阅读说明：本技术 一种耐硝酸腐蚀的Ti35钛合金 (Nitric acid corrosion resistant Ti35 titanium alloy ) 是由 吴金平 赵恒章 赵彬 杨帆 张于胜 潘晓龙 田丰 于 2020-12-03 设计创作，主要内容包括：本发明公开了一种耐硝酸腐蚀的Ti35钛合金,其特征在于,由以下质量含量的成分组成：钽5.5％～6.5％,氧0.07％～0.15％,余量为钛及不可避免的杂质。本发明的Ti35钛合金通过控制钽的质量含量为5.5％～6.5％,在兼顾材料低成本的同时,保证了Ti35钛合金具有稳定可靠的低腐蚀速率；同时采用氧作为间隙原子添加到钛合金中并控制氧的质量含量为0.07％～0.15％,有效提高Ti35钛合金的抗拉强度至350MPa以上,且Ti35钛合金的延伸率保持在25％以上,从而有效调控了Ti35钛合金的强塑性,方法简单,便于工业化应用。(The invention discloses a nitric acid corrosion resistant Ti35 titanium alloy which is characterized by comprising the following components in percentage by mass: 5.5 to 6.5 percent of tantalum, 0.07 to 0.15 percent of oxygen, and the balance of titanium and inevitable impurities. The Ti35 titanium alloy of the invention ensures that the Ti35 titanium alloy has stable and reliable low corrosion rate by controlling the mass content of tantalum to be 5.5-6.5%, and simultaneously considering the low cost of the material; meanwhile, oxygen is used as interstitial atoms to be added into the titanium alloy, the mass content of the oxygen is controlled to be 0.07-0.15%, the tensile strength of the Ti35 titanium alloy is effectively improved to be more than 350MPa, and the elongation of the Ti35 titanium alloy is kept to be more than 25%, so that the strong plasticity of the Ti35 titanium alloy is effectively regulated, the method is simple, and the industrial application is facilitated.)

1. The nitric acid corrosion resistant Ti35 titanium alloy is characterized by comprising the following components in percentage by mass: 5.5 to 6.5 percent of tantalum, 0.07 to 0.15 percent of oxygen, and the balance of titanium and inevitable impurities.

2. The nitric acid corrosion resistant Ti35 titanium alloy according to claim 1, comprising the following components by mass: 5.5 to 6 percent of tantalum, 0.10 to 0.15 percent of oxygen, and the balance of titanium and inevitable impurities.

3. The nitric acid corrosion resistant Ti35 titanium alloy according to claim 1, comprising the following components by mass: 6 to 6.5 percent of tantalum, 0.07 to 0.10 percent of oxygen, and the balance of titanium and inevitable impurities.

4. The Ti35 titanium alloy with nitric acid corrosion resistance according to claim 1, wherein the inevitable impurities in the Ti35 titanium alloy include not more than 0.15% by mass of Fe, not more than 0.15% by mass of C, not more than 0.03% by mass of N, and not more than 0.01% by mass of H.

Technical Field

The invention belongs to the field of non-ferrous metal alloy materials, and particularly relates to a nitric acid corrosion resistant Ti35 titanium alloy.

Background

Spent fuel generated by a nuclear power plant is recycled by reprocessing the spent fuel through post-treatment, so that the emission and pollution of radioactive substances can be effectively reduced, and the utilization rate of uranium resources is improved. The international common Pricks post-treatment process is a chemical process of dissolving fuel pellets by using nitric acid, removing nuclear fission products and recovering nuclear fuel, key equipment such as a dissolver, an evaporator and the like in the process are used in radioactive ray high-temperature concentrated nitric acid containing various metal cations for a long time, the service environment is extremely severe, and extremely high requirements are provided for the mechanical property, the process property and the corrosion resistance of equipment materials.

Generally, stainless steel materials are corroded in boiling nitric acid solution due to intergranular chromium deficiency, and for ultralow-carbon stainless steel materials resistant to nitric acid corrosion, such as 000Cr25Ni20, the ultralow-carbon stainless steel is strongly corroded in boiling nitric acid solution containing metal cations due to high oxidizability of the metal cations. Titanium has good corrosion resistance in nitric acid, and the mechanism is that a protective oxide film is formed on the surface of the titanium to prevent the interaction of a corrosive liquid and a metal matrix, so that the corrosion rate of the metal matrix is reduced. However, in high-temperature concentrated nitric acid, the corrosion resistance of titanium is obviously reduced due to the low compactness and bonding strength of a pure titanium oxide film, and the annual average corrosion rate of industrial pure titanium in a boiling 65% nitric acid solution exceeds 1.0mm/a, so that the requirement of engineering design cannot be met. In application practice, the Ti-Ta binary alloy obtained by adding Ta element into Ti has good nitric acid corrosion resistance.

KS50Ta (Ti-5Ta) alloy developed by Japan Kobe steel enhances the corrosion resistance of industrial pure titanium by adding 4 to 6 weight percent of tantalum element into the pure titanium, the annual average corrosion rate of the alloy in boiling nitric acid solution is 0.1 to 0.2mm/a, the tensile strength is 330MPa, the elongation is 23 percent, and the alloy has the defects of low strength and plasticity and slightly poor corrosion resistance.

Japanese Kohyo Steel institute Sho 61-42473 discloses a Ti-Ta-Si alloy having excellent nitric acid corrosion resistance, which is a ternary corrosion-resistant titanium alloy formed by adding 1-6% by weight of tantalum and 0.01-0.5% by weight of silicon to titanium, wherein corrosion of the Ti-Ta alloy is inhibited by the addition of a small amount of silicon element, but the inhibition effect is limited, and the addition of silicon element adversely affects the plasticity and workability of the Ti-Ta-based material.

The invention patent with the patent number ZL95101399.8 discloses a 550 MPa-grade nitric acid corrosion resistant titanium alloy, which is formed by adding 3-7 wt% of tantalum, 0.1-0.7 wt% of aluminum and 0.2-0.6 wt% of molybdenum into titanium, the strength of the quaternary corrosion resistant titanium alloy is improved to 550MPa, the corrosion rate reaches 0.1mm/a, but the elongation is only 23%, and the plasticity of the material needs to be further improved.

The material for nuclear chemical equipment must have high plasticity so as to reduce the difficulty of equipment and material processing, and meanwhile, the corrosion resistance of the material needs to be improved in order to ensure high safety and stability of equipment use and prolong the service life of the equipment.

Disclosure of Invention

The invention aims to solve the technical problem of providing a nitric acid corrosion resistant Ti35 titanium alloy aiming at the defects of the prior art. The Ti35 titanium alloy ensures that the Ti35 titanium alloy has stable and reliable low corrosion rate while considering the low cost of the material by controlling the mass content of tantalum to be 5.5-6.5%; meanwhile, oxygen is used as interstitial atoms to be added into the titanium alloy, the mass content of the oxygen is controlled to be 0.07-0.15%, the tensile strength of the Ti35 titanium alloy is effectively improved to be more than 350MPa, and the elongation of the Ti35 titanium alloy is kept to be more than 25%, so that the strong plasticity of the Ti35 titanium alloy is effectively regulated and controlled.

In order to solve the technical problems, the invention adopts the technical scheme that: the nitric acid corrosion resistant Ti35 titanium alloy is characterized by comprising the following components in percentage by mass: 5.5 to 6.5 percent of tantalum, 0.07 to 0.15 percent of oxygen, and the balance of titanium and inevitable impurities.

The research of the invention finds that Ta is taken as an alloying element, and Ta is addedThe content of the Ta and the corrosion rate of the titanium alloy are shown in figure 1, the abscissa in the figure 1 represents the mass content wt% of the Ta, the ordinate represents the corrosion rate mm/a of the titanium alloy, and B.T 6M HNO₃Represents the HNO at boiling (B.T)6M tested in FIG. 1₃The method is carried out in the middle, but the addition amount of Ta and the nitric acid corrosion resistance of the titanium alloy do not have a simple linear proportional relationship, when the addition amount of Ta is more than 1%, Ti and Ta form a passivation film with oxygen, and the titanium oxide film on the surface of the titanium alloy is pinned by tantalum oxide to form a strengthening effect, so that the nitric acid corrosion resistance of the titanium alloy is improved, the corrosion rate of the titanium alloy is reduced, when the addition amount of Ta is 5.5-6.5%, the change curve of the Ta content and the corrosion rate of the titanium alloy enters a low-corrosion platform region, the strengthening effect of the titanium oxide film on the surface of the titanium alloy pinned by tantalum oxide is saturated, the compactness and the dissolution resistance of the passivation film formed by Ti, Ta and oxygen both obtain peak values, the corrosion rate of the titanium alloy is reduced and slowed, the nitric acid corrosion resistance of the titanium alloy is improved slightly, and the increase of the Ta content does not obviously improve the nitric acid corrosion resistance of the, and too high Ta increases the cost of the material. Therefore, the mass content of tantalum in the Ti35 titanium alloy is controlled to be 5.5% -6.5%, the Ti35 titanium alloy is ensured to have stable and reliable low corrosion rate while the material cost is low, and the annual average corrosion can reach below 0.05 mm/a. Meanwhile, the Ti35 titanium alloy utilizes the solid solution strengthening principle, oxygen is used as interstitial atoms to be added into the titanium alloy, the mass content of the oxygen is controlled to be 0.07-0.15%, the interstitial atoms greatly improve the strength of the titanium alloy, the influence on the plasticity and corrosion resistance of the titanium alloy is small, the tensile strength of the Ti35 titanium alloy is effectively improved to be more than 350MPa, and the elongation of the Ti35 titanium alloy is kept to be more than 25%, so that the strong plasticity of the Ti35 titanium alloy is effectively regulated and controlled.

The nitric acid corrosion resistant Ti35 titanium alloy is characterized by comprising the following components in percentage by mass: 5.5 to 6 percent of tantalum, 0.10 to 0.15 percent of oxygen, and the balance of titanium and inevitable impurities.

The nitric acid corrosion resistant Ti35 titanium alloy is characterized by comprising the following components in percentage by mass: 6 to 6.5 percent of tantalum, 0.07 to 0.10 percent of oxygen, and the balance of titanium and inevitable impurities.

The above-mentioned nitric acid corrosion resistant Ti35 titanium alloy is characterized in that the mass content of iron in the inevitable impurities of the Ti35 titanium alloy is not more than 0.15%, the mass content of carbon is not more than 0.15%, the mass content of nitrogen is not more than 0.03%, and the mass content of hydrogen is not more than 0.01%. The mass content of iron in the inevitable impurities of the Ti35 titanium alloy is controlled to be not more than 0.15%, the reduction effect on the corrosion resistance of the Ti35 titanium alloy is avoided, the mass content of carbon is controlled to be not more than 0.15%, the mass content of nitrogen is controlled to be not more than 0.03%, the reduction effect of carbon and nitrogen with excessively high content on the plasticity of the Ti35 titanium alloy is avoided, the mass content of hydrogen is controlled to be not more than 0.01%, the hydrogen embrittlement of the Ti35 titanium alloy is avoided, and the low corrosion rate and the strong plasticity of the Ti35 titanium alloy are further ensured.

The preparation process of the nitric acid corrosion resistant Ti35 titanium alloy comprises the following steps: preparing raw materials according to the design components and content of a target product, uniformly mixing the raw materials, pressing the raw materials into an electrode block, welding the electrode block into a consumable electrode, carrying out vacuum consumable arc melting to obtain a Ti35 titanium alloy cast ingot, peeling the Ti35 titanium alloy cast ingot, cutting off a dead head, cogging and forging, carrying out intermediate forging, extrusion, rolling and other processes, processing into a forging piece, a plate, a bar or a pipe, and carrying out annealing treatment to obtain a finished product.

Compared with the prior art, the invention has the following advantages:

1. according to the invention, by controlling the addition of 5.5-6.5% of Ta and the mass content of oxygen to be 0.07-0.15%, the nitric acid corrosion resistance of Ti35 titanium alloy is effectively improved, the strength of Ti35 titanium alloy is greatly improved, the plasticity and nitric acid corrosion resistance of Ti35 titanium alloy are reduced, the strong plasticity of Ti35 titanium alloy is effectively regulated, and the material cost of Ti35 titanium alloy is reduced.

2. The Ti35 titanium alloy has the tensile strength of more than 350MPa, the elongation of more than 25 percent, good comprehensive performance matching of strength and plasticity, excellent nitric acid corrosion resistance and suitability for materials for nuclear chemical equipment.

3. The Ti35 titanium alloy of the invention obviously improves the performance of Ti35 titanium alloy by controlling the addition of oxygen, overcomes the defects of low plasticity and corrosion resistance of the existing nitric acid corrosion resistant material, has simple method and is convenient for industrialized application.

The technical solution of the present invention is further described in detail by the accompanying drawings and examples.

Drawings

FIG. 1 is a graph showing the change in the Ta content by mass and the corrosion rate of a titanium alloy.

Detailed Description

Example 1

The nitric acid corrosion resistant Ti35 titanium alloy of the embodiment comprises the following components by mass: 5.5% of tantalum, 0.15% of oxygen and the balance of titanium and inevitable impurities; the Ti35 titanium alloy contains inevitable impurities including 0.11 wt% of iron, 0.008 wt% of carbon, 0.003 wt% of nitrogen and 0.0006 wt% of hydrogen.

The preparation process of the Ti35 titanium alloy resistant to nitric acid corrosion of the embodiment is as follows: preparing raw materials according to the design components and content of a target product, then placing titanium powder and tantalum powder in the raw materials in a mixer according to the mass ratio of 3:2 for mixing for 5 hours to obtain mixed powder with uniform components, and mixing the mixed powder with titanium sponge and TiO₂Pressing into an electrode block by using a press after burdening, drying for 4 hours in an oven at the temperature of 80 ℃, then placing the electrode block in a vacuum plasma welding box to be welded into a consumable electrode, placing the consumable electrode in a vacuum consumable arc furnace to carry out three times of smelting to obtain a Ti35 titanium alloy cast ingot, peeling and cutting off a riser on the Ti35 titanium alloy cast ingot, then carrying out cogging forging at 1050 ℃, then carrying out intermediate forging, extrusion, rolling and other processes to obtain a bar material, controlling the total deformation to be 80%, and then carrying out annealing treatment at the temperature of 650 ℃ to obtain the nitric acid corrosion resistant Ti35 titanium alloy bar.

Example 2

The nitric acid corrosion resistant Ti35 titanium alloy of the embodiment comprises the following components by mass: 5.7% of tantalum, 0.13% of oxygen and the balance of titanium and inevitable impurities; the Ti35 titanium alloy contains inevitable impurities including 0.09% by mass of iron, 0.004% by mass of carbon, 0.005% by mass of nitrogen and 0.001% by mass of hydrogen.

The preparation process of the Ti35 titanium alloy resistant to nitric acid corrosion of the embodiment is as follows: preparing raw materials according to the design components and content of target products, and then adding titanium sponge and TiO in the raw materials₂Mixing the powder and Ti-40% Ta intermediate alloy chips, pressing into an electrode block, drying in an oven at 80 ℃ for 4h, then placing in a vacuum plasma welding box to weld into a consumable electrode, placing the consumable electrode in a vacuum consumable arc furnace to carry out three times of smelting to obtain a Ti35 titanium alloy ingot, peeling and cutting off a riser of the Ti35 titanium alloy ingot, then carrying out cogging forging at 11000 ℃, then carrying out intermediate forging, extrusion, rolling and other processes to obtain a bar, controlling the total deformation amount to be 80%, and then carrying out annealing treatment at 650 ℃ to obtain the nitric acid corrosion resistant Ti35 titanium alloy bar.

Example 3

The nitric acid corrosion resistant Ti35 titanium alloy of the embodiment comprises the following components by mass: 6% of tantalum, 0.10% of oxygen and the balance of titanium and inevitable impurities; the Ti35 titanium alloy contains inevitable impurities including 0.010 wt% of iron, 0.005 wt% of carbon, 0.003 wt% of nitrogen and 0.0009 wt% of hydrogen.

The preparation process of the Ti35 titanium alloy resistant to nitric acid corrosion of the embodiment is as follows: preparing raw materials according to the design components and content of target products, and then adding titanium sponge and TiO in the raw materials₂Mixing the powder with Ti-40% Ta intermediate alloy chips, pressing into an electrode block, drying in an oven at 80 ℃ for 4h, welding in a vacuum plasma welding box to form a consumable electrode, placing the consumable electrode in a vacuum consumable arc furnace for three times to obtain a Ti35 titanium alloy ingot, peeling off the Ti35 titanium alloy ingot, cutting off a dead head, cogging and forging at 1100 ℃, then performing intermediate forging, extrusion, rolling and other processes to obtain a bar, and controlling the total deformation amount to be 70%And then annealing treatment is carried out at 650 ℃ to obtain the Ti35 titanium alloy rod resistant to nitric acid corrosion.

Example 4

The nitric acid corrosion resistant Ti35 titanium alloy of the embodiment comprises the following components by mass: 6.2% of tantalum, 0.09% of oxygen and the balance of titanium and inevitable impurities; the Ti35 titanium alloy contains inevitable impurities including 0.02 wt% of iron, 0.007 wt% of carbon, 0.008 wt% of nitrogen and 0.003 wt% of hydrogen.

The preparation process of the Ti35 titanium alloy resistant to nitric acid corrosion of the embodiment is as follows: preparing raw materials according to the design components and content of a target product, then placing titanium powder and tantalum powder in a mixer according to the mass ratio of 3:2 for mixing for 5 hours to obtain mixed powder with uniform components, placing the mixed powder in a sintering furnace after cold isostatic pressing, sintering for 24 hours at 1200 ℃ to obtain Ti-40% Ta intermediate alloy powder sintering strips, and mixing the Ti-40% Ta intermediate alloy powder sintering strips with titanium sponge and TiO₂The method comprises the steps of preparing powder, pressing into an electrode block by a press machine, drying in an oven at 80 ℃ for 4 hours, then placing in a vacuum plasma welding box to weld into a consumable electrode, placing the consumable electrode in a vacuum consumable arc furnace to carry out three times of smelting to obtain a Ti35 titanium alloy ingot, peeling and cutting off a riser of the Ti35 titanium alloy ingot, then carrying out cogging forging at 1100 ℃, then carrying out intermediate forging, extrusion, rolling and other processes to obtain a bar, controlling the total deformation to be 70%, and then carrying out annealing treatment at 680 ℃ to obtain the nitric acid corrosion resistant Ti35 titanium alloy bar.

Example 5

The nitric acid corrosion resistant Ti35 titanium alloy of the embodiment comprises the following components by mass: 6.5% of tantalum, 0.07% of oxygen and the balance of titanium and inevitable impurities; the Ti35 titanium alloy contains inevitable impurities including 0.002 wt% of iron, 0.005 wt% of carbon, 0.004 wt% of nitrogen and 0.001 wt% of hydrogen.

The preparation process of the Ti35 titanium alloy resistant to nitric acid corrosion of the embodiment is as follows: preparing raw materials according to the design components and content of a target product, and then mixing titanium powder and tantalum powder according to the mass ratio of 3:2Mixing for 5h in a mixer to obtain mixed powder with uniform components, cold isostatic pressing the mixed powder, sintering in a sintering furnace at 1200 ℃ for 24h to obtain Ti-40% Ta intermediate alloy powder sintering strips, and mixing the Ti-40% Ta intermediate alloy powder sintering strips with titanium sponge and TiO₂The method comprises the steps of preparing powder, pressing into an electrode block by a press machine, drying in an oven at 80 ℃ for 4 hours, then placing in a vacuum plasma welding box to weld into a consumable electrode, placing the consumable electrode in a vacuum consumable arc furnace to carry out three times of smelting to obtain a Ti35 titanium alloy ingot, peeling and cutting off a riser of the Ti35 titanium alloy ingot, then carrying out cogging forging at 1150 ℃, then carrying out intermediate forging, extrusion, rolling and other processes to obtain a bar, controlling the total deformation to be 60%, and then carrying out annealing treatment at 680 ℃ to obtain the nitric acid corrosion resistant Ti35 titanium alloy bar.

Through detection, the results of the mechanical properties of the nitric acid corrosion resistant Ti35 titanium alloy rods of the embodiments 1 to 5 are shown in the following table 1, the results of the nitric acid corrosion resistance are shown in the following table 2, and the results of the nitric acid corrosion resistant Ti35 titanium alloy and the similar titanium alloy are shown in the following table 3.

TABLE 1

As is apparent from Table 1, the nitric acid corrosion resistant Ti35 titanium alloy rods of examples 1 to 5 of the present invention had tensile strengths Rm of 370MPa or more, yield strengths Rp0.2 of 280MPa or more, elongations A after fracture of 28% or more, and impact toughness A_KUUp to 135J/cm²It is demonstrated that the nitric acid corrosion resistant Ti35 titanium alloy of the present invention has excellent strong plastic matching.

TABLE 2

As is clear from Table 2, the nitric acid corrosion resistant Ti35 titanium alloy rods of examples 1 to 5 of the present invention were boiled (B.T)8M HNO₃Under the experimental conditions of (a) and (b),the corrosion rate is not more than 0.05mm/a, which shows that the Ti35 titanium alloy has excellent nitric acid corrosion resistance.

TABLE 3

As can be seen from Table 3, the tensile strength Rm and the yield strength Rp0.2 of the Ti35 titanium alloy resistant to nitric acid corrosion are both between that of the Ti-55C titanium alloy and that of the KS50Ta titanium alloy, the elongation A after fracture is higher than that of the Ti-55C titanium alloy and that of the KS50Ta titanium alloy, and the impact toughness A of the Ti35 titanium alloy resistant to nitric acid corrosion is higher than that of the KS 50C titanium alloy_KUThe corrosion rate of the Ti-55C titanium alloy is higher than that of the Ti-55C titanium alloy and that of the KS50Ta titanium alloy, so that the nitric acid corrosion resistant Ti35 titanium alloy has excellent nitric acid corrosion resistance, better plasticity and excellent strong plasticity matching.

The above description is only for the preferred embodiment of the present invention, and is not intended to limit the present invention in any way. Any simple modification, change and equivalent changes of the above embodiments according to the technical essence of the invention are still within the protection scope of the technical solution of the invention.