Preparation method of TC4 titanium alloy cast ingot with high recovery ratio and high uniformity

Abstract

The invention discloses a high-recovery-ratio and high-uniformity TC4 titanium alloy cast ingot preparation method which comprises the following steps: selecting titanium alloy plate-shaped materials to process material frames, and arranging a plurality of material frames in a material box of an EB furnace; the recycled titanium alloy material is classified and sampled to analyze chemical components. Pressing sponge titanium, the intermediate alloy and aluminum shots into an electrode pressing block; the electrode pressing block is arranged in the middle of the material frame, the recycled material stacks are stacked in the material frame in a staggered mode, and gaps are filled. Performing primary smelting through an electron beam cooling bed to obtain a primary cast ingot; and VAR smelting is conducted, specifically, the primary cast ingot is loaded into a VAR furnace to be subjected to secondary smelting. According to the preparation method of the TC4 titanium alloy cast ingot with the high recovery ratio and the high uniformity, an EB + VAR smelting process is adopted, the addition proportion of the recovered materials is high, and the alloy cast ingot with uniform components is prepared.

Description

Technical Field

[0001] The invention relates to the technical field of titanium alloy preparation, and in particular to a method for preparing a TC4 titanium alloy ingot with a high recovery ratio and high uniformity. Background Art

[0002] Titanium alloys are widely used in aviation, aerospace, ships, weapons, biomedicine, chemical metallurgy, marine engineering, sports and leisure, 3C electronics and other fields due to their high specific strength, good corrosion resistance, low thermal conductivity, good high and low temperature resistance, and good biocompatibility.

[0003] Titanium and titanium alloy processed materials have the characteristics of long processing flow, high process energy consumption, and low yield rate, which will form a large amount of residual materials and waste during their production and subsequent processing. For example, 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 materials.

[0004] Titanium alloy uses sponge titanium with a certain proportion of intermediate alloy as raw material, and is melted into titanium alloy ingots by vacuum arc melting (VAR) or electron beam cold hearth melting (EBCHM), and then processed into the required shape by forging, rolling and other processes.

[0005] The process of vacuum consumable arc melting (VAR) is to mix the raw materials in a certain proportion, press them into electrode blocks of a certain specification with a hydraulic press, weld them into "round rod-shaped" consumable electrodes, and then vacuum melt them in a VAR furnace into round titanium alloy ingots (generally repeated melting is required 2 times or more). In the VAR melting process, the consumable electrode drips to the bottom of the crucible after arc melting, and gradually solidifies into an ingot. Vacuum consumable furnace melting requires welding electrodes in advance, and has high requirements on the shape and size of the materials. The shapes of TC4 waste and ingot heads and tails are extremely irregular, and the ability of vacuum consumable arc melting to recover residual materials is low; and the titanium alloy prepared therefrom has metallurgical defects such as high and low density inclusions and macro segregation.

[0006] Electron beam cold hearth melting (EBCHM) is a metallurgical technology that combines electron beam and cold hearth to perform melting under high vacuum. The main feature is that the high-current electron beam of the electron gun is used as the melting heat source, and the kinetic energy of high-speed electrons is converted into heat energy to melt the metal. The molten metal flows in a specially designed cold hearth to remove impurities and refine, and to make the composition uniform. The molten metal flows to the crystallizer through the pouring nozzle at the front end of the cold hearth, and finally solidifies sequentially in the crystallizer and is pulled out by the ingot pulling system to form an ingot. Using an electron beam cold hearth furnace to recycle and remelt TC4 waste has a strong technical advantage, and can fully remove high and low density inclusions, which is crucial for the production of high-end products such as titanium alloys for aerospace. It can effectively utilize various forms of return materials. However, since the main alloying element Al in TC4 waste is much larger than the matrix element, if it is directly remelted, the Al element will inevitably volatilize and lose a large area, resulting in the final TC4 ingot chemical composition failing to meet the standard.

[0007] Secondly, since the titanium alloy residues and waste are of irregular shapes and sizes, it also has a certain impact on the recycling of titanium alloy residues, making its recovery rate low.

[0008] In view of the above, it is necessary to propose a method for preparing TC4 titanium alloy ingots with high recovery ratio and high uniformity to solve the above problems. Summary of the invention

[0009] The purpose of the present invention is to overcome the defects in the prior art and provide a method for preparing TC4 titanium alloy ingots with high recovery ratio and high uniformity.

[0010] To achieve the above object, the technical solution of the present invention is as follows: A method for preparing a TC4 titanium alloy ingot with high recovery ratio and high uniformity, comprising the following steps: Step 1: Material frame preparation, select suitable (including size and element composition of the plate) titanium alloy plate material and weld it into a material frame, the titanium alloy plate material is new material or recycled material, one or more material frames are arranged in the material box of the EB furnace; the material frame includes a bottom plate and a surrounding plate, and the surrounding plates are arranged around the bottom plate to form a material frame with an open top; Step 2: Preparation of recycled materials. Classify the recycled titanium alloy blocks according to the brand and the same composition standard, and clean the recycled titanium alloy materials of each classification, clean the surface oxide layer, oil stains and dirt, and take samples of the recycled materials for chemical composition analysis as the basis for subsequent batching, including the cleaning of the material frame; Step 3: Electrode briquetting: The chemical composition analysis results of the recycled materials are used as the calculation basis, and the volatilization loss of the aluminum element is taken into consideration. The remaining part is added in the form of sponge titanium + master alloy. The sponge titanium, AlV65 master alloy and aluminum beans are mixed in a fully automatic mixing equipment, and then pressed into electrode briquetting by a hydraulic press; The weight percentage of each material is: titanium sponge 88.0% to 90.0%, AlV65 master alloy 5.5% to 8.0%, aluminum bean 5.0% to 9.0%; Step 4: Laying out the materials, arranging the electrode blocks in the middle of the material frame along the length direction, stacking the recycled titanium alloy blocks of the same composition in the material frame in an offset manner, and using small-sized gap fillers to fill the gaps between the irregular titanium alloy blocks; Step 5: Electron beam cold bed melting, the material frames are stacked into the material box of the feeder in sequence, and sent to the electron beam cold bed furnace for melting. After one melting, a titanium alloy ingot suitable for subsequent VAR melting is obtained, and the ingot is surface treated; Step 6: VAR smelting: the ingot smelted in step 5 is placed in a VAR furnace for secondary smelting; During VAR smelting, the mold diameter is 720mm and 800mm. When the mold diameter is 720mm, the smelting current is 26-31KA, the smelting voltage is 30-35V, the arc stabilization current is AC, and the arc stabilization stirring time is 10-20 seconds; when the mold diameter is 800mm, the smelting current is 28-33KA, and the smelting voltage is 30-35V. The remaining 210-230Kg of smelting is used for shrinkage feeding. After smelting, argon is filled for cooling and the furnace is taken out after cooling for 8h.

[0011] Furthermore, the preparation of the recycled materials also includes the treatment of the block materials, which are washed with acid and alkali, cleaned, and dried for standby use; It also includes the processing of scraps, which are crushed by a crusher to form gap filling materials, washed with high-pressure hot water, dried, and magnetically separated for standby use; Furthermore, the gap filling material includes small particles or powdered titanium alloy material, or sponge titanium, or specially customized titanium alloy particles of different particle sizes.

[0012] Furthermore, the arrangement of the recycled materials in the material frame in step 4 includes the following methods: Step 41: Using a layered loading method, first lay the electrode blocks along the length of the material box, place them in the middle of the cross section of the material box, lay large blocks on both sides, and then sprinkle a layer of small particles or powder gap filler on them to fill the gaps between the large blocks, and then continue to lay large blocks, and repeat this process until the material frame is full; Step 42: During the layered loading process, a vibration device is used to vibrate the material frame so that the gap filling material fills the gaps between the large blocks of material, thereby further reducing the gaps between the recycled blocks of material; Step 43: Before loading into the EB furnace, pre-press the recycled material in the material frame from the top open side to form a tighter block and reduce the gap during loading.

[0013] Furthermore, the step 5 specifically includes the following steps: Step 51: Load the loaded material frame into the horizontal feeding chamber of the EB furnace, close the feeding chamber, close the smelting chamber and lock it, and start the vacuum pumps of each level in turn to evacuate the furnace chamber; Step 52: Push the titanium alloy raw material in the material frame horizontally into an area within the electron beam cooling bed where the electron gun can scan; Step 53: When the vacuum degree reaches the melting requirement, set the scanning parameters of electron guns 1 to 7 and start preheating the electron guns; Step 54: respectively start the electron guns No. 1 to No. 4 in the melting area, the electron gun No. 5 in the refining area, and the electron guns No. 6 to No. 7 in the crystallization area, and perform scanning according to the scanning mode set for each electron gun; Step 55: The titanium alloy raw material is smelted, refined, and solidified in a crystallizer, and then pulled out by an ingot pulling system to form an ingot; Step 56: After the ingot is cooled and taken out of the furnace, the surface of the ingot is finished, including cutting off the ingot bottom starter and turning off the riser flash to obtain a primary ingot with a diameter of 650 mm or 720 mm.

[0014] Further, the No. 1 and No. 2 electron guns are arranged on the same side of the cooling bed in the smelting area, and the No. 3 and No. 4 electron guns are arranged on the other side of the cooling bed; the No. 1 to No. 4 electron guns all cover a rectangular scanning area according to a serpentine continuous return scanning trajectory, and the scanning areas of the No. 1 to No. 4 electron guns are arranged in a field shape and perform full coverage scanning on the cooling bed; The No. 5 electron gun scans the refining area, and the No. 5 electron gun scans the refining area in a serpentine continuous return scanning trajectory; The No. 6 and No. 7 electron guns scan the crystallization area. The two electron guns use concentric circle scanning trajectories that can be contracted and expanded. The No. 6 electron gun is the inner circle and the No. 7 electron gun is the outer circle, which fully covers the crystallization area.

[0015] Furthermore, the current of electron guns No. 1 to No. 4 is 7 to 11A, the current of electron gun No. 5 is 5 to 7A, and the current of electron guns No. 6 and No. 7 is 5 to 7A.

[0016] Furthermore, the pulling speed during the pulling process is 8~11mm / min.

[0017] Furthermore, an online analysis device is used in the primary smelting and / or secondary smelting to monitor the composition of each element in the melt in real time, and the raw material ratio is adjusted according to the detection result; the online analysis device is a laser induced breakdown spectroscopy detection device.

[0018] Furthermore, in the EB furnace, a detection window formed by one or more optical windows is arranged above the molten pool of the cooling hearth furnace to allow the laser to pass through and collect the plasma emission spectrum generated by the laser-induced breakdown spectroscopy, and a holographic grating spectrometer is used to quickly analyze the spectral information from the plasma to determine the actual concentration of each element in the melt.

[0019] Furthermore, in VAR smelting, a LIBS probe is arranged in the gap between the upper side of the consumable electrode and the crucible in the VAR furnace, and a holographic grating spectrometer is used to perform composition analysis on the upper layer of the molten pool during the melting and casting process.

[0020] The advantages and beneficial effects of the present invention are as follows: 1. The present invention provides a method for preparing a TC4 titanium alloy ingot with a high recovery ratio and high uniformity. The EB+VAR smelting process is adopted, and the proportion of recycled material added can reach 10% to 90%, thereby preparing an alloy ingot with uniform composition.

[0021] 2. The present invention greatly improves the utilization rate of titanium alloy waste, reduces a large amount of energy and resource consumption in the production process of titanium alloy raw materials, effectively reduces environmental pollution, reduces carbon emissions, and protects the earth's environment.

[0022] 3. Block recycled materials and scraps of different shapes and sizes can be recycled, effectively improving the recycling rate of residual and waste titanium alloy materials. By analyzing the chemical composition of the recycled materials, qualified titanium alloy ingots can be remelted and cast through appropriate ingredients.

[0023] 4. By pressing the electrode compact, a certain amount of aluminum beans and AlV65 master alloy are added to the electrode compact to supplement the volatilization loss of Al element in the EB furnace; and the specific scanning trajectory, scanning frequency and scanning speed of the electron gun are combined to make the surface of the molten pool heated evenly to avoid excessive local temperature, thereby reducing the volatilization loss of Al element and making the Al content in the ingot within the standard range. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a schematic diagram of the cross-sectional structure of the material frame in the present invention; Figure 2 It is a schematic diagram of the structure inside the EB furnace of the present invention; Figure 3 It is the scanning track of the electron gun in the melting zone and the refining zone in the present invention; Figure 4 It is a location diagram for sampling the two ingot products in the present invention; Figure 5 It is a position diagram for sampling the riser and the ingot bottom cross section of the ingot in the present invention; In the figure: 1. material frame; 2. bottom plate; 3. enclosure; 4. electrode briquette; 5. recycled material. DETAILED DESCRIPTION

[0025] 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.

[0026] The production process of titanium sponge and titanium processed materials consumes a lot of energy and resources, and also produces certain environmental pollution. The waste generated in the titanium production process is recycled after special treatment, which can not only reduce dependence on natural resources, but also reduce environmental impact, reduce carbon emissions, and protect the earth's environment. At present, titanium processed material manufacturers mostly use VAR smelting to utilize recycled materials, welding the cleaned block recycled materials into consumable electrodes, or crushing and cleaning the scraps and mixing them with titanium sponge in a certain proportion, pressing them into electrode blocks, and then welding them into consumable electrodes. Due to its own characteristics, the VAR smelting method has its limitations in the production process of high recovery ratio titanium alloy ingots: 1. The recycled materials need to be pressed and welded to electrodes, and there are certain requirements for the shape of the recycled materials; 2. The high-density inclusions and low-density inclusions in the recycled materials cannot be removed, and the metallurgical quality and purity are not as good as EB smelting. The quality level of recycled ingots produced by this method can only meet the requirements of low-end civilian fields.

[0027] A method for preparing TC4 titanium alloy ingots with high recovery ratio and high uniformity. In this embodiment, the recovery ratio is 80%, the total feed is 6 tons, Step 1: Raw material batching: 4.8 tons of surface-treated block TC4 recycled materials, and the remaining 1.2 tons are sponge titanium and master alloy, including 83.3wt% (1000Kg) of sponge titanium, 7.6% (91.457Kg) of AlV65 master alloy, 8.48wt% (101.9Kg) of pure aluminum beans, and 0.59% (7.122Kg) of 32% titanium-iron alloy, which are stored separately; A material frame 1 is prepared by welding titanium alloy plates of suitable size, wherein the material frame 1 comprises a bottom plate 2 and a surrounding plate 3. The surrounding plates 3 are arranged around the bottom plate 2 to form a material frame 1 with an open top; the titanium alloy plate material is new material or recycled material 5.

[0028] Step 2: Mix and press into blocks to prepare electrode briquette 4: Load the titanium sponge, AlV65 master alloy, pure aluminum beans, and 32% titanium-iron alloy described in step 1 into the silo of the fully automatic mixing equipment, load the master alloy into the special silo on the mixing equipment, load the same batch of titanium sponge into one silo, and load different batches of titanium sponge into different silos.

[0029] Automatic weighing is carried out according to the ingredient requirements. The weighed titanium sponge and intermediate alloy are sent to a conical mixer for mixing. After mixing, they are sent to an 8,000-ton hydraulic press to be pressed into 4 electrode blocks, with a total of 20 blocks pressed.

[0030] EB furnace smelting is carried out under high vacuum and high temperature conditions. Although high vacuum is conducive to the removal of low-melting-point volatile metals and impurities, it is difficult to control high vapor pressure alloy components in titanium alloys, such as Al elements. As an α-stabilizing element, Al elements exist in almost all titanium alloys, including titanium alloys. Controlling the burning and volatilization of low-melting-point high vapor pressure elements has become a key factor restricting the smelting of titanium alloys in the cold hearth furnace. During EB furnace smelting, Al elements are accompanied by burning, so when making electrode briquette 4, it is necessary to consider the supplement of the burned Al elements; for example, when the total smelting power of the EB furnace is 3000-3500KW, the loss of Al elements is 0.7-1.0%, and the total weight of the ingot is 3000-6000kg; that is, the supplementary addition of Al elements (including AlV65 master alloy and aluminum beans) in the electrode briquette 4 accounts for 0.7-1.0% of the total weight of a single residual block.

[0031] Step 3: Material distribution: Place the material blocks pressed into the electrode blocks 4 in step 2 in a single layer in the middle of the feeding frame 1, one block per row. The blocky TC4 recycled material 5 is distributed on the left, right and top of the electrode blocks 4, as shown in the figure. Figure 1 The figure shows a cross section inside the material frame 1. The electrode block 4 is located in the middle of the bottom, and the two sides and the upper space are the stacking space for the recycled material 5. The specific stacking method is: The electrode blocks 4 are arranged in the middle of the material frame 1 along the length direction, and the titanium alloy blocks of the same composition are stacked in a staggered manner in the material frame 1, and the gaps between the irregular titanium alloy blocks are filled and compacted with small-sized gap filling materials; ① Use the layered loading method, first lay a layer of large blocks, then sprinkle a layer of small particles or powder gap filler on it to fill the gaps between the large blocks, and then continue to lay large blocks, and repeat this process until the material frame is full; ② During the layered loading process, use vibration equipment to vibrate the material frame, such as a vibration table. This type of equipment generates vibration to cause relative displacement between material particles, further reducing the gaps between the recovered blocks, thereby filling the gaps and achieving a dense effect.

[0032] ③ Before loading into the EB furnace, pre-press the recycled material in the material frame from the top open side to form a tighter block and reduce the gap during loading.

[0033] As an embodiment, the method further includes processing the scraps, wherein the scraps are crushed by a crusher to form gap filling materials; As another embodiment, the gap filling material includes small particles or powdered titanium alloy material, or sponge titanium, or specially customized titanium alloy particles of different particle sizes.

[0034] Before using the block-shaped or chip-shaped recycled materials, they need to be cleaned and prepared, which includes classifying the recycled titanium alloy blocks according to the brand and the same composition standards, and cleaning the titanium alloy recycled materials of each classification, removing the surface oxide layer, oil stains and dirt, and washing with acid and alkali, cleaning, and drying them for use. The recycled materials are sampled for chemical composition analysis as the basis for subsequent batching, including the cleaning of the material frame.

[0035] Step 4: ① Load the loaded material frame into the horizontal feed chamber of the EB furnace. Multiple material frames can be neatly arranged in the feed chamber. A complete material frame can also be placed in the material box of the feed chamber. At this time, the length, width and height of the material frame should match the size of the material box and should be slightly smaller than the size of the material box. Close the feed chamber, close the melting chamber and lock it. Turn on the vacuum pumps at each level in turn to evacuate the furnace chamber.

[0036] ② Push the titanium alloy raw material in the material frame horizontally at a speed of 18mm / min into the area that can be scanned by the electron gun in the electron beam cooling bed.

[0037] ③ When the vacuum degree reaches 1pa, set the scanning parameters of electron guns 1 to 7, the scanning frequency is 70-100HZ, among which the current of electron guns 1 to 4 is 1~5A, the current of electron gun 5 is 1~3A, and the current of electron guns 6~7 is less than 1A, and start preheating the electron guns.

[0038] ④Gradually increase the current of No. 1~5 electron guns, continuously expand the scanning track area, start to melt the material in the cooling bed, start to push the material into the area that can be scanned by the electron gun in the cooling bed, the titanium liquid begins to flow into the crystallizer, and gradually increase the current of No. 6~7 electron guns. Increase the current to heat the ingot bottom support in the crystallizer to avoid rapid cooling of the alloy liquid when it flows in, which will cause the crystallization quality of the ingot bottom to deteriorate.

[0039] ⑤ In the stable smelting stage, the current of No. 1 to 4 electron guns is controlled at 7~10A, the current of No. 5 electron gun is controlled at 5~7A, and the current of No. 6~7 electron guns is controlled at 5~7A. The feeding speed of the feeder is kept stable so that the material flows steadily from the cooling bed into the crystallizer. The pushing speed is selected to be 17~19mm / min; the ingot pulling speed is 8~11mm / min.

[0040] like Figure 2As shown in FIG. 1 , the No. 1 and No. 2 electron guns are arranged on the same side of the cooling bed in the smelting area, and the No. 3 and No. 4 electron guns are arranged on the other side of the cooling bed; the No. 1 to No. 4 electron guns all cover a rectangular scanning area according to a serpentine continuous return scanning trajectory, and the scanning areas of the No. 1 to No. 4 electron guns are arranged in a field shape and fully cover the cooling bed; the serpentine melting trajectory is as shown in FIG. Figure 3 As shown, the scanning track is the scanning image, which can also be set to be circular, square, T-shaped, or spiral.

[0041] The No. 5 electron gun scans the refining area, and the No. 5 electron gun scans the refining area in a serpentine continuous return scanning trajectory, such as Figure 3 As shown; The No. 6 and No. 7 electron guns scan the crystallization area. The two electron guns use concentric circle scanning trajectories that can be contracted and expanded. The No. 6 electron gun is the inner circle and the No. 7 electron gun is the outer circle, which fully covers the crystallization area.

[0042] ⑤The titanium alloy raw materials are smelted, refined, solidified in the crystallizer and then pulled out by the ingot pulling system to form an ingot.

[0043] ⑥ After the ingot is cooled and taken out of the furnace, the ingot bottom lead is cut off, and the riser flash is turned off to obtain a diameter of 650mm.

[0044] Step 5: VAR smelting: ① The ingot that has been smelted by EB is turned around and loaded into the VAR furnace for secondary smelting.

[0045] ②During VAR smelting, the diameter of the crystallizer is 720mm.

[0046] ③ The melting current is 26~31KA, the melting voltage is 30~35V, the arc stabilization current is AC, and the arc stabilization stirring time is 10~20 seconds; ④ The remaining 210-230 kg is smelted for shrinkage feeding. After smelting is completed, it is cooled with argon and taken out of the furnace after cooling for 8 hours.

[0047] Step 6: Machining and riser flaw detection: Use an ingot peeling lathe to turn the ingot surface to obtain a finished ingot. The single-side peeling amount is 4 to 7 mm. Figure 4 As shown, chip-shaped and block-shaped analysis samples were taken from five locations on the side surface of the ingot, namely the head H, upper TOP, middle M, lower B, and bottom Tail, and the chemical composition analysis was performed as shown in Table 1.

[0048]

[0049] Ultrasonic testing is used to determine the defect location at the riser, and a sawing machine is used to cut off the riser, such as Figure 5 As shown in Table 2, the composition analysis of nine sampling points on the riser transverse direction is as follows:

[0050] The same as Figure 5 As shown, the lateral component analysis of the ingot bottom is shown in Table 3:

[0051] Through the above sampling and analysis, it can be seen that the main elements of the ingot are evenly distributed and meet the requirements of relevant standards. The content of impurity elements also meets the requirements of relevant standards and is relatively evenly distributed. According to the characteristics of the round crucible, the energy distribution in the crucible can be adjusted by methods such as graphic superposition and energy distribution curve. Taking the center of the crucible as the reference point, the energy distribution near the edge of the crucible is preferably controlled to be 2 to 10 times. At the same time, the energy in the crucible is gradually reduced from the inside of the crucible to the center, reducing the temperature gradient, making the molten pool temperature basically uniform, achieving uniform crystallization, and ensuring composition uniformity; through reasonable energy distribution, a large amount of alloy volatilization can be avoided, and the influence on the composition uniformity of the ingot can be avoided.

[0052] As an improvement in the implementation method of process control in two smeltings: LIBS real-time composition analysis during EB melting process: System integration and installation: The system is installed above the EB furnace with a LIBS system with a high temperature resistant optical window, allowing the laser to safely penetrate and analyze the surface of the molten pool. During laser transmission, optical fiber is used to transmit high-energy pulsed laser from the safe area in the control room to the optical window above the molten pool. A highly sensitive spectrometer is set near the optical window to capture the plasma emission spectrum generated by laser excitation.

[0053] In order to allow the laser to enter and the plasma light to exit, an optical window is set at the front end of the probe. This window needs to be made of a material that is resistant to high temperatures and has good light transmittance, such as sapphire glass, which can remain transparent at high temperatures and has good mechanical strength.

[0054] Real-time monitoring and adjustment process: During the smelting process: Shortly after the smelting begins, the LIBS system is automatically triggered at regular intervals to perform composition analysis on the molten pool surface.

[0055]

[0056] During actual EB smelting, based on the LIBS data of the entire smelting cycle, experience is summarized to provide more accurate ingredient guidance for subsequent batches of smelting, and gradual optimization is performed. During actual use, based on the analysis values ​​of each smelting process, if the composition deviation is found, the stirring of the EB furnace molten pool can be controlled to increase to improve the uniformity of the ingot elements.

[0057] LIBS composition analysis during VAR smelting: System integration and installation: In VAR smelting, a LIBS probe is set in the gap between the upper side of the consumable electrode and the crucible in the VAR furnace. It uses a holographic grating spectrometer to analyze the composition of the upper layer of the molten pool during the melting and casting process. The LIBS probe is not detected by contact, it is a non-contact detection. This technology is based on the use of high-energy pulsed lasers focused on a point on the surface of the sample, and the high temperature generated by the laser pulse causes the sample to be locally vaporized and plasma to form. When the plasma cools, it emits characteristic spectra, which can be analyzed to determine the elemental composition present in the sample.

[0058] Since the LIBS process requires only a very small amount of sample material to generate the plasma, and the laser can be aimed at the target sample from a distance, it can perform elemental analysis without directly contacting the sample.

[0059] During the melting process: At the end of each melt, the top of the newly formed ingot is analyzed by LIBS in real time to confirm that the composition is as expected. If any deviations are found, adjustments can be made before the next melt begins, changing the melting current or adding specific alloying elements to make the ingot meet the requirements.

[0060]

[0061] Through the above examples, it can be seen that LIBS technology can not only realize real-time composition monitoring during the smelting process, but also timely discover problems and correct them in the next batch of smelting ingots, provide more accurate batching guidance for subsequent batches of smelting, and gradually optimize, thereby improving the yield and product quality. In practical applications, it is also necessary to continuously accumulate experience and optimize parameters to achieve the best results.

[0062] 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 method for preparing TC4 titanium alloy ingots with high recovery ratio and high uniformity, characterized in that: The following steps are involved: Step 1: Material frame preparation, selecting appropriate titanium alloy plate-shaped materials and welding them into material frames, wherein the titanium alloy plate-shaped materials are new materials or recycled materials, and one or more material frames are arranged in the material box of the EB furnace; the material frame comprises a bottom plate and a surrounding plate, and the surrounding plates are arranged around the bottom plate to form a material frame with an open top; Step 2: Preparation of recycled materials. Classify the recycled titanium alloy blocks according to the brand and the same composition standard, and clean the recycled titanium alloy materials of each classification, clean the surface oxide layer, oil stains and dirt, and take samples of the recycled materials for chemical composition analysis as the basis for subsequent batching, including the cleaning of the material frame; Step 3: Electrode briquetting: The chemical composition analysis results of the recycled materials are used as the calculation basis, and the volatilization loss of the aluminum element is taken into consideration. The remaining part is added in the form of sponge titanium + master alloy. The sponge titanium, AlV65 master alloy and aluminum beans are mixed in a fully automatic mixing equipment, and then pressed into electrode briquetting by a hydraulic press; Step 4: Laying the materials, arranging the electrode blocks in the middle of the material frame along the length direction, stacking the recycled titanium alloy blocks of the same composition in the material frame in an offset manner, and using small-sized gap fillers to fill the gaps between the irregular titanium alloy blocks to make the feed composition uniform; Step 5: Electron beam cold bed melting, the material frames are stacked into the material box of the feeder in sequence, and sent to the electron beam cold bed furnace for melting. After one melting, a titanium alloy ingot suitable for subsequent VAR melting is obtained, and the ingot is surface treated; Step 6: VAR smelting: The ingot smelted in step 5 is placed in a VAR furnace for secondary smelting.

2. The method for preparing a TC4 titanium alloy ingot with high recovery ratio and high uniformity according to claim 1, characterized in that: The preparation of recycled materials also includes the treatment of block materials, which are washed with acid and alkali, cleaned, and dried for later use; The process also includes the processing of chips, which are crushed by a crusher to form gap filling materials, which are then washed with high-pressure hot water, dried, and magnetically separated for standby use.

3. The method for preparing a TC4 titanium alloy ingot with high recovery ratio and high uniformity according to claim 1, characterized in that: The gap filling material includes small particles or powdered titanium alloy material, or sponge titanium, or specially customized titanium alloy particles of different particle sizes.

4. The method for preparing a TC4 titanium alloy ingot with high recovery ratio and high uniformity according to claim 1, characterized in that: The arrangement of the recycled materials in the material frame in step 4 includes the following methods: Step 41: Using a layered loading method, first lay the electrode blocks along the length of the material box, place them in the middle of the cross section of the material box, lay large blocks on both sides, and then sprinkle a layer of small particles or powder gap filler on them to fill the gaps between the large blocks, and then continue to lay large blocks, and repeat this process until the material frame is full; Step 42: During the layered loading process, a vibration device is used to vibrate the material frame so that the gap filling material fills the gaps between the large blocks of material, thereby further reducing the gaps between the recycled blocks of material; Step 43: Before loading into the EB furnace, pre-press the recycled material in the material frame from the top open side to form a tighter block and reduce the gap during loading.

5. The method for preparing a TC4 titanium alloy ingot with high recovery ratio and high uniformity according to claim 1, characterized in that: The step 5 specifically includes the following steps: Step 51: Load the loaded material frame into the horizontal feeding chamber of the EB furnace, close the feeding chamber, close the smelting chamber and lock it, and start the vacuum pumps of each level in turn to evacuate the furnace chamber; Step 52: Push the titanium alloy raw material in the material frame horizontally into an area within the electron beam cooling bed where the electron gun can scan; Step 53: When the vacuum degree reaches the melting requirement, set the scanning parameters of electron guns 1 to 7 and start preheating the electron guns; Step 54: respectively start the electron guns No. 1 to No. 4 in the melting area, the electron gun No. 5 in the refining area, and the electron guns No. 6 to No. 7 in the crystallization area, and perform scanning according to the scanning mode set for each electron gun; Step 55: The titanium alloy raw material is smelted, refined, and solidified in a crystallizer, and then pulled out by an ingot pulling system to form an ingot. The ingot pulling speed during the ingot pulling process is 8-11 mm / min. Step 56: After the ingot is cooled and taken out of the furnace, the surface of the ingot is finished, including cutting off the ingot bottom starter and turning off the riser flash to obtain a primary ingot with a diameter of 650 mm or 720 mm.

6. The method for preparing a TC4 titanium alloy ingot with high recovery ratio and high uniformity according to claim 5, characterized in that: The No. 1 and No. 2 electron guns are arranged on the same side of the cooling bed in the smelting area, and the No. 3 and No. 4 electron guns are arranged on the other side of the cooling bed; the No. 1 to No. 4 electron guns all cover a rectangular scanning area according to a serpentine continuous return scanning trajectory, and the scanning area of ​​the No. 1 to No. 4 electron guns performs a full coverage scanning of the cooling bed; The No. 5 electron gun scans the refining area, and the No. 5 electron gun scans the refining area in a serpentine continuous return scanning trajectory; The No. 6 and No. 7 electron guns scan the crystallization area. The two electron guns use concentric scanning trajectories that can be contracted and expanded. The No. 6 electron gun is the inner circle and the No. 7 electron gun is the outer circle, so as to fully cover and scan the crystallization area. The current of electron guns 1 to 4 is 7 to 11A, the current of electron gun 5 is 5 to 7A, and the current of electron guns 6 and 7 is 5 to 7A.

7. The method for preparing a TC4 titanium alloy ingot with high recovery ratio and high uniformity according to claim 1, characterized in that: During the VAR smelting, the diameter of the crystallizer is 720mm or 800mm; the smelting current is 26-31KA, the smelting voltage is 30-35V, the arc stabilization current is AC, and the arc stabilization stirring time is 10-20 seconds; the remaining 210-230Kg of smelting is used for shrinkage feeding, and after the smelting is completed, argon is filled for cooling, and the smelting is removed from the furnace after cooling for 8 hours.

8. The method for preparing a TC4 titanium alloy ingot with high recovery ratio and high uniformity according to claim 1, characterized in that: In the primary smelting and / or the secondary smelting, an online analysis device is used to monitor the elemental composition of the melt in real time. The online analysis device is a laser induced breakdown spectroscopy detection device.

9. The method for preparing a TC4 titanium alloy ingot with high recovery ratio and high uniformity according to claim 8, characterized in that: In the EB furnace, a detection window formed by one or more optical windows is set above the molten pool of the cooling hearth furnace to allow the laser to pass through and collect the plasma emission spectrum generated by the laser-induced breakdown spectroscopy. A holographic grating spectrometer is used to quickly analyze the spectral information from the plasma and determine the actual concentration of each element in the melt.

10. The method for preparing a TC4 titanium alloy ingot with high recovery ratio and high uniformity according to claim 8, characterized in that: In VAR smelting, a LIBS probe is installed in the gap between the upper side of the consumable electrode and the crucible in the VAR furnace, which uses a holographic grating spectrometer to perform composition analysis on the upper layer of the molten pool during the melting and casting process.

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