Arc starting melting method and melting method of titanium ingot, titanium ingot and titanium product

Abstract

The present application relates to an arc starting melting method and a melting method for titanium ingots, titanium ingots and titanium products. The arc starting melting method for titanium ingots includes the following steps: preheating a titanium alloy consumable electrode with a first current under an inert atmosphere of 8000 Pa to 80000 Pa; melting the preheated titanium alloy consumable electrode with a second current under vacuum conditions; wherein the first current is less than the second current. Using the inert gas under the inert atmosphere as a heat conduction medium can effectively avoid situations such as cold shut and porosity at the bottom of the ingot, thereby effectively improving the quality of the bottom of the titanium ingot.

Description

Technical Field

[0001] This application relates to the field of metals, and particularly to an arc starting melting method and melting method of titanium ingots, titanium ingots and titanium products. Background Art

[0002] Vacuum consumable arc melting (VAR) is the main melting method for preparing high-quality titanium and titanium alloy ingots, including an arc starting stage, a normal melting stage and a feeding stage. In traditional vacuum consumable arc melting, a water-cooled copper crucible is usually used as a condenser and it is carried out in an environment with a relatively high vacuum degree (≤30 Pa). However, cold shuts, porosity and other conditions are likely to occur at the bottom of the titanium alloy ingots produced by the traditional vacuum consumable arc melting method; if not removed by turning, during the subsequent forging process, these cold shuts and porosity will cause stress concentration and become crack sources, leading to cracking at the ends of the bars.

[0003] Therefore, it is of great significance to provide a melting method for titanium ingots that can effectively avoid cold shuts and porosity. Summary of the Invention

[0004] Based on this, this application provides an arc starting melting method and melting method of titanium ingots, titanium ingots and titanium products that can effectively avoid cold shuts and porosity.

[0005] The technical solutions for this application to solve the above technical problems are as follows.

[0006] An arc starting melting method of a titanium ingot, comprising the following steps:

[0007] Under an inert atmosphere of 8000 Pa to 80000 Pa, preheat the titanium alloy consumable electrode with a first current;

[0008] Under vacuum conditions, melt the preheated titanium alloy consumable electrode with a second current; the first current is less than the second current.

[0009] In some embodiments, in the arc starting melting method of the titanium ingot, the first current is 3 KA to 7 KA, and the second current is 10 KA to 35 KA.

[0010] In some embodiments, in the arc starting melting method of the titanium ingot, the inert gas in the inert atmosphere is selected from at least one of argon and helium.

[0011] In some embodiments, in the arc starting melting method of the titanium ingot, the preheating step is carried out at a first voltage, the first voltage is 12 V to 18 V, and the preheating time is 8 min to 20 min.

[0012] In some of these embodiments, in the arc starting melting method of the titanium ingot, the melting step is carried out at a second voltage, and the second voltage is 20V to 35V.

[0013] In some of these embodiments, in the arc starting melting method of the titanium ingot, the pressure of the vacuum condition is ≤ 30 Pa.

[0014] In some of these embodiments, in the arc starting melting method of the titanium ingot, after the preheating step and before the melting step, it further includes the step of raising the first current to the second current within 2 min to 5 min under the inert atmosphere.

[0015] In some of these embodiments, in the arc starting melting method of the titanium ingot, after the preheating step and before the melting step, it further includes the step of raising the first voltage to the second voltage within 2 min to 5 min under the inert atmosphere.

[0016] This application provides a melting method for a titanium ingot, including an arc starting stage, a normal melting stage, and a feeding stage, and the arc starting stage adopts the above-mentioned arc starting melting method for the titanium ingot.

[0017] In some of these embodiments, in the normal melting stage of the melting method of the titanium ingot, the melting current is 10KA to 35KA, and the melting voltage is 20V to 35V.

[0018] In some of these embodiments, in the melting method of the titanium ingot, the atmosphere pressure in the normal melting stage and the feeding stage is ≤ 30 Pa.

[0019] This application provides a titanium ingot prepared by the above-mentioned melting method of the titanium ingot.

[0020] This application provides a titanium product processed from the above-mentioned titanium ingot.

[0021] Compared with the prior art, the arc starting melting method of the titanium ingot in this application has the following beneficial effects:

[0022] In the above-mentioned arc starting melting method of the titanium ingot, under an inert atmosphere with a specific pressure, after preheating the titanium alloy consumable electrode with a lower first current, it is then melted under a vacuum condition with a higher second current; among them, the inert gas under the inert atmosphere is used as a heat conduction medium to effectively improve the uniform heat transfer ability of the heat accumulated at the bottom of the electrode to be melted to the bottom pad, coordinate the solidification shrinkage characteristics when the melt contacts the bottom pad, and reduce the temperature difference when the melt solidifies on the bottom pad, thereby effectively avoiding situations such as cold shut and porosity at the bottom of the ingot, and further effectively improving the quality of the bottom of the titanium ingot; ultimately, it is realized that the bottom of the titanium ingot can be directly transferred to forging without machining, effectively improving the yield rate of the titanium ingot, reducing the labor intensity, and enhancing the economic value. Description of the Drawings

[0023] To more clearly illustrate the specific embodiments of the present application or the technical solutions in the prior art, the following will briefly introduce the drawings required for the description of the specific embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present application. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0024] Figure 1 Bottom quality diagram of the titanium finished ingot obtained in Example 1;

[0025] Figure 2 Bottom quality diagram of the titanium finished ingot obtained in Comparative Example 1. Specific embodiments

[0026] The following further elaborates on the technical solutions of the present application in combination with specific embodiments. The present application can be implemented in many different forms and is not limited to the embodiments described herein. It should be understood that the purpose of providing these embodiments is to make the understanding of the disclosed content of the present application more thorough and comprehensive.

[0027] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the technical field to which this application belongs. The terms used in the description of this application are only for the purpose of describing specific embodiments and are not intended to limit this application. The term "and / or" used herein includes any and all combinations of one or more of the related listed items.

[0028] In the description of this application, it should be understood that the terms "first" and "second" are only used for descriptive purposes and cannot be construed as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include one or more of such features. In the description of this application, "a plurality" means two or more, unless otherwise specifically defined.

[0029] The weights of the relevant components mentioned in the description of the embodiments of this application not only can refer to the specific contents of each component, but also can represent the proportional relationship of the weights between the components. Therefore, as long as the contents of the relevant components in the description of the embodiments of this application are scaled up or down in proportion, they are within the scope disclosed in the description of the embodiments of this application. Specifically, the weights described in the description of the embodiments of this application can be mass units well-known in the chemical industry such as μg, mg, g, kg, etc.

[0030] The consumable electrode melting furnace, also known as vacuum consumable electrode arc melting (VAR), is a process where the consumable electrode produced by an induction melting furnace is heated and melted through a controllable alternating current arc in a vacuum environment.

[0031] After analysis by the technical personnel of this application, the reasons for the easy occurrence of cold shuts, porosity, etc. at the bottom of titanium ingots produced by the traditional vacuum consumable arc melting method include: In the arc starting stage of melting, due to the good heat conduction effect of the water-cooled copper crucible, under the action of strong cooling water outside the crucible, after the melted droplets fall on the bottom pad of the water-cooled copper crucible, they will solidify immediately. At this time, cold shuts, porosity, etc. are likely to occur at the bottom of the titanium ingot. Even in the initial stage of arc starting, when preheating with a small current in a high vacuum environment, at this time the arc travels on the bottom pad of the crucible and no melting occurs. However, due to the relatively fast heat conduction of the bottom pad, the temperature at the bottom of the consumable electrode to be melted is much higher than the temperature of the bottom pad of the crucible. That is, when starting the arc and melting in a high vacuum environment, the heat at the bottom of the consumable electrode to be melted cannot be effectively transferred to the bottom pad, and cold shuts, porosity, etc. at the bottom of the titanium ingot still cannot be avoided.

[0032] An arc starting and melting method for titanium ingots is provided in an embodiment of this application, including steps S10 to S20:

[0033] Step S10: Preheat the titanium alloy consumable electrode with a first current in an inert atmosphere of 8000 Pa to 80000 Pa.

[0034] This application proposes to use the inert gas in the inert atmosphere as a heat conduction medium to effectively improve the uniform heat transfer ability of the heat accumulated at the bottom of the consumable electrode to be melted to the bottom pad, coordinate the solidification shrinkage characteristics when the melt contacts the bottom pad, reduce the temperature difference when the melt solidifies on the bottom pad, thereby effectively avoiding cold shuts and porosity at the bottom of the ingot, and further effectively improving the quality of the bottom of the titanium ingot; ultimately achieving that the bottom of the titanium ingot can be directly transferred to forging without machining, effectively improving the yield of the titanium ingot, reducing the labor intensity, and having great economic value.

[0035] It can be understood that the titanium ingot is the abbreviation of titanium and titanium alloy ingots; further, the titanium ingot includes but is not limited to TA1 (nominal composition Ti, i.e., pure titanium), TA4 (nominal composition Ti - 0.3Fe), TC4 (nominal composition Ti - 6Al - 4V) titanium alloy ingots, TC11 (nominal composition Ti - 6.5Al - 3.5Mo - 1.5Zr - 0.3Si) titanium alloy ingots, TA15 (nominal composition Ti - 7.5Al - 1Mo - 1V - 2Zr) titanium alloy ingots, TC18 (nominal composition Ti - 5Al - 5Mo - 5V - 1Cr - 1Fe) titanium alloy ingots.

[0036] It can be further understood that the pressure under an inert atmosphere includes, but is not limited to, 8000 Pa, 9000 Pa, 10000 Pa, 15000 Pa, 20000 Pa, 30000 Pa, 10000 Pa, 50000 Pa, 60000 Pa, 70000 Pa, 80000 Pa.

[0037] Optionally, under an inert atmosphere of 20000 Pa to 80000 Pa, the consumable electrode of the titanium alloy is preheated with a first current.

[0038] In some of these examples, in step S10, the pressure is set to 8000 Pa to 80000 Pa, the inert gas valve is opened, and argon or helium of 8000 Pa to 80000 Pa is filled into the vacuum furnace chamber.

[0039] In some of these examples, in step S10, the first current is 3 KA to 7 KA.

[0040] It can be understood that the magnitude of the first current includes, but is not limited to, 3 KA, 4 KA, 4.5 KA, 5 KA, 5.5 KA, 6 KA, 6.5 KA, 7 KA.

[0041] In some of these examples, in step S10, the inert gas in the inert atmosphere is selected from at least one of argon and helium.

[0042] Optionally, the inert gas in the inert atmosphere is argon.

[0043] In some of these examples, in step S10, the preheating step is carried out at a first voltage, and the first voltage is 12 V to 18 V.

[0044] It can be understood that the magnitude of the first voltage includes, but is not limited to, 12 V, 13 V, 14 V, 15 V, 16 V, 17 V, 18 V.

[0045] In some of these examples, in step S10, the preheating time is 8 min to 20 min.

[0046] It can be understood that the preheating time includes, but is not limited to, 8 min, 10 min, 12 min, 14 min, 15 min, 16 min, 17 min, 18 min, 19 min, 20 min.

[0047] Optionally, the preheating time is 10 min to 15 min.

[0048] In some of these examples, after the preheating step in step S10 and before performing step S20, it further includes a step of increasing the first current to a second current within 2 min to 5 min under an inert atmosphere.

[0049] In some of these examples, after the preheating step of step S10 and before performing step S20, it further includes a step of raising the first voltage to the second voltage within 2 min to 5 min under an inert atmosphere.

[0050] It can be understood that under an inert atmosphere of 8000 Pa to 80000 Pa, the melting current is raised to 10 KA to 35 KA within 2 min to 5 min, and the melting voltage is raised to 20 V to 35 V within 2 min to 5 min.

[0051] Optionally, the current and voltage are raised under an inert atmosphere of 20000 Pa to 80000 Pa.

[0052] Optionally, the melting current is raised to 10 KA to 35 KA within 3 min to 5 min, and the melting voltage is raised to 20 V to 35 V within 3 min to 5 min.

[0053] In some of these examples, after the steps of raising the first current to the second current and raising the first voltage to the second voltage, and before performing step S20, it further includes a step of pumping to a vacuum.

[0054] Furthermore, the pumping step includes: closing the inert gas valve, setting the furnace chamber vacuum to below 30 Pa, and under the evacuation of the vacuum system, the pressure of the inert gas is finally reduced to below 30 Pa.

[0055] Optionally, the pumping time is 3 min to 15 min.

[0056] It can be understood that the pumping time includes but is not limited to 3 min, 5 min, 8 min, 10 min, 12 min, 15 min.

[0057] In some of these examples, in step S10, the titanium alloy consumable electrode is solid.

[0058] In some of these examples, in step S10, the diameter specification of the titanium alloy consumable electrode is Φ340 mm to Φ980 mm.

[0059] It can be understood that the diameter specification of the titanium alloy consumable electrode includes but is not limited to Φ340 mm, Φ420 mm, Φ500 mm, Φ620 mm, Φ720 mm, Φ850 mm, Φ980 mm.

[0060] In some of these examples, in step S10, the mass of the titanium alloy consumable electrode is 2000 Kg to 15000 Kg.

[0061] It can be understood that the mass of the titanium alloy consumable electrode includes but is not limited to 2000 Kg, 3000 Kg, 5000 Kg, 8000 Kg, 10000 Kg, 12000 Kg, 15000 Kg.

[0062] In some of these examples, in step S10, the crucible diameter used is Φ500 mm to Φ1080 mm.

[0063] It can be understood that the crucible diameter includes but is not limited to Φ420 mm, Φ500 mm, Φ580 mm, Φ680 mm, Φ780 mm, Φ880 mm, Φ980 mm, Φ1080 mm.

[0064] In some of these examples, in step S10, the preparation of the titanium alloy consumable electrode includes the following steps:

[0065] After making the raw materials required for preparing the titanium or titanium alloy ingot into electrode blocks, the electrode blocks are then welded into a welded electrode.

[0066] In some of these examples, in the preparation steps of the titanium alloy consumable electrode, the mass of a single electrode block is 40 Kg to 120 Kg.

[0067] It can be understood that by using the above arc starting melting method for the titanium ingot during the last melting, situations such as cold shuts and porosity at the bottom of the ingot can be avoided. Further, it can be understood that the above arc starting melting method for the titanium ingot is not limited to being used during the last melting.

[0068] In some of these examples, in the preparation steps of the titanium alloy consumable electrode, the welded electrode is used as a consumable electrode for at least 1 time of vacuum consumable arc melting to obtain the titanium alloy consumable electrode.

[0069] It can be understood that as the number of melting times of the titanium alloy consumable electrode increases, the diameter of the crucible increases step by step; for example, when the titanium alloy consumable electrode is prepared using a Φ420 crucible, the last melting uses a Φ500 crucible; when the titanium alloy consumable electrode is prepared using a Φ580 crucible, the last melting uses a Φ680 crucible; when the titanium alloy consumable electrode is prepared using a Φ780 crucible, the last melting uses a Φ880 crucible.

[0070] In some of these examples, in step S10, when the last melting uses a Φ680 crucible, the first current is 3 KA to 4 KA, and the first voltage is 12 V to 14 V.

[0071] In some of these examples, in step S10, when the last melting uses a Φ880 crucible, the first current is 4 KA to 5 KA, and the first voltage is 14 V to 16 V.

[0072] In some of these examples, in step S10, when the last melting uses a Φ1080 crucible, the first current is 6KA to 7KA, and the first voltage is 16V to 18V.

[0073] Step S20: Under vacuum conditions, melt the preheated titanium alloy consumable electrode with a second current; wherein, the first current is less than the second current.

[0074] At the end of arc starting, when the molten pool is already sound and the bottom of the ingot has been formed, the argon or helium gas is then pumped out, and the system returns to a high vacuum state, so that the system does not need to continue to fill argon or helium gas to maintain the dynamic balance of the low vacuum, avoiding the consumption of argon or helium gas.

[0075] It can be understood that the arc starting melting method of the titanium ingot provided by the present application includes an inflation preparation stage, a small current preheating stage, a current increasing stage, and a gas pumping stage.

[0076] In some of these examples, in step S20, the second current is 10KA to 35KA.

[0077] It can be understood that the magnitude of the second current includes but is not limited to 10KA, 12KA, 14KA, 15KA, 18KA, 20KA, 22KA, 25KA, 28KA, 30KA, 32KA, 35KA.

[0078] In some of these examples, in step S20, the melting step is carried out at a second voltage, and the second voltage is 20V to 35V.

[0079] It can be understood that the magnitude of the second voltage includes but is not limited to 20V, 22V, 25V, 28V, 30V, 32V, 34V, 35V.

[0080] In some of these examples, in step S20, when the last melting uses a Φ680 crucible, the second current is 12KA to 25KA, and the second voltage is 22V to 30V.

[0081] In some of these examples, in step S20, when the last melting uses a Φ880 crucible, the second current is 18KA to 30KA, and the second voltage is 26V to 33V.

[0082] In some of these examples, in step S20, when the last melting uses a Φ1080 crucible, the second current is 25KA to 35KA, and the second voltage is 29V to 35V.

[0083] In some of these examples, in step S20, the pressure of the vacuum condition ≤ 30Pa.

[0084] An embodiment of the present application provides a method for melting titanium ingots, including an arc starting stage, a normal melting stage, and a feeding stage. The arc starting stage adopts the arc starting melting method of the above titanium ingots.

[0085] It can be understood that when melting, adopting the arc starting melting method of the above titanium ingots can avoid situations such as cold shuts and porosity at the bottom of the ingot.

[0086] In some examples, during the normal melting stage of the titanium ingot melting method, the melting current is 10 KA to 35 KA, and the melting voltage is 20 V to 35 V.

[0087] It can be understood that the melting current and melting voltage in the normal melting stage are respectively consistent with the melting current and melting voltage in the arc starting stage.

[0088] In some examples, the atmosphere pressure in the normal melting stage and the feeding stage of the titanium ingot melting method is ≤ 30 Pa.

[0089] An embodiment of the present application provides a titanium ingot prepared by the above titanium ingot melting method.

[0090] An embodiment of the present application provides the application of the above titanium ingot in the preparation of titanium products. Another embodiment of the present application provides a titanium product processed from the above titanium ingot.

[0091] The above titanium ingot is used to prepare titanium products, which can endow the titanium products with high quality and high yield.

[0092] In some embodiments, the titanium products include but are not limited to aircraft engine compressor components, structural components of rockets and missiles, etc.

[0093] In some embodiments, the material of the titanium product can be the above titanium ingot, that is, the above titanium ingot is directly used to prepare the titanium product. In other embodiments, the material of the titanium product can include other materials in addition to the above titanium ingot. Specific Embodiments

[0095] The following examples are given according to the arc starting melting method and melting method of the titanium ingot of the present application, the titanium ingot and the titanium product. It can be understood that the arc starting melting method and melting method of the titanium ingot of the present application, the titanium ingot and the titanium product are not limited to the following embodiments.

[0096] Example 1

[0097] Preparation of a TC18 (nominal composition Ti-5Al-5Mo-5V-1Cr-1Fe) titanium alloy ingot with a target specification of Φ680 mm:

[0098] (1) Stack and weld TC18 electrode blocks with a single weight of 46 Kg and a diameter of Φ420 mm to prepare a 4048 Kg welded electrode. The welded electrode is subjected to vacuum consumable arc melting twice to obtain a Φ580 mm TC18 titanium alloy ingot;

[0099] (2) Using the Φ580 mm TC18 titanium alloy ingot as the consumable electrode and a crucible with a specification of Φ680 mm, perform the final melting in a vacuum consumable arc furnace: evacuate the system to below 10 Pa, set the pressure in the furnace chamber to 50000 Pa, open the argon filling valve, and fill the vacuum furnace chamber with argon at 50000 Pa. Start the arc with a current and voltage of 4 KA / 13 V. After preheating for 12 min, increase the current and voltage to 20 KA / 25 V in 3 min. After reaching the target current and voltage, close the argon filling valve, set the pressure in the furnace chamber to 4 Pa, and the vacuum system automatically evacuates the atmosphere pressure to 4 Pa within 12 min. Maintain the current and voltage and enter the normal melting stage. After the feeding stage and tripping, wait for the ingot to cool and be taken out of the furnace to obtain the finished ingot. The bottom quality diagram is as Figure 1 shown.

[0100] From Figure 1 it can be seen that the bottom quality of the finished ingot obtained in Example 1 is good, without cold lap or porosity, and it is determined that the bottom does not need to be turned off; at least one layer of 5 mm turning work that needs to be performed by the lathe feed is eliminated, saving about 7 Kg of titanium alloy material, saving about 0.5 loss of YG8 cemented carbide tools, and saving about 4 h of machining time.

[0101] Example 2

[0102] Preparation of a TC18 (nominal composition Ti-5Al-5Mo-5V-1Cr-1Fe) titanium alloy ingot with a target specification of Φ680 mm:

[0103] (1) Stack and weld TC18 electrode blocks with a single weight of 46 Kg and a diameter of Φ420 mm to prepare a 4048 Kg welded electrode. The welded electrode is subjected to vacuum consumable arc melting twice to obtain a Φ580 mm TC18 titanium alloy ingot;

[0104] (2) Using a Φ580mm TC18 titanium alloy ingot as the consumable electrode, a crucible with a specification of Φ680mm was used for the final melting in a vacuum consumable arc furnace: the system was evacuated to below 10 Pa, the pressure in the furnace chamber was set to 20000 Pa, the argon filling valve was opened, and argon gas at 20000 Pa was filled into the vacuum furnace chamber. An arc was struck with a current voltage of 4KA / 13V. After preheating for 12 minutes, the current and voltage were increased to 20KA / 25V respectively in 3 minutes. After reaching the target current voltage, the argon filling valve was closed, the pressure in the furnace chamber was set to 2 Pa, and the vacuum system automatically evacuated the atmosphere pressure to 2 Pa within 14 minutes. Keeping the current and voltage, it entered the normal melting stage. After the feeding stage and tripping, after the ingot cooled and was taken out of the furnace, a finished ingot was obtained.

[0105] Upon observation, the bottom quality of the finished ingot obtained in Example 2 was good, without cold shuts or porosity, and it was determined that the bottom did not need to be turned off.

[0106] Example 3

[0107] Preparation of a TC4 (nominal composition Ti-6Al-4V) titanium alloy ingot with a target specification of Φ880mm:

[0108] (1) Stacked and welded TC4 electrode blocks with a single weight of 64 Kg and a diameter of Φ580mm to prepare a 7462 Kg welded electrode. The welded electrode was melted twice by vacuum consumable arc melting to obtain a Φ780mm TC4 titanium alloy ingot.

[0109] (2) Using a Φ780mm TC4 titanium alloy ingot as the consumable electrode, a crucible with a specification of Φ880mm was used for the final melting in a vacuum consumable arc furnace: the system was evacuated to below 20 Pa, the pressure in the furnace chamber was set to 60000 Pa, the argon filling valve was opened, and argon gas at 60000 Pa was filled into the vacuum furnace chamber. An arc was struck with a current voltage of 5KA / 15V. After preheating for 12 minutes, the current and voltage were increased to 25KA / 30V respectively in 3 minutes. After reaching the target current voltage, the argon filling valve was closed, the pressure in the furnace chamber was set to 8 Pa, and the vacuum system automatically evacuated the atmosphere pressure to 8 Pa within 11 minutes. Keeping the current and voltage, it entered the normal melting stage. After the feeding stage and tripping, after the ingot cooled and was taken out of the furnace, a finished ingot was obtained.

[0110] Upon observation, the bottom quality of the obtained finished ingot was good, without cold shuts or porosity, and it was determined that the bottom did not need to be turned off; it eliminated at least one layer of 5mm turning work that the lathe feed required, saved about 13 Kg of titanium alloy material, saved about 0.7 loss of YG8 hard alloy tools, and saved about 6 hours of machining time.

[0111] Example 4

[0112] Preparation of TA1 (nominal composition pure Ti) titanium alloy ingot with a target specification of Φ1080mm:

[0113] (1) Stack and weld TA1 electrode blocks with a single weight of 91 Kg and a diameter of Φ880mm to prepare a 11200 Kg welded electrode. The welded electrode is subjected to vacuum consumable arc melting once to obtain a Φ980mm TA1 titanium ingot;

[0114] (2) Using the Φ980mm TA1 titanium ingot as the consumable electrode and a crucible with a specification of Φ1080mm, perform the final melting in a vacuum consumable arc furnace: evacuate the system vacuum to below 20 Pa, set the pressure in the furnace chamber to 80000 Pa, open the argon filling valve, and fill the vacuum furnace chamber with argon at 80000 Pa. Start the arc with a current voltage of 6KA / 27V. After maintaining for 14 min, increase the current voltage to 30KA / 32V in 4 min. After reaching the target current voltage, close the helium filling valve, set the pressure in the furnace chamber to 12 Pa, and the vacuum system automatically evacuates the atmosphere pressure to 12 Pa within 10 min. Maintain the current voltage and enter the normal melting stage. After the feeding stage and tripping, after the ingot cools and is taken out of the furnace, the finished ingot is obtained.

[0115] Upon observation, the bottom of the obtained finished ingot has good quality, without cold shut and porosity. It is determined that the bottom does not need to be turned. This eliminates at least one layer of 5mm turning work on the lathe, saving about 20 Kg of titanium material, about 0.9 loss of YG8 hard alloy tools, and about 8 h of machining time.

[0116] Comparative Example 1

[0117] It is basically the same as Example 1, except that in the arc starting stage, there is no argon filling and argon evacuation link. That is, in step (2), directly under a vacuum degree of about 4 Pa, start the arc with a current voltage of 4KA / 13V. After preheating for 12 min, increase the current voltage to 20KA / 25V in 3 min. Maintain the current voltage and enter the normal melting stage. After the feeding stage and tripping, after the ingot cools and is taken out of the furnace, the finished ingot is obtained. The bottom quality diagram is as Figure 2 shown.

[0118] Upon observation, the bottom of the obtained finished ingot has poor quality, with obvious cold shut and porosity. The bottom needs to be turned off about 5mm, consuming about 7 Kg of titanium alloy material, about 0.5 loss of YG8 hard alloy tools, and about 4 h of machining time.

[0119] Comparative Example 2

[0120] It is basically the same as Example 2, except that there is no argon filling and argon pumping in the arc starting stage. That is, in step (2), directly under a vacuum degree of about 2 Pa, an arc is started with a current voltage of 4 kA / 13 V. After preheating for 12 min, the current and voltage are increased to 20 kA / 25 V respectively in 3 min, and the current and voltage are maintained to enter the normal melting stage. After the feeding stage and tripping, after the ingot cools and is taken out of the furnace, a finished ingot is obtained.

[0121] Upon observation, the bottom quality of the obtained finished ingot is poor, with obvious cold shuts and porosity. Approximately 5 mm needs to be machined off the bottom, consuming about 7 kg of titanium alloy material, about 0.5 YG8 hard alloy cutting tools are consumed, and about 4 h of machining time is consumed.

[0122] Comparative Example 3

[0123] It is basically the same as Example 3, except that there is no argon filling and argon pumping in the arc starting stage. That is, in step (2), directly under a vacuum degree of about 8 Pa, an arc is started with a current voltage of 5 kA / 15 V. After preheating for 12 min, the current and voltage are increased to 25 kA / 30 V respectively in 3 min, and the current and voltage are maintained to enter the normal melting stage. After the feeding stage and tripping, after the ingot cools and is taken out of the furnace, a finished ingot is obtained.

[0124] Upon observation, the bottom quality of the obtained finished ingot is poor, with obvious cold shuts and porosity. Approximately 5 mm needs to be machined off the bottom, consuming about 13 kg of titanium alloy material, about 0.7 YG8 hard alloy cutting tools are consumed, and about 6 h of machining time is consumed.

[0125] Comparative Example 4

[0126] It is basically the same as Example 4, except that there is no argon filling and argon pumping in the arc starting stage. That is, in step (2), directly under a vacuum degree of about 12 Pa, an arc is started with a current voltage of 6 kA / 27 V. After preheating for 14 min, the current and voltage are increased to 30 kA / 32 V respectively in 4 min, and the current and voltage are maintained to enter the normal melting stage. After the feeding stage and tripping, after the ingot cools and is taken out of the furnace, a finished ingot is obtained.

[0127] Upon observation, the bottom quality of the obtained finished ingot is poor, with obvious cold shuts and porosity. Approximately 5 mm needs to be machined off the bottom, consuming about 20 kg of titanium material, about 0.9 YG8 hard alloy cutting tools are consumed, and about 8 h of machining time is consumed.

[0128] Comparative Example 5

[0129] It is basically the same as Example 1, except that in step (2), the pressure in the furnace chamber is set to 800 Pa, and the argon filling valve is opened to fill the vacuum furnace chamber with argon at 800 Pa.

[0130] Upon observation, there are a small number of cold shuts and porosity in the quality of the bottom of the obtained finished ingot. Approximately 5 mm needs to be turned off from the bottom, consuming about 7 kg of titanium alloy material, about 0.5 loss of YG8 cemented carbide cutting tools, and about 4 hours of machining time.

[0131] The technical features of the above-described embodiments can be combined arbitrarily. For the sake of brevity of description, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, it should be considered as within the scope described in this specification.

[0132] The above-described embodiments only represent several implementation manners of the present application, which are convenient for understanding the technical solutions of the present application specifically and in detail, but should not be construed as a limitation on the protection scope of the invention patent. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present application, several deformations and improvements can still be made, and these all belong to the protection scope of the present application. It should be understood that the technical solutions obtained by those skilled in the art through logical analysis, reasoning or limited experiments on the basis of the technical solutions provided in the present application are all within the protection scope of the appended claims of the present application. Therefore, the protection scope of the patent of the present application shall be subject to the content of the appended claims, and the description and drawings can be used to explain the content of the claims.

Claims

1. A method for starting arc melting of a titanium ingot, characterized in that, It includes the following steps: Under an inert atmosphere of 8000 Pa to 80000 Pa, preheat the titanium alloy consumable electrode with a first current; Under vacuum conditions, melt the preheated titanium alloy consumable electrode with a second current; the first current is less than the second current; The first current is 3 KA to 6 KA, and the second current is 10 KA to 35 KA; The preheating step is carried out at a first voltage, the first voltage is 12 V to 18 V, and the preheating time is 8 min to 14 min; The pressure of the vacuum conditions is ≤ 30 Pa.

2. The arc starting melting method of the titanium ingot according to claim 1, characterized in that, The melting step is carried out at a second voltage, the second voltage is 20 V to 35 V.

3. The arc starting melting method of the titanium ingot according to claim 1, characterized in that, The inert gas in the inert atmosphere is selected from at least one of argon and helium.

4. The arc starting melting method of the titanium ingot according to claim 1, characterized in that, After the preheating step and before the melting step, it further includes the step of raising the first current to the second current within 2 min to 5 min under the inert atmosphere.

5. A method for smelting titanium ingots, characterized in that, It includes an arc starting stage, a normal melting stage, and a feeding stage, and the arc starting stage adopts the arc starting melting method of the titanium ingot as described in any one of claims 1 to 4.

6. The melting method of the titanium ingot according to claim 5, characterized in that, The melting method includes at least one of the following (1) to (2) features: (1) In the normal melting stage, the melting current is 10 KA to 35 KA, and the melting voltage is 20 V to 35 V; (2) The atmosphere pressure in the normal melting stage and the feeding stage is ≤ 30 Pa.

7. A titanium ingot, characterized in that, It is prepared by the melting method of the titanium ingot as described in any one of claims 5 to 6.

8. A titanium product, characterized in that, It is processed from the titanium ingot as described in claim 7.

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