A method for arc distance control of titanium alloy ingot production

Abstract

The application discloses a method for preparing titanium alloy ingot by arc distance control, which comprises the following steps: assembling a titanium alloy bottom pad, a crucible bottom pad and a crucible barrel, placing a titanium alloy consumable electrode in the center of the crucible barrel, and preparing before melting; setting an initial arc distance and other parameters and then starting arc; after entering the arc starting period, melting is carried out by arc distance control; after starting arc, the arc distance is manually stretched to 30-50 mm within 2 s, and then the arc distance automatically falls back to the initial arc distance until the whole arc starting process; after entering the normal melting period, the arc distance needs to be adjusted to the range of 15-25 mm, and it is ensured that there are molten drops with the size in the range of 0.01-0.50 mm in every 10 min time period during the melting process; after entering the feeding period, the arc distance needs to be adjusted to the range of 20-30 mm until the feeding is completed and the furnace is cooled out. In the melting process, the arc distance control can meet the requirements of the production of conventional ingots, large-size ingots and multi-element titanium alloy ingots.

Description

Technical Field

[0001] This invention belongs to the field of titanium alloy smelting technology, specifically relating to a method for preparing titanium alloy ingots by controlling the arc distance. Background Technology

[0002] Titanium alloys are widely used in aerospace, aviation, and medical fields due to their excellent comprehensive properties. The compositional uniformity of titanium alloy ingots is one of the most critical aspects of the manufacturing process for various titanium alloy products. In the ingot smelting stage, the final product smelting is the most crucial. In existing technologies, the main parameters controlled during final product smelting include current, voltage, melting rate, vacuum degree, inlet water temperature, and outlet water temperature, while the arc distance is not used as a control parameter. The arc distance is automatically adjusted as a follow-up parameter based on the difference between the actual voltage value and the set value. While the current method can meet the requirements for ingot uniformity, there is still a certain risk to the compositional uniformity of large-sized, multi-element titanium alloy ingots. Summary of the Invention

[0003] The purpose of this invention is to provide a method for preparing titanium alloy ingots by controlling the arc distance. This invention uses arc distance control during the smelting process, which can simultaneously meet the needs of conventional ingot production, large-size, and multi-element titanium alloy ingot production.

[0004] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0005] A method for preparing titanium alloy ingots with controlled arc distance includes the following steps:

[0006] S1. Assemble the titanium alloy base pad, crucible base pad and crucible cylinder, and place the titanium alloy consumable electrode in the crucible cylinder to prepare for melting.

[0007] S2, after setting the initial arc distance and other parameters, initiate the arc;

[0008] The initial arc distance is in the range of 20~30mm, the initial water flow rate is 500-700L / min, the initial current is 6kA, the initial voltage is 26-28V, the arc stabilization is 5-10A, and the arc stabilization period is 5-10s.

[0009] S3, after entering the arc ignition period, melting is carried out by controlling the arc distance. After the arc is ignited by power, the arc distance is manually stretched to 30~50mm within 2s. Then the arc distance automatically falls back to the initial arc distance until the entire arc ignition process is completed.

[0010] S4. After entering the normal melting period, the arc distance needs to be adjusted to the range of 15~25mm, and ensure that there are molten droplets of 0.01~0.50mm in size within every 10min time cycle during the melting process.

[0011] Observe the droplet situation every 10 minutes. If no droplets appear, adjust the arc distance to 15mm. If droplets continue to appear and vary within the range of 0.01-0.5mm, keep the arc distance unchanged. If the droplets are larger than 0.5mm, increase the arc distance to 25mm. The water flow rate is 1100-1300L / min.

[0012] S5, after entering the feeding period, the arc distance needs to be adjusted to the range of 20~30mm until the feeding is completed and the furnace is cooled and removed.

[0013] Preferably, in S1, the diameter of the titanium alloy base pad is φ700~900mm, the thickness is in the range of 10~30mm, the skewness is ≤5mm, and the material of the titanium alloy base pad is the same grade as the titanium alloy consumable electrode.

[0014] Preferably, in S1, the diameter of the titanium alloy consumable electrode is φ640~850mm.

[0015] Preferably, in step S1, the titanium alloy consumable electrode is placed centered inside the crucible body to ensure that the crucible gap deviation at the four symmetrical positions is ≤5mm, and the crucible gap at any position is ≥30mm.

[0016] Preferably, in step S5, the water flow rate is maintained at 1100~1300 L / min.

[0017] The beneficial effects of this invention are as follows: the method of using arc distance control, combined with current control or melting rate control, to melt titanium alloy ingots during the melting process, and using voltage as a driven parameter for matching and adjustment, can not only meet the needs of conventional ingot production, but also meet the requirements of compositional uniformity of large-size, multi-element titanium alloy ingots. Attached Figure Description

[0018] Figure 1 This is a side view of the crucible gap, where 1 is the titanium alloy base pad, 2 is the crucible base pad, 3 is the crucible cylinder, and 4 is the titanium alloy consumable electrode.

[0019] Figure 2 This is a top view of the crucible gap, where the lengths of points a, b, c, and d represent the crucible gap.

[0020] Figure 3 This is a schematic diagram showing the arc distance range at different stages of the entire smelting process. Detailed Implementation

[0021] To make the objectives, technical solutions, and advantages of the present invention clearer, the technical solutions of the present invention will be clearly and completely described below in conjunction with the accompanying drawings and embodiments.

[0022] like Figures 1 to 3As shown, a method for preparing titanium alloy ingots by controlling the arc distance includes the following steps:

[0023] S1. Assemble the titanium alloy base pad 1, crucible base pad 2 and crucible cylinder 3, and place the titanium alloy consumable electrode 4 in the crucible cylinder 3 in a centered position to prepare for melting.

[0024] S101, assemble the titanium alloy base pad 1, the crucible base pad 2 and the crucible cylinder 3, and then place them in the melting station.

[0025] After cleaning, the titanium alloy base pad 1 with a diameter of φ700~900mm, a thickness of 10~30mm, and a deviation of ≤5mm is assembled on the crucible base pad 2. The crucible base pad 2 and the crucible cylinder 3 are then assembled and placed in the melting station.

[0026] The material of the titanium alloy base pad 1 must be of the same grade as the titanium alloy consumable electrode 4.

[0027] S102, the titanium alloy consumable electrode 4 is placed in the crucible body 3 and one end of the auxiliary electrode is connected to the pneumatic chuck of the electric arc furnace.

[0028] The titanium alloy consumable electrode 4 with a diameter of φ640~850mm is placed in the crucible body 3. The position of the crucible gap is adjusted by tooling to ensure that the deviation of the crucible gap (i.e. the lengths of a, b, c, d) at the four symmetrical positions is ≤5mm, and the crucible gap at any position is ≥30mm. Then the auxiliary electrode is connected to the pneumatic chuck of the electric arc furnace.

[0029] S103, the electric arc furnace is sealed and evacuated. The other end of the auxiliary electrode is welded to the titanium alloy consumable electrode. Then, the welding is cleaned, the titanium alloy consumable electrode 4 is repositioned, and the electric arc furnace is sealed and evacuated again in preparation for smelting.

[0030] The electric arc furnace is sealed and evacuated.

[0031] When the vacuum degree of the electric arc furnace is ≤5Pa and the leakage rate is ≤1Pa / min, in the evacuated vacuum consumable arc furnace chamber, the welding current is controlled in the range of 3kA~15kA, the voltage is controlled in the range of 25V~32V, and the arc is stabilized in the range of 5A~15A. The heat of the electric arc furnace is used to melt the lower end face of the auxiliary electrode and the upper end face of the titanium alloy consumable electrode, and the auxiliary electrode and the titanium alloy consumable electrode 4 are welded together to complete the in-furnace welding.

[0032] Then, post-weld cleaning is performed. The main objects to be cleaned are the inner wall of the crucible, the bottom pad, the auxiliary electrode, the weld and weld beads, as well as the spatter. After cleaning, the titanium alloy consumable electrode 4 is repositioned to ensure that the crucible gap deviation at the four symmetrical positions is ≤5mm and the crucible gap at any position is ≥30mm. The electric arc furnace is then sealed and evacuated again. When the vacuum degree is ≤1.33Pa and the leakage rate is ≤1Pa / min, the furnace is ready for melting.

[0033] S2, after setting the initial arc distance and other parameters, initiate the arc.

[0034] Set the initial arc distance to 20-30mm, the initial water flow rate to 500-700L / min, the initial current to 6kA, the initial voltage to 26-28V, the arc stabilization to 5-10A, and the arc stabilization period to 5-10s. After setting the parameters, start the arc.

[0035] S3, after entering the arc ignition period, melting is carried out by controlling the arc distance. After the arc is ignited by power, the arc distance is manually stretched to 30~50mm within 2s. Then the arc distance automatically falls back to the initial arc distance until the entire arc ignition process is completed.

[0036] S4. After entering the normal melting period, the arc distance needs to be adjusted to the range of 15~25mm, and ensure that there are molten droplets of 0.01~0.50mm in size within every 10min time period during the melting process, and the water flow rate is 1100-1300L / min.

[0037] Observe the molten droplet situation every 10 minutes. If no molten droplet appears, adjust the arc distance to 15mm. If molten droplets continue to appear and vary within the range of 0.01-0.5mm, keep the arc distance unchanged. If the molten droplet is larger than 0.5mm, increase the arc distance to 25mm.

[0038] S5, after entering the feeding period, the arc distance needs to be adjusted to the range of 20~30mm, and the water flow rate should be maintained at 1100~1300L / min until the feeding is completed and the furnace is cooled and discharged.

[0039] When the remaining weight of the titanium alloy consumable electrode is 300~350kg, the feeding period begins. After entering the feeding period, the arc distance needs to be adjusted to 20~30mm, and the water flow rate should be maintained at 1100~1300L / min. During the feeding process, the molten droplet situation is not monitored. Before the feeding is completed, the remaining 4 of the titanium alloy consumable electrode must be complete, with a remaining weight ≥25kg. After the feeding is completed, the ingot should be cooled in the crucible for at least 6 hours before being removed from the furnace and demolded.

[0040] The present invention will be further described in detail below with reference to specific embodiments.

[0041] Example 1: Preparation of 720mm TC4 titanium alloy by arc pitch control

[0042] S1. Assemble the TC4 base pad, crucible base pad, and crucible cylinder, and place the TC4 consumable electrode in the crucible cylinder to prepare for melting.

[0043] S101. After cleaning the TC4 alloy base pad with a diameter of φ700mm, a thickness of 10mm, and a deviation of ≤5mm, assemble it on the crucible base pad, then assemble the crucible base pad and the crucible cylinder, and then place it in the melting station.

[0044] SS102, align the φ640mm TC4 consumable electrode in the crucible, adjust the crucible gap position using the tooling to ensure that the crucible gap deviation at the four symmetrical positions is ≤5mm, and the crucible gap at any position is ≥30mm, and then connect the auxiliary electrode to the pneumatic chuck of the electric arc furnace.

[0045] SS103, seal the furnace, evacuate the furnace. When the vacuum degree is ≤5Pa and the leakage rate is ≤1Pa / min, control the welding current in the range of 3kA~12kA, the voltage in the range of 25V~30V, and the arc stabilization in the range of 5A~15A to complete the in-furnace welding. Then perform post-weld cleaning, mainly cleaning the inner wall of the crucible, the bottom pad, the auxiliary electrode, the weld and weld beads, and the spatter. After cleaning, re-align the TC4 consumable electrode to ensure that the crucible gap deviation at the four symmetrical positions is ≤5mm, and the crucible gap at any position is ≥30mm. Seal the furnace again, evacuate the furnace, and when the vacuum degree is ≤1.33Pa and the leakage rate is ≤1Pa / min, prepare for melting.

[0046] S2, set the initial arc distance to 20mm, the initial water flow rate to 500L / min, the initial current to 6kA, the initial voltage to 26V, the arc stabilization to 5A, and the arc stabilization period to 5s, and start the arc.

[0047] S3, melting is carried out by arc distance control. After the arc is ignited by power, the arc distance is manually stretched to 30mm within 2 seconds. Then, the arc distance is automatically adjusted by the equipment and automatically dropped back to 20mm. Molten droplets continue to appear and vary within the range of 0.01-0.5mm. The arc distance remains unchanged until the entire arc ignition process is over.

[0048] S4. After entering the normal melting period, the arc distance should be controlled within the range of 20mm ± 5mm, ensuring that there are molten droplets of 0.01~0.50mm in size within each 10-minute time cycle during the melting process. Observe the molten droplet situation every 10 minutes. If no molten droplets appear, adjust the arc distance to 15mm. If molten droplets continue to appear and vary within the range of 0.01-0.5mm, keep the arc distance unchanged. If the molten droplets are larger than 0.5mm, increase the arc distance to 25mm. The water flow rate should be maintained at 1200±100L / min.

[0049] When the remaining weight of the S5 and TC4 consumable electrode reaches 300kg, the feeding period begins. The arc distance is adjusted to within the range of 25mm±5mm, and the water flow rate is maintained at 1200±100L / min. At this time, the molten droplet state is no longer monitored, and the arc distance is used for control until the feeding is completed. It should be noted that the remaining TC4 consumable electrode must be a complete residue with a remaining weight ≥25kg. Finally, the ingot is cooled in the crucible for at least 6 hours before being removed from the furnace and demolded.

[0050] Chemical composition samples were taken from the head, middle and tail of the ingot for testing. It can be seen that the chemical composition is well uniform, and the range of Al and V elements is less than 3000 ppm (as shown in Table 1).

[0051] Table 1 Chemical composition (wt.%) of TC4 for φ720 specification prepared by arc pitch control

[0052]

[0053] Example 2: Preparation of φ920 TA15 alloy by arc pitch control

[0054] S1. Assemble the TA15 base pad, crucible base pad, and crucible cylinder, and place the TA15 consumable electrode in the crucible cylinder to prepare for melting.

[0055] S101. After cleaning the TA15 alloy base pad with a diameter of φ900mm, a thickness of 20mm, and a deviation of ≤5mm, assemble it on the crucible base pad, then assemble the crucible base pad and the crucible cylinder, and then place it in the melting station.

[0056] S102, align the 850mm TA15 consumable electrode in the crucible, adjust the crucible gap position using the tooling to ensure that the crucible gap deviation at the four symmetrical positions is ≤5mm, and the crucible gap at any position is ≥30mm, and then connect the auxiliary electrode to the pneumatic chuck of the electric arc furnace.

[0057] S103, seal the furnace and evacuate. When the vacuum degree is ≤5Pa and the leakage rate is ≤1Pa / min, control the welding current in the range of 4kA~15kA, the voltage in the range of 25V~32V, and the arc stabilization in the range of 5A~15A to complete the furnace welding. Then perform post-weld cleaning, mainly cleaning the inner wall of the crucible, the bottom pad, the auxiliary electrode, the weld and weld beads, and the spatter. After cleaning, re-align the TA15 consumable electrode to ensure that the crucible gap deviation at the four symmetrical positions is ≤5mm, and the crucible gap at any position is ≥30mm. Seal the furnace again and evacuate. When the vacuum degree is ≤1.33Pa and the leakage rate is ≤1Pa / min, prepare for melting.

[0058] S2, set the initial arc distance to 25mm, the initial water flow rate to 600L / min, the initial current to 6kA, the initial voltage to 28V, the arc stabilization to 8A, and the arc stabilization period to 10s, and use these parameters to initiate the arc.

[0059] S3, melting is carried out by arc pitch control. After the arc is ignited by power, the arc pitch is manually stretched to 40mm within 2 seconds. Then, the arc pitch is automatically adjusted by the equipment and automatically dropped back to 25mm. Molten droplets continue to appear and vary within the range of 0.01-0.5mm. The arc pitch remains unchanged until the entire arc ignition process is over.

[0060] S4. After entering the normal melting period, the arc distance should be controlled within the range of 20mm ± 5mm, ensuring that there are molten droplets of 0.01~0.50mm in size within each 10-minute time cycle during the melting process. Observe the molten droplet situation every 10 minutes. If no molten droplets appear, adjust the arc distance to 15mm. If molten droplets continue to appear and vary within the range of 0.01-0.5mm, keep the arc distance unchanged. If the molten droplets are larger than 0.5mm, increase the arc distance to 25mm. The water flow rate should be maintained at 1200±100L / min.

[0061] When the remaining weight of the S5 TA15 consumable electrode is 350kg, the feeding period begins. The arc distance is adjusted to within the range of 25mm±5mm, and the water flow rate is maintained at 1200±100L / min. At this time, the molten droplet state is no longer monitored. Arc distance control is used until the feeding is completed. It should be noted that the remaining TA15 consumable electrode must be a complete residue with a remaining weight ≥60kg. Finally, the ingot is cooled in the crucible for at least 6 hours before being removed from the furnace and demolded.

[0062] Chemical composition samples were taken from the head, middle and tail of the ingot for testing. It can be seen that the chemical composition is well uniform, and the range of Al, Mo, V and Zr elements is less than 3000 ppm (as shown in Table 2).

[0063] Table 2 Chemical composition (wt.%) of TA15 alloy for φ920 specification prepared by arc pitch control

[0064]

[0065] Example 3: Preparation of φ920 Ti80 alloy by arc pitch control

[0066] S1. Assemble the Ti80 base pad, crucible base pad, and crucible cylinder. Place the Ti80 consumable electrode in the crucible cylinder 3 to prepare for melting.

[0067] S101. After cleaning the Ti80 alloy base pad with a diameter of φ700mm, a thickness of 30mm, and a deviation of ≤5mm, it is assembled on the crucible base pad, and the crucible base pad and crucible cylinder are assembled and then placed in the melting station.

[0068] S102, align the φ640mm Ti80 consumable electrode in the crucible, adjust the crucible gap position using tooling to ensure that the crucible gap deviation at the four symmetrical positions is ≤5mm, and the crucible gap at any position is ≥30mm, and then connect the auxiliary electrode to the pneumatic chuck of the electric arc furnace.

[0069] S103, seal the furnace and evacuate. When the vacuum degree is ≤5Pa and the leakage rate is ≤1Pa / min, control the welding current in the range of 4kA~15kA, the voltage in the range of 25V~32V, and the arc stabilization in the range of 5A~15A to complete the furnace welding. Then perform post-weld cleaning, mainly cleaning the inner wall of the crucible, the bottom pad, the auxiliary electrode, the weld and weld beads, and the spatter. After cleaning, re-align the Ti80 consumable electrode to ensure that the crucible gap deviation at the four symmetrical positions is ≤5mm, and the crucible gap at any position is ≥30mm. Seal the furnace again and evacuate. When the vacuum degree is ≤1.33Pa and the leakage rate is ≤1Pa / min, prepare for melting.

[0070] S2, set the initial arc distance to 30mm, the initial water flow rate to 700L / min, the initial current to 6kA, the initial voltage to 26V, the arc stabilization to 10A, and the arc stabilization period to 10s, and start the arc.

[0071] S3, melting is carried out by arc pitch control. After the arc is ignited by power, the arc pitch is manually stretched to 50mm within 2 seconds. Then, the arc pitch is automatically adjusted by the equipment and automatically dropped back to 30mm. Molten droplets continue to appear and vary within the range of 0.01-0.5mm. The arc pitch remains unchanged until the entire arc ignition process is over.

[0072] S4. After entering the normal melting period, the arc distance should be controlled within the range of 20mm ± 5mm, ensuring that there are molten droplets of 0.01~0.50mm in size within each 10-minute time cycle during the melting process. Observe the molten droplet situation every 10 minutes. If no molten droplets appear, adjust the arc distance to 15mm. If molten droplets continue to appear and vary within the range of 0.01-0.5mm, keep the arc distance unchanged. If the molten droplets are larger than 0.5mm, increase the arc distance to 25mm. The water flow rate is 1200±100L / min.

[0073] When the remaining weight of the Ti80 consumable electrode reaches 350kg, the feeding period begins. The arc distance is adjusted to within the range of 25mm±5mm, and the water flow rate is maintained at 1200±100L / min. At this time, the molten droplet state is no longer monitored, and the arc distance is used for control until the feeding is completed. It should be noted that the remaining Ti80 consumable electrode must be a complete residue with a remaining weight ≥60kg. Finally, the ingot is cooled in the crucible for at least 6 hours before being removed from the furnace and demolded.

[0074] Chemical composition samples were taken from the head, middle and tail of the ingot for testing. It can be seen that the chemical composition is well uniform, and the range of Al, Zr, Mo and Nb elements is less than 3000 ppm (as shown in Table 3).

[0075] Table 3 Chemical composition (wt.%) of Ti80 alloy with φ920 specification prepared by arc pitch control

[0076]

Claims

1. A method for preparing titanium alloy ingots by controlling the arc distance, characterized in that, Includes the following steps: S1. Assemble the titanium alloy base pad, crucible base pad and crucible cylinder, and place the titanium alloy consumable electrode in the crucible cylinder to prepare for melting. S2, after setting the initial arc distance and other parameters, initiate the arc; The initial arc distance is in the range of 20~30mm, the initial water flow rate is 500-700L / min, the initial current is 6kA, the initial voltage is 26-28V, the arc stabilization is 5-10A, and the arc stabilization period is 5-10s. S3, after entering the arc ignition period, melting is carried out by controlling the arc distance. After the arc is ignited by power, the arc distance is manually stretched to 30~50mm within 2s. Then the arc distance automatically falls back to the initial arc distance until the entire arc ignition process is completed. S4. After entering the normal melting period, the arc distance needs to be adjusted to the range of 15~25mm, and ensure that there are molten droplets of 0.01~0.50mm in size within every 10min time cycle during the melting process. Observe the droplet situation every 10 minutes. If no droplets appear, adjust the arc distance to 15mm. If droplets continue to appear and vary within the range of 0.01-0.5mm, keep the arc distance unchanged. If the droplets are larger than 0.5mm, increase the arc distance to 25mm. The water flow rate is 1100-1300L / min. S5, after entering the feeding period, the arc distance needs to be adjusted to the range of 20~30mm until the feeding is completed and the furnace is cooled and removed.

2. The method for preparing titanium alloy ingots by controlling the arc distance according to claim 1, characterized in that, In S1, the diameter of the titanium alloy base pad is φ700~900mm, the thickness is in the range of 10~30mm, the skewness is ≤5mm, and the material of the titanium alloy base pad is the same grade as the titanium alloy consumable electrode.

3. The method for preparing titanium alloy ingots by controlling the arc distance according to claim 1, characterized in that, In S1, the diameter of the titanium alloy consumable electrode is φ640~850mm.

4. The method for preparing titanium alloy ingots by controlling the arc distance according to claim 1, characterized in that, In step S1, the titanium alloy consumable electrode is placed in the crucible body to ensure that the crucible gap deviation at the four symmetrical positions is ≤5mm, and the crucible gap at any position is ≥30mm.

5. The method for preparing titanium alloy ingots by controlling the arc distance according to claim 1, characterized in that, In step S5, the water flow rate is maintained at 1100~1300 L / min.

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