Treatment method for improving performance stability of same batch of high-specific-gravity tungsten alloy bars

Abstract

The invention belongs to the technical field of powder metallurgy, and discloses a treatment method for improving the performance stability of high-specific-gravity tungsten alloy bars of the same batch. The treatment method comprises the steps that W powder, Ni powder and Fe powder serve as main raw materials, one or more of Mo powder, Re powder, Zr powder and Co powder serve as doping phases, the materials are mixed through a two-section mixing technology and then pressed into a plate blank, the plate blank is subjected to one-step densification and rolling and then machined into a plurality of bar billets, the multiple bar billets are subjected to vacuum annealing, rotary swaging and vacuum heat treatment, and then the high-strength and high-toughness alloy is obtained. And the W-Ni-Fe series high-specific-gravity alloy bar is obtained. According to the treatment method, the stability of the bars in the same batch in the aspects of density and room-temperature mechanical properties can be effectively improved while the high-performance W-Ni-Fe alloy bars are prepared.

Description

Technical Field

[0001] The invention relates to the technical field of powder metallurgy, and in particular to a processing method for improving the performance stability of high-density tungsten alloy rods of the same batch. Background Art

[0002] W-Ni-Fe series high specific gravity tungsten alloy has the advantages of high strength, good plasticity, strong impact toughness and penetration ability, small thermal expansion coefficient, good electrical and thermal conductivity, strong radiation absorption ability, etc. It is widely used in military, aerospace, machinery, atomic energy and other fields. In particular, because W-Ni-Fe series high specific gravity tungsten alloy has 16.5g / cm 3 ~19.0g / cm 3 Its high density makes it an indispensable key material for gyroscope rotors, counterweights, shock absorbers and military projectile cores.

[0003] With the continuous advancement of science and technology, higher requirements are placed on the comprehensive performance of high density tungsten alloy rods: high strength, high toughness, more uniform microstructure, high stability in the same batch, etc. have become indicators for measuring the performance of high density tungsten alloy.

[0004] However, the conventional method for preparing high specific gravity tungsten alloy rods in the prior art is: W, Ni, and Fe powders are mixed in proportion and then pressed into shape, a W-Ni-Fe sintered blank is obtained after sintering, and then a tungsten alloy rod is obtained by forging-heat treatment process. For example, the prior art CN104313377A provides a method of preparing high-performance W-Ni-Fe alloy rods by hot hydrostatic extrusion using W, Ni, and Fe as raw materials after sintering into a rod blank; as in the prior art patent CN108315624A, the tungsten alloy powder raw material is activated by high-energy ball milling, and then a continuous rolling deformation process is used to perform a single-fire large deformation of the tungsten alloy, thereby realizing the preparation of high-performance W-Ni-Fe alloy rods. The above-mentioned preparation methods mainly improve the mechanical properties of W-Ni-Fe alloy rods by preparing high-quality powders, controlling the sintering process, increasing the deformation of the rod blank, etc., but cannot improve the stability of the same batch of high-density tungsten alloy rods, and thus cannot meet the current requirements for the comprehensive performance of high-density tungsten alloy rods, limiting the further application and development of high-density tungsten alloy rods. Summary of the invention

[0005] In order to solve the problem of stability fluctuation in performance of W-Ni-Fe rods in the same batch, the present invention provides a processing method for improving the performance stability of high-density tungsten alloy rods in the same batch. The present invention prepares a slab by sintering first, and after initially increasing the deformation by rolling, the slab is machined into a rod and forged again to further increase the deformation, thereby achieving the preparation of high-performance W-Ni-Fe alloy rods while strictly controlling the stability of the rods in the same batch in terms of density and room temperature mechanical properties.

[0006] A processing method of the present invention for improving the performance stability of high-density tungsten alloy bars of the same batch is achieved by the following technical solutions:

[0007] A processing method for improving the performance stability of high-density tungsten alloy bars of the same batch comprises the following steps:

[0008] Step 1, prepare the slab:

[0009] According to the composition of the W-Ni-Fe high-density tungsten alloy to be upgraded, W powder, Ni powder and Fe powder of corresponding mass are weighed and set aside; the weighed Ni powder and Fe powder are mixed, and then the doping phase powder is added and mixed to obtain a first mixed powder; the weighed W powder is added to the first mixed powder and mixed to obtain a second mixed powder; the second mixed powder is pressed into a blank to obtain a slab.

[0010] It should be noted that the present invention can select the components of the corresponding grades of W-Ni-Fe high-density tungsten alloy rods according to the actual W-Ni-Fe high-density tungsten alloy rods to be upgraded, and weigh the main raw materials of W powder, Ni powder and Fe powder. For example, the W-Ni-Fe high-density tungsten alloy rods targeted by the present invention are W-Ni-Fe high-density tungsten alloy rods with grades of 90W-7Ni-3Fe, 93W-4.9Ni-2.1Fe and 95W-3.5Ni-1.5Fe.

[0011] The present invention uses one or more of Mo powder, Re powder, Zr powder and Co powder as doping phase powder, so as to purify the impurity oxygen elements on the grain boundary by adding the doping phase powder, inhibit the abnormal growth behavior of the grains, effectively enhance the interface bonding force, and help improve the mechanical properties of the W-Ni-Fe alloy.

[0012] The present invention controls the addition amount of the doped phase powder to be ≤1wt% of the total mass of the W powder, the Ni powder and the Fe powder, so as to achieve the same composition range of the existing W-Ni-Fe alloy and significantly enhance the performance on the basis of the existing W-Ni-Fe alloy.

[0013] The present invention takes into account that if the raw materials are directly ball-milled and mixed together, the grinding balls in the tank body will be driven by the high rotation of the ball mill to break the powder, which is easy to introduce impurity elements. Therefore, in order to avoid the introduction of impurity elements during the mixing process, the present invention preferably adopts a two-stage mixing process for mixing, and first mixes Ni powder, Fe powder and doping phase powder, and then adds W powder for mixing, so as to effectively disperse the doping phase in the main raw materials for preparing W-Ni-Fe high-density tungsten alloy rods, thereby achieving uniform distribution of each element in the raw material mixture.

[0014] In some preferred embodiments of the present invention, when preparing the first mixed powder, intermittent dry ball milling is used for preparation. And in some more preferred embodiments of the present invention, during the intermittent dry ball milling, the ball-to-material ratio of each ball milling treatment is 1 to 3:1, the rotation speed is 100 r / min to 200 r / min, the ball milling time of each time is 15 min to 25 min, the interval between two adjacent ball milling treatments is 15 min to 25 min, and the total ball milling time is 7 h to 9 h, so that a small amount of doping phase is firstly mixed with Ni powder and Fe powder by ball milling at a lower rotation speed, thereby avoiding the introduction of impurity elements during the mixing process.

[0015] In some preferred embodiments of the present invention, the second mixed powder is prepared by intermittent dry ball milling. In some more preferred embodiments of the present invention, the ball-to-material ratio of each ball milling treatment is 1 to 2:1, the rotation speed is 50 r / min to 70 r / min, the ball milling time is 55 min to 65 min, the interval between two adjacent ball milling treatments is 55 min to 65 min, and the total ball milling time is 7 h to 9 h, so that the first mixed powder and a large amount of W powder are effectively mixed on a large scale, and the uniform distribution of each element in the raw material mixture is achieved.

[0016] In some preferred embodiments of the present invention, in order to ensure that the first mixed powder is fully mixed with the W powder, the present invention further passes a mixture of Ni powder, Fe powder and doped phase powder through a 200-mesh sieve and mixes it with the W powder as the first mixed powder.

[0017] In some preferred embodiments of the present invention, in order to improve the density of the slab, the present invention further passes the mixture of the first mixed powder and the W powder through a 200-mesh sieve and is used as the second mixed powder to be pressed into a slab.

[0018] In some preferred embodiments of the present invention, when the slab is pressed into a blank, the density of the slab should be greater than 75%.

[0019] Step 2, densification treatment:

[0020] The slab is subjected to a densification treatment in a hydrogen atmosphere to obtain a sintered slab.

[0021] It should be noted that the present invention improves the flatness and deformation of the slab by densification treatment. And in some preferred embodiments of the present invention, the slab is first pre-sintered in the same furnace to improve the density and strength of the sample, and then sintered to achieve a one-step densification process, effectively improving the flatness and deformation of the sample. The present invention directly completes the pre-sintering and sintering processes in the powder metallurgy process by two-stage heating in the same furnace, effectively shortening the process flow and realizing the sintering preparation of large-sized slabs.

[0022] And in some more preferred embodiments of the present invention, the densification process is specifically achieved by the following steps:

[0023] The slab is heated to 1000°C-1200°C and kept warm for 1h-4h to achieve pre-sintering of the slab, and then heated to 1420°C-1560°C and kept warm for 2h-6h to achieve sintering of the slab. By adjusting the process parameters, the pre-sintering and sintering processes can be completed directly in the same furnace to prepare a sintered slab with good shape and density.

[0024] Step 3: Process the slab into several rods:

[0025] The sintered slab is hot rolled and then machined into a plurality of rods.

[0026] It should be noted that the present invention firstly increases the deformation through hot rolling treatment, and machines the large-size slabs after initial rolling into multiple rods from the same batch, so that the rods in the same batch are all derived from the same piece of rod. By effectively controlling the source of the rods between the same batches, the foundation is laid for the stability of the final rods in terms of density, mechanical properties, etc.

[0027] In some preferred embodiments of the present invention, the hot rolling process is achieved by the following steps:

[0028] The sintered slab is heated to 800°C-1000°C and kept warm for 1 hour, and then rolled. During the rolling process, the deformation of a single pass is controlled to be ≤10%, and the total deformation is 15%-50%.

[0029] In some preferred embodiments of the present invention, the machining is achieved by the following steps: after the sintered slab after hot rolling is cooled to room temperature, it is machined into a plurality of rods along the rolling direction by water jet cutting and lathe processing.

[0030] Step 4, post-processing:

[0031] After vacuum annealing, several of the bar blanks are subjected to a rotary forging process and then vacuum heat treatment to effectively improve the stability of the same batch of high-density tungsten alloy bars.

[0032] It should be noted that the present invention realizes the preparation of the same batch of high-performance W-Ni-Fe alloy bars by subjecting a plurality of the bar blanks to vacuum annealing and then subjecting them to a rotary forging process to increase the deformation again, and then combining the vacuum heat treatment, thereby effectively improving the stability of the same batch of W-Ni-Fe alloy bars in terms of composition, density and mechanical properties.

[0033] In some preferred embodiments of the present invention, during the rotary forging process, the deformation of the rotary forging is strictly controlled by controlling the deformation of the single pass to ≤8% and the total deformation to 10% to 35%, thereby effectively reducing the performance difference between the bar blanks caused by rotary forging. The present invention first performs a hot rolling process for preliminary deformation processing, and then performs a rotary forging process for secondary deformation processing, and controls the total deformation in the hot rolling process to be 15% to 50%, while the total deformation set in the rotary forging process is 10% to 35%. That is, the present invention controls the deformation in the hot rolling process to be greater than the deformation set in the rotary forging process, thereby effectively improving the stability of the bars in the same batch and reducing the influence of the fluctuation of the mechanical properties of the final bars during the forging process.

[0034] In some preferred embodiments of the present invention, the temperature of the vacuum annealing is 550°C to 830°C.

[0035] In some preferred embodiments of the present invention, the temperature of the vacuum heat treatment is 550°C to 830°C.

[0036] Compared with the prior art, the present invention has the following beneficial effects:

[0037] The present invention uses one or more of Mo powder, Re powder, Zr powder and Co powder as doped phase powder, adopts a two-stage mixing process for mixing, and first mixes Ni powder, Fe powder and doped phase powder, and then adds W powder for mixing, so as to effectively disperse the doped phase in the main raw material for preparing W-Ni-Fe high-density tungsten alloy rods, realize the uniform distribution of each element in the raw material mixture, and then improve the flatness and deformation of the slab by densification treatment. Subsequently, the deformation amount is preliminarily improved by hot rolling treatment, and by machining the large-sized slab after initial rolling into multiple rods of the same batch, the source of the rods between the same batch is effectively controlled, and the stability of the final rods in terms of density, mechanical properties, etc. is laid. Then, secondary deformation processing is carried out by rotary forging process processing, so as to realize the step-by-step deformation processing of the rods between the same batches by hot rolling and rotary forging process processing, so as to effectively improve the stability of the rods between the same batches, and reduce the influence of the fluctuation of the mechanical properties of the final rods during forging. Combined with vacuum heat treatment, the preparation of high-performance W-Ni-Fe alloy rods in the same batch was achieved, which effectively improved the stability of the same batch of W-Ni-Fe alloy rods in terms of composition, density and mechanical properties.

[0038] The preparation method of the present invention can achieve the preparation of high-performance W-Ni-Fe alloy rods while effectively improving the stability of the rods in the same batch in terms of density and room temperature mechanical properties. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 This is the metallographic structure image of the high specific gravity tungsten alloy rod prepared in Example 1 at a scale of 100 μm.

[0040] Figure 2 This is the metallographic structure image of the high specific gravity tungsten alloy rod prepared in Example 1 at a scale of 50 μm.

[0041] Figure 3 This is the metallographic structure image of the high specific gravity tungsten alloy rod prepared in Example 3 at a scale of 100 μm.

[0042] Figure 4 This is the metallographic structure image of the high specific gravity tungsten alloy rod prepared in Example 3 at a scale of 50 μm. DETAILED DESCRIPTION

[0043] The technical solutions in the embodiments of the present invention will be described clearly and completely below.

[0044] Example 1

[0045] This embodiment provides a processing method for improving the performance stability of high specific gravity tungsten alloy bars of the same batch, comprising the following steps:

[0046] Step 1, prepare the slab:

[0047] 1.1) In this embodiment, tungsten alloy with a grade of 93W-4.9Ni-2.1Fe is used as the high-density tungsten alloy to be upgraded. According to the composition of the tungsten alloy with a grade of 93W-4.9Ni-2.1Fe, corresponding masses of W powder, Ni powder and Fe powder are weighed and set aside.

[0048] 1.2) Co powder and Mo powder are used as doping phases together, and the amount of Co powder added is 0.3wt% of the total mass of W powder, Ni powder and Fe powder, and the amount of Mo powder added is 0.3wt% of the total mass of W powder, Ni powder and Fe powder. The corresponding mass of Co powder and Mo powder are weighed and set aside.

[0049] 1.3) The weighed Ni powder, Fe powder and doping phase powder are mixed and intermittently dry-milled, and the ball-to-material ratio of each ball milling treatment is controlled to be 2:1, the rotation speed is 100 r / min, the ball milling time is 20 min, the interval between two adjacent ball milling treatments is 20 min, the total ball milling time is 8 h, and the ball milling product is passed through a 200-mesh sieve to obtain a first mixed powder.

[0050] 1.4) The weighed W powder is added to the first mixed powder, followed by intermittent dry ball milling, and the ball-to-material ratio of each ball milling treatment is controlled to be 1.5:1, the rotation speed is 60 r / min, the ball milling time is 60 min, the interval between two adjacent ball milling treatments is 60 min, the total ball milling time is 8 h, and the ball milling product is passed through a 200 mesh sieve to obtain a second mixed powder.

[0051] 1.5) The second mixed powder is pressed into a blank to obtain a slab.

[0052] Step 2, densification treatment:

[0053] The slab obtained in step 1.5) is placed in a hydrogen furnace, heated to 1050°C in a hydrogen atmosphere and kept warm for 2 hours, then heated to 1495°C and kept warm for 4 hours to prepare a sintered slab with a size of 216 mm×305 mm×60 mm.

[0054] Step 3: Process the slab into several rods:

[0055] 3.1) The sintered slab obtained in step 2 above is heated to 910° C. in an atmospheric furnace and kept at this temperature for 1 hour, and then rolled using a rolling mill, and during the rolling process, the single pass deformation is controlled to be 5% and the total deformation is controlled to be 20%.

[0056] 3.2) After the sintered slabs after the hot rolling treatment in 3.1) above are cooled to room temperature, they are machined into 9 rods with a size of φ30 mm×245 mm along the rolling direction by water jet cutting and lathe processing.

[0057] Step 4, post-processing:

[0058] 4.1) Place the 9 rods with a size of φ30 mm × 245 mm obtained in 3.2) above in a vacuum annealing furnace, heat to 830°C and keep warm for 2 hours.

[0059] 4.2) The bar blank after vacuum annealing in 4.1) is heated again to 710° C. in an atmospheric furnace and forged by rotary forging, with the single-pass deformation amount controlled to 5% and the total deformation amount controlled to 30%.

[0060] 4.3) The surface of the rod blank treated by the rotary forging process in 4.2) was polished and kept at 600°C for 1 hour to obtain 9 high-density tungsten alloy rods with a size of φ23mm×280mm.

[0061] And through the room temperature mechanical property test of 9 high specific gravity tungsten alloy rods with a size of φ23mm×280mm obtained in this embodiment, it is known that the tensile strength of the 9 W-Ni-Fe alloy rods in the same batch of this embodiment is in the range of 1470MPa~1476MPa, the elongation is in the range of 14.4%~14.6%, and the density is 17.32g / cm 3 This indicates that the same batch of rod blanks prepared by the preparation method of this embodiment have good stability, that is, the preparation method of the present invention can effectively improve the stability of the same batch of high specific gravity tungsten alloy rods.

[0062] Example 2

[0063] This embodiment provides a processing method for improving the performance stability of high specific gravity tungsten alloy bars of the same batch, comprising the following steps:

[0064] Step 1, prepare the slab:

[0065] 1.1) In this embodiment, tungsten alloy with a grade of 90W-7Ni-3Fe is used as the high-density tungsten alloy to be upgraded. According to the composition of the tungsten alloy with a grade of 90W-7Ni-3Fe, corresponding masses of W powder, Ni powder and Fe powder are weighed and set aside.

[0066] 1.2) Co powder, Mo powder and Re powder are used as doping phases together, and the amount of Co powder added is 0.2wt% of the total mass of W powder, Ni powder and Fe powder, the amount of Mo powder added is 0.2wt% of the total mass of W powder, Ni powder and Fe powder, and the amount of Re powder added is 0.2wt% of the total mass of W powder, Ni powder and Fe powder. The corresponding mass of Co powder, Mo powder and Re powder are weighed and set aside.

[0067] 1.3) The weighed Ni powder, Fe powder and doping phase powder are mixed and intermittently dry-milled, and the ball-to-material ratio of each ball milling treatment is controlled to be 2:1, the rotation speed is 150 r / min, the ball milling time is 20 min, the interval between two adjacent ball milling treatments is 20 min, the total ball milling time is 8 h, and the ball milling product is passed through a 200-mesh sieve to obtain a first mixed powder.

[0068] 1.4) The weighed W powder is added to the first mixed powder, followed by intermittent dry ball milling, and the ball-to-material ratio of each ball milling treatment is controlled to be 1.5:1, the rotation speed is 60 r / min, the ball milling time is 60 min, the interval between two adjacent ball milling treatments is 60 min, the total ball milling time is 8 h, and the ball milling product is passed through a 200 mesh sieve to obtain a second mixed powder.

[0069] 1.5) The second mixed powder is pressed into a blank to obtain a slab.

[0070] Step 2, densification treatment:

[0071] The slab obtained in step 1.5) is placed in a hydrogen furnace, heated to 1000°C in a hydrogen atmosphere and kept warm for 4 hours, then heated to 1420°C and kept warm for 6 hours to prepare a sintered slab with a size of 184 mm×302 mm×40 mm.

[0072] Step 3: Process the slab into several rods:

[0073] 3.1) The sintered slab obtained in step 2 is heated to 810° C. in an atmospheric furnace and kept at this temperature for 1 hour, and then rolled using a rolling mill. During the rolling process, the deformation of a single pass is controlled to be 6% and the total deformation is controlled to be 30%.

[0074] 3.2) After the sintered slabs after the hot rolling treatment in 3.1) above are cooled to room temperature, they are machined into 13 rods with a size of φ23 mm×205 mm along the rolling direction by water jet cutting and lathe processing.

[0075] Step 4, post-processing:

[0076] 4.1) The 13 rod blanks with a size of φ23 mm×205 mm obtained in 3.2) above were placed in a vacuum annealing furnace, heated to 550°C and kept at this temperature for 3 hours.

[0077] 4.2) The bar blank after vacuum annealing in 4.1) is heated again to 600° C. in an atmospheric furnace and forged by rotary forging, with the single-pass deformation amount controlled to 8% and the total deformation amount controlled to 32%.

[0078] 4.3) The surface of the rod blank treated by the rotary forging process in 4.2) was polished and kept at 600°C for 1 hour to obtain 13 high-density tungsten alloy rods with a size of φ18mm×230mm.

[0079] Furthermore, by conducting room temperature mechanical property tests on 13 high-density tungsten alloy rods with a size of φ18 mm×230 mm obtained in this embodiment, it was found that the tensile strength of the 13 W-Ni-Fe alloy rods in the same batch of this embodiment was in the range of 1426 MPa to 1434 MPa, and the elongation was in the range of 15.9% to 16.4%, which indicates that the stability of the same batch of rod blanks prepared by the preparation method of this embodiment is good, that is, the preparation method of the present invention can effectively improve the stability of the same batch of high-density tungsten alloy rods.

[0080] Example 3

[0081] This embodiment provides a processing method for improving the performance stability of high specific gravity tungsten alloy bars of the same batch, comprising the following steps:

[0082] Step 1, prepare the slab:

[0083] 1.1) In this embodiment, tungsten alloy with a grade of 95W-3.5Ni-1.5Fe is used as the high-density tungsten alloy to be upgraded. According to the composition of the tungsten alloy with a grade of 95W-3.5Ni-1.5Fe, corresponding masses of W powder, Ni powder and Fe powder are weighed and set aside.

[0084] 1.2) Co powder and Re powder are used as doping phases together, and the amount of Co powder added is 0.4wt% of the total mass of W powder, Ni powder and Fe powder, and the amount of Re powder added is 0.2wt% of the total mass of W powder, Ni powder and Fe powder. The corresponding mass of Co powder and Re powder are weighed and set aside.

[0085] 1.3) The weighed Ni powder, Fe powder and doping phase powder are mixed and intermittently dry-milled, and the ball-to-material ratio of each ball milling treatment is controlled to be 2:1, the rotation speed is 100 r / min, the ball milling time is 20 min, the interval between two adjacent ball milling treatments is 20 min, the total ball milling time is 8 h, and the ball milling product is passed through a 200-mesh sieve to obtain a first mixed powder.

[0086] 1.4) The weighed W powder is added to the first mixed powder, followed by intermittent dry ball milling, and the ball-to-material ratio of each ball milling treatment is controlled to be 1.5:1, the rotation speed is 60 r / min, the ball milling time is 60 min, the interval between two adjacent ball milling treatments is 60 min, the total ball milling time is 8 h, and the ball milling product is passed through a 200 mesh sieve to obtain a second mixed powder.

[0087] 1.5) The second mixed powder is pressed into a blank to obtain a slab.

[0088] Step 2, densification treatment:

[0089] The slab obtained in step 1.5) is placed in a hydrogen furnace, heated to 1200°C in a hydrogen atmosphere and kept warm for 4 hours, then heated to 1560°C and kept warm for 2 hours to prepare a sintered slab with a size of 192 mm×302 mm×40 mm.

[0090] Step 3: Process the slab into several rods:

[0091] 3.1) The sintered slab obtained in step 2 is heated to 1000° C. in an atmospheric furnace and kept at this temperature for 1 hour, and then rolled using a rolling mill. During the rolling process, the deformation of a single pass is controlled to be 6% and the total deformation is controlled to be 42%.

[0092] 3.2) After the sintered slab after the hot rolling treatment in 3.1) is cooled to room temperature, it is machined into 13 rods with a size of φ18 mm×213 mm along the rolling direction by water jet cutting and lathe processing.

[0093] Step 4, post-processing:

[0094] 4.1) The 13 rod blanks with a size of φ18 mm×213 mm obtained in 3.2) above were placed in a vacuum annealing furnace, heated to 700°C and kept at this temperature for 2 hours.

[0095] 4.2) The bar blank after vacuum annealing in 4.1) is heated again to 700° C. in an atmospheric furnace and forged by rotary forging, with the single-pass deformation amount controlled to 5% and the total deformation amount controlled to 35%.

[0096] 4.3) The surface of the rod blank treated by the rotary forging process in 4.2) was polished and then kept at 600°C for 1 hour to obtain 13 high-density tungsten alloy rods with a size of φ13mm×225mm.

[0097] Furthermore, by conducting room temperature mechanical property tests on 13 high-density tungsten alloy rods with a size of φ13mm×225mm obtained in this embodiment, it was found that the tensile strength of the 9 W-Ni-Fe alloy rods in the same batch of this embodiment was in the range of 1504MPa~1510MPa, and the elongation was in the range of 9.8%~10.2%, which indicates that the stability of the same batch of rod blanks prepared by the preparation method of this embodiment is good, that is, the preparation method of the present invention can effectively improve the stability of the same batch of high-density tungsten alloy rods.

[0098] Comparative Example 1

[0099] This comparative example provides a processing method for improving the performance stability of the same batch of high-density tungsten alloy bars, comprising the following steps:

[0100] Step 1, prepare the rod blank:

[0101] 1.1) In this comparative example, a tungsten alloy with a grade of 93W-4.9Ni-2.1Fe is used as a comparative test. According to the composition of the tungsten alloy with a grade of 93W-4.9Ni-2.1Fe, corresponding masses of W powder, Ni powder and Fe powder are weighed and set aside.

[0102] 1.2) Co powder and Mo powder are used as doping phases together, and the amount of Co powder added is 0.3wt% of the total mass of W powder, Ni powder and Fe powder, and the amount of Mo powder added is 0.3wt% of the total mass of W powder, Ni powder and Fe powder. The corresponding mass of Co powder and Mo powder are weighed and set aside.

[0103] 1.3) The weighed Ni powder, Fe powder and doping phase powder are mixed and intermittently dry-milled, and the ball-to-material ratio of each ball milling treatment is controlled to be 2:1, the rotation speed is 100 r / min, the ball milling time is 20 min, the interval between two adjacent ball milling treatments is 20 min, the total ball milling time is 8 h, and the ball milling product is passed through a 200-mesh sieve to obtain a first mixed powder.

[0104] 1.4) The weighed W powder is added to the first mixed powder, followed by intermittent dry ball milling, and the ball-to-material ratio of each ball milling treatment is controlled to be 1.5:1, the rotation speed is 60 r / min, the ball milling time is 60 min, the interval between two adjacent ball milling treatments is 60 min, the total ball milling time is 8 h, and the ball milling product is passed through a 200 mesh sieve to obtain a second mixed powder.

[0105] 1.5) The second mixed powder is directly pressed into 10 rods of the same size.

[0106] Step 2, densification treatment:

[0107] The rod blank obtained in the above step 1.5) is placed in a hydrogen furnace, heated to 1050°C in a hydrogen atmosphere and kept warm for 2 hours, then heated to 1495°C and kept warm for 4 hours, to prepare 10 sintered rod blanks with a size of φ30×200 mm.

[0108] Step 3, post-processing:

[0109] 3.1) Place the 10 rod blanks with a size of φ30 mm × 200 mm obtained in step 2 above in a vacuum annealing furnace, heat to 830°C and keep warm for 2 hours.

[0110] 3.2) The bar blank after vacuum annealing in 3.1) is heated again to 710° C. in an atmospheric furnace and forged by rotary forging, with the single-pass deformation amount controlled to 5% and the total deformation amount controlled to 50%.

[0111] 3.3) The surface of the rod blank treated by the rotary forging process in 4.2) was polished and kept at 600°C for 1 hour to obtain 10 high-density tungsten alloy rods with a size of φ20mm×370mm.

[0112] The difference between this comparative example and Example 1 is:

[0113] The steel is directly pressed into 10 rods of the same size and then subjected to densification treatment.

[0114] And through the room temperature mechanical property test of 10 high specific gravity tungsten alloy bars with a size of φ20mm×370mm obtained in this comparative example, it is known that the tensile strength of the 10 W-Ni-Fe alloy bars of the same batch of this comparative example is in the range of 1320MPa~1447MPa, and the elongation is in the range of 13.3%~14.8%. It can be seen that the tensile strength and elongation of the same batch of bars prepared in this comparative example fluctuate greatly, which indicates that the stability of the same batch of bar blanks prepared by the preparation method of this comparative example is poor. Compared with Example 1, it can be seen that the slab is first pressed into a slab and then densified, and then the sintered slab after densification is rolled and converted into a number of bar blanks, which can effectively improve the stability of bars in the same batch and reduce the influence of the fluctuation of the mechanical properties of the final bar during the forging process.

[0115] The present invention also takes the high specific gravity tungsten alloy rods prepared in Example 1 and Example 3 as examples, and tests the metallographic structures thereof, and the test results are as follows: Figure 1 to Figure 4 shown.

[0116] in, Figure 1 This is the metallographic structure image of the high specific gravity tungsten alloy rod prepared in Example 1 at a scale of 100 μm. Figure 2 The metallographic structure image of the high-density tungsten alloy rod prepared in Example 1 at a scale of 50 μm shows that the microstructure of the high-density tungsten alloy rod prepared in Example 1 of the present invention is relatively uniform, the tungsten grains are uniformly distributed in the binding phase (Ni-Fe), and the tungsten grains are in the form of elongated strips, which is beneficial to improving the tensile strength and other mechanical properties of the alloy material.

[0117] Figure 3 This is the metallographic structure image of the high specific gravity tungsten alloy rod prepared in Example 3 at a scale of 100 μm. Figure 4 The metallographic structure image of the high specific gravity tungsten alloy rod prepared in Example 3 at a scale of 50 μm shows that the tungsten grains can be elongated in the same direction by the method of first rolling and then forging, and some tungsten grains are in an interwoven state, which is beneficial to improving the room temperature mechanical properties of the alloy material.

[0118] Obviously, the above embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

Claims

1. A method for improving the performance stability of high-density tungsten alloy bars of the same batch, characterized in that: The following steps are involved: According to the composition of the W-Ni-Fe high-density tungsten alloy to be upgraded, weigh corresponding masses of W powder, Ni powder and Fe powder for use; mix the weighed Ni powder and Fe powder, add the doping phase powder and mix well to obtain a first mixed powder; add the weighed W powder to the first mixed powder and mix well to obtain a second mixed powder; press the second mixed powder into a blank to obtain a slab; Wherein, the doped phase powder is one or more of Mo powder, Re powder, Zr powder and Co powder; the addition amount of the doped phase powder is ≤ 1wt% of the total mass of W powder, Ni powder and Fe powder; Densifying the slab in a hydrogen atmosphere to obtain a sintered slab; Hot rolling the sintered slab and then machining it into a plurality of rods; After vacuum annealing, several of the bar blanks are subjected to a rotary forging process and then vacuum heat treatment to improve the stability of the same batch of high-density tungsten alloy bars.

2. The method for improving the performance stability of high-density tungsten alloy bars of the same batch as claimed in claim 1, characterized in that: The W-Ni-Fe series high specific gravity tungsten alloy rods are W-Ni-Fe series high specific gravity tungsten alloy rods with grades of 90W-7Ni-3Fe, 93W-4.9Ni-2.1Fe and 95W-3.5Ni-1.5Fe.

3. The method for improving the performance stability of high-density tungsten alloy bars of the same batch as claimed in claim 1, characterized in that: The densification process is achieved by the following steps: In the same furnace, the slab is firstly subjected to a pre-sintering treatment and then subjected to a sintering treatment.

4. The method for improving the performance stability of high-density tungsten alloy bars of the same batch as claimed in claim 3, characterized in that: The densification process is specifically achieved by the following steps: The slab is heated to 1000° C. to 1200° C. and then kept warm for 1 h to 4 h to achieve pre-sintering of the slab, and then heated to 1420° C. to 1560° C. and kept warm for 2 h to 6 h to achieve sintering of the slab.

5. The method for improving the performance stability of high-density tungsten alloy bars of the same batch as claimed in claim 1, characterized in that: The hot rolling process is achieved by the following steps: The sintered slab is heated to 800°C-1000°C and kept warm for 1 hour, and then rolled. During the rolling process, the deformation of a single pass is controlled to be ≤10%, and the total deformation is 15%-50%.

6. The method for improving the performance stability of high-density tungsten alloy bars of the same batch as claimed in claim 1, characterized in that: During the rotary forging process, the deformation amount of a single pass is ≤8%, and the total deformation amount is 10% to 35%.

7. The method for improving the performance stability of high-density tungsten alloy bars of the same batch as claimed in claim 1, characterized in that: When preparing the first mixed powder, intermittent dry ball milling is used for preparation; In the intermittent dry ball milling, the ball-to-material ratio of each ball milling treatment is 1 to 3:1, the rotation speed is 100 r / min to 200 r / min, the ball milling treatment time is 15 min to 25 min, the interval between two adjacent ball milling treatments is 15 min to 25 min, and the total ball milling time is 7 h to 9 h.

8. The method for improving the performance stability of high-density tungsten alloy bars of the same batch as claimed in claim 1, characterized in that: When preparing the second mixed powder, intermittent dry ball milling is used for preparation; During the intermittent dry ball milling, the ball-to-material ratio of each ball milling treatment is 1-2:1, the rotation speed is 50r / min-70r / min, the ball milling treatment time is 55min-65min, the interval between two adjacent ball milling treatments is 55min-65min, and the total ball milling time is 7h-9h.

9. The method for improving the performance stability of high-density tungsten alloy bars of the same batch as claimed in claim 1, characterized in that: The temperature of the vacuum annealing is 550°C to 830°C.

10. The method for improving the performance stability of high-density tungsten alloy bars of the same batch as claimed in claim 1, characterized in that: The temperature of the vacuum heat treatment is 550°C to 830°C.

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