CN116574939A - High-strength titanium alloy and preparation method thereof - Google Patents
High-strength titanium alloy and preparation method thereof Download PDFInfo
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- 229910001069 Ti alloy Inorganic materials 0.000 title claims abstract description 65
- 238000002360 preparation method Methods 0.000 title abstract description 13
- 229910052706 scandium Inorganic materials 0.000 claims abstract description 44
- SIXSYDAISGFNSX-UHFFFAOYSA-N scandium atom Chemical compound [Sc] SIXSYDAISGFNSX-UHFFFAOYSA-N 0.000 claims abstract description 44
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 claims abstract description 29
- 229910052710 silicon Inorganic materials 0.000 claims abstract description 29
- 239000010936 titanium Substances 0.000 claims abstract description 29
- 229910052719 titanium Inorganic materials 0.000 claims abstract description 29
- 239000010703 silicon Substances 0.000 claims abstract description 28
- 229910052765 Lutetium Inorganic materials 0.000 claims abstract description 24
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 claims abstract description 24
- OHSVLFRHMCKCQY-UHFFFAOYSA-N lutetium atom Chemical compound [Lu] OHSVLFRHMCKCQY-UHFFFAOYSA-N 0.000 claims abstract description 22
- 239000012535 impurity Substances 0.000 claims abstract description 5
- 238000005096 rolling process Methods 0.000 claims description 75
- 238000005242 forging Methods 0.000 claims description 32
- 238000010438 heat treatment Methods 0.000 claims description 24
- 238000005098 hot rolling Methods 0.000 claims description 15
- 238000003723 Smelting Methods 0.000 claims description 11
- 238000000137 annealing Methods 0.000 claims description 9
- 230000001186 cumulative effect Effects 0.000 claims description 9
- 238000004519 manufacturing process Methods 0.000 claims description 8
- 238000005520 cutting process Methods 0.000 claims description 6
- 238000007599 discharging Methods 0.000 claims description 6
- 238000005266 casting Methods 0.000 claims description 3
- 238000001816 cooling Methods 0.000 claims description 3
- 230000009467 reduction Effects 0.000 claims description 3
- 238000010409 ironing Methods 0.000 claims 1
- 238000002844 melting Methods 0.000 claims 1
- 230000008018 melting Effects 0.000 claims 1
- 229910045601 alloy Inorganic materials 0.000 abstract description 32
- 239000000956 alloy Substances 0.000 abstract description 32
- 238000005728 strengthening Methods 0.000 abstract description 12
- 230000000694 effects Effects 0.000 abstract description 10
- 239000011159 matrix material Substances 0.000 abstract description 8
- 238000005204 segregation Methods 0.000 abstract description 6
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 abstract description 2
- 229910052760 oxygen Inorganic materials 0.000 abstract description 2
- 239000001301 oxygen Substances 0.000 abstract description 2
- 239000002245 particle Substances 0.000 abstract description 2
- 239000007787 solid Substances 0.000 abstract 1
- 238000000034 method Methods 0.000 description 26
- 230000000052 comparative effect Effects 0.000 description 22
- 239000000463 material Substances 0.000 description 13
- 230000008569 process Effects 0.000 description 12
- 239000013078 crystal Substances 0.000 description 8
- 238000001953 recrystallisation Methods 0.000 description 8
- 238000010304 firing Methods 0.000 description 7
- 239000000203 mixture Substances 0.000 description 7
- 230000002195 synergetic effect Effects 0.000 description 5
- 238000005275 alloying Methods 0.000 description 4
- 239000006104 solid solution Substances 0.000 description 4
- 238000005516 engineering process Methods 0.000 description 3
- 239000002159 nanocrystal Substances 0.000 description 3
- 229910000831 Steel Inorganic materials 0.000 description 2
- 239000000155 melt Substances 0.000 description 2
- 229910052751 metal Inorganic materials 0.000 description 2
- 239000002184 metal Substances 0.000 description 2
- 238000007670 refining Methods 0.000 description 2
- 239000010959 steel Substances 0.000 description 2
- 238000012360 testing method Methods 0.000 description 2
- 235000015842 Hesperis Nutrition 0.000 description 1
- 235000012633 Iberis amara Nutrition 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000005540 biological transmission Effects 0.000 description 1
- 238000012512 characterization method Methods 0.000 description 1
- 238000005260 corrosion Methods 0.000 description 1
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Classifications
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C14/00—Alloys based on titanium
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21B—ROLLING OF METAL
- B21B1/00—Metal-rolling methods or mills for making semi-finished products of solid or profiled cross-section; Sequence of operations in milling trains; Layout of rolling-mill plant, e.g. grouping of stands; Succession of passes or of sectional pass alternations
- B21B1/38—Metal-rolling methods or mills for making semi-finished products of solid or profiled cross-section; Sequence of operations in milling trains; Layout of rolling-mill plant, e.g. grouping of stands; Succession of passes or of sectional pass alternations for rolling sheets of limited length, e.g. folded sheets, superimposed sheets, pack rolling
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21B—ROLLING OF METAL
- B21B37/00—Control devices or methods specially adapted for metal-rolling mills or the work produced thereby
- B21B37/16—Control of thickness, width, diameter or other transverse dimensions
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21B—ROLLING OF METAL
- B21B37/00—Control devices or methods specially adapted for metal-rolling mills or the work produced thereby
- B21B37/46—Roll speed or drive motor control
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21J—FORGING; HAMMERING; PRESSING METAL; RIVETING; FORGE FURNACES
- B21J5/00—Methods for forging, hammering, or pressing; Special equipment or accessories therefor
- B21J5/06—Methods for forging, hammering, or pressing; Special equipment or accessories therefor for performing particular operations
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21J—FORGING; HAMMERING; PRESSING METAL; RIVETING; FORGE FURNACES
- B21J5/00—Methods for forging, hammering, or pressing; Special equipment or accessories therefor
- B21J5/06—Methods for forging, hammering, or pressing; Special equipment or accessories therefor for performing particular operations
- B21J5/08—Upsetting
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B82—NANOTECHNOLOGY
- B82Y—SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
- B82Y40/00—Manufacture or treatment of nanostructures
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
- C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
- C21D8/0221—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the working steps
- C21D8/0226—Hot rolling
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
- C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
- C21D8/0247—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the heat treatment
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C1/00—Making non-ferrous alloys
- C22C1/02—Making non-ferrous alloys by melting
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22F—CHANGING THE PHYSICAL STRUCTURE OF NON-FERROUS METALS AND NON-FERROUS ALLOYS
- C22F1/00—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working
- C22F1/16—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working of other metals or alloys based thereon
- C22F1/18—High-melting or refractory metals or alloys based thereon
- C22F1/183—High-melting or refractory metals or alloys based thereon of titanium or alloys based thereon
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21B—ROLLING OF METAL
- B21B1/00—Metal-rolling methods or mills for making semi-finished products of solid or profiled cross-section; Sequence of operations in milling trains; Layout of rolling-mill plant, e.g. grouping of stands; Succession of passes or of sectional pass alternations
- B21B1/38—Metal-rolling methods or mills for making semi-finished products of solid or profiled cross-section; Sequence of operations in milling trains; Layout of rolling-mill plant, e.g. grouping of stands; Succession of passes or of sectional pass alternations for rolling sheets of limited length, e.g. folded sheets, superimposed sheets, pack rolling
- B21B2001/386—Plates
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Abstract
The invention belongs to the technical field of titanium alloy, and particularly relates to a high-strength titanium alloy and a preparation method thereof. The invention provides a high-strength titanium alloy, which comprises the following components: 0.01 to 0.3 percent of silicon, 0.01 to 0.49 percent of scandium and 0.01 to 0.49 percent of lutetium, and the balance of titanium and unavoidable impurities in percentage by mass. The alloy is characterized in that a proper amount of silicon, scandium and lutetium elements are added into a titanium matrix, the silicon and scandium elements can be dissolved into the matrix in a solid manner, the strengthening effect is achieved on titanium and titanium alloy, oxide particles can be formed with oxygen elements in melt, and creep property of the matrix is strengthened; in addition, the added lutetium element can reduce grain boundary segregation of scandium element, and has great strengthening effect on titanium alloy.
Description
Technical Field
The invention belongs to the technical field of titanium alloy, and particularly relates to a high-strength titanium alloy and a preparation method thereof.
Background
Pure titanium has the advantages of high specific strength, fatigue resistance, good corrosion resistance, good biocompatibility and the like, and is widely applied to various fields of aeroengines, rockets, missiles and the like. But compared with titanium alloy and other common engineering structural materials such as automobile steel, die steel, stainless steel and the like, the pure titanium has lower strength and lower recrystallization temperature, and limits the application field.
High alloying is a traditional idea of strengthening pure titanium, but on one hand, the high alloying can greatly increase the material raw material cost, on the other hand, the processing difficulty of the material is increased, and the comprehensive cost is greatly increased. The fine-grain strengthening is a thought of pure titanium strengthening, particularly is refined to nano-scale, can greatly strengthen the mechanical property of metal, and the severe plastic deformation technology can obviously refine metal grains to submicron and nano-scale, so that the method is considered as one of the most effective technologies for preparing bulk nano materials. However, the severe plastic deformation technology pursues high-proportion nanocrystalline, the material needs to be subjected to ultra-large deformation, the prepared sample is small in size, the requirement on equipment is high, and the method is not popularized in industrial production. Besides being used in a normal room-temperature working environment, pure titanium can also be used in a high-temperature environment of hundreds of DEG C, and nano crystal grains with high volume content prepared by severe plastic deformation are easy to recover and re-crystallize to grow up, so that the material performance is greatly reduced, and the material fails.
Therefore, the development of the process for preparing the titanium material with low equipment requirement, high strength, good plasticity, good heat resistance and low cost has important significance.
Disclosure of Invention
The present invention has been made based on the findings and knowledge of the inventors regarding the following facts and problems:
the silicon and scandium elements have a certain gain effect on the titanium and the titanium alloy, on one hand, the silicon and scandium elements can be dissolved in the matrix to strengthen the titanium and the titanium alloy, on the other hand, the silicon and scandium elements can purify the melt to reduce the behavior of titanium inclusion, meanwhile, the silicon and scandium elements and oxygen elements in the melt can form oxide particles to strengthen the creep property of the matrix, but the scandium elements have the problem of grain boundary segregation, which is not beneficial to the improvement of the strength of the titanium alloy. Moreover, the existing preparation process of the titanium alloy cannot effectively improve the strength and plasticity of the titanium alloy, so that the titanium alloy and the preparation process thereof are necessary to be studied in depth.
The present invention aims to solve at least one of the technical problems in the related art to some extent. Therefore, the embodiment of the invention provides the high-strength titanium alloy and the preparation method thereof, and the alloy is prepared by adding a proper amount of silicon, scandium and lutetium elements into a titanium matrix, so that the grain boundary segregation of scandium elements is effectively reduced, the strength of the titanium alloy is improved, and the prepared titanium alloy has better plasticity.
The high-strength titanium alloy comprises 0.01-0.3% of silicon, 0.01-0.49% of scandium and 0.01-0.49% of lutetium, and the balance of titanium and unavoidable impurities in percentage by mass.
The high-strength titanium alloy provided by the embodiment of the invention has the advantages and technical effects that 1, in the embodiment of the invention, the recrystallization temperature, high-temperature strength and structural stability of the titanium alloy can be effectively improved by adding the trace scandium element; 2. in the embodiment of the invention, the silicon element and the scandium element are added into the alloy simultaneously, and can form solid solution or precipitated phase in the matrix, so that on one hand, the growth of titanium grains can be prevented, the proportion of nanocrystals in the product is increased to about 75%, the comprehensive performance of the alloy is effectively improved, on the other hand, the solid solution or precipitated phase formed by the silicon and the scandium can play a role in strengthening the alloy, the mechanical performance of the titanium alloy is greatly improved, but if the addition amount of the silicon and the scandium is excessive, coarse precipitated phase can be formed, and the performance of the titanium alloy is reduced; 3. in the embodiment of the invention, the addition of a proper amount of lutetium element into the alloy can reduce or even eliminate grain boundary segregation of scandium element, can greatly improve the strength of the titanium alloy even if a small amount of scandium element is introduced, allows the addition of scandium element to be improved to a certain extent, and has a great strengthening effect on nano heterogeneous titanium alloy.
In some embodiments, the mass percentages of silicon, scandium, lutetium satisfy the relationship: 0.24% or less of [ Si ] + [ Sc ] + [ Lu ] < 1.2%.
In some embodiments, the high strength titanium alloy comprises: 0.01 to 0.2 percent of silicon, 0.3 to 0.4 percent of scandium and 0.2 to 0.3 percent of lutetium.
The embodiment of the invention also provides a preparation method of the high-strength titanium alloy, which comprises the steps of vacuum smelting, cogging forging, hot rolling thinning, asynchronous rolling, accumulative rolling and heat treatment.
The preparation method of the high-strength titanium alloy provided by the embodiment of the invention has the advantages and technical effects that 1, the method of the embodiment of the invention carries out plastic deformation with large deformation through asynchronous rolling and cumulative rolling so as to achieve the purposes of breaking precipitated phases and refining grains and form micron-level grains; 2. according to the method provided by the embodiment of the invention, the pure titanium grains can be effectively refined to submicron and nanometer dimensions by repeated rolling, and the precipitated phases are uniformly distributed among the pure titanium fine grains in submicron dimensions, so that the high-temperature mechanical property and fatigue and creep properties of the alloy are effectively improved, and meanwhile, the nanometer grains and micron-level grains growing after annealing produce synergistic effect, so that the low-temperature plasticity is improved while the high-temperature strength of the material is maintained; 3. according to the method provided by the embodiment of the invention, the asynchronous rolling and the accumulated rolling are combined, and repeated asynchronous rolling ensures that a layered coarse grain zone is formed in the final step of local recrystallization heat treatment, so that the interface between the coarse grain and the nanocrystalline is increased, and the synergistic strengthening effect of the coarse grain and the nanocrystalline in the nano heterogeneous structure is fully exerted; 4. the method of the embodiment of the invention can prepare the nano-scale precipitated phase, the titanium crystal grains and the micron-scale lamellar titanium crystal grains inlaid in the nano-scale precipitated phase and the titanium crystal grains, and can be realized only by adopting a conventional equipment tool, thereby having great industrial application prospect.
In some embodiments, the cogging forging comprises: heating the ingot obtained by vacuum smelting to 925-950 ℃, preserving heat for 1-3 hours, discharging from the furnace, forging for 1-2 times, and completing reversing three piers and three drawing, wherein the deformation of each time is more than 50%; and/or, before the cogging forging is carried out, the ingot casting obtained by vacuum smelting is kept at the temperature of 450-550 ℃ for 0.5-5 h.
In some embodiments, the hot rolling reduction includes forging an ingot obtained by cogging forging into a slab and hot rolling at 650 to 800 ℃ to obtain a sheet having a thickness of 1 to 2 mm.
In some embodiments, the ratio of the up-down rolling speed of the asynchronous rolling is 1.1-1.4, the thickness variation of each pass is not less than 0.1mm, the reversing rolling of the thin plate is reversed between each pass until the thickness is halved, and the thin plate is obtained, and preferably, the asynchronous rolling is completed at room temperature.
In some embodiments, the cumulative rolling includes cutting the asynchronously rolled sheet into two halves, heating the stacked sheets to 200-500 ℃ and maintaining the temperature for 5-10 minutes, and symmetrically rolling to halve the thickness to bond the sheets.
In some embodiments, the above-described asynchronous rolling and cumulative rolling processes are repeated such that the last rolling is to a thickness of 0.2-0.4 mm.
In some embodiments, the heat treatment includes annealing the resulting sheet at 400-500 ℃ for 4-6 minutes after cooling.
Drawings
FIG. 1 is a transmission electron microscope image of the titanium alloy produced in example 1.
Detailed Description
Reference will now be made in detail to embodiments of the present invention, examples of which are illustrated in the accompanying drawings. The embodiments described below by referring to the drawings are illustrative and intended to explain the present invention and should not be construed as limiting the invention.
The high-strength titanium alloy comprises 0.01-0.3% of silicon, 0.01-0.49% of scandium and 0.01-0.49% of lutetium, and the balance of titanium and unavoidable impurities in percentage by mass.
The high-strength titanium alloy provided by the embodiment of the invention can effectively improve the recrystallization temperature, high-temperature strength and structural stability of the titanium alloy by adding the trace scandium elements; the silicon element and the scandium element are added into the alloy simultaneously, so that a solid solution or a precipitated phase can be formed in the matrix, on one hand, the growth of titanium grains can be prevented, the proportion of nanocrystals in the product is increased to about 75%, the comprehensive performance of the alloy is effectively improved, on the other hand, the solid solution or the precipitated phase formed by the silicon and the scandium can play a role in strengthening the alloy, the mechanical performance of the titanium alloy is greatly improved, but if the adding amount of the silicon and the scandium is excessive, a coarse precipitated phase can be formed, and the performance of the titanium alloy is reduced; the addition of a proper amount of lutetium element in the alloy can reduce or even eliminate grain boundary segregation of scandium element, can greatly improve the strength of the titanium alloy even if a small amount of scandium element is introduced, allows the addition of scandium element to be improved to a certain extent, and has a great strengthening effect on nano heterogeneous titanium alloy.
In some embodiments, preferably, the mass percentages of silicon, scandium, lutetium satisfy the relationship: 0.24% or less of [ Si ] + [ Sc ] + [ Lu ] < 1.2%.
In the embodiment of the invention, the dosage of the silicon, scandium and lutetium elements meets the relational expression, which is favorable for exerting the synergistic effect among the elements and further improving the comprehensive performance of the titanium alloy.
In some embodiments, preferably, the high strength titanium alloy comprises: 0.01 to 0.2 percent of silicon, 0.3 to 0.4 percent of scandium and 0.2 to 0.3 percent of lutetium.
In the embodiment of the invention, the contents of scandium and lutetium are optimized, so that the performance of the titanium alloy can be further improved; if scandium is added in a small amount, the scandium is easy to burn, and the strengthening effect is very limited; the lutetium content is in a proper range, even if the scandium content is increased, the plasticity of the alloy is not obviously reduced, and the comprehensive performance of the titanium alloy is improved.
The embodiment of the invention also provides a preparation method of the high-strength titanium alloy, which comprises the steps of vacuum smelting, cogging forging, hot rolling thinning, asynchronous rolling, accumulative rolling and heat treatment.
According to the preparation method of the high-strength titanium alloy, the purpose of breaking precipitated phases and refining grains is achieved by carrying out plastic deformation with large deformation through asynchronous rolling and cumulative rolling, and micron-level grains are formed; the repeated rolling can effectively refine pure titanium grains to submicron and nanometer dimensions, and the precipitated phases are uniformly distributed among the pure titanium fine grains in submicron dimensions, so that the high-temperature mechanical property, fatigue and creep properties of the alloy are effectively improved, meanwhile, the nanometer grains and micron-level grains growing after annealing produce synergistic action, and the low-temperature plasticity is improved while the high-temperature strength of the material is maintained; the asynchronous rolling and the accumulated rolling are combined, and repeated asynchronous rolling ensures that a layered coarse grain zone is formed in the final step of local recrystallization heat treatment, the interface between coarse grains and nanocrystalline is increased, and the synergistic strengthening effect of the coarse grains and nanocrystalline in the nano heterogeneous structure is fully exerted; the nano-scale precipitated phase, titanium crystal grains and micron-scale lamellar titanium crystal grains inlaid in the titanium crystal grains can be prepared and realized by adopting a conventional equipment tool, and the method has great industrial application prospect.
In some embodiments, preferably, the cogging forging includes: heating the ingot obtained by vacuum smelting to 925-950 ℃, preserving heat for 1-3 hours, discharging from the furnace, forging for 1-2 times, wherein the deformation of each time is more than 50%, and finishing reversing three piers and three withdrawals; and/or, before the cogging forging is carried out, the ingot casting obtained by vacuum smelting is kept at the temperature of 450-550 ℃ for 0.5-5 h.
According to the method provided by the embodiment of the invention, the unidirectional deformation of more than 50% of each firing is adopted in cogging forging, so that the grain deformation can be effectively promoted, the nano-level dynamic recrystallization is realized, and if the unidirectional deformation of each firing is less than 50%, the nano-level grain is difficult to obtain due to insufficient deformation.
In some embodiments, the hot rolling reduction preferably includes forging an ingot obtained by cogging forging into a slab and hot rolling at 650 to 800 ℃ to obtain a sheet having a thickness of 1 to 2 mm.
In some embodiments, the ratio of the up-down rolling speed of the asynchronous rolling is preferably 1.1-1.4, the thickness variation of each pass is not less than 0.1mm, the reversing rolling of the thin plate is reversed between each pass until the thickness is halved, and the thin plate is obtained, and the asynchronous rolling is preferably completed at room temperature.
In the embodiment of the invention, the thickness variation of each pass is not less than 0.1mm, so that the deformation of the crystal grains can be effectively promoted, the nano-level dynamic recrystallization is realized, and the nano-level crystal grains are difficult to obtain if the thickness variation of each pass is less than 0.1mm and the deformation is insufficient; it is further preferred that rolling at room temperature is effective to prevent the growth of recrystallized grains so that more grains remain on the nanoscale, more effective to strengthen the material.
In some embodiments, preferably, the cumulative rolling includes cutting the asynchronously rolled sheet into two halves, heating the stacked sheets to 200-500 ℃ for 5-10 minutes, and symmetrically rolling to a thickness halved for bonding.
In some embodiments, the above-described asynchronous rolling and cumulative rolling processes are preferably repeated such that the last rolling is to a thickness of 0.2 to 0.4mm.
In some embodiments, the heat treatment preferably includes annealing the resulting sheet at 400-500 ℃ for 4-6 minutes after cooling.
In the embodiment of the invention, the annealing treatment is carried out on the plate, so that the internal stress can be eliminated while promoting part of nano grains to grow to a micrometer scale; the temperature and time of the heat treatment can be adjusted according to the specification of the sample, the sample with smaller weight and volume can be subjected to short-time heat treatment at low temperature, and the sample with larger weight and volume can be subjected to long-time heat treatment at higher temperature, so that the heat treatment can thoroughly eliminate the internal stress of the sample.
The present invention will be described in detail with reference to specific embodiments and drawings.
Example 1
(1) Vacuum smelting by a vacuum consumable arc furnace, and then preserving the temperature of the obtained cast ingot at 500 ℃ for 5 hours;
(2) Cogging forging: heating the ingot to 925 ℃, preserving heat for 3 hours, discharging and forging, and completing reversing three piers and three drawing with 2 times, wherein the unidirectional deformation amount of each time is 51%;
(3) And (3) hot rolling and thinning: forging an ingot obtained by cogging forging into a plate blank, and hot-rolling to obtain a thin plate with the thickness of 2 mm;
(4) Asynchronous rolling: asynchronous rolling with the up-down rolling speed ratio of 1.3 is completed on the obtained sheet at room temperature, the thickness variation of each pass is 0.1 millimeter, and the sheet is rolled in a reversing way between each pass until the thickness is halved, so that a sheet is obtained;
(5) And (3) accumulating and rolling: cutting the sheet into two halves, heating the stacked sheet to 500 ℃ for 10 minutes, symmetrically rolling to reduce the thickness by half, repeating the asynchronous rolling process, continuously repeating the sheet stacking, annealing, bonding rolling and asynchronous rolling for a plurality of times, and finally rolling to a thickness of 0.3 mm;
(6) The obtained plate was cooled and annealed at 475 ℃ for 5 minutes to obtain a titanium alloy.
The titanium alloy prepared in the embodiment 1 is subjected to scanning electron microscope characterization, and the result is shown in fig. 1, from which it can be seen that the prepared titanium alloy has a nano heterogeneous structure, and can effectively improve the high-temperature strength, low-temperature plasticity and fatigue and creep properties of the titanium alloy.
The alloy composition obtained in example 1 is shown in Table 1 and the properties are shown in Table 2.
Example 2
(1) Vacuum smelting by a vacuum consumable arc furnace, and then preserving the obtained cast ingot at 500 ℃ for 0.5 hour
(2) Cogging forging: heating the ingot to 950 ℃, preserving heat for 1 hour, discharging and forging, and completing reversing three piers and three drawing with 1 firing, wherein the unidirectional deformation amount of each firing is 65%;
(3) And (3) hot rolling and thinning: forging an ingot obtained by cogging forging into a plate blank, and hot-rolling to obtain a thin plate with the thickness of 2 mm;
(4) Asynchronous rolling: asynchronous rolling with the up-down rolling speed ratio of 1.1 is completed on the obtained sheet at room temperature, the thickness variation of each pass is 0.3 millimeter, and the sheet is rolled in a reversing way between each pass until the thickness is halved, so that a sheet is obtained;
(5) And (3) accumulating and rolling: cutting the sheet into two halves, heating the stacked sheet to 450 ℃ for preserving heat for 11 minutes, symmetrically rolling to reduce the thickness by half, then repeating the asynchronous rolling process, continuously repeating the slicing stacking, annealing, bonding rolling and asynchronous rolling for a plurality of times, and finally rolling to the thickness of 0.2 mm;
(6) The obtained sheet was cooled and then annealed at 400℃for 6 minutes to obtain a titanium alloy.
The alloy composition obtained in example 2 is shown in Table 1 and the properties are shown in Table 2.
Example 3
(1) Vacuum smelting by a vacuum consumable arc furnace, and then preserving the temperature of the obtained cast ingot at 500 ℃ for 3 hours;
(2) Cogging forging: heating the ingot to 935 ℃, preserving heat for 2 hours, discharging and forging, and completing reversing three piers and three drawing with 1 firing, wherein the unidirectional deformation amount of each firing is 60%;
(3) And (3) hot rolling and thinning: forging an ingot obtained by cogging forging into a plate blank, and hot-rolling to obtain a thin plate with the thickness of 2 mm;
(4) Asynchronous rolling: asynchronous rolling with the up-down rolling speed ratio of 1.4 is completed on the obtained sheet at room temperature, the thickness variation of each pass is 0.2 mm, and the sheet is rolled in a reversing way between each pass until the thickness is halved, so that a sheet is obtained;
(5) And (3) accumulating and rolling: cutting the sheet into two halves, heating the stacked sheet to 350 ℃, preserving heat for 8 minutes, symmetrically rolling to reduce the thickness by half, repeating the asynchronous rolling process, continuously repeating the slicing stacking, annealing, bonding rolling and asynchronous rolling for a plurality of times, and finally rolling to a thickness of 0.4 mm;
(6) The obtained plate was cooled and annealed at 500℃for 4 hours to obtain a titanium alloy.
The alloy composition obtained in example 3 is shown in Table 1 and the properties are shown in Table 2.
Examples 4 to 6
The same procedure as in example 1 was followed except that the alloy composition was varied, specifically as shown in Table 1 and the properties were as shown in Table 2.
Comparative example 1
The same preparation method as in example 1 is different only in the alloying elements: the titanium alloy prepared in comparative example 1 has the composition shown in Table 1 and the properties shown in Table 2, wherein Si represents 0.75wt.%, sc represents 0.6wt.%, and Lu represents 0.5 wt.%.
Comparative example 2
The same procedure as in example 1 is followed, except that the alloying elements differ: the titanium alloy composition obtained in comparative example 2 was shown in Table 1, and the properties were shown in Table 2, without adding Si, sc and Lu elements.
Comparative example 3
The same procedure as in example 1 was repeated except that Lu was not added, and the composition and properties of the titanium alloy obtained in comparative example 3 were shown in Table 1 and Table 2.
Comparative example 4
The same procedure as in example 1 is followed, except that: in the step (2), the unidirectional deformation per firing time during the cogging forging was 45%, and the properties of the titanium alloy obtained in comparative example 4 are shown in Table 2.
Comparative example 5
The same procedure as in example 1 is followed, except that: in the step (4), the thickness variation per pass during the asynchronous rolling was 0.4mm, and the properties of the titanium alloy obtained in the comparative example 5 are shown in Table 2.
Comparative example 6
The same procedure as in example 1 is followed, except that: in the step (4), the asynchronous rolling is changed to synchronous rolling, and the properties of the titanium alloy prepared in the comparative example 6 are shown in Table 2.
TABLE 1
| Si(％) | Sc(％) | Lu(％) | Titanium and impurities | [Si]+[Sc]+[Lu] | |
| Example 1 | 0.11 | 0.3 | 0.2 | Remainder of the process | 0.61 |
| Example 2 | 0.22 | 0.35 | 0.35 | Remainder of the process | 0.92 |
| Example 3 | 0.2 | 0.3 | 0.2 | Remainder of the process | 0.7 |
| Example 4 | 0.1 | 0.1 | 0.04 | Remainder of the process | 0.24 |
| Example 5 | 0.22 | 0.25 | 0.18 | Remainder of the process | 0.65 |
| Example 6 | 0.3 | 0.45 | 0.42 | Remainder of the process | 1.17 |
| Comparative example 1 | 0.75 | 0.6 | 0.5 | Remainder of the process | 1.85 |
| Comparative example 2 | 0 | 0 | 0 | Remainder of the process | 0 |
| Comparative example 3 | 0.11 | 0.12 | 0 | Remainder of the process | 0.23 |
| Comparative example 4 | 0.11 | 0.3 | 0.2 | Remainder of the process | 0.61 |
| Comparative example 5 | 0.11 | 0.3 | 0.2 | Remainder of the process | 0.61 |
| Comparative example 6 | 0.11 | 0.3 | 0.2 | Remainder of the process | 0.61 |
TABLE 2
Note that: the fatigue limit test conditions were: the test frequency is 30-50 Hz, and the stress ratio is-1;
creep rate refers to the amount of deformation per hour at 400 ℃ and a stress value of 60% yield strength, as expressed by 0.0392/h, meaning a deformation per hour of 3.92%; the larger the number, the worse the creep resistance of the material.
As can be seen from the data in the above table, in examples 1 to 6, a proper amount of silicon, scandium and lutetium are added, and when the content thereof satisfies the relation 0.24 < Si < + > Sc < + > Lu < + > 1.2, the alloy has excellent tensile strength and certain plasticity, and the tensile strength of the alloy at room temperature can reach over 980 MPa; and the recrystallization temperature of the alloy is increased to more than 440 ℃, the fatigue limit reaches more than 340MPa, and the alloy has better creep resistance.
In comparative example 1, excessive amounts of silicon, scandium, and lutetium were added to form coarse precipitated phases in the alloy, and compared with the alloy produced in example 1, the tensile strength of the alloy was reduced to only 710MPa at room temperature, and the alloy had no plasticity and a fatigue limit reduced to 270MPa.
In comparative example 2, no silicon, scandium and lutetium elements were added, and it was found that the alloy was inferior in combination properties to the alloy prepared in example 1, and although toughness was improved to some extent, tensile strength was lowered, the use requirement could not be satisfied, and creep rate was increased to 0.0464/h, and creep resistance was inferior.
In comparative example 3, only silicon and scandium elements were added, and the plasticity and creep rate were equivalent to those of the alloy prepared in example 1, but the tensile strength was remarkably reduced to 840MPa at room temperature, and the fatigue limit was also reduced to 300MPa. The reason is that after lutetium element is not added, grain boundary segregation of scandium element exists in the alloy, which is unfavorable for improving the strength of the alloy.
Comparative examples 4 to 6 are the same as the alloy elements used in example 1, except that the parameters related to the preparation were adjusted, and the alloy properties were also degraded to some extent.
In the present disclosure, the terms "one embodiment," "some embodiments," "examples," "specific examples," or "some examples," etc., mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the present disclosure. In this specification, schematic representations of the above terms are not necessarily directed to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples. Furthermore, the different embodiments or examples described in this specification and the features of the different embodiments or examples may be combined and combined by those skilled in the art without contradiction.
While the above embodiments have been shown and described, it should be understood that the above embodiments are illustrative and not to be construed as limiting the invention, and that variations, modifications, alternatives, and variations of the above embodiments may be made by those of ordinary skill in the art without departing from the scope of the invention.
Claims (10)
1. A high strength titanium alloy comprising: 0.01 to 0.3 percent of silicon, 0.01 to 0.49 percent of scandium and 0.01 to 0.49 percent of lutetium, and the balance of titanium and unavoidable impurities in percentage by mass.
2. The high strength titanium alloy of claim 1, wherein the mass percentages of silicon, scandium, lutetium satisfy the relationship: 0.24% or less of [ Si ] + [ Sc ] + [ Lu ] < 1.2%.
3. The high strength titanium alloy according to claim 1, comprising: 0.01 to 0.2 percent of silicon, 0.3 to 0.4 percent of scandium and 0.2 to 0.3 percent of lutetium.
4. A method for producing a high-strength titanium alloy according to any one of claims 1 to 3, comprising sequentially performing vacuum melting, cogging forging, hot rolling reduction, asynchronous rolling, cumulative rolling and heat treatment.
5. The method for producing a high-strength titanium alloy according to claim 4, wherein the cogging forging includes: heating the ingot obtained by vacuum smelting to 925-950 ℃, preserving heat for 1-3 hours, discharging from the furnace, forging for 1-2 times, and completing reversing three piers and three drawing, wherein the deformation of each time is more than 50%; and/or, before the cogging forging is carried out, the ingot casting obtained by vacuum smelting is kept at the temperature of 450-550 ℃ for 0.5-5 h.
6. The method for producing a high-strength titanium alloy according to claim 4, wherein the hot rolling and ironing comprises forging an ingot obtained by cogging forging into a slab and hot rolling at 650 to 800 ℃ to obtain a sheet having a thickness of 1 to 2 mm.
7. The method for producing a high-strength titanium alloy according to claim 4, wherein the asynchronous rolling is performed at a speed ratio of 1.1 to 1.4 in each pass, the thickness variation is not less than 0.1mm, and the sheet is reversed between each pass until the thickness is halved, whereby a sheet is obtained, and preferably the asynchronous rolling is performed at room temperature.
8. The method for producing a high-strength titanium alloy according to claim 4, wherein the cumulative rolling includes cutting the sheet obtained by asynchronous rolling into two halves, heating the stacked sheet to 200 to 500 ℃ and holding for 5 to 10 minutes, and symmetrically rolling to a thickness halved to bond the sheets.
9. The method for producing a high-strength titanium alloy according to any one of claims 4 to 8, wherein the above-mentioned asynchronous rolling and cumulative rolling are repeated so that the thickness of the final rolling is 0.2 to 0.4mm.
10. The method for producing a high-strength titanium alloy according to claim 9, wherein the heat treatment comprises cooling the obtained sheet and annealing at 400 to 500 ℃ for 4 to 6 minutes.
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