Heat treatment method of double-phase titanium alloy, double-phase titanium alloy and titanium alloy product

Abstract

The invention relates to a heat treatment method of a double-phase titanium alloy, the double-phase titanium alloy and a titanium alloy product. The heat treatment method of the double-phase titanium alloy comprises the following steps that a double-phase titanium alloy workpiece is subjected to first annealing treatment, so that the core temperature of the double-phase titanium alloy workpiece reaches 20-60 DEG C below the beta-phase transformation temperature; the double-phase titanium alloy workpiece subjected to first annealing treatment is cooled to 70-250 DEG C below the beta-phase transformation temperature along with the furnace at the cooling speed of 1-5 DEG C / min; and the cooled biphase titanium alloy workpiece is subjected to second annealing treatment. According to the heat treatment method for the double-phase titanium alloy, all the steps interact, the double-state structure uniformity of the double-phase titanium alloy can be effectively improved, and then the comprehensive performance such as the strength, plasticity and toughness of the double-phase titanium alloy is improved.

Description

Technical Field

[0001] The present application relates to the field of alloys, and in particular to a heat treatment method for a duplex titanium alloy, a duplex titanium alloy and a titanium alloy product. Background Art

[0002] Dual-phase titanium alloy refers to a titanium alloy with both α phase and β phase in the microstructure. The α phase has a close-packed hexagonal crystal structure, which gives the alloy high strength and thermal stability; the β phase has a body-centered cubic crystal structure, which gives the alloy good plasticity and toughness. Dual-phase titanium alloys are widely used in aerospace, medical equipment, automotive industry and other fields.

[0003] Under traditional heat treatment methods, duplex titanium alloys are prone to problems with uneven dual-state structures. This structural inhomogeneity is more prominent in large or complex-shaped duplex titanium alloy workpieces. Existing heat treatment processes often make it difficult to simultaneously achieve high strength and good plasticity and toughness for duplex titanium alloys. Generally speaking, increasing strength may lead to decreased plasticity and toughness, and vice versa. For example, after some simple annealing treatments, although the plasticity of the alloy is improved, the strength does not meet the requirements of certain high-end applications.

[0004] Therefore, the traditional technology still needs to be improved. Summary of the invention

[0005] Based on this, the present application provides a heat treatment method for a dual-phase titanium alloy, a dual-phase titanium alloy and a titanium alloy product. The heat treatment method can effectively improve the uniformity of the dual-state structure of the dual-phase titanium alloy, thereby improving the comprehensive properties of the dual-phase titanium alloy such as strength, plasticity and toughness.

[0006] The technical solution of this application to solve the above technical problems is as follows.

[0007] The first aspect of the present application provides a method for preparing a dual-phase titanium alloy, comprising the following steps:

[0008] Performing a first annealing treatment on the dual-phase titanium alloy workpiece so that the core temperature of the dual-phase titanium alloy workpiece reaches 20° C. to 60° C. below the β-phase transformation temperature;

[0009] Cooling the dual-phase titanium alloy workpiece after the first annealing treatment to 70°C to 250°C below the β phase transformation temperature at a cooling rate of 1°C / min to 5°C / min in a furnace;

[0010] The cooled duplex titanium alloy workpiece is subjected to a second annealing treatment.

[0011] The heat treatment method of the dual-phase titanium alloy of the present application is to perform a first annealing treatment on the dual-phase titanium alloy workpiece so that the core temperature of the dual-phase titanium alloy workpiece reaches 20°C~60°C below the β-phase transformation temperature. During the specific first annealing treatment process, the α-phase and β-phase in the alloy can undergo reasonable phase transformation and element diffusion, laying a foundation for forming an ideal dual-state structure; then the dual-phase titanium alloy workpiece after the first annealing treatment is furnace cooled at a cooling rate of 1°C / min~5°C / min to 70°C~250°C below the β-phase transformation temperature. A specific cooling method and rate are used in the cooling stage to control the morphology, size and distribution of the primary α-phase and the transformed β-structure, thereby improving the uniformity of the structure and optimizing the mechanical properties; finally, the cooled dual-phase titanium alloy workpiece is subjected to a second annealing treatment to promote the precipitation of fine needle-shaped α-phase and strengthen the microstructure of the alloy. The interaction of each step can effectively improve the uniformity of the dual-state structure of the dual-phase titanium alloy, thereby improving the comprehensive properties of the dual-phase titanium alloy such as strength, plasticity and toughness.

[0012] In one embodiment, the dual-phase titanium alloy workpiece after the first annealing treatment is furnace cooled at a cooling rate of 1°C / min to 5°C / min to 70°C to 200°C below the β-phase transformation temperature.

[0013] In one embodiment, the dual-phase titanium alloy workpiece after the first annealing treatment is furnace cooled at a cooling rate of 2°C / min-5°C / min to 70°C-200°C below the β-phase transformation temperature.

[0014] In one embodiment, the furnace cooling time is 60 min to 240 min.

[0015] In one embodiment, the first annealing process comprises the following steps:

[0016] The dual-phase titanium alloy workpiece is kept at 20° C. to 60° C. below the β phase transformation temperature for 60 min to 120 min.

[0017] In one embodiment, the temperature of the second annealing treatment is 500° C. to 600° C.;

[0018] And / or, the second annealing treatment time is 240min~360min.

[0019] In one embodiment, after the furnace cooling and before the second annealing treatment, the step of air cooling or wind cooling the duplex titanium alloy workpiece to room temperature is also included.

[0020] In one embodiment, the dual-phase titanium alloy includes one of TC4 titanium alloy, TC4ELI titanium alloy, TC16 titanium alloy and TC19 titanium alloy.

[0021] In a second aspect of the present application, a dual-phase titanium alloy is provided, which is produced by the heat treatment method of the dual-phase titanium alloy as described above.

[0022] The third aspect of the present application also provides a titanium alloy product, comprising the dual-phase titanium alloy as described above. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 The microstructure diagram of the dual-phase titanium alloy workpiece to be processed in Examples 1-4 and Comparative Examples 1 and 2;

[0024] Figure 2 The microstructure diagrams of the dual-phase titanium alloy workpieces to be processed in Examples 5-8 and Comparative Examples 3 and 4;

[0025] Figure 3 The microstructure diagram of the dual-phase titanium alloy workpiece to be processed in Examples 9-12 and Comparative Example 5;

[0026] Figure 4 The microstructure diagram of the dual-phase titanium alloy workpiece to be processed in Examples 13-16 and Comparative Example 6;

[0027] Figure 5 is a microstructure diagram of the dual-phase titanium alloy prepared in Example 1;

[0028] Figure 6 is a microstructure diagram of the dual-phase titanium alloy prepared in Example 2;

[0029] Figure 7 is a microstructure diagram of the dual-phase titanium alloy prepared in Example 3;

[0030] Figure 8 is a microstructure diagram of the dual-phase titanium alloy prepared in Example 4;

[0031] Fig. 9 is a microstructure diagram of the dual-phase titanium alloy prepared in Example 5;

[0032] Fig.10 is a microstructure diagram of the dual-phase titanium alloy prepared in Example 6;

[0033] Fig.11 is a microstructure diagram of the dual-phase titanium alloy prepared in Example 7;

[0034] Fig.12 is a microstructure diagram of the dual-phase titanium alloy prepared in Example 8;

[0035] Fig.13 is a microstructure diagram of the dual-phase titanium alloy prepared in Example 9;

[0036] Fig.14is a microstructure diagram of the dual-phase titanium alloy prepared in Example 10;

[0037] Fig.15 is a microstructure diagram of the dual-phase titanium alloy prepared in Example 11;

[0038] Fig.16 is a microstructure diagram of the dual-phase titanium alloy prepared in Example 12;

[0039] Fig.17 is a microstructure diagram of the dual-phase titanium alloy prepared in Example 13;

[0040] Fig.18 is a microstructure diagram of the dual-phase titanium alloy prepared in Example 14;

[0041] Fig.19 is a microstructure diagram of the dual-phase titanium alloy prepared in Example 15;

[0042] Fig. 20 is a microstructure diagram of the dual-phase titanium alloy prepared in Example 16;

[0043] Fig.21 is a microstructure diagram of the dual-phase titanium alloy prepared in Comparative Example 1;

[0044] Fig. 22 is a microstructure diagram of the dual-phase titanium alloy prepared in Comparative Example 2;

[0045] Fig.23 is a microstructure diagram of the dual-phase titanium alloy prepared in Comparative Example 3;

[0046] Fig.24 is a microstructure diagram of the dual-phase titanium alloy prepared in Comparative Example 4;

[0047] Fig.25 is a microstructure diagram of the dual-phase titanium alloy prepared in Comparative Example 5;

[0048] Fig.26 This is the microstructure diagram of the dual-phase titanium alloy prepared in Comparative Example 6. DETAILED DESCRIPTION

[0049] References to embodiments of the present invention will now be provided in detail, one or more examples of which are described below. Each example is provided as an explanation rather than a limitation of the present invention. In fact, it will be apparent to those skilled in the art that various modifications and variations may be made to the present invention without departing from the scope or spirit of the present invention. For example, a feature illustrated or described as part of one embodiment may be used in another embodiment to produce a further embodiment.

[0050] Therefore, it is intended that the present invention covers such modifications and variations that fall within the scope of the appended claims and their equivalents. Other objects, features and aspects of the present invention are disclosed in or are obvious from the following detailed description. Those of ordinary skill in the art will appreciate that this discussion is only a description of exemplary embodiments and is not intended to limit the broader aspects of the present invention.

[0051] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art of the present invention. The terms used in the specification of the present invention herein are only for the purpose of describing specific embodiments and are not intended to limit the present invention.

[0052] The term "comprises", "comprising" or any other variant thereof is intended to cover non-exclusive inclusion, so that the process, method, article or equipment including a series of elements includes not only those elements, but also includes other elements not explicitly listed, or also includes elements inherent to such process, method, article or equipment. In the absence of more restrictions, the elements defined by the sentence "comprising one..." do not exclude the presence of other identical elements in the process, method, article or equipment including the elements. The indefinite articles "a kind of" and "an" before the elements or components of the present invention are not restrictive to the quantity requirements (i.e., the number of occurrences) of the elements or components. Therefore, "a" or "a kind of" should be interpreted as including one or at least one, and the elements or components in the singular form also include the plural form, unless the number clearly refers only to the singular form. The meaning of "multiple" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0053] The weight of the relevant components mentioned in the description of the embodiments of the present invention may not only refer to the specific content of each component, but also indicate the weight ratio between the components. Therefore, as long as the content of the relevant components is proportionally enlarged or reduced according to the description of the embodiments of the present invention, it is within the scope disclosed in the description of the embodiments of the present invention. Specifically, the weight described in the description of the embodiments of the present invention may be a mass unit known in the chemical industry such as μg, mg, g, kg, etc.

[0054] Except as shown in the operating examples or otherwise indicated, all numbers used in the specification and claims to indicate the amount of ingredients, physicochemical properties, etc. are understood to be adjusted by the term "about" in all cases. For example, therefore, unless otherwise indicated, the numerical parameters listed in the above specification and the attached claims are approximate values, and those skilled in the art can use the teachings disclosed herein to seek to obtain the desired properties and appropriately change these approximate values. The use of numerical ranges expressed as endpoints includes all numbers within the range and any range within the range, for example, 1 to 5 includes 1, 1.1, 1.3, 1.5, 2, 2.75, 3, 3.80, 4 and 5, etc.

[0055] As shown in the background technology, the strength of the dual-state structure of the dual-phase titanium alloy is limited by the ratio and size of the primary spherical α and the secondary needle-shaped α. Reasonable regulation of the ratio and size of the two forms of α phase through heat treatment is an important method to improve the strength of the dual-state structure of the α+β dual-phase titanium alloy. In traditional technology, the strength of the alloy is increased by high-temperature solid solution water cooling + low-temperature aging, but this method is difficult to implement in actual industrial production; and water cooling may cause deformation of the plate, so it is not suitable for the production of large-sized plates in industry. If the high-temperature solid solution air cooling + aging process is directly adopted, the size of the needle-shaped / lamellar α phase will often be too large in industrial production, which ultimately leads to no significant improvement in the structure and performance after heat treatment compared with before heat treatment.

[0056] Based on this, an embodiment of the present application provides a heat treatment method for a dual-phase titanium alloy, comprising steps S10 to S30.

[0057] Step S10: performing a first annealing treatment on the dual-phase titanium alloy workpiece so that the core temperature of the dual-phase titanium alloy workpiece reaches 20° C. to 60° C. below the β-phase transformation temperature.

[0058] It can be understood that the core temperature of the above-mentioned dual-phase titanium alloy workpiece is 20°C to 60°C below the β phase transformation temperature, and the value includes the minimum and maximum values ​​of the range, and each value between the minimum and maximum values. Specific examples include but are not limited to the point values ​​in the embodiment and the following point values: T β -20℃、T β -21℃、T β -22℃、T β -23℃、T β -24℃、T β -25℃、T β -26℃、T β -27℃、T β -28℃、T β -29℃、T β -30℃、T β -31℃、Tβ -32℃、T β -33℃、T β -34℃、T β -35℃、T β -36℃、T β -37℃、T β -38℃、T β -39℃、T β -40℃、T β -41℃、T β -42℃、T β -43℃、T β -44℃、T β -45℃、T β -46℃、T β -47℃、T β -48℃、T β -49℃、T β -50℃、T β -51℃、T β -52℃、T β -53℃、T β -54℃、T β -55℃、T β -56℃、T β -57℃、T β -58℃、T β -59℃ or T β -60°C, or any range consisting of two of these values, including, for example: T β -20℃~T β -50℃, T β is the phase transition temperature of the duplex titanium alloy workpiece.

[0059] In some embodiments, the first annealing treatment comprises the following steps: keeping the dual-phase titanium alloy workpiece at 20° C. to 60° C. below the β-phase transformation temperature for 60 min to 120 min.

[0060] The above-mentioned insulation time is 60min~120min, and the values ​​include the minimum and maximum values ​​of the range, and every value between the minimum and maximum values. Specific examples include but are not limited to the point values ​​in the embodiments and the following point values: 60min, 65min, 70min, 75min, 80min, 85min, 90min, 95min, 100min, 105min, 110min, 115min or 120min, or a range composed of any two of these values, as an example, including: 60min~100min.

[0061] By controlling the above-mentioned holding time and temperature, the ratio and morphology of the α phase and the β phase can be adjusted, thereby optimizing the properties of the alloy.

[0062] Step S20: Cooling the dual-phase titanium alloy workpiece after the first annealing treatment to a temperature of 70°C to 250°C below the β-phase transformation temperature at a cooling rate of 1°C / min to 5°C / min.

[0063] It is understandable that if the cooling rate is too fast, on the one hand, the furnace cooling rate is difficult to control and cannot be achieved for the equipment; on the other hand, if the furnace cooling rate is too fast, it is not conducive to the formation of spherical α phase, and the metastable state is prone to form lamellar α phase, which is not conducive to improving the strength of the material; if the cooling rate is too slow, on the one hand, the cooling process time is too long, which will lead to too high energy consumption, and on the other hand, the main phenomenon that occurs after the cooling rate is too slow is the slow growth of the original spherical phase, and no new small spherical α phase will be formed, which is not conducive to improving the comprehensive performance of the alloy.

[0064] The above cooling rate is 1°C / min~5°C / min, and the values ​​include the minimum and maximum values ​​in the range, and every value between the minimum and maximum values. Specific examples include but are not limited to the point values ​​in the embodiments and the following point values: 1°C / min, 2°C / min, 3°C / min, 4°C / min, 5°C / min.

[0065] The above-mentioned furnace cooling temperature is 70°C to 250°C below the β phase transformation temperature, and the value includes the minimum and maximum values ​​of the range, and each value between the minimum and maximum values. Specific examples include but are not limited to the point values ​​in the embodiment and the following point values: T β -70℃、T β -71℃、T β -72℃、T β -73℃、T β -74℃、T β -75℃、T β -76℃、T β -77℃、T β -78℃、T β -79℃、T β -80℃、T β -81℃、T β -82℃、T β -83℃、T β -84℃、T β -85℃、T β -86℃、T β -87℃、T β -88℃、T β -89℃、T β -90℃、T β -91℃、T β-92℃、T β -93℃、T β -94℃、T β -95℃、T β -96℃、T β -97℃、T β -98℃、T β -99℃、T β -100℃、T β -105℃、T β -110℃、T β -115℃、T β -120℃、T β -125℃、T β -130℃、T β -135℃、T β -140℃、T β -145℃、T β -150℃、T β -155℃、T β -160℃、T β -165℃、T β -170℃、T β -175℃、T β -180℃、T β -185℃、T β -190℃、T β -195℃、T β -200℃、T β -205℃、T β -210℃、T β -215℃、T β -220℃、T β -225℃、T β -230℃、T β -235℃、T β -240℃、T β -245℃ or T β -250°C, or any range consisting of two of these values, including, for example: T β -70℃~T β -230℃.

[0066] In some embodiments, the dual-phase titanium alloy workpiece after the first annealing treatment is furnace cooled at a cooling rate of 1°C / min to 5°C / min to a temperature of 70°C to 200°C below the β-phase transformation temperature.

[0067] In some embodiments, the dual-phase titanium alloy workpiece after the first annealing treatment is furnace cooled at a cooling rate of 2°C / min-5°C / min to 70°C-200°C below the β-phase transformation temperature.

[0068] In some embodiments, the furnace cooling time is 60 min to 240 min.

[0069] The above-mentioned furnace cooling time is 60min~240min, and the values ​​include the minimum and maximum values ​​of the range, and each value between the minimum and maximum values. Specific examples include but are not limited to the point values ​​in the embodiment and the following point values: 60min, 65min, 70min, 75min, 80min, 85min, 90min, 95min, 100min, 105min, 110min, 115min, 120min, 125min, 130min, 135min, 140min, 145min, 150min, 155min, 160min, 165min, 170min, 175min, 180min, 185min, 190min, 195min, 200min, 205min, 210min, 215min, 220min, 225min, 230min, 235min, 240min, or a range consisting of any two of these values, as an example, includes: 100min~240min.

[0070] It can be understood that by controlling the slow cooling in the furnace after the first annealing, a part of the α phase can be induced to form and grow during the slow cooling process, followed by immediate air cooling or wind cooling, which can retain part of the metastable phase and improve the strength during the second annealing process. Through this method, the strength of the dual-state structure can be increased by 100-150MPa while retaining its high impact toughness.

[0071] Step S30: performing a second annealing treatment on the cooled duplex titanium alloy workpiece.

[0072] It can be understood that the above-mentioned heat treatment process induces the growth of fine spherical α phase in the dual-state structure during the cooling process, so that the proportion of spherical α phase in the dual-state structure increases, and it is more inclined to equiaxed structure, thereby improving its comprehensive performance, which is beneficial to solving the problem of insufficient proportion of spherical phase in the dual-state structure.

[0073] In some embodiments, the temperature of the second annealing treatment is 500° C.-600° C.

[0074] The temperature of the second annealing treatment is 500°C~600°C, and the values ​​include the minimum and maximum values ​​of the range, and every value between the minimum and maximum values. Specific examples include but are not limited to the point values ​​in the embodiment and the following point values: 500°C, 505°C, 510°C, 515°C, 520°C, 525°C, 530°C, 535°C, 540°C, 545°C, 550°C, 555°C, 560°C, 565°C, 570°C, 575°C, 580°C, 585°C, 590°C, 595°C or 600°C, or a range composed of any two of these values, as an example, including: 500°C~550°C.

[0075] In some embodiments, the second annealing treatment time is 240 min to 360 min.

[0076] The time of the second annealing treatment is 240min~360min, and the values ​​include the minimum and maximum values ​​of the range, and each value between the minimum and maximum values. Specific examples include but are not limited to the point values ​​in the embodiment and the following point values: 240min, 245min, 250min, 255min, 260min, 265min, 270min, 275min, 280min, 285min, 290min, 295min, 300min, 305min, 310min, 315min, 320min, 325min, 330min, 335min, 340min, 345min, 350min or 360min, or a range composed of any two of these values, as an example, including: 240min~300min.

[0077] It can be understood that during the second annealing process, the β phase in the alloy further undergoes phase transformation to precipitate fine α phase, thereby improving the strength and hardness of the alloy. At the same time, the second annealing treatment can also improve the toughness and fatigue resistance of the alloy.

[0078] In some of the embodiments, after the furnace cooling and before the second annealing treatment, the step of air cooling or wind cooling the duplex titanium alloy workpiece to room temperature is also included.

[0079] It is understandable that the reason why air cooling is required after the above-mentioned first annealing treatment (i.e., not completely furnace cooling to room temperature at this rate) is: on the one hand, furnace cooling to a higher temperature retains the residual β phase in the matrix, allowing it to continue to precipitate fine needle-shaped α phase in subsequent heat treatment, thereby improving its strength; on the other hand, complete furnace cooling to room temperature will form an equiaxed structure, and the material will have better plasticity and toughness, but lower strength.

[0080] In some embodiments, the above-mentioned dual-phase titanium alloy includes one of TC4 titanium alloy, TC4ELI titanium alloy, TC16 titanium alloy and TC19 titanium alloy.

[0081] The heat treatment method of the above-mentioned dual-phase titanium alloy of the present application is to perform a first annealing treatment on the dual-phase titanium alloy workpiece so that the core temperature of the dual-phase titanium alloy workpiece reaches 20°C~60°C below the β-phase transformation temperature. During the specific first annealing treatment process, the α-phase and β-phase in the alloy can undergo reasonable phase transformation and element diffusion, laying the foundation for the formation of an ideal dual-state structure; then the dual-phase titanium alloy workpiece after the first annealing treatment is furnace cooled at a cooling rate of 1°C / min~5°C / min to 70°C~250°C below the β-phase transformation temperature. A specific cooling method and rate are used in the cooling stage to control the morphology, size and distribution of the primary α-phase and the transformed β-structure, thereby improving the uniformity of the structure and optimizing the mechanical properties; finally, the cooled dual-phase titanium alloy workpiece is subjected to a second annealing treatment to promote the precipitation of fine needle-shaped α-phase and strengthen the microstructure of the alloy. The interaction of each step can effectively improve the uniformity of the dual-state structure of the dual-phase titanium alloy, thereby improving the comprehensive properties of the dual-phase titanium alloy such as strength, plasticity and toughness.

[0082] An embodiment of the present application further provides a dual-phase titanium alloy, which is prepared by the above-mentioned heat treatment method of the dual-phase titanium alloy.

[0083] The above-mentioned dual-phase titanium alloy has excellent comprehensive properties such as organizational uniformity, strength, plasticity and toughness.

[0084] An embodiment of the present application also provides a titanium alloy product, including the above-mentioned dual-phase titanium alloy.

[0085] The titanium alloy products of the present application include the dual-phase titanium alloy provided by the present application, and thus have at least the same advantages as the above-mentioned dual-phase titanium alloy. In some examples, the titanium alloy products include but are not limited to aviation equipment, aerospace equipment, ship equipment, chemical equipment, biomedical equipment, and automotive industry equipment.

[0086] In order to make the purpose, technical solutions and advantages of the present application more concise and clear, the present application is described with the following specific embodiments, but the present application is by no means limited to these embodiments. The embodiments described below are only preferred embodiments of the present application and can be used to describe the present application, and cannot be understood as limiting the scope of the present application. It should be pointed out that any modifications, equivalent substitutions and improvements made within the spirit and principles of the present application should be included in the protection scope of the present application.

[0087] The present application is further described in detail below in conjunction with specific implementation methods, but the implementation methods of the present application are not limited thereto.

[0088] Example 1

[0089] (1) A TC4 dual-phase titanium alloy workpiece (β phase transformation point is 983°C) to be processed is subjected to a first annealing treatment so that the core temperature of the dual-phase titanium alloy workpiece reaches 53°C below the β phase transformation temperature.

[0090] (2) The duplex titanium alloy workpiece after the first annealing treatment is cooled in a furnace at a cooling rate of 1°C per minute to 83°C below the β-phase transformation temperature, and then taken out of the furnace and air-cooled to room temperature.

[0091] (3) The cooled duplex titanium alloy workpiece is subjected to a second annealing treatment at a temperature of 500° C. and a time of 240 min to obtain a duplex titanium alloy.

[0092] Example 2

[0093] Example 2 is basically the same as Example 1, except that the temperature of the cooling treatment in step (2) is different, specifically, the temperature is cooled at a cooling rate of 1°C per minute to 133°C below the β phase transition temperature.

[0094] Other conditions and parameters are the same as those in Example 1. Please see Table 4 for specific test results.

[0095] Example 3

[0096] Example 3 is basically the same as Example 1, except that the temperature of the cooling treatment in step (2) is different, specifically, the temperature is cooled at a cooling rate of 1°C per minute to 183°C below the β phase transition temperature.

[0097] Other conditions and parameters are the same as those in Example 1. Please see Table 4 for specific test results.

[0098] Example 4

[0099] Example 4 is basically the same as Example 1, except that the temperature of the cooling treatment in step (2) is different, specifically, the temperature is cooled at a cooling rate of 1°C per minute to 233°C below the β phase transition temperature.

[0100] Other conditions and parameters are the same as those in Example 1. Please see Table 4 for specific test results.

[0101] Example 5

[0102] (1) A duplex titanium alloy workpiece (β phase transformation point is 987°C) to be processed is subjected to a first annealing treatment so that the core temperature of the duplex titanium alloy workpiece reaches 52°C below the β phase transformation temperature.

[0103] (2) The duplex titanium alloy workpiece after the first annealing treatment is cooled in a furnace at a cooling rate of 1°C per minute to 87°C below the β-phase transformation temperature, and then taken out of the furnace and air-cooled to room temperature.

[0104] (3) The cooled duplex titanium alloy workpiece is subjected to a second annealing treatment at a temperature of 600° C. and a time of 240 min to obtain a duplex titanium alloy.

[0105] Example 6

[0106] Example 6 is basically the same as Example 5, except that the temperature of the cooling treatment in step (2) is different, specifically, the temperature is cooled at a cooling rate of 1°C per minute to 137°C below the β phase transition temperature.

[0107] Other conditions and parameters are the same as those in Example 5. Please see Table 4 for specific test results.

[0108] Example 7

[0109] Example 7 is basically the same as Example 5, except that the temperature of the cooling treatment in step (2) is different, specifically, the temperature is cooled at a cooling rate of 1°C per minute to 187°C below the β phase transition temperature.

[0110] Other conditions and parameters are the same as those in Example 5. Please see Table 4 for specific test results.

[0111] Example 8

[0112] Example 8 is basically the same as Example 5, except that the temperature of the cooling treatment in step (2) is different, specifically, the temperature is cooled at a cooling rate of 1°C per minute to 237°C below the β phase transition temperature.

[0113] Other conditions and parameters are the same as those in Example 5. Please see Table 4 for specific test results.

[0114] Example 9

[0115] (1) A duplex titanium alloy workpiece (β phase transformation point is 982°C) to be processed is subjected to a first annealing treatment so that the core temperature of the duplex titanium alloy workpiece reaches 52°C below the β phase transformation temperature.

[0116] (2) The duplex titanium alloy workpiece after the first annealing treatment is cooled in a furnace at a cooling rate of 2° C. per minute to 82° C. below the β-phase transformation temperature, and then taken out of the furnace and air-cooled.

[0117] (3) The cooled duplex titanium alloy workpiece is subjected to a second annealing treatment at a temperature of 500° C. and a time of 240 min to obtain a duplex titanium alloy.

[0118] Example 10

[0119] Example 10 is basically the same as Example 9, except that the temperature of the cooling treatment in step (2) is different, specifically, the temperature is cooled at a cooling rate of 2°C per minute to 132°C below the β phase transition temperature.

[0120] Other conditions and parameters are the same as those in Example 9. Please see Table 4 for specific test results.

[0121] Embodiment 11

[0122] Example 11 is basically the same as Example 9, except that the temperature of the cooling treatment in step (2) is different, specifically, the temperature is cooled at a cooling rate of 2°C per minute to 182°C below the β phase transition temperature.

[0123] Other conditions and parameters are the same as those in Example 9. Please see Table 4 for specific test results.

[0124] Example 12

[0125] Example 12 is basically the same as Example 9, except that the temperature of the cooling treatment in step (2) is different, specifically, the temperature is cooled at a cooling rate of 2°C per minute to 232°C below the β phase transition temperature.

[0126] Other conditions and parameters are the same as those in Example 9. Please see Table 4 for specific test results.

[0127] Embodiment 13

[0128] (1) A duplex titanium alloy workpiece (β phase transformation point is 987°C) to be processed is subjected to a first annealing treatment so that the core temperature of the duplex titanium alloy workpiece reaches 54°C below the β phase transformation temperature.

[0129] (2) The duplex titanium alloy workpiece after the first annealing treatment is cooled in a furnace at a cooling rate of 2° C. per minute to 87° C. below the β-phase transformation temperature, and then taken out of the furnace and air-cooled.

[0130] (3) The cooled duplex titanium alloy workpiece is subjected to a second annealing treatment at a temperature of 600° C. and a time of 240 min to obtain a duplex titanium alloy.

[0131] Embodiment 14

[0132] Example 14 is basically the same as Example 13, except that the cooling temperature in step (2) is different, specifically, the temperature is cooled at a cooling rate of 5°C per minute to 137°C below the β phase transition temperature.

[0133] Other conditions and parameters are the same as those in Example 13. Please see Table 4 for specific test results.

[0134] Embodiment 15

[0135] Example 15 is basically the same as Example 13, except that the cooling temperature in step (2) is different, specifically, the temperature is cooled at a cooling rate of 5°C per minute to 187°C below the β phase transition temperature.

[0136] Other conditions and parameters are the same as those in Example 13. Please see Table 4 for specific test results.

[0137] Example 16

[0138] Example 16 is basically the same as Example 13, except that the cooling temperature in step (2) is different, specifically, the temperature is cooled at a cooling rate of 5°C per minute to 237°C below the β phase transition temperature.

[0139] Other conditions and parameters are the same as those in Example 13. Please see Table 4 for specific test results.

[0140] Comparative Example 1

[0141] Comparative Example 1 is substantially the same as Example 1, except that air cooling is performed directly after the first annealing treatment.

[0142] (1) A duplex titanium alloy workpiece (β phase transformation point is 983° C.) is subjected to a first annealing treatment so that the core temperature of the duplex titanium alloy workpiece reaches 53° C. below the β phase transformation temperature.

[0143] (2) Air-cooling the duplex titanium alloy workpiece after the first annealing treatment to room temperature.

[0144] (3) The cooled duplex titanium alloy workpiece is subjected to a second annealing treatment at a temperature of 500° C. and a time of 240 min to obtain a duplex titanium alloy.

[0145] Comparative Example 2

[0146] Comparative Example 2 is substantially the same as Example 1, except that the temperature of the cooling treatment in step (2) is different.

[0147] (1) A duplex titanium alloy workpiece (β phase transformation point is 983° C.) is subjected to a first annealing treatment so that the core temperature of the duplex titanium alloy workpiece reaches 53° C. below the β phase transformation temperature.

[0148] (2) The duplex titanium alloy workpiece after the first annealing treatment is cooled in a furnace at a cooling rate of 1°C per minute to 283°C below the β-phase transformation temperature, and then taken out of the furnace and air-cooled to room temperature.

[0149] (3) The cooled duplex titanium alloy workpiece is subjected to a second annealing treatment at a temperature of 500° C. and a time of 240 min to obtain a duplex titanium alloy.

[0150] Comparative Example 3

[0151] Comparative Example 3 is substantially the same as Example 5, except that the temperature of the cooling treatment in step (2) is different, specifically, the temperature is cooled at a cooling rate of 1°C per minute to 57°C below the β phase transition temperature.

[0152] Other conditions and parameters are the same as those in Example 5. Please see Table 5 for specific test results.

[0153] Comparative Example 4

[0154] Comparative Example 4 is substantially the same as Example 5, except that the temperature of the cooling treatment in step (2) is different, specifically, the temperature is cooled at a cooling rate of 1°C per minute to 287°C below the β phase transition temperature.

[0155] Other conditions and parameters are the same as those in Example 5. Please see Table 5 for specific test results.

[0156] Comparative Example 5

[0157] Comparative Example 5 is substantially the same as Example 9, except that the temperature of the cooling treatment in step (2) is different, specifically, the temperature is cooled at a cooling rate of 2°C per minute to 282°C below the β phase transition temperature.

[0158] Other conditions and parameters are the same as those in Example 9. Please see Table 5 for specific test results.

[0159] Comparative Example 6

[0160] Comparative Example 6 is substantially the same as Example 13, except that the cooling temperature in step (2) is different, specifically, the temperature is lowered to 287° C. below the β-phase transition temperature at a cooling rate of 5° C. per minute.

[0161] Other conditions and parameters are the same as those in Example 13. Please see Table 5 for specific test results.

[0162] test:

[0163] 1. Observation of the microstructure of the duplex titanium alloys prepared in the examples and comparative examples: The test was carried out in accordance with the national standard "GB / T 5168-2020 Titanium and Titanium Alloy High and Low Magnification Microstructure Test Method"

[0164] 2. The yield strength of the duplex titanium alloys prepared in the examples and comparative examples was tested in accordance with the national standard "GB / T228.1 2016-2021 Tensile test of metallic materials Part 1: Room temperature test method"

[0165] 3. The tensile strength of the duplex titanium alloys prepared in the examples and comparative examples was tested in accordance with the national standard "GB / T228.1 2016-2021 Tensile test of metallic materials Part 1: Room temperature test method"

[0166] 4. The impact toughness of the dual-phase titanium alloys prepared in the examples and comparative examples was tested in accordance with the national standard "GB / T229 Charpy pendulum impact test method for metallic materials".

[0167] Table 1

[0168]

[0169] Table 2

[0170]

[0171] Table 3

[0172]

[0173] Table 4

[0174]

[0175] Table 5

[0176]

[0177] Among them, Table 1 is the process parameter conditions of Examples 1 to 16, Table 2 is the process parameter conditions in Comparative Examples 1 to 6, Table 3 is the properties of the dual-phase titanium alloys of Examples 1 to 16 and Comparative Examples 1 to 6 before heat treatment, Table 4 is the properties of the dual-phase titanium alloys prepared in Examples 1 to 16, and Table 5 is the properties of the dual-phase titanium alloys prepared in Comparative Examples 1 to 6. Figure 1 The microstructure diagram of the dual-phase titanium alloy workpiece to be processed in Examples 1-4 and Comparative Examples 1 and 2; Figure 2 The microstructure diagrams of the dual-phase titanium alloy workpieces to be processed in Examples 5-8 and Comparative Examples 3 and 4; Figure 3 The microstructure diagrams of the dual-phase titanium alloy workpieces to be processed in Examples 9-12 and Comparative Example 5; Figure 4 The microstructure diagram of the dual-phase titanium alloy workpiece to be processed in Examples 13-16 and Comparative Example 6; Figure 5~Figure 20 They are microstructure diagrams of the dual-phase titanium alloys prepared in Examples 1 to 16 respectively; Figure 21~Figure 26 They are respectively the microstructure diagrams of the dual-phase titanium alloys prepared in Comparative Examples 1 to 6; it can be seen from the above figure that through the above-mentioned heat treatment process, small spherical α phases grow, which increases the proportion of spherical α phases in the dual-state structure, and is more inclined to an equiaxed structure, forming spherical phases and needle-shaped α phases of different sizes, forming a polymorphic microstructure, thereby improving its comprehensive mechanical properties.

[0178] It can be seen from Tables 3 to 5 that, compared with Comparative Examples 1 to 6, the dual-phase titanium alloys prepared in Examples 1 to 16 have better dual-state microstructure uniformity and higher comprehensive mechanical properties of strength, plasticity and toughness.

[0179] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0180] The above-described embodiments only express several implementation methods of the present application, which is convenient for understanding the technical solution of the present application in detail, but it cannot be understood as limiting the scope of protection of the invention patent. It should be pointed out that for ordinary technicians in this field, without departing from the concept of the present application, several modifications and improvements can be made, which all belong to the scope of protection of the present application. It should be understood that the technical solutions obtained by those skilled in the art through logical analysis, reasoning or limited experiments on the basis of the technical solutions provided in the present application are all within the scope of protection of the claims attached to the present application. Therefore, the scope of protection of the patent of this application shall be based on the contents of the attached claims, and the description and drawings can be used to explain the contents of the claims.

Claims

1. A heat treatment method for a dual-phase titanium alloy, characterized in that: The following steps are involved: Performing a first annealing treatment on the dual-phase titanium alloy workpiece so that the core temperature of the dual-phase titanium alloy workpiece reaches 20° C. to 60° C. below the β-phase transformation temperature; Cooling the dual-phase titanium alloy workpiece after the first annealing treatment to 70°C to 250°C below the β phase transformation temperature at a cooling rate of 1°C / min to 5°C / min in a furnace; The cooled duplex titanium alloy workpiece is subjected to a second annealing treatment.

2. The heat treatment method of the dual-phase titanium alloy according to claim 1, characterized in that: The dual-phase titanium alloy workpiece after the first annealing treatment is furnace cooled at a cooling rate of 1°C / min to 5°C / min to 70°C to 200°C below the β phase transformation temperature.

3. The heat treatment method of the dual-phase titanium alloy according to claim 2, characterized in that: The dual-phase titanium alloy workpiece after the first annealing treatment is furnace cooled to 70°C to 200°C below the β phase transformation temperature at a cooling rate of 2°C / min to 5°C / min.

4. The heat treatment method of the dual-phase titanium alloy according to claim 1, characterized in that: The time of the furnace cooling is 60min to 240min.

5. The heat treatment method of a dual-phase titanium alloy according to any one of claims 1 to 4, characterized in that: The first annealing treatment comprises the following steps: The dual-phase titanium alloy workpiece is kept at 20° C. to 60° C. below the β phase transformation temperature for 60 min to 120 min.

6. The heat treatment method of a dual-phase titanium alloy according to any one of claims 1 to 4, characterized in that: The temperature of the second annealing treatment is 500°C to 600°C; And / or, the second annealing treatment time is 240min~360min.

7. The heat treatment method of a dual-phase titanium alloy according to any one of claims 1 to 4, characterized in that: After the furnace cooling and before the second annealing treatment, the process further includes air cooling or wind cooling the dual-phase titanium alloy workpiece to room temperature.

8. The heat treatment method of a dual-phase titanium alloy according to any one of claims 1 to 4, characterized in that: The dual-phase titanium alloy includes one of TC4 titanium alloy, TC4ELI titanium alloy, TC16 titanium alloy and TC19 titanium alloy.

9. A dual-phase titanium alloy, characterized in that: The dual-phase titanium alloy is prepared by the heat treatment method according to any one of claims 1 to 8.

10. A titanium alloy product, characterized in that: Comprising the dual-phase titanium alloy as claimed in claim 9.

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