Welding zone strength testing method

Abstract

The present invention provides a welding zone strength detection method, which belongs to the technical field of non-destructive testing. The welding zone strength detection method comprises: performing surface pretreatment on a sample plate after welding. The sample plate after pretreatment is used as a plate to be tested, and a hardness test is performed on the weld to determine the hardness value. A plurality of tensile test pieces and a plurality of spectral test pieces are cut out of the plate to be tested. A tensile test is performed on the tensile test piece to determine the tensile strength value of the weld metal. A spectral analysis is performed on the spectral test piece to determine the element content value. The tensile strength, element content and hardness curve are determined from the tensile strength value, element content value and hardness value. The hardness value and element content value at the weld of the target steel are measured, and the tensile strength target value at the weld of the target steel is deduced from the tensile strength, element content and hardness curve. The welding zone strength detection method provided by the present invention avoids damage to the original structure and provides relatively accurate tensile strength information.

Description

Technical Field

[0001] The invention belongs to the technical field of nondestructive testing, and more specifically, relates to a welding zone strength testing method. Background Art

[0002] Construction project quality inspection agencies undertake a large number of steel structure engineering inspection and appraisal tasks in their daily work. In the actual inspection process, they often encounter situations where they need to inspect the tensile strength of component steel and welds. At present, the main method used for inspection and appraisal of steel types, steel strength, weld strength, etc. of existing steel structure buildings is to conduct chemical composition analysis and mechanical property testing after on-site cutting and sampling, which will cause local damage to the original steel structure. Summary of the invention

[0003] The purpose of the present invention is to provide a welding zone strength detection method, aiming to solve the problem that the original structure will be damaged when testing the strength of the steel weld.

[0004] To achieve the above object, the technical solution adopted by the present invention is: to provide a welding zone strength detection method, comprising:

[0005] Welding the sample plates and performing surface pretreatment on the welded sample plates;

[0006] The sample plate after pretreatment is used as the plate to be tested, and the hardness of the weld of the plate to be tested is tested to determine the hardness value;

[0007] Cutting a plurality of tensile test pieces and a plurality of spectral test pieces from the plate to be tested;

[0008] Performing a tensile test on the tensile test piece to determine the tensile strength value of the weld metal;

[0009] Performing spectral analysis on the spectral specimen to determine the element content value;

[0010] Determining a tensile strength, element content and hardness curve from the tensile strength value, the element content value and the hardness value;

[0011] The hardness value and element content value at the target steel weld are measured, and the target tensile strength value at the target steel weld is deduced based on the tensile strength, element content and hardness curve.

[0012] As another embodiment of the present application, the welding of the sample plate and the surface pretreatment of the welded sample plate include:

[0013] The sample plate is welded after a V-shaped groove is formed;

[0014] The sample plate is polished after welding.

[0015] As another embodiment of the present application, before taking the pre-treated sample plate as the plate to be tested and performing hardness test on the weld of the plate to be tested, the process includes:

[0016] Measuring the surface roughness values ​​of different areas of the sample plate after grinding, and adding and averaging a plurality of the roughness values ​​to determine the average roughness value;

[0017] When the roughness average value is less than the preset standard, a subsequent test is performed.

[0018] As another embodiment of the present application, the sample plate after pretreatment is used as the plate to be tested, and the hardness test is performed on the weld of the plate to be tested, and the hardness value is determined, including:

[0019] The sample plate which is pretreated to meet the preset standard is used as the plate to be tested;

[0020] The surface hardness of the weld of the plate to be tested is tested using a calibrated Leeb hardness tester to determine the hardness value.

[0021] As another embodiment of the present application, cutting the sheet to be tested into a plurality of tensile test pieces and a plurality of spectral test pieces comprises:

[0022] Evenly drawing a plurality of groups of stretching area lines and spectral area lines on the plate to be tested, wherein both the stretching area lines and the spectral area lines pass through the welding area of ​​the plate to be tested;

[0023] According to the stretching region line and the spectral region line, the plate to be tested is respectively cut out to obtain the plate within the stretching region line and the spectral region line, and the plates are respectively used as the stretching test piece and the spectral test piece.

[0024] As another embodiment of the present application, after performing a tensile test on the tensile specimen to determine the tensile strength value of the weld metal, the method includes:

[0025] A hardness and tensile strength curve is drawn by combining the tensile strength value with the hardness value corresponding to each tensile test piece.

[0026] As another embodiment of the present application, the drawing of a hardness and tensile strength curve by combining the tensile strength value with the hardness value corresponding to each tensile test piece includes:

[0027] Marking first coordinate points corresponding to the tensile strength values ​​and the hardness values ​​of a plurality of the tensile test pieces in a first coordinate system;

[0028] The hardness and tensile strength curve is fitted according to the plurality of the first coordinate points.

[0029] As another embodiment of the present application, after performing spectral analysis on the spectral specimen to determine the content value of each element and combining it with the tensile strength value, the method includes:

[0030] A tensile strength and element content curve is drawn by combining the element content value and the tensile strength value corresponding to each tensile test piece.

[0031] As another embodiment of the present application, the tensile strength and element content curve is drawn by combining the element content value and the tensile strength value corresponding to each tensile specimen, including:

[0032] Marking a plurality of second coordinate points corresponding to the tensile strength values ​​and the element content values ​​of the tensile test pieces in a second coordinate system;

[0033] The tensile strength and element content curve is fitted according to the plurality of the second coordinate points.

[0034] As another embodiment of the present application, the hardness value and element content value at the target steel weld are determined, and the target tensile strength value at the target steel weld is calculated based on the tensile strength, element content and hardness curve, including:

[0035] Respectively measuring the hardness value and element content value at the weld of the target steel material;

[0036] Determining the tensile strength, element content and hardness curve of the sample plate corresponding to the target steel weld;

[0037] The tensile strength target value is determined according to the hardness value and element content value at the weld of the target steel material in the tensile strength, element content and hardness curve.

[0038] The welding zone strength detection method provided by the present invention has the beneficial effect that, compared with the prior art, the welding zone strength detection method of the present invention firstly welds the sample plate, and performs surface pretreatment on the welded sample plate. The sample plate after pretreatment is used as the plate to be tested, and the weld of the plate to be tested is subjected to hardness test to determine the hardness value. A plurality of tensile test pieces and a plurality of spectral test pieces are cut out from the plate to be tested; a tensile test is performed on the tensile test piece to determine the tensile strength value of the weld metal; a spectral analysis is performed on the spectral test piece to determine the element content value. The tensile strength, element content and hardness curve are determined from the tensile strength value, element content value and hardness value; the hardness value and element content value at the weld of the target steel are measured, and the tensile strength target value at the weld of the target steel is deduced from the tensile strength, element content and hardness curve. In the detection method, the detection accuracy can be improved by pretreatment of the surface of the sample plate, and the accuracy of the measured value can be ensured. By selecting a plurality of tensile test pieces and spectral test pieces from the plate to be tested, the material information of each area of ​​the plate to be tested can be more realistically reflected. The tensile strength, element content and hardness curve determined by the strength value, element content value and hardness value can reflect the variable relationship between the three. The target tensile strength value at the weld of the target steel can be determined by measuring the hardness value and element value at the weld of the target steel on site. This method does not require cutting and sampling of the steel structure in the building on site, avoiding damage to the original structure, and can more accurately determine the tensile strength of the steel. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 A flow chart of a welding zone strength detection method provided by an embodiment of the present invention;

[0040] Figure 2 A graph showing the relationship between hardness and tensile strength provided by an embodiment of the present invention;

[0041] Figure 3 A graph showing the relationship between carbon content and tensile strength provided in an embodiment of the present invention;

[0042] Figure 4 A graph showing the relationship between silicon content and tensile strength provided in an embodiment of the present invention;

[0043] Figure 5 A graph showing the relationship between manganese content and tensile strength provided in an embodiment of the present invention;

[0044] Figure 6 A graph showing the relationship between phosphorus content and tensile strength provided in an embodiment of the present invention;

[0045] Figure 7 A graph showing the relationship between sulfur content and tensile strength provided in an embodiment of the present invention;

[0046] Figure 8A comparison chart of the estimated tensile strength and the measured tensile strength at different hardnesses at the target steel weld provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0047] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0048] See also Figure 1 The welding zone strength detection method provided by the present invention is now described. The welding zone strength detection method comprises: welding a sample plate, and performing surface pretreatment on the welded sample plate.

[0049] The sample plate after pretreatment is used as the plate to be tested, and the hardness test is carried out on the weld of the plate to be tested to determine the hardness value.

[0050] A plurality of tensile test pieces and a plurality of spectral test pieces are cut out from the plate to be tested.

[0051] A tensile test is performed on the tensile specimen to determine the tensile strength value of the weld metal.

[0052] The spectrum specimen is subjected to spectrum analysis to determine the content value of each element.

[0053] A tensile strength, element content and hardness curve is determined from the hardness and tensile strength curve and the tensile strength and element content curve.

[0054] The hardness value and element content value at the target steel weld are measured, and the target tensile strength value at the target steel weld is selected on the tensile strength, element content and hardness curve.

[0055] The welding zone strength detection method provided by the present invention has the beneficial effect that, compared with the prior art, the welding zone strength detection method of the present invention firstly welds the sample plate, and performs surface pretreatment on the welded sample plate. The sample plate after pretreatment is used as the plate to be tested, and the weld of the plate to be tested is subjected to hardness test to determine the hardness value. A plurality of tensile test pieces and a plurality of spectral test pieces are cut out from the plate to be tested; a tensile test is performed on the tensile test piece to determine the tensile strength value of the weld metal; a spectral analysis is performed on the spectral test piece to determine the element content value. The tensile strength, element content and hardness curve are determined from the tensile strength value, element content value and hardness value; the hardness value and element content value at the weld of the target steel are measured, and the tensile strength target value at the weld of the target steel is deduced from the tensile strength, element content and hardness curve. In the detection method, the detection accuracy can be improved by pretreatment of the surface of the sample plate, and the accuracy of the measured value can be ensured. By selecting a plurality of tensile test pieces and spectral test pieces from the plate to be tested, the material information of each area of ​​the plate to be tested can be more realistically reflected. The tensile strength, element content and hardness curve determined by the strength value, element content value and hardness value can reflect the variable relationship between the three. The target tensile strength value at the weld of the target steel can be determined by measuring the hardness value and element value at the weld of the target steel on site. This method does not require cutting and sampling of the steel structure in the building on site, avoiding damage to the original structure, and can more accurately determine the tensile strength of the steel.

[0056] As a specific implementation of the welding zone strength detection method provided by the present invention, please refer to Figure 3 The welding of the sample plate and the surface pretreatment of the welded sample plate include:

[0057] The sample plate is welded after a V-shaped groove is formed.

[0058] The sample plate is polished after welding.

[0059] In the present invention, each group of sample plates uses the same grade of steel plates and uses a V-shaped groove for automatic welding, and the weld width is controlled to be no less than 30 mm, so as to facilitate the study of weld metal. In addition, the surface of the steel plate base material and the weld on the sample plate is polished, thereby ensuring the accuracy of subsequent tests and the reliability of data.

[0060] As a specific implementation of the welding zone strength detection method provided by the present invention, please refer to Figure 1 , before taking the pre-treated sample plate as the plate to be tested and conducting hardness test on the weld of the plate to be tested, the following steps are included:

[0061] The surface roughness values ​​of different areas of the sample plate after grinding are measured, and a plurality of the roughness values ​​are summed and averaged to determine the average roughness value.

[0062] When the roughness average value is less than the preset standard, a subsequent test is performed.

[0063] In the present invention, a roughness meter is used to measure the roughness of the polished surface. Each measurement should not be less than 5 points, and the average value is taken. The reading is accurate to 0.01μm, and the test surface roughness should not be greater than 1.6μm before subsequent tests can be carried out. The roughness value of the surface of the sample plate can be accurately measured by the roughness meter. By measuring the roughness values ​​in different areas, summing and averaging, the inaccuracy of the data can be effectively avoided, thereby truly reflecting the current degree of polishing.

[0064] As a specific implementation of the welding zone strength detection method provided by the present invention, the sample plate after pretreatment is used as the plate to be tested, and the weld of the plate to be tested is tested for hardness, and the hardness value is determined, including:

[0065] The sample plates that have been pretreated to meet the preset standards are used as the plates to be tested.

[0066] The surface hardness of the weld of the plate to be tested is tested using a calibrated Leeb hardness tester to determine the hardness value.

[0067] In the present invention, the surface hardness test of the steel plate base material and the weld metal is carried out using a calibrated Leeb hardness tester. The hardness test is carried out on the whole uncut steel plate, while the tensile test piece is machined after the steel plate is cut. The tensile test piece that meets the tensile test size requirements is no longer suitable for hardness testing. Therefore, the hardness test is carried out first, and then the cutting and tensile strength test are carried out.

[0068] As a specific implementation of the welding zone strength detection method provided by the present invention, cutting the plate to be tested into a plurality of tensile test pieces and a plurality of spectral test pieces comprises:

[0069] A plurality of groups of stretching area lines and spectral area lines are evenly drawn on the plate to be tested, and both the stretching area lines and the spectral area lines pass through the welding area of ​​the plate to be tested.

[0070] According to the stretching region line and the spectral region line, the plate to be tested is respectively cut out to obtain the plate within the stretching region line and the spectral region line, and the plates are respectively used as the stretching test piece and the spectral test piece.

[0071] In the present invention, a plurality of stretching area lines and spectral area lines can be pre-delineated on the plate to be tested, and the stretching area lines and spectral area lines can be set in groups, and the stretching area lines and spectral area lines should be uniformly distributed in different areas of the plate to be tested, thereby ensuring the reliability of the data. The plate located at the area line is cut off by a cutting machine, the tensile specimen is deburred, and the spectral specimen is pre-processed before spectral analysis, thereby improving the accuracy of spectral analysis.

[0072] As a specific implementation of the welding zone strength detection method provided by the present invention, please refer to Figure 2 , after performing a tensile test on the tensile specimen to determine the tensile strength value of the weld metal, the method comprises:

[0073] A hardness and tensile strength curve is drawn by combining the tensile strength value with the hardness value corresponding to each tensile test piece.

[0074] In the present invention, the horizontal coordinate of the hardness and tensile strength curve can be the hardness value, and the vertical coordinate can be the strength value. Each point in the coordinate corresponds to the hardness value of a different position of the plate and the strength value of the same position. The closest curve is determined by multiple points, which is the hardness and tensile strength curve.

[0075] As a specific implementation of the welding zone strength detection method provided by the present invention, please refer to Figure 2 , the step of drawing a hardness and tensile strength curve by combining the tensile strength value with the hardness value corresponding to each tensile test piece comprises:

[0076] A plurality of first coordinate points corresponding to the tensile strength values ​​and the hardness values ​​of the tensile test pieces are marked in a first coordinate system.

[0077] The hardness and tensile strength curve is fitted according to the plurality of the first coordinate points.

[0078] In the present invention, the hardness and tensile strength curve in the coordinate system can reflect the change in strength values ​​corresponding to different hardness values. By determining the curve closest to all points, the hardness and tensile strength curve is close to a straight line, and it can be seen that the hardness value and the tensile strength value show a linear change.

[0079] As a specific implementation of the welding zone strength detection method provided by the present invention, please refer to Figures 3 to 7 , after performing spectral analysis on the spectral specimen to determine the content value of each element, the method further comprises:

[0080] A tensile strength and element content curve is drawn by combining the element content value and the tensile strength value corresponding to each tensile test piece.

[0081] In the present invention, the elements measured by the spectrum are: carbon, silicon, manganese, phosphorus and sulfur. Thus, the relationship between the change of each element content and the tensile strength value is truly reflected. Since the material of the detected plate is different, the influence coefficient of each element is different, and the steel material that is the same or similar to that on site should be selected for testing.

[0082] As a specific implementation of the welding zone strength detection method provided by the present invention, please refer to Figures 3 to 7 , the step of drawing a tensile strength versus element content curve by combining the element content value with the tensile strength value corresponding to each tensile test piece comprises:

[0083] A plurality of second coordinate points corresponding to the tensile strength values ​​and the element content values ​​of the tensile test pieces are marked in a second coordinate system.

[0084] The tensile strength and element content curve is fitted according to the plurality of the second coordinate points.

[0085] In the present invention, each element corresponds to a coordinate graph, in which the horizontal axis can be the content of the element and the vertical axis is the tensile strength value. The analyzed content value and the corresponding tensile strength value of the spectrum measured at each test point are marked on the second coordinate system, and the closest curve is determined to be fitted, thereby reflecting the change in tensile strength corresponding to different contents.

[0086] As a specific implementation of the welding zone strength detection method provided by the present invention, please refer to Figure 8 , the hardness value and element content value at the target steel weld are determined, and the target tensile strength value at the target steel weld is selected on the tensile strength, element content and hardness curve, including:

[0087] The hardness value and element content value at the weld of the target steel are measured respectively.

[0088] The tensile strength, element content and hardness curve of the sample plate corresponding to the target steel weld are determined.

[0089] The tensile strength target value is determined according to the hardness value and element content value at the weld of the target steel material in the tensile strength, element content and hardness curve.

[0090] In the present invention, SPSS is used as a tool for data analysis and drawing. SPSS uses a method similar to EXCEL tables to input and manage data. The data interface is relatively universal and can easily read data from other databases. Its statistical process includes commonly used and relatively mature statistical processes, which can fully meet the work needs of non-statistical professionals. The basic functions of SPSS include data management, statistical analysis, chart analysis, output management, etc. The SPSS statistical analysis process includes several major categories such as descriptive statistics, mean comparison, general linear model, correlation analysis, regression analysis, log-linear model, cluster analysis, data simplification, survival analysis, time series analysis, and multiple responses. Each category is divided into several statistical processes. For example, regression analysis is divided into linear regression analysis, curve estimation, Logistic regression, Probit regression, weighted estimation, two-stage least squares method, nonlinear regression and other statistical processes, and each process allows users to select different methods and parameters. SPSS also has a special drawing system that can draw various graphics based on data. Taking the present invention as an example, the obtained comprehensive curve of the relationship between the Leeb hardness-element content-tensile strength of the weld metal can be expressed as:

[0091] σ f =aHLD+bC+cSi+dMn+eP+fS

[0092] Where: HLD is the hardness value, C is the carbon content, Si is the silicon content, Mn is the manganese content, P is the phosphorus content, S is the sulfur content, a, b, c, d, e and f represent the coefficients corresponding to the corresponding values ​​respectively;

[0093] By measuring the hardness value of the target steel weld and the content value of the elements after spectral analysis, the values ​​of a, b, c, d, e and f obtained for each steel are different. Substituting the measured results on site into the above formula, the tensile strength value of the target steel weld can be inferred. This process does not require the destruction of the original structure, and non-destructive testing is achieved. The relationship between the Leeb hardness and the tensile strength of the steel plate base material is verified, and by adding the process of chemical composition analysis of the steel plate base material, the Leeb hardness of the steel plate base material and the content data of each element of carbon, silicon, manganese, phosphorus and sulfur are obtained. The strength measurement formula is obtained by comprehensive regression fitting, and the tensile strength of the steel plate base material can be non-destructively estimated with higher accuracy. Then, through a large number of experiments, this method is applied to the non-destructive testing of the tensile strength of weld metal with high accuracy.

[0094] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for detecting the strength of a welding zone, the characteristics of which include: Welding the sample plates and performing surface pretreatment on the welded sample plates; The sample plate after pretreatment is used as the plate to be tested, and the hardness of the weld of the plate to be tested is tested to determine the hardness value; Cutting a plurality of tensile test pieces and a plurality of spectral test pieces from the plate to be tested; Performing a tensile test on the tensile test piece to determine the tensile strength value of the weld metal; Performing spectral analysis on the spectral specimen to determine the element content value; Determining a tensile strength, element content and hardness curve from the tensile strength value, the element content value and the hardness value; The hardness value and element content value at the target steel weld are measured, and the target tensile strength value at the target steel weld is deduced based on the tensile strength, element content and hardness curve.

2. The welding zone strength detection method according to claim 1, wherein the welding of the sample plate and the surface pretreatment of the welded sample plate include: The sample plate is welded after a V-shaped groove is formed; The sample plate is polished after welding.

3. The welding zone strength detection method according to claim 2 is characterized in that before the pre-treated sample plate is used as the plate to be tested and the hardness test of the weld of the plate to be tested is performed, the method comprises: Measuring the surface roughness values ​​of different areas of the sample plate after grinding, and adding and averaging a plurality of the roughness values ​​to determine the average roughness value; When the roughness average value is less than the preset standard, a subsequent test is performed.

4. The welding zone strength detection method according to claim 1, wherein the sample plate after pretreatment is used as the plate to be tested, and the hardness test is performed on the weld of the plate to be tested, and the hardness value is determined to include: The sample plate which is pretreated to meet the preset standard is used as the plate to be tested; The surface hardness of the weld of the plate to be tested is tested using a calibrated Leeb hardness tester to determine the hardness value.

5. The welding zone strength detection method according to claim 1, wherein the step of cutting the plate to be tested into a plurality of tensile test pieces and a plurality of spectral test pieces comprises: Evenly drawing a plurality of groups of stretching area lines and spectral area lines on the plate to be tested, wherein both the stretching area lines and the spectral area lines pass through the welding area of ​​the plate to be tested; According to the stretching region line and the spectral region line, the plate to be tested is respectively cut out to obtain the plate within the stretching region line and the spectral region line, and the plates are respectively used as the stretching test piece and the spectral test piece.

6. The welding zone strength detection method according to claim 1, characterized in that after the tensile test piece is subjected to a tensile test to determine the tensile strength value of the weld metal, the method comprises: A hardness and tensile strength curve is drawn by combining the tensile strength value with the hardness value corresponding to each tensile test piece.

7. The welding zone strength detection method according to claim 6, wherein the step of drawing a hardness and tensile strength curve by combining the tensile strength value with the hardness value corresponding to each tensile test piece comprises: Marking first coordinate points corresponding to the tensile strength values ​​and the hardness values ​​of a plurality of the tensile test pieces in a first coordinate system; The hardness and tensile strength curve is fitted according to the plurality of the first coordinate points.

8. The welding zone strength detection method according to claim 1, characterized in that after the spectrum test piece is subjected to spectrum analysis to determine the content value of each element and combined with the tensile strength value, the method comprises: A tensile strength and element content curve is drawn by combining the element content value and the tensile strength value corresponding to each tensile test piece.

9. The welding zone strength detection method according to claim 8, wherein the step of drawing a tensile strength and element content curve by combining the element content value with the tensile strength value corresponding to each tensile test piece comprises: Marking a plurality of second coordinate points corresponding to the tensile strength values ​​and the element content values ​​of the tensile test pieces in a second coordinate system; The tensile strength and element content curve is fitted according to the plurality of the second coordinate points.

10. The welding zone strength detection method according to claim 1, wherein the hardness value and element content value at the target steel weld are determined, and the target tensile strength value at the target steel weld is deduced from the tensile strength, element content and hardness curve, including: Respectively measuring the hardness value and element content value at the weld of the target steel material; Determining the tensile strength, element content and hardness curve of the sample plate corresponding to the target steel weld; The tensile strength target value is determined according to the hardness value and element content value at the weld of the target steel material in the tensile strength, element content and hardness curve.

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