High-strength ultra-thin titanium alloy for motor clamping spring and preparation method thereof

Abstract

The application relates to the technical field of motor clamping springs, and particularly discloses a high-strength ultra-thin titanium alloy for motor clamping springs and a preparation method thereof. The titanium alloy ingot is first subjected to hot forging processing, and then is subjected to hot rolling after the coarse grains are broken. In the hot rolling process, pulse current is adopted to obtain finer and more uniform grain structures than traditional hot rolling through the electroplastic effect. After that, the titanium alloy substrate surface is subjected to shot blasting treatment and carbonitriding treatment to enhance the hardness, strength, wear resistance and fatigue resistance of the material. Finally, a thermal auxiliary ultrasonic rolling process is adopted to eliminate surface defects, increase the surface density, introduce a residual compressive stress field, inhibit the initiation and expansion of fatigue microcracks, and enhance the fatigue resistance of the material.

Description

Technical Field

[0001] This invention relates to the field of motor retainer technology, specifically to a high-strength ultra-thin titanium alloy for motor retainers and its preparation method. Background Technology

[0002] A motor retainer is a mechanical fastener installed in the groove or hole of a motor shaft to fix bearings, gears, and other mechanical parts, preventing axial movement of these parts on the motor shaft and ensuring the stability and safety of the motor during operation.

[0003] Traditional motor retainers are typically made of spring steel or stainless steel. The high density of steel is unsuitable for the lightweight and miniaturized motors required in high-end equipment. In certain special operating conditions, the thickness of the motor retainer cannot be too thick; thin steel retainers cannot withstand high loads and are prone to deformation or breakage, affecting the stability and normal operation of the motor. Compared to stainless steel, titanium alloys have a lower density, requiring less and thinner materials for the same strength requirements, thus meeting the needs of lightweight and miniaturized motors. Titanium alloys also exhibit superior resistance to alternating stress, resulting in a longer fatigue life in the same working environment. Furthermore, titanium alloys possess good corrosion resistance and a wider operating temperature range. Therefore, providing a high-strength, ultra-thin titanium alloy for motor retainers is crucial for promoting the development of motor retainers and motors towards high-end and intelligent designs. Summary of the Invention

[0004] The purpose of this invention is to provide a high-strength ultra-thin titanium alloy for motor retaining rings and its preparation method, which combines the advantages of high strength and thin volume, and solves the problems of low strength and insufficient fatigue life of thin motor retaining rings.

[0005] To solve the above-mentioned technical problems, the present invention provides the following technical solution:

[0006] A method for preparing a high-strength ultra-thin titanium alloy motor retainer ring, specifically comprising:

[0007] Step 1: After hot forging and processing of titanium alloy ingots, solution treatment is performed to obtain heat-treated titanium alloy billets.

[0008] Step 2: The heat-treated titanium alloy billet is hot-rolled using a pulsed current assisted hot rolling process, followed by aging treatment to obtain an ultra-thin titanium alloy matrix.

[0009] Step 3: Shot peening and carbonitriding are performed on the ultrathin titanium alloy substrate to obtain a surface-strengthened ultrathin titanium alloy.

[0010] Step 4: The surface-strengthened ultrathin titanium alloy is subjected to heat-assisted ultrasonic rolling treatment to obtain a high-strength ultrathin titanium alloy for motor retaining rings.

[0011] As a limitation of the present invention, the hot forging process includes a first hot forging process and a second hot forging process. The process parameters for the first hot forging process include: a first hot forging temperature of 1150-1170℃, a holding time of 2-4h, and a total deformation of 70-80%. The process parameters for the second hot forging process include: a second hot forging temperature of 940-960℃, a holding time of 1-3h, and a total deformation of 60-70%.

[0012] As a limitation of the present invention, the process parameters of the solution treatment include: a solution temperature of 950-970℃, a holding time of 0.5-1h, and quenching with quenching oil at 80-100℃ after the holding time is completed.

[0013] First, heat the TC4 titanium alloy ingot to the β phase transformation temperature (T). β The TC4 titanium alloy ingot is heated to approximately 980℃ and held at that temperature. During this holding process, the ingot is entirely in the β phase region. The coarse columnar crystals and grain boundary α phase contained in the ingot structure completely dissolve and transform into a single β phase with uniform composition. Through hot forging deformation, the residual dendrites and original grain boundaries in the ingot structure are completely broken and dynamically recrystallized to form fine equiaxed β grains. This eliminates defects such as loose structure and porosity inside the ingot, improves the density of the material, and lays the foundation for subsequent processing. Subsequently, the temperature is lowered to below the β phase transformation temperature and held at that temperature. During this holding process, a primary α phase with higher hardness precipitates in the β phase of the ingot structure. During hot forging, the softer β phase deforms, while the hard α grains hinder grain boundary movement and simultaneously rotate, break, and spheroidize. During the deformation process, both the α and β phases are refined, forming a more uniform β phase. The addition of a uniform and fine equiaxed α+β phase structure improves the anisotropy of the material, resulting in a more homogeneous composition and enhanced processing performance. During ultra-thin rolling, it exhibits excellent plastic deformation capacity, achieving large deformations without cracking and avoiding plate defects (wavy, warped, etc.) caused by uneven microstructure during rolling. After hot forging, heating to the α+β two-phase region temperature causes the β phase to decompose, and its constituent elements (such as β-phase stabilizing elements like V) diffuse into the α phase, reducing the β phase content and increasing the α phase content. After heat treatment, quenching with quenching oil is used to suppress the precipitation of coarse secondary α phases, thereby obtaining a metastable β phase matrix in solid solution containing the primary α phase. The fine grains enhance the strength and toughness of the material through the grain refinement strengthening effect, while simultaneously hindering the initiation and propagation of fatigue microcracks, thus improving the material's fatigue resistance.

[0014] As a limitation of the present invention, the hot rolling process uses pulsed current assisted hot rolling, and the process parameters include: hot rolling temperature of 850-870℃, rolling passes of 8-10, and total rolling amount of 80-90%; during the hot rolling process, the pulsed current is initially 1.0-1.2Hz, and decreases linearly to 0.1-0.3Hz with the increase of the number of passes, and the duty cycle is initially 30-40%, and decreases linearly to 10-20% with the increase of the number of passes.

[0015] As a limitation of the present invention, the aging process is specifically a dual aging process. During the first aging process, the process parameters include: the first aging temperature is 480-500℃ and the holding time is 4-5h; during the second aging process, the process parameters include: the second aging temperature is 550-570℃ and the holding time is 2-3h.

[0016] Pulsed current-assisted hot rolling is employed. Under the influence of high temperature and rolling force, the original equiaxed grains deform. Simultaneously, the pulsed current, through the electroplastic effect, reduces the resistance to dislocation movement while promoting atomic diffusion, accelerating the dynamic recovery and recrystallization process. This results in finer grains forming at the grain boundaries of the deformed grains. During hot rolling, the hard α phase is more easily broken and spheroidized, while the soft β phase is more easily flowed and recrystallized, resulting in a finer and more uniform grain structure than traditional hot rolling, thus improving the material's strength, toughness, and other properties. A double aging treatment is then applied after rolling. During the first aging process, fine secondary α phases are dispersed and precipitated in the metastable β phase matrix. During the second aging process, the precipitates undergo Ostwald ripening, dissolving the fine precipitates and allowing larger precipitates to grow, resulting in more uniform precipitate sizes. Through aging treatment, internal stress is relaxed, defects such as dislocations in the matrix are repaired, and the precipitation of fine secondary α phases enhances the material's strength, hardness, and other properties through precipitation strengthening.

[0017] As a limitation of the present invention, the shot peening treatment specifically refers to:

[0018] The ultrathin titanium alloy substrate is placed in a shot peening device, and shot is applied vertically to the surface of the ultrathin titanium alloy substrate at an incident angle of 90°. The shot used is either cast steel shot or silicon nitride ceramic shot, with a shot diameter of 0.5-1.0 mm, a shot intensity of 0.35-0.45 mmN, and a coverage of 150-200%. After shot peening, the substrate is cleaned, ultrasonically cleaned in anhydrous ethanol for 5-10 minutes, and vacuum dried at 80-90℃ for 20-30 minutes to complete the shot peening treatment.

[0019] Shot peening is performed on ultrathin titanium alloy substrates. During shot peening, the surface layer of the substrate is subjected to stress from the shot peening, causing plastic deformation of the surface grains, increasing the dislocation density, forming a dislocation cell structure, which further evolves into subgrain boundaries and ultrafine grains, forming a fine grain layer, thereby improving the surface hardness, wear resistance and fatigue resistance.

[0020] As a limitation of the present invention, the carbonitriding treatment specifically refers to:

[0021] After shot peening and cleaning of the ultra-thin titanium alloy substrate, it is transferred to a dual-glow plasma metallization system and vacuumed to 1×10⁻⁶. -3 -5×10 -3 Pa, the substrate is preheated to 500-520℃, and argon gas is introduced for plasma cleaning. The argon gas flow rate is set to 180-200 sccm and the cleaning time is 10-15 min. After cleaning, a mixture of nitrogen, acetylene and hydrogen gas is introduced for carbonitriding treatment. After co-diffusion, the furnace is cooled to room temperature to obtain a surface-strengthened ultrathin titanium alloy.

[0022] As a limitation of the present invention, the process parameters of the carbonitriding treatment include: nitrogen flow rate of 150-170 sccm, acetylene flow rate of 20-30 sccm, hydrogen flow rate of 100-130 sccm, cathode voltage of 500-520V, and co-infiltration time of 2-4h.

[0023] Under the action of cathode voltage, hydrogen gas acts as a reducing agent to reduce the thin oxide layer on the surface of titanium alloy, exposing fresh Ti atoms that react with active N and C atoms. Nitrogen gas and acetylene ionize to generate active carbon atoms, and carbon atoms react with titanium alloy to generate fine TiN, TiC, and TiCN, forming a dispersed strengthening layer inside the titanium alloy matrix, which enhances the material's strength, hardness, wear resistance, and other properties.

[0024] As a limitation of the present invention, the process parameters of the heat-assisted ultrasonic rolling include: substrate temperature of 200-220℃, static pressure of 200-300N, amplitude of 10-20μm, frequency of 20-30kHz, feed speed of 200-300mm / min, and rolling times of 2-3 times.

[0025] Surface-strengthened ultrathin titanium alloys are treated using a heat-assisted ultrasonic rolling process. During ultrasonic treatment, under static pressure and high-frequency impact, the material surface undergoes plastic flow, smoothing the high-roughness surface layer formed by shot peening and carbonitriding, thus reducing the surface roughness of the material. At the same time, the fine grains of the surface layer are further processed, further reducing the grain size and improving the density and wear resistance of the material surface. In addition, a residual compressive stress field is formed inside the surface layer to counteract the alternating tensile stress during the use of the material, inhibiting the initiation and development of fatigue microcracks and improving the fatigue resistance of the material.

[0026] A high-strength, ultra-thin titanium alloy for motor retaining rings is prepared using any of the preparation methods described above.

[0027] Compared with the prior art, the beneficial effects of the present invention are:

[0028] This invention employs pulsed current-assisted hot rolling, which reduces dislocation movement resistance through electroplasticity while promoting atomic diffusion, accelerating the dynamic recovery and recrystallization process, and obtaining a finer and more uniform grain structure than traditional hot rolling, thereby improving the strength, toughness and other properties of the material.

[0029] This invention employs a solution treatment and dual aging treatment to suppress the precipitation of coarse secondary α phase, thereby obtaining a metastable β phase matrix in a solid solution state containing the primary α phase. The fine grains enhance the strength and toughness of the material through the grain refinement strengthening effect and precipitation strengthening effect, while hindering the initiation and propagation of fatigue microcracks and improving the fatigue resistance of the material.

[0030] This invention involves shot peening and carbonitriding of an ultrathin titanium alloy substrate to improve the surface hardness, wear resistance, and fatigue resistance. Subsequently, a heat-assisted ultrasonic rolling process is used to further refine the surface grains of the ultrathin titanium alloy, enhancing the surface density and wear resistance. Simultaneously, a residual compressive stress field is formed below the surface to counteract the alternating tensile stress during use, inhibiting the initiation and development of fatigue microcracks and improving the material's fatigue resistance. Detailed Implementation

[0031] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. The terminology used in the embodiments is for describing specific implementation schemes, not for limiting the scope of protection of the present invention. The dosages in the embodiments are laboratory-scale tests and can be scaled up proportionally. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0032] Titanium alloy ingot (grade: TC4 titanium alloy, diameter: 200mm, composition: Al: 6.10wt%, V: 3.40wt%, Fe: 0.32wt%, O: 0.21wt%, C: 0.10wt%, Si: 0.07wt%, N: 0.05wt%, balance Ti), boron sputtering target (purity: 99.99%), aluminum sputtering target (purity: 99.99%).

[0033] Example 1: A method for preparing a high-strength ultra-thin titanium alloy motor retainer, specifically as follows:

[0034] Step 1: The TC4 titanium alloy ingot is machined by turning to remove the oxide layer on the surface. It is then transferred to a heating furnace and heated to 1150℃ for 2 hours. After holding, it undergoes a first hot forging process with a total deformation of 70%. It is then placed back into the heating furnace and heated to 940℃ for 1 hour. After holding, it undergoes a second hot forging process with a total deformation of 60%, resulting in a titanium alloy billet. The titanium alloy billet is then solution treated by heating it to 950℃ and holding it for 0.5 hours. After holding, it is quenched in 80℃ quenching oil to obtain a heat-treated titanium alloy billet.

[0035] Step 2: Place the heat-treated titanium alloy billet into the rolling mill and perform pulse current assisted hot rolling. Heat the heat-treated titanium alloy billet to 850℃ and hot roll it. Set the rolling passes to 10 passes. The pulse current is initially 1.0Hz and decreases linearly to 0.1Hz with the increase of the number of passes. The duty cycle is initially 30% and decreases linearly to 10% with the increase of the number of passes. The total rolling amount is 80%. After hot rolling, perform double aging treatment. Transfer the hot-rolled billet to a heating furnace and hold it at 480℃ for 4 hours. After air cooling to room temperature, hold it at 550℃ for 2 hours and air cool to room temperature to obtain an ultra-thin titanium alloy matrix.

[0036] Step 3: Shot peening and carbonitriding treatment of the ultra-thin titanium alloy substrate. The ultra-thin titanium alloy substrate is placed in a shot peening apparatus and shot peening is performed using 0.5mm diameter cast steel shot. The shot incident angle is 90° perpendicular to the surface of the ultra-thin titanium alloy substrate. The shot peening intensity is set to 0.35mmN, and the coverage is 200%. After shot peening, the substrate is cleaned, ultrasonically cleaned in anhydrous ethanol for 5 minutes, and vacuum dried at 80℃ for 30 minutes. After cleaning, it is transferred to a double-glow plasma infiltration apparatus for carbonitriding treatment, with a vacuum of 5×10⁻⁶. -3 Pa, the substrate is preheated to 500℃, and argon gas is introduced for plasma cleaning. The argon gas flow rate is set to 200 sccm and the cleaning time is 15 min. After cleaning, a mixture of nitrogen, acetylene and hydrogen gas is introduced. The nitrogen gas flow rate is set to 150 sccm, the acetylene gas flow rate is set to 20 sccm, and the hydrogen gas flow rate is set to 130 sccm. The cathode voltage is 500V and the co-diffusion time is 3 h. After co-diffusion, the furnace is cooled to room temperature to obtain a surface-strengthened ultrathin titanium alloy.

[0037] Step 4: Heat-assisted ultrasonic rolling treatment of surface-strengthened ultrathin titanium alloy. The surface-strengthened ultrathin titanium alloy is placed in a vacuum rolling equipment. The substrate is preheated to 200℃ for ultrasonic rolling. The static pressure is set to 200N, the amplitude is 10μm, the frequency is 20kHz, the feed speed is 200mm / min, and the rolling is performed twice. After rolling, the substrate is cooled to room temperature to obtain a high-strength ultrathin titanium alloy for motor retaining rings.

[0038] Example 2: A method for preparing a high-strength ultra-thin titanium alloy motor retainer, specifically as follows:

[0039] Step 1: The TC4 titanium alloy ingot is machined by turning to remove the oxide layer on the surface. It is then transferred to a heating furnace and heated to 1155℃ for 2 hours. After holding, it undergoes a first hot forging process with a total deformation of 70%. It is then placed back into the heating furnace and heated to 945℃ for 1 hour. After holding, it undergoes a second hot forging process with a total deformation of 60%, resulting in a titanium alloy billet. The titanium alloy billet is then solution treated by heating it to 955℃ and holding it for 0.5 hours. After holding, it is quenched in 80℃ quenching oil to obtain a heat-treated titanium alloy billet.

[0040] Step 2: Place the heat-treated titanium alloy billet into the rolling mill and perform pulse current assisted hot rolling. Heat the heat-treated titanium alloy billet to 855℃ and hot roll it. Set the rolling passes to 10 passes. The pulse current is initially 1.1Hz and decreases linearly to 0.2Hz with the increase of passes. The duty cycle is initially 30% and decreases linearly to 10% with the increase of passes. The total rolling amount is 80%. After hot rolling, perform double aging treatment. Transfer the hot-rolled billet to a heating furnace and hold it at 485℃ for 4 hours. After air cooling to room temperature, hold it at 555℃ for 2 hours and air cool to room temperature to obtain an ultra-thin titanium alloy matrix.

[0041] Step 3: Shot peening and carbonitriding treatment of the ultra-thin titanium alloy substrate. The ultra-thin titanium alloy substrate is placed in a shot peening apparatus and shot peening is performed using 0.5mm diameter cast steel shot. The shot incident angle is 90° perpendicular to the surface of the ultra-thin titanium alloy substrate. The shot peening intensity is set to 0.4mmN, and the coverage is 200%. After shot peening, the substrate is cleaned, ultrasonically cleaned in anhydrous ethanol for 5 minutes, and vacuum dried at 80℃ for 30 minutes. After cleaning, it is transferred to a double-glow plasma infiltration apparatus for carbonitriding treatment, with a vacuum of 5×10⁻⁶. -3 Pa, the substrate is preheated to 500℃, and argon gas is introduced for plasma cleaning. The argon gas flow rate is set to 200 sccm and the cleaning time is 15 min. After cleaning, a mixture of nitrogen, acetylene and hydrogen gas is introduced. The nitrogen gas flow rate is set to 160 sccm, the acetylene gas flow rate is set to 25 sccm, and the hydrogen gas flow rate is set to 115 sccm. The cathode voltage is 510 V and the co-diffusion time is 3 h. After co-diffusion, the furnace is cooled to room temperature to obtain a surface-strengthened ultrathin titanium alloy.

[0042] Step 4: Heat-assisted ultrasonic rolling treatment of surface-strengthened ultrathin titanium alloy. The surface-strengthened ultrathin titanium alloy is placed in a vacuum rolling equipment. The substrate is preheated to 200℃ for ultrasonic rolling. The static pressure is set to 220N, the amplitude is 10μm, the frequency is 20kHz, the feed speed is 200mm / min, and the rolling is performed twice. After rolling, the substrate is cooled to room temperature to obtain a high-strength ultrathin titanium alloy for motor retaining rings.

[0043] Example 3: A method for preparing a high-strength ultra-thin titanium alloy motor retainer, specifically as follows:

[0044] Step 1: The TC4 titanium alloy ingot is machined by turning to remove the oxide layer on the surface. It is then transferred to a heating furnace and heated to 1160℃ for 2 hours. After holding, it undergoes a first hot forging process with a total deformation of 70%. It is then placed back into the heating furnace and heated to 950℃ for 1 hour. After holding, it undergoes a second hot forging process with a total deformation of 60%, resulting in a titanium alloy billet. The titanium alloy billet is then solution treated by heating it to 960℃ and holding it for 0.5 hours. After holding, it is quenched in 80℃ quenching oil to obtain a heat-treated titanium alloy billet.

[0045] Step 2: Place the heat-treated titanium alloy billet into the rolling mill and perform pulse current assisted hot rolling. Heat the heat-treated titanium alloy billet to 860℃ and hot roll it. Set the rolling passes to 10 passes. The pulse current is initially 1.2Hz and decreases linearly to 0.3Hz with the increase of the number of passes. The duty cycle is initially 30% and decreases linearly to 10% with the increase of the number of passes. The total rolling amount is 80%. After hot rolling, perform double aging treatment. Transfer the hot-rolled billet to a heating furnace and hold it at 490℃ for 4 hours. After air cooling to room temperature, hold it at 560℃ for 2 hours and air cool to room temperature to obtain an ultra-thin titanium alloy matrix.

[0046] Step 3: Shot peening and carbonitriding treatment of the ultra-thin titanium alloy substrate. The ultra-thin titanium alloy substrate is placed in a shot peening apparatus and shot peening is performed using 0.5mm diameter cast steel shot. The shot incident angle is 90° perpendicular to the surface of the ultra-thin titanium alloy substrate. The shot peening intensity is set to 0.45mmN, and the coverage is 200%. After shot peening, the substrate is cleaned, ultrasonically cleaned in anhydrous ethanol for 5 minutes, and vacuum dried at 80℃ for 30 minutes. After cleaning, it is transferred to a double-glow plasma infiltration apparatus for carbonitriding treatment, with a vacuum of 5×10⁻⁶. -3Pa, the substrate is preheated to 500℃, and argon gas is introduced for plasma cleaning. The argon gas flow rate is set to 200 sccm and the cleaning time is 15 min. After cleaning, a mixture of nitrogen, acetylene and hydrogen gas is introduced. The nitrogen gas flow rate is set to 170 sccm, the acetylene gas flow rate is set to 30 sccm, the hydrogen gas flow rate is set to 100 sccm, the cathode voltage is set to 520V, and the co-diffusion time is 3 h. After co-diffusion, the furnace is cooled to room temperature to obtain a surface-strengthened ultrathin titanium alloy.

[0047] Step 4: Heat-assisted ultrasonic rolling treatment of surface-strengthened ultrathin titanium alloy. The surface-strengthened ultrathin titanium alloy is placed in a vacuum rolling equipment. The substrate is preheated to 200℃ for ultrasonic rolling. The static pressure is set to 250N, the amplitude is 10μm, the frequency is 20kHz, the feed speed is 200mm / min, and the rolling is performed twice. After rolling, the substrate is cooled to room temperature to obtain a high-strength ultrathin titanium alloy for motor retaining rings.

[0048] Based on Example 1, the following comparative experiments were conducted, specifically Comparative Example 1, Comparative Example 2, and Comparative Example 3, as described below:

[0049] Comparative Example 1: This comparative example relates to a method for preparing a high-strength ultra-thin titanium alloy for motor retaining rings. The difference from Example 1 is that pulsed current assistance was not used during hot rolling. Specifically:

[0050] Step 1: The TC4 titanium alloy ingot is machined by turning to remove the oxide layer on the surface. It is then transferred to a heating furnace and heated to 1150℃ for 2 hours. After holding, it undergoes a first hot forging process with a total deformation of 70%. It is then placed back into the heating furnace and heated to 940℃ for 1 hour. After holding, it undergoes a second hot forging process with a total deformation of 60%, resulting in a titanium alloy billet. The titanium alloy billet is then solution treated by heating it to 950℃ and holding it for 0.5 hours. After holding, it is quenched in 80℃ quenching oil to obtain a heat-treated titanium alloy billet.

[0051] Step 2: Place the heat-treated titanium alloy billet into the rolling mill for hot rolling. Heat the heat-treated titanium alloy billet to 850℃ for hot rolling, set the rolling passes to 10, and the total rolling amount to 80%. After hot rolling, perform double aging treatment. Transfer the hot-rolled billet to a heating furnace, hold it at 480℃ for 4 hours, air cool it to room temperature, hold it at 550℃ for 2 hours, and air cool it to room temperature to obtain an ultra-thin titanium alloy matrix.

[0052] Step 3: Shot peening and carbonitriding treatment of the ultra-thin titanium alloy substrate. The ultra-thin titanium alloy substrate is placed in a shot peening apparatus and shot peening is performed using 0.5mm diameter cast steel shot. The shot incident angle is 90° perpendicular to the surface of the ultra-thin titanium alloy substrate. The shot peening intensity is set to 0.35mmN, and the coverage is 200%. After shot peening, the substrate is cleaned, ultrasonically cleaned in anhydrous ethanol for 5 minutes, and vacuum dried at 80℃ for 30 minutes. After cleaning, it is transferred to a double-glow plasma infiltration apparatus for carbonitriding treatment, with a vacuum of 5×10⁻⁶. -3 Pa, the substrate is preheated to 500℃, and argon gas is introduced for plasma cleaning. The argon gas flow rate is set to 200 sccm and the cleaning time is 15 min. After cleaning, a mixture of nitrogen, acetylene and hydrogen gas is introduced. The nitrogen gas flow rate is set to 150 sccm, the acetylene gas flow rate is set to 20 sccm, and the hydrogen gas flow rate is set to 130 sccm. The cathode voltage is 500V and the co-diffusion time is 3 h. After co-diffusion, the furnace is cooled to room temperature to obtain a surface-strengthened ultrathin titanium alloy.

[0053] Step 4: Heat-assisted ultrasonic rolling treatment of surface-strengthened ultrathin titanium alloy. The surface-strengthened ultrathin titanium alloy is placed in a vacuum rolling equipment. The substrate is preheated to 200℃ for ultrasonic rolling. The static pressure is set to 200N, the amplitude is 10μm, the frequency is 20kHz, the feed speed is 200mm / min, and the rolling is performed twice. After rolling, the substrate is cooled to room temperature to obtain a high-strength ultrathin titanium alloy for motor retaining rings.

[0054] Comparative Example 2: This comparative example relates to a method for preparing a high-strength ultra-thin titanium alloy motor retainer, which differs from Example 1 in that it does not undergo heat-assisted ultrasonic rolling treatment. Specifically:

[0055] Step 1: The TC4 titanium alloy ingot is machined by turning to remove the oxide layer on the surface. It is then transferred to a heating furnace and heated to 1150℃ for 2 hours. After holding, it undergoes a first hot forging process with a total deformation of 70%. It is then placed back into the heating furnace and heated to 940℃ for 1 hour. After holding, it undergoes a second hot forging process with a total deformation of 60%, resulting in a titanium alloy billet. The titanium alloy billet is then solution treated by heating it to 950℃ and holding it for 0.5 hours. After holding, it is quenched in 80℃ quenching oil to obtain a heat-treated titanium alloy billet.

[0056] Step 2: Place the heat-treated titanium alloy billet into the rolling mill and perform pulse current assisted hot rolling. Heat the heat-treated titanium alloy billet to 850℃ and hot roll it. Set the rolling passes to 10 passes. The pulse current is initially 1.0Hz and decreases linearly to 0.1Hz with the increase of the number of passes. The duty cycle is initially 30% and decreases linearly to 10% with the increase of the number of passes. The total rolling amount is 80%. After hot rolling, perform double aging treatment. Transfer the hot-rolled billet to a heating furnace and hold it at 480℃ for 4 hours. After air cooling to room temperature, hold it at 550℃ for 2 hours and air cool to room temperature to obtain an ultra-thin titanium alloy matrix.

[0057] Step 3: Shot peening and carbonitriding treatment of the ultra-thin titanium alloy substrate. The ultra-thin titanium alloy substrate is placed in a shot peening apparatus and shot peening is performed using 0.5mm diameter cast steel shot. The shot incident angle is 90° perpendicular to the surface of the ultra-thin titanium alloy substrate. The shot peening intensity is set to 0.35mmN, and the coverage is 200%. After shot peening, the substrate is cleaned, ultrasonically cleaned in anhydrous ethanol for 5 minutes, and vacuum dried at 80℃ for 30 minutes. After cleaning, it is transferred to a double-glow plasma infiltration apparatus for carbonitriding treatment, with a vacuum of 5×10⁻⁶. -3 Pa, the substrate is preheated to 500℃, and argon gas is introduced for plasma cleaning. The argon gas flow rate is set to 200 sccm, and the cleaning time is 15 min. After cleaning, a mixture of nitrogen, acetylene and hydrogen gas is introduced. The nitrogen gas flow rate is set to 150 sccm, the acetylene gas flow rate to 20 sccm, and the hydrogen gas flow rate to 130 sccm. The cathode voltage is 500V, and the co-diffusion time is 3 h. After co-diffusion, the furnace is cooled to room temperature to obtain a high-strength ultra-thin titanium alloy for motor snap rings.

[0058] Comparative Example 3: This comparative example relates to a method for preparing a high-strength ultra-thin titanium alloy for motor retaining rings. The difference from Example 1 is that carbonitriding treatment was not performed. Specifically:

[0059] Step 1: The TC4 titanium alloy ingot is machined by turning to remove the oxide layer on the surface. It is then transferred to a heating furnace and heated to 1150℃ for 2 hours. After holding, it undergoes a first hot forging process with a total deformation of 70%. It is then placed back into the heating furnace and heated to 940℃ for 1 hour. After holding, it undergoes a second hot forging process with a total deformation of 60%, resulting in a titanium alloy billet. The titanium alloy billet is then solution treated by heating it to 950℃ and holding it for 0.5 hours. After holding, it is quenched in 80℃ quenching oil to obtain a heat-treated titanium alloy billet.

[0060] Step 2: Place the heat-treated titanium alloy billet into the rolling mill and perform pulse current assisted hot rolling. Heat the heat-treated titanium alloy billet to 850℃ and hot roll it. Set the rolling passes to 10 passes. The pulse current is initially 1.0Hz and decreases linearly to 0.1Hz with the increase of the number of passes. The duty cycle is initially 30% and decreases linearly to 10% with the increase of the number of passes. The total rolling amount is 80%. After hot rolling, perform double aging treatment. Transfer the hot-rolled billet to a heating furnace and hold it at 480℃ for 4 hours. After air cooling to room temperature, hold it at 550℃ for 2 hours and air cool to room temperature to obtain an ultra-thin titanium alloy matrix.

[0061] Step 3: Shot peening and carbonitriding treatment of the ultrathin titanium alloy substrate. The ultrathin titanium alloy substrate is placed in the shot peening equipment and shot peening is performed using cast steel shot with a diameter of 0.5 mm. The shot peening incident angle is 90° perpendicular to the surface of the ultrathin titanium alloy substrate. The shot peening intensity is set to 0.35 mmN and the coverage is 200%. After shot peening, the substrate is cleaned, ultrasonically cleaned in anhydrous ethanol for 5 min, and vacuum dried at 80℃ for 30 min. After cleaning, the surface-strengthened ultrathin titanium alloy is obtained.

[0062] Step 4: Heat-assisted ultrasonic rolling treatment of surface-strengthened ultrathin titanium alloy. The surface-strengthened ultrathin titanium alloy is placed in a vacuum rolling equipment. The substrate is preheated to 200℃ for ultrasonic rolling. The static pressure is set to 200N, the amplitude is 10μm, the frequency is 20kHz, the feed speed is 200mm / min, and the rolling is performed twice. After rolling, the substrate is cooled to room temperature to obtain a high-strength ultrathin titanium alloy for motor retaining rings.

[0063] Testing Experiments: High-strength ultra-thin titanium alloy motor retaining rings were prepared according to the preparation methods of each embodiment and comparative example, and used as test samples for tensile performance testing, impact performance testing, surface hardness testing, and fatigue performance testing. Specifically, the tensile performance test was conducted according to "Metallic Materials - Tensile Testing - Part 1: Room Temperature Test Method" (GB / T 228.1-2021), testing tensile strength; the impact performance test was conducted according to "Metallic Materials - Charpy Pendulum Impact Test Method" (GB / T 229-2020), testing impact strength; the surface hardness test was conducted according to "Metallic Materials - Vickers Hardness Test - Part 1: Test Method" (GB / T 4340.1-2024), testing Vickers hardness; and the fatigue performance test was conducted according to "Metallic Materials - Fatigue Testing - Axial Force Control Method" (GB / T 3075-2021), testing fatigue strength.

[0064]

[0065] Conclusion: The test data shows that the high-strength ultra-thin titanium alloy test samples of motor retainers prepared in each embodiment have higher tensile strength, impact strength, surface hardness and fatigue strength than the comparative example. The high-strength ultra-thin titanium alloy of motor retainers improved by the present invention has good tensile properties, impact properties, surface hardness and fatigue resistance, and has the advantages of high strength and thin volume, solving the problems of low strength and insufficient fatigue life of thin motor retainers.

[0066] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, it is intended that all variations falling within the meaning and scope of equivalents of the claims be included within the present invention.

Claims

1. A method for preparing a high-strength ultra-thin titanium alloy motor retainer, characterized in that: Specifically: Step 1: After hot forging and processing of titanium alloy ingots, solution treatment is performed to obtain heat-treated titanium alloy billets. Step 2: The heat-treated titanium alloy billet is hot-rolled using a pulsed current assisted hot rolling process, followed by aging treatment to obtain an ultra-thin titanium alloy matrix. Step 3: Shot peening and carbonitriding are performed on the ultrathin titanium alloy substrate to obtain a surface-strengthened ultrathin titanium alloy. Step 4: The surface-strengthened ultrathin titanium alloy is subjected to heat-assisted ultrasonic rolling treatment to obtain a high-strength ultrathin titanium alloy motor retainer. The hot forging process includes primary hot forging and secondary hot forging. The process parameters for primary hot forging are: primary hot forging temperature of 1150-1170℃, holding time of 2-4h, and total deformation of 70-80%. The process parameters for secondary hot forging are: secondary hot forging temperature of 940-960℃, holding time of 1-3h, and total deformation of 60-70%. The process parameters for solution treatment include: solution temperature of 950-970℃, holding time of 0.5-1h, and quenching with quenching oil at 80-100℃ after holding. During hot rolling, pulsed current is used to assist the hot rolling process. The process parameters include: hot rolling temperature of 850-870℃, 8-10 rolling passes, and total rolling weight of 80-90%. During the hot rolling process, the pulsed current is initially 1.0-1.2Hz, and decreases linearly to 0.1-0.3Hz with the increase of the number of passes. The duty cycle is initially 30-40%, and decreases linearly to 10-20% with the increase of the number of passes. The aging process specifically involves a dual aging process. For the first aging process, the process parameters include: an initial aging temperature of 480-500℃ and a holding time of 4-5 hours. For the second aging process, the process parameters include: a second aging temperature of 550-570℃ and a holding time of 2-3 hours. The process parameters for heat-assisted ultrasonic rolling include: substrate temperature of 200-220℃, static pressure of 200-300N, amplitude of 10-20μm, frequency of 20-30kHz, feed speed of 200-300mm / min, and rolling cycles of 2-3 times.

2. The method for preparing a high-strength ultra-thin titanium alloy motor retainer according to claim 1, characterized in that: The shot peening process specifically involves: The ultrathin titanium alloy substrate is placed in a shot peening device, and shot is applied vertically to the surface of the ultrathin titanium alloy substrate at an incident angle of 90°. The shot used is either cast steel shot or silicon nitride ceramic shot, with a shot diameter of 0.5-1.0 mm, a shot intensity of 0.35-0.45 mmN, and a coverage of 150-200%. After shot peening, the substrate is cleaned, ultrasonically cleaned in anhydrous ethanol for 5-10 minutes, and vacuum dried at 80-90℃ for 20-30 minutes to complete the shot peening treatment.

3. The method for preparing a high-strength ultra-thin titanium alloy motor retainer according to claim 1, characterized in that: The carbonitriding treatment specifically involves: After shot peening and cleaning of the ultra-thin titanium alloy substrate, it is transferred to a dual-glow plasma metallization system and vacuumed to 1×10⁻⁶. -3 -5×10 -3 Pa, the substrate is preheated to 500-520℃, and argon gas is introduced for plasma cleaning. The argon gas flow rate is set to 180-200 sccm and the cleaning time is 10-15 min. After cleaning, a mixture of nitrogen, acetylene and hydrogen gas is introduced for carbonitriding treatment. After co-diffusion, the furnace is cooled to room temperature to obtain a surface-strengthened ultrathin titanium alloy.

4. The method for preparing a high-strength ultra-thin titanium alloy motor retainer according to claim 3, characterized in that: The process parameters for carbonitriding include: nitrogen flow rate of 150-170 sccm, acetylene flow rate of 20-30 sccm, hydrogen flow rate of 100-130 sccm, cathode voltage of 500-520V, and co-infiltration time of 2-4h.

5. A high-strength, ultra-thin titanium alloy motor retaining ring, characterized in that: It is prepared by the preparation method according to any one of claims 1-4.

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