperature 1100~1500℃, speed 1~7m / min, adjust the uniformity of the filament structure and balance the strength and toughness by medium frequency induction heating; S8. High-speed cold drawing: Before cold drawing, coat the surface of the wire with a specific gravity of 1.0~1.05g / cm³. 3 The graphite emulsion is dried, and the cold drawing temperature is room temperature. The drawing speed is 150~400m / min, and the deformation per cold drawing pass is 10~20%, finally producing the finished molybdenum wire.

[0020] This invention further reduces the crack rate by adjusting the isostatic pressure, sintering process, rolling temperature, and cold drawing pretreatment process; for the processing requirements of thick workpieces, the cutting stability and efficiency are better, the crack level control is more stringent (A0~A2 level, 15% alarm threshold number <200), and the wire breakage rate is significantly reduced.

[0021] It should be noted that the following conditions apply to the flaw detection and cutting inspection of finished molybdenum wire products: Flaw detection conditions: Eddy current flaw detectors were used to inspect φ0.18mm molybdenum wire products. Crack levels were defined according to the 15% alarm threshold number of points, as shown in Table 1. Table 1 - Crack Classification of φ0.18mm Molybdenum Wire Finished Products After Eddy Current Testing

[0022] Cutting conditions: Use a power supply unit (model 400), voltage 5V, working current 5A, working fluid is "Dick" water-based, liquid ratio is 1:5, workpiece material is 45# steel, thickness 250mm.

[0023] Example 1 This embodiment provides an alloy molybdenum wire for wire cutting, comprising the following components: molybdenum powder with a purity of 99.6%, lanthanum oxide, tungsten powder, niobium powder, and WC-modified Al-Mg-Nb powder; the particle size of lanthanum oxide, tungsten powder, and niobium powder is 3.0 μm. The weight ratio of Al powder, Mg powder, Nb powder, and Sc powder in Al-Mg-Nb-Sc powder is 80:9.5:0.05:0.03. The doping amount of lanthanum oxide is 0.82 wt% of the weight of molybdenum powder, the doping amount of tungsten powder is 10 wt% of the weight of molybdenum powder, the doping amount of niobium powder is 2 wt% of the weight of molybdenum powder, and the doping amount of WC-modified Al-Mg-Nb powder is 1 wt% of the weight of molybdenum powder.

[0024] The preparation method of WC-modified Al-Mg-Nb-Sc powder is as follows: Al powder, Mg powder, Nb powder, and Sc powder were mixed in a weight ratio of 80:10:0.05:0.1, and WC powder was added. The mixture was then wet-milled for 15 hours and dried at 80°C for 7 hours to obtain WC-modified Al-Mg-Nb-Sc powder material. The WC powder accounted for 15% of the total weight of Al powder, Mg powder, Nb powder, and Sc powder.

[0025] This embodiment also provides a method for preparing the above-mentioned alloy molybdenum wire for wire cutting, including the following steps: S1. Place molybdenum powder, rare earth oxides and metal powder in a powder mixer and introduce argon gas. Mix for 12 hours and then sieve to obtain a uniformly mixed alloy powder. S2. Isostatic pressing: The alloy powder is loaded into the rubber sleeve mold, the air is removed and sealed, and isostatic pressing is performed. The pressure is increased to 190MPa in the isostatic press and held for 5 minutes. The diameter of the compact is φ64mm. After the pressure is reduced to normal pressure, it is taken out to obtain the material compact. S3, Sintering process: S31. Pre-sintering: The pressed compact is placed in a hydrogen atmosphere sintering furnace, heated to 1900℃, held for 5 hours, and cooled with the furnace to obtain a density of 9.7 g / cm³. 3 Pre-sintered materials; S32. Re-sintering: Add the above-mentioned WC-modified Al-Mg-Nb-Sc powder to the pre-sintering material, and continue sintering under a hydrogen atmosphere. During sintering, the temperature is held at 2200℃ for 3 hours to obtain a molybdenum alloy billet. S4. Hot continuous rolling: The molybdenum alloy billet is hot continuously rolled using an elliptical-round-hole two-roll mill at a rolling temperature of 1450℃ and a final speed of 14m / s to roll the molybdenum alloy billet into a φ5.0mm molybdenum wire rod. S5. The molybdenum wire rod obtained above is subjected to three rounds of rotary hammer beating, two hot drawing processes, and one cold drawing process, with annealing treatment in between, to produce finished molybdenum wire. The process includes: rotary forging using cemented carbide dies, performing three-pass rotary forging of molybdenum wire rod at a temperature of 1450℃, a speed of 3.5m / min, and a deformation per pass of 25%; coarse-gauge hot drawing using a 1.2m long heating zone at 800℃ and a speed of 6m / min; fine-gauge stage using multi-die drawing at 38m / min and a deformation per pass of 25%; annealing at 1300℃ and a speed of 4m / min; and coating the wire surface with a specific gravity of 1.02g / cm³ before cold drawing. 3 The graphite emulsion was dried, the cold drawing temperature was room temperature, the drawing speed was 250 m / min, and the deformation per cold drawing pass was 16%.

[0026] The finished molybdenum wire prepared in this embodiment has the following properties: crack grade A0 (8 alarm threshold points), room temperature tensile strength 3160 MPa, high temperature tensile strength at 1200℃ 1180 MPa, withstand current >12A, and cutting area 320,000 mm². 2 Cutting time: 45.9 hours; Cutting efficiency: 0.69717 million mm. 2 / h.

[0027] The finished molybdenum wire obtained in this embodiment is shown in the following figure. Figure 1 The resulting molybdenum wire was then subjected to a 0.18 mm microscopic electron microscope scan, as detailed in the following figure. Figure 2 The resulting molybdenum wire underwent EBSD microstructure testing at a 0.18 mm cross-section, and the results are shown in the table below. Figure 3 .

[0028] Example 2 The difference between this embodiment and Embodiment 1 is that: an alloy molybdenum wire for wire cutting includes the following components: molybdenum powder with a purity of 99.6%, lanthanum oxide, cerium oxide, tungsten powder, and WC-modified Al-Mg-Nb powder; the particle size of lanthanum oxide, cerium oxide, and tungsten powder is 2.5 μm. The weight ratio of Al powder, Mg powder, Nb powder, and Sc powder in Al-Mg-Nb-Sc powder is 75:10:0.03:0.05. The doping amount of lanthanum oxide is 0.4 wt% of the weight of molybdenum powder, the doping amount of cerium oxide is 0.3 wt% of the weight of molybdenum powder, the doping amount of tungsten powder is 10 wt% of the weight of molybdenum powder, and the doping amount of WC-modified Al-Mg-Nb powder is 1.2 wt% of the weight of molybdenum powder.

[0029] The finished molybdenum wire prepared in this embodiment has the following properties: crack grade A2 (180 alarm threshold points), room temperature tensile strength 3080 MPa, high temperature tensile strength at 1200℃ 1080 MPa, withstand current >12A, and cutting area 330,000 mm². 2 Cutting time: 45.3 hours; Cutting efficiency: 0.72848 million mm. 2 / h.

[0030] Example 3 The difference between this embodiment and Embodiment 1 is that: an alloy molybdenum wire for wire cutting includes the following components: molybdenum powder with a purity of 99.5%, lanthanum oxide, yttrium oxide, tungsten powder, and WC-modified Al-Mg-Nb powder; the particle size of lanthanum oxide, cerium oxide, and tungsten powder is 3.5 μm. The weight ratio of Al powder, Mg powder, Nb powder, and Sc powder in Al-Mg-Nb-Sc powder is 85:9.3:0.07:0.02. The doping amount of lanthanum oxide is 0.4 wt% of the weight of molybdenum powder, the doping amount of cerium oxide is 0.3 wt% of the weight of molybdenum powder, the doping amount of tungsten powder is 10 wt% of the weight of molybdenum powder, and the doping amount of WC-modified Al-Mg-Nb powder is 1.1 wt% of the weight of molybdenum powder.

[0031] The finished molybdenum wire prepared in this embodiment has the following properties: crack grade A0 (9 alarm threshold points), room temperature tensile strength 3240 MPa, high temperature tensile strength at 1200℃ 1236 MPa, withstand current >12A, and cutting area 310,000 mm². 2 Cutting time: 43.9 hours; Cutting efficiency: 0.70615 million mm. 2 / h.

[0032] Example 4 The difference between this embodiment and Embodiment 1 is that: an alloy molybdenum wire for wire cutting includes the following components: molybdenum powder, niobium powder and WC-modified Al-Mg-Nb powder with a purity of 99.7%; the particle size of lanthanum oxide and niobium powder is 2.0 μm. The weight ratio of Al powder, Mg powder, Nb powder, and Sc powder in Al-Mg-Nb-Sc powder is 77:9.6:0.08:0.06. The lanthanum oxide doping amount is 0.82 wt% of the weight of molybdenum powder, the niobium powder doping amount is 5 wt% of the weight of molybdenum powder, and the WC-modified Al-Mg-Nb powder doping amount is 1.0 wt% of the weight of molybdenum powder.

[0033] The finished molybdenum wire prepared in this embodiment has the following properties: crack grade A0 (9 alarm threshold points), room temperature tensile strength 3240 MPa, high temperature tensile strength at 1200℃ 1236 MPa, withstand current >12A, and cutting area 310,000 mm². 2 Cutting time: 43.9 hours; Cutting efficiency: 0.70615 million mm. 2 / h.

[0034] Example 5 The difference between this embodiment and Embodiment 1 is that: an alloy molybdenum wire for wire cutting includes the following components: molybdenum powder, tantalum powder and WC-modified Al-Mg-Nb powder with a purity of 99.7%; the particle size of lanthanum oxide and tantalum powder is 3.2 μm. The weight ratio of Al powder, Mg powder, Nb powder, and Sc powder in Al-Mg-Nb-Sc powder is 87:9.4:0.09:0.04. The lanthanum oxide doping amount is 0.82 wt% of the weight of molybdenum powder, the tantalum powder doping amount is 5 wt% of the weight of molybdenum powder, and the WC-modified Al-Mg-Nb powder doping amount is 0.8 wt% of the weight of molybdenum powder.

[0035] The finished molybdenum wire prepared in this embodiment has the following properties: crack grade A0 (7 alarm threshold points), room temperature tensile strength 3086 MPa, high temperature tensile strength at 1200℃ 1029 MPa, withstand current >12A, and cutting area 280,000 mm². 2 Cutting time: 42.6 hours; Cutting efficiency: 0.65728 million mm. 2 / h.

[0036] Example 6 The difference between this embodiment and Embodiment 1 is that: an alloy molybdenum wire for wire cutting includes the following components: molybdenum powder, vanadium powder and WC-modified Al-Mg-Nb powder with a purity of 99.6%; the particle size of lanthanum oxide and tantalum powder is 2.8 μm. The weight ratio of Al powder, Mg powder, Nb powder, and Sc powder in Al-Mg-Nb-Sc powder is 83:9.7:0.07:0.03. The lanthanum oxide doping amount is 0.85 wt% of the weight of molybdenum powder, the tantalum powder doping amount is 15 wt% of the weight of molybdenum powder, and the WC-modified Al-Mg-Nb powder doping amount is 0.6 wt% of the weight of molybdenum powder.

[0037] The finished molybdenum wire prepared in this embodiment has the following properties: crack grade A1 (80 alarm threshold points), room temperature tensile strength 3310 MPa, high temperature tensile strength at 1200℃ 1048 MPa, withstand current >12A, and cutting area 340,000 mm². 2 Cutting time: 43.8 hours; Cutting efficiency: 0.77626 million mm. 2 / h.

[0038] Example 7 The difference between this embodiment and Embodiment 1 is that: an alloy molybdenum wire for wire cutting includes the following components: molybdenum powder, rhenium powder and WC-modified Al-Mg-Nb powder with a purity of 99.8%; the particle size of lanthanum oxide and tantalum powder is 2.3 μm. The weight ratio of Al powder, Mg powder, Nb powder, and Sc powder in Al-Mg-Nb-Sc powder is 85:9.6:0.05:0.05. The lanthanum oxide doping amount is 0.88 wt% of the weight of molybdenum powder, the rhenium powder doping amount is 15 wt% of the weight of molybdenum powder, and the WC-modified Al-Mg-Nb powder doping amount is 0.85 wt% of the weight of molybdenum powder.

[0039] The finished molybdenum wire prepared in this embodiment has the following properties: crack grade A0 (6 alarm threshold points), room temperature tensile strength 3159 MPa, high temperature tensile strength at 1200℃ 1075 MPa, withstand current >12A, and cutting area 335,000 mm². 2Cutting time: 44.3 hours; Cutting efficiency: 0.75621 million mm. 2 / h.

[0040] Comparative Example 1 The difference between this comparative example and Example 1 is that it does not contain metal powder and WC-modified Al-Mg-Nb powder, and the total lanthanum oxide content is 5000 ppm.

[0041] The finished molybdenum wire prepared in this comparative example has the following properties: crack grade C (1200 alarm threshold points), room temperature tensile strength 2189MPa, high temperature tensile strength at 1200℃ 649MPa, withstand current none (wire breakage during processing), wire breakage at cutting area, cutting time none, and cutting efficiency none.

[0042] Comparative Example 2 The difference between this comparative example and Example 1 is that it does not contain WC-modified Al-Mg-Nb powder.

[0043] The finished molybdenum wire prepared in this comparative example has the following properties: crack grade A2 (190 alarm threshold points), room temperature tensile strength 2364 MPa, high temperature tensile strength at 1200℃ 725 MPa, withstand current 5.5 A, and cutting area 200,000 mm². 2 Cutting time: 50 hours; Cutting efficiency: 0.44098 million mm. 2 / h.

[0044] Comparative Example 3 The difference between this comparative example and Example 1 is that Al-Mg-Nb powder is used instead of WC-modified Al-Mg-Nb powder.

[0045] The finished molybdenum wire prepared in this comparative example has the following properties: crack grade A2 (220 alarm threshold points), room temperature tensile strength 2423 MPa, high temperature tensile strength at 1200℃ 751 MPa, withstand current 5A, and cutting area 230,000 mm². 2 Cutting time: 51 hours; Cutting efficiency: 0.45098 million mm. 2 / h.

[0046] Therefore, it can be seen that all embodiments 1 to 7 of the present invention use rare earth oxides, metal powders, and WC-modified Al-Mg-Nb-Sc powder to dope high-purity molybdenum powder, with rare earth oxide doping amount of 0.7~1.1wt%, metal powder doping amount of 5~15wt%, and WC-modified Al-Mg-Nb powder doping amount of 0.5~1.5wt%. Designed for the processing requirements of 250mm thick workpieces, the cutting stability and efficiency are better, and the crack level control is more stringent (A0~A2 level, 15% alarm threshold number <200). The synergistic effect of several components achieves a balance between the strength and crack resistance of the molybdenum alloy, and improves the high-temperature creep resistance and crack resistance of the molybdenum alloy. In Comparative Example 1, the doping amount of rare earth oxides was extremely low, and it did not contain metal powder or WC-modified Al-Mg-Nb powder, resulting in poor strength and high-temperature stability of the finished molybdenum wire. In Comparative Example 2, although it contained rare earth oxides and metal powder, which improved the tensile strength and high-temperature stability of the alloy molybdenum wire to some extent compared to Comparative Example 1, it still lacked WC-modified Al-Mg-Nb powder, and its overall tensile strength and high-temperature stability were still significantly inferior to those of Example 1. This was mainly due to the pinning grain boundary effect of the WC-modified Al-Mg-Nb-Sc powder, which improved the thermal stability of the material and thus enhanced the high-temperature creep resistance and crack resistance of the molybdenum alloy. In Comparative Example 3, there was a certain improvement compared to Comparative Example 2, mainly due to the effect of Al-Mg-Nb powder. However, since the Al-Mg-Nb powder was not modified, its overall tensile strength and high-temperature stability were still somewhat inferior to those of Example 1. This sufficiently demonstrates that the synergistic effect of the additives in this example significantly contributes to the improvement of the strength, high-temperature stability, and crack resistance of the molybdenum powder.

[0047] The above are merely preferred embodiments of the present invention and are not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A molybdenum alloy wire for wire EDM, characterized in that, It comprises the following components: molybdenum powder and additives, wherein the additives include rare earth oxides, metal powders and WC-modified Al-Mg-Nb powder; the doping amount of the rare earth oxides is 0.7~1.1 wt% of the weight of the molybdenum powder, the doping amount of the metal powder is 5~15 wt% of the weight of the molybdenum powder, and the doping amount of the WC-modified Al-Mg-Nb powder is 0.5~1.5 wt% of the weight of the molybdenum powder.

2. The alloy molybdenum wire for wire cutting according to claim 1, characterized in that, The doping amount of the rare earth oxide is 0.7~0.9 wt% of the weight of the molybdenum powder; the doping amount of the metal powder is 10~15 wt% of the weight of the molybdenum powder; and the doping amount of the WC-modified Al-Mg-Nb powder is 0.5~1.0 wt% of the weight of the molybdenum powder.

3. The alloy molybdenum wire for wire cutting according to claim 1, characterized in that, The weight ratio of Al powder, Mg powder, Nb powder and Sc powder in the Al-Mg-Nb-Sc powder is 70-90: 9-10: 0.01-0.1: 0.01-0.

1.

4. The alloy molybdenum wire for wire cutting according to claim 1, characterized in that, The preparation method of the WC-modified Al-Mg-Nb-Sc powder is as follows: WC powder is added to Al-Mg-Nb-Sc powder, and the powder is wet-milled for 15-20 hours to ensure that the WC powder is uniformly dispersed in the Al-Mg-Nb-Sc powder. After drying at 70-100℃ for 5-8 hours, WC-modified Al-Mg-Nb-Sc powder material is obtained. The WC powder accounts for 10wt%-20wt% of the Al-Mg-Nb-Sc powder.

5. The method for preparing alloy molybdenum wire for wire cutting according to claim 1, characterized in that, Includes the following steps; Molybdenum powder, rare earth oxides and metal powder are doped to prepare a uniform powder, which is then isostatically pressed, pre-sintered, and then sintered again after adding WC-modified Al-Mg-Nb-Sc powder. After furnace cooling, a molybdenum alloy billet is obtained. The sintered molybdenum alloy billet is hot-rolled into molybdenum wire rods. The molybdenum wire rod is then subjected to at least one rotary forging, at least one hot drawing process, at least one annealing, and high-speed cold drawing to obtain the alloy molybdenum wire for wire cutting.

6. The method for preparing alloy molybdenum wire for wire cutting according to claim 5, characterized in that, During pre-sintering: the pressed compact is placed in a hydrogen atmosphere sintering furnace, heated to 1830~2100℃, held for 4~6 hours, and cooled with the furnace to obtain a density of 9.6~9.9 g / cm³. 3 The pre-sintered material.

7. The method for preparing alloy molybdenum wire for wire cutting according to claim 5, characterized in that, During re-sintering: WC-modified Al-Mg-Nb-Sc powder is added to the pre-sintered material, and sintering is continued under a hydrogen atmosphere to obtain molybdenum alloy billets.

8. The method for preparing alloy molybdenum wire for wire cutting according to claim 5, characterized in that, During hot continuous rolling: the rolling temperature is 1400~1500℃, and the final rolling speed is 10~15m / s; During rotary forging: the forging temperature is 1300~1500℃, the speed is 3~4m / min, and the deformation per pass is 15%~30%.

9. The method for preparing alloy molybdenum wire for wire cutting according to claim 5, characterized in that, The hot drawing process includes a coarse specification stage and a fine specification stage; the coarse specification stage is heated by a 1-2m long heating zone at a temperature of 700-900℃ and a speed of 2-10m / min; the fine specification stage adopts multi-die string drawing at a speed of 20-50m / min and a deformation of 20-30% per hot drawing pass.

10. The method for preparing alloy molybdenum wire for wire cutting according to claim 5, characterized in that, During high-speed cold drawing: Before cold drawing, coat the surface of the filament with a specific gravity of 1.0~1.05 g / cm³. 3 The graphite emulsion is dried, and the cold drawing temperature is room temperature. The drawing speed is 150~400m / min, and the deformation per cold drawing pass is 10~20%, finally producing the finished molybdenum wire.

Images