A method for reducing segregation risk of titanium alloy ingot

Abstract

The application discloses a method for reducing segregation risk of titanium alloy ingot, comprising the following steps: firstly, removing raw material and forming anti-overflow groove at the bottom of the remelted ingot before loading the furnace, so as to remove the raw material at the bottom of the ingot and form a ring-shaped groove, thereby preventing titanium liquid from flowing out of the end surface of the ingot during auxiliary electrode welding; then, welding the auxiliary electrode in the furnace, and reducing spatter and welding tumor by controlling welding parameters; finally, opening the furnace to check and clean the spatter and welding tumor. The method mainly reduces the generation of welding tumor, the carrying of raw material and the degree of spatter by machining the anti-overflow groove, removing the raw material at the bottom, controlling the welding parameters of the auxiliary electrode and checking and cleaning after welding, so as to reduce the risk of segregation caused by the uneven composition material falling into the molten pool during the present smelting, and improve the metallurgical problem of ingot segregation in the smelting process of titanium alloy.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of metal ingot metallurgy, in particular to a method for reducing the segregation risk of titanium alloy ingot. BACKGROUND

[0002] In the melting process of titanium alloy ingot, segregation is a common metallurgical problem that can lead to uneven distribution of chemical composition within the ingot, thereby affecting the performance of the material and the quality of the final product. Currently, the main methods to solve the above problems include increasing the pressing density of the electrode block and increasing the depth of the molten pool, but these methods have certain limitations. High density of electrode block helps to reduce the possibility of dropping block during melting process, thereby reducing the risk of segregation. However, this method is limited by the tonnage of the press and the upper limit of the pressing density of the electrode block. When the pressing density reaches a certain level, it becomes very difficult to further improve it, and too high density may cause cracks or other defects in the electrode block, which in turn increases the problems in the melting process. Increasing the depth of the molten pool is another technical means. In theory, a deeper molten pool can provide more mixing opportunities for alloying elements, which helps to reduce the occurrence of segregation. However, increasing the depth of the molten pool also increases the risk of dendritic segregation. This is because the deeper the molten pool, the slower the cooling rate, which may cause the enrichment of alloying elements in the interdendritic region, thereby producing segregation. SUMMARY

[0003] Therefore, the present application provides a method for reducing the segregation risk of titanium alloy ingot, which reduces the generation of welding bumps, the introduction of raw materials and the degree of spatter through the steps of removing raw materials and preventing overflow grooves, welding auxiliary electrodes in the furnace, cleaning and checking, etc., thereby effectively improving the metallurgical problem of ingot segregation in the melting process of titanium alloy.

[0004] The technical solutions adopted by the present application are as follows.

[0005] In one aspect, the present application provides a method for reducing the segregation risk of titanium alloy ingot, characterized in that it comprises:

[0006] Step 1): removing raw materials from the bottom of the ingot to be remelted before loading into the furnace;

[0007] Step 2): forming a ring-shaped groove by removing raw materials from the bottom of the ingot to be remelted;

[0008] Step 3): welding auxiliary electrodes in the furnace after loading the ingot into the furnace, and reducing spatter and welding bumps by controlling the welding parameters;

[0009] Step 4): checking and cleaning the spatter and welding bumps after starting the furnace.

[0010] Further, in the step 1), when the ingot head and bottom are to be remelted, the raw material on the edge of the ingot bottom is completely removed by turning, and the feeding amount is 2-3 mm each time.

[0011] Further, in the step 2), when the ingot bottom is to be remelted, an anti-overflow groove is turned on the ingot bottom to retain the titanium liquid generated during the auxiliary electrode welding, so as to prevent the titanium liquid from dropping on the edge of the ingot and forming a welding tumor, the position of the anti-overflow groove needs to be as close to the auxiliary electrode welding position as possible, and the turning speed of the lathe for processing the anti-overflow groove is 3-5 r / min, and the feeding amount is 0.4-0.6 mm / r.

[0012] Further, the inner ring diameter of the anti-overflow groove is the diameter of the auxiliary electrode to be welded + (20-40) mm, and the difference between the inner and outer ring radii of the anti-overflow groove is (50-85) mm, and the anti-overflow groove to the edge of the ingot is not machined after the raw material on the bottom is removed.

[0013] Further, in the step 3), after the ingot is loaded into the furnace and the vacuum is extracted to meet the process requirements, the auxiliary electrode in the furnace is welded with the remelting electrode, the welding parameters are that the current is 2.0-4.0 KA for arc striking, and then the current is kept at 4.0-7.0 KA for welding, and the total welding time is 5-20 min.

[0014] Further, in the step 4), after the auxiliary electrode is welded and cooled, the furnace is opened to check the welding condition and clean the splashes, and the cooling time after welding is ≥20 min.

[0015] Further, the titanium alloy smelting method applicable to the present application includes but is not limited to vacuum arc remelting and vacuum self-consumption condensation shell smelting which need auxiliary electrode welding.

[0016] Further, the size of the auxiliary electrode is φ200-400 mm.

[0017] On the other hand, the present application also provides a titanium alloy ingot smelted by using the method for reducing the segregation risk of the titanium alloy ingot.

[0018] Further, the size of the ingot smelted is φ440-1080 mm.

[0019] The beneficial effects of the present application are as follows:

[0020] Compared with the traditional production which does not pay enough attention to the machining of the semi-finished ingot and the auxiliary electrode welding, and the method for increasing the pressing density of the electrode block and increasing the depth of the molten pool has certain limitations, the present application provides a more reasonable, feasible and convenient method, which includes turning off the raw material and turning off the anti-overflow groove, welding the auxiliary electrode in the furnace, opening the furnace to clean and check to reduce the generation of the welding tumor, the degree of the raw material and the splashes, so as to improve the metallurgical problem of the segregation of the ingot in the titanium alloy smelting process.BRIEF DESCRIPTION OF DRAWINGS BRIEF DESCRIPTION OF DRAWINGS

[0021] Figure 1 Schematic diagram of the anti-overflow groove machining for the embodiment 1 of the present application.

[0022] Figure 2 Actual physical diagram of the anti-overflow groove machining for the embodiment 2 of the present application.

[0023] Figure 3 Interception effect diagram of the anti-overflow groove on the titanium liquid after the auxiliary electrode welding for the embodiment 1 of the present application.

[0024] Figure 4 Actual physical diagram of the anti-overflow groove machining for the embodiment 2 of the present application.

[0025] Figure 5 Interception effect diagram of the anti-overflow groove on the titanium liquid after the auxiliary electrode welding for the embodiment 2 of the present application. DETAILED DESCRIPTION

[0026] In order to make the purpose, technical scheme and advantages of the present application more clear, the present application will be further described in detail below with specific examples and the accompanying drawings. The specific examples described herein are only used to explain the present application, and the present application is not limited to this.

[0027] The present application provides a method for reducing the segregation risk of titanium alloy ingot, comprising the following steps:

[0028] Step one: when the flat head and flat bottom of the ingot to be remelted is formed, the raw material at the edge of the ingot bottom is completely removed by turning, and the feeding amount is 2-3mm each time.

[0029] Step two: an anti-overflow groove is formed on the bottom of the ingot to be remelted by turning, which is a ring-shaped groove. The purpose is to retain the titanium liquid generated during the auxiliary electrode welding by means of the groove, so as to prevent the molten liquid from dropping on the edge of the ingot and forming a welding tumor. The position of the anti-overflow groove needs to be as close as possible to the auxiliary electrode welding position, and it is avoided to be too close to the edge of the ingot. The inner ring diameter of the anti-overflow groove is the diameter of the auxiliary electrode to be welded+(20-40)mm, the difference between the inner and outer ring radii of the anti-overflow groove is(50-85)mm, and the depth and chamfer of the anti-overflow groove are(8-15)*45°mm. After the raw material at the bottom is removed by turning, the anti-overflow groove is not machined to the edge of the ingot, and the machining drawing of the anti-overflow groove is shown in Figure 1 .

[0030] Step three: after the ingot is loaded into the furnace and the vacuum is extracted to the required value, the auxiliary electrode and the remelting electrode are welded in the furnace, the arc is started at 2.0-4.0KA, and then the welding is carried out at 4.0-7.0KA, and the total welding time is 5-20min.

[0031] Step four: after the auxiliary electrode welding cooling time is greater than or equal to 20min, the furnace is opened to check the welding condition and clean the spatter.

[0032] The present application provides the following specific embodiments:

[0033] Example 1

[0034] Take the example of welding a φ750mm ingot with a φ300mm auxiliary electrode, and smelting a φ820mm finished ingot.

[0035] Step one: Plane the bottom of the φ750mm ingot to be remelted and remove the raw material at the bottom, with an amount of 2-3mm per time.

[0036] Step two: Turn the anti-overflow groove at the bottom of the ingot to be remelted, with an inner ring radius of 160mm, an outer ring radius of 230mm, a difference of 70mm between the inner and outer ring radii, and a depth and chamfer of 12*45°mm. After removing the raw material at the bottom, the anti-overflow groove does not need to be machined to the edge of the ingot, and the physical object after machining is shown in Figure 2 .

[0037] Step three: After the ingot is loaded into the furnace and the vacuum is reached, the auxiliary electrode and the remelted electrode are welded in the furnace, with a welding parameter of an arc starting current of 3.0-4.0KA, followed by a welding current of 5.5-6.5KA, and a total welding time of 14-16min.

[0038] Step four: After the auxiliary electrode is cooled, the welding condition is checked and the spatter is cleaned. The cooling time after welding is 30min, and the anti-overflow groove's interception effect on the molten liquid after the auxiliary electrode is welded is shown in Figure 3 .

[0039] Example 2

[0040] Take the example of welding a φ680mm ingot with a φ280mm auxiliary electrode, and smelting a φ750mm finished ingot.

[0041] Step one: Plane the bottom of the φ680mm ingot to be remelted and remove the raw material at the bottom, with an amount of 2-3mm per time.

[0042] Step two: Turn the anti-overflow groove at the bottom of the ingot to be remelted, with an inner ring radius of 150mm, an outer ring radius of 215mm, a difference of 65mm between the inner and outer ring radii, and a depth and chamfer of 10*45°mm. After removing the raw material at the bottom, the anti-overflow groove does not need to be machined to the edge of the ingot, and the physical object after machining is shown in Figure 4 .

[0043] Step three: After the ingot is loaded into the furnace and the vacuum is reached, the auxiliary electrode and the remelted electrode are welded in the furnace, with a welding parameter of an arc starting current of 2.5-3.0KA, followed by a welding current of 5.0-6.0KA, and a total welding time of 12-14min.

[0044] Step four: after the auxiliary electrode welding cooling, open the furnace to check the welding condition and clean the splashing. The cooling time after welding is 25 min, and the interception effect of the anti-overflow groove on the molten liquid after the auxiliary electrode welding is as shown in Figure 5

[0045] Example 3

[0046] Take the auxiliary electrode diameter φ200mm, the welding φ440mm ingot, and the smelting φ520mm finished ingot as an example.

[0047] Step one: the φ440mm to be remelted ingot is flat bottomed and the bottom raw material is removed, and the feed rate is 2-3mm per time.

[0048] Step two: the anti-overflow groove is turned on the bottom of the to-be-remelted ingot, the inner ring radius of the anti-overflow groove is 110mm, the outer ring radius of the anti-overflow groove is 161mm, the inner and outer ring radius difference of the anti-overflow groove is 51mm, and the anti-overflow groove depth and chamfer is 8*45°mm. After the bottom raw material is removed, the anti-overflow groove to the edge of the ingot is not machined, the cutting speed of the lathe is 3-5r / min, and the feed rate is 0.4-0.6mm / r.

[0049] Step three: after the ingot is loaded into the furnace and the vacuum is reached, the in-furnace auxiliary electrode and the remelted electrode are welded, the starting arc current is 2.0-2.5KA, and then the welding is maintained at 4.0-6.0KA, and the total welding time is 5-8min.

[0050] Step four: after the auxiliary electrode welding cooling, open the furnace to check the welding condition and clean the splashing. The cooling time after welding is 20min.

[0051] Example 4

[0052] Take the auxiliary electrode diameter φ400mm, the welding φ1080mm ingot, and the smelting φ1160mm finished ingot as an example.

[0053] Step one: the φ1080mm to be remelted ingot is flat bottomed and the bottom raw material is removed, and the feed rate is 2-3mm per time.

[0054] Step two: the anti-overflow groove is turned on the bottom of the to-be-remelted ingot, the inner ring radius of the anti-overflow groove is 220mm, the outer ring radius of the anti-overflow groove is 305mm, the inner and outer ring radius difference of the anti-overflow groove is 85mm, and the anti-overflow groove depth and chamfer is 15*45°mm. After the bottom raw material is removed, the anti-overflow groove to the edge of the ingot is not machined, the cutting speed of the lathe is 3-5r / min, and the feed rate is 0.4-0.6mm / r.

[0055] ​Step three: after the ingot is put into the furnace and vacuum is extracted to reach the process requirements, in-furnace auxiliary electrode and remelting electrode welding is performed, the welding parameters are that the current is 3.5-4.0 KA for arc starting, then the current is kept at 5.5-7.0 KA for welding, and the total welding time is 18-20 min.

[0056] Step four: after the auxiliary electrode is welded and cooled, the furnace is opened to check the welding condition and clean the splashes. The cooling time after welding is 40 min.

[0057] It can be understood that the effective combinations of the above different diameter auxiliary electrodes and the smelting ingot types are all within the protection scope of the present application.

[0058] It should be noted that the above-described embodiments are only preferred embodiments of the present application. For ordinary skilled in the art, several modifications, improvements and equivalent replacements can be made to the present application without departing from the principles of the present application, and these modifications, improvements and equivalent replacements are also considered to fall within the protection scope of the claims of the present application.

Claims

1. A method for reducing the risk of segregation in titanium alloy ingots, characterized in that, include: Step 1): Before loading the furnace, remove the raw material from the bottom of the ingot to be remelted; Step 2): Machine an anti-overflow groove at the bottom of the ingot to be remelted to form an annular groove; the inner ring diameter of the anti-overflow groove is the diameter of the auxiliary electrode to be welded + (20~40) mm, and the difference between the inner and outer ring radii of the anti-overflow groove is (50~85) mm. After removing the bottom raw material, the anti-overflow groove to the edge of the ingot is not machined. Step 3): After the ingot is loaded into the furnace, auxiliary electrodes are welded inside the furnace. Welding parameters are controlled to reduce spatter and weld beads. After the ingot is loaded into the furnace and the vacuum is evacuated to meet the process requirements, the auxiliary electrodes and remelting electrodes inside the furnace are welded. The welding parameters are: arc initiation with a current of 2.0~4.0 KA, followed by welding at 4.0~7.0 KA. The total welding time is 5~20 min. Step 4): Open the furnace for inspection and clean up any splashes and molten metal.

2. The method for reducing the risk of segregation in titanium alloy ingots according to claim 1, characterized in that, In step 1), when the top and bottom of the ingot to be remelted are flattened, the raw material at the bottom edge of the ingot is completely removed by machining, with a feed rate of 2-3 mm each time.

3. The method for reducing the risk of segregation in titanium alloy ingots according to claim 1, characterized in that, In step 2), an anti-overflow groove is machined at the bottom of the ingot to be remelted to trap the molten titanium generated during the welding of the auxiliary electrode, preventing the molten titanium from dripping off the edge of the ingot and forming weld beads. The anti-overflow groove should be located as close as possible to the welding position of the auxiliary electrode, avoiding it being too close to the edge of the ingot. The cutting speed of the lathe used to machine the anti-overflow groove is 3~5 r / min, and the feed rate is 0.4~0.6 mm / r.

4. The method for reducing the risk of segregation in titanium alloy ingots according to claim 1, characterized in that, In step 4), after the auxiliary electrode welding has cooled, the furnace is opened to check the welding condition and clean up the spatter. The cooling time after welding is ≥20 min.

5. The method for reducing the risk of segregation in titanium alloy ingots according to claim 1, characterized in that: The auxiliary electrode has a size of φ200~400mm.

6. A titanium alloy ingot smelted using the method for reducing the risk of segregation in titanium alloy ingots according to claim 1.

7. The titanium alloy ingot according to claim 6, wherein the ingot size is φ440~1080mm.

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