A cast titanium alloy material resistant to seawater erosion corrosion and a preparation method thereof

Abstract

The application provides a cast titanium alloy material resistant to seawater scouring corrosion and a preparation method thereof, and relates to the technical field of cast titanium alloy materials.The chemical composition of the alloy material according to the application comprises, in percentage by mass, 5.8-6.5% of Al, 3.8-4.5% of V, 0.8-1.5% of Zr, 0.8-1.5% of Nb, 0.1-0.3% of O, 0.2-0.5% of Fe, and the rest is Ti.The preparation method comprises the following steps: mixing raw materials of titanium sponge, Al beans, AlV 58 , TiFe 32 , TiO2 powder, AlNb 70 powder and zirconium sponge, and then pressing the mixture into electrode blocks; assembling the electrode blocks into long-stripe electrodes; performing multiple melting on the long-stripe electrodes and pouring to obtain alloy samples; taking out the alloy samples after cooling after pouring, and performing hot isostatic pressing to obtain titanium alloy samples.In the application, by adding zirconium elements, niobium elements, and trace amounts of oxygen elements and iron elements into the titanium alloy, the seawater scouring corrosion resistance of the titanium alloy is greatly improved, and the design and manufacturing requirements of large ship parts subjected to seawater scouring are met.

Description

Technical Field

[0001] This invention belongs to the technical field of cast titanium alloy materials, specifically relating to a cast titanium alloy material resistant to seawater erosion and corrosion and its preparation method. Background Technology

[0002] Titanium alloy castings are widely used in aerospace, marine engineering, shipbuilding, and petrochemical industries due to their excellent mechanical properties, low density, superior corrosion resistance, and relatively low processing costs. In recent years, stainless steel components in large marine equipment have been gradually replaced by pure titanium, Ti-6Al-4V, and other titanium alloys. Developing titanium alloy materials with superior strength-ductility matching, seawater corrosion resistance, and good casting process performance is of great significance for improving the reliability and durability of complex components in marine engineering fields such as shipbuilding.

[0003] Among the commonly used cast titanium alloys in marine applications, Ti-6Al-4V alloy exhibits the best overall mechanical properties. Some reports mention a new type of low-cost, high-ductility, seawater-corrosion-resistant titanium alloy. By weight percentage, this alloy's chemical composition is: Al 3.0%–4.5%, V 2.0%–3.0%, Fe 0.5%–1.5%, Cu 0.5%–2.0%, with the balance being Ti and unavoidable impurity elements. By adding Fe and Cu, this alloy achieves higher seawater corrosion resistance than Ti-6Al-4V alloy. However, a drawback of this approach is that without subsequent heat treatment for strengthening, the yield strength of this alloy only reaches 660 MPa, representing a significant sacrifice in strength compared to Ti-6Al-4V alloy. Summary of the Invention

[0004] To address the problems existing in the prior art, this invention, based on the widely used Ti-6Al-4V casting titanium alloy composition with excellent fluidity, introduces small amounts of Nb and Zr. This improves the alloy's resistance to seawater erosion corrosion while maintaining its excellent casting properties. This improvement not only extends the alloy's service life in marine environments but also enhances its reliability and stability in complex marine environments. Furthermore, the casting process performance of this alloy is comparable to that of the Ti-6Al-4V alloy, avoiding complex process steps and making it suitable for low-cost manufacturing of large load-bearing marine components such as rotor blades.

[0005] Specifically, the first aspect of the present invention provides a cast titanium alloy material resistant to seawater erosion and corrosion. The chemical composition of the alloy material, by mass percentage, includes 5.8%–6.5% Al, 3.8%–4.5% V, 0.8%–1.5% Zr, 0.8%–1.5% Nb, 0.1%–0.3% O, 0.2%–0.5% Fe, with the remainder being Ti.

[0006] A second aspect of the present invention provides a method for preparing the above-mentioned seawater erosion-resistant cast titanium alloy material, the method comprising the following steps:

[0007] S1, with sponge titanium, Al beans, AlV 58 TiFe 32 , TiO2 powder, AlNb 70 Powder and sponge zirconium are used as raw materials. They are weighed and mixed according to the chemical composition ratio of the alloy material described in claim 1 to obtain a mixture. Then, the mixture is pressed into an electrode block by a press and a mold.

[0008] S2. Weld the electrode blocks together into a long strip electrode;

[0009] S3. The long strip electrode obtained in step S2 is melted and cast multiple times to obtain an alloy sample;

[0010] S4. After casting is completed, the alloy sample is removed from the furnace after cooling.

[0011] S5. The alloy sample obtained in step S4 is subjected to hot isostatic pressing to obtain the final cast titanium alloy sample resistant to seawater erosion corrosion.

[0012] As a further explanation of the present invention, the melting process in step S3 is first completed in a vacuum consumable electrode arc melting furnace, and the resulting primary ingot is cast in a cold crucible suspension melting furnace or a vacuum solidification furnace.

[0013] As a further explanation of the present invention, the hot isostatic pressing parameters for step S5 are as follows: temperature is 910℃~930℃, pressure is 110~130MPa, and time is 2~4h.

[0014] Compared with the prior art, the present invention has the following beneficial technical effects:

[0015] This invention involves adding zirconium, niobium, and trace amounts of oxygen and iron to a titanium alloy, while controlling the mass percentages of Zr (0.8%–1.5%), Nb (0.8%–1.5%), O (0.1%–0.3%), and Fe (0.2%–0.5%). This alloy exhibits significantly improved resistance to seawater erosion corrosion compared to the Ti-6Al-4V alloy, meeting the design and manufacturing requirements of large ship components subjected to seawater erosion.

[0016] The alloy of this invention exhibits a significantly reduced corrosion rate under seawater erosion at a flow rate of 10 m / s. Simultaneously, the room-temperature mechanical properties of this alloy remain consistent with those of Ti-6Al-4V. Specific performance parameters are: yield strength 750–780 MPa, tensile strength 835–870 MPa, elongation 13%–15%; seawater erosion corrosion rate ≤0.0033 mm / a. This improved Ti-6Al-4V titanium alloy significantly enhances corrosion resistance, thereby extending the service life of marine equipment and reducing the operating costs of related devices.

[0017] Other features and advantages of this technical solution will be set forth in the following description, and will be apparent in part from the description, or may be learned by practicing the technical solution. The objectives and other advantages of this technical solution can be realized and obtained by means of the structures particularly pointed out in the written description and the accompanying drawings.

[0018] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0019] The accompanying drawings are provided to further understand the present technical solution and form part of the specification. They are used together with the embodiments of the present technical solution to explain the present technical solution and do not constitute a limitation on the present technical solution.

[0020] Figure 1 This is a diagram of the alloy microstructure of an embodiment of the present invention.

[0021] Figure 2 This is a rod-shaped tensile specimen used for room temperature tensile property testing in this invention.

[0022] Figure 3 This is a sheet-like erosion specimen used for testing the seawater erosion corrosion resistance of this invention.

[0023] Figure 4 This is the casting and filling situation of Embodiment 1 of the present invention.

[0024] Figure 5 This is the casting and filling situation for Comparative Example 1.

[0025] Figure 6This is a tensile stress-strain curve diagram of embodiment 2 of the present invention.

[0026] Figure 7 This is a tensile stress-strain curve diagram of embodiment 3 of the present invention.

[0027] Figure 8 This is a tensile stress-strain curve diagram of embodiment 4 of the present invention.

[0028] Figure 9 The image shows the stress-strain tensile curve for comparative example 2. Detailed Implementation

[0029] The preferred embodiments of this technical solution are described below with reference to the accompanying drawings. It should be understood that the preferred embodiments described herein are only for illustration and explanation of this technical solution and are not intended to limit this technical solution.

[0030] Among the titanium alloys commonly used in marine applications, TA2, TA5, and ZTi60 (Ti-2.5Al-2.5Mo-1Zr) exhibit good casting properties and excellent resistance to seawater corrosion. However, their yield strength is generally at or below 600 MPa, which cannot meet the performance requirements for manufacturing high-load-bearing components. Some literature reports that adding Fe and Cu elements can achieve higher seawater corrosion resistance than Ti-6Al-4V alloys. However, the drawback of this method is that without subsequent heat treatment strengthening, the yield strength of this alloy can only reach 660 MPa, sacrificing a significant amount of strength compared to Ti-6Al-4V alloys.

[0031] To address the aforementioned technical problems, the first aspect of this invention provides a cast titanium alloy material resistant to seawater erosion and corrosion. The chemical composition of the alloy material, by mass percentage, includes 5.8%–6.5% Al, 3.8%–4.5% V, 0.8%–1.5% Zr, 0.8%–1.5% Nb, 0.1%–0.3% O, 0.2%–0.5% Fe, with the remainder being Ti.

[0032] By mass percentage, the Al content can be, for example, 5.8%, 6%, 6.2%, 6.4%, 6.5%; the V content can be, for example, 3.8%, 4%, 4.2%, 4.4%, 4.5%; the Zr content can be, for example, 0.8%, 1%, 1.2%, 1.3%, 1.5%; the Nb content can be, for example, 0.8%, 1%, 1.2%, 1.3%, 1.5%; the O content can be, for example, 0.1%, 0.2%, 0.3%; and the Fe content can be, for example, 0.2%, 0.3%, 0.4%, 0.5%.

[0033] This invention involves adding zirconium, niobium, and trace amounts of oxygen and iron to a titanium alloy, while controlling the mass percentages of Zr (0.8%–1.5%), Nb (0.8%–1.5%), O (0.1%–0.3%), and Fe (0.2%–0.5%). This alloy exhibits significantly improved resistance to seawater erosion corrosion compared to the Ti-6Al-4V alloy, meeting the design and manufacturing requirements of large ship components subjected to seawater erosion.

[0034] The present invention also provides a method for preparing the above-mentioned seawater erosion corrosion resistant cast titanium alloy material, the method comprising the following steps:

[0035] S1, with sponge titanium, Al beans, AlV 58 TiFe 32 , TiO2 powder, AlNb 70 Powdered zirconium sponge is used as raw material. After weighing and mixing according to the chemical composition ratio of the alloy material described in claim 1, a mixture is obtained. Then, the mixture is pressed into electrode blocks by a press and a mold.

[0036] S2. The electrode blocks are welded into long strip electrodes.

[0037] S3. The long strip electrode obtained in step S2 is melted and cast multiple times to obtain an alloy sample;

[0038] Specifically, the above-mentioned smelting process is first completed in a vacuum consumable electrode arc smelting furnace, and the resulting primary ingot is cast in a cold crucible suspension smelting furnace or a vacuum solidification furnace.

[0039] S4. After casting is completed, the alloy sample is removed from the furnace after cooling.

[0040] S5. The alloy sample obtained in step S4 is subjected to hot isostatic pressing to obtain the final cast titanium alloy sample resistant to seawater erosion corrosion.

[0041] Specifically, the hot isostatic pressing parameters for step S5 are as follows: temperature is 910℃~930℃, for example, it can be set to 910℃, 915℃, 920℃, 925℃, 930℃, etc.; pressure is 110~130MPa, for example, it can be set to 110MPa, 115MPa, 120MPa, 125MPa, 130MPa, etc.; time is 2~4h, for example, it can be set to 2h, 2.5h, 3h, 3.5h, 4h, etc.

[0042] The following is an explanation with reference to specific embodiments: Example 1

[0043] Step 1: Combine sponge titanium, Al beans, and AlV 58TiFe 32 , TiO2 powder, AlNb 70 Powdered and sponge zirconium raw materials are mixed and pressed into electrode blocks;

[0044] Step 2: Weld the electrode blocks obtained in Step 1 into long strip electrodes;

[0045] Step 3: The long strip electrode is used as a consumable electrode and melted in a vacuum consumable electrode arc melting furnace to obtain a primary ingot, which is then poured in a cold crucible suspension melting furnace and removed from the furnace after cooling.

[0046] The main components of the ingot, by mass percentage, are: Al: 6.16%, V: 4.06%, Zr: 1.02%; Nb: 0.97%; Fe: 0.32%; O: 0.12%, with the remainder being titanium. The mold used was a 150mm high, plum-shaped column. During the casting process, the alloy exhibited good fluidity, and the mold filled completely, as shown in the following figures. Figure 4 Comparison with TC4 component filling ( Figure 5 They have the same filling capacity. Example 2

[0047] Step 1: Combine sponge titanium, Al beans, and AlV 58 TiFe 32 , TiO2 powder, AlNb 70 Powdered and sponge zirconium raw materials are mixed and pressed into electrode blocks;

[0048] Step 2: Weld the electrode blocks obtained in Step 1 into long strip electrodes;

[0049] Step 3: The long strip electrode is used as a consumable electrode in a vacuum consumable electrode arc melting furnace to obtain a primary ingot. The primary ingot is used as a consumable electrode in a cold crucible suspension melting furnace for casting. After cooling, it is taken out of the furnace.

[0050] Step 4: The obtained standard sample casting is subjected to hot isostatic pressing at 920℃ / 130MPa for 3 hours.

[0051] The alloy structure is lamellar, such as Figure 1 The main components by mass percentage are: Al: 6.16%, V: 4.06%, Zr: 1.02%; Nb: 0.97%; Fe: 0.32%; O: 0.12%, with the remainder being titanium. A round bar with a diameter of 11mm was cut from the casting and machined as shown. Figure 2 The tensile test bar of M10 shown was tested using an electronic universal testing machine, and the room temperature mechanical properties were: yield strength 779 MPa, tensile strength 869 MPa, elongation 15%. The engineering stress-strain curve is shown below. Figure 6 Cut out such as in the casting Figure 3The erosion test piece shown was fixed with a hole in the center and the surface was polished. The corrosion rate was measured for 30 days in a natural seawater environment with a flow rate of 10 m / s using a rotating erosion corrosion device, and the result was 0.0021 mm / a. Example 3

[0052] Step 1: Combine sponge titanium, Al beans, and AlV 58 TiFe 32 , TiO2 powder, AlNb 70 Powdered and sponge zirconium raw materials are mixed and pressed into electrode blocks;

[0053] Step 2: Weld the electrode blocks obtained in Step 1 into long strip electrodes;

[0054] Step 3: The long strip electrode is used as a consumable electrode in a vacuum consumable electrode arc melting furnace to obtain a primary ingot. The primary ingot is used as a consumable electrode in a cold crucible suspension melting furnace for casting. After cooling, it is taken out of the furnace.

[0055] Step 4: The obtained standard sample casting is subjected to hot isostatic pressing at 920℃ / 130MPa for 2 hours.

[0056] The main alloy components by mass percentage are: Al: 6.20%, V: 4.05%, Zr: 1.03%; Nb: 0.94%; Fe: 0.34%; O: 0.11%, with the remainder being titanium. A round bar with a diameter of 11 mm is cut from a standard casting and machined as follows... Figure 2 The tensile test bar of M10 shown was tested using an electronic universal testing machine, and the room temperature mechanical properties were: yield strength 757 MPa, tensile strength 836 MPa, elongation 14%. The engineering stress-strain curve is shown below. Figure 7 Cut out such as in the casting Figure 3 The erosion test piece shown was fixed with a hole in the center and the surface was polished. It was tested for 30 days in a natural seawater environment with a flow rate of 10 m / s using a rotating erosion corrosion device, and the corrosion rate was found to be 0.0031 mm / a. Example 4

[0057] Step 1: Combine sponge titanium, Al beans, and AlV 58 TiFe 32 , TiO2 powder, AlNb 70 Powdered and sponge zirconium raw materials are mixed and pressed into electrode blocks;

[0058] Step 2: Weld the electrode blocks obtained in Step 1 into long strip electrodes;

[0059] Step 3: Melt the long strip electrode in a vacuum consumable electrode arc melting furnace, then cast it in a vacuum solidification furnace, and remove it from the furnace after cooling.

[0060] Step 4: The obtained standard sample casting is subjected to hot isostatic pressing at 920℃ / 130MPa for 3 hours.

[0061] The main alloy components by mass percentage are: Al: 6.16%, V: 4.11%, Zr: 1.01%; Nb: 0.95%; Fe: 0.32%; O: 0.15%, with the remainder being titanium. A round bar with a diameter of 11 mm is cut from the casting, and then machined as shown... Figure 2 The tensile test bar of M10 shown was tested using an electronic universal testing machine, and the room temperature mechanical properties were: yield strength 754 MPa, tensile strength 838 MPa, elongation 13%. The engineering stress-strain curve is shown below. Figure 8 Cut out such as in the casting Figure 3 The erosion test piece shown was fixed with a hole in the center and the surface was polished. The corrosion rate was measured for 30 days in a natural seawater environment with a flow rate of 10 m / s using a rotating erosion corrosion device, and the result was 0.0033 mm / a.

[0062] Comparative Example 1

[0063] Step 1: Combine sponge titanium, Al beans, and AlV 58 TiFe 32 TiO2 powder is mixed and then pressed into electrode blocks;

[0064] Step 2: Weld the electrode blocks obtained in Step 1 into long strip electrodes;

[0065] Step 3: The long strip electrode is used as a consumable electrode and melted in a vacuum consumable electrode arc melting furnace to obtain a primary ingot, which is then poured in a cold crucible suspension melting furnace and removed from the furnace after cooling.

[0066] The main components of the ingot, by mass percentage, are: Al: 5.95%; V: 4.00%; Fe: 0.43%; O: 0.12%, with the remainder being titanium. The mold used was a 150mm high, plum-shaped column. During the casting process, the alloy exhibited good fluidity, and the mold filled completely, as shown in the following figures. Figure 5 .

[0067] Comparative Example 2

[0068] Step 1: Combine sponge titanium, Al beans, and AlV 58 TiFe 32 TiO2 powder is mixed and then pressed into electrode blocks;

[0069] Step 2: Weld the electrode blocks obtained in Step 1 into long strip electrodes;

[0070] Step 3: The electrode is used as a consumable electrode in a vacuum consumable electrode arc melting furnace to obtain a primary ingot. The primary ingot is used as a consumable electrode in a cold crucible suspension melting furnace for casting. After cooling, it is taken out of the furnace.

[0071] Step 4: The obtained standard sample casting is subjected to hot isostatic pressing at 920℃ / 130MPa for 3 hours.

[0072] The main alloy components by mass percentage are: Al: 5.95%; V: 4.00%; Fe: 0.43%; O: 0.12%, with the remainder being titanium. A round bar with a diameter of 11 mm is cut from the casting and machined as shown. Figure 2 The tensile test bar of M10 shown was tested using an electronic universal testing machine, and the room temperature mechanical properties were: yield strength 749 MPa, tensile strength 822 MPa, elongation 14%. The engineering stress-strain curve is shown below. Figure 9 Cut out such as in the casting Figure 3 The erosion test piece shown was drilled with a fixing hole in the center and the surface was polished. The corrosion rate was measured for 30 days in a natural seawater environment with a flow rate of 10 m / s using a rotating erosion corrosion device, and the result was 0.0042 mm / a.

[0073] from Figure 6-9 The stress-strain tensile curve of the alloy in the figure shows that the room temperature mechanical properties of the alloy of the present invention are consistent with those of Ti-6Al-4V. The specific performance parameters are: yield strength 750-780 MPa, tensile strength 835-870 MPa, and elongation 13%-15%.

[0074] Obviously, those skilled in the art can make various modifications and variations to this technical solution without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this technical solution and their equivalents, this technical solution also intends to include these modifications and variations.

Claims

1. A cast titanium alloy material resistant to seawater erosion and corrosion, characterized in that, The chemical composition of the alloy material, by mass percentage, includes 5.8%–6.5% Al, 4.11%–4.5% V, 0.8%–1.5% Zr, 0.8%–1.5% Nb, 0.1%–0.3% O, 0.32%–0.5% Fe, with the remainder being Ti; The alloy material has a yield strength of 750–780 MPa, a tensile strength of 835–870 MPa, and an elongation of 13%–15%; its corrosion rate under seawater scouring at a flow rate of 10 m / s is ≤0.0033 mm / a.

2. A method for preparing a cast titanium alloy material resistant to seawater erosion corrosion as described in claim 1, characterized in that, The method includes the following steps: S1. Using sponge titanium, Al bean, AlV58, TiFe32, TiO2 powder, AlNb70 powder, and sponge zirconium as raw materials, the materials are weighed and mixed according to the chemical composition ratio of the alloy material described in claim 1 to obtain a mixture. Then, the mixture is pressed into an electrode block using a press and a mold. S2. Weld the electrode blocks together to form a long strip electrode; S3. The long strip electrode obtained in step S2 is melted and cast multiple times to obtain an alloy sample. S4. After casting is completed, the alloy sample is removed from the furnace after cooling. S5. The alloy sample obtained in step S4 is subjected to hot isostatic pressing to obtain the final cast titanium alloy sample resistant to seawater erosion corrosion.

3. The method for preparing the seawater-resistant cast titanium alloy material as described in claim 2, characterized in that, The smelting process in step S3 is first completed in a vacuum consumable electrode arc furnace, and the resulting primary ingot is cast in a cold crucible suspension furnace or a vacuum solidification furnace.

4. The method for preparing the seawater-resistant cast titanium alloy material as described in claim 2, characterized in that, The hot isostatic pressing parameters for step S5 are as follows: temperature 910℃~930℃, pressure 110~130MPa, and time 2~4h.

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