A method for testing the tensile strength of a weld of a variable-thickness dissimilar material butt joint

Abstract

The present application is a kind of butt joint welding tensile strength test method of variable thickness dissimilar material, aiming at the welding tensile strength test of the product formed by splicing two variable thickness parts made of dissimilar materials, the two kinds of dissimilar materials of the product are metal plates with welding length L and thickness gradually changing from maximum d max to minimum d min , comprising the following steps: step one, taking two kinds of materials same as the two kinds of dissimilar materials spliced in the product to make a part (1) and a part (2) with the same length L and the same gradually changing thickness d of the welding of the two parts spliced in the product; the present application is a new detection method for welded products, which can reflect the quality of the product itself, save money and labor, and provide a brand new method for the detection of welding strength of similar products.

Description

Technical Field

[0001] This invention relates to a method for testing the tensile strength of welds, and more particularly to a method for testing the tensile strength of welds in butt joints of dissimilar materials with varying thickness. Background Technology

[0002] To meet structural and performance requirements, a certain product is constructed by welding two parts made of dissimilar materials together. The connection is a variable-thickness butt weld joint, with the thickness varying uniformly and linearly from the thinner end to the thicker end. To achieve full weld penetration and control welding deformation, the welding heat input also varies uniformly and linearly from the thinner end to the thicker end.

[0003] Before welding the final product, test specimens must be welded and tensile strength tested to verify the feasibility of the process. Within the range from the thinnest to the thickest, different thickness values ​​are selected to design butt joint specimens of equal thickness. Test specimens are then welded using corresponding fixed heat input values, and the tensile strength of the weld is tested. However, this method cannot fully verify the tensile strength of welds for butt joints with linearly varying thicknesses when using linearly varying heat input.

[0004] Therefore, a method and specimen for testing the tensile strength of welds in butt joints of dissimilar materials with varying thickness were designed. This method achieves linearly varying heat input to test the tensile strength of welds in butt joints with linearly varying thicknesses, thus fully verifying the tensile strength of the welds. Summary of the Invention

[0005] The purpose of this invention is to provide a method for testing the tensile strength of welds in butt joints of dissimilar materials with varying thickness. This method enables the testing of the tensile strength of welds in butt joints with linearly varying thicknesses by using linearly varying heat input, thereby verifying the tensile strength of the welds.

[0006] A method for testing the tensile strength of weld seams in butt joints of dissimilar materials with varying thicknesses is provided, specifically for testing the tensile strength of weld seams in products assembled from two dissimilar materials with varying thicknesses. The method assumes that both dissimilar materials in the product have weld seam lengths of L and thicknesses ranging from a maximum of d. max Linear change to minimum d min The metal plate includes the following steps:

[0007] Step 1: Take two materials identical to the two dissimilar materials to be welded to the product, and fabricate two parts, a1 and b2, with the same weld length L and the same gradient thickness d as the two components to be welded to the product. Part a1 has a width of h1, and part b2 has a width of h2. Align the weld joints of part a1 and part b2. That is, part a1 has the same thickness as one of the materials in the final product, starting from the maximum d. max Linear change to minimum d min The metal sheet, part 2, is made of another material with the same thickness as the main product, with a maximum thickness of d. max Linear change to minimum dmin The length L of the metal plates, parts a1 and b2, is equal to the length L of the mating part of the final product. The maximum thickness d of parts a1 and b2 is... max The maximum thickness of the parts that mate with the final product is equal, and the minimum thickness d of parts a1 and b2 is equal. min The minimum thickness of the part that interfaces with the final product is equal.

[0008] Step 2: Place part a1 and part b2 at the point of minimum thickness d. min Autofusion welding is performed starting at point 3, following the process specifications for linear heat input variation as defined during product welding, to form welded specimen 3; assuming the minimum thickness d at the start of linear heat input variation. min The power at the location is W min Maximum thickness d max The power at the location is W max ;

[0009] Step 3: Cut n tensile test specimens 4 from the welded specimen 3 formed by welding parts a1 and b2 together, with the cutting line perpendicular to the welding line. The n tensile test specimens 4 are evenly distributed on the welded specimen 3; n = 5 to 10 specimens, numbered 1# to n#. The length of the tensile test specimen 4 is h1 + h2, and the width t = 2mm to 10mm. Number 1# represents the thinnest position of the welded specimen 3, and number n# represents the thickest position.

[0010] Step 4: Perform tensile tests on n tensile specimens 4. Let the tensile forces of the n tensile specimens 4 be F1, F2, ..., F... n The tensile strength of each tensile specimen 4 is calculated using the formula: σ = F / A; where F is the tensile force and A is the cross-sectional area at the weld of the tensile specimen 4, thus obtaining the tensile strength of n tensile specimens 4.

[0011] Step 5: If the tensile strength of all n tensile specimens 4 meets the specified value requirement, and the arithmetic mean of the tensile strength of all tensile specimens 4 is taken as the standard value, and the tensile strength test data of each tensile specimen 4 is greater than 75% of the standard value, then the welded specimen 3 is qualified; proceed to step 8; if the test fails; proceed to the next step.

[0012] Step 6: If the above test fails, adjust the minimum thickness d of the welding test piece 3. min Power W at the location min and / or maximum thickness d max Power W at the location max Then proceed to step one and repeat the experiment;

[0013] Step 7: If modifying the welding power parameter W min or Wmax After the numerical test was passed, the modified welding power parameter W was applied. min or W max The values ​​are used in the subsequent welding of the product;

[0014] Step 8: This experiment is now complete.

[0015] To meet higher product quality requirements, the welded specimen 3 is considered qualified only if the tensile strength test data of each tensile specimen 4 in step five is greater than 80% of the standard value.

[0016] The width h1 of part a1 is in the range of 60mm≤h1≤100mm, and the width h2 of part b2 is in the range of 60mm≤h2≤100mm.

[0017] Beneficial effects of the invention

[0018] This invention reproduces the product welding process by manufacturing test pieces (parts a1 and b2) and welding them together. The weld strength of the weld seam is obtained by cutting and measuring the welded test piece (3) to ensure product quality. If the weld strength is insufficient, the welding parameters are adjusted promptly to improve product quality.

[0019] This invention uses the manufacturing of parts a1 and b2 to simulate the product welding process. This method not only ensures product quality but also allows for the modification of welding parameters to improve product quality when it is insufficient. The method of this invention significantly reduces costs compared to directly measuring the tensile strength of the product and avoids the hassle of cutting the product for measurement (because the product has other connected parts and a complex shape, making it difficult to cut specimens with suitable structural dimensions for tensile strength testing).

[0020] This invention is a new testing method for welded products. It can reflect the quality of the product itself, and it is cost-effective and labor-saving, providing a brand-new method for testing the weld strength of similar products. Attached Figure Description

[0021] Figure 1 A schematic diagram of the structure of the welding specimen 3 of this invention.

[0022] (a) Front view of the welding specimen 3 of the present invention;

[0023] (b) Left view of the welding specimen 3 of the present invention.

[0024] In the diagram: 1 is part a, 2 is part b, 3 is a welding specimen, and 4 is a tensile specimen. Detailed Implementation

[0025] A method for testing the tensile strength of weld seams in butt joints of dissimilar materials with varying thickness, such as... Figure 1As shown, part 1 is made of the same material as the final product, with a thickness of up to d. max Linear change to minimum d min The metal sheet, part 2, is made of another material with the same thickness as the main product, with a maximum thickness of d. max Linear change to minimum d min The metal plates, part a1 and part b2, have widths L equal to the width of the mating area of ​​the final product, and the maximum thickness d of part a1 and part b2 is... max The maximum thickness of the parts that mate with the final product is equal, and the minimum thickness d of parts a1 and b2 is equal. min The minimum thickness of the parts mating with the final product should be equal. Part a1 has a width h1 of 60mm–100mm, and part b2 has a width h2 of 60mm–100mm. Part a1 and part b2 should be welded together according to the specified linear heat input process to form a welded test piece 3. The post-weld length L should ideally be 120mm–300mm. max A thickness of 10mm to 30mm is recommended. min A thickness of 2mm to 10mm is recommended.

[0026] Tensile test specimens 4 are cut from welded specimen 3 for tensile strength testing. The number of tensile test specimens 4 is n, n=5 to 10, numbered 1# to n#, with a length of h1+h2 and a width t=2mm to 10mm. The cutting positions of tensile test specimens 4 must cover both end faces, that is, 1# and n# must include the thickest and thinnest positions, and the cutting positions should be as evenly distributed as possible.

[0027] Tensile tests were conducted on n tensile specimens 4, and the tensile forces of each tensile specimen 4 were F1, F2, ..., F... n The cross-sectional area of ​​each tensile specimen 4 is A. n =(d 2n-1 +d 2n ) × t / 2. Tensile strength σ of each tensile specimen 4 b = F n / A n .

[0028] The tensile strength of each tensile specimen 4 must meet the specified value requirement, and the arithmetic mean of the tensile strength of all tensile specimens 4 shall be taken as the standard value. The test data of each specimen shall be not less than 75% (or 80%) of the standard value to be considered as qualified.

[0029] The above description is merely an overview of the technical solution of this patent. In order to better understand the technical means of this patent, it can be implemented according to the contents of the specification. Furthermore, in order to make the above and other objects, features and advantages of this invention more apparent and understandable, a detailed description is provided in conjunction with the foregoing drawings.

[0030] Example 1:

[0031] The specific method of this invention is as follows:

[0032] Step 1: Make part 1 (a) out of titanium alloy and part 2 (b) out of niobium alloy. Both part 1 and part 2 are rectangular metal plates with a length L of 200mm, a width h1 of 80mm, a width h2 of 80mm, and a thickness d of 6mm that gradually decreases to 20mm. Align the welding parts of the long sides L of part 1 and part 2.

[0033] Step 2: Place part a1 and part b2 at the point of minimum thickness d. min Autofusion welding is performed starting at point 3, following the process specifications for linear heat input variation as defined during product welding, to form welded specimen 3; assuming the minimum thickness d at the start of linear heat input variation. min Power W min It has a power rating of 2000 watts and a maximum thickness of d. max Power W max It is 8000 watts;

[0034] Step 3: Cut 5 tensile test specimens 4 from the welded specimen 3 formed by welding parts a1 and b2 together, with the cutting line perpendicular to the welding line. The 5 tensile test specimens 4 are evenly distributed on the welded specimen 3. The length of the tensile test specimen 4 is h1+h2, and the width of the tensile test specimen 4 is t=6mm. The number 1# is the thinnest position of the welded specimen 3, and the number 5# is the thickest position of the welded specimen 3.

[0035] Step 4: Tensile strength tests were conducted on the five tensile specimens 4. The tensile strengths of the five tensile specimens 4 were measured to be 418 MPa, 428 MPa, 423 MPa, 425 MPa and 419 MPa, respectively.

[0036] Step 5: The tensile strength of all 5 tensile specimens 4 meets the specified value of 350MPa, and the tensile strength test data of each tensile specimen 4 is greater than 75% of the standard value. Therefore, the welded specimen 3 is qualified for the test.

[0037] Step Six: This test is complete. This indicates that the product of this invention meets the requirements and is a qualified product.

Claims

1. A method for testing the tensile strength of weld seams in butt joints of dissimilar materials with varying thicknesses, specifically for testing the tensile strength of weld seams in products assembled from two dissimilar materials with varying thicknesses. The method assumes that both dissimilar materials in the product have weld seam lengths of L and thicknesses ranging from a maximum of d. max Linear change to minimum d min The metal plate includes the following steps: Step 1: Take two materials identical to the two dissimilar materials to be welded to the product, and make two parts, a (1) and b (2), with the same weld length L and the same gradient thickness d as the two parts to be welded to the product. The width of part a (1) is h1, and the width of part b (2) is h2. Align the welding parts of part a (1) and part b (2). That is, part a (1) is the same material as the final product with a thickness starting from the maximum d. max Linear change to minimum d min The metal plate, part b (2) is of the same thickness as the other material in the formal product, with a maximum thickness of d. max Linear change to minimum d min The length L of the metal plate, part a (1) and part b (2) is equal to the length L of the mating part of the final product, and the maximum thickness d of part a (1) and part b (2) is... max The maximum thickness of the parts that mate with the final product is equal, and the minimum thickness d of parts a (1) and b (2) is equal. min The minimum thickness of the part that interfaces with the final product is equal. Step 2: Place part a (1) and part b (2) from the point where the thickness is smallest, d. min Autofusion welding is performed at the point where the heat input changes linearly according to the process specifications for product welding, forming a welded specimen (3); assuming the minimum thickness d at the start of the linear change in heat input. min The power at the location is W min Maximum thickness d max The power at the location is W max ; Step 3: Cut n tensile test pieces (4) from the welded test piece (3) formed by welding part (1) and part (2) together, wherein the cutting line is perpendicular to the welding line. Cut n tensile test pieces (4) evenly distributed on the welded test piece (3); n = 5 to 10, numbered 1# to n#. The length of the tensile test piece (4) is h1 + h2, and the width of the tensile test piece (4) is t = 2 mm to 10 mm. The number 1# is the thinnest position of the welded test piece (3), and the number n# is the thickest position of the welded test piece (3). Step 4: Perform tensile tests on n tensile specimens (4). Let the tensile forces of the n tensile specimens (4) be F1, F2, ..., F... n The tensile strength of each tensile specimen (4) is calculated using the formula: σ = F / A; F is the tensile force, and A is the cross-sectional area of ​​the weld of the tensile specimen (4) to obtain the tensile strength of n tensile specimens (4); Step 5: If the tensile strength of all n tensile specimens (4) meets the specified value requirement, and the arithmetic mean of the tensile strength of all tensile specimens (4) is taken as the standard value, and the tensile strength test data of each tensile specimen (4) is greater than 75% of the standard value, then the welded specimen (3) is qualified; proceed to step 8; if the test is unqualified; proceed to the next step; Step 6: If the above test fails, adjust the minimum thickness d of the welding test piece (3). min Power W at the location min and / or maximum thickness d max Power W at the location max Then proceed to step one and repeat the experiment; Step 7: If modifying the welding power parameter W min or W max After the numerical test was passed, the modified welding power parameter W was applied. min or W max The values ​​are used in the subsequent welding of the product; Step 8: This experiment is now complete.

2. The method for testing the tensile strength of weld seams in butt joints of dissimilar materials with varying thickness according to claim 1, characterized in that, To meet higher product quality requirements, the welded specimen (3) is considered qualified only when the tensile strength test data of each tensile specimen (4) in step five is greater than 80% of the standard value.

3. The method for testing the tensile strength of weld seams in butt joints of dissimilar materials with varying thickness according to claim 1, characterized in that, The width h1 of part a (1) is in the range of 60mm≤h1≤100mm, and the width h2 of part b (2) is in the range of 60mm≤h2≤100mm.

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