A deep step high-precision milling method suitable for various types of titanium alloy

Abstract

A kind of deep step high-precision milling method suitable for multiple models of titanium alloy, the component of the milling solution used is nitric acid: 65% nitric acid with mass percentage concentration, content is 250-400g / L;Hydrofluoric acid: 40% hydrofluoric acid with mass percentage concentration, content is 120-180g / L;Urea: content is 10-18g / L;Octyl phenol polyoxyethylene ether: content is 1-4g / L;Sodium dodecyl sulfate: content is 0.1-0.4g / L;Sugar-based Gemini cationic surfactant SGCS: content is 0.1-0.4g / L;Amino sulfonate Gemini surfactant AHS-14: content is 0.1-0.4g / L;The rest is water.The milling method provided by the application is suitable for milling of TC1, TC4, TA12A, TA15 and other multiple models of titanium alloy, especially suitable for deep step (depth >=3mm) milling of various complex shape titanium alloy.

Description

Technical Field

[0001] This invention relates to the field of metal chemical and electrochemical machining technology, and in particular to a deep step high-precision chemical milling method applicable to various types of titanium alloys, suitable for deep high-precision chemical milling of titanium alloys with a chemical milling depth ≥3mm. Background Technology

[0002] Chemical milling, or "chemical milling" for short, is a special machining method that uses chemical corrosive solutions such as acids, alkalis, and salts to corrode and dissolve the surface of the metal to be machined, thereby changing the size and shape of the workpiece. Chemical milling does not produce the stress, burrs, or other defects associated with mechanical machining, and the workpiece is less prone to deformation. Therefore, it is widely used for machining thin-walled parts, reducing structural weight, and processing complex shapes and fine structures.

[0003] Titanium and titanium alloys, with their advantages of high specific strength, good corrosion resistance, and high thermal strength, have seen increasing use in aircraft and aero engines in recent years. In some new-generation fighter jets abroad, the amount of titanium alloy used reaches over 40%, and the amount of titanium alloy used in Chinese aircraft is also continuously increasing. However, titanium alloys have poor machinability due to their high coefficient of friction, low thermal conductivity, and high hardness. Chemical milling can effectively solve this problem, and therefore, chemical milling is increasingly used for weight reduction and precision structural machining of titanium alloy components in aircraft and aero engines.

[0004] Carpmaels et al. proposed chemical milling of α-β titanium alloys at 50–60°C using a solution containing 2%–7% HF and 3%–10% HCl, achieving hydrogen absorption of <10 ppm. Coggins et al. proposed a chemical milling solution composed of hydrofluoric acid, nitric acid, carboxylic acid derivatives, and sodium benzoate for chemical milling of titanium alloys, resulting in a uniform milled surface and low hydrogen absorption; however, acid mist easily escapes during processing, polluting the environment, corroding equipment, and affecting human health. In 2008, Yin Maosheng et al. proposed a titanium alloy chemical milling solution containing nitric acid, hydrofluoric acid, sodium dodecyl sulfate, ethylene glycol n-butyl ether, urea, and sodium nitrate, achieving good milled surface quality and hydrogen absorption of <9 ppm; however, the ethylene glycol n-butyl ether in the solution is highly toxic, resulting in poor acid mist suppression and making it unsuitable for deep-step chemical milling. In 2015, Sun Fuquan et al. proposed a titanium alloy sawtooth shallow step precision milling solution and process. The solution used was a titanium alloy milling solution with nitric acid, hydrofluoric acid, sodium dodecyl sulfate, and ethylene glycol monobutyl ether. The process formula used low-toxicity ethylene glycol monobutyl ether to replace the more toxic ethylene glycol n-butyl ether. The milling effect was not as good as the former, and it could not suppress acid mist emission. Moreover, it was only suitable for shallow step milling. In 2009, Wen Qingjie et al. proposed an environmentally friendly chemical milling process for titanium alloys. The chemical milling solution consisted of hydrofluoric acid, nitric acid, carbonic acid derivatives, alkyl sulfonates, and polyethylene glycol-based surfactants. This process exhibited good performance across the board, with a single-sided milling speed of 0.010–0.020 mm / min, a post-milling surface roughness of <0.8 μm, hydrogen absorption of <7 ppm, no intergranular or end-grain corrosion, and good acid mist suppression. The additives in the solution were both anionic and nonionic surfactants, which had a synergistic effect in improving the quality of the chemical milling. However, this process was only suitable for shallow-step chemical milling (milling depth ≤1 mm). In general, current titanium alloy chemical milling processes are difficult to apply to deep-step milling; for deep-step milling (milling depth ≥3 mm), surfactants with higher activity should be used.

[0005] Currently, titanium alloy components such as aero-engine casings, compressor disks, and blades widely employ chemical milling for weight reduction. However, these components have complex structures, exhibiting significant torsion and bending, small radii of curvature, or narrow rib widths in the chemical milling zone. Some structural components require deep-step chemical milling (milling depth ≥ 3 mm). Existing chemical milling processes for deep-step titanium alloy machining present numerous challenges. For instance, with increasing milling depth (≥ 1 mm), gas accumulation and retention easily occur in the fillet areas and transition zones, hindering the diffusion of corrosion products and causing localized defects. Furthermore, precise control of deep-step milling accuracy is difficult, including aspects such as flatness, line offset, and corrosion ratio. Additionally, existing titanium alloy chemical milling processes suffer from acid mist emission. The acid mist, mixed with strong acids, can damage equipment, pollute the environment, and harm human health, thus limiting the development of this technology. Summary of the Invention

[0006] The main objective of this invention is to propose a high-precision milling method for deep steps applicable to various types of titanium alloys, aiming to solve the aforementioned technical problems.

[0007] To achieve the above objectives, this invention proposes a high-precision chemical milling method for deep steps applicable to various types of titanium alloys. The chemical milling solution comprises nitric acid, hydrofluoric acid, urea, octylphenol polyoxyethylene ether, sodium dodecyl sulfate, glycosyl gemini cationic surfactant SGCS, aminosulfonate gemini surfactant AHS-14, and water; the content of each component is as follows:

[0008] Nitric acid: Nitric acid with a mass percentage concentration of 65% and a content of 250–400 g / L;

[0009] Hydrofluoric acid: Hydrofluoric acid with a mass percentage concentration of 40% and a content of 120-180 g / L;

[0010] Urea: content is 10-18 g / L;

[0011] Octylphenol polyoxyethylene ether: content is 1-4 g / L;

[0012] Sodium dodecyl sulfate: content is 0.1–0.4 g / L;

[0013] Glycosyl gemini cationic surfactant SGCS: content of 0.1–0.4 g / L;

[0014] Aminosulfonate type gemini surfactant AHS-14: content 0.1~0.4g / L;

[0015] The remainder is water.

[0016] Preferably, the content of each component in the chemical milling solution is as follows:

[0017] Nitric acid with a mass percentage concentration of 65% is 300-365 g / L;

[0018] Hydrofluoric acid with a mass percentage concentration of 40% is 125–160 g / L;

[0019] Urea: 12-15 g / L;

[0020] Octylphenol polyoxyethylene ether: 2-3 g / L;

[0021] Sodium dodecyl sulfate: 0.2–0.3 g / L;

[0022] Glycosyl gemini cationic surfactant SGCS: 0.2–0.3 g / L;

[0023] Aminosulfonate type gemini surfactant AHS-14: 0.2–0.3 g / L;

[0024] Water: content ranges from 396.8 to 618.7 g / L.

[0025] Preferably, a high-precision milling method for deep steps applicable to various types of titanium alloys is characterized by comprising the following steps:

[0026] Step S1: Clean and dry the workpiece;

[0027] Step S2: Coat the workpiece surface obtained in step S1 with a peelable protective coating. Allow the coating to dry and cure naturally into a film for 24 hours. Then, engrave the chemical milling pattern on the protective film and peel off the protective film from the chemical milling area.

[0028] Step S3: The workpiece obtained in step S3 is then placed into the chemical milling solution for chemical milling. The chemical milling time is determined by the required chemical milling depth and the chemical milling speed.

[0029] Step S4: Once the chemical milling depth is reached, immediately remove the workpiece, clean off any residual chemical milling solution on the workpiece surface, and peel off all protective layers after drying.

[0030] Preferably, in step S1, hot alkali is used to remove surface dust and oil from the workpiece to be chemically milled, the workpiece is cleaned with hot water and cold water respectively, and then the workpiece is placed in an acid solution containing HF for pickling to obtain a smooth surface. Then it is cleaned with cold water and hot water at 70℃~80℃ respectively, and finally dried.

[0031] Preferably, in step S3, the temperature is controlled at 25-35°C during chemical milling, and the chemical milling solution is thoroughly stirred during the process. The purpose is to reduce the influence of concentration and temperature gradient, and to form a fine and dense foam layer on the solution surface to suppress the escape of acid mist.

[0032] Preferably, in step S4, the residual chemical milling solution on the workpiece surface is thoroughly rinsed off with warm water at 40℃~50℃.

[0033] Due to the adoption of the above technical solution, the beneficial effects of the present invention are as follows:

[0034] (1) The chemical milling method provided by the present invention is suitable for chemical milling of various types of titanium alloys such as TC1, TC4, TA12A, and TA15, and is especially suitable for chemical milling of deep steps (depth ≥ 3mm) of titanium alloys with various complex shapes.

[0035] (2) The chemical milling solution contains sodium dodecyl sulfate and octylphenol polyoxyethylene ether, which has strong foaming ability. Under the synergistic effect of aminosulfonate-type gemini surfactant and glycosyl gemini cationic surfactant, the foaming ability of the chemical milling solution is even stronger and more stable. During the chemical milling process, the surfactant molecules are oriented on the surface of the chemical milling solution, in a stacked state, and overlap with the urea foaming film to form a dense foam liquid film, which uniformly covers the surface of the chemical milling tank, inhibiting the escape and diffusion of acid mist; acid mist can be reduced by more than 90%.

[0036] (3) Anionic surfactants, geminocation surfactants, nonionic surfactants and amphoteric surfactants in the chemical milling solution form a multi-component complex system, namely anionic-cationic surfactant complex system, anionic-amphoteric surfactant complex system, anionic-nonionic surfactant complex system and cationic-nonionic surfactant complex system. Under the synergistic effect of each other, they produce a strong positive additive and synergistic effect, which greatly improves the quality of deep step chemical milling.

[0037] (4) The multi-component compound system forms new mixed micelles inside the chemical milling solution. Its critical micelle concentration is much lower than that of any single surfactant, and it greatly reduces the surface tension of the chemical milling solution. During chemical milling, defects such as air grooves, ripples, protrusions, and depressions at the deep step transition zone and fillets can be eliminated. It can also greatly improve the wetting effect of the chemical milling solution on the workpiece surface and reduce the surface tension. At the same time, it greatly improves the corrosion uniformity of the chemical milling solution on the milled surface and greatly improves the contour quality.

[0038] (5) The quality and efficiency of chemical milling are higher than those of existing chemical milling processes. The chemical milling speed can reach 25-35 μm / min on one side. The surface roughness Ra of chemical milling is ≤0.6 μm, the flatness is ±0.05 mm, the hydrogen absorption is <3 ppm, and there is no crystal end or intergranular corrosion.

[0039] (6) The chemical milling solution has a relatively simple composition, the raw materials are low in toxicity and easy to purchase, it is stable and not easily decomposed during the processing, and the solution is easy to maintain. Detailed Implementation

[0040] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0041] Example 1:

[0042] The chemical milling solution has the following composition:

[0043] The content of nitric acid with a mass percentage concentration of 65% is 250 g / L;

[0044] The content of hydrofluoric acid with a mass percentage concentration of 40% is 120 g / L;

[0045] The urea content is 10g / L;

[0046] The content of octylphenol polyoxyethylene ether is 1 g / L;

[0047] The sodium dodecyl sulfate content is 0.1 g / L.

[0048] The SGCS content is 0.1 g / L.

[0049] The content of AHS-14 was 0.1 g / L.

[0050] The water content is 618.7 g / L.

[0051] The specific steps of chemical milling TC4 titanium alloy include the following:

[0052] Step S1: Clean and dry the workpiece; specifically, use hot alkali to remove surface dust and oil from the workpiece to be chemically milled, clean the workpiece with hot water and cold water respectively, then put the workpiece into an acid solution containing HF for pickling to obtain a smooth surface, then clean it with cold water and hot water at 70℃~80℃ respectively, and finally dry it.

[0053] Step S2: Coat the surface of the workpiece obtained in step S1 with a peelable protective coating. Allow the coating to dry and cure naturally into a film for 24 hours. Then, engrave the chemical milling pattern on the protective film and peel off the protective film from the chemical milling area.

[0054] Step S3: The workpiece obtained in Step S3 is then placed in the chemical milling solution for chemical milling. The temperature is controlled at 30℃±2℃, and the chemical milling time is 120 minutes. During the chemical milling process, the solution is thoroughly stirred to reduce the influence of concentration and temperature gradient, and to form a fine and dense foam layer on the solution surface to suppress acid mist escape. The acid mist is absorbed using NaOH solution. The amount of acid mist generated with and without surfactant is determined by neutralization titration, and the acid mist suppression rate of the chemical milling solution is measured. During chemical milling, a dense, layered white foam layer forms on the surface of the chemical milling solution, and no acid mist odor is detected near the edge of the chemical milling tank. The acid mist suppression rate is 90%.

[0055] Step S4: Once the chemical milling depth is reached, immediately remove the workpiece and thoroughly rinse off any residual chemical milling solution on the workpiece surface with warm water at 40℃~50℃. After drying, peel off all protective layers.

[0056] The machining depth per unit time is used to measure the speed of chemical milling. In this embodiment, the thickness of the chemically milled area of ​​the workpiece was measured using a 35DL ultrasonic thickness gauge before and after machining. The chemical milling depth in this test was 3.088 mm, the chemical milling speed was 25.73 μm / min, and the flatness was ±0.04 mm. The surface roughness of the workpiece was measured using a Surtronic electric profilometer. The surface roughness before chemical milling was 0.75 μm, and the surface roughness after chemical milling was 0.59 μm.

[0057] Example 2:

[0058] Composition of chemical milling solution:

[0059] The content of nitric acid with a mass percentage concentration of 65% is 400 g / L;

[0060] The concentration of hydrofluoric acid with a mass percentage of 40% is 180 g / L.

[0061] The urea content is 18 g / L;

[0062] The content of octylphenol polyoxyethylene ether is 4 g / L;

[0063] The sodium dodecyl sulfate content is 0.4 g / L;

[0064] The SGCS content was 0.4 g / L.

[0065] The content of AHS-14 was 0.4 g / L.

[0066] The water content is 396.8 g / L.

[0067] The specific steps of chemical milling TA15 titanium alloy include the following:

[0068] Step S1: Clean and dry the workpiece; specifically, use hot alkali to remove surface dust and oil from the workpiece to be chemically milled, clean the workpiece with hot water and cold water respectively, then put the workpiece into an acid solution containing HF for pickling to obtain a smooth surface, then clean it with cold water and hot water at 70℃~80℃ respectively, and finally dry it.

[0069] Step S2: Coat the surface of the workpiece obtained in step S1 with a peelable protective coating. Allow the coating to dry and cure naturally into a film for 24 hours. Then, engrave the chemical milling pattern on the protective film and peel off the protective film from the chemical milling area.

[0070] Step S3: The workpiece obtained in Step S3 is then placed into the chemical milling solution for chemical milling. The temperature is controlled at 30℃±2℃, and the chemical milling time is 120 minutes. During the chemical milling process, the solution is thoroughly stirred to reduce the influence of concentration and temperature gradient, and to form a fine and dense foam layer on the solution surface to suppress acid mist escape. During chemical milling, a dense, layered white foam layer forms on the surface of the solution, and no acid mist odor can be detected near the edge of the chemical milling tank. The acid mist suppression rate is 95%.

[0071] Step S4: Once the chemical milling depth is reached, immediately remove the workpiece and thoroughly rinse off any residual chemical milling solution on the workpiece surface with warm water at 40℃~50℃. After drying, peel off all protective layers.

[0072] In this embodiment, the chemical milling depth was 4.108 mm, the chemical milling time was 120 min, the chemical milling speed was 34.23 μm / min, and the flatness was ±0.05 mm. The surface roughness of the workpiece was tested using a Surtronic electric profilometer. The surface roughness before chemical milling was 0.74 μm, and the surface roughness after chemical milling was 0.52 μm.

[0073] Example 3:

[0074] Composition of chemical milling solution:

[0075] The content of nitric acid with a mass percentage concentration of 65% is 325 g / L.

[0076] The concentration of hydrofluoric acid with a mass percentage of 40% is 150 g / L.

[0077] The urea content is 14g / L.

[0078] The content of octylphenol polyoxyethylene ether is 2.5 g / L.

[0079] The sodium dodecyl sulfate content is 0.25 g / L.

[0080] The SGCS content was 0.25 g / L.

[0081] The content of AHS-14 was 0.25 g / L.

[0082] The water content is 517.25 g / L.

[0083] The specific steps of chemical milling TA12A titanium alloy include the following:

[0084] Step S1: Clean and dry the workpiece; specifically, use hot alkali to remove surface dust and oil from the workpiece to be chemically milled, clean the workpiece with hot water and cold water respectively, then put the workpiece into an acid solution containing HF for pickling to obtain a smooth surface, then clean it with cold water and hot water at 70℃~80℃ respectively, and finally dry it.

[0085] Step S2: Coat the surface of the workpiece obtained in step S1 with a peelable protective coating. Allow the coating to dry and cure naturally into a film for 24 hours. Then, engrave the chemical milling pattern on the protective film and peel off the protective film from the chemical milling area.

[0086] Step S3: The workpiece obtained in Step S3 is then placed into the chemical milling solution for chemical milling. The temperature is controlled at 30℃±2℃, and the chemical milling time is 120 minutes. During the chemical milling process, the solution is thoroughly stirred to reduce the influence of concentration and temperature gradient, and to form a fine and dense foam layer on the solution surface to suppress acid mist escape. During chemical milling, a dense, layered white foam layer forms on the surface of the solution, and no acid mist odor can be detected near the edge of the chemical milling tank. The acid mist suppression rate is 93%.

[0087] Step S4: Once the chemical milling depth is reached, immediately remove the workpiece and thoroughly rinse off any residual chemical milling solution on the workpiece surface with warm water at 40℃~50℃. After drying, peel off all protective layers.

[0088] In this embodiment, the chemical milling depth was 3.498 mm, the chemical milling time was 120 min, the chemical milling speed was 29.15 μm / min, and the flatness was ±0.04 mm. The surface roughness of the workpiece was tested using a Surtronic electric profilometer. The surface roughness before chemical milling was 0.75 μm, and the surface roughness after chemical milling was 0.55 μm.

[0089] Example 4:

[0090] Composition of chemical milling solution:

[0091] The content of nitric acid with a mass percentage concentration of 65% is 325 g / L.

[0092] The concentration of hydrofluoric acid with a mass percentage of 40% is 150 g / L.

[0093] The urea content is 14g / L.

[0094] The sodium dodecyl sulfate content is 0.25 g / L.

[0095] The content of octylphenol polyoxyethylene ether is 2.5 g / L.

[0096] The SGCS content was 0.25 g / L.

[0097] The content of AHS-14 was 0.25 g / L.

[0098] The water content is 517.25 g / L.

[0099] The specific steps of chemical milling TC1 titanium alloy include the following:

[0100] Step S1: Clean and dry the workpiece; specifically, use hot alkali to remove surface dust and oil from the workpiece to be chemically milled, clean the workpiece with hot water and cold water respectively, then put the workpiece into an acid solution containing HF for pickling to obtain a smooth surface, then clean it with cold water and hot water at 70℃~80℃ respectively, and finally dry it.

[0101] Step S2: Coat the surface of the workpiece obtained in step S1 with a peelable protective coating. Allow the coating to dry and cure naturally into a film for 24 hours. Then, engrave the chemical milling pattern on the protective film and peel off the protective film from the chemical milling area.

[0102] Step S3: The workpiece obtained in Step S3 is then placed into the chemical milling solution for chemical milling. The temperature is controlled at 30℃±2℃, and the chemical milling time is 120 minutes. During the chemical milling process, the solution is thoroughly stirred to reduce the influence of concentration and temperature gradient, and to form a fine and dense foam layer on the solution surface to suppress acid mist escape. During chemical milling, a dense, layered white foam layer forms on the surface of the solution, and no acid mist odor can be detected near the edge of the chemical milling tank. The acid mist suppression rate is 94%.

[0103] Step S4: Once the chemical milling depth is reached, immediately remove the workpiece and thoroughly rinse off any residual chemical milling solution on the workpiece surface with warm water at 40℃~50℃. After drying, peel off all protective layers.

[0104] In this embodiment, the chemical milling depth was 3.411 mm, the chemical milling time was 120 min, the chemical milling speed was 28.43 μm / min, and the flatness was ±0.04 mm. The surface roughness of the workpiece was tested using a Surtronic electric profilometer. The surface roughness before chemical milling was 0.63 μm, and the surface roughness after chemical milling was 0.47 μm.

[0105] Hydrogen content in the titanium alloy samples of the four examples before and after chemical milling was measured using a hydrogen analyzer. The hydrogen permeation during chemical milling was found to be 2.5 ppm, 2.9 ppm, 2.8 ppm, and 2.9 ppm, respectively. No intergranular or end-grain corrosion was observed after chemical milling. No defects such as gas grooves, ripples, protrusions, or depressions were found in the deep-step chemical milling transition zone and fillets. The tensile and fatigue properties of the titanium alloys before and after chemical milling were tested according to GB / T228-2021 and GB3075-2021, respectively. The tensile strength of TC4 titanium alloy before chemical milling was 909 MPa, and after chemical milling, it was 906 MPa, with a yield strength of 891 MPa for both. The tensile strength of TC1 titanium alloy before chemical milling was 729 MPa, and after chemical milling, it was 726 MPa, with a yield strength of 596 MPa. The developed deep-step chemical milling process has a relatively small impact on the mechanical properties of the titanium alloys.

[0106] The above description is merely a preferred embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural transformations made using the contents of the present invention under the inventive concept of the present invention, or direct / indirect applications in other related technical fields, are included within the patent protection scope of the present invention.

Claims

1. A high-precision milling method for deep steps applicable to various types of titanium alloys, characterized in that, The deep step has a chemical milling depth ≥ 3 mm; the chemical milling solution used comprises nitric acid, hydrofluoric acid, urea, octylphenol polyoxyethylene ether, sodium dodecyl sulfate, glycosyl gemini cationic surfactant SGCS, aminosulfonate gemini surfactant AHS-14, and water; the content of each component is as follows: Nitric acid with a mass percentage concentration of 65% is 300~365 g / L; Hydrofluoric acid with a mass percentage concentration of 40% is 125~160 g / L; Urea: 12~15 g / L; Octylphenol polyoxyethylene ether: 2~3 g / L; Sodium dodecyl sulfate: 0.2~0.3 g / L; Glycosyl gemini cationic surfactant SGCS: 0.2~0.3 g / L; Aminosulfonate type gemini surfactant AHS-14: 0.2~0.3 g / L; Water: content ranges from 396.8 to 618.7 g / L; The method includes the following steps: Step S1: Clean and dry the workpiece; Step S2: Coat the workpiece surface obtained in step S1 with a peelable protective coating. Allow the coating to dry and cure naturally into a film for 24 hours. Then, engrave the chemical milling pattern on the protective film and peel off the protective film from the chemical milling area. Step S3: Place the workpiece obtained in step S3 into the chemical milling solution for chemical milling. Step S4: Once the chemical milling depth is reached, immediately remove the workpiece, clean off any residual chemical milling solution from the workpiece surface, and after drying, peel off all protective layers. Among them, the chemical milling quality meets the following requirements: chemical milling speed of 25~35μm / min per side, surface roughness Ra≤0.6μm, flatness ±0.05mm, and hydrogen absorption <3ppm.

2. The method for high-precision milling of deep steps applicable to various types of titanium alloys as described in claim 1, characterized in that, In step S1, hot alkali is used to remove surface dust and oil from the workpiece to be chemically milled. The workpiece is then cleaned with hot water and cold water respectively, and then placed in an acid solution containing HF for pickling to obtain a smooth surface. After that, it is cleaned with cold water and hot water at 70℃~80℃ respectively, and finally dried.

3. The method for high-precision milling of deep steps applicable to various types of titanium alloys as described in claim 1, characterized in that, In step S3, during chemical milling, the temperature is controlled at 25-35 ℃, and the chemical milling solution is thoroughly stirred during the process.

4. The method for high-precision milling of deep steps applicable to various types of titanium alloys as described in claim 1, characterized in that, In step S4, the residual chemical milling solution on the workpiece surface is thoroughly rinsed off with warm water at 40℃~50℃.