A heat treatment method suitable for Ti2AlNb alloy electron beam welding

Abstract

The present application relates to the technical field of welding, in particular to a heat treatment method suitable for Ti2AlNb alloy electron beam welding.A heat treatment method suitable for Ti2AlNb alloy electron beam welding, comprising the following steps: (a) solid solution heat treatment is carried out on Ti2AlNb alloy forgings, PAG cooling liquid is used for cooling, and then stress relief annealing treatment is carried out, so that pretreated forgings are obtained; (b) the pretreated forgings are subjected to electron beam welding, and after electron beam welding, gas quenching is used, so that welded parts are obtained; (c) the welded parts are subjected to aging treatment, and after aging treatment, gas quenching is used, so that Ti2AlNb alloy welded parts are obtained.The heat treatment method suitable for Ti2AlNb alloy electron beam welding of the present application can obtain double strip structure with excellent comprehensive performance through cooperation of each step, and can improve the room temperature and high temperature tensile properties of Ti2AlNb alloy welded parts.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of welding, in particular to a heat treatment method suitable for Ti2AlNb alloy electron beam welding. BACKGROUND

[0002] Ti2AlNb alloy is a typical intermetallic compound, which has the intrinsic characteristics of high strength and poor plasticity. One of the important factors restricting its engineering application is welding. The performance of Ti2AlNb alloy is different under different heat treatment states. The method adopted in the prior art is that the room temperature plasticity of Ti2AlNb alloy is poor, and the weldability is poor.

[0003] Therefore, how to effectively perform heat treatment during the welding process of Ti2AlNb alloy forgings is crucial to enable the Ti2AlNb alloy forgings to have excellent welding performance.

[0004] Therefore, the present application is proposed. SUMMARY

[0005] An object of the present application is to provide a heat treatment method suitable for Ti2AlNb alloy electron beam welding to solve the above technical problems. The method can obtain a double ribbon structure with excellent comprehensive performance, thereby facilitating improvement of the comprehensive mechanical properties of Ti2AlNb alloy weldments.

[0006] In order to achieve the above object of the present application, the following technical solutions are adopted:

[0007] A heat treatment method suitable for Ti2AlNb alloy electron beam welding, comprising the following steps:

[0008] (a) performing solid solution heat treatment on Ti2AlNb alloy forgings, cooling by using PAG cooling liquid, and then performing stress relief annealing treatment to obtain a pretreated forging;

[0009] (b) performing electron beam welding on the pretreated forging, and then performing gas quenching after the electron beam welding to obtain a welded part;

[0010] (c) performing aging treatment on the welded part, and then performing gas quenching after the aging treatment to obtain a Ti2AlNb alloy weldment.

[0011] In some embodiments, the temperature of the solid solution heat treatment is 900-1000℃, and the time of the solid solution heat treatment is 1-4h.

[0012] In some embodiments, the temperature of the solid solution heat treatment is 930-980℃, and the time of the solid solution heat treatment is 1.5-3h.

[0013] In some embodiments, the concentration of the PAG cooling liquid is 18%-22%.

[0014] In some embodiments, the temperature of the stress relief annealing treatment is 350-500 °C, and the time of the stress relief annealing treatment is 2-6 h.

[0015] In some embodiments, the temperature of the stress relief annealing treatment is 400-460 °C, and the time of the stress relief annealing treatment is 2-5 h.

[0016] In some embodiments, the microstructure of the pre-treated forging includes B2 phase, O phase and a2 phase, the volume fraction of the B2 phase is 65-90%, and the total volume fraction of the O phase and a2 phase is 10-35%.

[0017] In some embodiments, the room temperature plasticity of the pre-treated forging is 16-20%.

[0018] In some embodiments, the welding surface of the pre-treated forging includes a rectangular ring with an outer diameter of 200-300 mm.

[0019] In some embodiments, the pre-treated forging is further subjected to rough machining before the electron beam welding, and the rough machining includes thinning the wall thickness of the welding site of the pre-treated forging to 5-8 mm.

[0020] In some embodiments, the acceleration voltage of the electron beam welding is 130-160 kV, the electron beam current is 7-12 mA, and the welding speed is 10-15 m / s.

[0021] In some embodiments, in step (b), the gas pressure for gas quenching is 0.7-1 bar.

[0022] In some embodiments, the temperature of the aging treatment is 750-900 °C, and the time of the aging treatment is 6-24 h.

[0023] In some embodiments, the temperature of the aging treatment is 800-870 °C, and the time of the aging treatment is 8-16 h.

[0024] In some embodiments, in step (c), the gas pressure for gas quenching is 0.7-1 bar.

[0025] In some embodiments, the microstructure of the Ti2AlNb alloy weldment includes B2 phase, O phase and a2 phase, the volume fraction of the B2 phase is 5-30%, the O phase and a2 phase include large laths and small laths, the length of the large laths is 1-5 μm, the total volume fraction of the O phase and a2 phase of the large laths is 10-35%, the length of the small laths is less than 1 μm, and the total volume fraction of the O phase and a2 phase of the small laths is 35-60%.

[0026] In some embodiments, the Ti2AlNb alloy weldment has a tensile strength of 1020-1100 MPa, a yield strength of 960-1050 MPa, an elongation of 6%-10%, and a reduction of area of 8%-15% at 25℃.

[0027] In some embodiments, the Ti2AlNb alloy weldment has a tensile strength of 840-900 MPa, a yield strength of 700-800 MPa, an elongation of 11%-25%, and a reduction of area of 26%-80% at 650℃.

[0028] Compared with the prior art, the present application has the following beneficial effects:

[0029] The heat treatment method for electron beam welding of the Ti2AlNb alloy of the present application, by solid solution heat treatment, PAG cooling liquid cooling, and stress relief annealing treatment of the Ti2AlNb alloy forge piece, the microstructure of the obtained pretreated forge piece has a suitable volume percentage of B2 phase, O phase and α2 phase, has excellent room temperature plasticity, and further ensures the smooth progress of subsequent electron beam welding, improves the welding effect of electron beam welding; further aging treatment of the welded piece, and further obtaining a double-lath structure with excellent comprehensive performance, to improve the room temperature and high temperature tensile properties of the Ti2AlNb alloy weldment. BRIEF DESCRIPTION OF DRAWINGS

[0030] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the description of the embodiments or the prior art. Obviously, the drawings described below are some embodiments of the present application, and those skilled in the art can also obtain other drawings according to these drawings without creative labor.

[0031] Figure 1 The microstructure diagram of the pretreated forge piece in Example 1 of the present application;

[0032] Figure 2 The microstructure diagram of the Ti2AlNb alloy weldment in Example 1 of the present application. DETAILED DESCRIPTION

[0033] The embodiments of the present application will be described in detail below with reference to the examples, but those skilled in the art will understand that the following examples are only used to illustrate the present application and should not be regarded as limiting the scope of the present application. The specific conditions are not specified in the examples, and the conventional conditions or the conditions recommended by the manufacturer are used. The reagents or instruments used are not specified by the manufacturer, and are all conventional products that can be obtained by purchase.

[0034] A heat treatment method suitable for Ti2AlNb alloy electron beam welding, comprising the following steps:

[0035] (a) The Ti2AlNb alloy forgings are subjected to solid solution heat treatment, cooled by PAG cooling liquid, and then subjected to stress relief annealing treatment to obtain pretreated forgings.

[0036] (b) The pretreated forgings are subjected to electron beam welding, and after electron beam welding, gas quenching is used to obtain welded parts.

[0037] (c) The welded parts are subjected to aging treatment, and after aging treatment, gas quenching is used to obtain Ti2AlNb alloy welded parts.

[0038] The heat treatment method suitable for Ti2AlNb alloy electron beam welding of the application, by solid solution heat treatment, PAG cooling liquid cooling and stress relief annealing treatment of the Ti2AlNb alloy forgings, the microstructure of the obtained pretreated forgings has a suitable volume percentage of B2 phase, O phase and α2 phase, has excellent room temperature plasticity, and further ensures the smooth progress of subsequent electron beam welding, improves the welding effect of electron beam welding; further aging treatment of the welded parts, and further obtain double strip structure with excellent comprehensive performance, to improve the room temperature and high temperature tensile properties of Ti2AlNb alloy welded parts, and good comprehensive mechanical properties.

[0039] In some embodiments, the Ti2AlNb alloy forgings are Ti2AlNb ring forgings prepared by ring rolling. In some embodiments, the Ti2AlNb alloy in specific examples and comparative examples is Ti-22Al-25Nb. In some embodiments, the Ti2AlNb alloy can be obtained by conventional melting, forging and hot rolling process. The method of the application is also suitable for Ti2AlNb alloys containing one or more of Mo, Si, Cr, V, Fe and Ta alloying elements.

[0040] In some embodiments, the Ti2AlNb alloy forgings are heated to a certain temperature before entering the furnace. The solid solution heat treatment temperature is 900-1000℃, including but not limited to 900℃, 910℃, 920℃, 930℃, 940℃, 950℃, 960℃, 970℃, 980℃, 990 or 1000℃, or any range between any two of them. The solid solution heat treatment time is 1-4h, such as 1h, 1.5h, 2h, 2.5h, 3h, 3.5h or 4h, or any range between any two of them. Preferably, the solid solution heat treatment temperature is 930-980℃, and the solid solution heat treatment time is 1.5-3h. The application uses appropriate solid solution heat treatment conditions to fully dissolve various phases in the alloy, strengthen the solid solution, and improve the weldability of the Ti2AlNb alloy forgings.

[0041] In some embodiments, the concentration (mass content) of the PAG cooling liquid is 18% to 22%, such as 18%, 19%, 20%, or 22%, etc. The PAG cooling liquid comprises PAG and water. The organic polymer in the PAG cooling liquid is completely dissolved in water to form a clear and homogeneous solution. During the quenching process of the Ti2AlNb alloy forge piece, once the liquid temperature around the workpiece rises above the cloud point of the solution, the PAG polymer will be desorbed from the solution and suspended in the quenching liquid in the form of fine liquid beads. As soon as the suspended PAG liquid beads come into contact with the red-hot workpiece, they will adhere to the surface of the workpiece due to their excellent wettability, forming a water-rich film that wraps around the workpiece. This film adjusts the cooling speed of the water to prevent the workpiece from cracking during quenching. The PAG solution can overcome the shortcomings of water cooling, such as fast cooling speed, easy cracking of the workpiece, and oil products, such as slow cooling speed, poor quenching effect, and flammability. Specifically, the concentration of the PAG cooling liquid in each embodiment is 20%.

[0042] In some embodiments, the temperature of the stress relief annealing treatment is 350 to 500°C, including but not limited to 400°C, 410°C, 420°C, 430°C, 440°C, 450°C, 460°C, 470°C, 480°C, 490°C, 500°C, etc., or a range value between any two thereof. The time of the stress relief annealing treatment is 2 to 6h, such as 2h, 3h, 4h, 5h, 6h, etc. Preferably, the temperature of the stress relief annealing treatment is 400 to 460°C, and the time of the stress relief annealing treatment is 2 to 5h. The present application ensures the stress relief effect before welding through the stress relief annealing treatment under suitable conditions, so as to obtain a pretreated forge piece with suitable mechanical properties.

[0043] In some embodiments, the microstructure of the pretreated forge piece comprises B2 phase, O phase, and α2 phase. The volume fraction of the B2 phase is 65% to 90%, including but not limited to 65%, 70%, 75%, 80%, 85%, 90%, etc., or a range value between any two thereof. The total volume fraction of the O phase and the α2 phase is 10% to 35%, including but not limited to 10%, 15%, 20%, 25%, 30%, 35%, etc., or a range value between any two thereof. The present application controls the suitable volume fraction of the B2 phase, so as to make the pretreated forge piece have excellent plasticity. The room temperature plasticity of the pretreated forge piece is 16% to 20%, which is beneficial to electron beam welding and improves the welding performance.

[0044] In some embodiments, the welding surface of the pretreated forge piece comprises a rectangular ring with an outer diameter size of 200 to 300mm, such as 200mm, 220mm, 250mm, 300mm, etc.

[0045] In some embodiments, the pre-processed forging is further subjected to rough machining before the electron beam welding to facilitate the subsequent electron beam welding, the rough machining comprising: thinning the wall thickness of the to-be-welded part of the pre-processed forging to 5-8 mm, such as 5 mm, 6 mm, 7 mm, 8 mm, etc.

[0046] In some embodiments, the electron beam welding is performed at an acceleration voltage of 130-160 kv, such as 130 kv, 140 kv, 150 kv, 160 kv, etc. The electron beam current is 7-12 mA, such as 7 mA, 8 mA, 10 mA, or 12 mA, etc. The welding speed is 10-15 m / s, such as 10 m / s, 12 m / s, 15 m / s, etc. In step (b), after the electron beam welding, gas quenching is performed to ensure the microstructure characteristics and performance of the welded part, and the gas pressure for the gas quenching is 0.7-1 bar, such as 0.7 bar, 0.75 bar, 0.8 bar, 0.85 bar, 0.9 bar, 1 bar, etc. The gas used for the gas quenching includes argon and / or helium. The gas quenching is performed at a suitable pressure to ensure the microstructure characteristics and mechanical performance of the welded part.

[0047] In some embodiments, the aging treatment is performed at a temperature of 750-900 ℃, including but not limited to 750 ℃, 780 ℃, 800 ℃, 810 ℃, 830 ℃, 850 ℃, 880 ℃, or 900 ℃, etc., or a range value between any two of them. The aging treatment is performed for a time of 6-24 h, such as 10 h, 11 h, 12 h, 13 h, 14 h, 15 h, 16 h, 17 h, 18 h, 19 h, 20 h, etc. Preferably, the aging treatment is performed at a temperature of 800-870 ℃, and the aging treatment is performed for a time of 8-16 h. In step (c), the gas pressure for the gas quenching is 0.7-1 bar, such as 0.7 bar, 0.8 bar, 0.9 bar, 1 bar, etc., or a range value between any two of them. The present application further uses suitable aging treatment and gas quenching after the above-mentioned solution heat treatment, cooling, holding, electron beam welding, and gas quenching, so that the microstructure of the Ti2AlNb alloy forging has a suitable volume fraction of B2 phase, O phase, and α2 phase, to provide excellent strength.

[0048] In some embodiments, the microstructure of the Ti2AlNb alloy weldment comprises B2 phase, O phase and a2 phase, the volume fraction of the B2 phase is 5% to 30%, for example, 5%, 10%, 15%, 20%, 25%, 30%, or a range between any two of them; the O phase and a2 phase comprise large lath O phase and a2 phase and small lath O phase and a2 phase, the length of the large lath O phase and a2 phase is 1 to 5 μm, for example, 1 μm, 2 μm, 3 μm, 4 μm or 5 μm, or a range between any two of them; the total volume fraction of the large lath O phase and a2 phase is 10% to 35%, for example, 10%, 15%, 20%, 25%, 30% or 35%, or a range between any two of them; the length of the small lath O phase and a2 phase is less than 1 μm, for example, 0.01 μm, 0.02 μm, 0.05 μm, 0.08 μm, 0.1 μm, 0.2 μm, 0.3 μm, 0.4 μm, 0.5 μm, 0.6 μm, 0.7 μm, 0.9 μm, 0.95 μm, or a range between any two of them; the total volume fraction of the small lath O phase and a2 phase is 35% to 60%, for example, 35%, 40%, 45%, 50%, 55%, 60%, or a range between any two of them. The microstructure of the weldment of the present application has appropriate volume fractions of B2 phase, O phase and a2 phase, the O phase and a2 phase have appropriate volume fractions, large lath O phase and a2 phase and small lath O phase and a2 phase of appropriate size, which cooperate to ensure that the weldment has excellent mechanical properties.

[0049] In some embodiments, the Ti2AlNb alloy weldment has a tensile strength of 1020 to 1100 MPa at 25°C, for example, 1020 MPa, 1040 MPa, 1050 MPa, 1070 MPa, 1080 MPa, 1100 MPa, or a range between any two of them. The yield strength is 960 to 1050 MPa, for example, 960 MPa, 1000 MPa, 1050 MPa, the elongation is 6% to 10%, for example, 6%, 7.5%, 8%, 8.5%, 9%, 10%, or a range between any two of them; the reduction of area is 8% to 15%, for example, 8%, 10%, 11%, 12%, 13%, 14%, 15%, or a range between any two of them.

[0050] In some embodiments, the Ti2AlNb alloy weldment has a tensile strength at 650℃ of 840-900 MPa, such as 840 MPa, 850 MPa, 860 MPa, 870 MPa, 880 MPa, 890 MPa, 900 MPa, or any range between any two of these values; a yield strength of 700-800 MPa, such as 700 MPa, 710 MPa, 730 MPa, 750 MPa, 770 MPa, 780 MPa, 800 MPa, or any range between any two of these values; an elongation of 11-25%, such as 11%, 15%, 20%, 21%, 22%, 23%, 24%, 25%, or any range between any two of these values; and a reduction of area of 26-80%, such as 26%, 55%, 60%, 65%, 70%, 75%, 80%, or any range between any two of these values. The Ti2AlNb alloy weldment obtained by the method of the present application has excellent mechanical properties at room temperature and at high temperature.

[0051] The application will be further explained in connection with specific examples and comparative examples.

[0052] Example 1

[0053] A heat treatment method suitable for electron beam welding of Ti2AlNb alloy, comprising the following steps:

[0054] (1) Ring rolling Ti2AlNb ring forgings.

[0055] (2) The Ti2AlNb alloy forgings are subjected to solid solution heat treatment, the temperature of the solid solution heat treatment is 970℃, the time of the solid solution heat treatment is 2.5h, after the solid solution heat treatment, the forgings are cooled using PAG cooling liquid, and then subjected to stress relief annealing treatment, the temperature of the stress relief annealing treatment is 455℃, the time of the stress relief annealing treatment is 3h, to obtain pre-processed forgings. The microstructure of the pre-processed forgings is shown in Figure 1 .

[0056] (3) The pre-processed forgings are subjected to rough machining before welding, the wall thickness of the electron beam welding is uniformly thinned to 6mm, the welding surface is a rectangular ring, the outer diameter size

[0057] (4) The pre-processed forgings after rough machining are subjected to electron beam welding, the acceleration voltage of the electron beam welding is 150kv, the electron beam current is 10mA, and the welding speed is 13m / s. After the electron beam welding, gas quenching is used, the gas used for gas quenching is argon, and the gas pressure is 0.85bar, to obtain a welded piece.

[0058] (5) aging treatment is performed on the welded piece, the temperature of the aging treatment is 840 DEG C, the time of the aging treatment is 12h; after the aging treatment, gas quenching is adopted, the gas for the gas quenching is argon, the gas pressure for the gas quenching is 0.85bar, a Ti2AlNb alloy welded piece is obtained, and a microstructure diagram of the Ti2AlNb alloy welded piece is as shown in Figure 2

[0059] Example 2

[0060] A heat treatment method suitable for electron beam welding of a Ti2AlNb alloy, comprising the following steps:

[0061] (1) a Ti2AlNb ring forging piece is prepared by ring rolling.

[0062] (2) solid solution heat treatment is performed on the Ti2AlNb alloy forging piece, the temperature of the solid solution heat treatment is 930 DEG C, the time of the solid solution heat treatment is 3h, after the solid solution heat treatment, PAG cooling liquid is adopted for cooling, and then stress relief annealing treatment is performed, the temperature of the stress relief annealing treatment is 430 DEG C, the time of the stress relief annealing treatment is 2h, and a pretreated forging piece is obtained.

[0063] (3) the pretreated forging piece is subjected to rough machining before welding, the wall thickness of the electron beam welding is uniformly reduced to 6mm, the welding surface is a rectangular ring, the outer diameter size of the welding surface is 100mm, and the inner diameter size of the welding surface is 90mm.

[0064] (4) electron beam welding is performed on the pretreated forging piece after the rough machining, the acceleration voltage of the electron beam welding is 150kv, the electron beam current is 10mA, and the welding speed is 13m / s. After the electron beam welding, gas quenching is adopted, the gas for the gas quenching is argon, and the gas pressure is 0.9bar, and a welded piece is obtained.

[0065] (5) aging treatment is performed on the welded piece, the temperature of the aging treatment is 800 DEG C, the time of the aging treatment is 13h; after the aging treatment, gas quenching is adopted, the gas for the gas quenching is argon, the gas pressure for the gas quenching is 0.9bar, and a Ti2AlNb alloy welded piece is obtained.

[0066] Example 3

[0067] A heat treatment method suitable for electron beam welding of a Ti2AlNb alloy, comprising the following steps:

[0068] (1) a Ti2AlNb ring forging piece is prepared by ring rolling.

[0069] ​(2) The Ti2AlNb alloy forging is subjected to solid solution heat treatment, the temperature of the solid solution heat treatment is 980 DEG C, the time of the solid solution heat treatment is 1.5 h, after the solid solution heat treatment, the PAG cooling liquid is used for cooling, then the heat preservation stress relief annealing treatment is carried out, the temperature of the heat preservation stress relief annealing treatment is 400 DEG C, the time of the heat preservation stress relief annealing treatment is 6 h, and the pretreated forging is obtained.

[0070] (3) The pretreated forging is subjected to rough machining before welding, the wall thickness of the electron beam welding is uniformly thinned to 6 mm, the welding surface is a rectangular ring, the outer diameter size of the welding surface is 100 mm, and the inner diameter size of the welding surface is 60 mm.

[0071] (4) The pretreated forging after the rough machining is subjected to electron beam welding, the acceleration voltage of the electron beam welding is 150 kv, the electron beam current is 10 mA, and the welding speed is 13 m / s. After the electron beam welding, the gas quenching is carried out, the gas of the gas quenching is argon, and the gas pressure of the gas quenching is 0.8 bar, and the welded piece is obtained.

[0072] (5) The welded piece is subjected to aging treatment, the temperature of the aging treatment is 870 DEG C, the time of the aging treatment is 13 h, after the aging treatment, the gas quenching is carried out, the gas of the gas quenching is argon, and the gas pressure of the gas quenching is 0.8 bar, and the Ti2AlNb alloy welded piece is obtained.

[0073] Example 4

[0074] A heat treatment method suitable for Ti2AlNb alloy electron beam welding, comprising the following steps:

[0075] (1) The Ti2AlNb ring forging is prepared by ring rolling.

[0076] (2) The Ti2AlNb alloy forging is subjected to solid solution heat treatment, the temperature of the solid solution heat treatment is 900 DEG C, the time of the solid solution heat treatment is 3 h, after the solid solution heat treatment, the PAG cooling liquid is used for cooling, then the heat preservation stress relief annealing treatment is carried out, the temperature of the heat preservation stress relief annealing treatment is 400 DEG C, the time of the heat preservation stress relief annealing treatment is 1 h, and the pretreated forging is obtained.

[0077] (3) The pretreated forging is subjected to rough machining before welding, the wall thickness of the electron beam welding is uniformly thinned to 6 mm, the welding surface is a rectangular ring, the outer diameter size of the welding surface is 100 mm, and the inner diameter size of the welding surface is 60 mm.

[0078] (4) The pretreated forging after the rough machining is subjected to electron beam welding, the acceleration voltage of the electron beam welding is 150 kv, the electron beam current is 10 mA, and the welding speed is 13 m / s. After the electron beam welding, the gas quenching is carried out, the gas of the gas quenching is argon, and the gas pressure of the gas quenching is 0.7 bar, and the welded piece is obtained.

[0079] (5) aging treatment is performed on the welded piece, the temperature of the aging treatment is 750℃, the time of the aging treatment is 20h; after the aging treatment, gas quenching is performed, the gas for the gas quenching is argon, the gas pressure for the gas quenching is 0.7bar, and a Ti2AlNb alloy welded piece is obtained.

[0080] Example 5

[0081] A heat treatment method suitable for electron beam welding of a Ti2AlNb alloy, comprising the following steps:

[0082] (1) A Ti2AlNb ring forging piece is prepared by ring rolling.

[0083] (2) The Ti2AlNb alloy forging piece is subjected to solid solution heat treatment, the temperature of the solid solution heat treatment is 1000℃, the time of the solid solution heat treatment is 3h, and after the solid solution heat treatment, PAG cooling liquid is used for cooling, and then stress relief annealing treatment is performed, the temperature of the stress relief annealing treatment is 500℃, the time of the stress relief annealing treatment is 1h, and a pretreated forging piece is obtained.

[0084] (3) The pretreated forging piece is subjected to rough machining before welding, the wall thickness of the electron beam welding is uniformly thinned to 6mm, the welding surface is a rectangular ring, the outer diameter size of the welding surface is 100mm, and the inner diameter size of the welding surface is 60mm.

[0085] (4) The pretreated forging piece after the rough machining is subjected to electron beam welding, the acceleration voltage of the electron beam welding is 150kv, the electron beam current is 10mA, and the welding speed is 13m / s. After the electron beam welding, gas quenching is performed, the gas for the gas quenching is argon, and the gas pressure is 1bar, and a welded piece is obtained.

[0086] (5) Aging treatment is performed on the welded piece, the temperature of the aging treatment is 900℃, the time of the aging treatment is 10h; after the aging treatment, gas quenching is performed, the gas for the gas quenching is argon, the gas pressure for the gas quenching is 1bar, and a Ti2AlNb alloy welded piece is obtained.

[0087] Comparative Example 1

[0088] A heat treatment method suitable for electron beam welding of a Ti2AlNb alloy, comprising the following steps:

[0089] (1) A Ti2AlNb ring forging piece is prepared by ring rolling.

[0090] (2) The Ti2AlNb alloy forging piece is subjected to solid solution heat treatment, the temperature of the solid solution heat treatment is 1000℃, the time of the solid solution heat treatment is 3h, and after the solid solution heat treatment, PAG cooling liquid is used for cooling, and then stress relief annealing treatment is performed, the temperature of the stress relief annealing treatment is 500℃, the time of the stress relief annealing treatment is 1h, and a pretreated forging piece is obtained.

[0091] (3) the pre-processed forging is rough machined, and the wall thickness of the electron beam welding is uniformly reduced to 6 mm, the welding surface is a rectangular ring, and the outer diameter size

[0092] (4) the pre-processed forging after rough machining is electron beam welded, the acceleration voltage of the electron beam welding is 150 kv, the electron beam current is 10 mA, and the welding speed is 13 m / s. After electron beam welding, air cooling is adopted to obtain the Ti2AlNb alloy welding piece.

[0093] Comparative Example 2

[0094] A heat treatment method for electron beam welding of a Ti2AlNb alloy, which is different from that of Example 1, comprises the following steps:

[0095] In step (2), air cooling is adopted after the solution heat treatment.

[0096] Experimental Example

[0097] I. Microstructure of the pre-processed forging and room temperature plasticity

[0098] The volume fractions of B2 phase, O phase and α2 phase in the microstructure of the pre-processed forging of each example and comparative example, and the room temperature plasticity of the pre-processed forging are shown in Table 1.

[0099] Table 1 Microstructure of the pre-processed forging and room temperature plasticity

[0100] Group B2 phase (%) O phase and a2 phase (%) Room temperature plasticity (%) Example 1 88 12 20 Example 2 65 35 17 Example 3 85 15 18 Example 4 55 45 16 Example 5 92 8 16 Comparative Example 1 32 68 8 Comparative Example 2 30 70 7

[0101] As shown in Table 1, by means of the solution heat treatment under suitable conditions, the PAG cooling liquid cooling and the stress relief annealing treatment, the pre-processed forging obtained has the B2 phase, O phase and α2 phase with suitable volume fractions in the microstructure, which can ensure the plasticity of the pre-processed forging and is beneficial to the subsequent electron beam welding and improves the welding performance.

[0102] II. Microstructure of the Ti2AlNb alloy welding piece and room temperature plasticity

[0103] The total volume fractions of B2 phase, O phase and α2 phase in the microstructure of the Ti2AlNb alloy welding piece of each example and comparative example, and the room temperature plasticity of the pre-processed forging are shown in Table 2.

[0104] Table 2 Microstructure of the Ti2AlNb alloy welding piece and room temperature plasticity

[0105]

[0106]

[0107] III. Mechanical properties of the Ti2AlNb alloy welding piece

[0108] The Ti2AlNb alloy welding pieces of each embodiment and the comparative example were subjected to mechanical property testing. The room temperature tensile standard was GB228.1. The high temperature tensile was GB228.2.

[0109] The mechanical property testing results of the Ti2AlNb alloy welding pieces are shown in Table 3.

[0110] Table 3 Mechanical property testing results of the Ti2AlNb alloy welding pieces

[0111]

[0112]

[0113] As can be seen from Table 2 and Table 3, the microstructure of the welding piece of the present application has a suitable volume fraction of B2 phase, O phase and α2 phase, the O phase and α2 phase have a suitable total volume fraction, size of large lath O phase and α2 phase and small lath O phase and α2 phase, and the large lath O phase and α2 phase and the small lath O phase and α2 phase coordinate with each other, thereby ensuring that the welding piece has excellent room temperature and high temperature tensile properties.

[0114] Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present application, and not to limit them; although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that: it can still modify the technical solutions recorded in the foregoing embodiments, or make equivalent replacement to part or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A heat treatment method suitable for electron beam welding of Ti2AlNb alloy, characterized in that, The method comprises the following steps: (a) solid solution heat treatment is performed on a Ti2AlNb alloy forge piece, PAG cooling liquid is used for cooling, and then stress relief annealing treatment is performed after holding, to obtain a pretreated forge piece; (b) electron beam welding is performed on the pretreated forge piece, and gas quenching is performed after electron beam welding, to obtain a welded piece; (c) aging treatment is performed on the welded piece, and gas quenching is performed after aging treatment, to obtain a Ti2AlNb alloy welded piece; The temperature of the solid solution heat treatment is 900-1000℃, and the time of the solid solution heat treatment is 1-4h; The temperature of the stress relief annealing treatment is 350-500℃, and the time of the stress relief annealing treatment is 2-6h; The temperature of the aging treatment is 750-900℃, and the time of the aging treatment is 6-24h.

2. The heat treatment method suitable for Ti2AlNb alloy electron beam welding according to claim 1, characterized in that, The temperature of the solid solution heat treatment is 930-980℃, and the time of the solid solution heat treatment is 1.5-3h.

3. The heat treatment method suitable for Ti2AlNb alloy electron beam welding according to claim 1, characterized in that, The concentration of the PAG cooling liquid is 18%-22%.

4. The heat treatment method suitable for Ti2AlNb alloy electron beam welding according to claim 1, characterized in that, The temperature of the stress relief annealing treatment is 400-460℃, and the time of the stress relief annealing treatment is 2-5h.

5. The heat treatment method suitable for Ti2AlNb alloy electron beam welding according to claim 1, characterized in that, The microstructure of the pretreated forge piece comprises B2 phase, O phase and α2 phase, the volume fraction of the B2 phase is 55%-90%, and the total volume fraction of the O phase and the α2 phase is 10%-45%; And / or, the room temperature plasticity of the pretreated forge piece is 16%-20%.

6. The heat treatment method suitable for Ti2AlNb alloy electron beam welding according to claim 1, characterized in that, The welding surface of the pretreated forge piece comprises a rectangular ring, and the outer diameter size is 200-300mm; And / or, the pretreated forge piece further undergoes rough machining before the electron beam welding, and the rough machining comprises: thinning the wall thickness of the to-be-welded part of the pretreated forge piece to 5-8mm.

7. The heat treatment method suitable for Ti2AlNb alloy electron beam welding according to claim 1, characterized in that, The acceleration voltage of the electron beam welding is 130-160kv, the electron beam current is 7-12mA, and the welding speed is 10-15m / s.

8. The heat treatment method suitable for Ti2AlNb alloy electron beam welding according to claim 1, characterized in that, In step (b), the gas pressure of the gas quenching is 0.7-1bar.

9. The heat treatment method suitable for Ti2AlNb alloy electron beam welding according to claim 1, characterized in that, The temperature of the aging treatment is 800-870℃, and the time of the aging treatment is 8-16h.

10. The heat treatment method suitable for electron beam welding of a Ti2AlNb alloy according to claim 1, wherein in step (c), the gas pressure of the gas quenching is 0.7-1bar.

11. The heat treatment method suitable for Ti2AlNb alloy electron beam welding according to claim 1, characterized in that, The microstructure of the Ti2AlNb alloy welded piece comprises B2 phase, O phase and α2 phase, the volume fraction of the B2 phase is 5%-30%, the O phase and the α2 phase comprise large platelets and small platelets, the length of the large platelets is 1-5μm, the total volume fraction of the O phase and the α2 phase of the large platelets is 10%-35%, the length of the small platelets is less than 1μm, and the total volume fraction of the O phase and the α2 phase of the small platelets is 35%-60%.

12. The heat treatment method suitable for Ti2AlNb alloy electron beam welding according to claim 1, characterized in that, The tensile strength of the Ti2AlNb alloy welded piece at 25℃ is 1020-1100MPa, the yield strength is 960-1050MPa, the elongation is 6%-10%, and the reduction of area is 8%-15%.

13. The heat treatment method suitable for Ti2AlNb alloy electron beam welding according to claim 1, characterized in that, The Ti2AlNb alloy welding piece has a tensile strength of 840-900 MPa, a yield strength of 700-800 MPa, an elongation of 11%-25%, and a reduction of area of 26%-80% at 650 DEG C.

Images