Smelting preparation method of high-quality titanium alloy

Abstract

The invention provides a smelting preparation method of a high-quality titanium alloy, which comprises the following steps: (1) weighing raw materials, and uniformly mixing; (2) pressing into a consumable electrode block; (3) welding to obtain a consumable electrode; (4) polishing, drying and dehumidifying the flashes and the welding spots; (5) carrying out primary vacuum consumable smelting to obtain a primary ingot; (6) cleaning, head flattening, head and tail butt welding, polishing and head and tail turning are carried out, and then secondary vacuum consumable smelting is carried out, so that a secondary ingot is obtained; and (7) head flattening treatment is conducted, third-time vacuum consumable smelting is conducted after the head and the tail are turned, and the high-quality titanium alloy is obtained. According to the method, a direct-current stirring magnetic field (direct-current arc-stabilizing current) is applied in three times of vacuum consumable melting, so that a molten pool rotates and stirs in the same direction, and the component distribution of the titanium alloy cast ingot is more uniform; meanwhile, through the synergistic effect of three times of vacuum consumable smelting, the component uniformity and the yield of the titanium alloy cast ingot are improved; belongs to the technical field of titanium and titanium alloy material processing.

Description

Technical Field

[0001] The invention relates to the technical field of titanium and titanium alloy material processing, and in particular to a smelting preparation method for high-quality titanium alloy. Background Art

[0002] Titanium alloy refers to a variety of alloy metals made of titanium and other metals. It has been widely used in aerospace, shipbuilding, chemical, petroleum, automobile, medical, nuclear power and other fields due to its low density, high specific strength, good corrosion resistance, non-toxic and non-magnetic, good heat resistance, weldability, and good biocompatibility.

[0003] Vacuum consumable melting (VAR melting) is the most widely used titanium alloy ingot melting method in China. It has many advantages such as low power consumption, fast melting speed, and high quality reproducibility. The melting of TB13 titanium alloy ingots generally adopts three-stage vacuum consumable melting technology. However, titanium alloy ingots generally contain segregation elements, which are easily formed in local areas. The enriched component segregation is distributed in the form of scattered points inside the ingot, resulting in uneven composition of the obtained titanium alloy ingot and large differences in phase transition points in different parts, which brings safety and quality risks to the application of this titanium alloy.

[0004] In the process of preparing titanium alloy ingots by vacuum consumable smelting, if a lower smelting current is used, the depth of the molten pool can be reduced, and the component segregation of the ingot can be effectively controlled; however, smelting with a lower current is prone to shrinkage of the molten pool, unsatisfactory edge coverage, and subcutaneous pores on the surface of the ingot, which leads to an increase in the amount of surface peeling of the ingot and a decrease in the yield rate. If a higher smelting current is used, the molten pool will have a good edge coverage, but the depth of the molten pool will increase, which can easily lead to excessive shrinkage holes, increased sawing, and a decrease in the yield rate. Therefore, it is urgent to study a titanium alloy smelting preparation method that can reduce element segregation, improve component uniformity, and increase the yield rate. Summary of the invention

[0005] In order to solve the above technical problems, the technical solution adopted by the present invention is to provide a smelting preparation method for high-quality titanium alloy to solve the technical problems of enriched component segregation, uneven composition and low yield rate existing in the existing titanium alloy ingot smelting technology.

[0006] The embodiment of the present invention provides a smelting preparation method of high-quality titanium alloy, comprising the following steps:

[0007] (1) Weigh the raw materials of titanium alloy according to proportion and mix them evenly;

[0008] (2) Pressing the uniformly mixed raw materials into consumable electrode blocks;

[0009] (3) closely arranging and fixing the consumable electrode blocks, and welding them under vacuum conditions to obtain consumable electrodes;

[0010] (4) Grinding, drying and dehumidifying the flash and welding points of the consumable electrode;

[0011] (5) performing a first vacuum consumable melting on the consumable electrode after drying and dehumidification to obtain a primary ingot;

[0012] (6) The primary ingot is cleaned and flattened, butt-welded and polished under vacuum conditions, and then the head and tail are turned around and a second vacuum consumable smelting is performed to obtain a secondary ingot;

[0013] (7) The secondary ingot is flattened, and after the head and tail are turned over, a third vacuum consumable melting is performed to obtain a tertiary ingot, which is a high-quality titanium alloy.

[0014] Preferably, in step (1), the raw materials of the titanium alloy include sponge titanium and an intermediate alloy, and the weight percentage content of each element in the sponge titanium and the intermediate alloy is: Al: 3.60-4.10%, V: 21.0-22.0%, Fe≤0.09%, C≤0.025%, O≤0.10%, N≤0.010%, H≤0.010%, and the balance is Ti; wherein the particle size of the sponge titanium is 3.0-12.70 mm, and the Brinell hardness is ≤87.0 HB.

[0015] Preferably, in step (1), a mixing device is used to weigh the raw material of the titanium alloy, and a mixing tank is used to mix and stir the raw material of the titanium alloy for 1 to 2 minutes.

[0016] Preferably, in step (2), a hydraulic press is used to press the uniformly mixed raw materials into a consumable electrode block until the density of the consumable electrode block reaches 3.40 to 3.60 g / cm 3 .

[0017] Preferably, in step (3), the consumable electrode blocks are grouped in groups of 10 to 15 and welded in a vacuum plasma welding box. During welding, the vacuum is evacuated to ≤5.0 Pa, the gas leakage rate is ≤2.0 Pa / min, and argon is filled to a vacuum degree of 4×10 4 Pa, cooling after welding ≥1.0h, then out of the furnace.

[0018] Preferably, in step (4), the welding part of the consumable electrode is polished to the original color of the metal, and then placed in a drying furnace for drying and dehumidification treatment at 100-150° C. for not less than 12 hours.

[0019] Preferably, in step (5), the consumable electrode after drying and dehumidification is placed in a vacuum consumable furnace for vacuum consumable melting within 30 minutes, and the parameters of the first vacuum consumable melting are: vacuum degree ≤3.0Pa; leakage rate ≤0.8Pa / min; melting current is 2-15kA; arc stabilization current is DC 2.0-8.0A; melting rate is 4.0-15.0kg / min; cooling water temperature is maintained at 40°C or below; argon filling cooling time after melting is ≥4.0h.

[0020] Preferably, in step (6), a vacuum plasma welding box is used for head-to-tail welding, and the vacuum is evacuated to ≤5.0Pa during welding, and the leakage rate is ≤2.0Pa / min, and argon is filled to a vacuum degree of 4×10 4 Pa, cooling after welding ≥1.0h, then out of the furnace.

[0021] Preferably, in step (6), during the second vacuum consumable melting, the head of the primary ingot faces downward and the tail faces upward; the parameters of the second vacuum consumable melting are: vacuum degree ≤2.0Pa; leakage rate ≤0.80Pa / min; melting current 5-25kA; arc stabilization current adopts DC 2.0-10.0A; melting rate is 5.0-18.0kg / min; cooling water temperature is maintained at 45°C or below; argon filling cooling time after melting is ≥6.0h.

[0022] Preferably, in step (7), the parameters of the third vacuum consumable melting are: vacuum degree ≤1.0Pa; leakage rate ≤0.80Pa / min; melting current 8-24kA; arc stabilization current adopts DC 2.0-10.0A; melting rate is 5.0-18.0kg / min; cooling water temperature is maintained at 45°C or below; at the end of melting, when the weight of the consumable electrode is reserved at 200kg, the feeding stage is entered, and the feeding current is 0-10kA; and the argon filling cooling time after melting is ≥7.0h.

[0023] In step (1), when the raw materials of the titanium alloy are weighed by a mixing device, the sponge titanium is transported to the sponge titanium bin of the mixing device, and the intermediate alloy is transported to different alloy bins. Weighing hoppers are respectively provided at the bottom of the sponge titanium bin and the alloy bin. The weighing hoppers are controlled by the PLC control system of the mixing device to realize automatic weighing and feeding. After the raw materials are weighed, they are transported to the mixing tank by a feeding trolley for mixing and stirring for 1 to 2 minutes. The precision of the sponge titanium weighing hopper is ±10g, and the precision of the intermediate alloy weighing hopper is ±2g. The mixing device includes a mixer.

[0024] In step (3) and step (6), when a vacuum plasma welding box is used for welding, the purity of argon gas is 99.99%. Liquid argon is converted into gaseous state through a converter and is filled into the vacuum plasma welding box through the control of the welding box solenoid valve.

[0025] The present invention provides a smelting preparation method for high-quality titanium alloy. Compared with the prior art, the present invention has the following beneficial effects:

[0026] (1) The present invention adopts a mixing tank stirring and flipping mixing method, so that small particles of the material can be fully mixed with the sponge titanium, achieving full and uniform mixing of the material, ensuring the uniformity of the material to a great extent, avoiding the uneven distribution of various materials due to different particle sizes, and preliminarily improving the composition uniformity of the titanium alloy ingot.

[0027] (2) The present invention adopts a vacuum plasma welding box instead of manual welding, and welds in a closed environment filled with argon gas, thereby avoiding the influence of external gas elements and the occurrence of weld point oxidation, thereby improving the yield rate of titanium alloy ingots.

[0028] (3) The present invention applies a DC stirring magnetic field (DC arc stabilizing current) in the three vacuum consumable melting processes, so that the molten pool is rotated and stirred in the same direction, making the composition distribution of the titanium alloy ingot more uniform; at the same time, low current, low voltage and short arc melting are used in the first vacuum consumable melting, which is conducive to a stable molten pool. The molten pool of short arc melting is shallow and cools faster, thereby avoiding element segregation and improving the impurity removal and purification effect of the molten pool; high current and high voltage are used in the second vacuum consumable melting, so that the composition is further stirred evenly, and at the same time, violent melting is conducive to effective impurity removal; low current and low voltage are used in the third vacuum consumable melting, which is conducive to a stable molten pool, further improving the composition uniformity of the titanium alloy ingot, and can further remove impurities and improve the purity of the titanium alloy ingot; the three vacuum consumable melting processes work synergistically to improve the composition uniformity and yield rate of the titanium alloy ingot.

[0029] (4) The three vacuum consumable melting processes of the present invention all include an arc-starting melting stage and a stable melting stage. In the arc-starting melting stage, the current is gradually increased to heat the crucible and the consumable electrode before the molten droplets are generated, thereby shortening the time from the establishment of the molten pool to the completion of the molten pool and reducing the generation of cold shut at the bottom of the ingot. In the stable melting stage, the current is kept unchanged, the voltage is adjusted, and under the action of the DC stirring magnetic field, the arc is fully rotated to heat the edge of the molten pool to ensure that the molten pool has good edge-to-edge properties. At the same time, the molten pool is stable, thereby reducing the generation of internal defects in the ingot. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0031] Figure 1A schematic diagram of a consumable electrode block in Example 1 of the present application;

[0032] Figure 2 Schematic diagram of the microstructure of the high-quality titanium alloy prepared in Example 1 of the present application;

[0033] Figure 3 Schematic diagram of the sampling position of the high-quality titanium alloy prepared in Example 1 of the present application. DETAILED DESCRIPTION

[0034] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present application clearer, the present application is further described in detail in conjunction with the embodiments below. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application. The methods used in the present invention are conventional methods unless otherwise specified; the raw materials and devices used are conventional commercial products unless otherwise specified.

[0035] In order to verify the reliability of the effect of the present invention, the present invention is described below in conjunction with Examples 1 to 4, and compared with Comparative Examples 1 to 3.

[0036] Example 1

[0037] This embodiment provides a smelting preparation method for high-quality titanium alloy, comprising the following steps:

[0038] (1) Weigh the raw materials of titanium alloy in proportion. The weights of titanium sponge and master alloy are: 2409.10 kg titanium sponge, 805.20 kg vanadium aluminum master alloy (AlV85), 9.70 kg aluminum bean (Al99.7), and the total feed amount is 3224.0 kg;

[0039] Select titanium sponge of grade 1 or above, and conduct optical screening and magnetic separation on the titanium sponge to make the particle size of titanium sponge 3.0-12.70mm and the Brinell hardness ≤87.0HB;

[0040] The titanium sponge is transported to the titanium sponge bin of the mixer, and the vanadium-aluminum master alloy and aluminum beans are transported to different alloy bins. Weighing hoppers are respectively provided at the bottom of the titanium sponge bin and the alloy bin. The weighing hoppers are controlled by the PLC control system of the mixer to realize automatic weighing and feeding. After the raw materials are weighed, they are transported to the mixing tank by the feeding trolley and mixed and stirred for 1 to 2 minutes to make the raw materials evenly mixed.

[0041] (2) The mixed raw materials are transported to a hydraulic press to be pressed into consumable electrode blocks. After being taken out, the weight and size of the consumable electrode blocks are tested until the density of the consumable electrode blocks reaches 3.40 to 3.60 g / cm 3 .

[0042] In this embodiment, there are 26 consumable electrode blocks in total, and their specifications are shown in Table 1 and Figure 1 As shown, it is found through calculation that its density meets the requirements.

[0043] Table 1 Specifications of consumable electrode blocks

[0044] Weight(kg) Height(mm) Height(mm) Width(mm) 124 369 369 196

[0045] (3) The consumable electrode blocks are grouped into 13 blocks, and the 13 consumable electrode blocks are closely arranged. The consumable electrode blocks are fixed by a hoisting material rack, and then the consumable electrode blocks and the hoisting material rack are placed in a vacuum plasma welding box for welding to obtain consumable electrodes;

[0046] During welding, the vacuum is evacuated to ≤5.0Pa, the leakage rate is ≤2.0Pa / min, and the argon gas is filled to a vacuum degree of 4×10 4 After Pa, welding begins. After welding, cooling is ≥1.0h and then the furnace is taken out.

[0047] The other group of 13 consumable electrode blocks are operated in the same way.

[0048] (4) The flash and welding point of the consumable electrode are polished to the original color of the metal. After polishing, it is placed in a drying furnace at 100-150°C for no less than 12 hours for drying and dehumidification.

[0049] (5) Within 30 minutes, the consumable electrode after drying and dehumidification is placed in a vacuum consumable furnace using a Ø470 mm crucible for the first vacuum consumable melting, and cooled to obtain two primary ingots;

[0050] Among them, the parameters of the first vacuum consumable melting are: vacuum degree ≤3.0Pa, leakage rate ≤0.80Pa / min, first use 2~4kA current to strike the arc, keep it for 5min to preheat the crucible, and after successful arc striking, increase the melting current to 14~15kA within 10min, and start arc melting for 20min; then reduce the melting current to 13~14kA within 5min, and control the vacuum degree below 3.0Pa, the melting voltage is 20~44V, the arc stabilization current uses DC 2.0~8.0A, the melting rate is 4.0~15.0kg / min, the cooling water temperature is kept at 40℃ or below, and the argon filling cooling time after melting is ≥4.0h.

[0051] (6) The two primary ingots are cleaned and flattened, and then the two primary ingots are butt-welded in a vacuum plasma welding box. After cooling, the welded parts are polished. The welded primary ingots are then turned head-to-tail using a Φ560 mm crucible and placed in a vacuum consumable furnace for a second vacuum consumable smelting, with the head of the primary ingot facing downward and the tail facing upward. After smelting, the primary ingots are cooled to obtain secondary ingots;

[0052] The parameters of head-to-tail welding are: vacuuming to ≤5.0Pa during welding, gas leakage rate ≤2.0Pa / min, filling with argon gas to a vacuum degree of 4×10 4 Pa, cooling after welding ≥1.0h, out of the furnace;

[0053] The parameters of the second vacuum consumable melting are: vacuum degree ≤2.0Pa, leakage rate ≤0.80Pa / min, first use 2~4kA current to strike the arc, keep it for 5min to preheat the crucible, and after successful arc striking, increase the melting current to 14~25kA within 10min, and control the vacuum degree below 2.0Pa, the melting voltage is 22~44V, the arc stabilization current is DC 2.0~10.0A, the melting rate is 5.0~18.0kg / min, the cooling water temperature is kept at 45℃ or below, and the argon cooling time after melting is ≥6.0h.

[0054] (7) Flatten the secondary ingot, then turn it over so that the tail of the secondary ingot faces upward and the head faces downward, put it into a vacuum consumable furnace in a 620 mm crucible for the third vacuum consumable smelting, and cool it to obtain a tertiary ingot, which is a high-quality titanium alloy;

[0055] Among them, the parameters of the third vacuum consumable melting are: vacuum degree ≤1.0Pa, leakage rate ≤0.80Pa / min, first use 2~4kA current to strike the arc, keep it for 5min to preheat the crucible, and after successful arc striking, increase the melting current to 16~24kA within 10min, and control the vacuum degree below 2.0Pa, the melting voltage is 22~44V, the arc stabilization current is DC 2.0~10.0A, and the melting rate is 5.0~18.0kg / min; the cooling water temperature is maintained at 45℃ or below, and the argon cooling time after melting is ≥7.0h.

[0056] Example 2

[0057] The difference between this embodiment and Example 1 is that in step (1), the content of Al element is reduced from 4.0% to 3.90%, and the content of other elements remains unchanged. The other operations are the same, and finally a high-quality titanium alloy is obtained.

[0058] Example 3

[0059] The difference between this embodiment and Example 1 is that in step (1), the content of the V element is reduced from 21.50% to 21.25%, and the content of other elements remains unchanged. The other operations are the same, and finally a high-quality titanium alloy is obtained.

[0060] Example 4

[0061] The difference between the present embodiment and Example 1 is that in step (1), the content of the Fe element is changed from Fe≤0.09% to Fe≤0.07%, and the content of the O element is changed from O≤0.10% to O≤0.08%, and the content of the other elements remains unchanged. The other operations are the same, and finally a high-quality titanium alloy is obtained.

[0062] Comparative Example 1

[0063] The difference between the present embodiment and Example 1 is that in step (3) and step (6), the vacuum plasma welding box welding is changed to manual platform welding, and the remaining operations are the same, and finally a titanium alloy is obtained.

[0064] Comparative Example 2

[0065] The difference between the present embodiment and Example 1 is that in steps (5) to (7), the DC stirring magnetic field of the three vacuum consumable melting processes is changed to an AC stirring magnetic field, and the remaining operations are the same, and a titanium alloy is finally obtained.

[0066] Comparative Example 3

[0067] The difference between the present embodiment and Example 1 is that in steps (5) to (7), the DC stirring magnetic field of the three vacuum consumable melting processes is changed to no stirring magnetic field, and the remaining operations are the same, and a titanium alloy is finally obtained.

[0068] It should be noted that: in the above-mentioned embodiments 1 to 4 and comparative examples 1 to 3, in step (1), the precision of the titanium sponge weighing hopper is ±10g, and the precision of the intermediate alloy weighing hopper is ±2g. In step (2), since the hydraulic press prevents the mold from tilting during the pressing process, resulting in inconsistent heights at both ends of the pressed consumable electrode block, two height dimensions are required to determine its density. In steps (3) and (6), when a vacuum plasma welding box is used for welding, the purity of argon is 99.99%, and the liquid argon is converted into gaseous state through a converter and is filled into the vacuum plasma welding box through the control of the welding box solenoid valve.

[0069] The high-quality titanium alloy prepared in Example 1 was tested, and its microstructure was measured as follows: Figure 2 As shown. Figure 2 It can be seen that the low-magnification metallographic elements of the cross-section of the titanium alloy ingot are evenly distributed.

[0070] In order to verify the effect of the present invention, samples were taken from the high-quality titanium alloys of Examples 1 to 4 and the titanium alloys of Comparative Examples 1 to 3 to detect the components of different parts thereof.

[0071] Sampling location: Five sampling locations such as Figure 3As shown, the left side is the head and the right side is the tail, which are respectively 200 to 300 mm away from the head and tail of the titanium alloy ingot, the middle position of the titanium alloy ingot, and the middle position of the sampling point from 200 to 300 mm away from the head and tail of the titanium alloy ingot to the middle position of the titanium alloy ingot.

[0072] Sampling and testing: Take chip or block samples from the above five locations, the sampling depth is 3.0-5.0mm after peeling, and send the samples for component testing. The test results are shown in Table 2.

[0073] Table 2 Chemical composition of titanium alloys of Examples 1 to 4 and Comparative Examples 1 to 3 (percentage %)

[0074]

[0075] It should be noted that when sampling and testing the high-quality titanium alloys of Examples 1 to 4 and the titanium alloys of Comparative Examples 1 to 3, the contents of Fe, O, C, N, and H elements in the upper, middle, and lower parts were not tested, and the main elements were Al and V.

[0076] From Table 2 we can see that:

[0077] By comparing Example 1 and Comparative Example 1, it can be seen that the oxygen content of the titanium alloy ingot of Comparative Example 1 is higher than that of Example 1, and the oxygen content is increased by about 160 ppm compared with that of Example 1, and the oxygen increase is obvious. It can be seen that using a vacuum plasma welding box instead of manual welding can avoid the influence of external gas elements, thereby avoiding the phenomenon of weld oxidation and improving the yield rate of titanium alloy ingots.

[0078] By comparing Example 1 and Comparative Example 2, it can be seen that the contents of each element in Example 1 are not much different from those in Comparative Example 2, but the deviation range of the contents of each element in Example 1 is smaller than that in Comparative Example 2, that is, the deviation range of using a DC magnetic field is smaller than that of an AC magnetic field; thus, in terms of uniformity of chemical composition, using a DC magnetic field is better than using an AC magnetic field.

[0079] By comparing Example 1 and Comparative Example 3, it can be seen that the distribution of the easily segregated chemical elements of the titanium alloy ingot under the application of the magnetic field is relatively uniform compared to the distribution of the easily segregated chemical elements of the titanium alloy ingot under the application of the magnetic field.

[0080] It can be seen from Table 2 that, according to the smelting operability, the stability of the molten pool when the magnetic field is applied is greater than when the magnetic field is not applied, and the stabilizing effect of the DC magnetic field on the molten pool is greater than that of the AC magnetic field.

[0081] The high-quality titanium alloy of Example 1 and the titanium alloys of Comparative Examples 2 to 3 were subjected to 3 to 5 mm peeling treatment, and then the number of pores on one quarter of the surface of the ingot was counted. The results are shown in Table 3.

[0082] Table 3 Number of surface pores of titanium alloys in Example 1 and Comparative Examples 2-3

[0083] Arc stabilization method Number of pores on one quarter of the ingot surface Example 1 DC magnetic field 6～15 Comparative Example 2 AC magnetic field 12～20 Comparative Example 3 No magnetic field ≥25

[0084] Comparing Example 1 with Comparative Examples 2-3, it can be seen that the number of surface pores when a DC magnetic field is applied is smaller than that when an AC magnetic field is applied, and the number of surface pores when an AC magnetic field is applied is smaller than that when no magnetic field is applied.

[0085] It can be seen from Table 3 that according to the number of pores on the surface of the titanium alloy ingot after peeling, the effect of the magnetic field on the pores is DC magnetic field < AC magnetic field < no magnetic field.

[0086] In summary, the present invention provides a method for smelting and preparing high-quality titanium alloy. (1) The present invention adopts a mixing tank to stir and flip the mixing method, so that small particles of the material can be fully mixed with sponge titanium, thereby achieving full and uniform mixing of the material, ensuring the uniformity of the material to a great extent, avoiding the uneven distribution of various materials due to different particle sizes, and preliminarily improving the composition uniformity of the titanium alloy ingot; (2) The present invention adopts a vacuum plasma welding box instead of manual welding, and welds in a closed and argon-filled environment, thereby avoiding the influence of external gas elements and the occurrence of weld oxidation phenomenon, thereby improving the yield rate of titanium alloy ingots; (3) The present invention applies a DC stirring magnetic field (DC arc stabilizing current) in three vacuum consumable meltings, so that the molten pool is rotated and stirred in the same direction, so that the composition distribution of the titanium alloy ingot is more uniform; at the same time, low current, low voltage and short arc melting are adopted in the first vacuum consumable melting, which is conducive to a stable molten pool. The molten pool of short arc melting is shallow and cools faster, thereby avoiding Avoid element segregation and improve the impurity removal and purification effect of the molten pool; high current and high voltage are used in the second vacuum consumable melting, so that the components are further stirred evenly, and violent melting is conducive to effective impurity removal; low current and low voltage are used in the third vacuum consumable melting, which is conducive to the stability of the molten pool, further improving the uniformity of the composition of the titanium alloy ingot, and can further remove impurities and improve the purity of the titanium alloy ingot; the three vacuum consumable meltings work synergistically to improve the uniformity of the composition and the yield rate of the titanium alloy ingot; (4) The three vacuum consumable meltings of the present invention all include an arc-starting melting stage and a stable melting stage. The arc-starting melting stage gradually increases the current, heats the crucible and the consumable electrode before the molten droplet is generated, shortens the time from the establishment of the molten pool to the full establishment of the molten pool, and reduces the generation of cold shut at the bottom of the ingot; in the stable melting stage, the current is kept unchanged, the voltage is adjusted, and under the action of the DC stirring magnetic field, the arc is fully rotated to heat the edge of the molten pool, ensuring that the molten pool has good edge properties, and the molten pool is stable, reducing the generation of internal defects in the ingot. The present invention can be widely used in the field of titanium and titanium alloy material processing technology.

[0087] The embodiments described above are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, a person skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features may be replaced by equivalents. Such modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present application, and should all be included in the protection scope of the present application.

Claims

1. A method for smelting and preparing high-quality titanium alloy, characterized in that: The following steps are involved: (1) Weigh the raw materials of titanium alloy according to proportion and mix them evenly; (2) Pressing the uniformly mixed raw materials into consumable electrode blocks; (3) closely arranging and fixing the consumable electrode blocks, and welding them under vacuum conditions to obtain consumable electrodes; (4) Grinding, drying and dehumidifying the flash and welding points of the consumable electrode; (5) performing a first vacuum consumable melting on the consumable electrode after drying and dehumidification to obtain a primary ingot; (6) The primary ingot is cleaned and flattened, butt-welded and polished under vacuum conditions, and then the head and tail are turned around and a second vacuum consumable smelting is performed to obtain a secondary ingot; (7) The secondary ingot is flattened, and after the head and tail are turned over, a third vacuum consumable melting is performed to obtain a tertiary ingot, which is a high-quality titanium alloy.

2. The method for smelting and preparing high-quality titanium alloy according to claim 1, characterized in that: In step (1), the raw materials of the titanium alloy include sponge titanium and an intermediate alloy, and the weight percentage content of each element in the sponge titanium and the intermediate alloy is: Al: 3.60-4.10%, V: 21.0-22.0%, Fe≤0.09%, C≤0.025%, O≤0.10%, N≤0.010%, H≤0.010%, and the balance is Ti; wherein the particle size of the sponge titanium is 3.0-12.70 mm, and the Brinell hardness is ≤87.0 HB.

3. The method for smelting and preparing high-quality titanium alloy according to claim 1, characterized in that: In step (1), a mixing device is used to weigh the raw material of the titanium alloy, and a mixing tank is used to mix and stir the raw material of the titanium alloy for 1 to 2 minutes.

4. The method for smelting and preparing high-quality titanium alloy according to claim 1, characterized in that: In step (2), a hydraulic press is used to press the uniformly mixed raw materials into a consumable electrode block until the density of the consumable electrode block reaches 3.40 to 3.60 g / cm 3 .

5. The method for smelting and preparing high-quality titanium alloy according to claim 1, characterized in that: In step (3), the consumable electrode blocks are grouped into 10 to 15 blocks and welded in a vacuum plasma welding box. During welding, the vacuum is evacuated to ≤5.0Pa, the leakage rate is ≤2.0Pa / min, and argon is filled to a vacuum degree of 4×10 4 Pa, cooling after welding ≥1.0h, then out of the furnace.

6. The method for smelting and preparing high-quality titanium alloy according to claim 1, characterized in that: In step (4), the consumable electrode is polished to the original color of the metal at the welding position, and then placed in a drying furnace for drying and dehumidification treatment at 100-150° C. for not less than 12 hours.

7. The method for smelting and preparing high-quality titanium alloy according to claim 1, characterized in that: In step (5), the consumable electrode after drying and dehumidification is placed in a vacuum consumable furnace for vacuum consumable melting within 30 minutes. The parameters of the first vacuum consumable melting are: vacuum degree ≤3.0Pa; leakage rate ≤0.80Pa / min; melting current 2-15kA; arc stabilization current adopts DC 2.0-8.0A; melting rate is 4.0-15.0kg / min; cooling water temperature is maintained at 40°C or below; argon filling cooling time after melting is ≥4.0h.

8. The method for smelting and preparing high-quality titanium alloy according to claim 1, characterized in that: In step (6), a vacuum plasma welding box is used for head-to-tail welding. During welding, the vacuum is evacuated to ≤5.0Pa, the leakage rate is ≤2.0Pa / min, and argon is filled to a vacuum degree of 4×10 4 Pa, cooling after welding ≥1.0h, then out of the furnace.

9. The method for smelting and preparing high-quality titanium alloy according to claim 1, characterized in that: In step (6), during the second vacuum consumable melting, the head of the primary ingot faces downward and the tail faces upward; the parameters of the second vacuum consumable melting are: vacuum degree ≤2.0Pa; leakage rate ≤0.80Pa / min; melting current 5-25kA; arc stabilization current adopts DC 2.0-10.0A; melting rate is 5.0-18.0kg / min; cooling water temperature is maintained at 45°C or below; argon filling cooling time after melting is ≥6.0h.

10. The method for smelting and preparing high-quality titanium alloy according to claim 1, characterized in that: In step (7), the parameters of the third vacuum consumable melting are: vacuum degree ≤1.0Pa; leakage rate ≤0.80Pa / min; melting current 8-24kA; arc stabilization current adopts DC 2.0-10.0A; melting rate is 5.0-18.0kg / min; cooling water temperature is maintained at 45°C or below; at the end of melting, when the weight of the consumable electrode is reserved at 200kg, the feeding stage is entered, and the feeding current is 0-10kA; and the argon filling cooling time after melting is ≥7.0h.

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