Hydrogen embrittlement resistant beta-type titanium alloy and application thereof

Abstract

The invention belongs to the field of titanium alloy materials, particularly relates to a hydrogen embrittlement-resistant beta-type titanium alloy and application thereof, and is expected to be applied to the fields of deep sea engineering, hydrogen energy and the like which bear extreme hydrogen environments. The hydrogen embrittlement-resistant beta-type titanium alloy comprises the following elements in percentage by mass: 8-28% of one or a mixture of Mo and V, 0-5% of one or a mixture of more than two of Al, Cr, Fe, Sn and Zr, and the balance of titanium, wherein the total mass fraction of the Mo and the V is 8-28%, and the total mass fraction of the Al, the Cr, the Fe, the Sn and the Zr is 0-5%. The alloy is metastable beta titanium alloy or beta single-phase titanium alloy, has high hydrogen solid solubility and inhibits brittle hydride transformation, main alloying elements are Mo and V elements, high corrosion resistance and hydrogen permeation resistance of the material are guaranteed, and other alloy elements are combined to optimize the comprehensive mechanical property of the alloy. The hydrogen embrittlement resistant beta-type titanium alloy material is reasonable in design, the preparation method is simple and controllable, and large-scale industrial application is facilitated.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of titanium alloy materials, and specifically relates to a hydrogen embrittlement resistant beta titanium alloy and application thereof, which is expected to be applied in the field of deep sea engineering and hydrogen energy and other fields bearing extreme hydrogen environment. BACKGROUND

[0002] Titanium alloy has excellent characteristics such as light weight, high strength, corrosion resistance and high temperature resistance, and has a wide application prospect in the fields of water electrolysis hydrogen production, hydrogen fuel cell, hydrogen transport and deep sea exploration. The service conditions of the above-mentioned fields are harsh hydrogen environment, and hydrogen embrittlement failure is easy to occur, and the hydrogen resistance directly affects the structural stability, durability and efficiency of the components. The hydrogen-induced brittleness of metal materials usually includes the following three mechanisms: a) hydrogen-induced local plasticity, hydrogen diffusion causes lattice distortion of metal materials in local area to induce plastic deformation, and highly localized plastic deformation induces micro crack nucleation; b) hydrogen-induced cleavage fracture, hydrogen reduces the atomic binding force, and the elastic stress of the crack tip induces hydrogen enrichment, which accelerates crack propagation; c) hydride-induced brittleness, titanium hydride is a brittle phase, which can induce crack initiation and propagation.

[0003] The solid solubility of hydrogen in alpha-Ti is low (about 7 at. % at room temperature), and brittle hydride precipitates are easy to produce, which aggravates the risk of hydrogen embrittlement. In the body-centered cubic beta-Ti, the room temperature solid solubility of hydrogen can reach 50 at. %, which is much higher than that of alpha-Ti, and its high hydrogen capacity can inhibit the formation of hydride and hydrogen embrittlement failure. Alloying elements can affect the dissociation, adsorption of hydrogen on the surface of titanium alloy and the diffusion of hydrogen in the matrix. Therefore, by doping alloying elements in beta-Ti, the permeation of hydrogen into the titanium matrix can be inhibited, and the hydrogen resistance of the material can be further improved.

[0004] A Chinese invention patent with the patent authorization publication number CN114369779B discloses a high-strength hydrogen embrittlement resistant pure titanium and a preparation method thereof. The method obtains pure titanium with high strength and excellent hydrogen embrittlement resistance by simple single deformation and single annealing treatment of industrial pure titanium. However, the hydrogen embrittlement resistance depends on the processing technology (such as deformation, annealing, etc.) rather than the composition design, the process stability is poor, and the strength of the pure titanium is low, which is difficult to meet the demand of high-strength structural parts for deep-sea engineering and hydrogen energy equipment. A Chinese invention patent with the patent application publication number CN118272699A discloses a hydrogen embrittlement resistant TC4 titanium alloy and a preparation method thereof. The alloy is based on TC4 titanium alloy (α+β type), and a net basket structure is obtained by TIG additive manufacturing. Since the alloy type is α+β dual phase and the β phase content is low, the hydrogen solubility is limited, and the hydrogen embrittlement resistance depends on the optimization of the microstructure (uniform dual phase). In a high hydrogen concentration environment, hydrogen is still prone to accumulate at the phase interface. A Chinese invention patent with the patent application publication number CN108950298A discloses a hydrogen embrittlement resistant titanium alloy for biomedical implant and a production method thereof. The alloy is mainly used in the field of biomedical implant, and the hydrogen embrittlement resistance depends on the Nd-rich second phase particles. The alloy type is α+β type, and full β phase structure cannot be formed. The hydrogen solubility at room temperature is much lower than that of β type titanium alloy, and brittle hydride is prone to precipitate.

[0005] Currently, there is no patent related to the hydrogen embrittlement resistance of β type titanium alloy to meet the increasing demand for engineering application of hydrogen embrittlement resistant titanium alloy. SUMMARY

[0006] The present application aims to provide a hydrogen embrittlement resistant β type titanium alloy and its application. By improving the corrosion resistance and inhibiting the penetration of hydrogen, the hydrogen corrosion resistance of the material is improved, solving the problems of low hydrogen capacity, easy precipitation of brittle hydride, and inability to resist electrochemical corrosion in extreme corrosion and hydrogen environment in the prior art.

[0007] To achieve the above-mentioned purpose, the technical scheme adopted by the present application is as follows:

[0008] A hydrogen embrittlement resistant β type titanium alloy, which comprises the following elements in mass percentage: one or a mixture of both of Mo and V in a total mass fraction of 8% to 28%, one or a mixture of two or more of Al, Cr, Fe, Sn and Zr in a total mass fraction of 0% to 5%, and the balance being titanium.

[0009] The hydrogen embrittlement resistant β type titanium alloy, when Mo and V are mixed, the mass fraction of Mo is 5% to 20%, and the mass fraction of V is 3% to 8%.

[0010] The anti-hydrogen embrittlement beta titanium alloy is a metastable beta titanium alloy or a beta single-phase titanium alloy, has a high hydrogen solid solution degree, inhibits brittle hydride transformation, and mainly comprises Mo and V elements; the Mo element is used for improving the corrosion resistance and hydrogen permeation resistance of the alloy; and the V element is used for maintaining the beta phase stability and hydrogen permeation resistance, thereby ensuring the high corrosion resistance and hydrogen permeation resistance of the material.

[0011] The anti-hydrogen embrittlement beta titanium alloy is heat treated at 30 DEG C to 70 DEG C above the beta phase transition point, the heating rate is not greater than 10 DEG C / s, the holding time is 1 to 1.5 h, and the cooling rate mode is water cooling.

[0012] The anti-hydrogen embrittlement beta titanium alloy is heat treated at 30 DEG C to 70 DEG C above the beta phase transition point, the heating rate is not greater than 10 DEG C / s, the holding time is 1 to 1.5 h, and the cooling rate mode is water cooling.

[0013] The anti-hydrogen embrittlement beta titanium alloy has a hydrogen room-temperature solid solution degree of greater than or equal to 40 at.%, a corrosion current density in a pure phosphoric acid solution of less than or equal to 1.52*10 -6 A·cm -2 , and a corrosion potential in the pure phosphoric acid solution of greater than or equal to -0.35 V vs Ag / AgCl.

[0014] The anti-hydrogen embrittlement beta titanium alloy is used in an extreme hydrogen environment in a deep-sea engineering or a hydrogen energy field.

[0015] The anti-hydrogen embrittlement beta titanium alloy is used in an extreme hydrogen environment in a deep-sea engineering or a hydrogen energy field.

[0016] The design idea of the present application is:

[0017] The application is doped by Mo and V elements, by controlling the total mass fraction of Mo and V to be 8% to 28%, to ensure that the alloy forms a beta single phase or a metastable beta phase structure, to obtain a beta titanium alloy to improve the hydrogen storage capacity of the material, the room temperature solid solubility of hydrogen in beta-Ti can reach 50at.%, and the high hydrogen storage capacity inhibits the formation of hydride and hydrogen embrittlement failure, and the hydrogen room temperature solid solubility of beta-Ti is much higher than that of alpha-Ti, so that the nucleation and growth of brittle hydride are fundamentally inhibited. Mo element is used to improve the corrosion resistance of the alloy, and Mo element doping can increase the H reaction rate, accelerate the synthesis of hydrogen atoms into hydrogen molecules to separate from the sample surface, and also can hinder the diffusion of hydrogen in the sample; V element is used to maintain the stability of beta phase and the hydrogen diffusion resistance, to avoid the transition of beta phase to alpha phase due to temperature or stress fluctuation, and to assist in inhibiting hydrogen diffusion and forming a synergistic hydrogen resistance effect with Mo; other alloy elements control the comprehensive mechanical properties of the alloy, and the total mass fraction of auxiliary elements such as Al, Cr, Fe, Sn and Zr is controlled to be 0% to 5%, so that the beta phase stability is not affected, and the comprehensive mechanical properties (such as strength and toughness) of the alloy are controlled by solid solution strengthening or fine grain strengthening, and the requirements of hydrogen embrittlement resistance and structure bearing are considered.

[0018] The Ti-Mo-V titanium alloy designed in the application can not only ensure the corrosion resistance of the material in acid and alkali environments, but also hinder the diffusion of hydrogen, thereby improving the corrosion resistance and hydrogen embrittlement resistance of the material in a corrosive environment. The alloy is a metastable beta titanium alloy or a beta single-phase titanium alloy, has a high hydrogen solid solubility, inhibits the transition of brittle hydride, mainly contains Mo and V elements, ensures high corrosion resistance and hydrogen permeation resistance of the material, and optimizes the comprehensive mechanical properties of the alloy by combining other alloy elements.

[0019] Compared with the prior art, the application has the following advantages and beneficial effects:

[0020] 1. The content of Mo and / or V in the application is 8% to 28%, which can basically realize the preparation of a beta titanium alloy with controllable cost, so that the alloy has high hydrogen storage capacity, corrosion resistance and hydrogen diffusion resistance, and finally has excellent hydrogen embrittlement resistance. Through the synergistic effect of high hydrogen storage capacity of beta phase and Mo / V hydrogen permeation resistance, the hydrogen content of the alloy after hydrogen charging is very low, and there is no hydrogen-induced crack or corrosion.

[0021] 2. When the total amount of (Al, Cr, Fe, Sn, Zr) elements is 0% to 5%, the comprehensive mechanical properties of the material can be further controlled.

[0022] 3. The beta titanium alloy of the application maintains the beta phase structure at high temperature, so that the material has better processing performance and formability, and is more conducive to the preparation of complex hydrogen-resistant structural parts.

[0023] 4. The anti-hydrogen embrittlement β-type titanium alloy material has reasonable design, simple and controllable preparation method, and is convenient for large-scale industrial application. BRIEF DESCRIPTION OF DRAWINGS

[0024] Figure 1 are potentiodynamic polarization curves of different alloys. In the figure, the horizontal coordinate Log|Current density| is the logarithmic value of the absolute value of the current density (mA / cm 2 ), and the vertical coordinate Potential is the electrode potential (V vs Ag / AgCl).

[0025] Figure 2 are linear sweep voltammetry curves of different alloys. In the figure, the horizontal coordinate Potential is the electrode potential (V vs Ag / AgCl), and the vertical coordinate Current density is the current density (mA / cm 2 ).

[0026] Figure 3 is the hydrogen distribution in the sample after electrochemical hydrogen charging obtained by using neutron imaging technology. Wherein, a is Ti-6Al-4V alloy (comparative example 1), b is Ti-Fe alloy (comparative example 2), c is Ti-Cr alloy (comparative example 3), d is Ti-V alloy (example 4), e is Ti-Mo alloy (example 5), and f is Ti-6Mo-3V alloy (example 6).

[0027] Figure 4 is the hydrogen content of different alloys after electrochemical hydrogen charging obtained by using a chemical analysis method. In the figure, the horizontal coordinate is different alloys, and the vertical coordinate H is the hydrogen content (wt%). DETAILED DESCRIPTION

[0028] In the specific implementation process, the application proposes a preparation method of an anti-hydrogen embrittlement β-type titanium alloy, comprising the following steps:

[0029] (1) Preparation of the alloy: five kinds of β-type titanium alloys (the atomic percentage of alloy elements is all 15%) are designed, and the mass percentages are Ti-Fe alloy (Fe 17.1%, comparative example 1), Ti-Cr alloy (Cr 16.1%, comparative example 2), Ti-V alloy (V 15.8%, comparative example 3), Ti-Mo alloy (Mo 26.1%, example 1), and Ti-Mo-V alloy (Mo: 11.3%, V: 3.0%, example 2). The raw materials after proportioning are melted by using a vacuum consumable electrode melting furnace, oxidation or impurity introduction caused by contact between the raw materials and air in the melting process is avoided through a vacuum environment, and the uniformity of the alloy composition is ensured.

[0030] (2) Heat treatment: five alloy ingots were put into a resistance heating furnace after being sealed in a vacuum quartz tube, and the heat treatment temperature was 1000°C (β single phase region). After holding for 1 h, water cooling was performed to obtain a β single phase structure.

[0031] (3) Corrosion performance detection: 10x10x2mm samples were cut from six alloy ingots for surface corrosion performance detection. The solution was pure phosphoric acid, which provided a relatively extreme corrosion environment. The potentiodynamic polarization curve obtained is shown in Figure 1 , and the corrosion current density (I corr ) and corrosion potential (E corr ) obtained after fitting are shown in Table 1. The surface oxide film of the titanium alloy can effectively isolate the titanium alloy from direct contact with the external corrosion medium. The smaller the corrosion current of the alloy, the more positive the corrosion potential, the more stable the surface passivation film of the alloy, and the better the corrosion resistance of the alloy. The corrosion current of Ti-Mo and Ti-Mo-V alloys is significantly smaller than that of other alloys, and the corrosion potential is more positive, indicating that these two alloys have higher corrosion resistance.

[0032] Table 1 Corrosion current density and corrosion potential of different alloys

[0033]

[0034] As shown in Table 1, the corrosion current density of the hydrogen embrittlement resistant β-type titanium alloy is at a very low level (such as Ti-Mo alloy as low as 3.68x10 -7 A·cm -2 , and Ti-Mo-V alloy as 1.52x10 -6 A·cm -2 ), which is much better than the same index of the prior art; in addition, the corrosion potential of the hydrogen embrittlement resistant β-type titanium alloy is significantly higher (such as Ti-Mo alloy as -0.11V vs Ag / AgCl, and Ti-Mo-V alloy as -0.35V vs Ag / AgCl), which reflects stronger passivation film stability.

[0035] (4) Hydrogen evolution reaction rate detection: 10x10x2mm samples were cut from six alloy ingots for hydrogen evolution reaction rate detection. The solution was pure phosphoric acid, which provided a relatively extreme corrosion environment. The linear voltammetry curve obtained is shown in Figure 2 . At the same current density, the closer the potential to 0V, the faster the hydrogen evolution reaction. Compared with other alloys, the hydrogen evolution reaction rate of Ti-Mo, Ti-Mo-V and Ti-Fe alloys is significantly greater than that of the other three alloys, and hydrogen atoms can form hydrogen molecules to escape from the sample surface more quickly, and it is difficult to enrich on the sample surface.

[0036] (4) Electrochemical hydrogen charging: 8x8x6mm samples were cut from six alloy ingots for surface electrochemical hydrogen charging treatment. The hydrogen charging solution is 1 / 3 mass of phosphoric acid + 2 / 3 mass of glycerol, which provides a more extreme hydrogen environment, and hydrogen is more easily enriched on the sample surface, accelerating hydrogen diffusion. After hydrogen charging, the Ti-6Al-4V alloy surface appears obvious corrosion, the Ti-Fe alloy is obviously cracked and broken, the Ti-Cr alloy surface appears hydrogen-induced cracks, and the Ti-V surface also appears slight cracks, and the Ti-Mo, Ti-Mo-V alloy surface does not appear corrosion and cracks, which is consistent with the above-mentioned Ti-Mo, Ti-Mo-V having higher corrosion resistance.

[0037] (5) Neutron imaging characterization: The hydrogen distribution of the five alloy samples after hydrogen charging is characterized by neutron imaging technology, as shown in Figure 3 Ti-6Al-4V hydrogen is enriched on the sample surface, Ti-Fe and Ti-Cr alloys have more uniform diffusion and significantly higher concentration, while Ti-V, Ti-Mo and Ti-Mo-V alloys have significantly reduced hydrogen content, indicating that Fe and Cr elements accelerate hydrogen diffusion in the sample, and V and Mo elements can significantly inhibit hydrogen permeation and diffusion.

[0038] (6) Chemical analysis: The hydrogen content of the hydrogen-charged sample was detected by chemical analysis, and the results were consistent with the neutron imaging rules, as shown in Figure 4 The hydrogen content in Ti-V, Ti-Mo and Ti-Mo-V alloys is significantly lower than that in Ti-6Al-4V, Ti-Fe and Ti-Cr alloys.

[0039] The implementation results show that the alloy mainly containing Fe and Cr elements has lower corrosion resistance and hydrogen diffusion resistance, and the alloy mainly containing V element can inhibit hydrogen diffusion, but has lower corrosion resistance. The Ti-Mo and Ti-Mo-V β-type titanium alloys mainly containing Mo element proposed in the present application can not only achieve higher corrosion resistance, but also can significantly inhibit hydrogen permeation and diffusion, improve the hydrogen resistance of the material, and have good economic benefit and popularization value.

Claims

1. A β-type titanium alloy resistant to hydrogen embrittlement, characterized in that, By mass percentage, the hydrogen embrittlement resistant β-type titanium alloy comprises the following elements: 8% to 28% of the total mass fraction of one or a mixture of two of Mo and V, 0% to 5% of the total mass fraction of one or a mixture of two or more of Al, Cr, Fe, Sn, and Zr, with the balance being titanium.

2. The hydrogen-embrittlement-resistant β-type titanium alloy according to claim 1, characterized in that, When Mo and V are mixed, the mass fraction of Mo is 5%–20% and the mass fraction of V is 3%–8%.

3. The hydrogen-embrittlement-resistant β-type titanium alloy according to claim 1, characterized in that, Hydrogen embrittlement resistant β-type titanium alloys are metastable β-titanium alloys or β single-phase titanium alloys with high hydrogen solid solubility, which inhibits the transformation of brittle hydrides. The main alloying elements are Mo and V. Mo is used to improve the alloy's corrosion resistance and hydrogen permeation resistance, while V maintains the stability of the β phase and hydrogen permeation resistance, thus ensuring the material's high corrosion resistance and hydrogen permeation resistance.

4. The hydrogen-embrittlement-resistant β-type titanium alloy according to claim 1, characterized in that, Hydrogen-embrittlement resistant β-type titanium alloys are heat-treated at 30℃~70℃ above the β phase transformation point, with a heating rate not exceeding 10℃ / s, a holding time of 1~1.5h, and water cooling.

5. The hydrogen-embrittlement-resistant β-type titanium alloy according to claim 4, characterized in that, The heating equipment for heat treatment is a resistance furnace with a temperature control accuracy of ±10℃.

6. The hydrogen-embrittlement-resistant β-type titanium alloy according to claim 1, characterized in that, Hydrogen-resistant β-type titanium alloys have a room temperature hydrogen solubility ≥40 at.%, and a corrosion current density ≤1.52×10⁻⁶ in pure phosphoric acid solution. -6 A·cm -2 The corrosion potential in pure phosphoric acid solution is ≥-0.35V vs Ag / AgCl.

7. The application of the hydrogen-embrittlement-resistant β-type titanium alloy according to any one of claims 1 to 6, characterized in that, Hydrogen-embrittlement resistant beta-type titanium alloys are used in extreme hydrogen-contaminated environments, such as deep-sea engineering or hydrogen energy fields.

8. The application of the hydrogen-embrittlement-resistant β-type titanium alloy according to claim 7, characterized in that, Applications in deep-sea engineering include deep-sea pressure-resistant structural components or hydrogen-bearing components for underwater oil and gas extraction equipment. Applications in the hydrogen energy field include water electrolysis hydrogen production electrodes, hydrogen fuel cell bipolar plates, or high-pressure hydrogen transportation pipelines.

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