最新刊期
期 5 ， 2023
- 摘要：There are a lot of dissimilar material joints in the process of automobile lightweight application. This paper mainly reviews and prospects the research on the microstructure, properties, and prediction models of dissimilar aluminum alloy TIG, MIG, laser welding, friction stir welding joints under different prefabrication processes and welding conditions at home and abroad. Laser wire filling welding, laser-CMT hybrid welding, and riveting and gluing of dissimilar aluminum alloys have broad prospects in the field of sheet welding, and the effective method to improve the strength of high-strength aluminum alloy fusion welded joints is to regulate the composition of welding wires through microalloying and nanoparticle processing. Friction stir welding is the main method for high-quality connection of 2X/7X aluminum alloys, and new processes such as friction stir spot welding, prefabrication of dovetail grooves, the addition of nanoparticles in prefabricated holes, tool offset, etc. can effectively promote the high-strength connection of local aluminum/steel, aluminum/copper, aluminum/carbon fiber and other materials.关键词：dissimilar aluminum alloy;TIG welding;MIG welding;laser welding;friction stir welding
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发布时间：2023-06-12 - 摘要：For the welded reactor steam generator, on the one hand, the residual stress of the welded joint provides conditions for stress corrosion; on the other hand, the increase of service temperature in the advanced reactors will cause more obvious creep phenomenon. Based on the data provided in the Nims database and ASME standards, for two different welding structures, this paper calculates the residual stress of heat transfer tube plug circumferential welding at the high temperature end of Incoloy 800H material and the low temperature end of T22 material, and predicts the life of welded pipe plug under the creep fatigue interaction based on the linear damage accumulation criterion. The results show that the point of maximum residual tensile stress occurs at the root of the weld, and the residual stress of the grooved structure is higher than that of the non-grooved structure. Compared with the data provided by the Nims database, the life calculated by the ASME standard is more conservative. The life of the grooved structure is lower than that of the non-grooved structure.关键词：steam generator;residual stress;creep-fatigue;life expectancy
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发布时间：2023-06-12 - 摘要：New energy vehicles, aerospace and other vehicles with thin structure have greatly promoted the development and application of modern industrial lightweight. Laser welding is widely used in the sheet structure interconnection process as a key technology in the advanced manufacturing field. However, the welding deformation and prediction of sheet structure are still the core problems in this research field. Therefore, according to the research progress in the field of laser welding of stainless sheet plate steel, this paper comprehensively evaluates the research status in this field, systematically expounds the influence of the laser welding process of weld geometry on deformation, and generally analyzes the heat source model error, key technologies and innovative methods of welding deformation prediction. The aim is to clarify the process characteristics, influence mechanism and development trend of stainless-steel laser welding deformation, provide favorable reference for the field of sheet laser welding, and promote the wide application of new sheet lightweight structure in various manufacturing industries.关键词：stainless sheet plate steel;deformation prediction;laser beam welding;numerical simulation
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发布时间：2023-06-12 - 摘要：Girth weld is the weak point of long distance oil and gas pipeline, and its failure is generally induced by the co-effect of flaws within the girth weld and the sustained load. Using the Engineering Critical Assessment (ECA) technique based on applicable principles to assess flaws in welds can reduce repair rates and costs while ensuring safe pipeline operation. The Failure Assessment Diagram (FAD), which is based on the double criteria of plastic failure and fracture, is the most widely used method in ECA. This paper takes BS: 7910 as an example to analyze ECA technology based on the fracture behavior of girth welds, and discusses the possible problems of ECA technology during the evaluation of girth welds in oil and gas pipelines, including the determination of load stress parameters, the accurate identification of defects and the characterization of girth welds performance indicators. Under the background of rapid construction of oil and gas pipeline, further development of ECA technology is of significant for the safe operation of pipelines.关键词：oil and gas pipeline;girth weld;welding defects;engineering critical assessment (ECA)
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发布时间：2023-06-12 - 摘要：The high-quality connection between carbon fiber reinforced thermoplastic composites (CFRTP) and titanium alloy composite structure is the key to realize aircraft lightweight and high-strength manufacturing. In this paper, the laser high-speed rotary welding technology is used to connect the composite structure of CFRTP titanium alloy. By preparing grid micro textures with different sizes on the surface of titanium alloy, the effect of interface state on the strength of CFRTP titanium alloy joint is studied. The results show that the preparation of micro texture on the surface of titanium alloy can significantly improve the strength of the joint, and the micro texture under different wire spacing has a direct impact on the strength of the joint. The smaller the wire spacing, the higher the strength of the joint; Adding PA resin layer between the micro texture of CFRTP and titanium alloy is conducive to the production of high-strength joints.关键词：CFRTP;titanium alloy;laser welding;surface treatment;interface micro-textures
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发布时间：2023-06-12 -
Research Status of Influencing Factors and Evaluation Methods for Toughness of Pipeline Steel Joints
摘要：Partial failure of girth welds in long-distance pipelines is due to fracture due to insufficient weld toughness, which puts forward higher requirements for the toughness of long-distance pipelines. Firstly, the application and advantages and disadvantages of electrode arc welding, semi-automatic welding and fully automatic welding in pipeline steel welding are analyzed in detail. Secondly, the main factors affecting the toughness of welded joints are summarized: pipeline steel alloy composition, trace elements, microstructure of welded joints, residual stress, crystallographic characteristics and strength matching. Finally, the main evaluation methods for the toughness of welded joints: Charpy impact test, drop weight tear test (DWTT) and crack tip opening displacement (CTOD) test. It is also pointed out that the concept of strength matching needs to be further clarified, and the ductile fracture mechanism of joints with different strength matching needs to be further explored. Due to the influence of the slope, the heat-affected zones on both sides of the weld are asymmetrical. It is suggested that the impact, drop weight tear and CTOD experiments of the heat-affected zone in the welding process evaluation under mountainous conditions should be distinguished from the upper and lower grooves.关键词：pipeline steel;welding method;toughness;influencing factor;evaluation method- 27
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发布时间：2023-06-12
Important Issuse
- 摘要：TC4 is a typical α+β dual phase titanium alloy with good formability, weldability, and comprehensive properties that is widely used in aerospace field. In this paper, the microstructure, hardness, and phase composition of TC4 titanium alloy heat dissipation structural parts prepared by laser alloying (SLM) before and after heat treatment were tested and analyzed by using a metallographic microscope, a Vickers hardness tester, an X-ray diffractometer, and other equipment. The results show that with the increase in annealing temperature, the internal structure of the structural parts undergoes significant coarsening the α' Phase transition to the α+β Phase. When the annealing temperature is 1050 ℃, the hardness of the structure near the inner hole and far from the inner hole is 667 HV and 690 HV, respectively. The structural alloy is primarily composed of α'+β phase after 920 ℃ solution treatment. The hardness of the structure near the inner hole and far from the inner hole is 424.8 HV and 469.62 HV, respectively. After solution+aging heat treatment, the metastable structure of the structural member alloy will be decomposed to form dispersed α+β phase. At this time, the hardness of the structure near the inner hole and far from the inner hole decreased significantly, to 371.27 HV and 382.64 HV, respectively.关键词：TC4 titanium alloy;SLM;heat treatment;microstructure;hardness
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发布时间：2023-06-12 - 摘要：Laser heat treatment (LHT) can improve the surface wear resistance of high-strength pipeline steel to avoid defects such as pipe wall thinning and surface pits. Laser heat treatment (LHT) tests were carried out with different laser power on X100 pipeline steel plates. Dry sliding friction wear tests were conducted on the LHT samples. The microstructures of LHT plates were analyzed. The effect of laser heat treatment on the friction and wear properties of X100 pipeline steel was studied as well. The results show that laser heat treatment can induce extremely fine martensite on the surface of X100 pipeline steel with laser power in the range of 1 000~1 400 W, and the hardness of hardened zone increases considerably compared with that of base metal. The dry sliding friction coefficients of LHT samples are smaller than that of base metal without LHT. The depth and average hardness of hardened zone gradually increases with rising laser power level. With increasing laser power, the weight loss rate declines and the friction and wear resistance improves.关键词：laser heat treatment;X100 pipeline steel;friction and wear properties;martensite
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发布时间：2023-06-12 - 摘要：The thickness of galvanized steel sheet for car body is relatively thin, and it is easy to produce large deformation when welding and manufacturing by other methods. Therefore, it is of great theoretical and practical significance to develop the laser filler wire welding process for thinner galvanized steel sheet. In this paper, the experimental research on laser wire filling welding process is carried out for different kinds of galvanized steel sheets used for car bodies. The influence of key process parameters (laser power, welding speed, defocusing amount and wire feeding speed) on the weld surface and cross section was systematically studied. The microstructure characteristics and mechanical properties of welded joints were analyzed. The results show that when the laser power, welding speed, defocusing distance and wire feeding speed are well matched, the weld with less spatter and smooth surface can be obtained. The tensile specimen of welded joint broke in the base metal with weak strength. This study will provide a theoretical basis and technical support for high-quality welding and manufacturing of galvanized steel sheets.关键词：galvanized sheet;laser filler wire welding;process characteristics;microstructure;mechanical property
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发布时间：2023-06-12 - 摘要：The w(Ni) =60 nickel-base type (Ni-Cr-Mo) series alloy is widely used for LNG (liquefied natural gas) Marine vessels 9%Ni steel welding. For thin plate (thickness less than 5 mm) welding, the transverse bending test is easy to produce cracks. The research on this problem is lacking. In this paper, this study would investigate the reasons for the easy occurrence of unqualified cracking (bend surface crack length more than 3 mm)，through the combination of finite element analysis and process test the X7Ni9 steel sheet welded by manual (ENiCrMo-6) arc welding process. The results show that the main reason of bending cracking is that the base material and welding material are heterogeneous materials. The yield strength varies greatly. When the test plate thickness is too thin, the weld metal is overstretched and forced cracking beyond 4t requirement of the standard during the lateral bending test, which distorts the test results. The weld orifice defect are easy to occur on root weld by manual (ENiCrMo-6) arc welding process with poor weld formation under combined action of.which and crack lead to the sample fracture. The process improvement measures: increase the weld width to ensure sufficient plastic reserve when stretching, control the weld duct molding to improve the weld orifice defects; adopt longitudinal bending instead of transverse bending test. The process improvement measures are: increase the weld width to ensure sufficient plastic reserve when stretching; control the weld duct forming to improve the weld orifice defect.关键词：9%Ni steel;ENiCrMo-6;thin plate;transverse bending;crack
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发布时间：2023-06-12 - 摘要：2219 aluminum alloy has been widely used in the manufacture of rocket fuel tanks due to its excellent mechanical properties. FSW is one of the main welding processes of 2219 aluminum alloy. The microstructure and mechanical properties of the joint are directly affected by the morphology of the pin. In order to reveal the effect of the morphology of the pin on the joint performance, the welding numerical analysis was carried out by using semi-helical tri-arcs and full-helical tri-planes geometric structures, moreover, the mechanical properties of the joint under the welding of full-helical tri-planes pin with different thread characteristics were analyzed. The results showed that the effect of the pin geometry on the welding temperature field was slight, however, the flow field and strain rate were strong. Moreover, the connection between the semi-helical tri-arcs and the tunnel hole defect was closer. The experimental results showed that the influence of the characteristics of full-helical tri-planes pin on the microstructure and properties of 13 mm FSW joint were mainly caused by the difference of heat input and temperature distribution.关键词：2219 aluminum alloy;friction stir welding(FSW);pin;numerical analysis;welding defects
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发布时间：2023-06-12 - 摘要：Our Company has accepted a manufacturing project to weld some low carbon-stainless steel combined tubes with small diameter. Too small as tubes were, we couldn’t make them with regular welding procedure of “base layer -transition layer -coating layer” just like common combined plates, instead, we can only weld in this order “coating layer -transition layer -base layer” to get a joint only welding from one-side. The text researched deeply the theory of welding low carbon-stainless steel combined plates, analyzed the reason why it is impossible that overlying carbon steel onto the surface of stainless steel directly, and proposed creatively industrial pure iron as a new type of transition filler metal. We made use of the character of low carbon content in pure iron to avoid the problem of intergranular corrosion, in addition, the good plastic and toughness of pure iron overcame the crack problem occurred after overlying welding carbon steel material onto stainless steel surface. We have proved the reasonability of this method by conducting a series of experiments, and gotten a new procedure to weld low carbon-stainless steel combined tubes with small diameter eventually.关键词：combined tubes with small diameter;single side welding double side forming;industrial pure iron;overlying welding carbon steel
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发布时间：2023-06-12 - 摘要：In the practice of regular inspection of pressure pipelines, it is found that cracks are often detected in the welds of heat transfer oil pipelines, and the distribution of welds containing cracks is usually typical. In this study, thermal stress theory, deflection theory, supplemented by non-destructive testing of weld defects, are used to analyze the cracks of typical pipeline welds with defects. The analysis shows that the operating temperature of this type of pipeline is high. If the fixed support is not properly set up to absorb the thermal expansion of the pipeline in sections, the pipeline will thermally expand with a large displacement, resulting in excessive thermal stress between two adjacent fixed constraint points. High; in the case of continuous change in direction and poor support, the internal stress level of the intermediate pipe section between two adjacent fixed supports is higher than that of other pipe sections due to its large elasticity and large deformation; when there is unfused , Incomplete penetration and other welding defects, obvious stress concentration will be formed due to geometric discontinuity, and the tip of the defect can easily become the source of cracks..关键词：pressure pipeline;fixed support;thermal stress;welded crack;distribution law
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发布时间：2023-06-12 - 摘要：The stainless steel sintered mesh filter element is a key component of automatic backwash filters in hydraulic, mechanical, shipbuilding, mechanical and other industries. The welding quality of its longitudinal butt weld directly affects the filtering accuracy of the filter element and the smooth operation of the automatic backwash device. It is a key link in the production process of stainless steel sintered mesh filter elements. TIG welding and special welding tools are used to weld the longitudinal weld of multi-layer stainless steel sintered mesh filter element to find reasonable welding parameters. By optical microscope, microhardness tester and energy spectrometer, the microstructure properties, solidification mode and phase composition of the weld are analyzed as well. The results show that by controlling welding heat input and improving the cooling speed of the back of the weld, the welded joint with good shape, no broken wire and no obvious defects can be obtained by TIG welding. Observing the appearance of the weld, the optimal welding current is determined to be 90~95 A. The microstructure of the weld is columnar austenite and skeleton-like ferrite, which has excellent crack propagation resistance.关键词：stainless steel sintered mesh filter element;TIG welding;welding process;weld microstructure
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发布时间：2023-06-12
Welding Technology
- 摘要：Stainless steel is widely used due to its excellent properties. The ferrite content has a very important influence on the crack sensitivity, corrosion resistance and mechanical properties of stainless steel welds. The accurate prediction of ferrite content is an important basis for guiding R&D and production. Scholars and engineers at home and abroad have carried out many studies over the years, among which Schaeffler diagrams, DeLong diagrams, and WRC diagrams have been widely used in different historical stages. Combining the principles of prediction methods, this paper compares the technical differences of different methods, analyzes the evolution process and background basis of the Schaeffler diagram, DeLong diagram, and WRC diagram ferrite prediction diagram, and summarizes the new prediction methods represented by artificial neural network prediction methods. Law principles and development status, put forward the prospect of combining ferrite prediction methods with big data and artificial intelligence.关键词：prediction methods;ferrite;stainless steel;artificial intelligence
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发布时间：2023-06-12 - 摘要：The effect of rare earth element Y on the microstructure and properties of the surfacing layer is studied by changing the amount of Y element added in the high-chromium cast iron wear-resistant alloy system, thus the microstructure of the surfacing layer has a benign transformation, so as to improve the wear resistance of the surfacing alloy. The flux-cored wire mixed gas shielded open arc surfacing method is used to make surfacing alloy on the surface of base material Q235 steel, and XRD and SEM are used to observe the microstructure of the surfacing layer and characterize the phase; by Rockwell hardness tester, wet sand rubber wheel abrasion tester conducts macroscopic hardness test, abrasion performance test, and observes the abrasion morphology to evaluate the wear resistance of the surfacing layer. The results show that the surfacing layer is mainly composed of austenite (γ-Fe), ferrite (α-Fe), M7(C,B)3, M2B phase, and adding an appropriate amount of Y element can make the hard phase distribution more uniform and the grains more fine. With the increase of the additive amount of Y element, the hardness and wear of the surfacing layer decrease first and then increase. When the additive amount of Y element is 1.6%, the hardness of the overlay layer reaches 67.5 HRC, which is 17.2 HRC higher than that without addition. The minimum wear amount is 0.864 g, and the wear mechanism is abrasive wear.关键词：rare earth;Fe-Cr-C-B surfacing alloy;hard phase;wear resistance;Y element
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发布时间：2023-06-12 - 摘要：The submerged arc welding wire and flux suitable for high manganese cryogenic steel used in LNG storage tank were developed. The C-Mn-Cr-Ni-Mo alloy system was used to design, and the Mn content in the weld metal formed is 22.5% ~ 25.5%.The weld metal has excellent mechanical properties such as tensile strength and -196 ℃ low temperature impact, and has a good match with austenitic high manganese cryogenic steel. By analyzing the influence of inter-pass temperature and heat input on the mechanical properties of deposited metal, the results show that when welding austenitic high manganese cryogenic steel, inter-pass temperature controlled and smaller heat input must be used to ensure that the weld metal has excellent comprehensive mechanical properties.关键词：high manganese cryogenic steel;-196 ℃ low temperature impact;submerged arc welding wire;welding flux;inter-pass temperature
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发布时间：2023-06-12
Welding Material
- 摘要：In view of the development demand of miniaturization and light weight of the reactor of new inverter welding power supply, and the problems such as slow current climbing and falling and poor arc following during pulse welding, a new type of reactor with magnetic core material is presented. The magnetic core of the reactor is NS ferrosilica-aluminum magnetic powder core with ring structure. According to different welding machine types and welding machine specifications, the welding requirements can be met by adding the number of ring cores or changing the number of winding. A new type of reactor can replace one open loop reactor and one closed loop reactor in series, reduce the volume and weight of the reactor by 20%, and realize the unification of the reactor core materials. Using this reactor can improve the response speed of pulse welding current climbing and falling and arc following, but will lead to the decrease of the stability of pulse peak current, so a new pulse control algorithm based on peak voltage feedback and current feedback is proposed to ensure the stability of pulse welding.关键词：power supply;welding;reactor;magnetic core;impulse control
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发布时间：2023-06-12 -
Solution and Research of Flexible Intelligent Pipe Processing Production Line for Ship Piping System
摘要：The processing of ship piping system has the typical characteristics of discrete small batch and multiple varieties. The author combined with more than 20 years of pipe processing automation equipment and production line technology research precipitation, explore to solve the discrete piping system of flexible intelligent production line processing solutions. The difficulty of intelligent production line lies in how to realize the data transmission of work order issued to the production line, how to accurately identify work order after receiving the work order, and then realize the whole process processing such as automatic feeding of pipes, automatic cutting of fixed length, automatic conveying of pipes to the next station, automatic grasping and feeding of flanges, automatic alignment and welding of pipes and flanges, automatic offline of finished products, etc. The biggest difficulty is to consider how to reflect the flexibility. Each production line needs to realize 2 or 3 types of remolding production every day. The production line needs to automatically adapt to the discrete multi-specification automatic remolding production when the work order is issued with different pipe diameters and lengths. Therefore, the intelligent piping processing production line realizes the accurate transmission of data through the production management control software (central control system) and the accurate coordination of the equipment in a wide range to solve the assembly line processing problem of this kind of discrete pipeline, improve the competitiveness of the ship in the international market to a certain extent.关键词：flexibility;intelligence;production line;pipe processing;robot- 37
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发布时间：2023-06-12 - 摘要：In the application of automatic robot welding, certain limitations exist in teaching and off-line programming. Based on the welding requirements of overlength workpiece, an automatic integrated conveyor for overlength workpiece is studied to realized the automatic transmission, welding, and unloading of workpieces; A separate pressing fixture for welding overlength workpiece is studied to solve the problem of taking out the shrinkage deformed workpieces; The application of teaching-free six-axis welding robot in overlength steel structure, multi-point and small angle welding is also studied to form a set of automatic welding workstation. This workstation integrates the vision, force, antenna and other sensors of the robot with the help of the automatic assembly line, welding robot, visual inspection, etc. Then, according to the information feedback of the sensors, the motion decision of the robot can be adjusted in real time to achieve automatic teaching-free welding.关键词：automatic welding;overlength workpiece;teaching free;weld seam tracking
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发布时间：2023-06-12 - 摘要：At present, manual welding is still the main method for all positions of pipelines in the construction stage of nuclear power plants, and there are some problems such as low welding efficiency, uneven welding quality, etc. Therefore, the popularization and use of automatic welding of pipelines has become particularly urgent. In view of above problems, an all-position TIG automatic welding system for pipelines is independently developed. Starting from the hardware system and software system, the STM32 single chip microcomputer is taken as the control core, and the communication unit of welding machine, motor drive unit and touch screen are used as the implementation carriers to complete the design of main control program, automatic welding logic program and UI interface. This system has been designed and verified, with high integration with automatic welding equipment, stable and reliable performance and simple operation. It has been widely used in nuclear engineering pipeline welding, which can effectively improve the welding efficiency and quality and reduce the procurement cost of automatic welding equipment. At the same time, this system can be applied to automatic welding of pipelines in other industries.关键词：Stm32;automatic welding;control system;nuclear power plant;pipeline
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发布时间：2023-06-12
Welding Equipment
- 摘要：Based on the 2018 edition of welder standard, the compilation principles, structural contents and quality control methods of the new edition of “National Vocational Qualification Training Course • Welder Series” are introduced, and the differences between the old and new version are compared. The new version of the course according to the “welder standard” is based on the “occupational grading system”, orientated towards “occupational activity” and centered on occupational function”. It is more modular and has a clear structure. It is a further improvement of the construction of China's welder talent system and can speed up the improvement of welders (electric welders, gas welders, brazing welders and welding equipment operators) theoretical knowledge and skill level, and provide support for standardized and scientific appraisal of welder team.关键词：course;welder standard;welder;skill level
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发布时间：2023-06-12
Welding Education
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