Intermittent arcing method, cast ingot and application

Abstract

The invention discloses a discontinuous arcing method, a cast ingot and application, belongs to the technical field of titanium alloy, and solves the problems that in the prior art, an arc striking material in an arcing process cannot be completely melted, so that the bottom of the cast ingot is half-cooked or segregated, other impurities are introduced, and the purity and cleanliness of the arc striking material directly influence the impurity content in the smelting process; and the problem that the bottom of the crucible is damaged due to direct arcing without an arc striking material is also solved. According to the method disclosed by the invention, the bottom of the crucible is intermittently preheated under the conditions of low current and low voltage, namely arcing, keeping, power failure, arcing, keeping, power failure, arcing, keeping and normal arcing smelting, the arcing process does not need to utilize an arc striking material, and the quality problem of half-green or segregation of the arc striking material to the bottom of the cast ingot can be eliminated; and the phenomenon that the bottom of the crucible is damaged by instant electric arc due to direct smelting and arc starting under the arc starting current and voltage of normal work can be prevented, and the production safety is improved.

Description

Technical Field

[0001] This invention relates to the field of titanium and titanium alloy ingot smelting technology, and particularly to a method for intermittent arc initiation, ingot casting, and its application. Background Technology

[0002] With the rapid development of high-tech fields such as aerospace and national defense, the performance and quality requirements for titanium alloy materials are increasing. Titanium alloys are widely used in these fields due to their excellent specific strength, corrosion resistance, and high-temperature performance. The smelting process of titanium alloys is complex, and the control of defects such as compositional homogeneity, inclusions, and segregation is extremely demanding. Therefore, developing efficient and high-quality titanium alloy smelting technologies is particularly important.

[0003] Arc ignition is the first stage of VAR (vacuum arc melting). Its main purpose is to ignite the arc between the consumable electrode and the crystallizer base and quickly transition to a stable combustion stage, while simultaneously establishing a molten pool of a certain depth to create conditions for transitioning to the normal melting period. In actual production, the arc ignition method is as follows: under low voltage (less than 60V), the two electrodes are first short-circuited and then pulled apart. Instantly, the current density between the two electrodes is extremely high, generating high temperature, and the cathode emits electrons to produce an arc. During arc ignition, under the action of strong current, the crystallizer base is prone to burnout, contaminating the molten metal, and may also cause crystallizer breakage, leading to safety accidents. This is even more serious when the arc is unstable. Current VAR (Vacuum-Anaerobic Reduction) arc-starting techniques for titanium alloy smelting use sponge titanium or titanium alloy shavings of the same grade as the arc-starting material. The advantage is that it prevents damage to the crucible bottom from the instantaneous arc during smelting; minor damage may cause copper from the crucible bottom to melt into the titanium alloy ingot, while severe damage could puncture the crucible bottom and cause a safety accident. The disadvantages are that the arc-starting material cannot be completely melted, resulting in inclusions or segregation at the bottom of the ingot; it may also introduce other impurities. The purity and cleanliness of the arc-starting material directly affect impurity control during the smelting process. If the sponge titanium contains a large amount of Fe, C, or other impurities, these impurities may enter the titanium alloy, affecting the compositional uniformity and metallurgical quality. Another arc-starting technique uses a bottom pad to reduce the cooling intensity at the bottom of the ingot, preventing molten electrode dripping onto the bottom pad and causing rapid cooling, which could lead to inclusions of high-melting-point metals and damage to the crucible base.

[0004] In existing technologies, the arc-initiating process, using an arc-initiating material, involves slowly lowering the consumable electrode and igniting an electric arc between the electrode and the crystallizer base. The feed switch of the electric arc furnace is then immediately shut off to stop the electrode's descent and maintain arc stability. Once a molten pool forms on the crystallizer base, the feed switch is reopened for normal melting. However, this method cannot completely melt the arc-initiating material, which can lead to undercooked or segregated ingots and potentially introduce other impurities. The purity and cleanliness of the arc-initiating material directly affect impurity control during the melting process, impacting the compositional uniformity and metallurgical quality of the titanium alloy ingot. Summary of the Invention

[0005] In view of the above, the present invention aims to provide a method, ingot and application of intermittent arc initiation, to solve at least one of the following problems: (1) Most existing arc initiation technologies for VAR melting of titanium alloys use sponge titanium or titanium alloy shavings of the same grade as arc initiation material. Since the arc initiation material cannot be completely melted, it will cause the bottom of the ingot to be embedded or segregated, and in severe cases, it will penetrate the bottom of the crucible and cause a safety accident; (2) The use of a bottom pad in the crucible can reduce the cooling intensity of the bottom of the ingot, prevent the molten electrode from dripping onto the bottom pad and causing high melting point metal to form inclusions and damage the crucible base. Moreover, the process of preparing the bottom pad is cumbersome and complicated.

[0006] The objective of this invention is mainly achieved through the following technical solutions:

[0007] No arc-starting material or base pad is required. The process involves intermittent preheating of the crucible bottom and arc initiation of the consumable electrode under low current and low voltage conditions. The process is as follows: arc initiation → holding → power off → arc initiation → holding → power off → arc initiation → holding → normal arc initiation and melting (the number and values ​​of arc initiation, holding and power off are related to the specifications of the consumable electrode and the number of melting cycles).

[0008] The first aspect of the present invention provides a method for intermittent arc initiation, the method comprising:

[0009] S1. One-time melting: After welding the auxiliary electrode to the consumable electrode, perform n arc initiation, n holding, and n power off, where n is 2-3, and then perform the (n+1)th arc initiation and (n+1)th holding.

[0010] S2. Increase the arc ignition current and / or arc ignition voltage; perform this operation m times, where m is 2-3. After each increase in arc ignition current and arc ignition voltage, maintain the current and voltage, and then perform the first melting to obtain one ingot.

[0011] S3, Secondary Melting: After the primary ingot undergoes the first treatment, the auxiliary electrode is sequentially welded to the two primary ingots, and the process of arc initiation, holding, and power outage is performed for the n'th time; n' is 2-3, and then the process of arc initiation and holding for the n'+1th time is performed.

[0012] S4. Increase the arc-starting current and arc-starting voltage and perform this operation m' times, where m' is 3-4. After each increase in arc-starting current and arc-starting voltage, maintain the current and voltage, and then perform a second melting to obtain a secondary ingot.

[0013] S5. Three-stage melting: After the secondary ingot is processed, the auxiliary electrode is welded to the secondary ingot. The process involves the n”th arc initiation, the n”th holding, and the n”th power-off, where n” is 2-3. Then the process involves the n”+1th arc initiation and the n”+1th holding.

[0014] S6. Increase the arc ignition current and / or arc ignition voltage; perform this operation m” times, where m” is 3-4. After each increase in arc ignition current and arc ignition voltage, maintain the current and voltage, and then perform a third melting process to obtain three ingots.

[0015] Furthermore, the conditions for the nth arc initiation include: a current of 3-4 kA and a voltage of 27-29 V.

[0016] Furthermore, the holding time for the nth time is 2-3 minutes, and the power-off time for the nth time is 20-40 seconds.

[0017] Furthermore, the conditions for the (n+1)th arc initiation and the nth arc initiation are independently included: the arc initiation current is 3-4kA, the arc initiation voltage is 27-29V, and the holding time for the (n+1)th arc initiation is 3-5min.

[0018] Furthermore, in step S2, the conditions for the first arc initiation current include: an arc initiation current of 19-26kA, an arc initiation voltage of 33-37V, and a holding time of 4-6 minutes.

[0019] Furthermore, the arc-starting current of the mth arc is greater than or equal to the arc-starting current of the (m-1)th arc, and the arc-starting voltage of the mth arc is greater than or equal to the arc-starting voltage of the (m-1)th arc.

[0020] Furthermore, the arc-starting current of the mth arc is 105-120% of the current of the (m-1)th arc, and the arc-starting voltage of the mth arc is 100-110% of the voltage of the (m-1)th arc.

[0021] Furthermore, the holding time for the m-th arc initiation is 8-15 minutes.

[0022] Furthermore, the conditions for the n'th arc initiation include: an arc initiation current of 4-5 kA and an arc initiation voltage of 27-29 V.

[0023] Furthermore, the holding time for the n'th time is 2-3 minutes, and the power-off time for the n'th time is 20-40 seconds.

[0024] Furthermore, the current of the n'th arc initiation is 120-130% of the current of the nth arc initiation, and the voltage of the n'th arc initiation is 100-105% of the voltage of the nth arc initiation.

[0025] Furthermore, the conditions for the (n'+1)th arc initiation include: an arc initiation current of 3-4 kA, an arc initiation voltage of 27-29 V, and a (n'+1)th holding time of 3-6 min.

[0026] Furthermore, in step S4, the first and second improvements to the arc initiation conditions each independently include: an arc initiation current of 19-26kA, an arc initiation voltage of 33-38V, and a holding time of 6-8 minutes.

[0027] Furthermore, the arc-starting current of the m'th arc is 90-115% of the arc-starting current of the m'-1th arc, and the arc-starting voltage of the m'th arc is 100-105% of the arc-starting voltage of the m'-1th arc.

[0028] Furthermore, the holding time for the m'th time is 3-10 minutes.

[0029] Furthermore, the conditions for the nth arc initiation include: an arc initiation current of 4-5 kA and an arc initiation voltage of 27-29 kA.

[0030] Furthermore, the holding time for the nth time is 2-3 minutes, and the power-off time for the nth time is 20-40 seconds.

[0031] Furthermore, in step S6, the first and second improvements to the arc initiation conditions each independently include: an arc initiation current of 22-31kA, an arc initiation voltage of 33-38V, and a holding time of 6-10 minutes.

[0032] Furthermore, the arc-starting current of the m”th arc is less than the arc-starting current of the m”-1th arc, and the arc-starting voltage of the m”th arc is greater than or equal to the arc-starting voltage of the m”-1th arc.

[0033] Furthermore, the arc-starting current of the m”th arc is 90-120% of the current of the m”-1th arc, and the arc-starting voltage of the m”th arc is 100-105% of the voltage of the m”-1th arc.

[0034] Furthermore, the holding time for the m”th arc initiation is 4-12 minutes.

[0035] A second aspect of the present invention provides an ingot obtained by the method described in the first aspect.

[0036] The third aspect of this invention provides an application of the ingot described in the second aspect in titanium alloy smelting.

[0037] Compared with the prior art, the present invention can achieve at least one of the following beneficial effects:

[0038] 1. This invention uses a process of intermittent preheating of the crucible bottom under low current and low voltage conditions and arc initiation by consumable electrode, that is, repeating "arc initiation → holding → power off" multiple times before arc initiation → holding → normal arc initiation melting. This process does not require the use of arc-initiating material, which can eliminate the quality problems of ingot inclusion or segregation at the bottom of the ingot caused by arc-initiating material. The resulting ingot has a uniform composition without segregation, and the composition of the ingot head, middle and tail is uniform, without defects such as porosity and cracks.

[0039] 2. Compared with the existing technology of preparing a base pad to prevent damage to the crucible base from the melting of high-melting-point metal electrodes, the arc-starting process of the present invention is simple and easy to operate, eliminating the cumbersome process of base pad preparation and removal after melting.

[0040] 3. The arc-starting process of the present invention can prevent arc-starting during melting under normal working arc-starting current and voltage, and instantaneous arc damage to the bottom of the crucible, thereby improving production safety.

[0041] Other features and advantages of the invention will be set forth in the description which follows, and will be apparent in part from the description, or may be learned by practicing the invention. The objects and other advantages of the invention may be realized and obtained by means of what is particularly pointed out in the written description and the accompanying drawings. Attached Figure Description

[0042] The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. Throughout the drawings, the same reference numerals denote the same parts.

[0043] Figure 1 A schematic diagram showing the sampling locations for detecting the composition content of ingots.

[0044] Figure 2 A schematic diagram of 9 sampling points on the bottom end face for detecting the metal content of ingots. Detailed Implementation

[0045] The preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings, which form part of the present invention and, together with the embodiments of the present invention, serve to illustrate the principles of the present invention.

[0046] The first aspect of the present invention provides a method for intermittent arc initiation, the method comprising:

[0047] S1. One-time melting: After welding the auxiliary electrode to the consumable electrode, perform n arc initiation, n holding, and n power off, where n is 2-3, and then perform the (n+1)th arc initiation and (n+1)th holding.

[0048] S2. Increase the arc ignition current and / or arc ignition voltage; perform this operation m times, where m is 2-3. After each increase in arc ignition current and arc ignition voltage, maintain the current and voltage, and then perform the first melting to obtain one ingot.

[0049] S3, Secondary Melting: After the primary ingot undergoes the first treatment, the auxiliary electrode is sequentially welded to the two primary ingots, and the process of arc initiation, holding, and power outage is performed for the n'th time; n' is 2-3, and then the process of arc initiation and holding for the n'+1th time is performed.

[0050] S4. Increase the arc-starting current and arc-starting voltage and perform this operation m' times, where m' is 3-4. After each increase in arc-starting current and arc-starting voltage, maintain the current and voltage, and then perform a second melting to obtain a secondary ingot.

[0051] S5. Three-stage melting: After the secondary ingot is processed, the auxiliary electrode is welded to the secondary ingot. The process involves the n”th arc initiation, the n”th holding, and the n”th power-off, where n” is 2-3. Then the process involves the n”+1th arc initiation and the n”+1th holding.

[0052] S6. Increase the arc ignition current and / or arc ignition voltage; perform this operation m” times, where m” is 3-4. After each increase in arc ignition current and arc ignition voltage, maintain the current and voltage, and then perform a third melting process to obtain three ingots.

[0053] In this invention, in step S1, the value of n is related to the specifications of the consumable electrode. When the specifications of the consumable electrode are smaller than... When n is 2, the self-consumable electrode specification is greater than or equal to n is 3.

[0054] In this invention, in step S2, the value of m is related to the specifications of the consumable electrode. When the specifications of the consumable electrode are smaller than... m is 2, when the self-consumable electrode specification is greater than or equal to m is 3.

[0055] In this invention, in step S3, the value of n' is related to the specifications of the primary ingot. When the specifications of the primary ingot are smaller than... n' is 2, when the size of a single ingot casting is greater than or equal to... n' is 3.

[0056] In this invention, in step S4, the value of m' is related to the specifications of the primary ingot casting. When the specifications of the primary ingot casting are smaller than... m' is 3, when the size of a single casting ingot is greater than or equal to m' is 4.

[0057] In this invention, in step S5, the value of n” is related to the specifications of the secondary ingot. When the specifications of the secondary ingot are smaller than... n" is 2, and the secondary casting ingot specification is greater than or equal to n” is 3.

[0058] In this invention, in step S6, the value of "m" is related to the specifications of the secondary ingot. When the specifications of the secondary ingot are smaller than... m” is 3, and the secondary casting ingot specification is greater than or equal to m” is 4.

[0059] In this invention, when the number of arc initiation times in each step meets the above-mentioned range, the requirement for stable arc combustion during the welding process can be met, thereby ensuring a safe and smooth transition to the subsequent melting stage.

[0060] According to the present invention, the current for the n'th arc initiation is 120-130% of the current for the nth arc initiation, and the voltage for the n'th arc initiation is 100-105% of the voltage for the nth arc initiation. This allows the consumable electrode to be gradually preheated, increasing the temperature of the cathode region, thereby improving the splashing and instability during the droplet transfer process and making the arc initiation process more stable.

[0061] According to the present invention, the arc initiation current of the n”th arc initiation current and the arc initiation current of the n'th arc initiation current are each independently 4-5kA, and the two can be the same or different, but preferably the same.

[0062] According to the present invention, the arc voltage of the n”th arc initiation and the arc voltage of the n'th arc initiation are each independently 27-29kA. They can be the same or different, but are preferably the same.

[0063] This invention employs an intermittent arc-initiating method, namely, arc initiation → holding → power off → arc initiation → holding → power off → arc initiation → holding → normal increase of arc initiation current and voltage. This method avoids the crucible base being burned due to the instantaneous strong current during arc initiation, thus preventing contamination of the molten metal. Furthermore, since this method eliminates the need for arc-starting material, it avoids incomplete melting of the arc-starting material, which could lead to under-casting or segregation at the bottom of the ingot. This invention sets a relatively small arc initiation current and voltage and then disconnects the power, gradually increasing the arc initiation current and voltage afterward. This approach avoids damaging the bottom of the crucible and eliminates the influence of the arc-starting material on the uniformity of the ingot composition.

[0064] In this invention, it can be understood that n arc initiations, n holdings, and n power outages refer to performing n "arc initiation → holding → power outage" operations.

[0065] In this invention, in step S1, specifically, the consumable electrode is prepared by the following method: raw materials with elemental contents meeting the following percentages are batched, mixed, and pressed according to a mass ratio to form several electrode blocks, which are then welded into consumable electrodes. Each electrode block weighs 102-110 kg and has a density ≥3.4 g / cm³. 3 Specifically, the elemental percentages in the raw materials are: Al: 5.5-6.5%, Nb: 2.5-3.5%, Zr: 1.5-2.5%, Mo: 0.6-1.5%, Fe: ≤0.25%, O: 0.10% ≤0.15%, with the balance being Ti and unavoidable impurities. The sources of the above elements may include: grade 0 sponge titanium, Ti50Nb alloy (Nb content is 49-51%, balance is Ti), Al-60Mo alloy (Mo content is 60-70%, balance is Al), sponge zirconium, aluminum briquettes, iron nails, and titanium dioxide.

[0066] In this invention, in step S1, specifically, the consumable electrode can be prepared under the following conditions: the consumable electrode is welded using a vacuum plasma welding box, with an argon gas pressure of 10000-25000Pa, a welding current of 350-370A, a welding voltage of 40-48V, and a cooling time of >30min.

[0067] In this invention, in step S1, considering the issues of ensuring stable ingot quality and smelting safety, during a single smelting operation, the furnace vacuum degree is ensured to be ≤0.7Pa and the leakage rate is ≤0.8Pa / min before smelting.

[0068] According to the present invention, in step S1, specifically considering that under the action of a large current, the crystallizer base is prone to burnout and contamination of the molten metal, and may also cause crystallizer breakage leading to a safety accident, the conditions for controlling the nth arc initiation include: an arc initiation current of 3-4 kA and an arc initiation voltage of 27-29 V. Only in this way can production safety be guaranteed.

[0069] According to the present invention, in step S1, specifically, the holding time for the nth time is 2-3 minutes, and the power-off time for the nth time is 20-40 seconds, so that the electric arc will not damage the bottom of the crucible due to high temperature.

[0070] In this invention, specifically in step S1, considering the heat required for melting the consumable electrode, and to prevent it from melting by gradually increasing the temperature from room temperature, the "arc ignition → holding → power off" operation needs to be performed at least n times. Further, n is controlled to be greater than 1, preferably 2-3. If it is less than 1 time, subsequent increases in the arc ignition current and voltage will damage the crucible bottom pad, failing to achieve the preheating effect. If it is greater than 3 times, the consumable electrode will partially melt and solidify to form a sandwich layer under water cooling.

[0071] In this invention, in step S1, considering that a large arc-starting current and voltage would damage the bottom of the crucible, the conditions for the (n+1)th arc-starting and the nth arc-starting are independently defined as follows: the arc-starting current is 3-4 kA and the arc-starting voltage is 27-29 V. The arc-starting current and voltage for the (n+1)th arc-starting can be the same as or different from those for the nth arc-starting, but are preferably the same.

[0072] In this invention, considering that the temperature of the consumable electrode has already reached a high level due to preheating during the preceding arc-starting process, the holding time for the (n+1)th time is controlled to be 3-5 minutes. Preferably, the holding time for the (n+1)th time is longer than the holding time for the nth time. In this way, the temperature of the consumable electrode can be increased significantly without damaging the crucible bottom pad.

[0073] In this invention, specifically in step S2, the arc-starting current is first increased to A1 while the arc-starting voltage is simultaneously increased to V1, and this current and voltage condition is maintained for 4-6 minutes, where A1 is 19-26 kA and V1 is 33-37 V. In this invention, the first increase in arc-starting current and arc-starting voltage, respectively, within the aforementioned ranges, enables the consumable electrode temperature to rise, synergizing with the subsequent first melting stage to ensure its smooth progress, improve production stability, and enhance the compositional uniformity of the ingot obtained in one operation.

[0074] In this invention, considering the heat required for the consumable electrode to reach its melting point, the arc current and / or arc voltage are intermittently increased m times. Furthermore, by controlling m to be greater than 1, the temperature of the cathode region of the consumable electrode and the anode region of the crucible can be intermittently increased to prevent the melting temperature from being reached in one step and the normal melting stage from not being able to be entered smoothly, which would pose a significant safety risk. Preferably, m is an integer from 2 to 3.

[0075] In this invention, considering the heat required for the consumable electrode to reach its melting point, the arc ignition current and / or arc ignition voltage are increased in stages. The arc ignition current of the mth time is greater than or equal to the arc ignition current of the (m-1)th time, and the arc ignition voltage of the mth time is greater than or equal to the arc ignition voltage of the (m-1)th time. In this way, the temperature of the cathode region of the consumable electrode and the anode region of the crucible can be increased in stages, avoiding reaching the melting temperature in one step, which would prevent a smooth transition to the first melting stage and pose a significant safety risk.

[0076] According to a preferred embodiment of the present invention, the arc-starting current of the mth time is 105-120% of the current of the (m-1)th time, so as to steadily increase the temperature of the cathode region of the consumable electrode and the anode region of the crucible, enter the normal melting stage, and reduce the safety problems caused by the arc-starting process.

[0077] According to a preferred embodiment of the present invention, the arc-starting voltage of the mth time is 100-110% of the voltage of the (m-1)th time, so as to steadily increase the temperature of the cathode region of the consumable electrode and the anode region of the crucible, enter the normal melting stage, and reduce the safety problems caused by the arc-starting process.

[0078] According to the present invention, the holding time of the m-th arc initiation is greater than the holding time of the (m-1)-th arc initiation. This allows for a smooth increase in the temperature of the consumable electrode cathode region and the crucible anode region, thus enabling the transition to the normal melting stage.

[0079] According to a preferred embodiment of the present invention, the holding time for the m-th arc initiation is 8-15 minutes.

[0080] In this invention, in step S2, the holding time of the (m-1)th arc initiation is greater than the holding time of the (n+1)th arc initiation. In this way, the temperature of the consumable electrode cathode region and the crucible anode region can be steadily increased, and the normal melting stage can be entered.

[0081] In this invention, the conditions for the first melting include: under vacuum, at a temperature not less than 5 × 10⁻⁶. -1 Melting is carried out under the following conditions: vacuum level of Pa, arc voltage of 33-37V, arc current of 17-22kA, and arc spacing of 25-35mm.

[0082] In this invention, in step S3, the first process includes cleaning and flattening the ingot, specifically including: using an ingot cleaning machine to remove foreign matter from the ingot surface, and using a lathe to machine flatten the ingot crown of the primary ingot.

[0083] According to the present invention, specifically, the current for the n'th arc initiation is 4-5kA and the voltage is 27-29V. Preferably, the current for the n'th arc initiation is greater than the current for the nth arc initiation, so as to avoid the crucible base from burning and contaminating the molten metal, resulting in ingot undercut or segregation at the bottom of the ingot.

[0084] According to the present invention, considering the stability of subsequent melting processes, the holding time of the n'th time is controlled to be the same as the holding time of the nth time, specifically 2-3 minutes, and the power-off time of the n'th time is controlled to be the same as the power-off time of the nth time, specifically 20-40 seconds. This allows for slow preheating, avoiding excessively short preheating times under low current and low voltage conditions, which could lead to poor connection with subsequent melting processes and reduce melting stability.

[0085] In this invention, specifically in step S3, during the secondary melting process, considering the need for stable arc combustion, the "arc ignition → holding → power off" operation needs to be performed at least n' times. Furthermore, controlling n' to be 2-3 ensures that the requirement for stable arc combustion during welding is met.

[0086] In this invention, in step S3, the conditions for the (n'+1)th arc initiation and the conditions for the n'th arc initiation each independently include: a current of 3-4 kA and a voltage of 27-29 V. The arc initiation current and voltage for the (n'+1)th arc initiation are the same as, or different from, the arc initiation current and voltage for the n'th arc initiation, but are preferably the same.

[0087] In this invention, the holding time for the (n'+1)th melting point is 3-6 minutes, preferably longer than the holding time for the (n')th melting point. This ensures a smooth transition to the subsequent second melting process and improves the uniformity of the final ingot.

[0088] In this invention, in step S3, considering the issue of ingot uniformity, during the secondary melting, the furnace vacuum degree is ensured to be ≤0.6Pa and the leakage rate is ≤0.7Pa / min before melting. This helps to maintain the stability of the alloy composition and thus improve the uniformity of the ingot composition.

[0089] In this invention, specifically in step S4, the arc-starting current is first increased to A2 while the arc-starting voltage is simultaneously increased to V2, and this current and voltage condition is maintained for 6-8 minutes, where A2 is 19-26 kA and V2 is 33-38 V. The arc-starting current is then increased to A2 while the arc-starting voltage is simultaneously increased to V2, and this current and voltage condition is maintained for 6-8 minutes, where A2 is 19-26 kA and V2 is 33-38 V. In this invention, the first and second increases in arc-starting current and arc-starting voltage respectively meet the aforementioned ranges, which can coordinate with the aforementioned processes to avoid the instantaneous strong current during arc-starting causing the crucible base to burn out and thus contaminating the molten metal.

[0090] In this invention, the operation of increasing the arc current and / or arc voltage is performed m' times. Furthermore, controlling m' to be 3-4 can ensure that the heat of the arc can be evenly transferred to the arc area, while removing or diluting impurities, thereby reducing the formation of inclusions and improving the uniformity of the ingot composition.

[0091] In this invention, the arc-starting current of the m'th arc is greater than or equal to the arc-starting current of the m'-1th arc, and the arc-starting voltage of the m'th arc is greater than or equal to the arc-starting voltage of the m'-1th arc. This enables uniform preheating, reduces heat loss during the arc-starting process, and thus reduces the cooling rate at the bottom of the ingot, thereby reducing the risk of incomplete casting.

[0092] According to a preferred embodiment of the present invention, the arc-starting current of the m'th time is 90-115% of the current of the m'-1th time, which can ensure that the subsequent second melting is more stable, thereby making the second ingot casting more uniform.

[0093] According to a preferred embodiment of the present invention, the arc-starting voltage of the m'th time is 100-105% of the voltage of the m'-1th time, which can further improve the uniformity of the ingot composition.

[0094] According to the present invention, the holding time of the m'th arc initiation is greater than the holding time of the m'-2th arc initiation. This ensures a more stable second melting process, resulting in a more uniform ingot.

[0095] According to a preferred embodiment of the present invention, the holding time for the m'th arc initiation is 3-10 minutes.

[0096] In this invention, the conditions for the second melting include: under a vacuum atmosphere, at a temperature not less than 5 × 10⁻⁶. -1 Melting is carried out under the following conditions: vacuum level of Pa, arc voltage of 33-39V, arc current of 17-28kA, and arc electrode spacing of 30-40mm.

[0097] In this invention, in step S5, the second process includes cleaning and flattening the secondary ingot, specifically including: using an ingot cleaning machine to remove foreign matter from the surface of the ingot, and using a lathe to machine and flatten the ingot crown of the secondary ingot.

[0098] According to the present invention, the current for the n”th arc initiation and the current for the n'th arc initiation can be the same or different, but preferably the same.

[0099] Specifically, the current for the n”th arc initiation and the current for the n'th arc initiation are each independently 4-5kA, and the voltage is 27-29V. In this way, the uniformity of the ingot can be improved while ensuring production safety.

[0100] According to the present invention, the holding time of the n”th time is controlled to be the same as the holding time of the n'th time, specifically 2-3 minutes, and the power-off time of the n”th time is controlled to be the same as the power-off time of the n'th time, specifically 20-40 seconds. This makes the subsequent third melting process smoother, thereby ensuring that the crucible is not damaged and improving the uniformity of the composition of the three ingots.

[0101] In this invention, specifically in step S5, the "arc ignition → holding → power off" operation needs to be performed at least n” times during the three melting processes. Further, controlling n” to be 2-3 ensures that the requirement for stable arc combustion during welding is met, thus allowing for a safe and smooth transition to subsequent melting processes.

[0102] In this invention, the holding time for the (n'+1)th time is 3-4 minutes, preferably longer than the holding time for the (n')th time. This prevents the electric arc from damaging the bottom of the crucible due to high temperature, ensuring production safety.

[0103] In this invention, specifically in step S6, the arc-starting current is first increased to A3 while the arc-starting voltage is simultaneously increased to V3, and this current and voltage condition is maintained for 6-10 minutes, where A3 is 22-31 kA and V3 is 33-38 V. This first increase in arc-starting current and arc-starting voltage, satisfying the aforementioned ranges, enables the consumable electrode temperature to rise, synergizing with the subsequent second melting process to ensure the smooth progress of the second melting stage, improving production stability and the compositional uniformity of the resulting ingot.

[0104] In this invention, the operation of increasing the arc current and / or arc voltage is performed m” times. Furthermore, controlling m” to be 3-4 can meet the requirements for stable arc combustion during the welding process, thereby safely and smoothly connecting to the subsequent third melting stage.

[0105] In this invention, the arc-starting current of the m”th arc is less than the arc-starting current of the m”-1th arc, and at the same time, the arc-starting voltage of the m”th arc is greater than or equal to the arc-starting voltage of the m”-1th arc. This reduces the heat loss generated during the arc-starting process, thereby reducing the cooling rate at the bottom of the ingot and reducing the risk of inclusions.

[0106] According to a preferred embodiment of the present invention, the arc-starting current of the m”th time is 90-120% of the current of the m”-1th time, which can ensure that the subsequent third melting is more stable, thereby making the composition of the three ingots more uniform.

[0107] According to a preferred embodiment of the present invention, the arc-starting voltage of the m”th time is 100-105% of the voltage of the m”-1th time. This can work in conjunction with the aforementioned arc-starting current to ensure that the subsequent third melting is more stable, thereby making the composition of the three ingots more uniform.

[0108] According to the present invention, the holding time of the m”th arc initiation is greater than the holding time of the m”-2th arc initiation. This ensures a more stable third melting process, resulting in a more uniform ingot composition.

[0109] According to a preferred embodiment of the present invention, the holding time for the m”th arc initiation is 4-12 minutes.

[0110] In this invention, in step S6, considering the uniformity of gas element content in the finished ingot and the stability of the smelting process, during the three smelting processes, it is ensured that the vacuum degree of the furnace body is ≤0.5Pa and the leakage rate is ≤0.6Pa / min before smelting. Only in this way can the composition of the ingot be uniform and the quality of the ingot be accurately controlled.

[0111] In this invention, the method further includes: performing a peeling inspection on the tertiary ingot obtained from the third melting process. For example, a lathe can be used to peel the tertiary ingot until there are no large-area porosity defects on the surface, and then the inspection is performed. Specifically, the inspection can be performed as follows: test samples are taken from approximately 250-270 mm away from the ingot head and tail, respectively, with a sampling depth of 10-20 mm. The content of metal elements and gaseous elements in each part of the sample is detected using an inductively coupled plasma atomic emission spectrometer and an oxygen and nitrogen measuring instrument, respectively. At the same time, a non-destructive ultrasonic flaw detector is used to detect internal defects (such as porosity and cracks) in the sample and to determine the riser position.

[0112] According to a particularly preferred embodiment of the present invention, the method includes:

[0113] S1. First Melting: Before melting, the furnace vacuum degree is ≤0.7Pa and the leakage rate is ≤0.8Pa / min. The arc ignition process is as follows: First arc ignition current is 3-3.5kA, first arc ignition voltage is 27-28V, first holding time is 2-3min, and first power off time is 25-30s; Second arc ignition current is 3-3.5kA, second arc ignition voltage is 27-28V, second holding time is 2-3min, and second power off time is 25-30s; Then, a third arc ignition is performed, with a third arc ignition current of 3-4kA, a third arc ignition voltage of 27-28V, and a third holding time of 3-4min.

[0114] S2. Increase the arc-starting current to 19-20kA and the arc-starting voltage to 35-36V, and maintain this arc-starting current and voltage for 6-8 minutes. Then, increase the arc-starting current to 21-22kA and the arc-starting voltage to 35-36V for a second time, and maintain this for 12-15 minutes. Then, under vacuum conditions, apply an arc-starting voltage of not less than 5 × 10⁻⁶ kA. -1 The first melting is carried out under the following conditions: vacuum degree of Pa, arc voltage of 33-37V, arc current of 17-22kA, and arc spacing of 25-35mm to obtain a first ingot.

[0115] S3. Secondary Melting: The surface of the primary ingot is cleaned using an ingot cleaning machine to remove foreign matter. The ingot crown of the primary melting ingot is machined and leveled using a lathe. Before melting, the furnace vacuum degree is ≤0.6Pa and the leakage rate is ≤0.7Pa / min. The arc ignition process is as follows: First arc ignition current 4-4.5kA, first arc ignition voltage 27-28V, first hold 2-3min, first power off 25-30s; Second arc ignition current 4-4.5kA, second arc ignition voltage 27-28V, second hold 2-3min, second power off 25-30s; Then, a third arc ignition is performed, with the third arc ignition current 4-4.5kA, the third arc ignition voltage 27-28V, and the third hold time 5-8min.

[0116] S4. First, increase the arc-starting current to 20-21kA and the arc-starting voltage to 35-36V, and maintain this arc-starting current and voltage for 5-8 minutes. Second, increase the arc-starting current to 21-22kA and the arc-starting voltage to 35-36V, and maintain this arc-starting current and voltage for 4 minutes. Third, increase the arc-starting current to 22-23kA and the arc-starting voltage to 35-36V, and maintain this arc-starting current and voltage for 8-12 minutes. Then, under a vacuum atmosphere, at a temperature not less than 5 × 10⁻⁶ kJ / L... -1 A second melting process is carried out under the following conditions: vacuum degree of Pa, arc voltage of 33-38V, arc current of 18-27kA, and arc electrode spacing of 30-40mm to obtain a secondary ingot.

[0117] S5. Third Melting: The secondary ingot is cleaned of surface impurities using an ingot cleaning machine. The ingot crown is machined and leveled using a lathe. Before melting, the furnace vacuum degree is ≤0.5Pa and the leakage rate is ≤0.6Pa / min. The arc-starting process is as follows: First arc-starting current 4-5kA, first arc-starting voltage 27-28V, first holding time 2-3min, first power-off time 25-30s; Second arc-starting current 4-5kA, second arc-starting voltage 27-28V, second holding time 2-3min, second power-off time 25-30s; Then, a third arc-starting process is performed, with a third arc-starting current of 4-5kA, a third arc-starting voltage of 27-28V, and a third holding time of 5-10min.

[0118] S6. First, increase the arc-starting current to 22-23kA and the arc-starting voltage to 35-26V, and maintain this arc-starting current and voltage for 8-10 minutes. Second, increase the arc-starting current to 27-28kA and the arc-starting voltage to 35-36V, and maintain this arc-starting current and voltage for 4 minutes. Third, increase the arc-starting current to 25-26kA and the arc-starting voltage to 35-36V, and maintain this arc-starting current and voltage for 8-10 minutes. Then, in a vacuum atmosphere, at a temperature not less than 5×10⁻⁶ kJ / L... -1 The third melting is carried out under the following conditions: vacuum degree of Pa, arc voltage of 34-40V, arc current of 21-30kA, and arc electrode spacing of 30-40mm to obtain the third ingot. The third ingot is then peeled off on a lathe until there are no large areas of pores on the surface to obtain the final ingot.

[0119] Among them, the current of the n'th arc initiation is 125-135% of the current of the nth arc initiation;

[0120] Among them, the arc-starting current of the mth time is 105-120% of the current of the (m-1)th time;

[0121] Among them, the arc-starting current of the m'th time is 102-103% of the current of the m'-1th time;

[0122] Among them, the arc-starting current of the m”th time is 90-95% of the current of the m”-1th time.

[0123] A second aspect of the present invention provides an ingot obtained by the method described in the first aspect.

[0124] In this invention, the ingot has a uniform composition without segregation, the range of alloy element content at various points of the ingot is no higher than 0.3%, and the difference in phase transformation temperature between the two ends of the ingot is less than 10°C.

[0125] The third aspect of this invention provides an application of the ingot described in the second aspect in titanium alloy smelting.

[0126] The advantages of precise control of process parameters of the present invention will be demonstrated below with specific embodiments and comparative examples.

[0127] Example 1

[0128] To produce Taking TA31 ingot as an example, the element content meets the following requirements: Al: 6.2%, Nb: 3.1%, Zr: 2.1%, Mo: 1.18%, Fe: 0.025%, O: 0.10%, with the balance being Ti and unavoidable impurities.

[0129] S1. Using grade 0 sponge titanium, Ti50Nb alloy (Nb content 50%, balance Ti), Al-60Mo alloy (Mo content 60%, balance Al), sponge zirconium, aluminum briquettes, and titanium dioxide as raw materials, according to the mass ratio in Table 1, several identical electrode blocks are prepared, mixed, and pressed to form consumable electrodes. Each electrode block weighs 102-110 kg and has a density ≥3.4 g / cm³. 3 ;

[0130] Table 1

[0131] Raw material name Ingredient weight ratio Titanium sponge 84.25％ Ti50Nb alloy 5.98％ Aluminum Bean 5.56％ Al-60Mo alloy 1.91％ sponge zirconium 2.15％ Titanium dioxide 0.15％

[0132] Consumable electrodes were welded using a vacuum plasma welding box with an argon gas pressure of 15640Pa, a welding current of 350-370A, a welding voltage of 40-48V, and a cooling time of >30min.

[0133] One-time smelting: using The consumable electrode is placed in the crucible and then welded to the auxiliary electrode using in-furnace welding. Before melting, the furnace vacuum degree is ≤0.7Pa and the leakage rate is ≤0.8Pa / min. The arc initiation process is as follows: the first arc initiation current is 3kA, the first arc initiation voltage is 28V, the first holding time is 2min, and the first power-off time is 30s; the second arc initiation current is 3kA, the second arc initiation voltage is 28V, the second holding time is 2min, and the second power-off time is 30s; then the third arc initiation is performed with a third arc initiation current of 3kA, a third arc initiation voltage of 28V, and a third holding time of 3min.

[0134] S2. Increase the arc ignition current to 20kA and the arc ignition voltage to 36V, and maintain the above arc ignition current and arc ignition voltage for 8 minutes. Then, increase the arc ignition current to 22kA and the arc ignition voltage to 36V for the second time, and maintain the voltage for 15 minutes. Then, carry out the first melting under the conditions of vacuum degree ≤0.5Pa, current of 18-19kA and voltage of 33-34V to obtain a first ingot.

[0135] S3. Secondary Melting: The surface of the primary ingot is cleaned using an ingot cleaning machine to remove foreign matter. The ingot crown of the primary melted ingot is then machined and leveled using a lathe. The consumable electrode is placed in the crucible and then welded to the two primary ingots sequentially using in-furnace welding. Before melting, the furnace vacuum degree is ≤0.6Pa and the leakage rate is ≤0.7Pa / min. The specific process is as follows: the first arc-starting current is 4kA, the first arc-starting voltage is 28V, the first holding time is 2min, and the first power-off time is 30s; the second arc-starting current is 4kA, the second arc-starting voltage is 28V, the second holding time is 2min, and the second power-off time is 30s; then the third arc-starting current is 4kA, the third arc-starting voltage is 28V, the third holding time is 5min.

[0136] S4. First, increase the arc-starting current to 20kA and the arc-starting voltage to 35V, and maintain this arc-starting current and voltage for 6 minutes. Second, increase the arc-starting current to 22kA and the arc-starting voltage to 35V, and maintain this arc-starting current and voltage for 4 minutes. Third, increase the arc-starting current to 22.5kA and the arc-starting voltage to 36V, and maintain this arc-starting current and voltage for 10 minutes. Then, under conditions of vacuum ≤0.5Pa, current 19-20kA, and voltage 34-35V, perform a second melting to obtain a secondary ingot.

[0137] S5. Third Melting: The secondary ingot is cleaned of surface impurities using an ingot cleaning machine, and the ingot crown is machined and leveled using a lathe. The consumable electrode is placed in the crucible and then welded to the secondary ingot using in-furnace welding. Before melting, the furnace vacuum degree is ≤0.5Pa and the leakage rate is ≤0.6Pa / min. The specific process is as follows: the first arc-starting current is 4kA, the first arc-starting voltage is 28V, the first holding time is 2min, and the first power-off time is 30s; the second arc-starting current is 4kA, the second arc-starting voltage is 28V, the second holding time is 2min, and the second power-off time is 30s; then the third arc-starting current is 4kA, the third arc-starting voltage is 28V, the third holding time is 5min.

[0138] S6. First, increase the arc-starting current to 23kA and the arc-starting voltage to 35V, and maintain this for 8 minutes. Second, increase the arc-starting current to 27kA and the arc-starting voltage to 35V, and maintain this for 4 minutes. Third, increase the arc-starting current to 25kA and the arc-starting voltage to 35V, and maintain this for 8 minutes. Then, under conditions of vacuum ≤0.5Pa, current 22-23kA, and voltage 34-35V, perform a third melting to obtain a third ingot. Use a lathe to peel off the surface of the third ingot until there are no large areas of pores.

[0139] To detect the composition content of the obtained ingot, samples were taken at the following locations: 200-250mm from the ingot head (referred to as "upper" in Table 2, and the specific sampling location in Example 1 of this invention is 200mm from the ingot head); 200-250mm from the ingot tail (referred to as "lower" in Table 2, and the specific sampling location in Example 1 of this invention is 200mm from the ingot tail); and at the midpoint between the "upper" and "lower" parts of the ingot (referred to as "middle" in Table 2). A schematic diagram of the sampling locations is shown below. Figure 1 The sampling depth was 10 mm, and the results are shown in Table 2.

[0140] Table 2

[0141] Part superior middle Down Range Al 6.24 6.15 6.26 0.11 Nb 3.14 3.13 3.2 0.07 Zr 2.04 2.16 2.14 0.12 Mo 1.18 1.15 1.12 0.06 Fe 0.034 0.032 0.028 0.006 O 0.098 0.105 0.102 0.007 N 0.003 0.003 0.003 0 C 0.0098 0.0098 0.0081 0.0017

[0142] As can be seen from Table 2, the content of alloying elements in the upper, middle and lower parts of the entire ingot is relatively uniform, meeting the industry requirement that the composition difference of the ingot be ≤0.3%.

[0143] To further illustrate the impact of the intermittent arc-starting process on the composition of the ingot bottom, according to Figure 2 As shown in the figure, samples were taken at 9 points on the bottom end face of the ingot to test the metal content. The sampling depth was 10 mm. The results are shown in Table 3.

[0144] Table 3

[0145] Part Al Nb Zr Mo Fe 1 6.26 3.18 2.14 1.16 0.03 2 6.21 3.12 2.10 1.19 0.032 3 6.19 3.13 2.10 1.21 0.037 4 6.22 3.13 2.08 1.18 0.033 5 6.24 3.09 2.12 1.14 0.028 6 6.24 3.14 2.10 1.15 0.028 7 6.23 3.10 2.09 1.19 0.031 8 6.18 3.12 2.10 1.18 0.033 9 6.24 3.18 2.12 1.15 0.027 Range 0.08 0.09 0.06 0.07 0.01

[0146] As can be seen from Table 3, the range of the content of each metal element in different parts of the ingot is no greater than 0.01, indicating good uniformity.

[0147] Furthermore, referring to GB / T 23605-2020, the phase transformation temperatures at the upper and lower ends of the ingot are 985℃ and 995℃, respectively. This shows that the alloy element content at the upper and lower parts of the ingot has little impact on the phase transformation point, which also confirms the uniformity of the ingot composition.

[0148] Example 2

[0149] To produce Taking TC4 ingot as an example, the element content meets the following requirements: Al: 6.35%, V: 4.2%; Fe: 0.2%; O: 0.175%, with the balance being Ti and unavoidable impurities.

[0150] S1. Using grade 0 sponge titanium, AlV55 alloy (V content 55%, balance Al), aluminum briquettes, iron nails, and titanium dioxide as raw materials, according to the mass ratio in Table 4, several identical electrode blocks are prepared, mixed, and pressed to form consumable electrodes. Each electrode block weighs 130 kg and has a density of 3.4 g / cm³. 3 ;

[0151] Table 4

[0152] Raw material name Ingredient weight ratio Titanium sponge 88.60％ AlV55 alloy 7.21％ Aluminum Bean 3.43％ iron nails 0.17％ Titanium dioxide 0.33％

[0153] Consumable electrodes were welded using a vacuum plasma welding box with an argon gas pressure of 15900Pa, a welding current of 350-370A, a welding voltage of 40-48V, and a cooling time of >30min.

[0154] One-time smelting: using The crucible is used to load the consumable electrode into the furnace. The auxiliary electrode is welded to the consumable electrode using in-furnace welding. Before melting, the furnace vacuum degree is ≤0.7Pa and the leakage rate is ≤0.8Pa / min. The arc initiation process is as follows: the first arc initiation current is 4kA, the first arc initiation voltage is 28V, the first holding time is 2min, and the first power off time is 30s; the second arc initiation current is 4kA, the second arc initiation voltage is 28V, the second holding time is 2min, and the second power off time is 30s; then the third arc initiation is performed, the third arc initiation current is 4kA, the third arc initiation voltage is 28V, and the third holding time is 3min.

[0155] S2. First, increase the arc-starting current to 25kA and the arc-starting voltage to 36V, and maintain the arc-starting current and arc-starting voltage for 8 minutes. Then, increase the arc-starting current to 27kA and the arc-starting voltage to 36V, and maintain the arc-starting current and arc-starting voltage for 15 minutes. Other steps are the same as in Example 1, and a first ingot is obtained.

[0156] S3. Secondary Melting: The surface of the primary ingot is cleaned using an ingot cleaning machine to remove foreign matter. The ingot crown of the primary melted ingot is then machined and leveled using a lathe. The consumable electrode is placed in the crucible and then welded to the two primary ingots sequentially using in-furnace welding. Before melting, the furnace vacuum degree is ≤0.6Pa and the leakage rate is ≤0.7Pa / min. The specific process is as follows: the first arc-starting current is 4kA, the first arc-starting voltage is 28V, the first holding time is 2min, and the first power-off time is 30s; the second arc-starting current is 4kA, the second arc-starting voltage is 28V, the second holding time is 2min, and the second power-off time is 30s; then the third arc-starting current is 4kA, the third arc-starting voltage is 28V, the second holding time is 2min, and the second power-off time is 30s; then the third arc-starting current is 4kA, the third arc-starting voltage is 28V, and the third holding time is 6min.

[0157] S4. First, increase the arc-starting current to 26kA and the arc-starting voltage to 356V, and maintain this arc-starting current and voltage for 8 minutes. Second, increase the arc-starting current to 29kA and the arc-starting voltage to 36V, and maintain this arc-starting current and voltage for 10 minutes. Third, increase the arc-starting current to 27kA and the arc-starting voltage to 36V, and maintain this arc-starting current and voltage for 3 minutes. Other steps are the same as in Example 1, resulting in a secondary ingot.

[0158] S5. Third Melting: The secondary ingot is cleaned of surface impurities using an ingot cleaning machine, and the ingot crown is machined and leveled using a lathe. The consumable electrode is placed in the crucible and then welded to the secondary ingot using in-furnace welding. Before melting, the furnace vacuum degree is ≤0.5Pa and the leakage rate is ≤0.6Pa / min. The specific process is as follows: the first arc-starting current is 4kA, the first arc-starting voltage is 28V, the first holding time is 2min, and the first power-off time is 30s; the second arc-starting current is 4kA, the second arc-starting voltage is 28V, the second holding time is 2min, and the second power-off time is 30s; then the third arc-starting current is 4kA, the third arc-starting voltage is 28V, the third holding time is 5min.

[0159] S6. First, increase the arc-starting current to 31kA and the arc-starting voltage to 35V, and maintain the above arc-starting current and arc-starting voltage for 6 minutes. Second, increase the arc-starting current to 34kA and the arc-starting voltage to 36V, and maintain the above arc-starting current and arc-starting voltage for 4 minutes. Third, increase the arc-starting current to 33kA and the arc-starting voltage to 36V, and maintain the above arc-starting current and arc-starting voltage for 12 minutes. Other steps are the same as in Example 1. Three ingots are obtained, and the three ingots are peeled off with a lathe until there are no large areas of pores on the surface to obtain the ingot.

[0160] To detect the composition content of the obtained ingots, samples were taken at 240-260 mm from the ingot head and tail, respectively. The results are shown in Table 5.

[0161] Table 5

[0162] Part Al V Fe O N C superior 6.30 4.18 0.192 0.170 0.0049 0.0072 middle 6.33 4.19 0.195 0.172 0.0042 0.0069 Down 6.32 4.22 0.199 0.163 0.0039 0.009 Range 0.03 0.04 0.007 0.009 0.01 0.0018

[0163] As can be seen from Table 5, the content of alloying elements in the upper, middle and lower parts of the entire ingot is relatively uniform, meeting the industry requirement that the composition difference of the ingot be ≤0.3%.

[0164] To further illustrate the impact of the intermittent arc-starting process on the composition of the bottom of the ingot, samples were taken at 9 points on the bottom end face of the ingot to detect the metal content. The sampling depth was 10 mm. The results are shown in Table 6.

[0165] Table 6

[0166] Part Al V Fe 1 6.32 4.21 0.192 2 6.33 4.20 0.193 3 6.30 4.18 0.201 4 6.32 4.19 0.195 5 6.33 4.22 0.192 6 6.33 4.22 0.193 7 6.31 4.21 0.197 8 6.33 4.20 0.196 9 6.32 4.22 0.191 Range 0.03 0.04 0.01

[0167] As can be seen from Table 6, the range of the content of each metal element in different parts of the ingot is no greater than 0.3%, indicating good uniformity.

[0168] Furthermore, referring to GB / T 23605-2020, the phase transformation temperatures at the upper and lower ends of the ingot are 988℃ and 990℃, respectively. This shows that the alloy element content at the upper and lower parts of the ingot has little impact on the phase transformation point, which also confirms the uniformity of the ingot composition.

[0169] Example 3

[0170] The method of Example 1 is different except that in step S2, the arc-starting current is increased to 24kA for the second time, the arc-starting voltage remains unchanged, and is maintained for 8 minutes, so that the arc-starting current increased for the second time is 120% of the arc-starting current increased for the first time.

[0171] The content of each metal element at different parts of the bottom of the ingot was sampled and tested, and the results are shown in Table 7.

[0172] Table 7

[0173] Part Al Nb Zr Mo Fe 1 6.27 3.17 2.15 1.16 0.030 2 6.22 3.12 2.12 1.20 0.031 3 6.18 3.08 2.10 1.23 0.034 4 6.22 3.14 2.09 1.20 0.032 5 6.25 3.16 2.16 1.14 0.027 6 6.24 3.18 2.12 1.14 0.026 7 6.26 3.11 2.10 1.19 0.033 8 6.20 3.17 2.09 1.20 0.034 9 6.26 3.20 2.16 1.15 0.027 Range 0.09 0.12 0.07 0.09 0.008

[0174] Example 4

[0175] The method is the same as in Example 1, except that in step S4, the arc ignition current is increased to 20kA and the arc ignition voltage is increased to 35V for the first time, and the arc ignition current and arc ignition voltage are maintained for 6 minutes. The arc ignition current is increased to 22.5kA and the arc ignition voltage is increased to 35V for the second time, and the arc ignition current and arc ignition voltage are maintained for 4 minutes. The arc ignition current is increased to 24kA and the arc ignition voltage is increased to 35V for the third time, and the arc ignition current and arc ignition voltage are maintained for 10 minutes.

[0176] The content of each metal element at different parts of the bottom of the ingot was sampled and tested, and the results are shown in Table 8.

[0177] Table 8

[0178] Part Al Nb Zr Mo Fe 1 6.28 3.21 2.13 1.14 0.031 2 6.22 3.16 2.10 1.18 0.033 3 6.18 3.08 2.08 1.23 0.035 4 6.23 3.15 2.11 1.19 0.033 5 6.27 3.19 2.14 1.13 0.029 6 6.29 3.20 2.15 1.15 0.030 7 6.23 3.17 2.09 1.20 0.034 8 6.20 3.16 2.13 1.22 0.036 9 6.27 3.20 2.15 1.13 0.029 Range 0.11 0.13 0.07 0.10 0.007

[0179] Example 5

[0180] The method of Example 1 is different except that in step S2, the arc-starting current is increased to 25kA for the second time, the arc-starting voltage remains unchanged, and is maintained for 8 minutes, so that the arc-starting current increased for the second time is 125% of the arc-starting current increased for the first time.

[0181] The content of each metal element at different parts of the bottom of the ingot was sampled and tested, and the results are shown in Table 9.

[0182] Table 9

[0183]

[0184]

[0185] Comparative Example 1

[0186] The method is the same as in Example 1, except that the arc-initiating process is as follows:

[0187] S1. The arc ignition current is 3kA and the arc ignition voltage is 28V. Maintain for 7 minutes, then cut off the power for 30 seconds. Then increase the arc ignition current to 20kA and the arc ignition voltage to 36V. Maintain the arc ignition current and arc ignition voltage for 23 minutes. Then perform the first melting as in Example 1 to obtain a first ingot.

[0188] S2. Other conditions are the same as in Example 1, except that the first arc-starting current is 4kA, the first arc-starting voltage is 28V, and it is held for 9 minutes. Then the arc-starting current is increased to 20kA, the arc-starting voltage is increased to 35V, and it is held for 20 minutes. The second melting is carried out under the same conditions as in Example 1.

[0189] S3. Other conditions are the same as in Example 1, except that the first arc-starting current is 4kA, the first arc-starting voltage is 28V, and it is held for 9 minutes. Then, the third melting is carried out under the same conditions as in Example 1.

[0190] The content of each metal element at different parts of the bottom of the ingot was sampled and tested, and the results are shown in Table 10.

[0191] Table 10

[0192]

[0193]

[0194] Comparative Example 2

[0195] The method is the same as in Example 1, except that in step S1, the arc initiation process is as follows: arc initiation current is 3kA, arc initiation voltage is 28V, held for 4min, power off for 30s, and then the second arc initiation is performed. The second arc initiation current is 3kA, the second arc initiation voltage is 28V, and the second holding time is 3min. All other aspects are the same as in Example 1.

[0196] The content of each metal element at different parts of the bottom of the ingot was sampled and tested, and the results are shown in Table 11.

[0197] Table 11

[0198] Part Al Nb Zr Mo Fe 1 6.08 3.18 2.07 1.13 0.028 2 6.22 3.14 2.09 1.19 0.031 3 6.32 3.05 2.14 1.24 0.036 4 6.22 3.13 2.10 1.18 0.033 5 6.10 3.17 2.08 1.14 0.029 6 6.16 3.19 2.10 1.15 0.028 7 6.21 3.14 2.11 1.16 0.031 8 6.21 3.12 2.09 1.16 0.033 9 6.09 3.19 2.06 1.14 0.027 Range 0.24 0.14 0.08 0.11 0.009

[0199] Comparative Example 3

[0200] The method is the same as in Example 1, except that the arc initiation process in step S1 is as follows: the arc initiation current is 3kA, the arc initiation voltage is 28V, the third holding time is 3min, and then step S2 is performed directly. Everything else is the same as in Example 1.

[0201] The content of each metal element in the ingot was sampled and tested in different parts, and the results are shown in Table 12.

[0202] Table 12

[0203] Part Al Nb Zr Mo Fe 1 6.08 3.20 2.08 1.15 0.028 2 6.21 3.13 2.11 1.17 0.033 3 6.32 3.07 2.15 1.24 0.037 4 6.19 3.14 2.10 1.18 0.032 5 6.11 3.19 2.09 1.14 0.027 6 6.12 3.18 2.09 1.15 0.027 7 6.21 3.11 2.12 1.18 0.033 8 6.22 3.12 2.10 1.19 0.032 9 6.10 3.19 2.07 1.14 0.026 Range 0.24 0.13 0.08 0.10 0.011

[0204] As can be seen from the above, the ingots produced by the intermittent arc initiation process in Examples 1-5 provided by the present invention have uniform composition and no segregation. The range of the content of each metal element in different parts of the ingot is no greater than 0.12%, which shows good uniformity.

[0205] Comparative Examples 1-3 do not meet the arc-starting process or conditions of the present invention, resulting in a greater than 0.2% range in the content of each metal element in different parts of the obtained ingot, and poor uniformity.

[0206] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for intermittent arc initiation, characterized in that, The method includes: S1. One-time melting: After welding the auxiliary electrode to the consumable electrode, perform n arc initiation, n holding, and n power off, where n is 2-3, and then perform the (n+1)th arc initiation and (n+1)th holding. S2. Increase the arc ignition current and / or arc ignition voltage; perform this operation m times, where m is 2-3. After each increase in arc ignition current and arc ignition voltage, maintain the current and voltage, and then perform the first melting to obtain one ingot. S3, Secondary Melting: After the primary ingot undergoes the first treatment, the auxiliary electrode is sequentially welded to the two primary ingots, and the process is repeated with the following steps: arc initiation, holding, and power off; n' is 2-3. Then, the process is repeated with the following steps: arc initiation and holding. S4. Increase the arc-starting current and arc-starting voltage and perform this operation m' times, where m' is 3-4. After each increase in arc-starting current and arc-starting voltage, maintain the current and voltage, and then perform a second melting to obtain a secondary ingot. S5. Three-stage melting: After the secondary ingot is processed, the auxiliary electrode is welded to the secondary ingot. Then, the arc is started, held, and de-energized for the n”th time, where n” is 2-3. Then, the arc is started and held for the n”+1th time. S6. Increase the arc ignition current and / or arc ignition voltage; perform this operation m” times, where m” is 3-4. After each increase in arc ignition current and arc ignition voltage, maintain the current and voltage, and then perform a third melting process to obtain three ingots.

2. The method according to claim 1, characterized in that, The conditions for the nth arc initiation include: arc initiation current of 3-4kA and arc initiation voltage of 27-29V; And / or, the holding time for the nth time is 2-3 minutes, and the power-off time for the nth time is 20-40 seconds; And / or, the conditions for the (n+1)th arc initiation and the nth arc initiation each independently include: an arc initiation current of 3-4kA, an arc initiation voltage of 27-29V, and a holding time of 3-5min for the (n+1)th arc initiation.

3. The method according to claim 1, characterized in that, In step S2, the conditions for the first arc initiation current include: arc initiation current of 19-26kA, arc initiation voltage of 33-37V, and holding for 4-6 minutes; And / or, the arc-starting current of the mth time is 105-120% of the current of the (m-1)th time, and the arc-starting voltage of the mth time is 100-110% of the voltage of the (m-1)th time; And / or, the holding time for the m-th arc initiation is 8-15 minutes.

4. The method according to claim 1, characterized in that, The conditions for the n'th arc initiation include: an arc initiation current of 4-5kA and an arc initiation voltage of 27-29V; And / or, the holding time for the n'th time is 2-3 minutes, and the power-off time for the n'th time is 20-40 seconds; And / or, the current of the n'th arc initiation is 120-130% of the current of the nth arc initiation, and the voltage of the n'th arc initiation is 100-105% of the voltage of the nth arc initiation; And / or, the conditions for the (n'+1)th arc initiation include: an arc initiation current of 3-4 kA, an arc initiation voltage of 27-29 V, and a holding time of 3-6 min for the (n'+1)th arc initiation.

5. The method according to claim 1, characterized in that, In step S4, the first and second improvements to the arc initiation conditions each independently include: an arc initiation current of 19-26kA, an arc initiation voltage of 33-38V, and a holding time of 6-8 minutes; And / or, the arc-starting current of the m'th arc is 90-115% of the arc-starting current of the m'-1th arc, and the arc-starting voltage of the m'th arc is 100-105% of the arc-starting voltage of the m'-1th arc; And / or, the holding time for the m'th time is 3-10 min.

6. The method according to claim 1, characterized in that, The conditions for the nth arc initiation include: arc initiation current of 4-5kA and arc initiation voltage of 27-29kA; And / or, the holding time for the nth time is 2-3 minutes, and the power-off time for the nth time is 20-40 seconds.

7. The method according to claim 1, characterized in that, In step S6, the first and second improvements to the arc initiation conditions each independently include: an arc initiation current of 22-31kA, an arc initiation voltage of 33-38V, and a holding time of 6-10 minutes.

8. The method according to claim 1, characterized in that, The arc-starting current of the m”th time is less than the arc-starting current of the m”-1th time, and the arc-starting voltage of the m”th time is greater than or equal to the arc-starting voltage of the m”-1th time. And / or, the arc-starting current of the m”th arc is 90-120% of the current of the m”-1th arc, and the arc-starting voltage of the m”th arc is 100-105% of the voltage of the m”-1th arc; And / or, the holding time for the m”th arc initiation is 4-12 min.

9. An ingot obtained by the method of any one of claims 1-8.

10. The application of the ingot according to claim 9 in titanium alloy smelting.

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