Molybdenum alloy part, preparation method and application

Abstract

The invention provides a molybdenum alloy part, a preparation method and application, and belongs to the field of alloy smelting. The sintered blank is rolled by a gradient rolling ratio distributed from large to small and a gradient rolling temperature distributed from large to small. The first several times of large rolling ratio rapid cogging, primary grain refinement, further uniform deformation, dynamic recrystallization promotion, initial high temperature, substantial reduction of deformation resistance of molybdenum and inhibition of crack propagation, and the second several times of small rolling ratio optimization of structure uniformity, alleviation of processing difficulty caused by large hardness and poor plasticity, reduction of crack generation probability and reduction of residual stress are realized; local stress concentration is reduced, and the fatigue life is prolonged. A fine and uniform recrystallization structure is formed through the rolling synergistic effect of the gradient rolling ratio distributed from large to small and the gradient rolling temperature, the material strength, toughness and anti-fatigue performance are improved, and the service life of the melt-spinning wheel is prolonged.

Description

Technical Field

[0001] The present invention belongs to the field of alloy smelting, and particularly relates to a molybdenum alloy part, a preparation method and an application thereof. Background Art

[0002] The spinning wheel is a key component applied to a spinning machine, and is used for spinning molten metal to produce amorphous and nanocrystalline alloys. During the operation of the spinning machine, in a working environment of 1400 - 1700 °C, high-quality amorphous ribbons and NdFeB materials are prepared through efficient heat conduction. The spinning wheel is in a long-term periodic cold and heat conversion, and it must have good heat conduction performance and thermal fatigue resistance.

[0003] At present, ordinary spinning wheels mostly adopt copper-based materials, mostly chromium zirconium copper or alumina-dispersed copper materials. The hardness of the copper wheel is generally HB110 - 130, the average grain size is 80 - 120 μm, and the softening temperature ≤ 1000 °C; while the hardness of the molybdenum wheel is generally HV≥200, the average grain size is 10 - 100 μm, and the softening temperature is 1300 - 1600 °C. The molybdenum wheel has higher hardness and higher softening temperature than the copper wheel. When used in the production of NdFeB amorphous ribbons, the molybdenum spinning wheel has better performance and life advantages. However, the preparation technology of the molybdenum spinning wheel is difficult, mainly because its finished product size is large and the performance requirements are high. A reasonable process is required during preparation to achieve the purpose of obtaining a finished product with a suitable size and meeting the performance requirements.

[0004] Therefore, there is an urgent need to develop a molybdenum spinning wheel product and a preparation method with excellent performance, long life, stable preparation process and appropriate preparation cost. Summary of the Invention

[0005] According to the technical problems existing in the prior art, the present invention provides a molybdenum alloy part, a preparation method and an application thereof.

[0006] One of the purposes of the present invention is to provide a preparation method of a molybdenum alloy part, including: Obtaining a sintered billet; Performing multi-stage rolling on the sintered billet, wherein the rolling ratio is controlled in a gradually decreasing manner, and the total rolling ratio is 25 - 80%; the total rolling ratio is the sum of the rolling ratios of each stage; Implementing gradient temperature control synchronously in each rolling stage, adjusting the rolling temperature in a gradually decreasing manner, the initial rolling temperature is 1400 - 1600 °C, the gradient of the rolling temperature is 50 - 100 °C, and the lowest rolling temperature is not lower than 1300 °C; Then obtaining the molybdenum alloy part through annealing and machining.

[0007] During rolling, two oxyacetylene torches are used to heat the ring part to prevent cracking due to low temperature deformation or inability to perform rolling due to excessive rolling force during the rolling process.

[0008] Preferably, the feed per revolution is 0.5 - 10 mm.

[0009] Preferably, the number of rolling stages is 4 - 8 stages, and the rolling ratio for each stage of rolling is 2 - 25%.

[0010] Preferably, obtaining the sintered blank includes powder mixing, pressing into shape, sizing and sintering to obtain the sintered blank.

[0011] Preferably, the powder mixing includes mixing molybdenum powder, titanium hydride powder, zirconium hydride powder and carbon powder; The average particle size of the molybdenum powder is 3.0 - 3.5 μm; The particle size distributions D100 of the titanium hydride powder and the zirconium hydride powder are both ≤ 30 μm; The particle size of the carbon powder is 0.1 μm.

[0012] Preferably, the pressing into shape is cold isostatic pressing treatment, the pressure of the cold isostatic pressing treatment is 160 - 200 MPa, and the pressure holding time is 10 - 30 min.

[0013] Preferably, the sintering is carried out under hydrogen with a flow rate of 15 - 60 m 3 / h or under vacuum.

[0014] Preferably, the sintering temperature is 1900 - 2200 °C, and the heating rate is 40 - 100 °C / h.

[0015] Preferably, during the heating process of the sintering, when heating to the first holding temperature, the second holding temperature, the third holding temperature, the fourth holding temperature, the fifth holding temperature and the sixth holding temperature respectively, each is held for 1 - 8 h; The first holding temperature is 620 - 680 °C, the second holding temperature is 800 - 900 °C; the third holding temperature is 1200 °C; the fourth holding temperature is 1400 °C; the fifth holding temperature is 1600 °C; the sixth holding temperature is 1800 °C.

[0016] The second object of the present invention is to provide a molybdenum alloy part prepared by the preparation method as described above.

[0017] The third object of the present invention is to provide an application of the molybdenum alloy part as described above in the preparation of amorphous ribbons and NdFeB materials.

[0018] The beneficial effects of the present invention: The present invention controls the rolling ratio in a decreasing manner stage by stage for the sintered billet, with the total rolling ratio being 25 - 80%; the total rolling ratio is the sum of the rolling ratios of each stage; gradient temperature control is synchronously implemented in each rolling stage, the rolling temperature is adjusted in a decreasing manner stage by stage, the initial rolling temperature is 1400 - 1600 °C, the gradient of the rolling temperature is 50 - 100 °C, and the lowest rolling temperature is not lower than 1300 °C; then roll the sintered billet. In the first few stages, a large rolling ratio is used to quickly open the billet, initially refine the grains, further uniformly deform, and promote dynamic recrystallization. In the later stages, a small rolling ratio is used to optimize the tissue uniformity, relieve the processing difficulties caused by high hardness and poor plasticity, reduce the probability of crack generation, reduce residual stress, reduce local stress concentration, and improve the fatigue life. The initial high temperature greatly reduces the deformation resistance of molybdenum, enhances plasticity, makes it easier to perform large-deformation billet opening, reduces equipment load and tool wear. At high temperatures, the atomic diffusion ability is enhanced, promoting defect repair and inhibiting crack propagation. Subsequently, the temperature is gradually decreased to ensure the continuous progress of dynamic recrystallization, refine the grains and eliminate work hardening. At the same time, the decreasing temperature avoids overheating of the material, reduces the oxidation risk, and reduces the tissue inhomogeneity caused by thermal stress.

[0019] The combined action of the rolling ratio decreasing stage by stage and the rolling with the rolling temperature decreasing stage by stage forms a fine and uniform recrystallized structure, improving the strength, toughness and fatigue resistance of the material and extending the service life of the spinning wheel. Detailed implementation mode

[0020] According to the first aspect of the present invention, a method for preparing a molybdenum alloy part is provided, including: Obtain a sintered billet; Perform multi-stage rolling on the sintered billet, wherein the rolling ratio is controlled in a decreasing manner stage by stage, and the total rolling ratio is 25 - 80%; the total rolling ratio is the sum of the rolling ratios of each stage; Synchronously implement gradient temperature control in each rolling stage, adjust the rolling temperature in a decreasing manner stage by stage, the initial rolling temperature is 1400 - 1600 °C, the gradient of the rolling temperature is 50 - 100 °C, and the lowest rolling temperature is not lower than 1300 °C; Then obtain the molybdenum alloy part through annealing and machining.

[0021] During rolling, two oxyacetylene torches are used to heat the ring piece to prevent cracking due to low temperature during rolling or inability to roll due to excessive rolling force.

[0022] In the present invention, in the first stage, a large rolling ratio causes severe plastic deformation, such as dislocation multiplication and grain boundary slip, breaking the original coarse grains and forming a fine-grained structure, with the grain size reduced to the micron level. Grain refinement significantly improves the yield strength and hardness of the material, while enhancing the fatigue resistance.

[0023] At the initial high temperature, the atomic diffusion capacity of the molybdenum alloy is enhanced, the activation energy of dislocation movement is reduced, and the plasticity of the material is significantly improved. At this time, a large rolling ratio is used to quickly close the residual pores inside the sintered billet through severe plastic deformation, eliminate internal defects of the material, and improve density.

[0024] High rolling ratio combined with thermal activation conditions of 1400~1600℃ promotes dynamic recrystallization (DRX). New fine equiaxed crystals replace deformed grains, eliminate dislocation entanglement caused by work hardening, reduce local stress concentration, thereby inhibiting crack initiation and improving material toughness. Reducing the rolling ratio in the later stage gradually corrects dimensional deviations through small plastic deformation, avoids the rebound effect caused by large deformation, reduces turning allowance, and improves yield rate.

[0025] The rolling temperature is 1300~1600℃, which ensures continuous dynamic recrystallization and avoids mixed crystal structure caused by incomplete recrystallization. The strength difference in the mixed crystal zone reaches 15%-20%, which improves the uniformity of the structure.

[0026] In the present invention, the total rolling ratio cannot be less than 25%. If it is less than 25%, the density of the molybdenum alloy part will be insufficient, splashing will be easily generated during use, and the part will not be able to work normally.

[0027] In a preferred embodiment of the present invention, the feed amount per revolution is 0.5-10 mm.

[0028] In the present invention, the feed rate per revolution cannot be too high, otherwise it will cause excessive rolling force and damage the rolling mill; it cannot be too small, otherwise it will lead to failure to achieve the minimum feed rate for plastic forging, resulting in uneven density inside and outside, or delamination and cracking.

[0029] In a preferred embodiment of the present invention, the number of rolling stages is 4 to 8 stages, and the rolling ratio of each stage is 2 to 25%.

[0030] In a preferred embodiment of the present invention, the number of rolling stages is 6 stages, and the gradient rolling ratio distribution from large to small is: Stage 1: rolling ratio 15%-25%; Stage 2: rolling ratio 15%-24%; Stage 3: rolling ratio 12%-19%; Stage 4: rolling ratio 5%-12%; Stage 5: rolling ratio 3%-8%; Stage 6: rolling ratio 2%-5%.

[0031] The rolling temperature distribution method that decreases step by step is: Stage 1: 1550~1600℃; The second stage: 1500 - 1550 °C; The third stage: 1450 - 1550 °C; The fourth stage: 1400 - 1450 °C; The fifth stage: 1350 - 1400 °C; The sixth stage: 1300 - 1350 °C.

[0032] In a preferred embodiment of the present invention, a radial - axial ring rolling mill is used for rolling.

[0033] In a preferred embodiment of the present invention, obtaining the sintered blank includes powder mixing, cold isostatic pressing, sizing and sintering to obtain the sintered blank.

[0034] In a preferred embodiment of the present invention, powder mixing includes mixing molybdenum powder, titanium hydride powder, zirconium hydride powder and carbon powder; The average particle size of the molybdenum powder is 3.0 - 3.5 μm; The particle size distributions D100 of the titanium hydride powder and the zirconium hydride powder are both ≤ 30 μm; The particle size of the carbon powder is 0.1 μm.

[0035] In the present invention, the doped raw material powder with fine particles reduces the size of the carbide dispersion phase, thereby enhancing the dispersion strengthening effect and improving the tensile properties.

[0036] In a preferred embodiment of the present invention, cold isostatic pressing is used for cold isostatic pressing treatment, the pressure of the cold isostatic pressing treatment is 160 - 200 MPa, and the pressure - holding time is 10 - 30 min.

[0037] In the present invention, isostatic pressing is used to directly form a ring - shaped blank, thereby reducing the powder consumption of the solid material. The pressure of the cold isostatic pressing treatment is, for example, 160 MPa, 165 MPa, 170 MPa, 180 MPa, 190 MPa, 195 MPa or 200 MPa, and the pressure - holding time is, for example, 10 min, 15 min, 20 min, 25 min or 30 min.

[0038] In a preferred embodiment of the present invention, sintering is carried out under hydrogen with a flow rate of 15 - 60 m 3 / h In the present invention, hydrogen with a flow rate of 15 - 60 m 3 / h can more effectively promote the removal of impurities and increase the density.

[0039] In a preferred embodiment of the present invention, the sintering temperature is 1900 - 2200 °C, and the heating rate is 40 - 100 °C / h.

[0040] In the present invention, if the sintering temperature is too low, the density of the sintered blank may not meet the requirements; if the sintering temperature is too high, over-sintering may occur, resulting in a decrease in tensile properties. In a preferred embodiment of the present invention, during the heating-up process of sintering, when the temperature is raised to the first holding temperature, the second holding temperature, the third holding temperature, the fourth holding temperature, the fifth holding temperature, and the sixth holding temperature respectively, each is held for 1 - 8 h. The first holding temperature is 620 - 680 °C, the second holding temperature is 800 - 900 °C; the third holding temperature is 1200 °C; the fourth holding temperature is 1400 °C; the fifth holding temperature is 1600 °C; the sixth holding temperature is 1800 °C.

[0041] In the present invention, if the holding time is too short, the internal and external densities and grain sizes of the sintered blank may be uneven, easily leading to cracking during blooming; if the holding time is too long, over-sintering may occur, resulting in a decrease in tensile properties.

[0042] In the present invention, the holding at the first holding temperature and the second temperature is because titanium hydride and zirconium hydride mainly decompose rapidly in the corresponding temperature ranges, and a large amount of gas is generated during decomposition. To prevent invisible defects from being generated in the blank due to the external discharge of gas, a holding section is added in these two temperature ranges; the holding in the range from the third holding temperature to the sixth holding temperature is to better remove impurities such as O, K, Cl, Al, Na, Mg, Ca, Fe, etc., and make the internal and external temperatures of the sintered blank uniform, improving the performance of the sintered blank.

[0043] In a preferred embodiment of the present invention, sintering is carried out using an intermediate frequency induction heating furnace.

[0044] In a preferred embodiment of the present invention, stress relief annealing is used for annealing, and the temperature is 1100 - 1300 °C. When the annealing temperature is low, due to insufficient annealing, cracking may occur during use due to large thermal stress, and then the metal melt splashes, resulting in the termination of use; when the annealing temperature is too high, the strength decreases, and the metal melt also splashes, resulting in the termination of use.

[0045] In a preferred embodiment of the present invention, during rolling, two oxyacetylene flame guns are used to heat the ring blank to prevent cracking due to low temperature deformation or inability to roll due to excessive rolling force during the rolling process.

[0046] According to the second aspect of the present invention, there is provided a molybdenum alloy part prepared by the preparation method as described above.

[0047] According to the third aspect of the present invention, there is provided an application of the molybdenum alloy part as described above in the preparation of amorphous ribbons and NdFeB materials.

[0048] In the present invention, the application of the molybdenum alloy part as a molybdenum spinning wheel in the preparation of amorphous ribbons and NdFeB materials.

[0049] Example 1 In this example, a molybdenum spin casting wheel is prepared with a finished product size of D560*d480*h130mm. The specific steps are as follows: (1) Mix molybdenum powder with a particle size of 3.2μm, titanium hydride powder with D100 of 20um, zirconium hydride powder with D100 of 20um, and carbon powder with a particle size of 0.1um for 24h to obtain alloy powder; (2) Load the mixed powder into a cold isostatic pressing mold for cold isostatic pressing. The pressure of cold isostatic pressing is 180MPa, and the pressure holding time is 10min. And shape it according to the shaping drawing; (3) Sinter the green compact obtained in step (2) with an intermediate frequency induction heating furnace; the sintering is carried out in a hydrogen atmosphere with a hydrogen flow rate of 50m 3 / h. The heating rate in the whole temperature range is 60℃ / h, and it is held for 2h at 650℃, 850℃, 1200℃, 1400℃, 1600℃, and 1800℃ respectively; the sintering temperature is 2150℃, and the holding time is 6h to obtain a sintered compact with a size of D356*d156*135mm; (4) Roll the sintered compact obtained in step (3), and the feed per revolution is 0.5 - 10mm; keep 2 oxyacetylene flame torches for supplementary heating during rolling; roll in 6 stages, and the gradually decreasing rolling ratio distribution method is: The first stage: rolling ratio 20%; The second stage: rolling ratio 18%; The third stage: rolling ratio 15%; The fourth stage: rolling ratio 5%; The fifth stage: rolling ratio 3%; The sixth stage: rolling ratio 2%; The gradually decreasing rolling temperature distribution method is: The first stage: 1550 - 1600℃; The second stage: 1500 - 1550℃; The third stage: 1450 - 1550℃; The fourth stage: 1400 - 1450℃; The fifth stage: 1350 - 1400℃; The sixth stage: 1300 - 1350℃; After rolling, a semi-finished product of the spin casting wheel is obtained; (5) Carry out stress relief annealing treatment on the sintered compact obtained in step (4), with an annealing temperature of 1280℃ and a holding time of 2h.

[0050] (6) Process the semi-finished product obtained in step (5) into a finished product according to the drawing.

[0051] For the molybdenum sputtering wheel prepared by the method of this embodiment, the average actual density measured by the hydrostatic weighing method is 10.18 g / cm 3 ; the average hardness is 270 HV30, and the service life is 1.0 year.

[0052] Example 2 This embodiment prepares a molybdenum sputtering wheel with finished product dimensions of D560*d480*h130 mm. The specific steps are as follows: (1) Mix molybdenum powder with a particle size of 3.2 μm, titanium hydride powder with D100 of 20 μm, zirconium hydride powder with D100 of 20 μm, and carbon powder with a particle size of 0.1 μm for 24 h to obtain alloy powder; (2) Load the mixed powder into a cold isostatic pressing mold for cold isostatic pressing. The pressure of cold isostatic pressing is 180 MPa, and the pressure holding time is 10 min. And perform shaping according to the shaping drawing; (3) Sinter the green compact obtained in step (2) using an intermediate frequency induction heating furnace; the sintering is carried out in a hydrogen atmosphere with a hydrogen flow rate of 50 m 3 / h, the heating rate in the entire temperature range is 70 °C / h, and keep warm for 2 h at 650 °C, 850 °C, 1200 °C, 1400 °C, 1600 °C, and 1800 °C respectively; the sintering temperature is 2150 °C, and the holding time is 6 h to obtain a sintered compact. The size of the sintered compact is D326*d63*135 mm; (4) Roll the sintered compact obtained in step (3), and the feed per revolution is 0.5 - 10 mm; keep 2 oxyacetylene flame torches for supplementary heating during rolling; roll in 6 stages, and the gradient rolling ratio distribution method from large to small is: The 1st stage: rolling ratio 25%; The 2nd stage: rolling ratio 24%; The 3rd stage: rolling ratio 18%; The 4th stage: rolling ratio 12%; The 5th stage: rolling ratio 6%; The 6th stage: rolling ratio 2%; The gradient rolling temperature distribution method from large to small is: The 1st stage: 1550 - 1600 °C; The 2nd stage: 1500 - 1550 °C; The 3rd stage: 1450 - 1550 °C; The 4th stage: 1400 - 1450 °C; The 5th stage: 1350 - 1400 °C; The 6th stage: 1300 - 1350 °C; After rolling, a semi-finished product of the spinning wheel is obtained; (5) The sintered blank obtained in step (4) is subjected to stress relief annealing treatment, the annealing temperature is 1280 °C, and the holding time is 2 h.

[0053] (6) The semi-finished product obtained in step (5) is processed into a finished product according to the drawing.

[0054] For the molybdenum spinning wheel prepared by the method of this embodiment, the average actual density measured by the hydrostatic weighing method is 10.19 g / cm 3 ; the average hardness is 273 HV30, and the service life is 1.1 years.

[0055] Comparative Example 1 The difference from Example 1 is that it is in the sintered state of pure molybdenum, with lower density and lower hardness. The specific steps are as follows: (1) Molybdenum powder with a particle size of 3.2 μm.

[0056] (2) The powder is loaded into a cold isostatic pressing mold for cold isostatic pressing treatment. The pressure of cold isostatic pressing is 200 MPa, and the pressure holding time is 10 min. And shaping is carried out according to the shaping drawing.

[0057] (3) The blank obtained in step (2) is sintered with an intermediate frequency induction heating furnace; the sintering is carried out in a hydrogen atmosphere, and the hydrogen flow rate is 50 m 3 / h, the heating rate in the whole temperature range is 60 °C / h, and it is held for 2 h at 650 °C, 850 °C, 1200 °C, 1400 °C, 1600 °C, and 1800 °C; the sintering temperature is 2150 °C, and the holding time is 6 h to obtain a sintered blank.

[0058] (4) The semi-finished product obtained in step (3) is processed into a finished product according to the drawing.

[0059] For the 2 pure molybdenum spinning wheels prepared by the method of this comparative example, the average actual density measured by the hydrostatic weighing method is 10.05 g / cm 3 ; the average hardness is 160 HV30, and splashing occurs during use, which is unqualified.

[0060] Comparative Example 2 This example prepares a molybdenum spinning wheel with a finished product size of D560*d480*h130 mm. The difference from Example 1 is that the rolling deformation amount is too small and the hardness after rolling is insufficient. The specific steps are as follows: (1) Mix molybdenum powder with a particle size of 3.2 μm with titanium hydride powder with D100 of 20 um, zirconium hydride powder with D100 of 20 um, and carbon powder with a particle size of 0.1 um for 24 h to obtain an alloy powder; (2) Load the mixed powder into a cold isostatic pressing mold for cold isostatic pressing. The pressure of cold isostatic pressing is 180 MPa, and the pressure holding time is 10 min. Then shape it according to the sizing drawing; (3) Sinter the green compact obtained in step (2) using an intermediate frequency induction heating furnace; The sintering is carried out in a hydrogen atmosphere with a hydrogen flow rate of 50 m 3 / h. The heating rate in the whole temperature range is 60 °C / h. Hold for 2 h at 650 °C, 850 °C, 1200 °C, 1400 °C, 1600 °C, and 1800 °C respectively; The sintering temperature is 2150 °C, and the holding time is 6 h to obtain a sintered compact. The size of the sintered compact is D472*347*135 mm; (4) Roll the sintered compact obtained in step (3). The total rolling ratio is 22%, and the feed per revolution is 0.5 - 10 mm; During rolling, maintain 2 oxyacetylene flame torches for supplementary heating; Roll in 2 stages. The gradient rolling ratio distribution method from large to small is as follows: The first stage: The rolling ratio is 12%; The second stage: The rolling ratio is 10%; The gradient rolling temperature distribution method from large to small is as follows: The first stage: 1550 - 1600 °C; The second stage: 1500 - 1550 °C; After rolling, obtain a semi-finished product of a spinning wheel; (5) Perform stress relief annealing on the sintered compact obtained in step (4). The annealing temperature is 1280 °C, and the holding time is 2 h.

[0061] (6) Process the semi-finished product obtained in step (5) according to the drawing to obtain the finished product.

[0062] For the molybdenum spinning wheel prepared by the method of this example, the average actual density measured by the hydrostatic weighing method is 10.02 g / cm 3 ; The average hardness is 200 HV30. Severe splashing occurs during use, and it is unqualified.

[0063] Comparative Example 3 In this example, a molybdenum spinning wheel is prepared. The finished product size is D560*d480*h130 mm. Different from Example 1, the rolling temperature is always too high, and the hardness after rolling is low. The specific steps are as follows: (1) Mix molybdenum powder with a particle size of 3.2 μm, titanium hydride powder with D100 of 20 μm, zirconium hydride powder with D100 of 20 μm, and carbon powder with a particle size of 0.1 μm for 24 h to obtain an alloy powder; (2) Load the mixed powder into a cold isostatic pressing mold for cold isostatic pressing. The pressure of cold isostatic pressing is 180 MPa, and the pressure holding time is 10 min. Then perform sizing according to the sizing drawing; (3) Sinter the green compact obtained in step (2) using an intermediate frequency induction heating furnace; the sintering is carried out in a hydrogen atmosphere with a hydrogen flow rate of 50 m 3 / h. The heating rate in the entire temperature range is 60 °C / h, and it is held for 2 h at 650 °C, 850 °C, 1200 °C, 1400 °C, 1600 °C, and 1800 °C; the sintering temperature is 2150 °C, and the holding time is 6 h to obtain a sintered compact. The size of the sintered compact is D356*156*135 mm; (4) Roll the sintered compact obtained in step (3). The feed per revolution is 0.5 - 10 mm; during rolling, keep 2 oxyacetylene flame torches for supplementary heating; roll in 6 stages, and the gradient rolling ratio distribution method from large to small is: The 1st stage: rolling ratio 20%; The 2nd stage: rolling ratio 18%; The 3rd stage: rolling ratio 15%; The 4th stage: rolling ratio 5%; The 5th stage: rolling ratio 3%; The 6th stage: rolling ratio 2%; The rolling temperature distribution method is: The 1st stage: 1550 - 1600 °C; The 2nd stage: 1550 - 1600 °C; The 3rd stage: 1550 - 1600 °C; The 4th stage: 1550 - 1600 °C; The 5th stage: 1550 - 1600 °C; The 6th stage: 1550 - 1600 °C; After rolling, obtain a semi-finished product of a spinning wheel; (5) Perform stress relief annealing on the sintered compact obtained in step (4). The annealing temperature is 1280 °C, and the holding time is 2 h.

[0064] (6) Process the semi-finished product obtained in step (5) into a finished product according to the drawing.

[0065] For the molybdenum spinning wheel prepared by the method of this embodiment, the average actual density measured by the hydrostatic weighing method is 10.18 g / cm 3 ; the average hardness is 200 HV30, and the service life is 2 days, which is unqualified.

[0066] Comparative Example 4 In this embodiment, a molybdenum spinning wheel is prepared. The finished product size is D560*d480*h130mm. Different from Embodiment 1, the rolling compression ratio has been too large, and severe delamination occurs after rolling. The specific steps are as follows: (1) Mix molybdenum powder with a particle size of 3.2μm, titanium hydride powder with D100 of 20um, zirconium hydride powder with D100 of 20um, and carbon powder with a particle size of 0.1um for 24h to obtain alloy powder; (2) Load the mixed powder into a cold isostatic pressing mold for cold isostatic pressing. The pressure of cold isostatic pressing is 180MPa, and the pressure holding time is 10min. And shape it according to the shaping drawing; (3) Sinter the billet obtained in step (2) with an intermediate frequency induction heating furnace; The sintering is carried out in a hydrogen atmosphere, and the hydrogen flow rate is 50m 3 / h. The heating rate in the whole temperature range is 60℃ / h, and it is kept for 2h at 650℃, 850℃, 1200℃, 1400℃, 1600℃, and 1800℃ respectively; The sintering temperature is 2150℃, and the holding time is 6h to obtain a sintered billet. The size of the sintered billet is D356*156*135mm; (4) Roll the sintered billet obtained in step (3). The total rolling ratio is 50%, and the feed per revolution is 0.5 - 10mm; Keep 2 oxyacetylene flame guns for supplementary heating during rolling; Roll in 3 stages, and the gradient rolling ratio distribution method from large to small is: The first stage: the rolling ratio is 21%; The second stage: the rolling ratio is 21%; The third stage: the rolling ratio is 20%; The gradient rolling temperature distribution method from large to small is: The first stage: 1550~1600℃; The second stage: 1500~1550℃; The third stage: 1450~1550℃; After rolling, a semi-finished product of the spinning wheel is obtained; (5) Perform stress relief annealing on the sintered billet obtained in step (4). The annealing temperature is 1280℃, and the holding time is 2h.

[0067] (6) Process the semi-finished product obtained in step (5) into a finished product according to the drawing.

[0068] For the molybdenum spinning wheel prepared by the method of this embodiment, the average actual density measured by the hydrostatic weighing method is 10.18g / cm 3 ; The average hardness is 270HV30, with delamination, severe splashing after use, and it is unqualified.

Claims

1. A method for preparing a molybdenum alloy part, characterized in that: The preparation method comprises: obtaining a sintered compact; The sintered billet is subjected to multi-stage rolling, wherein the rolling ratio is controlled in a step-by-step decreasing manner, and the total rolling ratio is 25-80%; the total rolling ratio is the sum of the rolling ratios of each stage; Gradient temperature control is implemented synchronously in each rolling stage, and the rolling temperature is adjusted in a step-by-step decreasing manner. The initial rolling temperature is 1400-1600°C, the gradient of the rolling temperature is 50-100°C, and the lowest rolling temperature is not less than 1300°C; After annealing and machining, molybdenum alloy parts are obtained.

2. The preparation method according to claim 1, characterized in that During the rolling process, the feed amount per revolution is 0.5-10 mm.

3. The preparation method according to claim 1, characterized in that: The number of rolling stages is 4 to 8 stages, and the rolling ratio of each stage is 2 to 25%.

4. The preparation method according to claim 1, characterized in that: The obtaining of the sintered compact includes powder mixing, pressing, shaping and sintering to obtain the sintered compact; the mixed powder includes mixed molybdenum powder, titanium hydride powder, zirconium hydride powder and carbon powder; The average particle size of the molybdenum powder is 3.0-3.5 μm; The particle size distribution D100 of the titanium hydride powder and the zirconium hydride powder is both ≤30um; The particle size of the carbon powder is 0.1 um.

5. The preparation method according to claim 4, characterized in that: The pressing and forming is a cold isostatic pressing process; The pressure of the cold isostatic pressing treatment is 160-200 MPa, and the holding time is 10-30 min.

6. The preparation method according to claim 4, characterized in that The sintering is carried out at a flow rate of 15-60 m 3 / h of hydrogen or under vacuum.

7. The preparation method according to claim 4, characterized in that: The sintering temperature is 1900-2200°C, and the heating rate is 40-100°C / h.

8. The preparation method according to claim 7, characterized in that: During the heating process of sintering, when the temperature is raised to the first insulation temperature, the second insulation temperature, the third insulation temperature, the fourth insulation temperature, the fifth insulation temperature and the sixth insulation temperature, the insulation temperature is kept for 1-8 hours respectively; The first insulation temperature is 620-680°C, the second insulation temperature is 800-900°C; the third insulation temperature is 1200°C; the fourth insulation temperature is 1400°C; the fifth insulation temperature is 1600°C; and the sixth insulation temperature is 1800°C.

9. A molybdenum alloy part obtained by the preparation method according to any one of claims 1 to 8.

10. Use of the molybdenum alloy piece according to claim 9 in the preparation of amorphous strips and NdFeB materials.