CN108893654A - A kind of full α phase fine grain high-strength anticorrosion titanium alloy and preparation method thereof - Google Patents

Abstract

The invention provides an all-alpha-phase fine-grained high-strength, tough, and corrosion-resistant titanium alloy and a preparation method thereof. The all-alpha-phase, fine-grained, high-strength, and corrosion-resistant titanium alloy includes 1.8-2.5% of Al, 5-50% of Zr and the balance of Ti: the all-alpha-phase fine-grained high-strength and corrosion-resistant titanium alloy does not contain Pd. In the present invention, Zr and Ti are easy to form infinite solid solution, and zirconium element is easy to form zirconium oxide in corrosive medium, which can effectively improve the structural properties of the passivation film of titanium alloy, significantly improve the corrosion resistance of titanium alloy, and With the increase of zirconium content, the passivation current density of the alloy gradually decreases, and the alloy gradually changes from uniform corrosion to localized corrosion; at the same time, the addition of Zr element to titanium alloy can significantly improve the corrosion resistance of titanium alloy. The formed ZrO ₂ can improve the oxide protective film layer of the alloy, thereby improving the ability of the alloy to resist corrosion.

Description

A kind of all-alpha-phase fine-grain high-strength and toughness corrosion-resistant titanium alloy and its preparation method

technical field

The invention relates to the technical field of titanium alloys, in particular to an all-alpha phase fine-grained high-strength and toughness corrosion-resistant titanium alloy and a preparation method thereof.

Background technique

Titanium and titanium alloys are widely used in marine engineering, aerospace, biomedical engineering, metallurgy, chemical industry, light industry and many other fields. With the widespread application of titanium and titanium alloys, the development of industry and the service environment have put forward more stringent requirements on the performance of titanium alloys. It is difficult for traditional titanium alloys to meet the current engineering application standards in terms of strength and corrosion resistance. The high-strength titanium corrosion-resistant alloy is one of the key directions of research, development and application at present.

Titanium and titanium alloys are actively used in the field of aircraft due to their outstanding characteristics of light weight and high strength. In addition, they also have excellent corrosion resistance, so they are widely used as materials for chemical industry equipment, thermal power, nuclear power generation equipment materials, Further applications such as seawater desalination equipment materials.

However, although titanium and titanium alloys have excellent corrosion resistance, the environments that can exhibit high corrosion resistance are limited to oxidizing acid (nitric acid) environments, neutral chloride environments such as seawater, and crevice corrosion resistance in high-temperature chloride environments. 1. Corrosion resistance in non-oxidizing acid liquid (hereinafter collectively referred to as "corrosion resistance") is insufficient.

In order to improve the corrosion resistance of titanium alloys in different environments, Ti-0.15Pd alloy (ASTM Gr.7) was developed. Although the titanium alloy shows excellent corrosion resistance, the ASTM Gr.7 requires the addition of expensive Pd element, the preparation cost of the titanium alloy is high, and the mechanical properties are insufficient, which limits the scope of application.

Contents of the invention

In view of this, the object of the present invention is to provide an all-α-phase fine-grained high-strength and tough corrosion-resistant titanium alloy and a preparation method thereof. The titanium alloy provided by the invention has good corrosion resistance in the chloride environment, and has low preparation cost.

The invention provides an all-alpha-phase fine-grained high-strength and tough corrosion-resistant titanium alloy, which comprises 1.8-2.5% of Al, 5-50% of Zr and the rest of Ti in terms of mass content; the all-alpha-phase fine-grained high-strength and tough Corrosion-resistant titanium alloys do not contain Pd.

Preferably, the all-α-phase fine-grained high-strength, tough and corrosion-resistant titanium alloy includes 0.10-0.12% of Ru, 5-30% of Zr and the rest of Ti.

Preferably, the all-α-phase fine-grained high-strength and tough corrosion-resistant titanium alloy is composed of basket-shaped α′ martensitic phase laths; the average width of the α’-phase laths in the structure of the high-strength and tough corrosion-resistant titanium alloy is 24.23- 79.41 μm.

The present invention also provides a method for preparing the all-α-phase fine-grained high-strength and corrosion-resistant titanium alloy described in the above technical solution, comprising the following steps:

(1) Obtain the as-cast alloy billet after melting the alloy raw material;

(2) deforming the as-cast alloy billet obtained in the step (1) after heat preservation treatment to obtain a densified alloy billet;

(3) Annealing the densified alloy billet obtained in the step (2) to obtain an all-alpha-phase fine-grained high-strength and tough corrosion-resistant titanium alloy.

Preferably, the smelting in the step (1) is vacuum arc smelting, and the temperature of the vacuum arc smelting is 2500-3000°C.

Preferably, the number of smelting in the step (1) is more than 5 times, and each smelting time is 3-5 minutes.

Preferably, the temperature of the heat preservation treatment in the step (2) is 850-950° C., and the time is 40-60 minutes.

Preferably, the deformation method in the step (2) is rolling deformation; the total deformation amount of the rolling deformation is 40-50%.

Preferably, the rolling deformation is multi-pass rolling, and the deformation amount of each pass is 15-20%;

When multi-pass rolling is adopted, after each pass of rolling, the rolled alloy billet is kept at the rolling deformation temperature for 5-10 minutes.

Preferably, the annealing treatment in the step (3) is as follows: heating the densified alloy billet to 750-830° C. in a furnace, keeping it warm for 30-60 minutes, and then cooling in a furnace.

The invention provides an all-alpha-phase fine-grained high-strength and tough corrosion-resistant titanium alloy, which comprises 1.8-2.5% of Al, 5-50% of Zr and the rest of Ti in terms of mass content; the all-alpha-phase fine-grained high-strength and tough Corrosion-resistant titanium alloys do not contain Pd.

The present invention strictly controls the content of each element, and improves the corrosion resistance and strength of titanium alloy through alloying; in the present invention, Zr and Ti are easy to form infinite solid solution, and zirconium element is easy to form zirconium oxide in corrosive medium, which can effectively improve The structural properties of the passivation film of titanium alloy can significantly improve the corrosion resistance of titanium alloy. With the increase of zirconium content in the alloy, the passivation current density of the alloy gradually decreases, and the alloy gradually changes from uniform corrosion to localized corrosion; at the same time, titanium The addition of Zr element in the alloy can significantly improve the corrosion resistance of the titanium alloy. After adding Zr to the titanium alloy, the ZrO2 formed _on the surface can improve the oxide protective film of the alloy, thereby improving the corrosion resistance of the alloy; Compared with Ti, the passivation potential of titanium oxide metal is more negative, and the passivation ability is stronger. Even in the environment of weak oxidation conditions, passivation can still occur, and it is easier to form a passivation film on the surface of the alloy. The corrosion resistance of the alloy in a variety of corrosive media Performance has been improved.

The experimental results show that the all-alpha-phase fine-grained high-strength and corrosion-resistant titanium alloy provided by the present invention has excellent corrosion resistance in a chloride environment (in non-oxidative acidity); compared with the contrast alloy obtained by the same treatment process, The anti-corrosion ability in sodium chloride solution has been improved by 59.85%, the yield strength has been increased by 104.8%, the tensile strength has been increased by 94.5%, and the strength has been greatly improved.

Description of drawings

Fig. 1 is the metallographic optical micrograph of the titanium alloy that embodiment 1 makes;

Fig. 2 is the metallographic optical micrograph of the titanium alloy that embodiment 2 makes;

Fig. 3 is the metallographic optical micrograph of the titanium alloy that embodiment 3 makes;

Fig. 4 is the metallographic optical micrograph of the titanium alloy that embodiment 4 makes;

Fig. 5 is the metallographic optical micrograph of the titanium alloy that embodiment 5 makes;

Fig. 6 is a dimension diagram of a tensile sample used in the tensile property test of the present invention.

Detailed ways

The present invention provides the present invention provides a full-alpha-phase fine-grained high-strength, high-strength, corrosion-resistant titanium alloy, which includes Al 1.8-2.5%, Zr 5-50% and the balance of Ti; the full-alpha-phase The fine-grained high-strength and corrosion-resistant titanium alloy does not contain Pd.

The all-alpha-phase fine-grained high-strength and tough corrosion-resistant titanium alloy provided by the present invention contains 1.8-2.5% of Al, preferably 2.2-2.5%, and more preferably 2.3-2.4% of Al by mass content. In the present invention, Al is an α-phase stable element, and the solid solution strengthening effect is obvious. A small amount of addition can greatly improve the strength of the titanium alloy, and the Al element is cheap, easy to smelt, light in texture, and can reduce the alloy density. And significantly increase the recrystallization temperature, thereby improving the thermal strength of the alloy.

The all-alpha-phase fine-grained high-strength and tough corrosion-resistant titanium alloy provided by the invention contains 5-50% of Zr, preferably 10-40%, and more preferably 12-28% of Zr in terms of mass content. In the present invention, since the addition of Zr elements will cause lattice distortion, these defects will lead to an increase in nucleation points and an increase in the density of nucleation during the nucleation process, which will play a role in grain refinement and achieve fine grain Strengthening: the element Zr is added to the matrix titanium, and the neutral element Zr that has little effect on the phase transition temperature forms an infinite solid solution with Ti, thereby achieving solid solution strengthening, and the passivation potential of Zr is more negative than that of Ti, even in weak oxidation Passivation can still occur in a conditional environment, which improves the ability to form a dense oxide film on the surface and improves its corrosion resistance.

The all-alpha-phase fine-grained high-strength and corrosion-resistant titanium alloy provided by the invention does not contain Pd and can achieve high corrosion resistance in different environments.

The all-alpha-phase fine-grained high-strength and toughness corrosion-resistant titanium alloy provided by the present invention, in addition to the above-mentioned elements, includes a balance of Ti in terms of mass content.

In the present invention, the full α-phase fine-grained high-strength and corrosion-resistant titanium alloy is preferably composed of typical basket-shaped α′ martensitic phase laths. In the present invention, the average width of the α' phase lath in the structure of the all-α-phase fine-grained high-strength and tough corrosion-resistant titanium alloy is preferably 24.23-79.41 μm, more preferably 35-40 μm.

The present invention also provides a method for preparing the all-α-phase fine-grained high-strength and corrosion-resistant titanium alloy described in the above technical solution, comprising the following steps:

(1) Obtain the as-cast alloy billet after melting the alloy raw material;

(2) deforming the as-cast alloy billet obtained in the step (1) after heat preservation treatment to obtain a densified alloy billet;

(3) Annealing the densified alloy billet obtained in the step (2) to obtain an all-alpha-phase fine-grained high-strength and tough corrosion-resistant titanium alloy.

In the invention, the alloy raw material is smelted to obtain the cast alloy billet. In the present invention, there is no special limitation on the type of the alloy raw material, and the alloy raw material well-known to those skilled in the art is used to obtain the titanium alloy with the target composition. In the present invention, the alloy raw materials preferably include sponge titanium, sponge zirconium and pure aluminum. In the present invention, there is no special limitation on the ratio of various alloy raw materials, as long as the final alloy composition can meet the requirements.

In the present invention, the smelting is preferably vacuum arc smelting, and the temperature of the vacuum arc smelting is preferably 2500-3000°C, more preferably 2750-2850°C. In the present invention, the vacuum degree of the vacuum arc melting is preferably 0.04-0.05 MPa, and it is carried out under the condition of argon. When vacuum arc melting is adopted, the present invention preferably first evacuates the vacuum degree in the furnace chamber to below 9×10 ^-3 Pa, and then introduces argon gas; The amount can be. In the present invention, the current of the vacuum arc melting is preferably 400-450A, more preferably 420-435A. The present invention has no special requirements on the specific implementation of the vacuum arc smelting, and those familiar to those skilled in the art can be used. In the present invention, the method of vacuuming first and then introducing argon gas can firstly prevent Ti and Zr from absorbing a large amount of hydrogen, oxygen and nitrogen at high temperature, resulting in oxidation, and can also provide ionized gas for arc smelting. In the present invention, the number of smelting is preferably more than 5 times, more preferably 6-10 times, and the as-cast alloy billet is obtained after smelting; the time of each smelting is preferably 3-5 minutes. In the present invention, when the smelting is repeated, the smelting is preferably carried out in a vacuum arc melting furnace; specifically: the metal raw material is smelted in an electric arc melting furnace to obtain a smelting liquid; then cooled to obtain a slab, and then turned over Smelting after casting the slab to obtain the smelting liquid again, cooling the smelting liquid again to obtain the slab, and repeating this for more than 5 times to ensure that the composition of the obtained as-cast slab is uniform.

In the present invention, during smelting, the β phase preferentially nucleates and grows in the process of transforming the smelting liquid into a solid state, and obtains a β phase green body, and obtains an α′ martensitic phase original green body after rolling, and obtains recovery and growth for subsequent annealing treatment The α′ martensitic phase body provides the basis. Moreover, the smelting process can make the components of the as-cast slab uniform, and effectively eliminate pores and defects.

Before the smelting, the alloy raw material is preferably ultrasonically cleaned in the present invention; the present invention has no special requirements for the specific implementation of the ultrasonic cleaning, and those well-known to those skilled in the art can be used. After obtaining the as-cast alloy billet, the present invention deforms the as-cast alloy billet after heat preservation treatment to obtain a densified alloy billet. In the invention, the as-cast alloy blank is subjected to heat preservation treatment before deformation treatment, so that the titanium alloy ingot can maintain a relatively high temperature during the deformation process and realize thermal deformation. The hot-rolling deformation mode adopted by the invention is beneficial to break the crystal grains, refine the structure grains, eliminate structure defects, increase the dislocation density in the microstructure, and improve the alloy strength.

In the present invention, the temperature of the heat preservation treatment is preferably 850-950°C, more preferably 905-945°C, more preferably 910-925°C; the time of the heat preservation treatment is preferably 40-60min, more preferably 50 minutes ~60min.

After the heat preservation treatment, the present invention deforms the heat preservation titanium alloy ingot to obtain a densified alloy billet. In the present invention, the deformation method is preferably rolling deformation, and the total deformation amount of the rolling deformation is preferably 40-50%, more preferably 45-48%. In the present invention, deformation treatment is carried out after heat preservation treatment, so that thermal deformation occurs, so that metastable β phase grains are refined, and a large number of dislocations are generated, which helps to improve the strong plasticity of the alloy; the present invention adopts a hot rolling method, which can Effectively eliminate casting defects, compact structure, refine grains, and the process of hot rolling can generate a large number of dislocations, which can improve the mechanical properties of the alloy in the rolling direction.

In the present invention, the rolling deformation is further preferably multi-pass rolling, and the deformation amount of each pass is preferably 15-20%; the present invention has no special requirements on the rolling times of the multi-pass rolling, It is sufficient to achieve the target deformation amount. When multi-pass rolling is carried out in the present invention, after each rolling, the present invention preferably heats the rolled alloy billet at the rolling deformation temperature for 5-10 minutes, more preferably 6-7 minutes. The present invention has no special requirements on the specific implementation of the rolling deformation, and those known to those skilled in the art can be used. The present invention adopts the mode of multi-pass rolling deformation, controls the amount of deformation in a single pass, overcomes the hot working resistance of α-titanium alloy, and realizes the refinement of grains as much as possible; and the present invention adopts rolling in separate passes, more It is conducive to the breaking and refining of matrix grains and is not easy to crack.

After the densified alloy billet is obtained, the present invention performs annealing treatment on the densified alloy billet to obtain an all-alpha-phase fine-grained high-strength toughness corrosion-resistant titanium alloy. In the present invention, the method of the annealing treatment is preferably: heating the densified alloy billet to 750-830° C. in a furnace, holding it for 30-60 minutes, and then cooling it in a furnace. In the present invention, the densified alloy billet is preferably heated to 750-830°C, more preferably 780-800°C; the holding time is preferably 30-60 minutes, more preferably 35-50 minutes, more preferably 40-45 minutes. In the present invention, the heat preservation process of the annealing treatment is preferably carried out under a protective atmosphere, and the protective atmosphere is specifically an argon protective atmosphere. In the present invention, the solution treatment can eliminate the residual stress caused by thermal deformation as much as possible, improve the plasticity, and can also reduce the temperature drop in the deformation stage during the hot rolling deformation process, so that it can be re-solutionized to α+β Two-phase state, reducing stress, during which part of the α-phase to β-phase transformation will occur, so as to ensure a certain degree of plasticity while increasing a certain strength, and better control the properties of the alloy.

In the present invention, the annealing treatment can effectively eliminate the residual stress formed in the smelting process and eliminate some microscopic defects, further homogenize the alloy composition, restore the α' martensite phase, and improve the processing performance of the alloy. It also improves the corrosion resistance of the alloy, and finally obtains an all-α-phase titanium alloy.

The invention only needs to carry out thermal deformation after smelting, and then carry out simple annealing treatment to obtain the titanium alloy with excellent strength performance, and the method is simple and easy.

After the annealing treatment, the present invention preferably removes the surface scale of the solid solution alloy to obtain a high-strength corrosion-resistant titanium alloy. In the present invention, the surface oxide scale is preferably removed by grinding.

The present invention combines the interaction between elements to provide the corrosion resistance and strength of the titanium alloy. The thermal deformation of the present invention is beneficial to break the crystal grains, further refine the grains of the structure, eliminate the defects of the structure, and improve the strength of the alloy.

In order to further illustrate the present invention, the full α-phase fine-grained high-strength and corrosion-resistant titanium alloy provided by the present invention and its preparation method are described in detail below in conjunction with examples, but they should not be construed as limiting the protection scope of the present invention.

Example 1

According to the alloy composition Ti-3Zr-2.5Al (mass percentage), take 94.5g of industrial-grade sponge titanium, 3g of sponge zirconium, and 2.5g of pure aluminum and soak them in absolute ethanol. In the water-cooled copper crucible of the vacuum arc melting ^furnace , the inner wall of the copper crucible should be cleaned and wiped clean in advance to avoid bringing in other impurities. After high-purity argon is used as the protective gas (vacuum degree is 0.04-0.05MPa), the arc temperature is about 2500°C during each melting, and the melting time is about 3 minutes each time. After each melting, the ingot is obtained by cooling. Then the ingot is turned over for smelting, so that the smelting-casting ingot is repeatedly smelted and turned over 6 times to ensure that the composition of the finally obtained ingot is uniform.

Put the alloy ingot into the muffle furnace and heat it to 950°C for 40 minutes. At this temperature, it is quickly taken out and rolled and deformed on the twin-roll mill. The rolling process adopts multi-pass rolling and deformation. The rolling of each pass The amount of deformation is 15%, and the total rolling amount is guaranteed to be 40%. Meanwhile, after each pass of rolling, it is put into a muffle furnace and heated to a corresponding rolling temperature of 950° C., and kept for 10 minutes.

After the final rolling pass, the rolled sheet was air-cooled to room temperature. Then the alloy ingot is put into a vacuum/atmosphere tube furnace (SK-G06143 Tianjin Zhonghuan Experimental Electric Furnace Co., Ltd.) for annealing treatment. The holding temperature of the annealing treatment is controlled to be 750° C., and the holding time is 120 minutes, and then cooled with the furnace to room temperature.

After the alloy plate is completely cooled, it is taken out, the oxide skin on the surface of the prepared alloy plate is polished, washed and air-dried, and finally a titanium alloy is obtained.

The metallographic structure of the titanium alloy obtained in this example was observed, and the results are shown in Figure 1. It can be seen that the titanium alloy prepared in this example is composed of thick and interlaced α laths, and the α laths recover and grow after annealing .

Example 2

According to the alloy composition Ti-10Zr-2.3Al (mass percentage), take 87.7g of industrial-grade sponge titanium, 10g of sponge zirconium, and 2.3g of pure aluminum and soak them in absolute ethanol. In the water-cooled copper crucible of the vacuum arc melting ^furnace , the inner wall of the copper crucible should be cleaned and wiped clean in advance to avoid bringing in other impurities. After high-purity argon is used as a protective gas (vacuum degree is 0.04-0.05MPa), the arc temperature is about 2600°C during each smelting, and the smelting time is about 3 minutes each time. Then the ingot is turned over for smelting, so that the smelting-casting ingot is repeatedly smelted and turned over 6 times to ensure that the composition of the finally obtained ingot is uniform.

Put the alloy ingot into the muffle furnace and heat it to 930°C for 45 minutes. At this temperature, it is quickly taken out and rolled and deformed on the twin-roll mill. The rolling process adopts multi-pass rolling and deformation. The amount of deformation is 17%, and the total rolling amount is guaranteed to be 43%. Meanwhile, after each pass of rolling, it is put into a muffle furnace and heated to a corresponding rolling temperature of 930° C., and kept for 8 minutes.

After the final rolling pass, the rolled sheet was air-cooled to room temperature. Then the alloy ingot is put into a vacuum/atmosphere tube furnace (SK-G06143 Tianjin Zhonghuan Experimental Electric Furnace Co., Ltd.) for annealing treatment. The holding temperature of the annealing treatment is controlled to be 810° C., and the holding time is 40 minutes, and then cooled with the furnace to room temperature.

After the alloy plate is completely cooled, it is taken out, the oxide skin on the surface of the prepared alloy plate is polished, washed and air-dried, and finally a titanium alloy is obtained.

The metallographic structure of the titanium alloy obtained in this example was observed, and the results are shown in Figure 2. It can be seen that the titanium alloy prepared in this example is composed of coarse and broken α laths, and the α laths recover and grow after annealing .

Example 3

According to the alloy composition Ti-25Zr-2.1Al (mass percentage), take 92.9g of industrial-grade sponge titanium, 25g of sponge zirconium, and 2.1g of pure aluminum and soak them in absolute ethanol. In the water-cooled copper crucible of the vacuum arc melting ^furnace , the inner wall of the copper crucible should be cleaned and wiped clean in advance to avoid bringing in other impurities. After high-purity argon is used as a protective gas (vacuum degree is 0.04-0.05MPa), the arc temperature is about 2600°C during each smelting, and the smelting time is about 3 minutes each time. Then the ingot is turned over for smelting, so that the smelting-casting ingot is repeatedly smelted and turned over 7 times to ensure that the finally obtained ingot has a uniform composition.

Put the alloy ingot into the muffle furnace and heat it to 900°C for 50 minutes. At this temperature, it is quickly taken out and rolled and deformed on the twin-roll mill. The rolling process adopts multi-pass rolling and deformation. The rolling of each pass The amount of deformation is 16%, and the total rolling amount is guaranteed to be 45%. Meanwhile, after each pass of rolling, it is put into a muffle furnace and heated to a corresponding rolling temperature of 900° C., and kept for 10 minutes.

After the final rolling pass, the rolled sheet was air-cooled to room temperature. Then the alloy ingot is put into a vacuum/atmosphere tube furnace (SK-G06143 Tianjin Zhonghuan Experimental Electric Furnace Co., Ltd.) for annealing treatment. The holding temperature of the annealing treatment is controlled to be 790° C., and the holding time is 45 minutes, and then cooled with the furnace to room temperature.

After the alloy plate is completely cooled, it is taken out, the oxide skin on the surface of the prepared alloy plate is polished, washed and air-dried, and finally a titanium alloy is obtained.

The metallographic structure of the titanium alloy obtained in this example is observed, and the results are shown in Figure 3. It can be seen that the titanium alloy prepared in this example is composed of thinner and interlaced α laths, and the α laths recover after annealing and grow.

Example 4

According to the alloy composition Ti-40Zr-1.9Al (mass percentage), take 58.1g of industrial-grade sponge titanium, 40g of sponge zirconium, and 1.9g of pure aluminum and soak them in absolute ethanol. In the water-cooled copper crucible of the vacuum arc melting ^furnace , the inner wall of the copper crucible should be cleaned and wiped clean in advance to avoid bringing in other impurities. After high-purity argon is used as the protective gas (vacuum degree is 0.04-0.05MPa), the arc temperature is about 2500°C during each melting, and the melting time is about 3 minutes each time. After each melting, the ingot is obtained by cooling. Then the ingot is turned over for smelting, so that the smelting-casting ingot is repeatedly smelted and turned over 7 times to ensure that the finally obtained ingot has a uniform composition.

Put the alloy ingot into a muffle furnace and heat it to 880°C for 55 minutes. At this temperature, it is quickly taken out and rolled and deformed on a twin-roll mill. The rolling process adopts multi-pass rolling and deformation. The rolling of each pass The amount of deformation is 18%, and the total rolling amount is guaranteed to be 48%. Meanwhile, after each pass of rolling, it is put into a muffle furnace and heated to a corresponding rolling temperature of 880° C., and kept for 6 minutes.

After the final rolling pass, the rolled sheet was air-cooled to room temperature. Then the alloy ingot is put into a vacuum/atmosphere tube furnace (SK-G06143 Tianjin Zhonghuan Experimental Electric Furnace Co., Ltd.) for annealing treatment, and the holding temperature of the annealing treatment is controlled to be 770° C., and the holding time is 50 minutes, and then cooled with the furnace to room temperature.

After the alloy plate is completely cooled, it is taken out, the oxide skin on the surface of the prepared alloy plate is polished, washed and air-dried, and finally a titanium alloy is obtained.

The metallographic structure of the titanium alloy obtained in this example is observed, and the results are shown in Figure 4. It can be seen that the titanium alloy prepared in this example is composed of fine and interlaced α laths, and the α laths recover and grow after annealing .

Example 5

According to the alloy composition Ti-50Zr-1.8Al (mass percentage), take 47.2g of industrial-grade sponge titanium, 50g of sponge zirconium, and 1.8g of pure aluminum and soak them in absolute ethanol. In the water-cooled copper crucible of the vacuum arc melting ^furnace , the inner wall of the copper crucible should be cleaned and wiped clean in advance to avoid bringing in other impurities. After high-purity argon is used as the protective gas (vacuum degree is 0.04-0.05MPa), the arc temperature is about 2700°C during each smelting, and the smelting time is about 2.5 minutes each time. Then the ingot is turned over for smelting, so that the smelting-casting ingot is repeatedly smelted and turned over 6 times to ensure that the composition of the finally obtained ingot is uniform.

Put the alloy ingot into a muffle furnace and heat it to 850°C for 60 minutes. At this temperature, it is quickly taken out and rolled and deformed on a two-roll mill. The rolling process adopts multi-pass rolling and deformation. The amount of deformation is 20%, and the total rolling amount is guaranteed to be 50%. Meanwhile, after each pass of rolling, it is put into a muffle furnace and heated to a corresponding rolling temperature of 850° C., and kept warm for 5 minutes.

After the final rolling pass, the rolled sheet was air-cooled to room temperature. Then the alloy ingot is put into a vacuum/atmosphere tube furnace (SK-G06143 Tianjin Zhonghuan Experimental Electric Furnace Co., Ltd.) for annealing treatment. The holding temperature of the annealing treatment is controlled to be 750° C., and the holding time is 60 minutes, and then cooled with the furnace to room temperature.

After the alloy plate is completely cooled, it is taken out, the oxide skin on the surface of the prepared alloy plate is polished, washed and air-dried, and finally a titanium alloy is obtained.

The metallographic structure of the titanium alloy obtained in this embodiment was observed, and the results are shown in FIG. 5 . It can be seen that the titanium alloy obtained in this embodiment is composed of fine interlaced α laths.

Comparative example 1

The alloy composition is Ti-2Al-2.5Zr titanium alloy prepared in the manner of Example 1.

Tensile samples (national standard: GBT228-2002) were cut out of the titanium alloys of Examples 1-5 and Comparative Example 1 by wire cutting, as shown in FIG. 6 . At least 5 tensile samples were cut out of each sample to ensure the repeatability of the data, and the room temperature uniaxial tensile test was used for measurement. The test instrument model was Instron5982 universal material testing machine (manufacturer: Instron, the United States) , the tensile displacement of the sample was monitored by an extensometer throughout the process, the tensile rate was set at 5×10 ^-3 s ^-1 , and the tensile test was carried out to obtain data related to its mechanical properties. The test results are shown in Table 1.

The mechanical property test of the titanium alloy that table 1 embodiment 1～5 and comparative example 1 obtain

As can be seen from Table 1, compared with the measured contrast titanium alloy among the titanium alloys obtained in the present invention, the mechanical property test results of the titanium alloys obtained in Examples 1 to 5 are as follows: the increase in yield strength is as high as 104.8%, and the increase in tensile strength is as high as 104.8%. As high as 94.5%, the strength has been greatly improved; and the elongation has remained at a considerable level; both yield and tensile strength have been improved, and the plasticity has a small decrease, and the strength and toughness have been improved.

Simultaneously the titanium alloy that embodiment 1～5 and comparison alloy are made respectively cuts out the salt spray test sample that size is 10mm * 10mm * 2mm with wire cutting, and every alloy ingot cuts out 5 samples, guarantees the reliability of experiment Repeatability; take the 10mm×10mm surface as the tested surface, use phenolic plastic powder to seal the other non-tested surfaces in the metallographic test mounting machine (XQ-1, Shanghai Metallographic Machinery Equipment Co., Ltd.), and will be tested after taking it out. The test surface is polished to 3000# with sandpaper, and then cleaned and dried. Based on GB/T 10125-1997, the neutral salt spray test is carried out in the environment of 5% sodium chloride solution. According to the standard The sample is cleaned, weighed, placed, observed and maintained and adjusted on the salt spray test machine (BY-120A, Beijing Boyu Xiangda Instrument Co., Ltd.) in sequence. The test period is 1440 hours (two months), The parameters of the test conditions are shown in Table 2, from which the data related to its corrosion performance are obtained, and the test results are shown in Table 3.

Table 2 Salt spray test test standard of the present invention

The corrosion resistance test test result of the titanium alloy that table 3 embodiment 1～5 and comparative example 1 obtain

As can be seen from Table 2, in the present invention, the increase of Zr content makes its anti-corrosion property more excellent, compares with the comparison alloy (Ti-2Al-2.5Zr) that same treatment process obtains, and the anti-corrosion ability in sodium chloride solution The boost is as high as 59.85%.

It can be seen from the above examples that the neutral element Zr, which has little influence on the phase transition temperature, forms an infinite solid solution with Ti through alloying in the present invention, thereby realizing solid solution strengthening, and the passivation potential of Zr is more negative than that of Ti, even if Passivation can still occur in the environment of weak oxidation conditions, which improves the ability to form a dense oxide film on the surface and improves its corrosion resistance. And the titanium alloy prepared by the present invention recovers and grows after the annealing, and the α laths are all composed of the α' martensite phase of the basket-shaped laths.

Moreover, the preparation process of the titanium alloy of the present invention is simple, the production cost is low, it is very convenient for industrial production, the cost is low, and the operation process is simple; by controlling the content of each element, the mechanical properties of the titanium alloy are improved, and the strength of the titanium alloy is significantly improved, so that it meets Requirements for aerospace components.

The above descriptions are only preferred embodiments of the present invention, and do not limit the present invention in any form. It should be pointed out that those skilled in the art can make some improvements and modifications without departing from the principle of the present invention, and these improvements and modifications should also be regarded as the protection scope of the present invention.

Claims (10)

1. An all-α-phase fine-grained high-strength, tough, and corrosion-resistant titanium alloy, comprising 1.8 to 2.5% of Al, 5 to 50% of Zr and the remainder of Ti by mass content; Titanium alloys do not contain Pd. 2. The all-α-phase fine-grained high-strength and corrosion-resistant titanium alloy according to claim 1, characterized in that the all-α-phase fine-grained high-strength and corrosion-resistant titanium alloy comprises 2.2-2.5% of Al and 10-40% of Zr and the remainder of Ti. 3. The all-α-phase fine-grained high-strength, tough, and corrosion-resistant titanium alloy according to claim 1 or 2, wherein the all-α-phase fine-grained, high-strength, and corrosion-resistant titanium alloy consists of a basket-like α′ martensitic phase Lath composition: the average width of the α' phase lath in the structure of the high-strength and toughness corrosion-resistant titanium alloy is 24.23-79.41 μm. 4. The method for preparing the all-α-phase fine-grained high-strength and corrosion-resistant titanium alloy according to any one of claims 1 to 3, characterized in that it comprises the following steps: (1) Obtain the as-cast alloy billet after melting the alloy raw material; (2) deforming the as-cast alloy billet obtained in the step (1) after heat preservation treatment to obtain a densified alloy billet; (3) Annealing the densified alloy billet obtained in the step (2) to obtain an all-alpha-phase fine-grained high-strength and tough corrosion-resistant titanium alloy. 5. The preparation method according to claim 4, characterized in that the melting in the step (1) is vacuum arc melting, and the temperature of the vacuum arc melting is 2500-3000°C. 6 . The preparation method according to claim 4 or 5 , characterized in that, the number of smelting in the step (1) is more than 5 times, and each smelting time is 3-5 minutes. 7. The preparation method according to claim 4, characterized in that, the temperature of the heat preservation treatment in the step (2) is 850-950° C., and the time is 40-60 minutes. 8. The preparation method according to claim 4, characterized in that, the deformation in the step (2) is rolling deformation; the total deformation of the rolling deformation is 40-50%. 9. The preparation method according to claim 8, characterized in that the rolling deformation is multi-pass rolling, and the deformation of each pass is 15-20%; When multi-pass rolling is adopted, after each pass of rolling, the rolled alloy billet is kept at the temperature of heat preservation treatment for 5-10 minutes. 10. The preparation method according to claim 4, characterized in that, the annealing method in the step (3) is: heating the densified alloy billet to 750-830°C with the furnace and then keeping it warm for 30-60 minutes, Then cool with the furnace.