Shear strength test device and test method for titanium alloy laser wire-filled lap joints

Abstract

The present invention proposes a shear strength test device and a test method for titanium alloy laser wire-filled lap joints, which belongs to the field of mechanical property testing of titanium alloy lap joints. The present invention solves the problem that there is no shear strength test for titanium alloy laser wire-filled lap joints. There are two adjustment positioning plates, which are respectively arranged on both sides of the lap joint. There are two jaws, which are respectively arranged at both ends of the lap joint and the adjustment positioning plate. The lap joint is clamped with the adjustment positioning plate. The jaws are arranged in the jaw seat. The jaws are connected to the clamping cylinder. The jaws are clamped by the clamping cylinder. The clamping cylinder passes through the jaw seat and is connected to the wire column. The outer sides of the two adjustment positioning plates are provided with left and right positioning plates, and the upper and lower positioning plates are provided on the upper and lower sides of the adjustment positioning plate. It is mainly used for shear strength testing of titanium alloy laser wire-filled lap joints.

Description

Technical Field

[0001] The invention belongs to the field of mechanical property testing of titanium alloy lap joints, and particularly relates to a shear strength testing device and a testing method for titanium alloy laser wire-filling lap joints. Background Art

[0002] Titanium alloys have the advantages of low density, high specific strength, excellent corrosion resistance and fatigue resistance, and are widely used in naval equipment and shipbuilding industries. For example, the pressure hulls of the "Jiaolong" and "Fendouzhe" deep-sea manned submersibles are both made of titanium alloys. Since titanium alloys are difficult to manufacture and form, welding becomes a necessary processing method. Laser wire welding has many advantages such as low heat input, narrow heat-affected zone, high welding efficiency, and small residual stress and deformation of welded joints. It has gradually begun to be used in the field of titanium alloys. After welding, the weld microstructure of titanium alloys is mostly composed of coarse columnar microstructure, needle-like microstructure, basket microstructure or Widmanstatten microstructure. Unless the beneficial components of the filler wire are supplemented or heat treated, it is difficult to obtain equiaxed microstructure or dual-state microstructure in the weld.

[0003] Although the addition of welding wire in the titanium alloy laser wire welding process can replenish the burned elements and refine the weld structure, the thermal cycle in the welding process will still make the weld structure extremely complex and produce an uneven gradient distribution of performance. Therefore, it is of great significance to conduct performance testing on titanium alloy laser wire welding joints to ensure the safe service of titanium alloy components.

[0004] With the gradual expansion of the application of titanium alloy laser wire welding components, its welding structure form has also diversified. In addition to the conventional titanium alloy plate butt joint, the lap joint form is becoming more and more common. The inspection standards and detection method system of butt welding joints are relatively complete and mature, but compared with them, the inspection methods and means of lap joints are dwarfed, which to a certain extent limits the promotion and application of this joint form. An effective, accurate and quantitative lap joint shear strength evaluation method is an important means to test the reliability of lap joints. Therefore, it is urgently necessary to develop a method for shear strength detection of titanium alloy laser wire welding lap joints. This method should realize the quantitative evaluation of the shear strength of lap joints and provide new ideas for standardizing the quality of titanium alloy laser wire welding lap joints. Summary of the invention

[0005] In view of this, the present invention aims to propose a shear strength testing device and a testing method for titanium alloy laser wire-filled lap joints, so as to solve the problem that there is currently no shear strength testing of titanium alloy laser wire-filled lap joints.

[0006] To achieve the above-mentioned purpose, the present invention adopts the following technical scheme: a shear strength testing device for titanium alloy laser wire-filled lap joints, which includes a jaw seat, a clamping cylinder, a jaw, an adjustment positioning plate, left and right positioning plates, an upper and lower positioning plate and a wire column, the number of the adjustment positioning plates is two, and the two adjustment positioning plates are respectively arranged on both sides of the lap joint, the number of the jaws is two, and the two jaws are respectively arranged at both ends of the lap joint and the adjustment positioning plate, the lap joint is clamped with the adjustment positioning plate, the jaw is arranged in the jaw seat, the jaw is connected to the clamping cylinder, the jaw is clamped by the clamping cylinder, the clamping cylinder is connected to the wire column after passing through the jaw seat, the outer sides of the two adjustment positioning plates are provided with left and right positioning plates, and the upper and lower sides of the adjustment positioning plate are provided with upper and lower positioning plates.

[0007] Furthermore, positioning bolts are provided on the left and right positioning plates.

[0008] Furthermore, a fixing block is provided on the clamping cylinder, and the clamping cylinder is connected to the jaws via the fixing block.

[0009] The present invention also provides a testing method for a titanium alloy laser wire-filled lap joint shear strength testing device, which comprises the following steps:

[0010] Step 1: Laser wire-filling welding is performed on titanium alloy plates of the same model and thickness. Two lap welds are obtained by laser wire-filling welding with a dual-beam and dual-wire feeding system at the same time. After discarding the light-emitting position part and the light-stopping position part of the welded part, a lap joint with a specified weld length l and lap length e is obtained;

[0011] Step 2: Measure the lap joint to obtain the weld width b and weld height a;

[0012] Step 3: Perform a shear strength test on the lap joint, install the lap joint in the test device, press the lap joint by adjusting the positioning plate, so that the overall force of the adjustment positioning plate and the lap joint is on the central axis, clamp the adjustment positioning plate and the lap joint by the jaws, clamp the adjustment positioning plate and the lap joint by the jaw seat and the clamping cylinder, clamp and position the adjustment positioning plate and the lap joint in the left and right directions by the left and right positioning plates and positioning bolts, and clamp and position the adjustment positioning plate and the lap joint in the upper and lower directions by the upper and lower positioning plates, and complete the clamping of the lap joint;

[0013] Step 4: Use a universal testing machine to test the shear strength of the lap joint;

[0014] Step 5: Stretch the lap joint and record the test force-beam displacement curve. The maximum test force on the curve is the shear force of the sample.

[0015] Step 6: The shear strength of the lap joint is obtained by dividing the shear force F measured by the universal testing machine by the area of ​​the weld region of the lap joint.

[0016] Furthermore, the test method processes multiple lap joints of the same size, tests the multiple lap joints to obtain multiple shear strengths of the multiple lap joints, calculates the average value of the multiple shear strength values, and retains two decimal places in the result.

[0017] Furthermore, in step 1, the thickness T of the titanium alloy plate is 5 mm, the weld length l is 20 mm, and the overlap length e is 5 mm.

[0018] Furthermore, in step 1, the welding environment condition is 20°C±5°C, and the relative humidity is between 20% and 50%.

[0019] Furthermore, the shear strength test is carried out within 48 hours after welding.

[0020] Furthermore, in step 2, a vernier caliper is used to measure the lap joint, and the weld width b is 3-5 mm, and the weld height a is 3-5 mm.

[0021] Furthermore, the shear strength of the lap joint in step 6 is calculated by the following formula:

[0022]

[0023] Where: τ is the shear strength, MPa; F 1 is the horizontal left shear force, kN; F 2 is the horizontal rightward shear force, kN; S 1 is the effective cross-sectional area of ​​the left lap weld, mm 2 ; S 2 is the effective cross-sectional area of ​​the right lap weld, mm 2 .

[0024] Compared with the prior art, the beneficial effects of the present invention are as follows: the present invention provides a test device and a test method for detecting the shear strength of titanium alloy laser wire-filled lap joints, which can quantitatively evaluate the shear resistance of lap joints. The test device provided by the present invention plays a role in accurately measuring the shear strength of titanium alloy lap joint welding, and the test accuracy is high. The force of the lap joint can be placed on the central axis, thereby ensuring the accuracy of the shear results measured in the test. The test device uses multiple clamping and centering devices to fix and position the lap joint, which can effectively ensure the shear test accuracy and firm clamping of the lap joint, and will not cause displacement or offset during the shear test to cause inaccurate test results. The present invention prepares a sample form that can be accurately used to measure the welding quality of the lap joint, and the test steps and test results provided can quantitatively evaluate the shear resistance of the joint. The method is easy to implement, simple to operate, objective and accurate results, and high test stability and repeatability. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] 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:

[0026] Figure 1 This is a schematic diagram of the internal three-dimensional structure of a titanium alloy laser wire-filled lap joint shear strength testing device according to the present invention;

[0027] Figure 2 It is a schematic diagram of the three-dimensional structure of a shear strength testing device for titanium alloy laser wire-filled lap joints according to the present invention;

[0028] Figure 3 This is a schematic diagram of the sampling position of the lap joint according to the present invention;

[0029] Figure 4 This is a schematic diagram of the main structure of the lap joint used for shear strength testing according to the present invention;

[0030] Figure 5 It is a schematic diagram of the side view structure of the lap joint used for shear strength testing according to the present invention;

[0031] Figure 6 This is a schematic diagram of the lap joint welding structure of the present invention;

[0032] Figure 7 A schematic diagram of a test using a shear strength testing device according to the present invention;

[0033] Figure 8 It is a schematic diagram of the stress state of the lap joint according to the present invention;

[0034] Fig. 9It is a schematic diagram of the shear force test curve described in the present invention.

[0035] 1-jaw seat, 2-clamping cylinder, 3-jaw, 4-adjustment positioning plate, 5-left and right positioning plates, 6-upper and lower positioning plates, 7-positioning bolts, 8-lap joints, 9-weld seams, 10-line columns, 11-light emitting position, 12-light stopping position, 13-discarded part. DETAILED DESCRIPTION

[0036] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely explain the technical solutions in the embodiments of the present invention. It should be noted that the embodiments of the present invention and the features in the embodiments can be combined with each other without conflict, and the described embodiments are only part of the embodiments of the present invention, not all of the embodiments.

[0037] See also Figure 1-2 The present embodiment is described, a shear strength testing device for titanium alloy laser wire-filled lap joints, which includes a jaw seat 1, a clamping cylinder 2, a jaw 3, an adjustment positioning plate 4, a left and right positioning plate 5, an upper and lower positioning plate 6 and a wire column 10. There are two adjustment positioning plates 4, which are respectively arranged on both sides of the lap joint 8. There are two jaws 3, which are respectively arranged at both ends of the lap joint 8 and the adjustment positioning plate 4. The lap joint 8 is clamped with the adjustment positioning plate 4. The jaw 3 is arranged in the jaw seat 1, and the jaw 3 is connected to the clamping cylinder 2. The jaw 3 is clamped by the clamping cylinder 2. The clamping cylinder 2 passes through the jaw seat 1 and is connected to the wire column 10. The outer sides of the two adjustment positioning plates 4 are provided with left and right positioning plates 5, and the upper and lower sides of the adjustment positioning plates 4 are provided with upper and lower positioning plates 6.

[0038] The left and right positioning plates 5 are provided with positioning bolts 7, and the clamping cylinder 2 is provided with a fixing block, and the clamping cylinder 2 is connected to the jaws 3 through the fixing block. The jaw seat 1 can support and connect the clamping cylinder 2; the clamping cylinder 2 can clamp the jaws 3; the jaws 3 can clamp the lap joint 8 and the adjustment positioning plate 4 to eliminate the gap between the lap joint 8 and the adjustment positioning plate 4; the adjustment positioning plate 4 can be close to the lap joint and adjust the force of the lap joint so that it is on the central axis, thereby ensuring the accuracy of the shearing result measured by the test; the left and right positioning plates 5 can position and support the lap joint 8 on the left and right; the upper and lower positioning plates 6 can position and support the lap joint 8 on the upper and lower sides; the positioning bolts 7 can press and position the left and right positioning plates 5.

[0039] This embodiment is a testing method for a titanium alloy laser filler wire welded lap joint shear strength testing device, which includes the following steps:

[0040] Step 1: Laser wire welding is performed on titanium alloy plates of the same model and thickness. The thickness T of the titanium alloy plate is 5 mm. Two lap welds 9 are obtained by laser wire welding with a dual-beam and dual-wire feeding system at the same time to avoid poor weld fusion caused by thermal expansion deformation of the other side due to welding one side first, which will cause errors in the subsequent calculation of the weld area. During welding, the welding environment conditions are 20℃±5℃ and the relative humidity is between 20% and 50%. When sampling, such as Figure 3 As shown, the light-emitting position 11 and the light-stopping position 12 of the welded part are discarded, according to Figure 3-6 The lap joint 8 with a weld length l of 20 mm and a lap length e of 5 mm is obtained by processing;

[0041] Step 2: Use a vernier caliper to measure the lap joint 8 to obtain the weld width b and weld height a. The weld width b is 3-5 mm, and the weld height a is 3-5 mm. The relevant dimensions of the weld of the lap joint 8 are shown in the following table:

[0042] Table 1 Dimensions of lap joint welds in mm

[0043]

[0044] Step 3: Perform a shear strength test on the lap joint 8. The shear strength test should be performed within 48 hours after welding. Figure 1 , 2 As shown in FIG. 7 , the lap joint 8 is installed in the test device, and the lap joint 8 is pressed by adjusting the positioning plate 4 so that the adjustment positioning plate 4 and the lap joint 8 are subjected to the force as a whole at the central axis, and the adjustment positioning plate 4 and the lap joint 8 are clamped by the jaws 3, and the adjustment positioning plate 4 and the lap joint 8 are clamped by the jaw seat 1 and the clamping cylinder 2, and the adjustment positioning plate 4 and the lap joint 8 are clamped and positioned in the left and right directions by the left and right positioning plates 5 and the positioning bolts 7, and the adjustment positioning plate 4 and the lap joint 8 are clamped and positioned in the upper and lower directions by the upper and lower positioning plates 6, and the clamping of the lap joint 8 is completed;

[0045] Step 4: Use a universal testing machine to perform a shear strength test on the lap joint 8;

[0046] Step 5: Stretch the lap joint 8 and record the test force-beam displacement curve. The maximum test force on the curve is the shear force of the sample.

[0047] Step 6: The shear strength of the lap joint 8 is obtained by dividing the shear force F measured by the universal testing machine by the area of ​​the weld region of the lap joint 8. The shear strength of the lap joint 8 is calculated by the following formula:

[0048]

[0049] Where: τ is the shear strength, MPa; F 1 is the horizontal left shear force, kN; F 2 is the horizontal rightward shear force, kN; S 1 is the effective cross-sectional area of ​​the left lap weld, mm 2 ; S 2 is the effective cross-sectional area of ​​the right lap weld, mm 2 .

[0050] The test method of this embodiment processes multiple lap joints 8 of the same size, tests the multiple lap joints 8 to obtain multiple shear strengths of the multiple lap joints 8, calculates the average value of the multiple shear strength values, and retains two decimal places in the result. In order to eliminate contingency and reduce test errors, the shear force of at least two lap joints 8 should be tested in each group of tests.

[0051] In this embodiment, TC4 titanium alloy plate is used as the base material, Ti-6Al-4V titanium alloy welding wire with a diameter of Φ=1.2 mm is used as the filler metal, and double-beam laser wire welding technology is used to connect the lap joints. The welding process parameters are shown in Table 2.

[0052] Table 2 Welding process parameters

[0053]

[0054] After welding, the arc starting and arc ending parts were removed, and two lap joints 8 were prepared according to Table 3. Subsequently, the specimens were subjected to a tensile test with a loading rate of 3 mm / min.

[0055] Table 3 Sample size and welding point position (unit: mm)

[0056]

[0057] At room temperature within 48 hours after welding, the lap joint 8 is fixed on a test device, and the test device is clamped on a universal testing machine.

[0058] The specimen was stretched at a loading rate of 3 mm / min. The test force-beam displacement curves of the two lap joints 8 were recorded separately, such as Fig. 9 As shown. The shear forces of the two lap joints 8 are 6.58 kN and 6.47 kN respectively; the effective lap areas of the two lap joints 8 are: a×b=3.25×3.84 mm=12.48 mm 2 and a×b=3.11×3.75mm=11.66mm 2 , the shear strengths are 52.72MPa and 55.49MPa respectively, and the average shear strength is 54.10MPa.

[0059] The embodiments of the present invention disclosed above are only used to help illustrate the present invention. The embodiments do not describe all the details in detail, nor do they limit the invention to the specific implementation methods described. According to the content of this specification, many modifications and changes can be made. This specification selects and specifically describes these embodiments in order to better explain the principles and practical applications of the present invention, so that those skilled in the art can understand and use the present invention well.

Claims

1. A method for testing the shear strength of a titanium alloy laser-filled wire welded lap joint based on a titanium alloy laser-filled wire welded lap joint shear strength testing device, the testing device comprising a jaw seat (1), a clamping cylinder (2), a jaw (3), an adjustment positioning plate (4), left and right positioning plates (5), an upper and lower positioning plate (6) and a wire post (10), wherein the number of the adjustment positioning plates (4) is two, and the two adjustment positioning plates (4) are respectively arranged on both sides of the lap joint (8), the number of the jaws (3) is two, and the two jaws (3) are respectively arranged at the two ends of the lap joint (8) and the adjustment positioning plate (4), and the lap joint (8) is connected to the adjustment positioning plate (4). Clamping, the jaw (3) is arranged in the jaw seat (1), the jaw (3) is connected to the clamping cylinder (2), the jaw (3) is clamped by the clamping cylinder (2), the clamping cylinder (2) passes through the jaw seat (1) and is connected to the line column (10), a fixing block is arranged on the clamping cylinder (2), the clamping cylinder (2) is connected to the jaw (3) through the fixing block, the outer sides of the two adjustment positioning plates (4) are provided with left and right positioning plates (5), the upper and lower sides of the adjustment positioning plates (4) are provided with upper and lower positioning plates (6), and the left and right positioning plates (5) are provided with positioning bolts (7); the testing method comprises the following steps: Step 1: Laser wire-filling welding is performed on titanium alloy plates of the same model and thickness, and two lap welds (9) are obtained by laser wire-filling welding simultaneously with a dual-beam, dual-wire feeding system, and after discarding the light-emerging position (11) and the light-stopping position (12) of the welded piece, a lap joint (8) with a specified weld length l and lap length e is obtained; Step 2: measuring the lap joint (8) to obtain the weld width b and weld height a; Step 3: Perform a shear strength test on the lap joint (8), install the lap joint (8) in the test device, press the lap joint (8) by adjusting the positioning plate (4), so that the adjustment positioning plate (4) and the lap joint (8) are subjected to force on the central axis, clamp the adjustment positioning plate (4) and the lap joint (8) by the jaws (3), clamp the adjustment positioning plate (4) and the lap joint (8) by the jaw seat (1) and the clamping cylinder (2), clamp the adjustment positioning plate (4) and the lap joint (8) in the left and right directions by the left and right positioning plates (5) and the positioning bolts (7), and clamp the adjustment positioning plate (4) and the lap joint (8) in the upper and lower directions by the upper and lower positioning plates (6), and complete the clamping of the lap joint (8); Step 4: Use a universal testing machine to perform a shear strength test on the lap joint (8); Step 5: stretching the lap joint (8) and recording a test force-beam displacement curve, wherein the maximum test force on the curve is the shear force of the lap joint; Step 6: The shear strength of the lap joint (8) is obtained by dividing the shear force F measured by the universal testing machine by the area of ​​the weld region of the lap joint (8).

2. The testing method according to claim 1, characterized in that: The test method comprises processing a plurality of lap joints (8) of the same size, testing the plurality of lap joints (8) to obtain a plurality of shear strengths of the plurality of lap joints (8), calculating an average value of the plurality of shear strength values, and retaining two decimal places for the result.

3. The testing method according to claim 1, characterized in that: In step 1, the thickness T of the titanium alloy plate is 5 mm, the weld length l is 20 mm, and the overlap length e is 5 mm.

4. The testing method according to claim 1, characterized in that: In step 1, the welding environment condition is 20° C.±5° C., and the relative humidity is between 20% and 50%.

5. The testing method according to claim 1, characterized in that: In step 2, a vernier caliper is used to measure the lap joint (8), and the weld width b is 3-5 mm, and the weld height a is 3-5 mm.

6. The testing method according to claim 1, characterized in that: The shear strength test is carried out within 48 hours after welding.

7. The testing method according to claim 1, characterized in that: The shear strength of the lap joint (8) in step 6 is calculated by the following formula: Where: τ is the shear strength, MPa; F1 is the horizontal left shear force, kN; F2 is the horizontal right shear force, kN; S1 is the effective cross-sectional area of ​​the left lap weld, mm 2 ; S2 is the effective cross-sectional area of ​​the right lap weld, mm 2 .

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