A method for recovering titanium alloy ingot skin scraps in the whole process

Abstract

The application relates to the technical field of titanium material processing, and discloses a method for recovering titanium alloy ingot skin scraps in a whole process, which comprises the following four steps: step one: titanium alloy ingot skin scraps of the same brand and standard are recovered through a lathe, and the ingot skin scraps are crushed and magnetically separated through a special crusher and a magnetic separation device; step two: the ingot skin scraps after crushing and magnetic separation are calculated for batching, the material obtained through batching is equally divided into two parts, and the two parts are mixed with titanium sponge and intermediate alloy and then pressed into electrode blocks; step three: the electrode blocks are spliced according to a group splicing sequence, and then welded into consumable electrodes in a non-tungsten electrode argon gas protection plasma arc welding mode; and step four: the consumable electrodes are subjected to three times of melting in a vacuum consumable arc furnace to obtain titanium alloy finished ingots. The cost of recovering the ingot skin scraps through the above four steps is low, the efficiency is high, the titanium alloy ingots obtained are reliable in quality, and the component distribution is uniform.

Description

Technical Field

[0001] This invention relates to the field of titanium material processing technology, and in particular to a method for the complete process of recycling scrap from titanium alloy ingots. Background Technology

[0002] Titanium alloys are important structural metals, characterized by their light weight, high strength, corrosion resistance, and heat resistance, and are widely used in aerospace, shipbuilding, weaponry, biomedicine, and petrochemical industries. However, due to the high cost of raw materials and production, their application in general commercial and civilian sectors is limited. Therefore, titanium scrap recycling has become a key technical issue of concern in the titanium alloy industry in recent years, and is also an important way to further expand the titanium alloy application market.

[0003] Under current technology, the main types of recycled titanium and titanium alloy materials are scrap blocks, scrap heads, risers, and slats. These are initially melted by repeatedly welding and assembling blocks of different sizes in a VAR (vacuum arc remelting) or EB (electron beam cold hearth) furnace, followed by several more remelting processes in a VAR furnace to obtain titanium alloy ingots. Examples include Chinese patent application CN201610500892, which discloses "A melting and recycling method for converting titanium alloy scrap into dissimilar grades of titanium alloy," and Chinese patent application CN202011183248, which discloses "A method for recovering remelted titanium or titanium alloy scrap using a vacuum arc remelting furnace." However, this method limits the types of recycled materials to blocky materials and cannot directly recover shavings from ingot peeling. Furthermore, it suffers from problems such as the cumbersome process of processing the blocks into fixed-length materials, the high risk of introducing high-melting-point W inclusions during the welding process, and the difficulty in precisely controlling the composition of the ingot due to Al burning during molten metal formation. Summary of the Invention

[0004] To address at least one of the problems existing in the above-mentioned background technology, the present invention provides a method for the full-process recycling of titanium alloy ingot scrap.

[0005] This invention provides a method for the full-process recycling of titanium alloy ingot scrap, comprising the following four steps:

[0006] Step 1: Collect titanium alloy ingot scraps of the same grade and standard using a lathe, and then crush and magnetically separate the ingot scraps using a special crusher and magnetic separator for scrap processing.

[0007] Step 2: Calculate the batching of the crushed and magnetically separated ingot scraps, divide the calculated material into two equal parts, mix both parts evenly with sponge titanium and intermediate alloy, and then press them into electrode blocks.

[0008] Step 3: After the electrode blocks are assembled in the assembly sequence, they are welded into consumable electrodes using plasma arc welding with non-tungsten inert gas protection.

[0009] Step 4: The consumable electrode is melted three times in a vacuum consumable arc furnace to obtain a finished titanium alloy ingot.

[0010] Furthermore, in the above-mentioned method for recycling titanium alloy ingot scraps in the entire process, the scraps from titanium alloy ingots of the same grade and standard recycled by lathe in step one have a width of 5mm to 10mm, a thickness of 0mm to 1mm, and a length of 5mm to 20mm.

[0011] Furthermore, in the above-mentioned method for the full-process recycling of titanium alloy ingot scrap, the proportion of scrap added in step two is 20% to 40%, and the calculation of the proportion of crushed and magnetically separated ingot scrap is calculated using the following formula:

[0012]

[0013] Where A represents the contribution of a certain element in the scrap to the ingot, in kg; A1 to An represent the content of a certain element in different batches of scrap, in wt%; M1 to Mn represent the weight of different batches of scrap, in kg; X represents the amount of ingot fed, in kg; and N represents the proportion of scrap added, ranging from 20% to 40%.

[0014] Furthermore, in the above-mentioned method for recycling titanium alloy ingot scraps in the entire process, the method of pressing the two parts into electrode blocks after uniformly mixing with sponge titanium and intermediate alloy in step two involves two feedings, one pressing, and bidirectional pressing.

[0015] Furthermore, in the above-mentioned method for recycling titanium alloy ingot scraps in a complete process, the two feedings, one pressing, and bidirectional pressing involve mixing the first part of the two parts in a mixer for 60 to 80 seconds and then adding it to the hydraulic press mold cavity for pressing in one step. The pressing is completed by the hydraulic press slider applying pressure once. After the first pressing is completed, the second part of the two parts is mixed in a mixer for 60 to 80 seconds and then added to the hydraulic press mold cavity, where bidirectional pressing is achieved through the action of a floating cylinder.

[0016] Furthermore, in the above-mentioned method for recycling titanium alloy ingot scraping in a complete process, the pressing pressure of a single pressing is 1MPa to 3MPa, and the holding time is 1s to 5s; the pressing pressure of a bidirectional pressing is 25MPa to 30MPa, and the holding time is 5s to 10s.

[0017] Furthermore, in the above-mentioned method for recycling titanium alloy ingot scraps throughout the entire process, a vacuum plasma welding box is used for welding the consumable electrode using a non-tungsten inert gas (TIG) protected plasma arc welding method.

[0018] Furthermore, in the above-mentioned method for recycling titanium alloy ingot scraps in a complete process, the vacuum plasma welding box is evacuated for ≥1.0 hours before welding. When the pre-vacuum of the furnace chamber is ≤1.0Pa and the leakage rate is ≤0.5Pa / min, argon is introduced and the argon pressure is ≥8000Pa.

[0019] Furthermore, in the above-mentioned method for recycling titanium alloy ingot scraps throughout the entire process, in step four, the gap between the consumable electrode and the crystallizer in the first melting of the three melting processes is between 35mm and 65mm.

[0020] Furthermore, in the above-mentioned method for recycling titanium alloy ingot scraps in the whole process, in step four, when the first melting of the three melting processes reaches 1000kg±100kg, the process transitions from the arc initiation period to the normal melting period, and the melting current is reduced by 1kA and the melting voltage is reduced by 1V.

[0021] The beneficial effects of this invention are as follows: The method for recycling titanium alloy ingot scrap through a complete process, using a two-stage feeding, one-stage pressing, and bidirectional pressing approach, improves the uniformity of electrode composition while solving the problem of electrode cracking caused by excessive titanium scrap addition. This improves ingot composition uniformity and reduces the risk of metallurgical defects caused by slag shedding during melting. Extending the evacuation time and tightening the pre-vacuum conditions prevents oxidation of the weld joints caused by slag, thus avoiding excessive oxygen levels in the ingot. Controlling the gap between the consumable electrode and the crystallizer during the first melting stage ensures the molten pool reaches the edge while enhancing venting during melting, preventing excessive oxygen levels in the ingot. Reducing the melting current and voltage during the arc-starting phase before entering the normal melting phase avoids slag shedding and splashing during melting caused by the addition of slag, thus reducing the risk of metallurgical defects caused by slag shedding. Simultaneously, it reduces the risk of foreign matter and high-density inclusions, effectively controlling the increase of impurity elements. The resulting titanium alloy ingot is of more reliable quality and has a more uniform composition distribution. Attached Figure Description

[0022] To more clearly illustrate the technical solutions in the embodiments of the present invention or the conventional technology, the drawings used in the description of the embodiments or the conventional technology will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0023] Figure 1 This is a schematic flowchart of a method for recycling titanium alloy ingot scraps in an embodiment of the present invention. Detailed Implementation

[0024] To make the above-mentioned objects, features, and advantages of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. Many specific details are set forth in the following description to provide a thorough understanding of the present invention. However, the present invention can be practiced in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0025] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0026] Figure 1 This is a schematic flowchart of a method for recycling titanium alloy ingot scraps in an embodiment of the present invention.

[0027] This invention provides a method for the complete recycling of titanium alloy ingot scrap, combined with... Figure 1 It includes four steps, S101 to S104:

[0028] S101: The same grade and standard titanium alloy ingot scrap is recovered by lathe. The ingot scrap is then crushed and magnetically separated by a special crusher and magnetic separator for scrap processing.

[0029] Specifically, in this embodiment of the application, the size of the ingot scraps from titanium alloy ingots of the same grade and standard recovered by lathe is 5mm to 10mm wide, 0mm to 1mm thick, and 5mm to 20mm long.

[0030] S102: The scrap from the crushed and magnetically separated ingots is calculated for batching. The calculated material is divided into two parts. Both parts are mixed evenly with sponge titanium and intermediate alloy and then pressed into electrode blocks.

[0031] Specifically, in this embodiment, in S102, the proportion of peeling shavings added is 20% to 40%, and the calculation of the proportion of peeling shavings from crushed and magnetically separated ingots is calculated using the following formula:

[0032]

[0033] Where A represents the contribution of a certain element in the scrap to the ingot, such as Al, V, Fe, Si, C, N, O, etc., in kg; A1 to An represent the content of a certain element in different batches of scrap in wt%; M1 to Mn represent the weight of scrap in different batches in kg; X represents the amount of ingot material fed in kg; and N represents the proportion of scrap added, ranging from 20% to 40%.

[0034] In S102, the method of pressing two parts into electrode blocks after uniformly mixing with sponge titanium and intermediate alloy is two-time feeding, one-time pressing and bidirectional pressing.

[0035] In this embodiment, the two-feed, one-press, and bidirectional pressing method involves mixing the first portion of the material in a mixer for 60 to 80 seconds before adding it to the hydraulic press cavity for one-press pressing, where the hydraulic press slide applies pressure in a single pass. After the first pressing, the second portion of the material is mixed in a mixer for 60 to 80 seconds before being added to the hydraulic press cavity, where bidirectional pressing is achieved through the action of a floating cylinder. The pressing pressure for the one-press is 1 MPa to 3 MPa, with a holding time of 1 to 5 seconds. The pressing pressure for the bidirectional pressing is 25 MPa to 30 MPa, with a holding time of 5 to 10 seconds.

[0036] It should be understood that this application improves the uniformity of electrode block composition by using two feedings, one pressing and bidirectional pressing, while solving the problem of electrode block cracking caused by large titanium shavings. This is beneficial to improving the uniformity of ingot composition and reducing the risk of metallurgical defects caused by melting and spalling.

[0037] S103: After the electrode blocks are assembled in the assembly sequence, they are welded into consumable electrodes using plasma arc welding with non-tungsten inert gas protection.

[0038] Specifically, in this embodiment, in S103, the vacuum plasma welding box is evacuated for ≥1.0 hour before welding. When the pre-vacuum of the furnace chamber is ≤1.0 Pa and the leakage rate is ≤0.5 Pa / min, argon is introduced, and the argon pressure is ≥8000 Pa. It should be understood that this application prevents the oxidation of the shavings weld joints from causing excessive oxygen in the ingot due to prolonged evacuation time and stricter pre-vacuum conditions.

[0039] S104: The consumable electrode is melted three times in a vacuum consumable arc furnace to obtain a finished titanium alloy ingot.

[0040] Specifically, in this embodiment, in S104, the gap between the consumable electrode and the crystallizer in the first melting of the three melting processes is between 35mm and 65mm. By controlling the gap between the consumable electrode and the crystallizer in the first melting process, the edge-to-edge effect of the molten pool is ensured, while the venting in the molten pool is enhanced, thus preventing the oxygen content in the ingot from exceeding the standard.

[0041] In step S104, during the first of the three melting processes, when the melt volume reaches 1000 kg ± 100 kg, the process transitions from the arc-starting phase to the normal melting phase. The melting current is reduced by 1 kA and the melting voltage by 1 V. This reduction in melting current and voltage during the transition from the arc-starting phase to the normal melting phase prevents sharding and splashing during melting caused by the addition of shavings, thus reducing the risk of metallurgical defects caused by sharding. It also reduces the risk of introducing foreign matter and high-density inclusions, effectively controlling the increase of impurity elements.

[0042] Specifically, the titanium alloy ingots obtained through the four steps S101 to S104 of this application have more reliable quality, more uniform composition distribution, and composition that meets and exceeds the national standard GB / T 3620.1 "Titanium and Titanium Alloys - Grades and Chemical Composition". The process of this invention has high controllability and is easily automated.

[0043] The following describes a method for the complete recycling of titanium alloy ingot scraping from this application, using two embodiments:

[0044] Example 1:

[0045] This embodiment involves the preparation of recycled TC4 ingot scrap. Method for casting 5060kg TC4 ingots:

[0046] Step 1: Recover TC4 ingot scrap using a lathe. The recovered ingot scrap is then crushed and magnetically separated using a special crusher and magnetic separator for scrap processing. The resulting ingot scrap has a width of 5mm to 10mm, a thickness of 0mm to 1mm, and a length of 5mm to 20mm.

[0047] Step 2: The proportion of peeling debris added is 30%, and the contribution values ​​of each element in the ingot are shown in Table 1.

[0048] Table 1. Contribution of 30% of peeling debris to various elements in the ingot.

[0049]

[0050] Based on the mass percentage of each element in the TC4 grade, the required amounts of peeling shavings, sponge titanium, and intermediate alloy for each electrode block were calculated. The peeling shavings, sponge titanium, and intermediate alloy required for a single electrode block were divided into two portions. The first portion was mixed in a mixer for 60 seconds and then added to the hydraulic press cavity for single-stage pressing (1 MPa pressure, 1 second holding time). The second portion was then mixed in a mixer for 60 seconds and added to the hydraulic press cavity. A floating cylinder was used for bidirectional pressing at 26.5 MPa pressure for 5 seconds, resulting in electrode blocks with high density and good surface quality.

[0051] Step 3: After the electrode blocks are spliced, plasma arc welding is performed with argon protection. Before welding, the furnace is evacuated for 1.2 hours and leaks are detected when the furnace is pre-vacuumed to 0.5Pa. The leakage rate is 0.25Pa / min. Argon is then filled at a pressure of 8500Pa. After welding, the weld points are silver-gray, the weld is full, and the welding quality is reliable.

[0052] Step 4: In the first of the three melting processes, the gap between the consumable electrode and the crystallizer is 43.5 mm. The current and voltage parameters during the transition stage are shown in Table 2.

[0053] Table 2 Process parameters from the arc initiation stage to the normal melting stage

[0054] weight (kg) Current kA Voltage V 900 10 to 20 30 to 40 1100 9 to 19 29 to 39

[0055] One piece was obtained after three VAR melting processes. 5060kg TC4 finished ingot.

[0056] The TC4 ingot obtained in step four is peeled, and samples are taken from the head, middle and tail of the ingot for testing. The riser of the ingot is then sawn off.

[0057] The final ingot obtained had a composition that met and exceeded the national standard for TC4 scrap recycling. Its composition is shown in Table 3.

[0058] Table 3 Chemical composition (wt%) of TC4 grade scrap recovered ingots

[0059]

[0060] Example 2:

[0061] This embodiment involves the preparation of recycled TC4 ingot scrap. Method for casting 5060kg TA15 ingots:

[0062] Step 1: Recover TC4 ingot scrap using a lathe. The recovered ingot scrap is then crushed and magnetically separated using a special crusher and magnetic separator for scrap processing. The resulting ingot scrap has a width of 5mm to 10mm, a thickness of 0mm to 1mm, and a length of 5mm to 20mm.

[0063] Step 2: The proportion of peeling debris added is 40%, and the contribution values ​​of each element in the ingot are shown in Table 4.

[0064] Table 4. Contribution of 40% of peeling debris to various elements in the ingot.

[0065]

[0066] Based on the mass percentage of each element in the TA15 grade, the required amounts of peeling shavings, sponge titanium, and master alloy for each electrode block were calculated. The peeling shavings, sponge titanium, and master alloy required for a single electrode block were divided into two portions. The first portion was mixed in a mixer for 60 seconds and then added to the hydraulic press cavity for single-stage pressing (1 MPa pressure, 1 second holding time). The second portion was then mixed in a mixer for 60 seconds and added to the hydraulic press cavity, where a floating cylinder was used for bidirectional pressing at 26.5 MPa pressure for 5 seconds. This resulted in electrode blocks with high density and good surface quality.

[0067] Step 3: After the electrode blocks are spliced, plasma arc welding is performed with argon protection. Before welding, the furnace is evacuated for 1.2 hours. When the furnace is pre-vacuumed to 0.60Pa, leak detection is performed. The leakage rate is 0.27Pa / min. Argon is then filled at an argon pressure of 8500Pa. After welding, the weld points are silver-gray, the weld is full, and the welding quality is reliable.

[0068] Step 4: In the first of the three melting processes, the gap between the consumable electrode and the crystallizer is 43.5 mm. The current and voltage parameters for the transition stage are as follows:

[0069] Table 5 Process parameters from the arc initiation stage to the normal melting stage

[0070]

[0071]

[0072] One piece was obtained after three VAR melting processes. 5060kg TA15 finished ingot.

[0073] The TA15 ingot obtained in step four is peeled, and samples are taken from the head, middle and tail of the ingot for testing. The risers are then sawn off.

[0074] The final obtained TA15 scrap recovery ingot composition is qualified and superior to the national standard, as shown in Table 6:

[0075] Table 6 Chemical composition (wt%) of TA15 grade scrap recovered ingots

[0076]

[0077] The titanium alloy ingots obtained through Examples 1 and 2 described above have more reliable quality, more uniform composition distribution, and their composition meets and exceeds the national standard GB / T 3620.1 "Titanium and Titanium Alloys - Grades and Chemical Composition". The process of this invention has high controllability and is easily automated.

[0078] Those skilled in the art will understand that although some embodiments described herein include certain features included in other embodiments but not others, combinations of features from different embodiments are meant to be within the scope of the invention and form different embodiments.

[0079] Those skilled in the art will understand that the descriptions of the various embodiments have different focuses, and for parts not described in detail in a certain embodiment, reference can be made to the relevant descriptions of other embodiments.

[0080] The above are merely specific embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any person skilled in the art can easily conceive of various equivalent modifications or substitutions within the technical scope disclosed in the present invention, and these modifications or substitutions should all be covered within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A method for the complete recycling of titanium alloy ingot scrap, characterized in that, It includes the following four steps: Step 1: Collect titanium alloy ingot scraps of the same grade and standard using a lathe, and then crush and magnetically separate the ingot scraps using a special crusher and magnetic separator for scrap processing. Step 2: Calculate the batching of the crushed and magnetically separated ingot scraps, divide the calculated material into two equal parts, mix both parts evenly with sponge titanium and intermediate alloy, and then press them into electrode blocks. The specific method for pressing electrode blocks by uniformly mixing the two portions with sponge titanium and intermediate alloy involves two feedings, one pressing, and bidirectional pressing. The two feedings, one pressing, and bidirectional pressing are as follows: the first portion is mixed in a mixer for 60 to 80 seconds and then added to the hydraulic press mold cavity, where it is pressed in one pressing. The hydraulic press slide applies pressure once to complete the pressing. After the first pressing, the second portion is mixed in a mixer for 60 to 80 seconds and then added to the hydraulic press mold cavity, where bidirectional pressing is achieved through the action of a floating cylinder. The single compression pressure is 1MPa to 3MPa, and the holding time is 1s to 5s; the bidirectional compression pressure is 25MPa to 30MPa, and the holding time is 5s to 10s. Step 3: After the electrode blocks are assembled in the assembly sequence, they are welded into consumable electrodes using plasma arc welding with non-tungsten inert gas protection. Step 4: The consumable electrode is melted three times in a vacuum consumable arc furnace to obtain a finished titanium alloy ingot.

2. The method for recycling titanium alloy ingot scraps throughout the entire process according to claim 1, characterized in that, In step one, the scrap from titanium alloy ingots of the same grade and standard, which is recovered by lathe, has a width of 5mm to 10mm, a thickness of 0mm to 1mm, and a length of 5mm to 20mm.

3. The method for recycling titanium alloy ingot scraps throughout the entire process according to claim 1, characterized in that, In step two, the proportion of peeling debris added is 20% to 40%. The proportion of peeling debris from crushed and magnetically separated ingots is calculated using the following formula: Where A represents the contribution of a certain element in the scrap to the ingot, in kg; A1 to An represent the content of a certain element in different batches of scrap, in wt%; M1 to Mn represent the weight of different batches of scrap, in kg; X represents the amount of ingot material fed, in kg; and N represents the proportion of scrap added, ranging from 20% to 40%.

4. The method for recycling titanium alloy ingot scraps throughout the entire process according to claim 1, characterized in that, The process of welding a consumable electrode using a non-tungsten inert gas (TIG) protected plasma arc welding method employs a vacuum plasma welding box.

5. The method for recycling titanium alloy ingot scraps throughout the entire process according to claim 4, characterized in that, Before welding, the vacuum plasma welding box is evacuated for ≥1.0 hours. When the pre-vacuum of the furnace chamber is ≤1.0Pa and the leakage rate is ≤0.5Pa / min, argon is purged and the argon pressure is ≥8000Pa.

6. The method for recycling titanium alloy ingot scraps throughout the entire process according to claim 1, characterized in that, In step four, the gap between the consumable electrode and the crystallizer in the first melting of the three melting processes is between 35mm and 65mm.

7. The method for recycling titanium alloy ingot scraps throughout the entire process according to claim 1, characterized in that, In step four, when the first of the three melting processes reaches a melting point of 1000kg±100kg, the process transitions from the arc-starting period to the normal melting period, reducing the melting current by 1kA and the melting voltage by 1V.

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