TC4 residual material recovery method

Abstract

The invention discloses a TC4 residual material recovery method. The component range of residual materials is determined according to target components of TC4 cast ingots; tC4 residual waste materials are cleaned; packaging the TC4 residual waste material and the Al raw material together to obtain a residual material block; smelting the residual material block through an electron beam cold bed furnace to prepare a primary cast ingot; and the primary cast ingot is smelted through a vacuum consumable electric arc furnace, and a TC4 finished product cast ingot is prepared. According to the method, irregularly-shaped residual waste materials are packaged into residual material blocks, the space occupation of the residual waste materials is reduced, the single-time recovery amount is increased when residual titanium is recovered through electron beam cold bed smelting, and the recovery efficiency is improved. And the Al raw material is directionally and accurately added into each residual material block, so that the volatilization loss amount of Al in smelting is supplemented, and the uniformity of adding the Al raw material is also improved.

Description

Technical Field

[0001] The invention relates to the technical field of titanium alloy ingot casting, and in particular to a TC4 waste material recovery method. Background Art

[0002] High cost is the biggest obstacle to the popularization and application of titanium alloys, so the low cost of titanium materials is one of the important research and development directions of the industry. Ways to reduce the cost of titanium alloys include reducing the cost of raw materials, mainly including the design and development of cheap element titanium alloys and the smelting and recycling of residual titanium.

[0003] In the prior art, a large amount of residual materials and waste materials will be generated during the production and subsequent processing of titanium and titanium alloys. For example, data statistics on its application in the aviation field show that the yield rate of titanium materials from ingots to parts for aviation applications is only 10% to 20%, and 75% of titanium processed materials to aircraft parts have become blocks, chips, punching chips, etc. to form residual waste materials. For example, in the application of directly recycling used mobile phone frames, some of the residual materials are small in size, irregular in shape, and occupy a large smelting space. When the residual titanium is recycled and reused through electron beam cold bed smelting, the single recovery amount is small, the recovery efficiency is low, and the uniformity of the chemical elements of the ingot is poor.

[0004] In view of the above, it is necessary to propose a TC4 waste recycling method to solve the above problems. Summary of the invention

[0005] The purpose of the present invention is to overcome the defects in the prior art and provide a TC4 waste material recovery method.

[0006] To achieve the above object, the technical solution of the present invention is as follows: a TC4 waste material recovery method, comprising the following steps: Determining the composition range of the TC4 scrap material according to the target composition range of the TC4 ingot; washing the TC4 scrap material, wherein the length of the TC4 scrap material is less than 80 mm and the TC4 scrap material is irregular in shape; Packing the TC4 waste into waste blocks by a hydraulic packing machine; adding Al raw materials into the TC4 waste blocks; Melting a plurality of the residual blocks in an electron beam cooling furnace to prepare a primary ingot; The primary ingot is melted in a vacuum consumable arc furnace to prepare a TC4 finished ingot.

[0007] Furthermore, the packaging method of the waste block is a multiple pressing packaging method, in which TC4 waste materials are added multiple times and pressed accordingly to form multiple waste material layers, and Al raw materials are evenly added between the waste material layers.

[0008] Furthermore, the step of melting the plurality of the residual blocks by using an electron beam cooling furnace comprises: Stacking a plurality of the residual blocks in a feed trough of the electron beam cooling furnace for smelting to prepare a primary ingot; The scrap block is in the shape of a cuboid, and its dimensions are 100-150mm in length, 100-150mm in width, and 140-165mm in height; the feed trough has dimensions of 5000-6000mm in length, 600-800mm in width, and 400-600mm in height; a plurality of the scrap blocks are stacked in sequence from bottom to top along the length direction of the feed trough.

[0009] Furthermore, the step of stacking a plurality of the waste blocks in a feed trough of an electron beam cooling furnace for smelting comprises: The residual block located in the feed trough is melted by the electron gun of the electron beam cooling hearth furnace; the electron gun comprises a first electron gun group, a second electron gun and a third electron gun; the first electron gun group is used to melt the residual block into titanium liquid; the second electron gun is used to refine the titanium liquid; the titanium liquid enters the crystallizer of the electron beam cooling hearth furnace to form a molten pool, and the third electron gun is used to heat the surface of the molten pool.

[0010] Furthermore, the voltage of the first electron gun group is 25-30KV, and the total current is 30-40A; the voltage of the second electron gun is 25-30KV, and the current is 5-7A; the voltage of the third electron gun is 25-30KV, and the current is 10-14A.

[0011] Furthermore, the residual material block is spaced a predetermined distance from a side wall of the feed trough, and the side wall of the feed trough is parallel to a feeding direction.

[0012] Furthermore, the step of melting the primary ingot by a vacuum consumable arc furnace to prepare a TC4 finished ingot comprises: The primary ingot is melted in a crucible with a diameter of 720 mm to prepare a TC4 finished ingot; the melting current is 25-29KA, and the melting voltage is 30-35V.

[0013] Furthermore, the TC4 scrap material is the discarded frame generated during the processing of TC4 wire.

[0014] Furthermore, the step of determining the composition range of TC4 scrap material according to the target composition range of TC4 ingot comprises: the target composition range is Fe: 0.12-0.18; C: <0.03; N: <0.02; H: <0.006; O: 0.09-0.15; Al: 5.85-6.45; V: 3.95-4.35; and the composition range of TC4 scrap material is determined according to the target composition range as Fe: 0.12-0.18; C: <0.03; N: <0.02; H: <0.006; O: 0.09-0.15; Al: 5.85-6.45; V: 3.95-4.35.

[0015] Furthermore, the Al raw material is Al beans, and the mass of the Al raw material accounts for 0.7-0.8% of the mass of the residual material block.

[0016] Furthermore, the step of cleaning the TC4 waste material comprises: Performing alkali washing on the TC4 waste material to remove oil stains on the surface of the TC4 waste material; The TC4 waste material is pickled to remove the oxide layer on the surface of the TC4 waste material.

[0017] Furthermore, during a smelting operation in an electron beam cooling hearth furnace, an ultrasonic oscillation device is arranged on the cooling hearth to apply sound waves with a frequency of 50-100kHz to the liquid surface of the titanium alloy molten pool, which are transmitted to the interior of the molten pool through ultrasonic waves. The ultrasonic vibration is used to promote solute diffusion, improve the distribution of alloy components, and promote the uniform distribution of chemical elements in the ingot.

[0018] Furthermore, directional solidification is adopted in the electron beam cold hearth furnace smelting, and a melting furnace with temperature gradient control is adopted, and the bottom temperature and the top temperature of the crucible are set to form a temperature gradient of 100-200°C / cm; the cooling rate is controlled to be 0.1-1°C / s by adjusting the cooling system. When pulling the ingot, the temperature gradient can be controlled by controlling the ingot pulling speed. If a faster cooling rate and a larger temperature gradient are required, the ingot pulling speed can be appropriately increased; otherwise, the ingot pulling speed is reduced. Generally speaking, the ingot pulling speed is fast, the cooling rate is relatively high, and the solidification interface advancement speed is also fast, which is conducive to the directional solidification. Adjustment is made through real-time feedback. During the ingot pulling process, the temperature changes of the ingot and the molten pool are monitored in real time through the temperature sensor, and the temperature data is fed back to the control system of the ingot puller. The control system automatically adjusts the ingot pulling speed according to the deviation between the actual temperature and the set temperature gradient and cooling rate to keep the temperature gradient and cooling rate within the process requirements. In this process, it can be coordinated with the heating of the third electron gun or the cooling system set. During the ingot pulling process, the electron gun continuously provides heat to the molten pool to maintain the temperature of the liquid metal in the molten pool. The ingot puller reasonably controls the ingot pulling speed according to the heating power of the electron gun and the temperature of the molten pool, ensuring that there is always enough heat supply at the solidification front of the ingot during the ingot pulling process, maintaining a stable temperature gradient, and allowing solidification to proceed from the bottom of the crucible upward to achieve directional solidification. The cooling system cools the bottom of the crucible and the crystallizer. When the ingot puller pulls the ingot, it must ensure that the ingot is cooled at a predetermined cooling rate under the action of the cooling system. For example, when the cooling water flow rate and flow rate are stable, the ingot puller controls the ingot pulling speed so that the ingot can solidify quickly and maintain the directional solidification structure morphology under the action of the cooling system after leaving the crystallizer. The ingot puller can also generate a slight vibration during the ingot pulling process, and the vibration frequency and amplitude can be adjusted. For example, the vibration frequency is controlled at 5-15Hz and the amplitude is 1-2mm. This slight vibration is conducive to promoting the uniform and dense distribution of the melt in the crystallizer, making the solidification process more uniform, and helping to improve the quality of the ingot and the directional solidification effect.

[0019] The advantages and beneficial effects of the present invention are as follows: the present invention packs TC4 waste materials with irregular shapes and lengths less than 80 mm into waste blocks to reduce the smelting space occupied by the waste materials, increases the single recovery amount when the residual titanium is recovered by electron beam cold bed smelting, improves the recovery efficiency, and improves the uniformity of the chemical composition of the ingot. Since a large amount of Al will volatilize during the smelting process, by adding Al raw materials to each waste block in a targeted and precise manner, the volatilization loss of Al during smelting is supplemented, and the uniformity of the added Al raw materials is improved. The composition range of the TC4 waste materials is determined according to the target composition range of the TC4 ingot, so as to increase the proportion of TC4 waste materials in a single ingot. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a schematic diagram of the preparation process of the present invention; Figure 2 It is a cross-sectional schematic diagram of the placement of the residual material blocks in the feed trough in the present invention; Figure 3 It is a top view of the residual material blocks placed in the feed trough in the present invention; Figure 4 is a sampling position diagram of the titanium alloy ingot in the present invention; Figure 5 is the scanning trajectory diagram of the first electron gun group; Figure 6 is the T-shaped scanning trajectory diagram of the second electron gun; Figure 7 is the directional scanning trajectory diagram of the second electron gun; Figure 8 is a scanning area diagram of the third electron gun; Fig. 9 It is a schematic diagram of the ingot casting steps of the electron beam cooling hearth furnace; Fig.10 It is a schematic diagram of the placement of wedges in the VAR furnace of the present invention; Fig.11 This is a schematic diagram of the structure of the wedge block in the VAR furnace of the present invention. Figure 1 ; Fig.12 This is a schematic diagram of the structure of the wedge block in the VAR furnace of the present invention. Figure 2 ; In the figure, 1 is the feed trough; 2 is the residual material block; 31 is the wedge; 32 is the bottom plate; 33 is the first side plate; 34 is the second side plate; 35 is the rib plate; 36 is the scale line; 37 is the weight reduction hole; 38 is the consumable electrode; 39 is the crystallizer; 41 is the scanning trajectory of the first electron gun group; 42 is the T-shaped scanning trajectory of the second electron gun; 43 is the square scanning trajectory of the second electron gun; 44 is the third scanning area; 45 is the fourth scanning area; 46 is the melting area; 47 is the cooling bed; 48 is the refining area; 49 is the crystallization area. DETAILED DESCRIPTION

[0021] The specific implementation of the present invention is further described below in conjunction with the accompanying drawings and embodiments. The following embodiments are only used to more clearly illustrate the technical solution of the present invention, and cannot be used to limit the protection scope of the present invention.

[0022] A TC4 waste material recovery method, such as Figure 1 As shown, the following steps are included: Determining the composition range of the TC4 scrap material according to the target composition range of the TC4 ingot; washing the TC4 scrap material, wherein the length of the TC4 scrap material is less than 80 mm and the TC4 scrap material is irregular in shape; The TC4 scrap material is packaged into scrap blocks by a hydraulic baler; Al raw material is added to the TC4 scrap block; specifically, the scrap block is packaged by a multiple pressing and packaging method, TC4 scrap material is added multiple times and pressed accordingly to form multiple scrap layers, and Al raw material is evenly added between the scrap layers. In actual use, a portion of the TC4 scrap material can be placed at the bottom of the mold and pressed once, and Al raw material is evenly distributed on the upper plane of the scrap layer formed by pressing. Optionally, the aluminum raw material can be pressed once to fix it; or the TC4 scrap material can be added and pressed together. In this way, some TC4 scrap material is added and pressed to form another scrap layer. Through multiple feeding and pressing, the TC4 scrap material is finally packaged to form a scrap block with supplementary Al raw material evenly distributed inside.

[0023] It is understandable that the TC4 scrap material and the Al raw material can also be pre-mixed and then pressed once; this pressing method is not as uniform as the aforementioned multiple pressing method in terms of the distribution of the Al raw material. In order to improve the uniform mixing effect of this method, the TC4 scrap material can be crushed before pressing and then mixed with the aluminum raw material for pressing.

[0024] Melting a plurality of the residual blocks in an electron beam cooling furnace to prepare a primary ingot; The primary ingot is melted in a vacuum consumable arc furnace to prepare a TC4 finished ingot.

[0025] The present invention packs TC4 waste materials with irregular shapes and lengths less than 80 mm into waste blocks to reduce the smelting space occupied by the waste materials, increases the single recovery amount when the residual titanium is recovered by electron beam cold bed smelting, improves the recovery efficiency, and improves the uniformity of the chemical composition of the ingot. Since a large amount of Al will volatilize during the smelting process, by adding Al raw materials to each waste block in a targeted and precise manner, the volatilization loss of Al during smelting is supplemented and the uniformity of the added Al raw materials is improved. The composition range of the TC4 waste materials is determined according to the target composition range of the TC4 ingot, so as to increase the proportion of TC4 waste materials in a single ingot.

[0026] Furthermore, the step of melting the plurality of the residual blocks by using an electron beam cooling furnace comprises: Stacking a plurality of the residual blocks in a feed trough of the electron beam cooling furnace for smelting to prepare a primary ingot; The scrap block is in the shape of a cuboid, and its dimensions are 100-150mm in length, 100-150mm in width, and 140-165mm in height; the feed trough has dimensions of 5000-6000mm in length, 600-800mm in width, and 400-600mm in height; a plurality of the scrap blocks are stacked in sequence from bottom to top along the length direction of the feed trough.

[0027] The scrap block is designed to be a cuboid, with the length, width and height being within the range of 100-150mm, 100-150mm and 140-165mm. This relatively regular and small size is convenient for manual or mechanical operation and handling. In the recycling process, whether transferring the scrap block from one place to another or placing it in a specific device (such as a feed chute), it is easier to operate, reducing labor intensity and operating difficulty, and improving work efficiency.

[0028] The feed chute is designed with specifications of 5000-6000mm in length, 600-800mm in width and 400-600mm in height, providing a large space. It can accommodate multiple scrap blocks for stacking along the length direction, which can meet the needs of large-scale batch processing of TC4 scraps. During the production process, a large number of scrap blocks can be loaded at one time, reducing the number of frequent filling of the feed chute, improving the overall production efficiency and reducing the unit processing cost.

[0029] The larger width and height of the feed trough allow enough space for the residual blocks to be arranged and moved during the feeding process, which helps to achieve uniform feeding of materials. It avoids problems such as uneven accumulation of residual blocks due to small feeding space, which in turn causes inconsistent feeding speed or blockage. Uniform feeding is crucial to the stability of smelting. For example, during the smelting process, uniform feeding can ensure uniform heat transfer and smooth reaction in the molten pool, which is conducive to improving the quality of ingots.

[0030] Furthermore, the step of stacking a plurality of the waste blocks in a feed trough of an electron beam cooling furnace for smelting comprises: The residual block located in the feed trough is melted by the electron gun of the electron beam cooling hearth furnace; the electron gun comprises a first electron gun group, a second electron gun and a third electron gun; the first electron gun group is used to melt the residual block into titanium liquid; the second electron gun is used to refine the titanium liquid; the titanium liquid enters the crystallizer of the electron beam cooling hearth furnace to form a molten pool, and the third electron gun is used to heat the surface of the molten pool.

[0031] Furthermore, the voltage of the first electron gun group is 25-30KV, and the total current is 30-40A; the voltage of the second electron gun is 25-30KV, and the current is 5-7A; the voltage of the third electron gun is 25-30KV, and the current is 10-14A.

[0032] By rationally allocating the melting power of the first electron gun group, the second electron gun and the third electron gun, the melting rate, refining rate and crystallization rate of the residual block are matched, ensuring the uniformity of the composition of various elements in the TC4 titanium alloy ingot and effectively reducing inclusions and segregation in the alloy.

[0033] Furthermore, the first scanning image of the first electron gun group is spiral, and the scanning movement trajectory of the first electron gun group during rotation scanning is as follows: Figure 5 As shown, the first electron gun group is Figure 5 During the moving process of the track shown, a circular scan is made to form a spiral reciprocating scanning track, thereby forming a spiral covering scan to scan and melt the raw material without dead angles; the second scanning image of the second electron gun switches between square and T-shape. When performing the refining operation, a square scanning image is used, such as Figure 7 As shown; when the titanium liquid begins to flow toward the crystallizer, the scanning image switches to a T shape, as shown Figure 6 shown.

[0034] By designing the scanning image of the first electron gun group into a spiral shape, a larger range of scanning can be achieved, ensuring that the TC4 scrap is heated evenly during the melting process, accelerating the melting process of the scrap, and providing sufficient and uniform titanium liquid raw materials for subsequent refining and crystallization processes.

[0035] The scanning image of the second electron gun has the function of switching between square and T-shape. When the refining operation is mainly carried out, a square scanning image is used. At this time, the electron beam can be concentrated in a specific area of ​​the molten pool, and the titanium liquid is deeply refined with a higher energy density, effectively removing the impurity elements therein and improving the purity of the titanium liquid. When the titanium liquid begins to flow to the crystallizer, the scanning image switches to a T-shape. The characteristic of the T-shaped scanning image is that it can cover the key area from the molten pool to the overflow port of the crystallizer. By effectively heating this area, it ensures that the titanium liquid maintains good fluidity in the process of flowing to the crystallizer, and prevents the overflow port from being blocked due to temperature reduction or impurity accumulation, thereby ensuring the continuity and stability of the entire smelting and crystallization process, and helping to obtain high-quality, internally uniform and defect-free TC4 titanium alloy ingots.

[0036] Furthermore, the first scanning areas of the four first electron gun groups are symmetrically arranged with respect to the cooling bed of the electron beam cooling bed furnace; and the second scanning area of ​​the second electron gun coincides with the central axis of the cooling bed.

[0037] The symmetrical arrangement of the four first scanning areas enables the TC4 scrap to be irradiated with a relatively balanced electron beam at all locations on the cooling bed, so that the raw materials are heated evenly during the melting process, avoiding uneven melting caused by local overheating or overcooling, which is beneficial to improving the melting efficiency and ensuring the stability of the quality of the titanium liquid. The second scanning area of ​​the second electron gun coincides with the central axis of the cooling bed. When the second electron gun performs a refining operation on the titanium liquid, this overlapping layout design allows the refining process to radiate evenly around the central axis of the cooling bed, ensuring that the titanium liquid in the entire molten pool can be fully and evenly refined.

[0038] Furthermore, the third electron gun includes a first gun and a second gun, and the third scanning area of ​​the first gun is circular, such as Figure 8 As shown, the center of the third scanning area coincides with the center of the crystallizer, and the fourth scanning area of ​​the second gun is annular and located between the edge of the crystallizer and the third scanning area.

[0039] In the electron gun setting of the electron beam cooling furnace, the third electron gun is composed of the first gun and the second gun. The third scanning area of ​​the first gun is circular, and the center of the circle coincides with the center of the crystallizer. In this way, when the first gun heats the surface of the molten pool, it can transfer heat to the periphery more evenly with the center of the crystallizer as the center, thereby heating the central area of ​​the molten pool.

[0040] The fourth scanning area of ​​the second gun is annular, and its position is between the edge of the crystallizer and the third scanning area of ​​the first gun, that is, surrounding the outside of the center area of ​​the molten pool. This annular scanning area forms a clever combination with the circular scanning area of ​​the first gun.

[0041] In the actual process of heating the molten pool surface, the combination of the annular and circular scanning areas can cover the entire molten pool surface more comprehensively and evenly than heating by relying solely on the circular scanning area. Fig. 9 As shown, all parts of the molten pool surface can obtain appropriate and uniform heat supply, thereby effectively improving the uniformity of the molten pool surface temperature, creating a good and stable thermal environment for the crystallization process of the titanium alloy in the molten pool, helping to ensure uniform crystallization rate and uniform and dense ingot structure, and ultimately improving the quality of TC4 titanium alloy ingots.

[0042] Furthermore, the ingot pulling speed for melting through the electron beam cooling furnace is 10-15 mm / min.

[0043] The ingot pulling speed affects the height and stability of the molten pool level, as well as the solidification process of the ingot. If the ingot pulling speed is too fast, the molten pool level will drop too quickly, which may cause the aluminum rod to be partially exposed on the surface of the molten pool, affecting its melting and composition uniformity; if the ingot pulling speed is too slow, the molten pool level may be too high, increasing the pressure and temperature gradient in the molten pool, and easily causing defects such as shrinkage cavities and cracks. Therefore, the ingot pulling speed should be reasonably adjusted according to factors such as the smelting rate, molten pool size, and ingot specifications to ensure that the molten pool level remains stable, so that the aluminum rods are melted and evenly mixed in a suitable molten pool environment, and at the same time ensure that the ingot can form a good organizational structure during the solidification process.

[0044] Furthermore, the scrap block is spaced a predetermined distance from the side wall of the feed trough, and the side wall of the feed trough is parallel to the feeding direction. The predetermined distance may be 10-20 mm to prevent the scrap block from being stuck by the weld of the side wall of the feed trough during electron beam cold bed melting.

[0045] Furthermore, the step of melting the primary ingot by a vacuum consumable arc furnace to prepare a TC4 finished ingot comprises: The primary ingot is melted in a crucible with a diameter of 720 mm to prepare a TC4 finished ingot; the melting current is 25-29KA, and the melting voltage is 30-35V.

[0046] Furthermore, the TC4 scraps are waste frames generated during the processing of TC4 wires. Packing and compressing TC4 small-volume irregular scraps, such as mobile phone frame scraps, can reduce the space occupied by the scraps, increase the loading capacity of the feed trough, and increase the proportion of recycled scraps, thereby improving the recycling rate of the scraps.

[0047] Further, the step of determining the composition range of TC4 scrap material according to the target composition range of TC4 ingot includes: the target composition range is Fe: 0.12-0.18; C: <0.03; N: <0.02; H: <0.006; O: 0.09-0.15; Al: 5.85-6.45; V: 3.95-4.35; the composition range of TC4 scrap material is determined according to the target composition range as Fe: 0.12-0.18; C: <0.03; N: <0.02; H: <0.006; O: 0.09-0.15; Al: 5.85-6.45; V: 3.95-4.35. That is, the target composition range of the ingot is consistent with the composition range of the TC4 scrap material. Furthermore, the Al raw material is Al beans, and the mass of the Al raw material accounts for 0.7-0.8% of the mass of the residual material block. When Al beans are added, Al beans and TC4 residual materials are simultaneously put into the compression mold of the baler, mixed evenly, packaged and compressed, and the density is based on not being loose and falling off.

[0048] The evenly distributed Al element during the smelting process helps to form a more uniform alloy structure, avoid the uneven performance of TC4 caused by local element enrichment or depletion, and improve the overall performance stability of TC4 materials.

[0049] This ensures that the mixing ratio of TC4 residue and Al beans in each portion can be kept consistent, ensuring the consistency of the entire batch of materials.

[0050] By packing and compressing to a density that does not loosen or fall off, the mixture of TC4 residue and Al beans can maintain a stable shape during transportation and is not easy to scatter, thus avoiding the loss of Al raw materials.

[0051] Furthermore, the step of cleaning the TC4 waste material comprises: Performing alkali washing on the TC4 waste material to remove oil stains on the surface of the TC4 waste material; The TC4 waste material is pickled to remove the oxide layer on the surface of the TC4 waste material.

[0052] The purpose of cleaning TC4 waste materials with alkaline solution is to remove the oil stains attached to the surface of the waste materials. The oil stains may come from the previous processing, storage or use process, and their presence will affect the subsequent treatment and recycling of the waste materials. Alkaline washing can cause the oil stains to undergo saponification or emulsification, thereby separating them from the surface of the waste materials and achieving the effect of cleaning the surface.

[0053] After alkaline washing, pickling is performed to remove the oxide layer on the surface of TC4 scrap using an acidic solution. During the use and storage of titanium and titanium alloy materials, an oxide layer will inevitably form on the surface, which will cause the ingot oxygen content to exceed the standard and produce low-density oxide inclusions. Pickling can dissolve and remove the oxide layer, so that the surface of the scrap material is restored to the standard that meets the quality requirements of the smelting raw materials.

[0054] Embodiment 1: Step 1: The target composition of the ingot is Fe: 0.12-0.18; C: <0.03; N: <0.02; H: <0.006; O: 0.09-0.15; Al: 5.85-6.45; V: 3.95-4.35; Select TC4 waste materials with composition range of Fe: 0.12-0.18; C: <0.03; N: <0.02; H: <0.006; O: 0.09-0.15; Al: 5.85-6.45; V: 3.95-4.35; The TC4 small volume irregular residues are pickled to remove the oxide layer, and the TC4 waste materials are ultrasonically treated before smelting. Ultrasonic waves can effectively remove pollutants such as oxides and oil stains on the surface of the raw materials, thereby improving the purity of the raw materials. Then, the TC4 small volume residues are compressed into cubic residue blocks using a hydraulic baler, and the residue blocks are stacked in the feed trough; Since aluminum volatilizes in large quantities during electron beam cold bed melting, a predetermined weight of aluminum beans is added to each cubic scrap block to compensate for the loss of aluminum. Other raw materials in the scrap block are pressed with recycled TC4 scrap materials.

[0055] The amount of each raw material used is determined according to the target composition of the ingot and the weight of the ingot specification. Considering that a large amount of Al will volatilize during the smelting process, the amount of Al beans added is determined according to the Al element loss. According to data summary and analysis, when the total smelting power of the EB furnace is 3000-3500KW, the Al element loss is 0.7-0.8%. In this embodiment, the total weight of the ingot is 5100kg. That is, the amount of Al beans added accounts for 0.7-0.8% of the total amount of a single residual block. In this embodiment, 0.7% is taken as an example. The total amount of Al beans actually used is 35.7kg, so the amount of TC4 waste used is 5064.3kg, and the recovery rate of TC4 waste is 99.3%; the waste block layout is as follows Figure 2 As shown; several layers of residual blocks are closely arranged in the feed trough, and each layer of residual blocks is closely fitted with several residual blocks in the horizontal and vertical directions. Specifically, the feed trough is 5000×800×500mm in specification, and the residual blocks are 150×150×150mm in specification; the actual number of residual blocks pressed is 340; and 105g of aluminum beans should be added to each residual block on average; In actual fabrication, there are three layers of fabric in the height direction, five pieces of fabric in the width direction, and 33 pieces of fabric in the length direction; Figure 3 As shown, after the material is distributed, a distance is left between the edge of the pile of residual material blocks and the feed trough on both sides and the front and rear ends; 340 residual material blocks are evenly distributed in the feed troughs of the left and right feed chambers on both sides of the EB furnace.

[0056] Step 2: Put the feed trough into the EB cooling bed furnace feeding system, and evacuate the left and right feeding chambers and the melting chamber until the vacuum degree of the feeding chamber is ≤0.6Pa and the vacuum degree of the melting chamber is ≤0.1Pa, then start smelting. During the smelting process, the vacuum degree of the melting chamber meets ≤0.5Pa. After the TC4 titanium alloy residue is bombarded by the electron beam and melted into titanium liquid, it flows into the crystallizer crucible for solidification through the melting cooling bed and the refining cooling bed, and then the ingot is pulled to the ingot pulling chamber through the ingot pulling system, cooled with the furnace, and then taken out of the furnace to obtain an ingot with a diameter of 650mm. There are a total of seven electron guns in the EB cooling bed furnace, No. 1-7, and the power of the electron gun is 280~440kV.

[0057] During the smelting process, guns 1-4 are used to melt the raw materials in the left and right feed tanks, gun 5 is used to refine the titanium liquid in the cooling bed, and guns 6-7 are used to heat the surface of the molten pool in the crystallizer so that the titanium liquid in the molten pool can be continuously solidified. The power distribution of each gun in EB smelting is shown in Table 1.

[0058] Table 1 Serial number Melting power ratio 1-4 60-70% 5 10-15% 6-7 20-25% Step 3: The ingot melted in the EB furnace is subjected to secondary melting in a VAR furnace through a crucible with a diameter of 720, with a melting current of 25-29KA and a melting voltage of 30-35V; finally, a finished ingot with a diameter of 700±10mm is obtained.

[0059] When secondary melting is carried out in a VAR furnace, Figure 10-12 As shown, the specific process is as follows: multiple wedges are evenly placed between the top edge of the consumable electrode and the crystallizer cylinder, and one end of each wedge with an angle b is inserted into the gap between the consumable electrode and the crystallizer cylinder. By adjusting the position of the consumable electrode, multiple wedges are at the same horizontal height to achieve a uniform gap between the consumable electrode and the crystallizer. The consumable electrode is located at the center of the crystallizer. Since the material of the first side plate and the second side plate of the bottom plate is the same as the alloy material for vacuum consumable arc melting, foreign matter is prevented from being brought into the crystallizer during the furnace loading process to cause pollution to the melting; since the material is an alloy, the structural strength is improved, and the positioning device can avoid deformation that causes uneven gap between the consumable electrode and the crystallizer, affecting melting safety and ingot quality; it is also avoided that during the welding process of the consumable electrode and the auxiliary electrode, the positioning device is prevented from spontaneously igniting at high temperature, resulting in increased air pressure in the crystallizer, affecting welding safety.

[0060] Specifically, the length L1 of the wedge 31 is 200-300 mm, the width L2 is 80-150 mm, and the thickness L3 is 80-150 mm.

[0061] Specifically, the included angle a between the bottom plate 32 and the first side plate 33 is in the range of 90°-150°, and the included angle b between the bottom plate 32 and the second side plate 34 is in the range of 15°-45°; Specifically, the bottom plate 32, the first side plate 33 and the second side plate 34 are integrally formed; considering that the specifications of the crystallizer 39 and the consumable electrode 38 are numerous and the sizes of different specifications are also different, in order to ensure that the wedge 31 can be effectively used, the size of the wedge 31 and the sizes of the angle a and the angle b are also various, so that the staff can select a suitable wedge 31 according to the specifications of the crystallizer 39 and the consumable electrode 38. At the same time, the raw material of the wedge 31 is mainly taken from the titanium alloy plate in the waste material, and the titanium alloy plate is appropriately processed according to its own size to make it a wedge 31 that meets the above requirements.

[0062] Specifically, the wedge 31 also includes two ribs 35, and the two ribs 35 are symmetrically arranged on both sides of the bottom plate 32; the ribs 35 are triangular, and the three sides of the ribs 35 are respectively connected to the bottom plate 32, the first side plate 33 and the second side plate 34. Considering that the bottom plate 22, the first side plate 33 and the second side plate 34 alone cannot form a closed structure of the wedge 31, ribs 55 are welded on both sides thereof, so that the wedge 31 has a closed structure as a whole, thereby improving the overall strength of the wedge 31.

[0063] Specifically, the ribs 35 are provided with scale lines 36 with marking functions in the vertical direction; the scale lines 36 are used to observe the insertion depth of the wedges 31. When the scale lines 36 on the bottom plates 32 of the plurality of wedges 31 are at the same vertical distance from the top edge of the consumable electrode 38, it means that the plurality of wedges 31 are at the same horizontal height, thereby achieving the purpose of improving positioning accuracy.

[0064] Specifically, the scale lines are laser etched, chemically etched or mechanically engraved, which improves the clarity and wear resistance of the scale lines and makes them less likely to wear out or become blurred during the use of the wedge.

[0065] Specifically, the corners of the wedge 31 are chamfered; in order to prevent the wedge 31 from causing scratches to the operator during use, and to reduce the scratches on the surface of the consumable electrode 38 and the crystallizer 39 during the insertion and adjustment of the wedge 31, chamfers are set at the corners of the wedge 31, and the chamfer radius ranges from 0.5mm to 3mm.

[0066] Specifically, the bottom plate 32 , the first side plate 33 and the second side plate 34 are all provided with weight-reducing holes 37 ; in order to reduce the weight of the wedge 31 itself, a plurality of weight-reducing holes 37 are provided thereon.

[0067] Two ingots were prepared through the above steps, and the sampling positions of the titanium alloy ingots were as follows: Figure 4As shown, the ingot composition was tested, and the test results are shown in Table 2. After testing, all the requirements of the target range were met.

[0068] Table 2 Ingot 1 composition test results

[0069] Embodiment 2: Step 1: The target composition of the ingot is Fe: 0.12-0.18; C: <0.03; N: <0.02; H: <0.006; O: 0.09-0.15; Al: 5.85-6.45; V: 3.95-4.35; the TC4 waste material with the composition range of Fe: 0.12-0.18; C: <0.03; N: <0.02; H: <0.006; O: 0.09-0.15; Al: 5.85-6.45; V: 3.95-4.35 is selected; The TC4 small volume irregular residues are pickled to remove the oxide layer, and the TC4 waste materials are ultrasonically treated before smelting to effectively remove oxides, oil stains and other pollutants on the surface of the raw materials, thereby improving the purity of the raw materials. Then, the TC4 small volume residues are compressed into cubic residue blocks using a hydraulic baler, and the residue blocks are stacked in the feed trough; Since aluminum volatilizes in large quantities during electron beam cold bed melting, a predetermined weight of aluminum beans is added to each cubic scrap block to compensate for the loss of aluminum. Other raw materials in the scrap block are pressed with recycled TC4 scrap materials.

[0070] The amount of each raw material used is determined according to the target composition of the ingot and the weight of the ingot specification. Considering that a large amount of Al will volatilize during the smelting process, the amount of Al beans added is determined according to the Al element loss. According to data summary and analysis, when the total smelting power of the EB furnace is 3000-3500KW, the Al element loss is 0.8%. In this embodiment, the total weight of the ingot is 6000kg. That is, the amount of Al beans added accounts for 0.7-0.8% of the total amount of a single residual block. In this embodiment, 0.8% is taken as an example. The total amount of Al beans actually used is 48kg, so the amount of TC4 waste used is 5952kg, and the recovery rate of TC4 waste is 99.2%; the waste block layout is as follows Figure 2 As shown; several layers of residual blocks are closely arranged in the feed trough, and each layer of residual blocks is closely fitted with several residual blocks in the horizontal and vertical directions. Specifically, the feed trough is 5000×800×500mm in specification, and the residual blocks are 150×150×150mm in specification; the actual number of residual blocks pressed is 400; and 120g of aluminum beans should be added to each residual block on average; In actual fabrication, there are three layers of fabric in the height direction, five pieces of fabric in the width direction, and 33 pieces of fabric in the length direction; Figure 3 As shown, after the material is distributed, a distance is left between the edge of the pile of residual material blocks and the feed trough on both sides and the front and rear ends; 400 residual material blocks are evenly distributed in the feed troughs of the left and right feed chambers on both sides of the EB furnace.

[0071] Step 2: Put the feed trough into the EB cooling bed furnace feeding system, and evacuate the left and right feeding chambers and the melting chamber until the vacuum degree of the feeding chamber is ≤0.6Pa and the vacuum degree of the melting chamber is ≤0.1Pa, then start smelting. During the smelting process, the vacuum degree of the melting chamber meets ≤0.5Pa. After the TC4 titanium alloy residue is bombarded by the electron beam and melted into titanium liquid, it flows into the crystallizer crucible for solidification through the melting cooling bed and the refining cooling bed, and then the ingot is pulled to the ingot pulling chamber through the ingot pulling system, cooled with the furnace, and then taken out of the furnace to obtain an ingot with a diameter of 650mm. There are a total of seven electron guns in the EB cooling bed furnace, No. 1-7, and the power of the electron gun is 280~440kV.

[0072] During the smelting process, guns 1-4 are used to melt the raw materials in the left and right feed troughs, gun 5 is used to refine the titanium liquid in the cooling bed, and guns 6-7 are used to heat the molten pool surface in the crystallizer so that the titanium liquid in the molten pool can solidify continuously.

[0073] Step 3: The ingot melted in the EB furnace is subjected to secondary melting in a VAR furnace through a crucible with a diameter of 720, with a melting current of 25-29KA and a melting voltage of 30-35V; finally, a finished ingot with a diameter of 700±10mm is obtained.

[0074] Two ingots were prepared through the above steps, and the sampling positions of the titanium alloy ingots were as follows: Figure 4 As shown, the ingot composition was tested, and the test results are shown in Table 3. After testing, all the requirements of the target range were met.

[0075] Table 3 Ingot 2 composition test results

[0076] As an improvement in the implementation method of process control in smelting: Specifically applied in EB smelting, the implementation method of directional solidification in electron beam cooling furnace smelting includes: forming a temperature gradient from the bottom to the top of the crucible, and controlling the temperature gradient to 100-200°C / cm. And by adjusting the cooling system, the cooling rate is controlled to 0.1-1°C / s. For example, when the ingot height is 2 meters during the specific implementation, the total temperature difference can reach 200°C to 400°C. Such a temperature gradient helps to ensure that the molten metal in the molten pool can solidify along the expected path.

[0077] Specifically, directional solidification in an EB furnace can be achieved in the following ways: In an electron beam cooling furnace (EB furnace), ingot pulling is performed, that is, the ingot is not stationary in a fixed position to solidify, but moves downward continuously as solidification proceeds. This ingot pulling process is very beneficial for directional solidification because it allows the liquid metal to continuously pass through a controlled temperature field during cooling and solidification. The following controls are performed during specific implementation: 1. Temperature gradient control: Even if the bottom of the crucible is open and the ingot is formed while being pulled down continuously, the required temperature gradient is created by the cooperation of the heating system and the cooling system. The heating system provides sufficient energy to maintain the molten pool, while the cooling system ensures that the lower part of the ingot (the part that has solidified) is cooled while maintaining the appropriate superheat above the molten pool. In this way, a stable temperature gradient is formed between the ingot and the furnace, which gradually transitions from the high temperature zone at the top to the low temperature zone at the bottom.

[0078] By adjusting the heating system in the melting furnace, a significant temperature difference is established between the bottom and top of the crucible, forming the aforementioned temperature gradient of 100-200℃ / cm. This high temperature gradient ensures that the liquid metal gradually cools and solidifies from the bottom to the top, allowing the crystallization process to proceed in a specific direction.

[0079] 2. Cooling rate control: The ingot pulling speed is directly related to the cooling rate. By adjusting the ingot pulling speed, the cooling rate of the ingot can be effectively controlled. A slower ingot pulling speed means a longer exposure to the cooling environment, resulting in a lower cooling rate; on the contrary, a faster ingot pulling speed will reduce the exposure time and increase the cooling rate. Therefore, in actual production, the ingot pulling speed can be set as needed to achieve an ideal cooling rate of 0.1-1°C / s.

[0080] The cooling rate is controlled by adjusting the parameters of the cooling system. In this process, the cooling rate is set to 0.1-1°C / s to ensure an appropriate solidification speed, neither too fast nor too slow, which helps to form an ideal crystal structure. A slower cooling rate is conducive to promoting orderly atomic arrangement and reducing defects.

[0081] 3. Dynamic control system: In order to ensure the stability of temperature gradient and cooling rate throughout the process, the use of automatic control systems is coordinated. These systems can monitor temperature, ingot pulling speed and other key parameters in real time, and automatically make adjustments based on monitoring data to ensure consistency of conditions throughout the casting process.

[0082] According to the above-mentioned embodiment: for an ingot with a diameter of 720 mm and a weight of about 6 tons, the use of directional solidification can maintain a stable temperature gradient throughout the solidification process, promote uniform and continuous movement of the solidification front, and thus obtain a better microstructure.

[0083] As an improved implementation method in EB smelting, during a smelting operation in an electron beam cooling hearth furnace, an ultrasonic oscillation device is arranged on the cooling bed, and ultrasonic waves are transmitted to the inside of the molten pool. The ultrasonic vibration is used to promote solute diffusion, improve alloy component distribution, and promote uniform distribution of chemical elements in the ingot.

[0084] Apply sound waves with a frequency of 50-100kHz to the surface of the titanium alloy molten pool. When the ultrasonic wave propagates to the surface of the titanium alloy molten pool, the energy it carries will cause the vibration of the surface molecules. When the ultrasonic wave propagates in the molten pool, it will propagate in multiple modes such as longitudinal waves and transverse waves. The longitudinal wave causes the liquid molecules in the molten pool to produce compression and stretching vibrations in the propagation direction, while the transverse wave causes the molecules to produce shear vibrations perpendicular to the propagation direction. These vibration modes are superimposed on each other, making the vibration of the molten pool surface more complex and comprehensive, ensuring that the entire liquid surface is subjected to uniform vibration. The use of ultrasonic oscillation can produce the following advantages.

[0085] 1. Enhance convection diffusion The vibration of the molten pool surface will drive the flow of the liquid inside the entire molten pool, forming convection. This convection effect is stronger than natural convection, which can make the alloy elements in the molten pool diffuse faster in the liquid. The alloy elements that were originally unevenly distributed in the molten pool will migrate from the high-concentration area to the low-concentration area under the action of convection, thus gradually achieving uniform distribution.

[0086] 2. Breaking the concentration gradient The vibration caused by ultrasound can break the concentration gradient of alloy elements in the molten pool. In the absence of vibration, alloy elements may form local areas of uneven concentration due to factors such as density differences, resulting in uneven material properties. Through the strong stirring effect generated by vibration, these areas of uneven concentration are broken, and the alloy elements are more fully mixed, ultimately achieving a uniform distribution of alloy elements in the entire molten pool, improving the quality and performance of titanium alloys.

[0087] In this embodiment, a method of using ultrasonic oscillation in one smelting process is compared with a method of not using ultrasonic oscillation. The specific process is as follows: Installation location of ultrasonic oscillation device: ultrasonic transducers are installed at the bottom or side of the cooling bed to ensure that the ultrasonic wave can directly act on the molten pool. The transducers should be evenly distributed to cover the entire molten pool area to ensure uniform ultrasonic vibration effect. To prevent the ultrasonic transducer from overheating, an efficient cooling water cooling system is equipped to ensure the normal use of the ultrasonic oscillation device; the ultrasonic oscillation device is integrated with the existing smelting control system to accurately control the opening time, duration and intensity of the ultrasonic wave to ensure the best effect.

[0088] Comparison test data list of ingot quality with and without oscillation Test items Using ultrasonic vibration (US) No US Al element distribution Standard deviation σ = 0.03 wt%, average content 6.18 wt% Standard deviation σ = 0.05 wt%, average content 6.15 wt% V element distribution Standard deviation σ = 0.02 wt%, average content 4.12 wt% Standard deviation σ = 0.03 wt%, average content 4.1 wt% From the data in the above table, it can be seen that the TC4 titanium alloy ingot using the ultrasonic oscillation device (US) shows further advantages in many aspects, specifically: the microstructure is more uniform. The chemical composition distribution is more uniform, especially for elements that are easy to segregate, such as aluminum (Al) and vanadium (V), which reduces the phenomenon of component segregation. Higher tensile strength, yield strength and better ductility reflect stronger mechanical properties. There are almost no internal defects inside, and ultrasonic vibration helps gas escape and inclusions float, making the ingot quality better. The change from the surface to the core is smaller, showing better material consistency and more uniform hardness distribution.

[0089] These improvements not only improve the overall quality of the ingot, but also enhance the consistency and reliability of the material, which is particularly suitable for applications with extremely high material performance requirements, such as the aerospace industry. Therefore, in the actual production and quality control process, the combination of directional solidification technology and the application of ultrasonic oscillation devices can significantly improve the quality of the ingot.

[0090] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the technical principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A TC4 waste material recovery method, characterized in that: The following steps are involved: Determining the composition range of TC4 scrap material according to the target composition range of TC4 ingot; washing the TC4 scrap material, wherein the TC4 scrap material is in an irregular shape; Packing the TC4 waste material and the Al raw material into waste blocks by a hydraulic packing machine; Melting a plurality of the residual blocks in an electron beam cooling furnace to prepare a primary ingot; The primary ingot is melted in a vacuum consumable arc furnace to prepare a TC4 finished ingot.

2. A TC4 waste material recovery method according to claim 1, characterized in that: The step of melting the plurality of residual blocks by using an electron beam cooling furnace comprises: Stacking a plurality of the residual material blocks in a feed trough of the electron beam cooling furnace for smelting to prepare a primary ingot; The scrap block is in the shape of a cuboid, and its dimensions are 100-150mm in length, 100-150mm in width, and 140-165mm in height; the feed trough has dimensions of 5000-6000mm in length, 600-800mm in width, and 400-600mm in height; a plurality of the scrap blocks are stacked in sequence from bottom to top along the length direction of the feed trough.

3. A TC4 waste material recovery method according to claim 2, characterized in that: The step of stacking a plurality of the residual material blocks in a feed trough of an electron beam cooling furnace for smelting comprises: The residual block located in the feed trough is melted by the electron gun of the electron beam cooling hearth furnace; the electron gun comprises a first electron gun group, a second electron gun and a third electron gun; the first electron gun group is used to melt the residual block into titanium liquid; the second electron gun is used to refine the titanium liquid; the titanium liquid enters the crystallizer of the electron beam cooling hearth furnace to form a molten pool, and the third electron gun is used to heat the surface of the molten pool.

4. A TC4 waste material recovery method according to claim 3, characterized in that: The voltage of the first electron gun group is 25-30KV, and the total current is 30-40A; the voltage of the second electron gun is 25-30KV, and the current is 5-7A; the voltage of the third electron gun is 25-30KV, and the current is 10-14A.

5. A TC4 waste material recovery method according to claim 3, characterized in that: During a melting process in an electron beam cooling hearth furnace, an ultrasonic oscillation device is installed on the cooling hearth to apply sound waves with a frequency of 50-100kHz to the liquid surface of the titanium alloy molten pool. The sound waves are transmitted to the inside of the molten pool through ultrasonic waves. The ultrasonic vibration is used to promote solute diffusion, improve the distribution of alloy components, and promote the uniform distribution of chemical elements in the ingot.

6. A TC4 waste material recovery method according to claim 3, characterized in that: The step of melting the primary ingot by a vacuum consumable arc furnace to prepare a TC4 finished ingot comprises: The primary ingot is melted in a crucible with a diameter of 720 mm to prepare a TC4 finished ingot; the melting current is 25-29KA, and the melting voltage is 30-35V.

7. A TC4 waste material recovery method according to any one of claims 1 to 6, characterized in that: The step of determining the composition range of the TC4 scrap material according to the target composition range of the TC4 ingot comprises: the target composition range is Fe: 0.12-0.18; C: <0.03; N: <0.02; H: <0.006; O: 0.09-0.15; Al: 5.85-6.45; V: 3.95-4.35; the composition range of the TC4 scrap material is determined according to the target composition range as Fe: 0.12-0.18; C: <0.03; N: <0.02; H: <0.006; O: 0.09-0.15; Al: 5.85-6.45; V: 3.95-4.35; The TC4 scrap material is the discarded frame generated during the processing of TC4 wire.

8. A TC4 waste material recovery method according to any one of claims 1 to 6, characterized in that: The Al raw material is Al beans, and the mass of the Al raw material accounts for 0.7-0.8% of the mass of the residual material block.

9. A TC4 waste material recovery method according to any one of claims 1 to 6, characterized in that: The step of cleaning the TC4 waste material comprises: Performing alkali washing on the TC4 waste material to remove oil stains on the surface of the TC4 waste material; The TC4 waste material is pickled to remove the oxide layer on the surface of the TC4 waste material.

10. A TC4 waste material recovery method according to claim 1, characterized in that: The packaging method of the waste block is a multiple pressing packaging method, in which TC4 waste materials are added multiple times and pressed accordingly to form multiple waste material layers, and Al raw materials are evenly added between the waste material layers.

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