CN115786767B - High-toughness titanium alloy oil pipe and heat treatment method thereof - Google Patents
High-toughness titanium alloy oil pipe and heat treatment method thereof Download PDFInfo
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- 229910001069 Ti alloy Inorganic materials 0.000 title claims abstract description 160
- 238000010438 heat treatment Methods 0.000 title claims abstract description 74
- 238000000034 method Methods 0.000 title claims abstract description 51
- 230000032683 aging Effects 0.000 claims abstract description 29
- 238000010791 quenching Methods 0.000 claims abstract description 17
- 230000000171 quenching effect Effects 0.000 claims abstract description 17
- 239000010936 titanium Substances 0.000 claims abstract description 14
- 239000012535 impurity Substances 0.000 claims abstract description 8
- 229910052729 chemical element Inorganic materials 0.000 claims abstract description 4
- 238000001816 cooling Methods 0.000 claims description 59
- 230000008569 process Effects 0.000 claims description 35
- 238000005496 tempering Methods 0.000 claims description 20
- 239000011159 matrix material Substances 0.000 claims description 15
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 11
- 238000005097 cold rolling Methods 0.000 claims description 4
- 230000007704 transition Effects 0.000 claims description 4
- 239000006104 solid solution Substances 0.000 abstract description 8
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 abstract description 6
- 238000002156 mixing Methods 0.000 abstract description 4
- 239000003345 natural gas Substances 0.000 abstract description 3
- 239000003209 petroleum derivative Substances 0.000 abstract description 2
- 239000000243 solution Substances 0.000 description 24
- 229910045601 alloy Inorganic materials 0.000 description 18
- 239000000956 alloy Substances 0.000 description 18
- 238000004321 preservation Methods 0.000 description 14
- KDLHZDBZIXYQEI-UHFFFAOYSA-N Palladium Chemical compound [Pd] KDLHZDBZIXYQEI-UHFFFAOYSA-N 0.000 description 11
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 description 10
- 239000011651 chromium Substances 0.000 description 10
- 229910052719 titanium Inorganic materials 0.000 description 10
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 9
- 230000009286 beneficial effect Effects 0.000 description 7
- 238000005260 corrosion Methods 0.000 description 6
- 230000007797 corrosion Effects 0.000 description 6
- 230000002431 foraging effect Effects 0.000 description 6
- 239000007789 gas Substances 0.000 description 6
- 239000000463 material Substances 0.000 description 5
- 238000005728 strengthening Methods 0.000 description 5
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 description 4
- 229910000831 Steel Inorganic materials 0.000 description 4
- 229910052799 carbon Inorganic materials 0.000 description 4
- 230000000694 effects Effects 0.000 description 4
- 229910052757 nitrogen Inorganic materials 0.000 description 4
- 238000005096 rolling process Methods 0.000 description 4
- 239000010959 steel Substances 0.000 description 4
- 229910001040 Beta-titanium Inorganic materials 0.000 description 3
- 238000010923 batch production Methods 0.000 description 3
- 230000001419 dependent effect Effects 0.000 description 3
- 229910052739 hydrogen Inorganic materials 0.000 description 3
- 238000004519 manufacturing process Methods 0.000 description 3
- 229910052760 oxygen Inorganic materials 0.000 description 3
- 238000002161 passivation Methods 0.000 description 3
- 238000012545 processing Methods 0.000 description 3
- 230000009466 transformation Effects 0.000 description 3
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 2
- 238000003723 Smelting Methods 0.000 description 2
- NINIDFKCEFEMDL-UHFFFAOYSA-N Sulfur Chemical compound [S] NINIDFKCEFEMDL-UHFFFAOYSA-N 0.000 description 2
- 238000000137 annealing Methods 0.000 description 2
- 238000009826 distribution Methods 0.000 description 2
- 238000005242 forging Methods 0.000 description 2
- 229910052750 molybdenum Inorganic materials 0.000 description 2
- 229910052759 nickel Inorganic materials 0.000 description 2
- 230000008520 organization Effects 0.000 description 2
- 238000005554 pickling Methods 0.000 description 2
- 238000005498 polishing Methods 0.000 description 2
- -1 smelting Chemical compound 0.000 description 2
- 230000000087 stabilizing effect Effects 0.000 description 2
- 229910052717 sulfur Inorganic materials 0.000 description 2
- 239000011593 sulfur Substances 0.000 description 2
- 238000012360 testing method Methods 0.000 description 2
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 1
- VYZAMTAEIAYCRO-UHFFFAOYSA-N Chromium Chemical compound [Cr] VYZAMTAEIAYCRO-UHFFFAOYSA-N 0.000 description 1
- ZOKXTWBITQBERF-UHFFFAOYSA-N Molybdenum Chemical compound [Mo] ZOKXTWBITQBERF-UHFFFAOYSA-N 0.000 description 1
- 239000008186 active pharmaceutical agent Substances 0.000 description 1
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 1
- 229910052782 aluminium Inorganic materials 0.000 description 1
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 1
- 230000000903 blocking effect Effects 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 229910052804 chromium Inorganic materials 0.000 description 1
- 238000013461 design Methods 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 230000018109 developmental process Effects 0.000 description 1
- 239000001257 hydrogen Substances 0.000 description 1
- 125000004435 hydrogen atom Chemical class [H]* 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 230000002401 inhibitory effect Effects 0.000 description 1
- 229910052742 iron Inorganic materials 0.000 description 1
- 229910000734 martensite Inorganic materials 0.000 description 1
- 239000011733 molybdenum Substances 0.000 description 1
- 230000007935 neutral effect Effects 0.000 description 1
- 239000001301 oxygen Substances 0.000 description 1
- 229910052763 palladium Inorganic materials 0.000 description 1
- 239000003208 petroleum Substances 0.000 description 1
- 238000010587 phase diagram Methods 0.000 description 1
- 239000003761 preservation solution Substances 0.000 description 1
- VSZWPYCFIRKVQL-UHFFFAOYSA-N selanylidenegallium;selenium Chemical compound [Se].[Se]=[Ga].[Se]=[Ga] VSZWPYCFIRKVQL-UHFFFAOYSA-N 0.000 description 1
- 230000035945 sensitivity Effects 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
- 229910052720 vanadium Inorganic materials 0.000 description 1
- LEONUFNNVUYDNQ-UHFFFAOYSA-N vanadium atom Chemical compound [V] LEONUFNNVUYDNQ-UHFFFAOYSA-N 0.000 description 1
Classifications
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P10/00—Technologies related to metal processing
- Y02P10/20—Recycling
Abstract
The invention relates to the technical field of petroleum and natural gas pipes, in particular to a high-toughness titanium alloy oil pipe and a heat treatment method thereof. The high-toughness titanium alloy oil pipe comprises the following chemical elements in percentage by weight: al:3.5% -4.0%, mo:2.5% -3.5%, cr:3.0% -3.5%, zr:0.5 to 0.6 percent, pd is less than or equal to 0.1 percent, V is less than or equal to 0.1 percent, C is less than or equal to 0.015 percent, H is less than or equal to 0.01 percent, O is less than or equal to 0.01 percent, N is less than or equal to 0.05 percent, fe is less than or equal to 0.05 percent, and the balance is Ti and unavoidable impurities. According to the invention, by carrying out solid solution and aging two-step heat treatment on the titanium alloy oil pipe in the step-type continuous quenching furnace and the step-type continuous quenching furnace respectively, a binary structure formed by mixing a primary phase and a secondary phase can be obtained, so that the titanium alloy oil pipe has higher strength and toughness.
Description
Technical Field
The invention relates to the technical field of petroleum and natural gas pipes, in particular to a high-toughness titanium alloy oil pipe and a heat treatment method thereof.
Background
The sulfur-containing oil and gas fields in the widely distributed natural gas resources in China account for a considerable proportion, and several domestic oil and gas fields such as Sichuan, tarim oil and the like all have high sulfur-containing oil and gas blocks. The titanium alloy has high strength, low density, excellent corrosion resistance and high fatigue resistance, and even if the service temperature is up to 260 ℃, the strength is still higher, which is beneficial to the application of the titanium alloy in deep wells, ultra-deep wells and oil gas wells with severe corrosion conditions. Therefore, the titanium alloy oil gas pipe becomes one of the selectable pipes for deep oil gas development in China.
The titanium alloy pipe is used as a novel corrosion-resistant oil pipe, and the toughness index of the pipe generally adopts the specification of standard P110 steel grade oil pipes such as general petroleum casing pipe API 5CT or GB/T19830 on toughness: the longitudinal direction was 41J at 0 ℃. Or the impact power requirement of the P110 steel grade titanium alloy oil pipe is met by adopting the titanium alloy oil pipe standard SY/T6896.3-2016: the longitudinal direction was 41J at-10 ℃. However, although the impact toughness index of the titanium alloy oil pipe in the current market meets the standard requirement, the actual impact power value is often lower than the threshold value required by the standard, and the impact toughness ratio of the titanium alloy oil pipe to the common steel or nickel-based alloy oil pipe in the market is obviously lower. Because the material properties of the titanium alloy pipe are greatly different from those of steel, nickel-based alloy and other oil pipes, the performance indexes of the product standards in the market still have failure problems or risks in the actual application process, and the good strength matching in the service environment cannot be met.
Disclosure of Invention
Aiming at the problems, the invention aims to provide the high-toughness titanium alloy oil pipe and the heat treatment method thereof, wherein the two-step heat treatment of solid solution and aging is carried out on the titanium alloy oil pipe, so that a binary structure formed by mixing a primary phase and a secondary phase can be obtained, the titanium alloy oil pipe has higher strength and toughness meeting the use conditions, the method is convenient to operate, the conventional operation equipment and flow are not changed, and the method is suitable for batch production in factories and has higher production efficiency.
The technical scheme of the invention is as follows: the high-toughness titanium alloy oil pipe comprises the following chemical element components in percentage by weight: al:3.5% -4.0%, mo:2.5% -3.5%, cr:3.0% -3.5%, zr:0.5 to 0.6 percent, pd is less than or equal to 0.1 percent, V is less than or equal to 0.1 percent, C is less than or equal to 0.015 percent, H is less than or equal to 0.01 percent, O is less than or equal to 0.01 percent, N is less than or equal to 0.05 percent, fe is less than or equal to 0.05 percent, and the balance is Ti and unavoidable impurities.
The selection basis of the chemical components of the high-toughness titanium alloy oil pipe is as follows:
design ranges of aluminum (Al), molybdenum (Mo), chromium (Cr), zirconium (Zr), palladium (Pd) and vanadium (V): 3.5-4.0% of Al, 2.5-3.5% of Mo, 3.0-3.5% of Cr, 0.5-0.6% of Zr, less than or equal to 0.1% of Pd and less than or equal to 0.1% of V. The reason for this is: the Al element mainly has a solid solution strengthening effect, stabilizes an alpha phase, improves the specific strength of the alloy and improves the heat resistance; if the content of Al element is too high, ti is easily formed 3 The Al brittle phase reduces the mechanical properties of the material. Mo and V are beta stable elements, mainly play a role in solid solution strengthening beta phase, reduce phase transition points and increase hardenability, and the Mo element can also improve the corrosion resistance of the titanium alloy. The Cr element mainly plays a role in strengthening, stabilizes beta phase, and has the effect of inhibiting eutectoid when being added together with Mo. Zr is neutral element, mainly plays a role inThe heat resistance is further improved by the solid solution strengthening effect. Pd element improves the corrosion resistance of the titanium alloy and enlarges the passivation range of the titanium alloy. The alloy element control range designed by the invention is beneficial to improving the performances of the titanium alloy, such as strength, toughness, corrosion and the like; on the other hand, the hot processing performance of the material is improved.
The content of impurity elements of carbon (C), oxygen (O), nitrogen (N), hydrogen (H) and iron (Fe) is strictly controlled in a range: c is less than or equal to 0.015%, H is less than or equal to 0.01%, O is less than or equal to 0.01%, N is less than or equal to 0.05%, and Fe is less than or equal to 0.05%. The reason for this is: o, N, C is a common impurity element in titanium alloy, and can improve the strength of titanium and reduce the plasticity of titanium; however, a certain amount of O element contributes to the improvement of the tensile strength of the alloy, and thus the O content cannot be too low. When the content of H element reaches a certain amount in the titanium alloy, the sensitivity of the titanium alloy to the notch is greatly improved, so that the performance such as impact toughness of a notch sample is sharply reduced. The Fe element is an important alloy element of metastable beta titanium alloy, and can obviously reduce the martensitic transformation temperature of the titanium alloy. The impurity element control range designed by the invention is beneficial to reducing the influence of C, H, O, N, fe and other impurity elements on the titanium alloy performance by the heat treatment process; on the other hand, the method is beneficial to reducing the heat treatment temperature parameter.
The titanium alloy oil pipe is a cold-rolled titanium alloy oil pipe, the rolling state structure of the cold-rolled titanium alloy oil pipe blank is that equiaxial alpha phases and net alpha phases are distributed on a beta phase matrix, and the alpha phase content is less than or equal to 30%.
In the rolled structure of the cold-rolled titanium alloy oil pipe blank, titanium with a close-packed hexagonal structure is called an alpha phase, and titanium with a body-centered cubic structure is called a beta phase, and the two phases are called an alpha+beta double phase. The processing technology of the cold-rolled titanium alloy oil pipe blank adopts a mature titanium alloy manufacturing technology, and the basic flow of the technology comprises sponge titanium, smelting, titanium ingot, forging, hot perforation, rolling, pickling, annealing, continuous cold rolling, surface polishing and heat treatment of a blank. Since the increase of the alpha proportion in the alpha+beta titanium alloy generally increases the plasticity and toughness of the alloy to reduce the strength of the alloy, the control of the alpha phase content not to exceed 30 percent is beneficial to realizing the high strength and high plastic toughness of the titanium alloy through subsequent heat treatment.
A heat treatment method of a high-toughness titanium alloy oil pipe comprises the following steps:
s1: carrying out solution treatment on the titanium alloy oil pipe blank; the specific process is as follows:
heating the rolled titanium alloy oil pipe blank to beta phase transition temperature T in a step-type continuous quenching furnace β Preserving the temperature at 30-110 ℃ for 1-2 hours, and then cooling to room temperature by adopting a water cooling mode;
s2: aging the titanium alloy oil pipe blank; the specific process is as follows:
heating the titanium alloy oil pipe blank cooled after solution treatment in the step S1 to 560-600 ℃ in a step-by-step continuous tempering furnace, and preserving heat for 2-8 hours;
s3: carrying out heat car straightening treatment on the titanium alloy oil pipe blank; the specific process is as follows:
and (3) conveying the titanium alloy oil pipe blank subjected to ageing treatment in the step-by-step continuous tempering furnace in the step (S2) into a straightener through a roller way to carry out hot lift straightening, straightening at a temperature of more than 450 ℃, and then cooling to room temperature in an air cooling mode on a cooling bed.
The titanium alloy oil pipe blank in the S1 is a cold-rolled titanium alloy pipe, the rolled structure of the titanium alloy oil pipe blank in the S1 is that equiaxial alpha phases and net alpha phases are distributed on a beta phase matrix, and the alpha phase content is less than or equal to 30%.
And in the step S1, the titanium alloy oil pipe blank is subjected to solution treatment, and the rolled titanium alloy oil pipe blank is heated to a heating temperature of 830-910 ℃ in a step-type continuous quenching furnace.
And (2) the heating speed of the step-type continuous quenching furnace in the step S1 is 20-25 ℃/min.
And (2) heating the furnace at a heating speed of 20-25 ℃/min in the heating process of the step-type continuous tempering furnace.
The organization form of the titanium alloy oil pipe tube blank after the aging treatment process in the step S2 is that discontinuous spherical alpha phase, rod-shaped alpha phase and needle-shaped alpha phase are distributed on a beta phase matrix, and the alpha phase content is less than or equal to 30 percent.
The content of the spherical alpha phase is more than 10 percent.
And (2) after the aging treatment process in the step (S2), the yield strength of the titanium alloy oil pipe blank is 855-840 MPa, the tensile strength is 930-950 MPa, and the full-size impact energy at the temperature of minus 10 ℃ is 56-73J.
The invention has the beneficial effects that: 1. according to the invention, through solution treatment of the titanium alloy oil pipe blank, when the temperature of the material is raised to an alpha+beta two-phase region, the alpha phase with higher content and larger size is remained due to the existence of elements (such as Al) for stabilizing the alpha phase, and the rest is converted into the beta phase, so that the remained alpha phase is named as a primary alpha phase. Since the beta phase is a high temperature phase, the alpha phase such as strip, needle and the like is separated out in the subsequent cooling process because of instability, and the alpha phase is a secondary alpha phase. When the titanium alloy oil pipe blank is subjected to solution treatment, the size, the shape and the distribution of a primary alpha phase are controlled through the alpha+beta double-phase region, the rapid growth of beta-phase grains is avoided, a double-state structure formed by mixing the primary phase and the secondary phase can be obtained, and the titanium alloy oil pipe has higher strength and toughness meeting the use conditions; 2. the aging treatment temperature is in a relatively high temperature range of 560-600 ℃, in this range, the secondary alpha phase is tiny and needle-shaped during aging treatment, the flaky alpha phase is not generated, dislocation movement can be prevented, the strength of the alloy is improved, a small amount of alpha phase is attached to the spherical alpha phase in a dependent manner, the content of the spherical alpha phase is increased, the size of the spherical alpha phase is increased, and therefore the plasticity and the toughness of the titanium alloy are improved to a certain extent; 3. compared with the traditional solid solution aging process, the invention can effectively regulate and control the contents and the sizes of spherical alpha phase, rod-shaped alpha phase and needle-shaped alpha phase in the microstructure of the titanium alloy oil pipe by reasonably selecting the process parameters on the basis of comprehensively considering the parameters such as heat treatment temperature, heating mode, heat preservation time, cooling mode and the like, thereby realizing good matching among strength, plasticity and toughness; the process flow is suitable for factory batch production equipment, and the process is simple and stable and convenient to operate.
Drawings
FIG. 1 is a microstructure of a titanium alloy oil pipe in example 2 of the present invention.
FIG. 2 is a microstructure of a titanium alloy oil pipe in example 3 of the present invention.
FIG. 3 is a microstructure of a titanium alloy oil pipe in example 4 of the present invention.
FIG. 4 is a microstructure of a titanium alloy oil pipe in example 5 of the present invention.
FIG. 5 is a microstructure of a titanium alloy oil tube in example 6 of the present invention.
FIG. 6 is a microstructure of a titanium alloy oil tube in example 7 of the present invention.
Detailed Description
The invention is described in further detail below with reference to examples:
example 1
The high-toughness titanium alloy oil pipe comprises the following chemical element components in percentage by weight: al:3.5% -4.0%, mo:2.5% -3.5%, cr:3.0% -3.5%, zr:0.5 to 0.6 percent, pd is less than or equal to 0.1 percent, V is less than or equal to 0.1 percent, C is less than or equal to 0.015 percent, H is less than or equal to 0.01 percent, O is less than or equal to 0.01 percent, N is less than or equal to 0.05 percent, fe is less than or equal to 0.05 percent, and the balance is Ti and unavoidable impurities.
The titanium alloy oil pipe is a cold-rolled titanium alloy oil pipe, the rolling state structure of the cold-rolled titanium alloy oil pipe blank is that equiaxial alpha phases and net alpha phases are distributed on a beta phase matrix, and the alpha phase content is less than or equal to 30%.
In the rolled structure of the cold-rolled titanium alloy oil pipe blank, titanium with a close-packed hexagonal structure is called an alpha phase, and titanium with a body-centered cubic structure is called a beta phase, and the two phases are called an alpha+beta double phase. The processing technology of the cold-rolled titanium alloy oil pipe blank adopts a mature titanium alloy manufacturing technology, and the basic flow of the technology comprises sponge titanium, smelting, titanium ingot, forging, hot perforation, rolling, pickling, annealing, continuous cold rolling, surface polishing and heat treatment of a blank. Since the increase of the alpha proportion in the alpha+beta titanium alloy generally increases the plasticity and toughness of the alloy to reduce the strength of the alloy, the control of the alpha phase content not to exceed 30 percent is beneficial to realizing the high strength and high plastic toughness of the titanium alloy through subsequent heat treatment.
A heat treatment method of a high-toughness titanium alloy oil pipe comprises the following steps:
s1: carrying out solution treatment on the titanium alloy oil pipe blank; the specific process is as follows:
heating the rolled titanium alloy oil pipe blank to beta phase transition temperature T in a step-type continuous quenching furnace β Preserving the temperature at 30-110 ℃ for 1-2 hours, and then cooling to room temperature by adopting a water cooling mode;
s2: aging the titanium alloy oil pipe blank; the specific process is as follows:
heating the titanium alloy oil pipe blank cooled after solution treatment in the step S1 to 560-600 ℃ in a step-by-step continuous tempering furnace, and preserving heat for 2-8 hours;
s3: carrying out heat car straightening treatment on the titanium alloy oil pipe blank; the specific process is as follows:
and (3) conveying the titanium alloy oil pipe subjected to ageing treatment in the step S2 to a straightener through a roller way to carry out hot lift straightening, straightening at a temperature of more than 450 ℃, and then cooling to room temperature in an air cooling mode on a cooling bed.
The titanium alloy oil pipe blank in the S1 is a cold-rolled titanium alloy pipe, the rolled structure of the titanium alloy oil pipe blank in the S1 is that equiaxial alpha phases and net alpha phases are distributed on a beta phase matrix, and the alpha phase content is less than or equal to 30%.
And in the step S1, the titanium alloy oil pipe blank is subjected to solution treatment, and the rolled titanium alloy oil pipe blank is heated to a heating temperature of 830-910 ℃ in a step-type continuous quenching furnace.
And (2) the heating speed of the step-type continuous quenching furnace in the step S1 is 20-25 ℃/min.
And (2) heating the furnace at a heating speed of 20-25 ℃/min in the heating process of the step-type continuous tempering furnace.
The organization form of the titanium alloy oil pipe tube blank after the aging treatment process in the step S2 is that discontinuous spherical alpha phase, rod-shaped alpha phase and needle-shaped alpha phase are distributed on a beta phase matrix, the content of the alpha phase is less than or equal to 30%, and the content of the spherical alpha phase is more than 10%.
And (2) after the aging treatment process in the step (S2), the yield strength of the titanium alloy oil pipe blank is 855-840 MPa, the tensile strength is 930-950 MPa, and the full-size impact energy at the temperature of minus 10 ℃ is 56-73J.
The heat treatment method has the solution treatment temperature in the alpha+beta phase diagram double-phase region of the titanium alloy, wherein the alpha phase is a low-temperature phase, the beta phase is a high-temperature phase, and the transformation temperature T of the beta phase is the transformation temperature T of the beta phase β The excessive phase alpha phase is converted into beta phase during the heat preservation solution treatment at the temperature of 30-110 ℃, meanwhile, the solubility of the alloy elements with the strengthening effect is different at high temperature and low temperature, and the alloy elements cannot be separated out during the subsequent rapid water cooling, so that a supersaturated solid solution is formed. Tool withThe body process is as follows: when the temperature of the titanium alloy oil pipe blank is increased to the alpha+beta two-phase region, the beta 1 phase with higher content and larger size is remained due to the existence of the element (such as Al) for stabilizing the beta 0 phase, and the rest is converted into the beta 2 phase, and the remained beta 3 phase is named as the primary beta 5 phase. Since the beta 4 phase is a high temperature phase, the beta 8 phase such as a strip or needle is separated out due to instability in the subsequent cooling process, and the beta 9 phase is a secondary alpha phase. When the titanium alloy oil pipe blank is subjected to solution treatment, the size, the shape and the distribution of a primary alpha 2 phase are controlled through the alpha 1+ beta 6 dual-phase region, the rapid growth of beta 7 phase grains is avoided, a dual-state structure formed by mixing the primary phase and the secondary phase can be obtained, and the titanium alloy oil pipe has higher strength and toughness meeting the use conditions. Because the solution treatment is carried out in the alpha 3+alpha 0 dual-phase region, equiaxed alpha 6 phases and netlike alpha 7 phases are distributed on an alpha 4 phase matrix of the cold-rolled titanium alloy oil pipe blank in the solution process and can be partially converted into alpha 5 phases at high temperature, and the original equiaxed alpha 8 phases and netlike alpha 9 phases are partially converted into small and discontinuous spherical alpha phases in the conversion process. The reasonable aging temperature is selected later, so that the metastable beta phase which is not transformed in the water cooling process is decomposed, and the beta phase is transformed into a needle-shaped alpha 0 phase and a rod-shaped alpha 1 phase. As the formed spherical alpha 2 phase, the rod-shaped alpha phase and the needle-shaped alpha phase have different passivation and blocking capacities on crack tips in the crack propagation process, the forking or passivation of the crack tips is enhanced by controlling the spherical alpha phase proportion, the crack tip propagation deflection is enhanced by controlling the needle-shaped and rod-shaped alpha phase proportion, and the tortuosity and the negative force of the cracks are increased, so that the toughness of the material is improved.
The aging treatment temperature is in a relatively high temperature range of 560-600 ℃, so that the secondary alpha phase is tiny and needle-shaped in aging treatment and does not generate flaky alpha phase, dislocation movement can be prevented, the strength of the alloy is improved, a small amount of alpha phase is enabled to be dependent on the spherical alpha phase, the content of the spherical alpha phase is increased, the size of the spherical alpha phase is increased, and the plasticity and the toughness of the titanium alloy are improved to a certain extent. Compared with the traditional solid solution aging process, the invention can effectively regulate and control the contents and the sizes of spherical alpha phase, rod-shaped alpha phase and needle-shaped alpha phase in the microstructure of the titanium alloy oil pipe by reasonably selecting the process parameters on the basis of comprehensively considering the parameters such as heat treatment temperature, heating mode, heat preservation time, cooling mode and the like, thereby realizing good matching among strength, plasticity and toughness; the process flow is suitable for factory batch production equipment, and the process is simple and stable and convenient to operate.
Example 2
In example 2, a titanium alloy tube blank of 88.9x7.34 mm in specification was used, and the titanium alloy tube blank was a cold-rolled titanium alloy tube. The titanium alloy oil pipe blank comprises 0.1% of V, 3.8% of Al, 3% of Mo, 3.5% of Cr, 0.55% of Zr, 0.08% of Pd, 0.015% of C, 0.01% of H, 0.01% of O, 0.05% of N and 0.05% of Fe. The rolled structure of the titanium alloy oil pipe blank is that equiaxial alpha phases and netty alpha phases are distributed on a beta phase matrix, and the alpha phase content is less than or equal to 30 percent.
S1: heating a titanium alloy oil pipe blank with the specification of phi 88.9 multiplied by 7.34mm to 910 ℃ in a stepping continuous quenching furnace for solution treatment, wherein the heat preservation time is 1h, the heating rate is 21 ℃/min, and then cooling to room temperature by adopting a water cooling mode;
s2: and (3) heating the titanium alloy oil pipe blank subjected to solution treatment in the step (S1) to 560 ℃ in a step-type continuous tempering furnace for aging treatment, wherein the heat preservation time is 4 hours, and the heating rate is 21 ℃/min.
S3: after ageing treatment of the stepping continuous tempering furnace, conveying the titanium alloy oil pipe blank into a straightener through a roller way to carry out hot lift straightening, straightening at 455 ℃, and then cooling to room temperature in an air cooling mode on a cooling bed.
Example 3
In example 3, a titanium alloy tube blank of 88.9x7.34 mm in specification was used, and the titanium alloy tube blank was a cold-rolled titanium alloy tube. The titanium alloy oil pipe blank comprises 0.1% of V, 3.8% of Al, 3% of Mo, 3.0% of Cr, 0.6% of Zr, 0.08% of Pd, 0.012% of C, 0.01% of H, 0.008% of O, 0.05% of N and 0.02% of Fe. The rolled structure of the titanium alloy oil pipe blank is that equiaxial alpha phases and netty alpha phases are distributed on a beta phase matrix, and the alpha phase content is less than or equal to 30 percent.
S1: heating a titanium alloy oil pipe blank with the specification of phi 88.9 multiplied by 7.34mm to 910 ℃ in a stepping continuous quenching furnace for solution treatment, wherein the heat preservation time is 1h, the heating rate is 22 ℃/min, and then cooling to room temperature by adopting a water cooling mode;
s2: and (3) heating the titanium alloy oil pipe blank subjected to solution treatment in the step (S1) to 580 ℃ in a stepping continuous tempering furnace for aging treatment, wherein the heat preservation time is 4 hours, and the heating rate is 22 ℃/min.
S3: after ageing treatment of the stepping continuous tempering furnace, conveying the titanium alloy oil pipe blank into a straightener through a roller way to carry out hot lift straightening, straightening at 475 ℃, and then cooling to room temperature in an air cooling mode on a cooling bed.
Example 4
In example 4, a titanium alloy tube blank of 88.9x7.34 mm gauge was used, which was a cold rolled titanium alloy tube. The titanium alloy oil pipe blank comprises 0.08% of V, 3.5% of Al, 3.5% of Mo, 3.5% of Cr, 0.6% of Zr, 0.07% of Pd, 0.010% of C, 0.01% of H, 0.008% of O, 0.03% of N and 0.04% of Fe. The rolled structure of the titanium alloy oil pipe blank is that equiaxial alpha phases and netty alpha phases are distributed on a beta phase matrix, and the alpha phase content is less than or equal to 30 percent.
S1: heating a titanium alloy oil pipe blank with the specification of phi 88.9 multiplied by 7.34mm to 910 ℃ in a stepping continuous quenching furnace for solution treatment, wherein the heat preservation time is 1h, the heating rate is 23 ℃/min, and then cooling to room temperature by adopting a water cooling mode;
s2: and (3) heating the titanium alloy oil pipe blank subjected to solution treatment in the step (S1) to 600 ℃ in a stepping continuous tempering furnace for aging treatment, wherein the heat preservation time is 4 hours, the heating rate is 23 ℃/min, and then cooling to room temperature in an air cooling mode.
S3: after ageing treatment of the stepping continuous tempering furnace, conveying the titanium alloy oil pipe blank into a straightener through a roller way to carry out hot lift straightening, straightening the temperature to 485 ℃, and then cooling to room temperature in an air cooling mode on a cooling bed.
Example 5
In example 5, a titanium alloy tube blank of 88.9x7.34 mm gauge was used, which was a cold rolled titanium alloy tube. The titanium alloy oil pipe blank comprises 0.06% of V, 4.0% of Al, 2.5% of Mo, 3.0% of Cr, 0.6% of Zr, 0.08% of Pd, 0.012% of C, 0.01% of H, 0.01% of O, 0.04% of N and 0.05% of Fe. The rolled structure of the titanium alloy oil pipe blank is that equiaxial alpha phases and netty alpha phases are distributed on a beta phase matrix, and the alpha phase content is less than or equal to 30 percent.
S1: heating a titanium alloy oil pipe blank with the specification of phi 88.9 multiplied by 7.34mm to 910 ℃ in a stepping continuous quenching furnace for solution treatment, wherein the heat preservation time is 1h, the heating rate is 24 ℃/min, and then cooling to room temperature by adopting a water cooling mode;
s2: and (3) heating the titanium alloy oil pipe blank subjected to solution treatment in the step (S1) to 560 ℃ in a stepping continuous tempering furnace for aging treatment, wherein the heat preservation time is 2h, the heating rate is 24 ℃/min, and then cooling to room temperature in an air cooling mode.
S3: after ageing treatment of the stepping continuous tempering furnace, conveying the titanium alloy oil pipe blank into a straightener through a roller way to carry out hot lift straightening, straightening at 500 ℃, and then cooling to room temperature in an air cooling mode on a cooling bed.
Example 6
In example 6, a titanium alloy tube blank with a specification of phi 88.9x7.34 mm was used, and the titanium alloy tube blank was a cold-rolled titanium alloy tube. The titanium alloy oil pipe blank comprises 0.1% of V, 3.6% of Al, 3.2% of Mo, 3.3% of Cr, 0.5% of Zr, 0.09% of Pd, 0.012% of C, 0.008% of H, 0.01% of O, 0.04% of N and 0.04% of Fe. The rolled structure of the titanium alloy oil pipe blank is that equiaxial alpha phases and netty alpha phases are distributed on a beta phase matrix, and the alpha phase content is less than or equal to 30 percent.
S1: heating a titanium alloy oil pipe blank with the specification of phi 88.9 multiplied by 7.34mm to 910 ℃ in a stepping continuous quenching furnace for solution treatment, wherein the heat preservation time is 1h, the heating rate is 20 ℃/min, and then cooling to room temperature by adopting a water cooling mode;
s2: and (3) heating the titanium alloy oil pipe blank subjected to solution treatment in the step (S1) to 560 ℃ in a stepping continuous tempering furnace for aging treatment, wherein the heat preservation time is 8h, the heating rate is 20 ℃/min, and then cooling to room temperature in an air cooling mode.
S3: after ageing treatment of the stepping continuous tempering furnace, conveying the titanium alloy oil pipe blank into a straightener through a roller way to carry out hot lift straightening, straightening at the temperature of 460 ℃, and then cooling to room temperature in an air cooling mode on a cooling bed.
Example 7
In example 7, a titanium alloy tube blank of 88.9x7.34 mm in specification was used, and the titanium alloy tube blank was a cold-rolled titanium alloy tube. The titanium alloy oil pipe blank comprises 0.05% of V, 4.0% of Al, 2.5% of Mo, 3.5% of Cr, 0.5% of Zr, 0.08% of Pd, 0.010% of C, 0.005% of H, 0.008% of O, 0.04% of N and 0.03% of Fe. The rolled structure of the titanium alloy oil pipe blank is that equiaxial alpha phases and netty alpha phases are distributed on a beta phase matrix, and the alpha phase content is less than or equal to 30 percent.
S1: heating a titanium alloy oil pipe blank with the specification of phi 88.9 multiplied by 7.34mm to 830 ℃ in a stepping continuous quenching furnace for solution treatment, wherein the heat preservation time is 2 hours, the heating speed is 20 ℃/min, and then cooling to room temperature by adopting a water cooling mode;
s2: and (3) heating the titanium alloy oil pipe blank subjected to solution treatment in the step (S1) to 560 ℃ in a stepping continuous tempering furnace for aging treatment, wherein the heat preservation time is 4 hours, the heating rate is 20 ℃/min, and then cooling to room temperature in an air cooling mode.
S3: after ageing treatment of the stepping continuous tempering furnace, conveying the titanium alloy oil pipe blank into a straightener through a roller way to carry out hot lift straightening, straightening at 455 ℃, and then cooling to room temperature in an air cooling mode on a cooling bed.
Examples 2 to 7 the heat treatment process and the toughness of the heat treated titanium alloy oil pipe blank are shown in table 1, wherein three test samples were taken for each example to test the tensile strength, yield strength and toughness, and the average value of the three samples was recorded as the result in table 1. As can be seen from Table 1, the yield strength of the titanium alloy oil pipe blank is 855 MPa-880 MPa, the tensile strength is 930MPa-950 MPa, and the full-size impact energy at-10 ℃ is 56J-73J. Comparing Table 2, wherein the yield strength of the tube blank before being treated by the heat treatment process is within the range of 790MPa-8235 MPa, the tensile strength is within the range of 865 MPa-910 MPa, and the lowest value of full-size impact energy is 45J at-10 ℃; and after heat treatment, the yield strength of the tube blank ranges from 855MPa to 840 MPa, the tensile strength of the tube blank ranges from 930MPa to 950MPa, the minimum value of the full-size impact energy is 56J at the temperature of minus 10 ℃, wherein the minimum value of the actual yield strength is improved by about 8 percent, the minimum value of the tensile strength is more than or equal to 930MPa, the minimum value of the full-size impact toughness is improved by more than 20 percent, and the good toughness matching of the titanium alloy tube is realized.
Fig. 1 to 6 show the microstructure of the titanium alloy oil pipe in examples 2 to 7 of the present invention, and it can be seen from the figures that, after the process treatment with different temperature and time parameters, the α phase is mainly spherical α phase, and also the rod-like α phase, the needle-like α phase and the bar-like α phase are equal, and the flaky α phase does not appear, wherein the α phase in fig. 1 is 14.1%, the α phase in fig. 2 is 15.9%, the α phase in fig. 3 is 17.5%, the α phase in fig. 4 is 11.5%, the α phase in fig. 5 is 14.8%, and the α phase in fig. 6 is 25.2%. The aging treatment temperature is in a relatively high temperature range of 560-600 ℃, so that secondary precipitated alpha phases are tiny and needle-shaped during aging treatment, and flaky alpha phases are not generated, thereby preventing dislocation movement, improving the strength of the alloy, simultaneously enabling a small amount of alpha phase to be dependent on spherical alpha phases, increasing the content of the spherical alpha phases and growing the size of the spherical alpha phases, and further improving the plasticity and toughness of the titanium alloy to a certain extent.
Table 1 heat treatment process and strength of titanium alloy oil pipe blank
TABLE 2 Strength of titanium alloy tubing tube blank before Heat treatment Process
The present invention is not limited to the above-mentioned embodiments, and any changes or substitutions that can be easily understood by those skilled in the art within the technical scope of the present invention are intended to be included in the scope of the present invention.
Claims (5)
1. A heat treatment method of a high-toughness titanium alloy oil pipe is characterized by comprising the following steps: the oil pipe comprises the following chemical element components in percentage by weight: al:3.5% -4.0%, mo:2.5% -3.5%, cr:3.0% -3.5%, zr:0.5 to 0.6 percent, pd less than or equal to 0.1 percent, V less than or equal to 0.1 percent, C less than or equal to 0.015 percent, H less than or equal to 0.01 percent, O less than or equal to 0.01 percent, N less than or equal to 0.05 percent, fe less than or equal to 0.05 percent, and the balance of Ti and unavoidable impurities, comprising the following steps:
s1: carrying out solution treatment on the titanium alloy oil pipe blank, wherein the specific process is as follows:
the cold rolling state structure of the titanium alloy oil pipe blank is that equiaxial alpha phase and net alpha phase are distributed on a beta phase matrix, the alpha phase content is less than or equal to 30 percent, and the cold rolling state titanium alloy oil pipe blank is heated to beta phase transition temperature T in a stepping continuous quenching furnace β Preserving the temperature at 30-110 ℃ for 1-2 hours, and then cooling to room temperature by adopting a water cooling mode;
s2: aging the titanium alloy oil pipe blank; the specific process is as follows:
heating the titanium alloy oil pipe blank cooled after solution treatment in the step S1 to 560-600 ℃ in a step-by-step continuous tempering furnace, and preserving heat for 2-8 hours; the structure form of the titanium alloy oil pipe blank after the aging treatment process in the step S2 is that discontinuous spherical alpha phase, rod-shaped alpha phase and needle-shaped alpha phase are distributed on a beta phase matrix, the content of the alpha phase is less than or equal to 30%, and the content of the spherical alpha phase is more than 10%;
s3: carrying out heat car straightening treatment on the titanium alloy oil pipe blank; the specific process is as follows:
and (3) conveying the titanium alloy oil pipe blank subjected to ageing treatment in the step-by-step continuous tempering furnace in the step (S2) into a straightener through a roller way to carry out hot lift straightening, straightening at a temperature of more than 450 ℃, and then cooling to room temperature in an air cooling mode on a cooling bed.
2. The heat treatment method of the high-strength and high-toughness titanium alloy oil pipe, according to claim 1, is characterized in that: and in the step S1, the titanium alloy oil pipe blank is subjected to solution treatment, and the cold-rolled titanium alloy oil pipe blank is heated to a heating temperature of 830-910 ℃ in a step-type continuous quenching furnace.
3. The heat treatment method of the high-strength and high-toughness titanium alloy oil pipe, according to claim 1, is characterized in that: and (2) the heating speed of the step-type continuous quenching furnace in the step S1 is 20-25 ℃/min.
4. The heat treatment method of the high-strength and high-toughness titanium alloy oil pipe, according to claim 1, is characterized in that: and (2) heating the furnace at a heating speed of 20-25 ℃/min in the heating process of the step-type continuous tempering furnace.
5. The heat treatment method of the high-strength and high-toughness titanium alloy oil pipe, according to claim 1, is characterized in that: and (2) after the aging treatment process in the step (S2), the yield strength of the titanium alloy oil pipe blank is 855-840 MPa, the tensile strength is 930-950 MPa, and the full-size impact energy at the temperature of minus 10 ℃ is 56-73J.
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