A hydrogen charging process for titanium alloys

Abstract

This invention provides a hydrogen treatment process for titanium alloys, comprising: (1) placing the titanium alloy into a vacuum furnace after shot peening and pickling; (2) calculating the mass m of TiH2 powder, and weighing a mass greater than m of TiH2 powder using an electronic balance and placing it into the vacuum furnace; wherein m = 2.22 × 10⁻⁶. ‑3 ×μ×(V1+V2), where μ is the ratio of the volume of hydrogen gas replaced per unit volume to the volume of the titanium alloy; V1 is the volume of the titanium alloy; V2 is the volume of the vacuum furnace cavity; (3) Heat to the hydrogen placement temperature, then maintain the temperature and pressure, and finally cool to room temperature. In this invention, the hydrogen gas released by the high-temperature reaction of TiH2 powder is used as the hydrogen source for the hydrogen placement of titanium alloy. TiH2 powder has stable performance at room temperature and is easy to store and transport. The pure titanium produced by the reaction is hydrogenated at high temperature to produce TiH2 powder, which can be recycled.

Description

Technical Field

[0001] This invention relates to the field of hydrogen removal technology for titanium alloys, and more specifically to a process for hydrogen removal treatment of titanium alloys. Background Technology

[0002] Titanium alloys have excellent performance characteristics, but their low room temperature plasticity, high deformation resistance, and easy springback mean that most titanium alloys must be plastically deformed at high temperatures. Hot working often results in problems such as low strain rate, high flow stress, difficulty in controlling microstructure and properties, and severe oxidation. This places high demands on molds and forming equipment, and results in long production cycles and high costs, which greatly limits the industrial application of titanium alloys.

[0003] Hydrogen, as a strong β-phase stabilizing element in titanium alloys, has a significant impact on the phase composition transformation and microstructure of titanium alloys, thereby improving the performance of titanium alloy parts. The effects of hydrogen on titanium alloys are as follows: (1) Hydrogen increases the stability of the β phase in titanium alloys and lowers the α→β phase transformation temperature; (2) Hydrogen improves the diffusion ability of alloying elements in titanium alloys; (3) Hydrogen promotes the proliferation of dislocations in titanium alloys; (4) The addition of hydrogen weakens the bonding between metal atoms in titanium alloys. Hydrogen has high and reversible solubility in titanium alloys. Titanium alloys have the characteristics of absorbing and releasing hydrogen, which makes hydrogen a temporary alloying element in titanium alloys. This is the physical basis of thermo-hydrogen processing (THP) technology for titanium alloys. THP changes the phase composition and microstructure of titanium alloys, reduces the phase transformation temperature, flow stress and deformation temperature, and improves its deformation performance. Then, vacuum annealing is used to reduce the hydrogen content in titanium alloys to meet the standard value, so that titanium alloy parts will not experience hydrogen embrittlement during use, thereby improving the performance of titanium alloy parts. Currently, the HTP process is applied to titanium alloy grades such as TA15, TC4, TC21, Ti3Al, TiZrAlV, and Ti-55. The HTP process can improve the forging and superplastic deformation properties of titanium alloys and has become a new plastic deformation process for difficult-to-deform titanium alloys.

[0004] The hot hydrogen treatment technology for titanium alloys typically includes three processes: hydrogen placement, hot hydrogen processing, and vacuum dehydrogenation. This patent focuses on the hydrogen placement process. CP-Ti (pure titanium) basically does not absorb hydrogen below 298℃; however, as the temperature increases, it reacts violently with hydrogen. CN105177481A uses hydrogen filling in a vacuum for hydrogen placement, while CN113278901A adjusts the hydrogen absorption content of titanium alloy plates by regulating the hydrogen partial pressure inside the furnace. Many reports indicate the use of hydrogen as the hydrogen source for titanium alloy hydrogen placement. However, hydrogen is a flammable gas, and the transportation, storage, and use of hydrogen cylinders are subject to strict requirements. Summary of the Invention

[0005] To address the aforementioned technical issues, a hydrogen treatment process for titanium alloys is provided.

[0006] The technical means employed in this invention are as follows:

[0007] A hydrogen treatment process for titanium alloys, comprising:

[0008] (1) After shot peening and pickling, the titanium alloy is placed in a vacuum furnace.

[0009] The pickling process is as follows:

[0010] Pickling solution: (1%-3%) HF + (25%-30%) HNO3 + (67%-84%) H2O;

[0011] Pickling temperature: room temperature;

[0012] Pickling time: 15-30 minutes.

[0013] (2) Calculate the mass m of TiH2 powder, and weigh TiH2 powder with a mass greater than m using an electronic balance and place it into the vacuum furnace;

[0014]

[0015] The molar mass of M:TiH2 is 49.88 g / mol;

[0016] V: Molar volume of H2 22.4 L / mol;

[0017] μ: the ratio of the volume of hydrogen gas replaced per unit volume to the volume of the titanium alloy; generally, 0 < μ ≤ 0.03;

[0018] V1: The volume of the titanium alloy;

[0019] V2: The volume of the vacuum furnace cavity.

[0020] (3) Heat to the hydrogen temperature, then keep warm and pressurized, and finally cool to room temperature.

[0021] The hydrogen placement process involves maintaining a pressure below 0.08 MPa inside the vacuum furnace.

[0022] Heat to a hydrogen placement temperature of 600℃-800℃ at a heating rate of 5-20℃ / min, and hold at temperature and pressure for 30-60 minutes.

[0023] Studies have shown that the DSC / TG curves of TiH2 raw material powder heated in argon atmosphere (Cao Jieyi, Xiao Pingan, Dai Kunliang, et al. Dehydrogenation law and kinetic calculation of TiH2 [J]. Chinese Journal of Nonferrous Metals, 2014, 24(3): 733-738.) indicate that there are two separate endothermic peaks during the heating process. The temperature range of the first endothermic peak is 436℃~526℃, and the temperature range of the second endothermic peak is 526℃~666℃. The decomposition of TiH2 powder in argon atmosphere is basically completed in three steps: TiH2→TiH 1.5 →Ti (solution) →Ti. Therefore, the protective gas in the vacuum furnace described in this invention is argon.

[0024] Compared with the prior art, the present invention has the following advantages:

[0025] This invention utilizes the high-temperature reaction of TiH2 powder to release hydrogen gas as the hydrogen source for hydrogen deposition in titanium alloys. TiH2 is a titanium hydride with a density of 3.91 g / cm³. 3 With a melting point of 450℃, TiH2 is chemically stable at room temperature but decomposes upon heating, releasing hydrogen gas and becoming pure titanium. TiH2 powder is widely used as an ideal foaming agent in the fields of aluminum foam and titanium powder metallurgy. Compared to H2, TiH2 powder has stable properties at room temperature, making it easier to store and transport. The pure titanium produced in the reaction can be recycled by adding hydrogen gas at high temperatures to produce TiH2 powder, allowing for its recyclability.

[0026] Based on the above reasons, this invention can be widely applied in fields such as hydrogen storage in titanium alloys. Detailed Implementation

[0027] It should be noted that, unless otherwise specified, the embodiments and features described in this invention can be combined with each other. The described embodiments are merely some, not all, of the embodiments of this invention. The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the invention or its application or use. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without inventive effort are within the scope of protection of this invention.

[0028] Example 1

[0029] A hydrogen treatment process for titanium alloys utilizes a horizontal tube furnace with a diameter of 40 mm and a length of 680 mm. The protective gas inside is argon (99.9%). The implementation method is as follows:

[0030] (1) Titanium alloy pretreatment: TC4 titanium alloy plates with dimensions of 20mm×20mm×20mm were sandblasted to remove oxide scale, then immersed in pickling solution for a period of time. The samples were then removed, rinsed with anhydrous ethanol, and quickly dried before being placed in a quartz boat for later use. Pickling process: The pickling solution was (1%-3%)HF + (25%-30%)HNO3 + (67%-84%)H2O, at room temperature, for 15-30 minutes.

[0031] (2) Prepare the powder: Based on m = 2.22 × 10 -3 The mass of TiH2 powder was calculated to be 57.4g using the formula: μ × (V1 + V2), where μ is the ratio of the volume of hydrogen gas replaced per unit volume to the volume of the titanium alloy; V1 is the volume of the TC4 titanium alloy plate; and V2 is the volume of the vacuum furnace cavity. 58g of TiH2 powder was weighed using an electronic balance and placed in a quartz boat. A larger quartz boat was then placed on top to prevent powder from splashing during ventilation.

[0032] (3) Furnace loading preparation: Place the quartz boat containing titanium alloy into the vacuum furnace chamber, aligning the quartz boat with the temperature probe. Then place the quartz boat containing TiH2 powder, plug both sides with furnace plugs, align the furnace plugs with the furnace chamber rim, and seal the furnace tube.

[0033] (4) Hydrogenation process:

[0034] a. Follow the equipment operation procedure to ensure a stable flow of argon gas into the furnace chamber. Pay close attention to the gas pressure gauge of the tubular furnace and confirm that the gas pressure is below 0.08MPa (if the gas pressure is higher than 0.08MPa, open the gas outlet valve of the tubular furnace to release the gas).

[0035] b. Turn on the main power of the tube furnace, set the heating process for hydrogen placement, with a heating rate of 5-20℃ / min, a hydrogen placement temperature of 600℃-800℃, and a holding time of 30-60min. Allow the sample to air cool to room temperature, then remove the sample to complete the hydrogen placement process for the titanium alloy.

[0036] Example 2

[0037] A hydrogen treatment process for titanium alloys utilizes a horizontal tube furnace with a diameter of 40 mm and a length of 680 mm. The protective gas inside is argon (99.9%). The implementation method is as follows:

[0038] (1) Pretreatment of titanium alloy: The TB2 titanium alloy plate with a sample size of 20mm×20mm×20mm was sandblasted to remove the oxide scale, then immersed in the pickling solution for a period of time. After that, the sample was taken out, rinsed with anhydrous ethanol, and then quickly dried and placed in a quartz boat for later use. Pickling process: The pickling solution was (1%-3%)HF + (25%-30%)HNO3 + (67%-84%)H2O, at room temperature, and the pickling time was 15min-30min.

[0039] (2) Prepare the powder: Based on m = 2.22 × 10 -3 The mass of TiH2 powder was calculated to be 57.4g using the formula: μ × (V1 + V2), where μ is the ratio of the volume of hydrogen gas replaced per unit volume to the volume of the titanium alloy; V1 is the volume of the TB2 titanium alloy plate; and V2 is the volume of the vacuum furnace cavity. 58g of TiH2 powder was weighed using an electronic balance and placed in a quartz boat. A larger quartz boat was then placed on top to prevent powder from splashing during ventilation.

[0040] (3) Furnace preparation: Place the quartz boat containing titanium alloy into the furnace chamber of the vacuum furnace, aligning the quartz boat with the temperature probe. Then place the quartz boat containing TiH2 powder, plug both sides with furnace plugs, align the furnace plugs with the furnace chamber rim, and seal the furnace tube.

[0041] (4) Hydrogenation process:

[0042] a. Follow the equipment operation procedure to ensure a stable flow of argon gas into the furnace chamber. Pay close attention to the gas pressure gauge of the tubular furnace and confirm that the gas pressure is below 0.08MPa (if the gas pressure is higher than 0.08MPa, open the gas outlet valve of the tubular furnace to release the gas).

[0043] b. Turn on the main power of the tube furnace, set the heating process for hydrogen placement, with a heating rate of 5-20℃ / min, a hydrogen placement temperature of 600℃-800℃, and a holding time of 30-60min. Allow the sample to air cool to room temperature, then remove the sample to complete the hydrogen placement process for the titanium alloy.

[0044] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A hydrogen treatment process for titanium alloys, characterized in that, include: (1) After shot peening and pickling, the titanium alloy is placed in a vacuum furnace; (2) Calculate the mass m of TiH2 powder, and weigh a mass greater than m of TiH2 powder using an electronic balance and place it into the vacuum furnace; where m = 2.22 × 10 -3 ×μ×(V1+V2), where μ is the ratio of the volume of hydrogen gas replaced per unit volume to the volume of the titanium alloy; V1 is the volume of the titanium alloy; V2 is the volume of the vacuum furnace cavity; the titanium alloy and TiH2 powder are respectively loaded into different quartz boats; (3) Heat to the hydrogen temperature, then keep warm and pressurized, and finally cool to room temperature.

2. The hydrogen treatment process for titanium alloys according to claim 1, characterized in that, The pickling process is as follows: Pickling solution: (1%-3%) HF + (25%-30%) HNO3 + (67%-84%) H2O; Pickling temperature: room temperature; Pickling time: 15min-30min.

3. The hydrogen treatment process for titanium alloys according to claim 1, characterized in that, The hydrogen placement process involves maintaining a pressure below 0.08 MPa inside the vacuum furnace. Heat to a hydrogen placement temperature of 600℃-800℃ at a heating rate of 5~20℃ / min, and hold at temperature and pressure for 30min-60min.

4. The hydrogen treatment process for titanium alloys according to claim 1, characterized in that: 0 < μ ≤ 0.

03.

5. The hydrogen treatment process for titanium alloys according to claim 1, characterized in that, The protective gas inside the vacuum furnace is argon.

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