A detection and evaluation method for Ti6Al4V titanium alloy recycled chip material purification treatment

Abstract

This invention discloses a method for purifying and evaluating Ti6Al4V titanium alloy recycled scrap, belonging to the field of titanium alloy material processing technology. The method first involves remelting each batch of recycled titanium alloy scrap into laboratory-grade small button ingots to prepare button ingots with uniform composition. Subsequently, inductively coupled plasma spectroscopy and electron probe microanalysis are used to systematically detect and analyze the main element content and trace impurity elements in the button ingots. This invention cleverly transforms the detection of discrete, heterogeneous scrap into the detection of homogeneous standard ingots by remelting titanium alloy scrap with varying shapes and uneven contamination into laboratory-grade small button ingots. This completely eliminates the significant sampling errors and detection biases caused by direct scrap detection due to factors such as high sampling randomness, the mixing of oxide scale and metal matrix, and uneven distribution of surface contaminants. The composition of the button ingots can accurately and stably reflect the average purity level of the entire batch of scrap.

Description

Technical Field

[0001] This invention belongs to the field of titanium alloy element detection technology, specifically relating to a method for detecting and evaluating the purification treatment of Ti6Al4V titanium alloy recycled scrap. Background Technology

[0002] Ti6Al4V titanium alloy (whose main elemental composition is Al, V, Fe, and O, with a small amount of impurities) is widely used in aerospace, shipbuilding, chemical, and medical fields due to its high specific strength, excellent corrosion resistance, and good biocompatibility. During the processing of titanium alloy parts, a large amount of recyclable materials such as turning and milling chips are generated (approximately 50% to 80% of the input material). Recycling these recyclable materials is of great significance for reducing production costs, conserving strategic resources, and mitigating environmental impact.

[0003] However, recycled scrap is highly susceptible to contamination by impurities such as Fe, W, Si, S, P, Cl, and Cu during processing and storage, and it also absorbs moisture and grease, forming an oxide film on its surface. Direct remelting and reuse of this scrap can lead to excessive composition in the final ingot, metallurgical defects, and severe damage to alloy properties. Therefore, recycled scrap must undergo rigorous cleaning, sorting, degreasing, and drying before remelting. However, the industry currently lacks a scientific, unified, and effective standard method to evaluate whether these treated scraps meet remelting requirements.

[0004] Traditional evaluation methods often involve directly sampling the scrap material and then analyzing its composition through chemical or spectral analysis. This method has significant drawbacks: First, the scrap material is irregular in shape, has a large surface area, and exhibits uneven surface contamination and oxide film thickness, resulting in extremely poor representativeness from direct sampling. The analysis results fluctuate greatly and cannot accurately reflect the overall condition of the batch. Second, direct analysis makes it difficult to observe the microscopic distribution of impurity elements. Even if some harmful impurities have low average content, if they exist in an agglomerated form, they can form localized brittle phases during subsequent smelting, becoming crack initiation points and severely affecting material properties.

[0005] Therefore, developing an evaluation method that can accurately and comprehensively reflect the purity of recycled titanium alloy scrap has become a key technological bottleneck in promoting the efficient and high-value utilization of recycled titanium alloy materials. Summary of the Invention

[0006] To address the shortcomings of existing technologies, the present invention aims to provide a method for testing and evaluating the purification treatment of Ti6Al4V titanium alloy recycled scrap. This method solves the technical problems of existing technologies in evaluating the purity of titanium alloy recycled scrap, which suffer from poor representativeness, large fluctuations in results, and inability to detect the microscopic agglomeration morphology of impurities, making it difficult to accurately assess material properties due to direct sampling and analysis of the scrap.

[0007] To solve the above-mentioned technical problems, the present invention adopts the following technical solution: A purification treatment and evaluation method for Ti6Al4V titanium alloy scrap is proposed. This method first involves laboratory-scale small-scale ingot melting of each batch of recycled titanium alloy scrap to prepare uniformly composed ingots. Then, inductively coupled plasma spectroscopy (ICP) and electron probe microanalysis (EPMA) are used to systematically detect and analyze the content of major elements and trace impurities in the ingots. ICP is used to accurately determine whether the contents of major elements such as Al, V, Fe, and O basically meet the internal control composition range, while EPMA is used to finely detect the content of trace impurities such as W, Si, S, P, Cl, and Cu, and to assess whether their distribution morphology exhibits harmful agglomeration.

[0008] Specifically, the method includes the following steps: Step 1: Take a sample from a batch of purified Ti6Al4V titanium alloy recycled scrap, mix it evenly, and weigh it accurately.

[0009] Step 2: Using vacuum arc melting, the Ti6Al4V titanium alloy recycled scrap weighed in Step 1 is melted into a button ingot.

[0010] Step 3: Cut a sample from the core area of ​​the button ingot obtained in Step 2, then cut it into chips. Inductively coupled plasma atomic emission spectrometry (ICP-AES) is used to detect the aluminum, vanadium, and iron content in the sample, followed by inert gas melting. Infrared absorption method is used to detect the oxygen content in a sample.

[0011] Step 4: Cut a metallographic sample from another location on the button ingot, polish it, and use an electron probe microanalyzer to analyze and obtain the surface distribution test data of aluminum and vanadium in the metallographic sample; then perform point-to-point quantitative analysis and surface scanning analysis on the impurity elements.

[0012] Step 5: If the test results in Step 3 show that the content of all major elements is lower than the internal control standard limit, and the test results in Step 4 show that there is no significant agglomeration of all impurity element signal points, then this batch of purified Ti6Al4V titanium alloy recycled scrap is determined to be a qualified product; if any of the above conditions are not met (i.e., the content of major elements exceeds the standard, or the content of any impurity element exceeds the standard, or although the content does not exceed the standard, there is obvious harmful agglomeration), then the purified Ti6Al4V titanium alloy recycled scrap is determined to be a non-qualified product.

[0013] The present invention also has the following technical features: Specifically, in step two, before melting, a vacuum is drawn until the vacuum level inside the furnace reaches 6.5 × 10⁻⁶. - 3Pa.

[0014] Specifically, in step two, during smelting, the melting temperature is 1640–1680℃, and the temperature difference between the bottom of the melt and the crystal growth interface is 320–380℃.

[0015] Specifically, in step two, the vacuum degree during melting is 5×10-3~1×10-2 Pa.

[0016] Specifically, in step two, during melting, the power of the main coil at the bottom of the crucible is 8-10kW, the power of the auxiliary coil at the top is 2.5-3.5kW, and the hot top feeding holding time is 12-18s.

[0017] Specifically, in step two, after the melting is completed, the cooling rate is 80-120℃ / s.

[0018] Specifically, in step three, the core area of ​​the button ingot is the region 1.8–2.2 mm from the bottom dense layer and 1.2–1.8 mm inside the natural solidification zone at the edge.

[0019] Specifically, in step three, the cutting conditions are: a cutting speed of 75–85 m / min and a depth of cut of 0.148–0.152 mm.

[0020] Specifically, in step three, the inert gas melts. The conditions for infrared absorption spectroscopy are: analytical power of 4.6–5.0 kW and purge flow rate of 1.7–1.9 L / min.

[0021] Specifically, in step four, the polishing conditions are as follows: magnetorheological polishing assisted by 0.4–0.6 wt% hydrofluoric acid mist is used, and the polishing pressure is 0.148–0.152 MPa.

[0022] Specifically, in step four, when using an electron probe microanalyzer (EPMA) for analysis, the natural solidified shell region with an edge thickness of 40–60 μm on the button ingot is used as the internal standard, and the accelerating voltage of the electron probe microanalyzer is calibrated to 14–16 kV.

[0023] Specifically, in step four, the impurity elements include tungsten, silicon, sulfur, phosphorus, chlorine, and copper.

[0024] The beneficial technical effects of this invention compared to the prior art are as follows: (I) This invention cleverly transforms the detection of discrete, heterogeneous scrap into the detection of homogeneous standard ingots by remelting titanium alloy scrap of varying shapes and uneven contamination. This completely eliminates the significant sampling errors and detection biases caused by the large randomness of sampling, the mixing of oxide scale and metal matrix, and the uneven distribution of surface contaminants when directly detecting scrap. As a homogenized entity, the button ingot itself can accurately and stably reflect the average purity level of the entire batch of scrap.

[0025] (II) This invention innovatively integrates two advanced analytical techniques: inductively coupled plasma spectroscopy (ICP) and electron probe microanalysis (EPMA), constructing a multi-dimensional evaluation system from macroscopic average to microscopic distribution. ICP technology efficiently and accurately determines whether the content of major elements such as Al, V, Fe, and O in recycled materials meets internal control standards, providing a macroscopic understanding of the compliance of the matrix composition. The introduction of EPMA technology deepens and expands the evaluation dimensions: it not only enables highly sensitive quantitative detection of trace impurity elements such as W, Si, S, P, Cl, and Cu, but more importantly, it can visually reveal the distribution morphology of these harmful elements in button ingots with micron-level spatial resolution. This allows the invention to accurately identify the potential risk of "average content being qualified but localized harmful agglomeration," which is unattainable by traditional methods relying solely on average component detection. Through dual control of the "quantity" and "shape" of impurity elements, the evaluation conclusions are more in-depth, comprehensive, and safe.

[0026] (III) When the evaluation results obtained using the method of this invention are unqualified, the analytical data of EPMA can clearly indicate which impurity element (such as high-density W inclusions, segregation of low-melting-point Sn or Cl, etc.) caused the problem, and can clearly present its specific form of existence (such as local enrichment, distribution along grain boundaries, etc.). This precise traceability capability provides clear and direct feedback and directional guidance for the improvement of upstream waste material pretreatment, cleaning, crushing, sorting and other purification processes. Process personnel can optimize specific links such as degreasing, degassing, magnetic separation, and gravity separation in a targeted manner according to the type of problem, thereby significantly improving the efficiency and effect of process improvement and achieving closed-loop optimization.

[0027] (IV) The evaluation method of this invention has a clear process, and the core links (button ingot smelting parameters, ICP and EPMA testing points) are clearly defined. It is technically highly operable and easily replicated and promoted among different enterprises and testing institutions. This method establishes a scientific, unified, and objective quantitative evaluation standard for the purity of titanium alloy recycled scrap, and is expected to provide a solid technical foundation for the future formulation of relevant industry standards or national standards. This is of significant practical importance for regulating the titanium alloy recycling market, promoting the large-scale production and application of high-quality recycled titanium alloys, and driving the green and sustainable development of the titanium industry. Attached Figure Description

[0028] Figure 1 The flowchart shows the testing and evaluation method for the purification treatment of Ti6Al4V titanium alloy recycled scrap.

[0029] Figure 2 This is a photograph of a button ingot made from recycled titanium alloy scrap.

[0030] Figure 3 The results of EPMA sulfur analysis of the titanium alloy recycled scrap ingot sample from Example 1 are presented.

[0031] Figure 4 The results of EPMA sulfur analysis of the titanium alloy recycled scrap smelting ingot sample from Example 2 are presented.

[0032] Figure 5 The results of EPMA sulfur (S) elemental analysis of the titanium alloy recycled scrap smelting ingot sample from Example 3 are presented.

[0033] Figure 6 The results of EPMA sulfur (S) elemental analysis of the titanium alloy recycled scrap smelting ingot sample in Example 4 are presented.

[0034] Figure 7 The results of EPMA sulfur (S) elemental analysis of the titanium alloy recycled scrap smelting ingot sample in Example 5 are presented.

[0035] Figure 8 The EPMA sulfur (S) elemental analysis of the titanium alloy recycled scrap smelting ingot sample in Example 6 is shown.

[0036] The technical solution of the present invention will be further described below with reference to the embodiments. Detailed Implementation

[0037] It should be noted that, unless otherwise specified, all raw materials and purification methods used in this invention are those known in the art. For example, the purification method for Ti6Al4V titanium alloy recycled shavings adopts conventional methods known in the prior art.

[0038] To accurately evaluate the effectiveness of the purification treatment of recycled titanium alloy scrap, the present invention adopts the following technical approach: First, from the same batch of recycled titanium alloy scrap that has undergone purification treatment such as cleaning and drying, for example, a certain mass (about 130g) of sample can be randomly weighed from every 200kg of scrap to ensure the representativeness of the sample.

[0039] Next, the obtained scrap samples are subjected to vacuum induction levitation melting. Melting is carried out under a high vacuum or high-purity inert atmosphere, completely melting and cooling the scrap to form a small ingot with relatively homogeneous composition, i.e., a "button ingot". The purpose of this step is to transform the scrap, which has various shapes and may have uneven composition, into a standard solid sample with homogeneous composition, completely eliminating the sampling deviation problem caused by directly testing the scrap.

[0040] Subsequently, samples were machined from the obtained button ingots to prepare chemical analysis samples. Inductively coupled plasma optical emission spectrometry (ICP-OES or ICP-MS) was used to accurately determine the content of the main elements in the titanium alloy. For example, for Ti6Al4V alloy, the contents of the four key elements Al, V, Fe, and O were mainly detected. The determination results were then rigorously compared with the internal control standards for this alloy grade.

[0041] Simultaneously, a metallographic sample was taken from the prepared button ingot, and after grinding and polishing, it was made into an analytical sample. Electron probe microanalysis (EPMA) was used to analyze this sample. EPMA has extremely high capabilities for micro-area compositional analysis and elemental surface distribution analysis. It was used to detect the content (point analysis) of trace impurity elements such as W, Si, S, P, Cl, and Cu, and the surface scanning function allowed for direct observation of the distribution morphology of these impurity elements in the microstructure, determining whether there were obvious aggregation or enrichment phenomena.

[0042] Finally, based on the combined test results from steps three and four, a final judgment is made: If the content of all major elements (such as Al, V, Fe, and O) is within the internal control standard range; and the content of all specified impurity elements (such as W, Si, S, P, Cl, and Cu) is below the internal control limit threshold; and the EPMA surface scan results show that these impurity elements are diffusely and uniformly distributed, without continuous network, strip, or cluster-like harmful agglomeration forms, then the batch of recycled scrap is deemed unqualified for purity and must be returned for reprocessing or downgraded for use.

[0043] Following the above technical solutions, specific embodiments of the present invention are given below. It should be noted that the present invention is not limited to the following specific embodiments, and all equivalent modifications made based on the technical solutions of this application fall within the protection scope of the present invention.

[0044] Example 1 This embodiment provides a method for testing and evaluating the purification treatment of Ti6Al4V titanium alloy scrap, which specifically includes the following steps: Step 1: Take 10 samples from different positions and depths from a batch of processed Ti6Al4V titanium alloy recycled shavings using a sampling shovel, mix them evenly, and then accurately weigh 130kg.

[0045] Step 2: Load 130 kg of scrap material into a vacuum arc furnace containing a water-cooled copper crucible. Evacuate the furnace until the vacuum level reaches 6.5 × 10⁻⁶. -3 After Pa, all the scrap is melted into a single button ingot. Once melted, it is cooled to room temperature before being removed from the furnace.

[0046] Button ingot smelting parameter control range: vacuum degree controlled at 5×10 -3 ~1×10 -2 Pa, melting temperature 1660±20℃, bottom main coil power 8~10kW, top auxiliary coil power 3.0±0.5kW, upper and lower temperature difference maintained at 320~380℃, hot top shrinkage holding time 15±3s, cooling rate controlled at 80~120℃ / s, to obtain recycled Ti6Al4V titanium alloy button ingots without shrinkage cavities and segregation.

[0047] Step 3: Using a wire EDM machine, cut a 50.0±0.5g sample from the core area of ​​the button ingot, 2.0±0.2mm from the bottom dense layer and 1.5±0.3mm inside the natural shell zone at the edge. Turn the sample into chips using a cutting speed of 80±5m / min and a depth of cut of 0.15±0.02mm. Perform ICP analysis. The content of Al, V, and Fe elements was determined by OES method, using inert gas melting. The O content was determined by infrared absorption under the conditions of analytical power of 4.8±0.2kW and purging flow rate of 1.8±0.1L / min.

[0048] Step 4: A metallographic sample was cut from another location on the button ingot. Magnetorheological polishing was performed using HF acid mist assisted by a mass fraction of 0.5±0.1%, with the polishing pressure controlled at 0.15±0.02 MPa, to achieve a polished surface with no deformation and prominent grain boundaries. Subsequently, observation was conducted using an electron probe microanalysis (EPMA). Using the naturally solidified shell region with a thickness of 50±10 μm at the edge of the button ingot as an internal standard, the surface distribution data of Al and V elements under an EPMA accelerating voltage of 15±1 kV were calibrated, with a test error ≤0.15%. The results showed no abnormally bright enriched phases. Further point-to-point quantitative analysis and surface scanning analysis were then performed on elements such as W, Si, S, P, Cl, and Cu.

[0049] Step 5: Evaluate the purity of this batch of Ti6Al4V recycled scrap by combining the results of Step 3 and Step 4.

[0050] In this embodiment, the detection results in step three are: Al 6.1%, V 4.0%, Fe 0.20%, O 0.12%. Compared with the internal control standard for Ti6Al4V alloy (Al: 5.7-6.5%, V: 3.6-4.4%, Fe≤0.25%, O≤0.15%), all major elements are qualified. In step four, point analysis shows that the contents of each impurity element are: W<0.002%, Si<0.01%, S<0.006%, P<0.007%, Cl<0.001%, Cu<0.005%, all lower than the internal control standard limits. EPMA surface scan analysis shows (see...) Figure 3All impurity element signal points are sparsely and uniformly distributed, without forming continuous network, strip, or obvious cluster enrichment regions, i.e., there is no significant agglomeration.

[0051] The results above show that the main elements are qualified in step three, and the impurity element content is qualified and evenly distributed in step four. Therefore, the purity treatment of this batch of Ti6Al4V recycled scrap is deemed qualified, and it can be used for subsequent large-scale feeding for vacuum arc remelting.

[0052] Example 2: This embodiment provides a method for testing and evaluating the purification treatment of Ti6Al4V titanium alloy recycled scrap, which is exactly the same as the process and parameters in Embodiment 1.

[0053] In this embodiment, the ICP results in step three show that the main elements are qualified. Observation under an electron probe microanalyzer (EPMA) and EPMA surface scan analysis show (see...) Figure 4 All impurity element signal points were sparsely and uniformly distributed, without forming continuous network, strip, or obvious clustered enrichment areas, i.e., no significant agglomeration. Considering the results of steps three and four (main elements were qualified, impurity element content was qualified and uniformly distributed), the purity treatment of this batch of Ti6Al4V recycled scrap was deemed qualified.

[0054] Example 3: This embodiment provides a method for testing and evaluating the purification treatment of Ti6Al4V titanium alloy recycled scrap, which is exactly the same as the process and parameters in Embodiment 1.

[0055] In this embodiment, the ICP results in step three showed that the main elements were acceptable, but the EPMA surface scan in step four revealed obvious micro-clustering and grain boundary aggregation of the S element (see [link to relevant documentation]). Figure 5 Although the average content did not exceed the internal control standard, the batch of scrap was ultimately deemed unqualified in terms of purity due to the presence of harmful agglomerates. This result guided production personnel to inspect the cleaning process, which revealed that a loophole in the sorting and processing steps led to a small amount of cleaning fluid contaminating the scrap.

[0056] Example 4: This embodiment provides a method for testing and evaluating the purification treatment of Ti6Al4V titanium alloy recycled scrap, which is exactly the same as the process and parameters in Embodiment 1.

[0057] In this embodiment, the ICP results in step three showed that the main elements were qualified, but the EPMA surface scan in step four revealed obvious micro-cluster enrichment of the S element (see...). Figure 6Although the average content did not exceed the internal control standard, the batch of scrap was ultimately deemed unqualified in terms of purity due to the presence of harmful segregation. This result guided production personnel to inspect the cleaning process, revealing that a loophole in the sorting and processing steps led to a small amount of cleaning fluid contaminating the scrap. The degree of sulfur element segregation in this embodiment was lower than that in Example 1.

[0058] Example 5: This embodiment provides a method for testing and evaluating the purification treatment of Ti6Al4V titanium alloy recycled scrap, which is exactly the same as the process and parameters in Embodiment 1.

[0059] In this embodiment, the ICP results in step three showed that the main elements were qualified, but the EPMA surface scan in step four revealed obvious micro-cluster enrichment of the S element (see...). Figure 7 Although the average content did not exceed the internal control standard, the batch of scrap was ultimately deemed unqualified in terms of purity due to the presence of harmful agglomerates. This result guided production personnel to inspect the cleaning process, which revealed that a loophole in the sorting and processing steps led to a small amount of cleaning fluid contaminating the scrap.

[0060] Example 6: This embodiment provides a method for testing and evaluating the purification treatment of Ti6Al4V titanium alloy recycled scrap, which is exactly the same as the process and parameters in Embodiment 1.

[0061] In this embodiment, the ICP results in step three show that the principal elements are qualified, but the EPMA surface scan in step four reveals significant enrichment of the S element (see...). Figure 8 However, this batch of scrap did not exhibit the micro-cluster enrichment seen in the comparative example, and the degree of sulfur element aggregation was lower than that in the comparative example. Although the average content did not exceed the internal control standard, the presence of harmful aggregation ultimately led to the batch being deemed unqualified for purity. This result guided production personnel to inspect the cleaning process, revealing that a loophole in the sorting and processing steps resulted in a small amount of cleaning fluid contaminating the scrap.

[0062] The final results of the above embodiments are summarized in the following table: Table 1. Product quality evaluation results of Examples 1 to 6

[0063] The results above demonstrate that the method of this invention exhibits excellent discrimination and stability when used to test multiple batches of samples. By transforming complex scrap into homogeneous button ingots for systematic analysis, this invention effectively eliminates detection interference caused by differences in scrap morphology and surface contamination, enabling the combined ICP and EPMA detection data to accurately and consistently reflect the essential differences in purity among batches of samples. The results of the embodiments confirm that this method can not only accurately determine the compliance of the main element composition but also keenly capture the content fluctuations and microscopic distribution characteristics of trace impurity elements, thus providing a comprehensive, objective, and quantifiable scientific evaluation of the purification effect of each batch of recycled scrap. This result fully verifies the effectiveness and universality of this invention as a key technology for quality control of titanium alloy recycled scrap.

Claims

1. A method for testing and evaluating the purification treatment of Ti6Al4V titanium alloy recycled scrap, characterized in that, The method includes the following steps: Step 1: Take a sample from a batch of purified Ti6Al4V titanium alloy recycled scrap, mix it evenly, and weigh it accurately. Step 2: Using vacuum arc melting, the Ti6Al4V titanium alloy recycled scrap weighed in Step 1 is melted into a button ingot. Step 3: Cut a sample from the core area of ​​the button ingot obtained in Step 2, then cut it into chips. Inductively coupled plasma atomic emission spectrometry (ICP-AES) is then used to detect the aluminum, vanadium, and iron content in the sample, followed by inert gas melting. Infrared absorption method for detecting oxygen content in samples; Step 4: Cut a metallographic sample from another location on the button ingot, polish it, and use an electron probe microanalyzer to analyze and obtain the surface distribution test data of aluminum and vanadium in the metallographic sample; then perform point-to-point quantitative analysis and surface scanning analysis on the impurity elements. Step 5: If the test results in Step 3 show that the content of the main elements is lower than the internal control standard limit, and the test results in Step 4 show that the distribution of all impurity element signal points is not significantly agglomerated, then this batch of purified Ti6Al4V titanium alloy recycled scrap is determined to be a qualified product; if any of the above conditions are not met, then the purified Ti6Al4V titanium alloy recycled scrap is determined to be a non-qualified product.

2. The method for testing and evaluating the purification treatment of Ti6Al4V titanium alloy recycled scrap as described in claim 1, characterized in that, In step two, during smelting, the melting temperature is 1640–1680℃, and the temperature difference between the bottom of the melt and the crystal growth interface is 320–380℃.

3. The method for testing and evaluating the purification treatment of Ti6Al4V titanium alloy recycled scrap as described in claim 1, characterized in that, In step two, after the melting is completed, the cooling rate is 80-120℃ / s.

4. The method for testing and evaluating the purification treatment of Ti6Al4V titanium alloy recycled scrap as described in claim 1, characterized in that, In step three, the core area of ​​the button ingot is the region 1.8–2.2 mm from the bottom dense layer and 1.2–1.8 mm inside the natural solidification zone at the edge.

5. The method for testing and evaluating the purification treatment of Ti6Al4V titanium alloy recycled scrap as described in claim 1, characterized in that, In step three, the cutting conditions are: cutting speed of 75-85 m / min and depth of cut of 0.148-0.152 mm.

6. The method for testing and evaluating the purification treatment of Ti6Al4V titanium alloy recycled scrap as described in claim 1, characterized in that, In step three, the inert gas melts. The conditions for infrared absorption spectroscopy are: analytical power of 4.6–5.0 kW and purge flow rate of 1.7–1.9 L / min.

7. The method for testing and evaluating the purification treatment of Ti6Al4V titanium alloy recycled scrap as described in claim 1, characterized in that, In step four, the polishing conditions are as follows: 0.4-0.6 wt% hydrofluoric acid mist is used for magnetorheological polishing, and the polishing pressure is 0.148-0.152 MPa.

8. The method for testing and evaluating the purification treatment of Ti6Al4V titanium alloy recycled scrap as described in claim 1, characterized in that, In step four, when using an electron probe microanalyzer for analysis, the natural solidified shell region with an edge thickness of 40–60 μm on the button ingot is used as the internal standard.

9. The method for testing and evaluating the purification treatment of Ti6Al4V titanium alloy recycled scrap as described in claim 1, characterized in that, In step four, when using an electron probe microanalyzer for analysis, the accelerating voltage of the electron probe microanalyzer is calibrated to be 14–16 kV.

10. The method for testing and evaluating the purification treatment of Ti6Al4V titanium alloy recycled scrap as described in claim 1, characterized in that, In step four, the impurity elements include tungsten, silicon, sulfur, phosphorus, chlorine, and copper.

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