A titanium alloy restrained welding crack test method and device

Abstract

The present invention relates to the technical field of metal material weldability evaluation, specifically to a titanium alloy restrained welding crack test method and device, the test method comprising the following steps: S1, making a T-shaped test plate; S2, assembling two T-shaped test plates and a restraint plate on a welding platform; S3, a driving device applying a side force to the restraint plate; S4, tightening the pre-tightening devices at both ends; S5, welding the test groove; S6, standing for a period of time t after welding; S7, separating the restraint plate and the T-shaped test plate; S8, checking the welding crack situation; S9, changing the restraint distance, repeating steps S2-S8, and determining the critical restraint distance Lc. The present invention makes the test plate into a T-shape, and after welding, the flange of the T-shaped test plate cannot be completely shrunk due to the limiting effect of the restraint plate, thereby achieving rigid constraint on the test plate, solving the problem of insufficient test stability in the prior art, and avoiding the problem of high cost caused by the use of complex equipment structures and control systems.

Description

Technical Field

[0001] The invention relates to the technical field of metal material weldability evaluation, and in particular to a titanium alloy restrained welding crack test method and device. Background Art

[0002] Titanium alloy has many advantages such as high strength, low density, corrosion resistance, etc. With the continuous development of industry and technology, the demand for industrial application of titanium alloy is gradually increasing, and it has broad prospects in large thick-walled load-bearing structural parts. In the welding process of such large titanium alloy structural parts, due to the characteristics of large temperature gradient and large structural constraint, the tendency of welding cold cracks is increased. Therefore, the welding crack resistance of titanium alloy needs to be studied.

[0003] In the actual production process, in order to avoid the occurrence of welding cracks, it is necessary to test the crack resistance of different materials (parent materials or welding materials) through the welding crack resistance test method, in order to obtain the welding crack resistance threshold values ​​of different materials and select materials with better crack resistance for equipment manufacturing. Or through repeated tests, according to the crack generation situation, the process parameters are optimized, and the process parameters with higher crack resistance are selected to avoid the occurrence of welding cracks.

[0004] In the 1980s, Zhang Wenyue and others published a paper titled "Research on Determination of Welding Cold Crack Sensitivity Using Flat Plate Rigid Constraint Test", which provided a method of using flat plate fixtures to achieve rigid constraint on test plates. This method has certain limitations and relies on friction to achieve fixation and constraint. On the one hand, the force provided by friction is limited. If the welding shrinkage force is greater than the friction value, the test will fail. Secondly, the friction is affected by the surface roughness of the material, and the clamping force needs to be set the same each time. The stability of the test is not easy to guarantee.

[0005] Publication number: CN104880364B A welding restraint stress adjustable test device discloses a force unit, a fixture unit, and a main unit. The fixture unit is placed between two cross bars on the main unit. The force unit is set corresponding to the weldment on the main unit and applies pressure to the weldment through an adjustable screw. The fixture unit includes an upper pressure plate, bolts, and a lower pressure plate. The weldment is tightened and fixed to the main unit through bolts passing through the upper and lower pressure plates. The invention uses the upper and lower pressure plates of the fixture unit to apply pressure to the weldment to restrain the weldment. In essence, the friction between the pressure plate and the weldment is used to achieve fixation and restraint. This kind of restraint is difficult to withstand a large restraining force, and the test stability is not high.

[0006] In 2017, Jing Hongyang and others from Tianjin University published a paper titled "Development and Experimental Research of Cold Crack Proneness Test Equipment for High-Strength Steel Welding", which provided a large-tonnage rigid restraint test machine that can realize the process of rigid restraint crack test under a certain tonnage. This method of relying on electro-hydraulic servo hydraulics to provide restraint force has some disadvantages in practical application. On the one hand, welding is carried out simultaneously during the operation of the equipment, which poses a safety hazard to welding construction workers; on the other hand, the equipment structure and control system are complex, the test cost is high, and it is not suitable for popular use.

[0007] Publication No.: CN205393818U A welding joint cold crack tendency test device based on adjustable rigid restraint discloses the ability to stretch the welding joint while welding, that is, the output shaft of the oil cylinder pulls the slider and the moving fixture to move away from the fixed fixture, so that the weld metal is stretched by external force during the cooling and crystallization process until the welding is completed. Although the invention can withstand the application of a large restraint force, the equipment structure and control system are complex, the test cost is high, and it is not suitable for popular use.

[0008] Therefore, the existing test equipment cannot solve the problems of small restraint force, insufficient test stability and high cost in rigid restraint. Summary of the invention

[0009] In view of this, the present invention aims to propose a titanium alloy restrained welding crack test method and device to solve the problems of small restraining force, insufficient test stability and high cost in the prior art.

[0010] With the continuous development of industry and technology, the demand for industrial applications of titanium alloys has gradually increased, and there is a broad prospect in large, thick-walled, high-strength, and corrosion-resistant structural parts. In the welding process of such large titanium alloy structural parts, the tendency of welding cold cracks is increased due to the characteristics of large temperature gradient and large structural constraint. Therefore, it is necessary to focus on studying and mastering the welding crack resistance of the material before practical application.

[0011] However, there are two methods used in the existing restrained welding crack test methods and equipment: the first is to use the friction between the fixture and the weldment to achieve fixation and restraint, but since the force during titanium alloy restraint welding can reach 60t, this method is difficult to meet the test requirements when applied to titanium alloy welding crack tests; the second is to achieve restraint by applying tension to both ends of the weldment during welding, but this method has complex equipment structure and control system, high test cost, and is not suitable for popular use.

[0012] In order to solve the problems of the titanium alloy restrained welding crack test method and equipment in the prior art, the present invention processes the test piece into a T-shaped structure, and installs restraint plates on both sides of the two butted T-shaped test plates. After welding is completed, when the weld joint shrinks, the flange of the T-shaped test plate is restricted by the restraint plate and cannot shrink, thereby achieving rigid restraint on the test plate. The method and device of the present invention use the rigidity of the restraint plate itself to limit and constrain the contraction of the T-shaped test plate, rather than using friction or hydraulic equipment for restraint. The fixing force provided by the present application is provided by the structure itself, which can avoid the trouble of calculating friction. It has a simple structure, is easy to produce and process, is easy to operate, has a large restraint force, can withstand multiple tests, and mechanical coordination makes the test highly stable and has low cost.

[0013] The technical solution of the present invention is achieved as follows: a titanium alloy restrained welding crack test method, comprising the following specific steps:

[0014] S1. Make a T-shaped test plate and make a groove at the end of the web of the T-shaped test plate away from the flange plate;

[0015] S2. Align the grooves of the two T-shaped test plates and assemble them on the welding platform with the restraint plates on both sides;

[0016] S3. A driving device is arranged at one end of the restraint plate away from the T-shaped test plate, and the driving device applies a lateral force to the restraint plate;

[0017] S4. Install a pre-tightening device on the side of the wing plate of the T-shaped test plate away from the web plate, and tighten the pre-tightening devices at both ends to make the two ends of the T-shaped test plate tightly combined with the restraint plate;

[0018] S5. Use welding materials and welding processes required by the test to weld the test groove;

[0019] S6. Let it stand for a period of time t after welding;

[0020] S7, unloading the test plate, first drive the device to retract, then use the tool to knock the unloading block outward, so that the restraint plate moves outward until the restraint plate and the T-shaped test plate are separated;

[0021] S8. Cut off the welding joint, inspect the welding joint, and check the occurrence of welding cracks;

[0022] S9. By changing the length of the restraint plate, the restraint distance L is changed to adjust the strength of the restraint effect, and steps S2-S8 are repeated to determine the critical restraint distance Lc.

[0023] Furthermore, in step S1, the T-shaped test plate is a titanium alloy plate, the thickness of the web of the T-shaped test plate is ≥100 mm, the width of the single-side flange of the T-shaped test plate is ≥100 mm, and the initial height of the web of the T-shaped test plate is ≥300 mm.

[0024] Furthermore, in step S2, the length of the bottom of the restraint plate ranges from 200 mm to 600 mm, with an interval of 100 mm. There are five pairs of restraint plates, with two restraint plates in each pair.

[0025] Furthermore, in step S2, two ends of the restraint plate are respectively matched with flanges of two T-shaped test plates.

[0026] Furthermore, in step S3, the lateral push force applied by the driving device is greater than the lateral sliding force of the restraint plate during compression, thereby ensuring that the restraint plate does not slide laterally during the test.

[0027] Another object of the present invention is to provide a titanium alloy restraint welding crack test device for detecting the critical restraint distance L of a T-shaped test plate. c , the critical value of crack resistance of the reaction material, used for the above-mentioned titanium alloy restrained welding crack test method, comprising a welding platform, a driving device, a pre-tightening device and two restraint plates, the two restraint plates are arranged on the welding platform with the axis of the welding platform as the symmetry axis, the two T-shaped test plate webs are butt-jointed and placed between the two restraint plates, and the two ends of the restraint plate along the length direction of the T-shaped test plate web are respectively abutted against the flanges of the T-shaped test plate;

[0028] The driving device is provided on one side of the restraining plate away from the web of the T-shaped test plate, and the driving device is used to apply a lateral force to the restraining plate;

[0029] The pre-tightening device is provided on a side of the flange of the T-shaped test plate away from the restraining plate, and the pre-tightening device is used to make the T-shaped test plate abut against the restraining plate.

[0030] Furthermore, the cross-section of the restraint plate is an isosceles trapezoid, the upper base length of the restraint plate is L1, the internal angle between the upper base and the waist of the restraint plate is θ1, the internal angle θ1 is greater than 90°, the angle between the flange and the web of the T-shaped test plate is θ2, the angle θ2 is greater than 90°, the upper base length L1 of the restraint plate is not less than the sum of the web heights H1 of the two T-shaped test plates and the weld gap H2, that is, L1=2*H1+H2, the internal angle θ1 is equal to the angle θ2, that is, θ1=θ2.

[0031] Furthermore, a plurality of the driving devices are provided, and the plurality of the driving devices are symmetrically arranged on the lower bottom sides of the two restraint plates, and the movement direction of the extended end of the driving device is parallel to the welding platform.

[0032] Furthermore, two pre-tightening devices are provided, and the two pre-tightening devices are symmetrically arranged at both ends of the welding platform. The pre-tightening device includes a pre-tightening block and a pre-tightening member, and the pre-tightening member is fixed to the welding platform via the pre-tightening block.

[0033] Furthermore, it also includes ventilation grooves and multiple unloading blocks, the unloading blocks are evenly distributed on the side of the restraint plate away from the welding platform, the ventilation grooves are arranged on the welding platform, and the welds of the two T-shaped test plates connected to each other are parallel to the ventilation grooves.

[0034] Compared with the prior art, 1. The titanium alloy restrained welding crack test method and device of the present invention have the following advantages:

[0035] The present invention manufactures the test plate into a T shape, and arranges the restraint plates on both sides of the two butted T-shaped test plates. After welding is completed, when the weld joint shrinks, the flanges of the T-shaped test plates are restricted by the restraint plates and cannot shrink, thereby achieving rigid constraint on the test plates, solving the problems of small restraint force and insufficient test stability in the prior art, and avoiding the problem of high cost caused by the use of complex equipment structures and control systems.

[0036] 2. The test method of the present invention can play a role in quantitative evaluation. Through the critical parameters of welding crack resistance, it can achieve the purpose of quantitatively distinguishing the welding crack resistance of different materials and the advantages and disadvantages of different welding processes. In actual use, it plays the purpose of improving the welding quality of equipment manufacturing, improving the performance of research and development materials, and improving the accuracy of welding process optimization.

[0037] 3. The present invention realizes the restraint adjustable welding crack test process by adjusting the distance of the restraint plates, and obtains the crack resistance characteristic values ​​of different materials. The test process is safer and more stable, the structure of the device is simple, and the cost is low. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] The accompanying drawings constituting a part of the present invention are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the accompanying drawings:

[0039] Figure 1 A schematic diagram of the structure of the device in the present invention;

[0040] Figure 2 A front view of the device of the present invention;

[0041] Figure 3 A schematic cross-sectional view of a T-shaped test plate in the present invention;

[0042] Figure 4 A schematic cross-sectional view of a restraint plate in the present invention;

[0043] Figure 5 Schematic diagram of the installation of the T-shaped test plate 6 and the restraint plate in the present invention;

[0044] Figure 6 Image of cracks detected in the present invention.

[0045] Description of reference numerals:

[0046] 1. Welding platform; 2. Driving device; 3. Pre-tightening device; 301. Pre-tightening block; 302. Pre-tightening member; 303. Threaded hole; 4. Restraint plate; 5. Unloading block; 6. T-shaped test plate; 7. Ventilation groove. DETAILED DESCRIPTION

[0047] In order to make the technical means, objectives and effects of the present invention easy to understand, the embodiments of the present invention are described in detail below with reference to specific drawings.

[0048] It should be noted that all the terms used in the present invention to indicate directionality and position, such as "upper", "lower", "left", "right", "front", "back", "vertical", "horizontal", "inside", "outside", "top", "lower", "lateral", "longitudinal", "center", etc., are only used to explain the relative positional relationship and connection status between the components in a certain state, and are only for the convenience of describing the present invention, rather than requiring the present invention to be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the descriptions of "first", "second", etc. in the present invention are only used for descriptive purposes, and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of the indicated technical features.

[0049] In the description of the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0050] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "illustrative embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0051] An object of the present invention is to disclose a titanium alloy restrained welding crack test method.

[0052] S1, making a T-shaped test plate 6, and making a groove at one end of the web of the T-shaped test plate 6 away from the wing plate;

[0053] S2, butt the grooves of the two T-shaped test plates 6 together with the restraint plates 4 on both sides and assemble them on the welding platform 1;

[0054] S3, a driving device 2 is arranged at one end of the restraining plate 4 away from the T-shaped test plate 6, and the driving device 2 applies a lateral force to the restraining plate 4;

[0055] S4. A pre-tightening device 3 is arranged on the side of the wing plate of the T-shaped test plate 6 away from the web plate, and the pre-tightening devices 3 at both ends are tightened so that the two ends of the T-shaped test plate 6 and the restraining plate 4 are tightly combined;

[0056] S5. Use welding materials and welding processes required by the test to weld the test groove;

[0057] S6. Let it stand for a period of time t after welding;

[0058] S7, unloading the test plate, first the driving device 2 is recovered, and then the unloading block 5 is knocked outwardly with a tool to make the restraining plate 4 move outwardly until the restraining plate 4 and the T-shaped test plate 6 are separated;

[0059] S8. Cut off the welding joint, inspect the welding joint, and check the occurrence of welding cracks;

[0060] S9, by changing the length of the restraining plate 4, changing the restraining distance L, adjusting the strength of the restraining effect, repeating steps S2-S8, and determining the critical restraining distance Lc; the greater the restraining force is when the restraining distance L is shortened, the more prone to cracks. Therefore, the usual adjustment method is to shorten the restraining distance several times until welding cracks appear, and obtain the shortest critical restraining distance Lc without welding cracks. c .

[0061] The test plate is made into a T shape, and the restraint plate 4 is arranged on both sides of the two butted T-shaped test plates 6. After welding is completed, when the weld joint shrinks, the flange of the T-shaped test plate 6 is restricted by the restraint plate 4 and cannot complete the contraction, thereby achieving rigid constraint on the test plate, solving the problems of small restraint force and insufficient test stability in the prior art, and avoiding the problem of high cost caused by the use of complex equipment structure and control system; the driving device 2 and the pre-tightening device 3 can respectively limit the displacement of the restraint plate 4 and the T-shaped test plate 6, so that the restraint plate 4 and the T-shaped test plate 6 become a rigid whole, accurately simulate the restraint conditions, and ensure the accuracy of the test; the restraint distance L is adjusted by adjusting the length of the restraint plate 4, and the restraint distance L is changed to adjust the strength of the restraint effect. After repeated tests, the generation of welding cracks under different restraint distances L can be determined, and finally the critical restraint distance Lc can be determined.

[0062] This setting utilizes the structure of the T-shaped test plate 6 and the restraint plate 4 to achieve rigid constraint on the test plate. It has a simple structure and is easy to process, use and maintain. It also has a large restraint force and high test stability and repeatability, solving the problems of small restraint force and insufficient test stability in the prior art. It also avoids the problem of high cost caused by the use of complex equipment structures and control systems. It can accurately simulate restraint conditions, improve the accuracy of the test, and ensure the smooth progress of the test. By adjusting the length of the restraint plate 4 and optimizing the welding process parameters, it is possible to systematically study the influence of the restraint on welding cracks, providing important parameters for practical engineering applications, effectively reducing the generation of welding cracks, and improving the quality and reliability of titanium alloy welded joints.

[0063] Specifically, in step S1, the T-shaped test plate 6 is a titanium alloy plate, the thickness of the web of the T-shaped test plate 6 is ≥100 mm, the width of the single-side flange of the T-shaped test plate 6 is ≥100 mm, and the initial height of the web of the T-shaped test plate 6 is ≥300 mm.

[0064] The T-shaped test plate 6 is configured to be a titanium alloy plate, and the initial height of the web of the T-shaped test plate 6 is not less than 300 mm, which can ensure that the restraint distance L is greater than the critical restraint distance Lc of the test plate, thereby avoiding the situation where the critical restraint distance Lc of the material cannot be obtained due to insufficient restraint distance L after the T-shaped test plate 6 is processed, thereby avoiding wasting test materials and time. The size setting of the T-shaped test plate 6 can improve the stability of the restraint distance L test, and avoid affecting the test results due to excessive local pressure.

[0065] Preferably, the T-shaped test plate 6 is a TC4 titanium alloy plate.

[0066] TC4 titanium alloy is a commonly used titanium alloy material with good mechanical properties, corrosion resistance and weldability. It is suitable for the manufacture of various structures. Through the restrained welding crack test, it can fully demonstrate the crack sensitivity of its welding process and provide reliable data for subsequent material and process optimization.

[0067] Specifically, the T-shaped test plate 6 is machined.

[0068] Specifically, in step S2, the length range of the upper bottom of the restraint plate 4 is 200mm~600mm, with an interval of 100mm as one level. There are 5 pairs of restraint plates 4, 2 in each pair, that is, the restraint distance is the length of the upper bottom of the restraint plate. Multi-level adjustment can be set according to test needs.

[0069] The length range of the upper bottom of the restraint plate 4 is 200mm~600mm, with an interval of 100mm as one level, which can directly affect the degree of restraint applied to the welding area. A longer restraint plate 4 means a smaller restraint force, while a shorter restraint plate 4 means a larger restraint force. The upper bottom of the restraint plate 4 can cover the critical restraint distance Lc of the test titanium alloy material within this range, ensuring the normal progress of the test, facilitating the replacement of the restraint plate 4 according to different restraint conditions, and analyzing the crack sensitivity under different conditions, so that the results are more reliable and repeatable; multiple pairs of restraint plates 4 are arranged, with two in each pair, so that they are respectively installed on both sides of the T-shaped test plate 6 to ensure that the applied restraint force is uniform and symmetrical, better simulate the stress conditions in the actual welding process, and ensure the validity of the test results.

[0070] This setup can systematically evaluate the effect of the length of the restraint plate 4 on the welding cracks, so as to find a critical restraint distance Lc, at which the welding cracks begin to appear significantly, which helps to improve the welding technology, improve the welding quality and reduce the risk of failure caused by welding cracks.

[0071] Specifically, in step S2 , two ends of the restraint plate 4 are respectively matched with flanges of two T-shaped test plates 6 .

[0072] By cooperating the two ends of the restraint plate 4 with the flanges of the T-shaped test plate 6, it can be ensured that the positions of the two T-shaped test plates 6 are accurately aligned before welding, and the restraint force can be evenly applied to the test plates to simulate the restraint conditions in actual applications, enhance the stability of the entire device structure, and prevent deformation or other defects caused by insufficient or excessive restraint during the welding process.

[0073] This setting simplifies the assembly process, makes it easier for operators to position and fix the test plate, reduces the possibility of assembly errors, improves assembly accuracy, ensures welding quality and consistency, and can effectively enhance the restraint effect, so that the test can accurately reflect the formation of welding cracks under different restraint conditions, which is closer to the actual restraint state in the welding process and can be better applied in actual production.

[0074] Specifically, in step S3, the lateral push force applied by the driving device 2 is greater than the lateral sliding force of the restraining plate 4 during the compression process, thereby ensuring that the restraining plate 4 does not slide laterally during the test.

[0075] The lateral push force applied by the driving device 2 is greater than the lateral sliding force component of the restraint plate 4 during the compression process, which can ensure that the restraint plate 4 remains in a fixed position during the entire test process and will not move due to thermal stress or changes in restraint force during welding; by providing sufficient lateral push force, the required restraint conditions can be effectively maintained and the reduction of restraint strength due to the sliding of the restraint plate 4 can be prevented.

[0076] This setting can avoid changes in restraint conditions, truly simulate actual working conditions, simplify the data analysis process, make the results more intuitive and easy to interpret, ensure the reliability of experimental results, and prevent equipment damage or personal injury.

[0077] Another object of the present invention is to disclose a titanium alloy restraint welding crack test device for detecting the critical restraint distance L of the T-shaped test plate 6. c , comprising a welding platform 1, a driving device 2, a pre-tightening device 3 and two restraining plates 4, the two restraining plates 4 are arranged on the welding platform 1 with the axis of the welding platform 1 as the symmetric axis, the webs of two T-shaped test plates 6 are butt-jointed and placed between the two restraining plates 4, and the two ends of the restraining plates 4 along the length direction of the webs of the T-shaped test plates 6 are respectively butted against the flanges of the T-shaped test plates 6;

[0078] A driving device 2 is provided on one side of the restraining plate 4 away from the web of the T-shaped test plate 6, and the driving device 2 is used to apply a lateral force to the restraining plate 4;

[0079] A pre-tightening device 3 is provided on the side of the flange of the T-shaped test plate 6 away from the restraining plate 4 , and the pre-tightening device 3 is used to make the T-shaped test plate 6 abut against the restraining plate 4 .

[0080] By processing the test plate into a T shape, the weld joint shrinks after welding is completed, and the flanges of the T-shaped test plate 6 are acted upon by the restraint plates 4 on both sides to limit the shrinkage of the T-shaped test plate 6. After the test is completed, the crack condition of the weld joint is detected to determine the critical restraint distance Lc; by applying a side force to the restraint plate 4 through the driving device 2, the restraint condition of the T-shaped test plate 6 during the welding process can be accurately adjusted and controlled, which is helpful for evaluating the mechanical properties of the weld joint and optimizing the welding process parameters; the pre-tightening device 3 makes the T-shaped test plate 6 tightly abut against the restraint plate 4, which can simulate the restraint state of the test piece in the actual welded structure, and is helpful for more accurate prediction and evaluation of the performance and reliability of the welded structure under use conditions; by changing the restraint conditions and measuring the restraint distance L, researchers can gain an in-depth understanding of the formation laws of welding cracks and the mechanical properties of the welded joint under different restraint conditions, thereby knowing the optimization and improvement of the welding process. The critical restraint distance Lc is one of the important parameters for evaluating the welded joint.

[0081] The device has a reasonable structural design, easy operation and reliable results. By replacing the restraint plates 4 of different sizes, a welding crack test process with adjustable restraint can be realized, and the crack resistance characteristic values ​​of different materials can be obtained. The test process is safe, stable, repeatable and low-cost, providing experimental and data support for material optimization and process optimization of titanium alloy welding structures.

[0082] Specifically, the cross section of the restraint plate 4 is an isosceles trapezoid, the length of the upper base of the restraint plate 4 is L1, the inner angle between the upper base and the waist of the restraint plate 4 is θ1, and the inner angle θ1 is greater than 90°.

[0083] The isosceles trapezoidal design of the restraint plate 4 makes the angle between the contact surface along the two waists of the restraint plate 4 and the flange of the T-shaped test plate 6 and the restraining force greater than 90°, that is, this surface is an inclined surface. In this way, when the T-shaped test plate 6 shrinks after welding and generates a force, this force is decomposed when it acts on the restraint plate 4. The force on the joint surface of the restraint plate and the T-shaped plate can be decomposed into axial force and lateral force. The lateral force makes the restraint plate have a tendency to slide to the edge. During the test, since the side top force is greater than the side sliding force, the restraint plate and the test plate are tightly combined into a rigid body. After the test, the side top device is recovered and the side top force is withdrawn. Due to the side sliding force, the restraint plate and the test T-shaped plate can be disassembled by gently applying external force to the unloading block.

[0084] The arrangement of the restraint plate 4 can provide better support and restraint, ensure the normal progress of the test, facilitate the separation of the restraint plate 4 and the T-shaped test plate 6, and the T-shaped test plate 6 can be removed without damaging the restraint plate 4, thereby reducing production costs, improving work efficiency, and helping to improve the detection accuracy and reliability of the device.

[0085] Specifically, the included angle between the flange and the web of the T-shaped test plate 6 is θ2, and the included angle θ2 is greater than 90°.

[0086] The angle between the flange and the web of the T-shaped test plate 6 is set to be an obtuse angle, which facilitates the installation and separation of the restraint plate 4 and the T-shaped test plate 6, reduces the precision requirements for the restraint plate 4 and the T-shaped test plate 6, and facilitates production and processing.

[0087] Specifically, the upper bottom of the restraint plate 4 is arranged parallel to the web of the T-shaped test plate 6 , and the two sides of the restraint plate 4 are respectively in contact with the two flanges of the T-shaped test plate 6 .

[0088] This arrangement can ensure the precise docking of the T-shaped test plate 6 and the restraint plate 4, so that the force can be evenly distributed, thereby improving the accuracy and repeatability of the test results.

[0089] Specifically, the flatness of the two surfaces where the restraint plate 4 and the T-shaped test plate 6 abut is no greater than 0.05 mm.

[0090] This arrangement allows the two sides of the restraint plate 4 to fully contact the flanges of the T-shaped test plate 6, evenly distributing the restraining force and avoiding deformation of the restraint plate 4 caused by excessive local pressure, which would affect the test results.

[0091] Specifically, the upper bottom length L1 of the restraint plate 4 is not less than the sum of the web height H1 of the two T-shaped test plates 6 and the weld gap H2, that is, L1=2*H1+H2, and the internal angle θ1 is equal to the included angle θ2, that is, θ1=θ2.

[0092] Preferably, θ1=θ2=96°.

[0093] The relationship between the upper bottom length of the restraint plate 4 and the T-shaped test plate 6 and the weld gap ensures that the restraint conditions meet the design requirements, can accurately reflect the restraint distance L, and avoids the influence of the measurement accuracy due to the error of the device parts.

[0094] Specifically, the width of the restraint plate 4 is the same as the thickness of the web of the T-shaped test plate 6 .

[0095] This arrangement can improve the structural rigidity of the restraint plate 4, ensure that the restraint plate 4 provides sufficient restraint force, and avoid excessive deformation of the restraint plate 4 due to excessive shrinkage force after welding of the T-shaped test plate 6, thereby affecting the accuracy of the test results.

[0096] Specifically, a plurality of driving devices 2 are provided, and the plurality of driving devices 2 are symmetrically arranged on the lower bottom sides of the two restraint plates 4 .

[0097] The arrangement of multiple drive devices 2 symmetrically distributed on the lower bottom side of the two restraint plates 4 allows the forces and restrictions in the test process to be applied and adjusted more quickly, ensuring that the lower bottom of the restraint plate 4 is subjected to uniform force, and the two restraint plates 4 are subjected to forces acting in the same direction and in opposite directions, thereby avoiding uneven force. At the same time, the force on a single drive device 2 is reduced, thereby avoiding a situation in which a single drive device 2 causes excessive local stress on the restraint plate 4 and damages the restraint plate 4.

[0098] Specifically, the driving device 2 is a jack, and the moving direction of the extended end of the driving device 2 is parallel to the welding platform 1 .

[0099] The driving device 2 is configured as a jack, which has the advantages of simple structure, small size and light weight, small operating force, flexible piston lifting and lowering, fast speed, and easy operation; the movement direction of the extended end of the driving device 2 is parallel to the welding platform 1, which can ensure that the force applied by the driving device 2 acts on the restraint plate 4, preventing the restraint plate 4 from being separated from the T-shaped test plate 6 by the force, affecting the measurement of the restraint distance L, and ensuring the smooth progress of the test.

[0100] Specifically, the driving device 2 may also be a hydraulic system or an electric cylinder.

[0101] Specifically, the pre-tightening device 3 includes a pre-tightening block 301 and a pre-tightening member 302 , and the pre-tightening member 302 is fixed on the welding platform 1 via the pre-tightening block 301 .

[0102] The preload member 302 is fixed to the welding platform 1 via the preload block 301, which facilitates the installation, replacement and maintenance of the preload member 302. During the test, the preload block 301 can ensure that the preload member 302 does not deviate, and ensure that the T-shaped test plate 6 and the restraint plate 4 form a rigid integral structure. When the weld shrinks and deforms due to welding, it is restricted by the restraint plate 4, thereby ensuring the smooth progress of the test.

[0103] Preferably, the pre-tightening block 301 is provided with a threaded hole 303 , the pre-tightening member 302 is a stud, and the pre-tightening member 302 passes through the threaded hole 303 and abuts against the flange of the T-shaped test plate 6 .

[0104] The preload member 302 is a stud, which passes through the threaded hole 303 and abuts against the T-shaped test plate 6. The extension length of the preload member 302 can be adjusted according to the size of the T-shaped test plate 6. The structure is simple, the reliability is high, the processing is easy, and the production cost is low.

[0105] Preferably, the pre-tightening member 302 may be a jack, a hydraulic cylinder, or an electric cylinder.

[0106] Preferably, the pre-tightening device 3 is provided with a plurality of pre-tightening members 302 , and the pre-tightening block 301 is provided with a plurality of threaded holes 303 .

[0107] The provision of multiple pre-tightening members 302 can evenly distribute the pre-tightening force, thereby preventing the T-shaped test plate 6 from being subjected to uneven force and excessive local stress, thereby affecting the conduct of the test.

[0108] Preferably, the preload block 301 is connected to the welding platform 1 by one or more of welding, bonding or screw connection.

[0109] The pre-tightening block 301 is connected to the welding platform 1 by welding, so that the pre-tightening block 301 can withstand a large pre-tightening force and has high reliability and stability; the pre-tightening block 301 is connected by bonding, which is quick and easy and can be installed without machining the parts; the pre-tightening block 301 is connected by screws, which has a detachable function, is easy and quick to install, can withstand a high pre-tightening force, and has high stability and reliability.

[0110] Specifically, two pre-tightening devices 3 are provided, and the two pre-tightening devices 3 are symmetrically arranged at two ends of the welding platform 1 .

[0111] The pre-tightening device 3 can be kept on the same axis to prevent the pre-tightening force from being offset and affecting the close contact between the T-shaped test plate 6 and the restraint plate 4, thereby ensuring the smooth progress of the test.

[0112] Specifically, it also includes a plurality of unloading blocks 5 , which are evenly distributed on a side of the restraining plate 4 away from the welding platform 1 .

[0113] The unloading block 5 is arranged on the restraining plate 4. After the test is finished, the unloading block 5 is struck to make the restraining plate 4 slide sideways until the restraining plate 4 and the T-shaped test plate 6 interact with each other, and the welding test plate is removed to complete the unloading.

[0114] Specifically, it also includes a ventilation groove 7 , which is arranged on the welding platform 1 , and the welds of the two butted T-shaped test plates 6 are parallel to the ventilation groove 7 .

[0115] The provision of the ventilation groove 7 helps to provide inert gas protection to the back during welding and to isolate the groove of the test plate from the bottom plate, thereby improving welding quality, preventing element contamination, and improving the convenience and controllability of the test.

[0116] Example 1

[0117] A quantitative evaluation process for the welding crack resistance of titanium alloy is specifically designed.

[0118] S1. Make a test device. The test restraint distance L ranges from 600mm to 200mm, with each 100mm interval as one level. A total of 5 pairs of restraint plates 4 with different restraint distances are made, with 2 plates in each pair. The material of the restraint plate 4 is 304 stainless steel with a thickness of 50mm. The remaining device parts are all 1 set, and the material is all 304 stainless steel. The structural diagram of the cross section of the restraint plate 4 is as follows: Figure 4 shown.

[0119] S2. Make a T-shaped test plate 6. A TC4 titanium alloy plate with a thickness of 50 mm is machined into a T-shaped plate, and the initial restraint distance L is 600 mm. After each test, if there is no crack, the restraint distance L is shortened, and it is repeatedly used. Only the size near the groove is processed to shorten the restraint distance L. Repeat the test until cracks appear. The cross section of the T-shaped test plate 6 is as follows: Figure 3 As shown, the cracks Figure 6 shown.

[0120] S3, assemble the T-shaped test plate 6. Assemble the T-shaped test plate 6 and the restraint plate 4 tightly. At the same time, the jacks on both sides apply lateral force to prevent the restraint plate 4 from sliding sideways during the welding test. That is, when the force of the jack is greater than the sliding force of the restraint plate 4 during the compression process, the structure is always in a rigid state. Figure 1 , Figure 2 and Figure 5 shown.

[0121] S4. Welding. Welding is performed according to the test requirements. In this case, TIG welding is used, and only the base welding is performed, because the cooling speed is the fastest during the base welding process, the stress concentration is the greatest, and cracks are most likely to occur.

[0122] S5, unloading. After keeping the restraint for 24 hours, it reaches a stable state and needs to be unloaded for flaw detection to check the crack generation. First, loosen the hydraulic jacks on both sides, and then knock on the unloading block 5 to make the restraint plate 4 slide sideways. In this process, the test plate can shrink freely. Until there is no interaction force between the restraint plate 4 and the welding test plate, the welding test plate can be easily removed to complete the unloading.

[0123] S6. Repeat the test until the critical restraint distance Lc is obtained. By shortening the restraint distance and repeating the above test, the critical value of crack resistance can be obtained.

[0124] S7. The results are shown in Table 1. The test results show that the critical restraint distance Lc of TC4 is 300 mm, which is the shortest restraint distance without welding cracks. Under the same test conditions, this value has quantitative comparison value and is the characteristic value of crack resistance of the material under this test condition.

[0125] Table 1 TC4 titanium alloy test results

[0126]

[0127] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A titanium alloy restrained welding crack test method, characterized in that: The specific steps are as follows: S1. A T-shaped test plate (6) is manufactured, and a groove is manufactured at one end of the web of the T-shaped test plate (6) away from the flange; the T-shaped test plate (6) is a titanium alloy plate, the thickness of the web of the T-shaped test plate (6) is ≥100 mm, the width of the single-side flange of the T-shaped test plate (6) is ≥100 mm, and the initial height of the web of the T-shaped test plate (6) is ≥300 mm; S2. Align the grooves of the two T-shaped test plates (6) and assemble them on the welding platform (1) with the restraint plates (4) on both sides; the length of the upper bottom of the restraint plates (4) ranges from 200 mm to 600 mm, with a spacing of 100 mm per level. There are five pairs of restraint plates (4), each pair has two, and the width of the restraint plates 4 is the same as the thickness of the web of the T-shaped test plate 6; S3, a driving device (2) is arranged at one end of the restraining plate (4) away from the T-shaped test plate (6), and the driving device (2) applies a lateral pushing force to the restraining plate (4); S4. A pre-tightening device (3) is arranged on the side of the wing plate of the T-shaped test plate (6) away from the web plate, and the pre-tightening devices (3) at both ends are tightened so that the two ends of the T-shaped test plate (6) are tightly combined with the restraining plate (4); S5. Use welding materials and welding processes required by the test to weld the test groove; S6. Let it stand for a period of time t after welding; S7, unloading the test plate, first the driving device (2) is recovered, and then the unloading block (5) is knocked outwardly using a tool, so that the restraining plate (4) is displaced outwardly until the restraining plate (4) and the T-shaped test plate (6) are separated; S8. Cut off the welding joint, inspect the welding joint, and check the occurrence of welding cracks; S9, by changing the length of the restraining plate (4), changing the restraining distance L, adjusting the strength of the restraining effect, repeating steps S2-S8, and determining the critical restraining distance Lc; The test device comprises a welding platform (1), a driving device (2), a pre-tightening device (3) and two restraining plates (4); the two restraining plates (4) are arranged on the welding platform (1) with the axis of the welding platform (1) as the axis of symmetry; the webs of the two T-shaped test plates (6) are aligned and placed between the two restraining plates (4); the two ends of the restraining plates (4) along the length direction of the webs of the T-shaped test plates (6) are respectively in contact with the flanges of the T-shaped test plates (6); The cross section of the restraint plate (4) is an isosceles trapezoid, the length of the upper base of the restraint plate (4) is L1, the internal angle between the upper base and the waist of the restraint plate (4) is θ1, the internal angle θ1 is greater than 90°, the angle between the flange and the web of the T-shaped test plate (6) is θ2, the angle θ2 is greater than 90°, the length L1 of the upper base of the restraint plate (4) is not less than the sum of the height H1 of the webs of the two T-shaped test plates (6) and the weld gap H2, that is, L1=2*H1+H2, the internal angle θ1 is equal to the angle θ2, that is, θ1=θ2; the driving device (2) is provided on the side of the restraint plate (4) away from the web of the T-shaped test plate (6), and the driving device (2) is used to apply a lateral force to the restraint plate (4); The pre-tightening device (3) is provided on the side of the flange of the T-shaped test plate (6) away from the restraining plate (4), and the pre-tightening device (3) is used to make the T-shaped test plate (6) abut against the restraining plate (4).

2. The titanium alloy restrained welding crack test method according to claim 1, characterized in that: In step S2, the two ends of the restraint plate (4) are respectively matched with the flanges of two T-shaped test plates (6).

3. The titanium alloy restrained welding crack test method according to claim 1, characterized in that: In step S3, the lateral push force applied by the driving device (2) is greater than the lateral sliding force of the restraint plate during the compression process, thereby ensuring that the restraint plate does not slide laterally during the test.

4. The titanium alloy restrained welding crack test method according to claim 1, characterized in that: A plurality of the driving devices (2) are provided, and the plurality of the driving devices (2) are symmetrically arranged on the lower bottom sides of the two restraining plates (4), and the movement direction of the extended end of the driving device (2) is parallel to the welding platform (1).

5. The titanium alloy restrained welding crack test method according to claim 1, characterized in that: Two pre-tightening devices (3) are provided, and the two pre-tightening devices (3) are symmetrically arranged at two ends of the welding platform (1). The pre-tightening device (3) comprises a pre-tightening block (301) and a pre-tightening member (302), and the pre-tightening member (302) is fixed to the welding platform (1) via the pre-tightening block (301).

6. The titanium alloy restrained welding crack test method according to claim 1, characterized in that: It also comprises a ventilation groove (7) and a plurality of unloading blocks (5), wherein the unloading blocks (5) are evenly distributed on a side of the restraining plate (4) away from the welding platform (1), the ventilation groove (7) is arranged on the welding platform (1), and the welds of the two butt-jointed T-shaped test plates (6) are parallel to the ventilation groove (7).

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