CN111948002A - Experimental method for weld characteristic region deformation damage evolution law - Google Patents
Experimental method for weld characteristic region deformation damage evolution law Download PDFInfo
- Publication number
- CN111948002A CN111948002A CN202010785545.3A CN202010785545A CN111948002A CN 111948002 A CN111948002 A CN 111948002A CN 202010785545 A CN202010785545 A CN 202010785545A CN 111948002 A CN111948002 A CN 111948002A
- Authority
- CN
- China
- Prior art keywords
- tensile
- weld joint
- sample
- deformation
- welding seam
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
Images
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N1/00—Sampling; Preparing specimens for investigation
- G01N1/28—Preparing specimens for investigation including physical details of (bio-)chemical methods covered elsewhere, e.g. G01N33/50, C12Q
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N1/00—Sampling; Preparing specimens for investigation
- G01N1/28—Preparing specimens for investigation including physical details of (bio-)chemical methods covered elsewhere, e.g. G01N33/50, C12Q
- G01N1/32—Polishing; Etching
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N3/00—Investigating strength properties of solid materials by application of mechanical stress
- G01N3/02—Details
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N3/00—Investigating strength properties of solid materials by application of mechanical stress
- G01N3/02—Details
- G01N3/04—Chucks
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N3/00—Investigating strength properties of solid materials by application of mechanical stress
- G01N3/02—Details
- G01N3/06—Special adaptations of indicating or recording means
- G01N3/068—Special adaptations of indicating or recording means with optical indicating or recording means
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N3/00—Investigating strength properties of solid materials by application of mechanical stress
- G01N3/08—Investigating strength properties of solid materials by application of mechanical stress by applying steady tensile or compressive forces
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E30/00—Energy generation of nuclear origin
- Y02E30/30—Nuclear fission reactors
Landscapes
- Physics & Mathematics (AREA)
- Health & Medical Sciences (AREA)
- Life Sciences & Earth Sciences (AREA)
- Chemical & Material Sciences (AREA)
- Analytical Chemistry (AREA)
- Biochemistry (AREA)
- General Health & Medical Sciences (AREA)
- General Physics & Mathematics (AREA)
- Immunology (AREA)
- Pathology (AREA)
- Investigating Strength Of Materials By Application Of Mechanical Stress (AREA)
Abstract
The invention discloses a method for testing the evolution law of deformation damage of a characteristic region of a welding seam, which comprises the steps of selecting a sample processing section, wherein the processing section comprises the whole welding seam and a first base metal and a second base metal which are connected with two sides of the welding seam, and the lengths of the first base metal and the second base metal are greater than that of a sample clamping section; designing a tensile sample structure containing the full wall thickness of a welding seam; cutting the tensile sample structure from the thickness direction along a plane perpendicular to the direction of the welding seam by slow wire cutting; polishing and corroding the welding seam of the tensile sample structure; carrying out tensile loading on a tensile sample structure, and carrying out deformation in-situ observation on the surface of the tensile sample structure in the experimental process; and respectively carrying out weld strength matching analysis, characteristic region strain evolution process analysis and weld damage generation and evolution process analysis to complete weld characteristic region deformation damage evolution rule experiments. The invention lays a foundation for the safety evaluation and the safety protection of the welding line.
Description
Technical Field
The invention belongs to the technical field of weld mechanical property distribution testing, and particularly relates to an experimental method for a weld characteristic region deformation damage evolution rule.
Background
The safety of the oil and gas pipeline, which is a main mode of energy supply in modern society, has a crucial influence on the transportation and storage of energy. The failure accident of the oil and gas pipeline often causes a great deal of problems such as serious economic loss, casualties, environmental pollution and the like, so the service safety of the oil and gas pipeline is more and more valued by operators. The welding line is used as a weak link of the oil and gas pipeline, and the mechanical property of the welding line has important influence on the safety service of the pipeline. With more and more safety accidents caused by welding seams, people can further and further study the mechanical behavior of the welding seams. From the perspective of safety evaluation and safety protection, it is of great significance to grasp the deformation and failure mechanism of the weld joint.
In the welding process of the welding seam, the mechanical properties of the finally formed welding seam in different areas show larger difference due to the influence of parameters such as welding rod materials, welding processes, welding current and the like of different welding layers. Because each area is small, the processing of the sample is difficult, so the characterization technology of the tensile mechanical property difference of the weld microcell also becomes a great problem in the actual engineering research. At present, the relevant standards are all that the welding seam is used as an integral structure to be researched, the macroscopic mechanical property of the welding seam is obtained, and the contribution of different characteristic areas of the welding seam to the deformation and the failure of the welding seam cannot be distinguished. When the failure mechanism of the welding seam is researched, most theories and finite element simulations are used for researching the macroscopic failure process of the welding seam by assuming the welding seam as a uniform material, and the method is inaccurate, because the mechanical property difference of different areas of the welding seam is large, the deformation of the welding seam and the great difference between the failure process and the uniform material are inevitably caused. Therefore, an experimental means is urgently needed to research the deformation difference and failure mechanism of different characteristic regions in the process of bearing the weld.
Disclosure of Invention
The invention aims to solve the technical problem of providing an experimental method for the evolution law of deformation damage of a characteristic region of a welding seam aiming at the defects in the prior art, and designs a full-wall-thickness sample shape and a cutting method by utilizing the transverse and longitudinal geometric shape characteristics of the welding seam. Meanwhile, by combining a metal corrosion visualization technology, a quasi-static stretching technology and a DIC technology, the deformation distribution and the failure process of a weld joint characteristic region under a tensile load are represented by a deformation in-situ observation technology, the position of a weld joint weak region and the dynamic process of deformation failure are integrally depicted, an experimental basis is provided for the failure mechanism research of the pipeline weld joint, and an experimental basis is provided for the safety evaluation and the safety protection of the weld joint.
The invention adopts the following technical scheme:
a method for testing a deformation damage evolution law of a weld joint characteristic region comprises the following steps:
s1, selecting a sample processing section, wherein the processing section comprises a whole welding seam and a first base material and a second base material which are connected with the two sides of the welding seam, and the lengths of the first base material and the second base material are larger than that of the sample clamping section;
s2, designing a tensile sample structure containing the full wall thickness of a welding seam;
s3, cutting the tensile sample structure from the thickness direction along a plane perpendicular to the direction of the welding seam by slow wire cutting;
s4, polishing and corroding the welding seam of the tensile sample structure;
s5, carrying out tensile loading on the tensile sample structure processed in the step S4, and carrying out deformation in-situ observation on the surface of the tensile sample structure in the experimental process;
and S6, respectively carrying out weld strength matching analysis, characteristic region strain evolution process analysis and weld damage generation and evolution process analysis to complete weld characteristic region deformation damage evolution rule experiments.
Specifically, in step S2, the weld specimen structure includes a weld region, the weld region is an inverted frustum-shaped structure and is disposed between the first base material and the second base material, a first heat affected zone is disposed between the weld region and the first base material, a second heat affected zone is disposed between the weld region and the second base material, and the weld region is sequentially a weld cap layer, a weld filling layer, and a root welding layer from top to bottom.
Furthermore, the welding seam sample structure comprises a transverse tensile sample, the transverse tensile sample is used for researching that the welding seam is subjected to tensile load perpendicular to the welding seam direction and is of a variable-thickness plate-shaped structure, the plane of the transverse tensile sample is perpendicular to the welding direction of the welding seam area, and the length direction of the transverse tensile sample spans the welding seam area and the first base material and the second base material on two sides.
Furthermore, the two ends of the transverse tensile sample are clamping sections, the middle of the transverse tensile sample is a testing section, the clamping sections are a first base material and a second base material, the thickness of the clamping sections is 1-2 times of that of the testing sections, for welding seams in butt joint with the same wall thickness, the width of the transverse tensile sample is the wall thickness of the first base material or the second base material, for welding seams in butt joint with different wall thicknesses, the width of the clamping sections is equal to the minimum value of the wall thickness of the base materials, the length direction of the testing sections comprises the whole welding seams and 2-3 mm of the first base material and the second base material respectively, and the clamping sections on the two sides are in.
Furthermore, the welding seam sample structure comprises a longitudinal tensile sample, the longitudinal tensile sample is used for researching that the welding seam is subjected to tensile load along the welding seam direction, the longitudinal tensile sample is of a variable-thickness plate-shaped structure, the plane of the longitudinal tensile sample is along the welding direction of the welding seam area and is perpendicular to the surface of the welding seam area, the processing position of the longitudinal tensile sample is the longitudinal middle plane of the welding seam area, and the length of the longitudinal tensile sample is distributed along the welding seam area.
Furthermore, the two ends of the longitudinal tensile sample are clamping sections, the middle of the longitudinal tensile sample is a testing section, and the thickness of each clamping section is 1-2 times that of the testing section; the length of the testing section is 1-2 times of the wall thickness of the base material, and the testing section is in transitional connection with the clamping sections on the two sides through arc surfaces.
Specifically, step S5 specifically includes:
s501, clamping the corroded tensile sample structure on a clamp, enabling the distance between the testing section of the tensile sample structure and the two clamps to be the same, enabling the length direction of the tensile sample structure to be perpendicular to the horizontal direction, and marking the clamping position of the clamp on the clamping section of the tensile sample structure
S502, recording a corroded surface of the tensile sample structure by using a high-speed camera, wherein a test section of the tensile sample structure is located at the midpoint of a picture of the high-speed camera, and shooting a picture of the tensile sample structure for comparison;
s503, taking down the tensile sample structure, and spraying uniformly distributed speckles on the surface of the corroded test section of the tensile sample structure;
s504, the tensile sample structure is installed at the same position again, quasi-static tensile is conducted on the tensile sample structure, meanwhile, a high-speed camera is used for shooting the deformation condition of the surface of the tensile sample structure in the experiment process until the test section of the sample is deformed greatly and damaged;
s505, processing the picture of the tensile sample structure deformation process to obtain the distribution change history of deformation of the characteristic region along with tensile time in the tensile load process of the welding line, and obtaining the initial position and the evolution process of the damage of the characteristic region of the welding line.
Specifically, in step S6, the weld strength and weakness matching analysis specifically includes:
analyzing DIC processing results obtained by a weld transverse tensile test, arranging surface strain distribution pictures of a test section of a sample in the obtained weld transverse tensile test process along with time, drawing tensile load-time data output by a quasi-static tensile testing machine into a curve by using data processing software, wherein the horizontal axis is time, and the vertical axis is tensile load;
observing the strain distribution conditions of the result pictures at different moments, searching for a picture of the damage on the surface of the sample and corresponding time, and if the damage occurs at the position of the welding seam, the welding seam is in weak matching;
if the damage occurs at the position of the base material, the welding seam is in strong matching; and meanwhile, the tensile load corresponding to the damage of the surface of the sample is obtained through a tensile load-time curve, and the tensile load is divided by the cross section area of the test section of the sample to obtain the tensile strength of the weak area of the welding seam.
Specifically, in step S6, the characteristic region strain evolution process specifically includes:
for a transverse tensile test, on a photo processed by DIC, taking a region from a weld joint cover surface layer, a filling layer, a welding heel, heat affected zones at two sides and a first base material region and a second base material region at two sides respectively, deriving a change curve of an average strain value in each region along with time, drawing each change curve in the same graph, observing the change trend of the strain of each region along with time, analyzing the difference between deformation speeds of different regions, and obtaining deformation leading regions and deformation capacity differences at different positions in the weld joint at different tensile deformation stages;
for a longitudinal tensile test, on a photo processed by DIC, taking a region on a weld joint cover layer, a filling layer and a weld heel respectively, deriving a change curve of an average strain value in each region along with time, drawing each change curve in the same graph, observing the change trend of the strain of each region along with time, analyzing the difference between deformation speeds of different regions, and obtaining deformation leading regions and deformation capacity differences of different positions in the weld joint at different tensile deformation stages.
Specifically, in step S6, the weld damage generation and evolution process specifically includes:
arranging the strain distribution map of the welding seam after DIC treatment along with time, observing the change of the strain concentration area of the welding seam along with the time, and simultaneously searching the initial position of the damage of the welding seam and the expansion path of the damage of the welding seam.
Compared with the prior art, the invention has at least the following beneficial effects:
according to the experimental method for the deformation damage evolution law of the characteristic region of the welding seam, different regions of the cross section of the welding seam are distinguished by using the corrosive liquid, and the sample is designed according to the size of each region of the welding seam, so that the size of the sample can be increased to the maximum extent, the processing difficulty of the sample can be reduced, and the tensile mechanical property test of different regions can be met; the test sample is processed by utilizing a linear cutting technology, so that the accurate processing of the test sample in the welding seam area is ensured, the tensile property and the distribution rule of different areas of the welding seam can be systematically mastered through a tensile test, experimental data are provided for the safety evaluation of the welding seam, and the precision of the safety evaluation of the welding seam can be improved.
Furthermore, the sample designed by the invention comprises the full wall thickness of the welding seam, and the deformation nonuniformity of the welding seam and the base material caused by the structural effect of the welding seam can be observed and researched through experiments.
Furthermore, the transverse tensile sample testing section comprises the whole cross section of the welding seam, and the deformation distribution conditions of the welding seam and the base material in the characteristic area of the welding seam can be researched through a tensile test when the welding seam and the base material are subjected to stress load perpendicular to the welding direction, so that the transverse deformation weak area of the welding seam comprising the structural effect can be mastered.
Furthermore, the thickness of the transverse tensile sample is reduced in the testing section, and the testing section and the clamping section are in smooth transition through the arc surface, so that the concentration of the main deformation area of the sample on the testing section is ensured, the stress concentration of the transition area is avoided, and the reliability of the test is improved.
Furthermore, the longitudinal tensile sample is completely processed from the welding seam material and is used for researching the deformation distribution condition of the welding seam on the cover surface layer, the filling layer and the welding root part of the welding seam when the welding seam is subjected to stress load along the welding direction, so that the longitudinal deformation weak area of the welding seam containing the structural effect is mastered.
Furthermore, the longitudinal tensile test sample contains the height of the whole welding line in the width direction, the thickness of the test section is reduced, and the test section and the clamping section are in smooth transition through the arc surface, so that the concentration of the main deformation area of the test sample on the test section is ensured, the stress concentration of the transition area is avoided, and the reliability of the test is improved.
Further, in the experimental process, speckles are sprayed on the corroded test section of the sample, and the distribution change of the speckles on the surface of the sample can be observed by combining a high-speed camera, so that the deformation condition of the test section of the sample is indirectly reflected.
Furthermore, in the field of safety evaluation, the performance of a welding seam is generally replaced by the performance of a base material for evaluation, and for a welding seam with weak matching, the evaluation method is too aggressive, so that the strong and weak matching properties of the welding seam must be mastered first, and the evaluation parameters can be reasonably selected. The method provides an analysis method for the strength and the weakness of the welding line, and can provide reference for the parameter value problem of the pipeline safety evaluation.
Furthermore, by extracting strain history curves in different characteristic regions of the sample, the deformation speed and the deformation amount of different characteristic regions of the welding seam can be intuitively reflected in a chart form, and a basis is provided for the strain capacity analysis of the welding seam.
Furthermore, the DIC analysis is used for researching the deformation distribution of the sample, so that the initial position of the sample damage can be found, and a basis is provided for the damage protection of the welding seam.
In conclusion, the sample design of the invention considers the transverse and longitudinal structural effects of the welding seam, and the experimental result is more in line with the actual engineering condition; deformation in-situ observation is carried out by the DIC technology, deformation capacity of different areas of the welding line can be analyzed, weak areas of the welding line can be mastered, and a foundation is laid for safety evaluation and safety protection of the welding line.
The technical solution of the present invention is further described in detail by the accompanying drawings and embodiments.
Drawings
FIG. 1 is a sample design and test flow for the tensile sample design and experiment method of the present invention;
FIG. 2 is a schematic view of weld micro-region structure distribution;
FIG. 3 is a cross-direction tensile specimen layout of a weld seam proposed by the present invention, wherein (a) is a schematic front view of the specimen and (b) is a schematic side view of the specimen;
FIG. 4 is a design drawing of a longitudinal tensile specimen of a weld seam proposed by the present invention, wherein (a) is a schematic front view of the specimen and (b) is a schematic side view of the specimen;
fig. 5 is a DIC software processing result picture of the characteristic region deformation distribution change and damage evolution process during the transverse stretching of the weld seam obtained in the embodiment.
Wherein: 1. a first base material; 2. a second base material; 3. a weld capping layer; 4. a weld filler layer; 5. root welding layer; 6. a first heat-affected zone; 7. a second heat-affected zone; 8. a weld region; 9. a testing section; 10. a clamping section.
Detailed Description
The invention provides a method for testing the evolution law of deformation damage of a weld joint characteristic region, which designs a full-wall thickness sample shape and a cutting method by utilizing the characteristics of transverse and longitudinal geometric shapes. Meanwhile, by combining a metal corrosion visualization technology, a quasi-static stretching technology and a DIC technology, the deformation distribution and the failure process of a weld joint characteristic region under a tensile load are represented by a deformation in-situ observation technology, the position of a weld joint weak region and the dynamic process of deformation failure are integrally depicted, an experimental basis is provided for the failure mechanism research of the pipeline weld joint, and an experimental basis is provided for the safety evaluation and the safety protection of the weld joint.
Referring to fig. 1, the method for testing the evolution law of deformation damage of the characteristic region of the weld joint of the present invention includes the following steps:
s1, selecting a sample processing section
Observing the welding seam material, and marking the parts containing geometrical defects such as misalignment, undercut, welding beading and the like; and carrying out nondestructive detection on the welding seam, and marking welding defect parts such as surface cracks, incomplete penetration, incomplete fusion and the like. And selecting a part which meets the research characteristics as a sample processing section, wherein the processing section comprises the whole welding line and a first parent metal 1 and a second parent metal 2 which are connected with the whole welding line, and the length of the first parent metal 1 and the second parent metal 2 is greater than that of a clamping section 10 of the sample.
S2 sample structure design
In order to represent the deformation distribution condition of a characteristic region in the whole deformation process of a welding seam and ensure that the deformation of a sample is intensively distributed in the welding seam region, the invention provides a tensile sample containing the full wall thickness of the welding seam. The structural design of the welding seam sample is divided into a transverse tensile sample and a longitudinal tensile sample.
The transverse tensile sample is designed for researching that a welding seam is subjected to tensile load in a direction perpendicular to the welding seam, the tensile sample is in a plate shape with variable thickness, the plane of the sample is perpendicular to the welding direction of the welding seam, and the length direction of the sample spans the welding seam and base materials on two sides. The two ends of the sample are clamping sections, the middle of the sample is a testing section, the clamping sections are base materials, the thickness of the clamping sections is 1-2 times thicker than that of the middle testing section, for welding seams butted with the same wall thickness, the width of the sample is the wall thickness of the base materials, and for welding seams butted with different wall thicknesses, the width of the clamping sections is equal to the minimum value of the wall thickness of the base materials, so that the influence of the structural effect on loading is eliminated. The length direction of the test section comprises the cross section of a welding seam and 2-3 mm of partial base materials on two sides, the thickness of the base materials is small, and the base materials are in transition connection with the clamping sections on two sides through arc surfaces.
The longitudinal tensile sample is designed for researching tensile load of a welding seam along the direction of the welding seam, the tensile sample is in a plate shape with variable thickness, the plane of the sample is along the welding direction of the welding seam and is vertical to the surface of the welding seam, the processing position of the sample is the longitudinal middle surface of the welding seam, and the length of the sample is along the distribution direction of the welding seam. The two ends of the sample are provided with clamping sections, the middle of the sample is provided with a testing section, and the thickness of each clamping section is 1-2 times thicker than that of the middle testing section. The test section is 1-2 times of the wall thickness of the base material, is thinner and is in transition connection with the clamping sections on the two sides through arc surfaces.
The thickness of the tensile sample test section is calculated by the method that the sigma multiplied by W multiplied by H is less than 80% of the measuring range of the test equipment, wherein the sigma is the yield strength of the welding seam material, the H is the thickness of the test sample, and the W is the width of the test section.
S3, cutting the sample
The test specimens were cut out in the thickness direction by slow wire cutting along a plane perpendicular to the direction of the weld. For butt welding seams with different wall thicknesses, the clamping section on the thick wall side of the sample is machined to be the same as the thin wall side through wire cutting, so that the bending component generated in the plane of the sample due to the fact that the clamping widths of the two ends are different in the stretching process is prevented.
S4, polishing and corroding weld joint
And (3) polishing the surface of the test section of the test sample by using fine sand paper until the surface is smooth and has no visible scratches, bulges, pits and the like, and corroding one surface of the test section by using a welding seam corrosive liquid to show a heat affected zone, a root welding layer, a filling layer and a cover surface layer of a welding seam.
S5 deformation in-situ observation experiment
The invention uses a quasi-static tensile testing machine to carry out tensile loading on the sample, and simultaneously uses a high-speed camera to carry out deformation in-situ observation on the surface of the sample in the experimental process. The method specifically comprises the following steps:
s501, designing and processing a tensile sample clamp according to the size of a weld tensile sample; clamping the corroded sample on a clamp of a tensile testing machine, adjusting the clamping position of the sample to ensure that the distance between a sample testing section and the two clamps is the same and the length direction of the sample is vertical to the horizontal direction, and marking the clamping position of the clamp on the sample clamping section by using a marking pen so as to be convenient for re-clamping the sample after subsequent speckles are sprayed;
s502, opening the high-speed camera, adjusting parameters such as an aperture, a focal length and resolution of the high-speed camera to enable a shot surface picture of the sample to be clear and the resolution to be proper, adjusting a lens of the high-speed camera to enable the lens to be opposite to the corroded surface of the sample, enabling a test section of the sample to be located in the middle of a picture, and shooting a picture of the sample for comparison;
s503, taking down the sample, spraying uniformly distributed speckles on the corroded surface of the test section of the sample, and preparing for tracking sample deformation by a high-speed camera;
s504, the sample is installed on the stretching experiment machine again at the same position as the first time, the quasi-static stretching experiment machine is used for quasi-static stretching of the sample, and meanwhile, a high-speed camera is used for shooting the deformation condition of the surface of the sample in the experiment process until the test section of the sample is deformed greatly and damaged;
s505, processing a picture of a sample deformation process shot by a high-speed camera by utilizing DIC (Digital Image Correlation, DIC for short) software to obtain the distribution change history of deformation of a characteristic region along with stretching time in the process of stretching load of a welding seam, observing the region with concentrated welding seam strain, so as to master the strain distribution condition of the characteristic region of the welding seam, provide reference for optimizing the structure of the welding seam, and simultaneously, obtaining the initial position and the evolution process of the damage of the characteristic region of the welding seam through DIC processing results, thereby laying a foundation for the research of the damage evolution mechanism of the welding seam.
S6 analysis of Damage mechanism
The method for analyzing the welding seam deformation damage mechanism provided by the invention comprises the following steps: the method comprises the steps of weld strength and weakness matching analysis, a characteristic region strain evolution process and a weld damage generation and evolution process. The specific process is as follows:
and (3) strong and weak matching analysis of welding seams: and analyzing DIC processing results obtained by the transverse weld joint tensile test, arranging surface strain distribution pictures of a test section of the sample in the transverse weld joint tensile test process obtained by DIC along with time, and drawing tensile load-time data output by the quasi-static tensile testing machine into a curve by using data processing software, wherein the horizontal axis is time, and the vertical axis is tensile load. Observing the strain distribution conditions of the DIC result pictures at different moments, searching the pictures with damage on the surface of the sample and the corresponding time, and if the damage occurs at the position of the welding seam, determining that the welding seam is in weak matching; if the damage occurs at the base material position, the weld is a strong match. And meanwhile, obtaining the corresponding tensile load when the surface of the sample is damaged through a tensile load-time curve, and dividing the tensile load by the cross section area of the test section of the sample to obtain the tensile strength of the weak area of the welding line.
And (3) a characteristic region strain evolution process: for a transverse tensile test, on a photo processed by DIC, a small area is respectively taken in a welding seam cover layer, a filling layer, a welding heel, heat affected zones at two sides and base metal areas at two sides, a change curve of an average value of strain in each area along with time is derived, each curve is drawn in the same graph, the change trend of the strain of each area along with time is observed, the difference between deformation speeds of different areas is analyzed, the deformation leading area inside the welding seam at different tensile deformation stages and the deformation capacity difference of different positions are obtained, and a basis is provided for a welding seam damage mechanism. For a longitudinal tensile test, on a photo processed by DIC, a small area is respectively taken on a welding seam cover layer, a filling layer and a welding heel, a change curve of an average strain value in each area along with time is derived, each curve is drawn in the same graph, the change trend of the strain of each area along with time is observed, the difference between deformation speeds of different areas is analyzed, the deformation leading area inside the welding seam at different tensile deformation stages and the deformation capacity difference of different positions are obtained, and a basis is provided for a welding seam damage mechanism.
The weld damage generation and evolution process: and arranging the welding line strain distribution graph after DIC treatment along with time, observing the change of a welding line strain concentration area along with the time, and simultaneously searching the initial position and the extended path of the welding line damage, thereby laying a foundation for researching the welding line damage evolution process.
In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, but not all, embodiments of the present invention. The components of the embodiments of the present invention generally described and illustrated in the figures herein may be arranged and designed in a wide variety of different configurations. Thus, the following detailed description of the embodiments of the present invention, presented in the figures, is not intended to limit the scope of the invention, as claimed, but is merely representative of selected embodiments of the invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
Examples
The embodiment is an experimental method for a transverse stretching deformation damage evolution rule of a full-automatic weld ring weld joint characteristic region. The circumferential weld is a butt circumferential weld of the same steel pipe, a first base material 1 of the butt steel pipe is X80 steel, a second base material 2 of the butt steel pipe is X80 steel, the outer diameter of the butt steel pipe is 1422mm, and the thickness of the butt steel pipe is 25.7 mm.
The invention provides an experimental method for a deformation damage evolution rule of a weld joint characteristic region, which comprises the following steps: the method comprises the following steps of sample processing section selection, sample structure design, sample cutting, welding line polishing and corrosion and deformation in-situ observation experiment.
Step 1: specimen processing segment selection
Observing the welding seam material, and marking the parts containing geometrical defects such as misalignment, undercut, welding beading and the like; and carrying out nondestructive detection on the welding seam, and marking welding defect parts such as surface cracks, incomplete penetration, incomplete fusion and the like. And selecting a part which accords with the research characteristics as a sample processing section, wherein the sample processing section has the length of 300mm along the circumferential direction of the circumferential weld joint, and the length of the vertical weld joint is 120 mm.
Step 2: design of sample structure
The tensile sample is in a plate shape with variable thickness, the width direction of the sample is perpendicular to the welding direction of the welding seam, and the length direction of the sample spans the welding seam and the parent metal at two sides. The width of the test sample is 20mm, the length of the test section is 9 mm, the thickness of the test section is 2mm, and the test section comprises the whole welding line in the middle and the base metal at two sides, each of which is 2mm long. The length of the clamping section 10 on both sides is 30mm, the thickness is 4mm, and the wall thickness changing positions of the clamping section 10 and the testing section 9 are in smooth transition through an arc with the radius of 2 mm.
And step 3: cutting of test specimens
The test specimens were cut out in the thickness direction by slow wire cutting along a plane perpendicular to the direction of the weld.
And 4, step 4: weld polishing and corrosion
Referring to fig. 2, the weld micro-area structure is an inverted frustum structure and is disposed between the first base material 1 and the second base material 2, a first heat affected zone 6 is disposed between the weld micro-area structure and the first base material 1, a second heat affected zone 7 is disposed between the weld micro-area structure and the second base material 2, and the weld capping layer 3, the weld filling layer 4 and the root welding layer 5 are sequentially disposed from top to bottom.
Referring to fig. 3 and 4, the weld zone 8 is disposed between the clamping segments 10, the surface of the test segment 9 of the test specimen is polished with fine sand paper until the surface is smooth without visible scratches, protrusions, pits, etc., and one surface of one test segment 9 is corroded with a weld corrosion solution to reveal the heat affected zone 6, the root weld 5, the filler layer 4, and the cover layer 3 of the weld.
And 5: deformation in situ observation experiment
In the embodiment, a domestic electronic universal tester is used for stretching and loading the sample, and meanwhile, the picture is taken by using an Aramis picture taking device of a GOM company, wherein the picture taking frame rate is 0.5 HZ. The method specifically comprises the following steps:
firstly, designing and processing a tensile sample clamp according to the size of a welding seam tensile sample.
And secondly, clamping the corroded sample on a clamp of a tensile testing machine, adjusting the clamping position of the sample to ensure that the distance between the test section 9 of the sample and the two clamps is the same and the length direction of the sample is vertical to the horizontal direction, and marking the clamping position of the clamp on the clamping section 10 of the sample by using a marking pen so as to be convenient for re-clamping the sample after subsequent spot spraying.
And thirdly, opening the high-speed camera, adjusting parameters such as an aperture, a focal length and resolution of the high-speed camera to enable the shot surface picture of the sample to be clear and the resolution to be proper, adjusting a lens of the high-speed camera to enable the lens to be opposite to the corroded surface of the sample, enabling the sample testing section 9 to be located at the center of the picture, and shooting a sample picture for comparison.
And fourthly, taking down the sample, and spraying uniformly distributed speckles on the surface of the corroded test section 9 of the sample to prepare for the high-speed camera to track the deformation of the sample.
And fifthly, re-installing the sample on the same position on the tensile testing machine as the first time, performing quasi-static tensile on the sample by using the quasi-static tensile testing machine, and shooting the deformation condition of the surface of the sample in the testing process by using the high-speed camera until the loading force reaches a required value or the test section of the sample is damaged.
And sixthly, processing a picture of the sample deformation process shot by the high-speed camera by utilizing DIC software to obtain the distribution change condition of deformation of the characteristic region along with the tensile time in the tensile load process of the welding seam, and observing the region with concentrated welding seam strain, thereby mastering the strain distribution condition of the characteristic region of the welding seam and providing reference for the optimization of the welding seam structure. Meanwhile, the initial position and the evolution process of the damage of the characteristic region of the welding seam are obtained through DIC processing results, and a foundation is laid for the research of the damage evolution mechanism of the welding seam.
Referring to fig. 5, the deformation distribution of the sample during the stretching process is arranged, from the initial non-deformation to the final local failure, it can be clearly and intuitively seen that due to the joint effect of the weld structure and the nonuniformity of the weld material, the deformation distribution of different characteristic regions of the weld is very nonuniform, the largest deformation region is concentrated in two heat affected zones, and as the deformation is further increased, the root portion starts to fail and starts to expand along the heat affected zone on one side of the low-grade base material. Therefore, the DIC processing result obtained by the method can intuitively and clearly analyze the weak area in the welding seam deformation process, can grasp the deformation difference of the characteristic area of the welding seam, and provides a basis for safety evaluation and protection of the welding seam.
Step 6: analysis of Damage mechanisms
The transverse tensile deformation and damage mechanism of the circumferential weld in the embodiment can be obtained from the deformation in-situ observation experiment result, and the whole test piece starts to generate strain concentration on the weld filling layer 4 after being uniformly deformed by the elastic section. This is because the material strength of the weld filler layer is smaller than that of the first base material 1 and the second base material 2. As the tensile test progresses, the strain of the weld filler layer 4 starts to be transferred and concentrated on the first heat-affected zone 6 and the second heat-affected zone 7 on both sides and forms a V shape, and then the test piece starts to form an initial crack from the root weld layer 5, and the test piece is torn along the heat-affected zones in turn.
In conclusion, according to the experimental method for the evolution law of deformation damage of the characteristic region of the weld joint, the transverse and longitudinal tensile test samples of the full wall thickness of the weld joint are designed, and the structural effect of the weld joint is introduced into the whole section of the test sample containing the weld joint, so that the experimental result is closer to the actual engineering condition. In the process of stretching a sample, a speckle jet technology and a high-speed camera are combined to observe the deformation condition of the surface of the sample, DIC software is used for carrying out strain treatment on a test section of the sample after an experiment, the deformation distribution conditions of different characteristic regions of a welding seam are visually reflected in the form of a curve and a picture, the deformation capacity and the damage evolution rule of the different characteristic regions of the welding seam are mastered, the strength matching relation between the welding seam and a parent metal is obtained, and a foundation is laid for safety evaluation and safety protection of the welding seam.
The above-mentioned contents are only for illustrating the technical idea of the present invention, and the protection scope of the present invention is not limited thereby, and any modification made on the basis of the technical idea of the present invention falls within the protection scope of the claims of the present invention.
Claims (10)
1. A method for testing the evolution law of deformation damage of a weld joint characteristic region is characterized by comprising the following steps:
s1, selecting a sample processing section, wherein the processing section comprises a whole welding seam and a first base material and a second base material which are connected with the two sides of the welding seam, and the lengths of the first base material and the second base material are larger than that of the sample clamping section;
s2, designing a tensile sample structure containing the full wall thickness of a welding seam;
s3, cutting the tensile sample structure from the thickness direction along a plane perpendicular to the direction of the welding seam by slow wire cutting;
s4, polishing and corroding the welding seam of the tensile sample structure;
s5, carrying out tensile loading on the tensile sample structure processed in the step S4, and carrying out deformation in-situ observation on the surface of the tensile sample structure in the experimental process;
and S6, respectively carrying out weld strength matching analysis, characteristic region strain evolution process analysis and weld damage generation and evolution process analysis to complete weld characteristic region deformation damage evolution rule experiments.
2. The experimental method for the evolution law of weld joint characteristic region deformation damage according to claim 1, wherein in step S2, the weld joint sample structure comprises a weld joint region (8), the weld joint region (8) is an inverted frustum-shaped structure and is disposed between the first parent metal (1) and the second parent metal (2), a first heat affected zone (6) is disposed between the weld joint region (8) and the first parent metal (1), a second heat affected zone (7) is disposed between the weld joint region (8) and the second parent metal (2), and the weld joint region (8) is sequentially a weld joint cover layer (3), a weld joint filling layer (4) and a root welding layer (5) from top to bottom.
3. The experimental method for the evolution law of weld joint characteristic region deformation damage according to claim 2, characterized in that the weld joint sample structure comprises a transverse tensile sample, the transverse tensile sample is used for researching that the weld joint is subjected to tensile load perpendicular to the direction of the weld joint and is a variable-thickness plate-shaped structure, the plane of the transverse tensile sample is perpendicular to the welding direction of the weld joint region (8), and the length direction spans the weld joint region (8) and the first parent metal (1) and the second parent metal (2) on two sides.
4. The experimental method for the evolution law of the deformation damage of the characteristic region of the weld joint according to claim 3, characterized in that the two ends of the transverse tensile sample are clamping sections (10), the middle is a testing section (9), the clamping sections (10) are a first parent material (1) and a second parent material (2), the thickness of the clamping sections is 1-2 times of the thickness of the testing section (9), for the butt-jointed weld joint with the same wall thickness, the width of the transverse tensile sample is the wall thickness of the first parent material (1) or the second parent material (2), for the butt-jointed weld joint with different wall thicknesses, the width of the clamping sections (10) is equal to the minimum value of the wall thickness of the parent materials, the length direction of the testing section (9) comprises the whole weld joint and 2-3 mm of each of the first parent material and the second parent material, and the clamping sections (10) on the.
5. The experimental method for the evolution law of weld joint characteristic region deformation damage according to claim 2, characterized in that the weld joint sample structure comprises a longitudinal tensile sample, the longitudinal tensile sample is used for researching tensile load of the weld joint along the weld joint direction, the longitudinal tensile sample is a variable-thickness plate-shaped structure, the plane of the longitudinal tensile sample is along the weld joint direction of the weld joint region (8) and perpendicular to the surface of the weld joint region (8), the processing position of the longitudinal tensile sample is the longitudinal middle plane of the weld joint region (8), and the length is along the distribution direction of the weld joint region (8).
6. The experimental method for the evolution law of the deformation damage of the characteristic region of the weld joint as claimed in claim 5, wherein the two ends of the longitudinal tensile test sample are clamping sections (10), the middle part of the longitudinal tensile test sample is a testing section (9), and the thickness of each clamping section (10) is 1-2 times that of each testing section (9); the length of the test section (9) is 1-2 times of the wall thickness of the base material, and the test section (9) is in transition connection with the clamping sections (10) on the two sides through arc surfaces.
7. The weld joint characteristic region deformation damage evolution law experimental method according to claim 1, wherein the step S5 specifically comprises:
s501, clamping the corroded tensile sample structure on a clamp, enabling the distance between the testing section of the tensile sample structure and the two clamps to be the same, enabling the length direction of the tensile sample structure to be perpendicular to the horizontal direction, and marking the clamping position of the clamp on the clamping section of the tensile sample structure
S502, recording a corroded surface of the tensile sample structure by using a high-speed camera, wherein a test section of the tensile sample structure is located at the midpoint of a picture of the high-speed camera, and shooting a picture of the tensile sample structure for comparison;
s503, taking down the tensile sample structure, and spraying uniformly distributed speckles on the surface of the corroded test section of the tensile sample structure;
s504, the tensile sample structure is installed at the same position again, quasi-static tensile is conducted on the tensile sample structure, meanwhile, a high-speed camera is used for shooting the deformation condition of the surface of the tensile sample structure in the experiment process until the test section of the sample is deformed greatly and damaged;
s505, processing the picture of the tensile sample structure deformation process to obtain the distribution change history of deformation of the characteristic region along with tensile time in the tensile load process of the welding line, and obtaining the initial position and the evolution process of the damage of the characteristic region of the welding line.
8. The weld joint characteristic region deformation damage evolution law experimental method as claimed in claim 1, wherein in step S6, the weld joint strength matching analysis specifically comprises:
analyzing DIC processing results obtained by a weld transverse tensile test, arranging surface strain distribution pictures of a test section of a sample in the obtained weld transverse tensile test process along with time, drawing tensile load-time data output by a quasi-static tensile testing machine into a curve by using data processing software, wherein the horizontal axis is time, and the vertical axis is tensile load;
observing the strain distribution conditions of the result pictures at different moments, searching for a picture of the damage on the surface of the sample and corresponding time, and if the damage occurs at the position of the welding seam, the welding seam is in weak matching;
if the damage occurs at the position of the base material, the welding seam is in strong matching; and meanwhile, the tensile load corresponding to the damage of the surface of the sample is obtained through a tensile load-time curve, and the tensile load is divided by the cross section area of the test section of the sample to obtain the tensile strength of the weak area of the welding seam.
9. The weld joint characteristic region deformation damage evolution law experimental method as claimed in claim 1, wherein in step S6, the characteristic region strain evolution process specifically comprises:
for a transverse tensile test, on a photo processed by DIC, taking a region from a weld joint cover surface layer, a filling layer, a welding heel, heat affected zones at two sides and a first base material region and a second base material region at two sides respectively, deriving a change curve of an average strain value in each region along with time, drawing each change curve in the same graph, observing the change trend of the strain of each region along with time, analyzing the difference between deformation speeds of different regions, and obtaining deformation leading regions and deformation capacity differences at different positions in the weld joint at different tensile deformation stages;
for a longitudinal tensile test, on a photo processed by DIC, taking a region on a weld joint cover layer, a filling layer and a weld heel respectively, deriving a change curve of an average strain value in each region along with time, drawing each change curve in the same graph, observing the change trend of the strain of each region along with time, analyzing the difference between deformation speeds of different regions, and obtaining deformation leading regions and deformation capacity differences of different positions in the weld joint at different tensile deformation stages.
10. The weld joint characteristic region deformation damage evolution law experimental method as claimed in claim 1, wherein in step S6, the weld joint damage generation and evolution process specifically comprises:
arranging the strain distribution map of the welding seam after DIC treatment along with time, observing the change of the strain concentration area of the welding seam along with the time, and simultaneously searching the initial position of the damage of the welding seam and the expansion path of the damage of the welding seam.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202010785545.3A CN111948002B (en) | 2020-08-06 | 2020-08-06 | Weld joint characteristic region deformation damage evolution rule experimental method |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202010785545.3A CN111948002B (en) | 2020-08-06 | 2020-08-06 | Weld joint characteristic region deformation damage evolution rule experimental method |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN111948002A true CN111948002A (en) | 2020-11-17 |
| CN111948002B CN111948002B (en) | 2023-04-25 |
Family
ID=73331792
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202010785545.3A Active CN111948002B (en) | 2020-08-06 | 2020-08-06 | Weld joint characteristic region deformation damage evolution rule experimental method |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN111948002B (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112801944A (en) * | 2020-12-31 | 2021-05-14 | 东莞材料基因高等理工研究院 | Method and device for improving surface line marks of slow-speed wire cutting machine and cutting machine |
| CN113624671A (en) * | 2021-07-30 | 2021-11-09 | 中车工业研究院有限公司 | Welding joint corrosion tensile test method and test device |
| CN114383942A (en) * | 2022-01-12 | 2022-04-22 | 华东理工大学 | In-situ test method for stripping performance of brazed joint and in-situ test sample |
Citations (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| RU2007146319A (en) * | 2007-12-13 | 2009-06-20 | Открытое Акционерное общество "АВТОВАЗ" (RU) | WELDING TEST METHOD (OPTIONS) |
| CN102778403A (en) * | 2012-04-25 | 2012-11-14 | 湖南大学 | Welding seam material parameter identification method |
| JP2014102131A (en) * | 2012-11-19 | 2014-06-05 | Institute Of Nuclear Safety System Inc | Fracture strength evaluation method |
| CN104964886A (en) * | 2015-05-27 | 2015-10-07 | 东南大学 | Welded member fatigue stress and strain real-time non-contact type monitoring method |
| CN108362561A (en) * | 2018-02-02 | 2018-08-03 | 上海理工大学 | A kind of weld seam and the material mechanical performance of welding heat affected zone determine method |
| CN111044351A (en) * | 2019-12-16 | 2020-04-21 | 合肥通用机械研究院有限公司 | DIC technology-based weld joint creep deformation prediction method |
| CN111289395A (en) * | 2020-02-24 | 2020-06-16 | 天津商业大学 | Metal stress corrosion image testing method |
-
2020
- 2020-08-06 CN CN202010785545.3A patent/CN111948002B/en active Active
Patent Citations (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| RU2007146319A (en) * | 2007-12-13 | 2009-06-20 | Открытое Акционерное общество "АВТОВАЗ" (RU) | WELDING TEST METHOD (OPTIONS) |
| CN102778403A (en) * | 2012-04-25 | 2012-11-14 | 湖南大学 | Welding seam material parameter identification method |
| JP2014102131A (en) * | 2012-11-19 | 2014-06-05 | Institute Of Nuclear Safety System Inc | Fracture strength evaluation method |
| CN104964886A (en) * | 2015-05-27 | 2015-10-07 | 东南大学 | Welded member fatigue stress and strain real-time non-contact type monitoring method |
| CN108362561A (en) * | 2018-02-02 | 2018-08-03 | 上海理工大学 | A kind of weld seam and the material mechanical performance of welding heat affected zone determine method |
| CN111044351A (en) * | 2019-12-16 | 2020-04-21 | 合肥通用机械研究院有限公司 | DIC technology-based weld joint creep deformation prediction method |
| CN111289395A (en) * | 2020-02-24 | 2020-06-16 | 天津商业大学 | Metal stress corrosion image testing method |
Non-Patent Citations (2)
| Title |
|---|
| 汤忠斌 等: "焊缝结构微区材料力学性能研究", 《机械强度》 * |
| 魏亮鱼 等: "基于DIC方法的不同退火温度下Cu-Ni19合金损伤演变研究", 《工程力学》 * |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112801944A (en) * | 2020-12-31 | 2021-05-14 | 东莞材料基因高等理工研究院 | Method and device for improving surface line marks of slow-speed wire cutting machine and cutting machine |
| CN113624671A (en) * | 2021-07-30 | 2021-11-09 | 中车工业研究院有限公司 | Welding joint corrosion tensile test method and test device |
| CN114383942A (en) * | 2022-01-12 | 2022-04-22 | 华东理工大学 | In-situ test method for stripping performance of brazed joint and in-situ test sample |
Also Published As
| Publication number | Publication date |
|---|---|
| CN111948002B (en) | 2023-04-25 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN111948002A (en) | Experimental method for weld characteristic region deformation damage evolution law | |
| Siefert et al. | Evaluation of the creep cavitation behavior in Grade 91 steels | |
| Shojai et al. | Influence of pitting corrosion on the fatigue strength of offshore steel structures based on 3D surface scans | |
| Thomas | Analyzing the failure of welded steel components in construction systems | |
| CN111965030A (en) | Method for predicting tensile strength and yield strength of base metal and welding line of metal material | |
| Kozak et al. | Problems of determination of welding angular distortions of T-fillet joints in ship hull structures | |
| Abdulhameed et al. | The effect of internal pressure on the tensile strain capacity of X52 pipelines with circumferential flaws | |
| CN112393969A (en) | Axial surface type crack steel pipe explosion test device and fracture resistance evaluation method thereof | |
| Eshtayeh et al. | Nondestructive evaluation of welded joints using digital image correlation | |
| Fleury et al. | Fatigue performance of thick 6061-T6 aluminum friction stir welded joints with misalignment or channel defects | |
| Kalyanam et al. | Why conduct SEN (T) tests and considerations in conducting/analyzing SEN (T) testing | |
| Gueugnaut et al. | Ultrasonic phased array inspection of electrofused joints implemented in polyethylene gas piping systems | |
| Sorgente et al. | Evaluation of the strain behaviour of butt joints on AZ31 magnesium alloy thin sheets welded by Nd: YAG laser | |
| Kalyanam et al. | Mode mixity in the fracture toughness characterization of HAZ material using SEN (T) testing | |
| Hesse et al. | On the effect of weld defects on the fatigue strength of beam welded butt joints | |
| Sabry et al. | Experimental investigation on joining process of (plate to pipe) aluminum alloy 6082-T6 using friction stir welding | |
| Fuštar et al. | Fatigue tests of as-welded and HFMI treated S355 details with longitudinal and transverse attachments | |
| Ironside et al. | Pipeline dent management program | |
| Sekyi-Ansah et al. | Experimental studies on tee weldment joints (non-destructive testing) | |
| Vieltorf et al. | Online Detection of Part Fit-Up and Mating Variations in Friction Stir Welding | |
| Kah et al. | Methods of evaluating weld quality in modern production (Part 1) | |
| US3526948A (en) | Circular fillet weldability test | |
| KR102666005B1 (en) | Quality prediction method and system based on welding surface shape of resistance spot welding | |
| Pool | Effect of galvanization on the fatigue strength of high mast illumination poles | |
| Lu et al. | Integration of Welding, NDT, Mechanical Testing and Field Control When Using an ECA Flaw Acceptance Criteria in Pipeline Construction |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| GR01 | Patent grant | ||
| GR01 | Patent grant |