A method for recovering and remelting aluminum-titanium alloy chips

Abstract

A method for recovering and remelting aluminum-titanium alloy chips relates to the technical field of alloy chip recovery and remelting, and the method comprises the following steps: adopting the method of "Al plate or Al bean + alloy chips" and utilizing the method of "hot cathode electron beam cold hearth melting furnace + cold cathode electron beam cold hearth melting furnace" to complete the recovery and remelting of alloy chips; treating the alloy chips, washing, drying, crushing and magnetic separation; loading into a rotary feeder; smelting in a hot cathode electron beam cold hearth melting furnace; quality inspection; sawing according to composition and size requirements; preparing for packaging; smelting in a cold cathode electron beam cold hearth melting furnace; quality inspection; and storage of finished products. The beneficial effects of the present invention are: solving the problem that the traditional smelting method cannot melt back a large amount of titanium alloy chips, and the titanium alloy ingots obtained by smelting by the "hot cathode electron beam cold hearth melting furnace + cold cathode electron beam cold hearth melting furnace" method have good uniformity of alloy element distribution, high cleanliness and excellent metallurgical quality, which meet the requirements of national standards GB / T 3620.1~2016 and GB / T 5193~2007 for alloy recovery.

Description

Technical Field

[0001] The invention relates to the technical field of alloy chip recovery and remelting, and in particular to a method for recovering and remelting aluminum-titanium alloy chips. Background Art

[0002] With the rapid development of industries such as aerospace, high-end manufacturing, and chemicals, my country's manufacturing industry is paying more and more attention to lightweight and highly plastic titanium products. The pollution caused by the production of traditional materials such as aluminum products and steel products is particularly valued. Therefore, the development priority of the titanium industry is getting higher and higher. As a material with great potential, titanium has high activity, low thermal conductivity, high deformation resistance, and poor plasticity at room temperature. During the deformation process, it is not only easy to bond with the mold, but also causes a large amount of waste titanium chips to be produced in the manufacture of standard structural parts. How to use the large amount of titanium chips generated in the titanium production process, turn titanium chips into "waste" and achieve efficient utilization has become an important research topic in the titanium processing industry. This is of great significance to expanding the use of titanium materials, reducing costs, ensuring the needs of national defense science and technology industry construction, and promoting the sustainable development of my country's titanium industry.

[0003] In the process of industrial production of titanium and titanium alloy processing materials in my country, China has gradually begun to pay attention to the recycling of titanium alloy chips, and promulgated and implemented the standards for titanium and titanium alloy waste (GB / T29027-2007), which standardized the recycling process of titanium chips. Despite this, the recycling rate of titanium alloy chips in my country is still not high, with only about 10% of titanium alloy chips being recycled. The main reason for this low recycling rate is that the existing smelting method cannot solve the technical barriers of titanium alloy chip suppression, making it impossible to recycle a large amount of titanium alloy chips in time, which also leads to the high cost of titanium materials.

[0004] At present, a large amount of titanium alloy chips are basically stored in the warehouses of various companies. The amount that can be recycled by the traditional consumable arc furnace (VAR) smelting method is very low. At present, the main recycling method of traditional titanium alloy chips is: using the traditional vacuum consumable arc (VAR) furnace smelting method to recycle titanium chips. Take TC4 alloy as an example: the process is to mix sponge titanium (80%), titanium alloy chips (10%), aluminum vanadium master alloy, aluminum beans, titanium dioxide powder, iron nails and other raw materials and press them into electrode blocks, weld the pressed electrode blocks into "round rod-shaped" consumable electrodes, and then vacuum melt them into ingots in a VAR furnace;

[0005] At present, there are the following problems in recycling: Problem 1: When recycling titanium alloy chips by vacuum consumable arc (VAR) melting method, if the proportion of alloy chips exceeds 10%, it cannot be pressed into electrode blocks, and the recovery rate is particularly low; because the vacuum consumable furnace has no refining and impurity removal capabilities, the high and low density inclusions of titanium alloy chips cannot be effectively removed, which ultimately affects the quality of the ingot;

[0006] Question 2: The vacuum degree of the VAR melting furnace is generally 0.1-1.0 Pa, and the furnace chamber space is small and the escape gap for gas impurities is limited, so the degassing effect is poor. The titanium alloy chips themselves carry a large amount of gas, and these gas impurities cannot be removed, which will increase the gas content in the ingot. Summary of the invention

[0007] In view of the shortcomings of the prior art, the present invention provides a method for recycling and remelting aluminum-titanium alloy chips. Without briquetting the chips, the method of "Al plate or Al bean + alloy chips" is adopted, and the method of "hot cathode electron beam cold hearth melting furnace + cold cathode electron beam cold hearth melting furnace" is utilized to complete the recycling and remelting of the alloy chips, so as to solve the problems that the alloy chips cannot be pressed into shape and the recycling efficiency is low.

[0008] The present invention provides a method for recycling and remelting aluminum-titanium alloy chips, which comprises the following steps:

[0009] Alloy scrap material processing: cleaning, drying, crushing, magnetic separation → loading into rotary feeder → melting in hot cathode electron beam cold hearth melting furnace → quality inspection → sawing according to composition and size requirements → preparation and packaging → melting in cold cathode electron beam cold hearth melting furnace → quality inspection → finished product storage;

[0010] The specific steps include:

[0011] Step 1: Through the titanium alloy chip processing process, cleaning, drying, crushing, and magnetic separation, the smelting requirements of the hot cathode electron beam cold hearth smelting furnace are met;

[0012] Step 2: weigh the titanium alloy chips processed in step 1 and load them into the rotary feeder to be melted;

[0013] Step 3: feeding the titanium alloy chips in the rotary feeder in step 2 into a hot cathode electron beam cold hearth melting furnace for melting to obtain a corresponding titanium alloy ingot;

[0014] Step 4: Conduct chemical composition testing on the ingot obtained in step 3;

[0015] Step 5: sawing the ingot obtained in step 3 according to the chemical composition test results in step 4;

[0016] Step 6: Determine the amount of raw materials used for the aluminum-titanium alloy and weigh them;

[0017] Step 7: Pack the raw materials in steps 5 and 6 into boxes;

[0018] Step 8: placing the material block prepared in step 7 in a cold cathode electron beam cold hearth melting furnace for melting to obtain a titanium alloy ingot;

[0019] Step 9: Perform surface machining and chemical composition testing on the ingot obtained in step 8.

[0020] The beneficial effects of the present invention are: 1. It solves the problem that the prior art cannot recycle aluminum-titanium alloy chips in large quantities, and can 100% recycle aluminum-titanium alloy chips of various grades;

[0021] 2. The molten pool of the ingot melted in the hot cathode electron beam cold hearth melting furnace plus the cold cathode electron beam cold hearth melting furnace is very shallow (about ≤100mm), while the molten pool depth of the VAR melting furnace is positively proportional to the ingot diameter (generally greater than the ingot radius). The molten pool depth becomes shallower and the electron beam continuously bombards the molten pool liquid surface, which can significantly improve the solidification segregation of the ingot.

[0022] 3. The high and low density inclusions in the titanium alloy chips are effectively removed, and the cleanliness of the ingot is guaranteed to the maximum extent. The metallurgical quality of the final ingot is better than that of the ingot produced by VAR (multiple) smelting. The obtained titanium alloy ingot has good uniformity of alloy element distribution, high cleanliness and excellent metallurgical quality, which meets the requirements of national standards GB / T 3620.1~2016 and GB / T 5193~2007. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 is a process flow chart of the present invention;

[0024] Figure 2 This is the fitting curve of the 1# electron gun current in the cold cathode electron beam cold bed melting furnace process;

[0025] Figure 3 This is the fitting curve of the 2# electron gun current in the cold cathode electron beam cold bed melting furnace process;

[0026] Figure 4 This is the fitting curve of the 3# electron gun current in the cold cathode electron beam cold bed melting furnace process;

[0027] Figure 5 This is the fitting curve of the 4# electron gun current in the cold cathode electron beam cold bed melting furnace process;

[0028] Figure 6 This is the fitting curve of the 5# electron gun current in the cold cathode electron beam cold bed melting furnace process;

[0029] Figure 7 This is the fitting curve of the 6# electron gun current in the cold cathode electron beam cold bed melting furnace process;

[0030] Figure 8 This is the fitting curve of the 7# electron gun current in the cold cathode electron beam cold bed melting furnace process;

[0031] Fig. 9This is the fitting curve of the feed rate in the cold cathode electron beam cold hearth melting furnace process. DETAILED DESCRIPTION

[0032] Example 1

[0033] according to Figures 2 to 9 The figure shows the process parameter record in the cold cathode electron beam cold hearth melting furnace containing aluminum-titanium alloy. The present invention provides a method for recycling and remelting aluminum-titanium alloy scraps, and the specific method includes:

[0034] Step 1: Processing of titanium alloy chips

[0035] The hot cathode electron beam cold hearth melting furnace is equipped with an Archimedes screw feeder, which meets the requirements of continuous loading of alloy chips for continuous melting. However, due to the low stacking density and poor cleanliness of the alloy chips, the alloy chips must be processed. The processing process is as follows: cleaning, drying, crushing, and magnetic separation; the surface of the chips after processing has no obvious oxidation and oil stains, the length of the chips is ≤10mm, and the stacking density of the chips is ≥0.8g / cm3 (a single barrel of the Archimedes screw feeder can hold 1t of alloy chips);

[0036] Step 2: Alloy chips are loaded into barrels

[0037] Add the alloy chips processed in step 1 into the silo of the mixer, and add them to the Archimedean screw feeder through a belt conveyor by weighing the materials. The amount of alloy chips loaded in a single barrel shall not be less than 1 t;

[0038] Step 3: Hot cathode electron beam cold hearth melting furnace melting

[0039] The Archimedean rotary feeder loaded with alloy chips in step 2 is hoisted and placed into the feeding chamber of the electron beam cooling hearth furnace, and the alloy chips are sent to the hot cathode electron beam cooling hearth furnace for smelting to obtain titanium alloy ingots. The vacuum degree in the hot cathode electron beam cooling hearth furnace is higher than 4.0×10 -3 hpa, use helium mass spectrometer leak detector to check the furnace body for leaks, the furnace body leakage rate should be less than 3.3hpa·l / s;

[0040] Furthermore, the step 3 of hot cathode electron beam cold hearth melting furnace comprises the following steps:

[0041] Step 31: Check the hot cathode electron beam cooling furnace, including: check the isolation valves and cameras of each observation window, check the cooling water of the power cabinet, check the isolation valve of the ingot pulling chamber, and check the plunger valve of the rotary feeding device;

[0042] Step 32: After checking the hot cathode electron beam cooling furnace in step 31, start the hot cathode electron gun, set the power values ​​of electron guns 1 to 6, and record them;

[0043] Step 33: After the electron guns No. 1 to No. 6 are started in step 32, the power values ​​of the electron guns are set again. After the power values ​​of the electron guns are set, the Archimedean rotary feeding device is started for smelting. During the smelting period, it is ensured that each electron gun operates normally;

[0044] Step 34: After the smelting in step 33 is completed, the obtained ingot is taken out from the hot cathode electron beam furnace ingot pulling system and the composition is tested;

[0045] Further, the step 33 includes the following steps:

[0046] Step 331: Reasonably select hot cathode electron beam cold bed melting process parameters, the upper focus setting value of each electron gun is 75%, the lower focus setting value is 65%, and the DK value (the distance between the cathode and the anode) is 0<DK<97%;

[0047] Step 332: The smelting speed can be selected from 700kg / h to 900kg / h, and the corresponding feeding speed is 5 shakes / minute;

[0048] Step 4: Hot cathode electron gun cold bed smelting to obtain ingot composition detection

[0049] The composition of the ingot obtained by hot cathode electron beam cold bed melting in step 3 is tested. First, the AB edge and CD edge of the ingot are obtained by a planer and miller to obtain a sampling prism. Then, ring samples and chip samples are taken every 200 mm on the two prisms (each sample is packed with kraft paper and marked), and finally sent to the laboratory for composition testing;

[0050] Step 5: Hot cathode electron gun cooling bed melting ingot sawing into blocks

[0051] According to the chemical composition test results in step 4 and the material specification and size requirements of the cold cathode electron beam cold hearth melting furnace, the ingot obtained by hot cathode electron beam cold hearth melting is sawed into blocks;

[0052] Step 6: Packing of block ingredients

[0053] Taking the ingot melted from TC4 titanium alloy scraps as an example, the percentage of metal materials required for cold cathode electron beam melting raw material ingredients is: 95% to 98% of the sawn block material in step 5, 1.1% to 2% of the aluminum plate; weigh a total of 9500kg of raw materials according to the above proportions and store them separately;

[0054] Furthermore, the purity of the aluminum plate in step 6 is greater than 99.6%;

[0055] The components of the sawn block are as follows: O content is 1.5wt%, N content is 0.045wt%, Fe content is 0.18wt%, C content is 0.05wt%, H content is 0.001wt%, Al content is 4.85% to 5.1%, and V content is 3.5% to 4.5%;

[0056] The above materials are evenly stacked in the material box of the cold cathode electron beam cold bed melting furnace based on the concept of macroscopic uniformity, and the total weight of the material blocks is weighed using an electronic crane scale and recorded;

[0057] Step 7: Cold cathode electron beam cold hearth melting furnace melting

[0058] The material box filled with materials in step 6 is sent to a cold cathode electron beam cold hearth melting furnace for melting to obtain a TC4 titanium alloy ingot. The vacuum degree in the cold cathode electron beam cold hearth melting furnace is higher than 5.0×10 -3 Torr, use a helium mass spectrometer leak detector to check the furnace for leaks, and the furnace leakage rate should be less than 3.3 Torr·l / s;

[0059] Furthermore, the electron beam cold hearth furnace smelting in step 7 comprises the following steps:

[0060] Step 71: Place the material blocks pressed in step 6 in a double layer in a material box, one block per row; the first row is the first row of material blocks, followed by the normal smelting material blocks, and the last row is the tail row of material blocks;

[0061] Step 72: Check the electron beam cooling furnace, including: checking the filling hydrogen and oxygen gas pressure, checking the cooling water of the power cabinet, turning on the power cabinet and setting the voltage of the power cabinet;

[0062] Step 73: After checking the electron beam cooling furnace in step 72, start the electron beam cooling furnace, start the 1#, 2#, 3#, 4#, 5#, 6#, 7# electron guns respectively, set the current values ​​of the 1# to 7# electron guns, and record them;

[0063] Step 74: After the 1# to 7# electron guns are started in step 73, the current values ​​of the electron guns are set again. After the current values ​​of the electron guns are set, the material is pushed for smelting. During the smelting period, it is ensured that there is no cold zone in the cooling bed;

[0064] Step 75: After the smelting in step 74 is completed, the obtained ingot is taken out from the ingot pulling system of the EB furnace, and the surface of the ingot is processed (removing the oxide scale and performing a "flat head" treatment on the end surface of the ingot);

[0065] Further, step 72 includes: checking that the filling hydrogen and oxygen gas pressure is sufficient, confirming that the oxygen regulating valve switch valve is in a closed state, and closing the fine-tuning valve by 1 / 5 to 1 / 4 turn from the position in the previous furnace smelting to ensure that O 2The initial input amount will not cause oxidation on the cathode surface of the electron gun. Check that the cooling water of the power cabinet is correct, turn on the power cabinet, and set the voltage of the power cabinet to 30KV;

[0066] Further, the step 73 includes the following steps:

[0067] Step 731: Start the 1#, 2#, 3#, 4#, and 5# electron guns to melt the surface of the condensate shell in the cooling bed. During the startup process, the scanning track area is continuously expanded as the current of each gun increases to avoid local overheating of the condensate shell.

[0068] Step 732: Start the 6# and 7# electron guns at the same time, adjust the scanning trajectory as the current increases, and increase the current to heat the bottom support of the ingot in the crystallizer to avoid quenching and splashing when the alloy liquid flows in, thereby causing the crystal quality of the bottom of the ingot to deteriorate, and record the current values ​​of the 6# and 7# electron guns at this time;

[0069] Step 733: Control the rhythm of starting the electron gun to synchronize the melting of the shell surface with the heating of the bottom support of the ingot in the crystallizer as much as possible;

[0070] Furthermore, during the normal smelting described in step 74, the 1# to 4# electron guns ensure that the material is melted normally, the 5# electron gun ensures that the material flows from the cooling bed into the crystallizer through the runner, and the 6# and 7# electron guns melt the entire surface of the molten pool in the crystallizer. The power obtained in the material melting zone (1# to 4# electron guns) accounts for 65% to 70% of the total power, the power in the refining zone (5# electron gun) accounts for 10% to 15%, and the power in the crystallization zone (6# and 7# electron guns) accounts for 25% to 20%;

[0071] When pushing the material in step 74, keep the feeding speed of the feeder stable and complete the smelting as much as possible according to the set value; after the material block is melted, turn off the 1# to 7# electron guns immediately;

[0072] Furthermore, the EB smelting process parameters are reasonably selected. Under different raw material batching values, different process parameters are selected to achieve the requirements of stable smelting and preparation of qualified aluminum-titanium alloy ingots. The specific steps are as follows:

[0073] Step 741: EB smelting is a "semi-continuous" smelting process of "melting and solidifying at the same time", and the feed rate in the feeder can be selected from 10mm / min to 16mm / min;

[0074] Step 742: The smelting speed can be selected to be 750kg / h to 800kg / h, and the corresponding ingot pulling speed is 3mm / min to 4mm / min.

Claims

1. A method for recovering and remelting aluminum-titanium alloy chips, Features: Aluminum and alloy scraps are used to remelt the aluminum and alloy scraps through a combined recovery method of a hot cathode electron beam cold hearth melting furnace and a cold cathode electron beam cold hearth melting furnace; the combined recovery method of the hot cathode electron beam cold hearth melting furnace and the cold cathode electron beam cold hearth melting furnace specifically comprises the following steps: Step 1: Process the selected titanium alloy chips through the titanium alloy chip processing process to specifically meet the smelting requirements of the hot cathode electron beam cold hearth smelting furnace; Step 2: weigh the titanium alloy chips processed in step 1 and load them into the rotary feeder to be melted; Step 3: feeding the titanium alloy chips in the rotary feeder in step 2 into a hot cathode electron beam cold hearth melting furnace for melting to obtain a corresponding titanium alloy ingot; Step 4: Conduct chemical composition testing on the ingot obtained in step 3; Step 5: sawing the ingot obtained in step 3 according to the chemical composition test result in step 4 to obtain sawn blocks; Step 6: Determine the amount of raw materials used for aluminum-titanium alloy and weigh them; Step 7: Pack the raw materials in step 6 into boxes; Step 8: placing the material block prepared in step 7 in a cold cathode electron beam cold hearth melting furnace for melting to obtain a titanium alloy ingot; Step 9: Perform chemical composition testing and surface machining on the ingot obtained in step 8; The vacuum degree in the hot cathode electron beam cooling furnace in step 2 is higher than 4.0×10 -3 hpa; In step 8, the vacuum degree in the cold cathode electron beam cold hearth melting furnace is higher than 5.0×10 -3 Torr.

2. The method for recycling and remelting aluminum-titanium alloy chips according to claim 1, Features: The titanium alloy chip processing process in step 1 is cleaning, drying, crushing and magnetic separation.

3. The method for recycling and remelting aluminum-titanium alloy chips according to claim 1, Features: The raw materials used for the aluminum-titanium alloy in step 6 are the sawn blocks and aluminum plates described in step 5.

4. The method for recycling and remelting aluminum-titanium alloy chips according to claim 3, Features: The usage of the sawing block and the aluminum plate are respectively: 95% to 98% of the sawing block and 1.1% to 2% of the aluminum plate.

5. A method for recycling and remelting aluminum-titanium alloy chips according to claim 4, Features: The purity of the aluminum plate is greater than 99.6%.

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