最新刊期
期 7 ， 2022
- 摘要：In actual industrial production, the cost of obtaining weld microstructure and mechanical properties by welding test is high, so numerical simulation has become the main method to predict weld microstructure and mechanical properties.The temperature field and the material flow of friction stir welded 6061-T6 aluminum alloy are established based on SYSWELD software. The microstructure of the weld is characterized by electron backscatter diffraction. The results showed that the peak temperature and material flow rate increased with the increase of the rotation rate. The cross-section of the weld showed an asymmetrical M-shaped temperature distribution, and the temperature on the advancing side was higher than that of the retreating side. Due to the increased rotation rate, the grain size, the ratio of low-angle grain boundaries, and the shear texture intensity increased. At the same rotation rate, the grain size and the ratio of low-angle grain boundaries on the advancing side are larger than those of the retreating side. The microstructure characterization results of the weld are consistent with the simulation results of temperature and material flow.关键词：aluminum alloy;friction stir welding;temperature;materials flow;microstructure
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发布时间：2022-08-12 - 摘要：The selective laser melting process of nickel base super alloy GH4169 is simulated by finite element analysis software ABAQUS. The compilation of three-dimensional Gaussian volume heat source is realized by subroutine DFLUX. The subroutine UMATHT defines the state transition of materials, and the material parameters in different states are defined by subroutine USDFLD, the effects of phase transformation latent heat and thermal conductivity of powder solid state on the temperature field are considered. The results show that after the molten pool reaches the maximum temperature, the cooling rate is fast at first, and slows down obviously when the temperature drops to about the melting point; with the increase of the number of scanning layers, the heat will gradually accumulate, but the solid area will gradually become larger and the thermal conductivity will become larger, resulting in faster heat dissipation; the thermal stress parallel to the scanning direction is much greater than the stress perpendicular to the scanning direction; the maximum residual stress under each process parameter is basically kept at 725 MPa, the minimum residual stress along the X direction is 327.1 MPa, and the minimum residual stress along the Y direction is only 11.6 MPa.关键词：finite element analysis;selective laser melting;temperature field;stress field;residual stress
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发布时间：2022-08-12 - 摘要：In order to study whether the properties of the repairing layer can meet the work needs after laser additive repair of lCrl5Ni4Mo3N, the mechanical properties and microstructure of laser additive repair of lCrl5Ni4Mo3N was conducted. WDW-100 testing machine was used to test the tensile strength of samples. The OM and SEM were used to survey and analyze the microstructure and fracture morphology of the joints. Research indicates that the forming of the laser additive repair of lCrl5Ni4Mo3N is good. The tensile strength of 2 mm deep repairing sample can reach 92.7% of the base material, the tensile strength of 3 mm deep repairing sample can reach 89.7% of the base material. The repairing joint shows ductile fracture. Due to coarsening of second-phase particles caused by laser thermal cycle, the microhardness value of microstructure are: base material＞repairing layer＞HAZ. The metallurgical combination of repairing layer and substrate is dense. The joint consists of base material，HAZ and repairing layer. The base material is mainly composed of tempered martensite and contains retained austenite,the HAZ is mainly composed of tempered martensite and contains tempered sorbite, and the repairing layer consists of a martensite and austenite dual-phase structure.关键词：laser additive repair;lCrl5Ni4Mo3N;ductile fracture;second phase particle;microhardness
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发布时间：2022-08-12 - 摘要：Machine vision technology has been widely used in industrial measurement, industrial detection and identification because of its high precision and high automation. Several welding seam identification sensing technologies are summarized, and the basic principles and characteristics of the sensing methods are analyzed in detail. The realization steps of weld seam recognition based on machine vision are described in detail, and the corresponding filtering and elimination methods, weld feature extraction and centerline fitting methods for different noises and interferences are summarized emphatically. Based on the research of weld identification at home and abroad, several valuable research directions are put forward, including weld location based on new ranging method and its sensors, weld type identification based on convolutional neural network, 3D information reconstruction for post-welding quality inspection and weld identification under the coexistence of various interference factors.关键词：machine vision;weld recognition;visual sensor;image processing
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发布时间：2022-08-12 - 摘要：In view of the problem that the large thickness stainless steel nuclear vessel and pipeline are easy to produce corrosion defects from the inner wall and expand to the outer wall until surface leakage in the radiation environment, suitable nondestructive testing means should be used for in-service monitoring to ensure service safety. The eddy current testing method has the advantages of no additional medium, easy to realize automation, and etc., which can meet the special testing requirements of typical nuclear vessels. In order to better detect the inner wall defects of the nuclear container, a special eddy current detection device is designed, and an eddy current automatic detection system based on robot is built. By extracting the amplitude, phase, the envelope area and the maximum value of the intersection with the x-axis are used as the geometric characteristic parameters of the eddy current testing impedance diagram and the eddy current testing of simulated samples with different defect depths is carried out. The results show that: the designed experimental system can effectively respond to defects within 6mm from the upper surface; the three characteristic parameters of amplitude, envelope area and the maximum value of intersection with x-axis can well reflect the defect depth information, while the phase characteristic parameters change irregularly with the increase of depth.关键词：eddy current testing;nuclear vessel;inner wall defect;testing process
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发布时间：2022-08-12 - 摘要：The effects of polarity ratio on the stability and weld formation of high speed square wave AC TIG-MIG hybrid welding process were studied by using bead on plate welding experiment for . It is found that when the polarity ratio of TIG arc is zero, low current TIG arc is susceptible to distinguishing due to its over-elongation caused by long time mutual repulsion between TIG and MIG arcs. TIG-MIG hybrid welding process is unstable and weld formation is poor. When the polarity ratio of TIG arc is in the range of 10 ~ 40, a stable TIG-MIG hybrid welding process can be obtained under the TIG arc current of 50A, and the hump defects easy to occur in DC TIG-MIG hybrid welding can be suppressed。 When the polarity ratio is 10, the weld forming is the best. When the polarity ratio is too large, the smoothness of the weld surface decreases, the weld toe fluctuates obviously, and there are more large particle spatters.关键词：spatter;polarity ratio;weld formation;TIG-MIG hybrid welding;hump defect
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发布时间：2022-08-12
Important Issuse
- 摘要：In the manufacturing industry of various large and medium-sized generators, welding system generally rely on manual welding, so it is difficult to control the whole production process. In order to uniformly manage welding equipment, process documents, welding personnel and welding process, according to the actual situation and requirements of welding production, through adopting the intelligent information acquisition module and network technology, the existing welding management and control system is designed and innovated, and a welding information acquisition, management and control system is established based on welding power supply. Based on the functions of real-time acquisition, real-time monitoring, data storage, display, personnel management and welding equipment management for simulated and digital welding machines, the system combines welding technology, information technology, communication control and management concepts, and realizes uniform management of the welding equipments, process documents, welding personnel, welding process, welding materials, energy consumption, etc. It can effectively improve the welding efficiency, the ability of comprehensive management and guarantee the welding quality. At the same time, it provides important data support for managers with production process optimization, personnel and equipment management and resources allocation.关键词：welding power;information acquisition module;real time monitoring;unified management
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发布时间：2022-08-12 - 摘要：Taking the tracking system as the theme, this paper combs and summarizes the application status of the tracking system in narrow gap submerged arc welding, and looks forward to the technical development direction of the system in the future. This paper starts from three aspects: the significance of tracking system, the types of tracking sensors and the application of tracking system. At present, the tracking system with the most mature application and the largest market share in narrow gap submerged arc welding equipment adopts contact tracking technology. In recent years, with the continuous progress of science and technology, visual sensing technology has developed rapidly. The tracking system using this technology has been widely used in the field of welding and has made some attempts in the field of narrow gap submerged arc welding. With the continuous improvement and optimization of tracking system technology, the automation and intelligence of narrow gap submerged arc welding will be further improved.关键词：narrow gap;submerged arc;welding tracking system;welding automation
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发布时间：2022-08-12 - 摘要：The serpentine tube panel is an important part of the high-pressure steam pipeline used in the boiler field. There are a large number of welding attachments on the tube panel. At present, the welding method of the support block is manual welding, which has the problems of low efficiency, poor consistency and high working intensity. Therefore, a welding robot system is designed for the serpentine tube attachments, which can realize the whole process integrated intelligent control of automatic transmission, automatic positioning, automatic identification, and automatic flat welding and overhead welding of the serpentine tube panel. The hardware and software of the system are introduced in detail, and the operation flow of the system is designed. The welding process test is carried out by using the system, the result shows that the system runs smoothly, the laser positioning is accurate, the welding process is stable, and the flaw detection results meet the quality requirements.关键词：serpentine tube;Robot welding;automatic line;intelligent control
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发布时间：2022-08-12
Welding Equipment
- 摘要：In this work, friction plug welding of 2060-T8 Al-Li alloy was carried out with different welding force. The microstructure characteristics, second phase distribution and mechanical properties of the joints were analyzed. The results show: increasing welding force can effectively eliminate the lack of bonding defect and the hole defect. The grain size in heat affected zone increases, and severe plastic deformation occurs in thermo-mechanical affected zone and plug thermo-mechanical affected zone. Fine equiaxed crystal structures are formed between base material and plug. Compared with base material, different regions of the joint soften and the lowest hardness value is about 90 HV, which is in thermo-mechanical affected zone. When the welding force is 30 kN, the tensile strength and the elongation of the joint can reach 378.9 MPa and 5.9% respectively. And the joint coefficient is 0.746. The fracture mode of the joint is ductile fracture.关键词：Friction plug welding;2060-T8 Al-Li alloy;microstructure;mechanical properties
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发布时间：2022-08-12 - 摘要：The study and optimization of FSW process for 6082-T6 aluminum alloy via triple milling plane thread conical needle was carried out. Based on the Hexagonal Design response surface method, the mathematical model was established and the process parameters were optimized. The tensile properties of the welded joints were obvious effected by the process parameters, especially the rotation speed. The best performances of the welded no defect joints were obtained by increasing the rotation speed and welding speed appropriately. The optimal technological parameters were rotation speed 850 rpm and welding speed 650 mm/min. The triple milling plane thread conical needle can effectively promote the plastic flow of the material. The weld was well formed without obvious defects. The tensile strength of the joint reached 257.29 MPa with the elongation of 10.68%.关键词：friction stir welding;triple milling plane thread conical needle;response surface method;joint performance
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发布时间：2022-08-12 - 摘要：In this paper, the finite element analysis test of CO2 welding matching ceramic backing bottom layer welding of 10 mm thick high strength steel AH36 flat butt weld under the same heat input and different welding heat power conditions was carried out to explore the temperature field, Changes in residual stress and welding deformation, and analyze the causes of bottoming cracks. It can be seen from the analysis that during the bottom welding, the residual stress value generated during the cooling and shrinkage of the molten pool metal is between the yield strength and the tensile strength of the plate, and the irreversible welding deformation of the plate occurs, and there is uncertainty about the occurrence of bottom cracks. The welding heat power is large, the temperature of the molten pool is high, the cooling rate is fast, and the stress concentration area of the weld increases; Further increase, the underlying weld is prone to hot cracks.关键词：backing weld;temperature field;residual stress;welding deformation
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发布时间：2022-08-12 - 摘要：Gas metal arc welding (GMAW) surfacing test was carried out on the 15CrMoG membrane water-wall by using ErNiCrMo-3 AMS alloy Inconel625 wire. The influence of welding current and welding gun swing frequency on the surface forming of surfacing layer was studied. The evolution of microstructure of surfacing layer was analyzed and its microhardness was tested. The results show that the welding current mainly affects the width and surface oxidation degree of the surfacing layer, and the swing frequency of the welding gun mainly affects the fineness degree of the fish-scale grain on the surface of surfacing layer, when the welding current is 180 A and the swing frequency of the welding gun is 10 Hz, a well-formed surfacing layer can be obtained. The evolution of microstructure of surfacing layer from bottom to top is as follows: planar crystal → columnar cellular crystal → dendritic crystal → equiaxed crystal. As the heat dissipation direction changes from perpendicular to the fusion line to parallel to the fusion line, some transverse microstructure appears on the top of surfacing layer. The microhardness of the surfacing layer increases from the substrate along the direction perpendicular to the fusion line, and the microhardness of the surface is evenly distributed, and the average microhardness is 270.6 HV.关键词：membrane water-wall;Inconel625 alloy;forming technology;microstructure, microhardness
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发布时间：2022-08-12 - 摘要：The aluminum alloy shell (5A06 H112, inner diameter Φ2 110
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发布时间：2022-08-12 - 摘要：The plunge force of 6061-T6 aluminum alloy refill friction stir spot welding was measured through experiments. The variation law of plunge force during welding and the effect of different process parameters on plunge force was studied. The experimental results show that the plunge force first increases and then decreases during the plunging process. The plunge force is closely related to the frictional heat generated in the welding process. The higher the rotation speed of the stirring head, the smaller the plunge speed, the more friction heat production, the higher the thermoplastic degree of the welded material, and the smaller the plunge force required. Within the range of selected process parameters, the "cold condition" of low speed (900 r/min) and large plunge speed (100 mm/min) is used, and the maximum plunge force is 12.63 kN; Use the "hot condition" of high speed (1 700 r/min) and small plunge speed (20 mm/min),the maximum plunge force is 3.2 kN.The plunge depth has little effect on the maximum plunge force .关键词：refill friction stir spot welding;process parameters;plunge force;aluminum alloy
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发布时间：2022-08-12 - 摘要：As the key part of rail transit train, pillow beam is the platform connecting the train body and bogie. It should not only bear the weight of the vehicle, but also bear and transfer the vertical force, longitudinal force and transverse force between the bogie and the car body. At the same time, the pillow beam is also the additional air chamber of the air spring. Its manufacturing process, process methods and the precision of the key parts of the size control directly affect the manufacturing quality of the vehicle. This paper briefly summarizes the corbel manufacturing process, and connecting with the actual production experience, has carried on the induction summary to related issues discussed quickly reach the EMU corbel manufacturing process and matters needing attention, and the common problems in the corresponding solution measures are put forward, so as to achieve the purpose of controlling the overall size and quality of the pillow beam after welding. It provides useful reference for the production and manufacture of pillow beam in the following market.关键词：pillow Beam;welding deformation;quality control;compand process
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发布时间：2022-08-12 - 摘要：SA-533GrBCL1 steel is a kind of steel that is widely used in the construction of nuclear power plants. It has certain nuclear safety requirements to verify the welding stability of SA-533GrBCL1. Specially carry out research on the influence of electrode arc welding multiple repairs on the performance of steel plate SA-533GrBCL1 for pressure vessels. Through performance tests such as tensile, bending, low temperature impact and hardness tests, the different welding joints of multiple repairs (≤5 times) are analyzed. The metallographic structure distribution and variation law of the location. The results show that the mechanical properties of SA-533GrBCL1 welded joints have not changed abnormally after repeated repairs or post-weld heat treatment, and the performance indicators meet the requirements of relevant manufacturing specifications, but the heat-affected zone exists after repeated repairs compared with unrepaired joints. Softening, post-weld heat treatment degrades and smoothes out hardness differences in various areas of the welded joint. Microscopically, the weld metal and the fusion zone of the post-weld heat treatment show that the ferrite structure initiates acicular, block, and flake morphology transformation, and is accompanied by a small amount of granular bainite and pearlite structure, showing that the impact toughness value is dispersive.关键词：SA-533BCL1;multiple repairs;mechanical properties;metallographic structure
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发布时间：2022-08-12
Welding Technology
- 摘要：In recent years, the welding process stability of welding materials has received extensive attention. The processability of welding material is generally evaluated by experience without objective basis. Therefore, comprehensive quantitative evaluation of welding wire weld bead quality is of great significance to the designers, welding materials development units and manufacturers. Based on the Fuzzy Analytical Hierarchy Process (FAHP) method, a comprehensive evaluation system is established for the weld bead quality of stainless steel welding wire, including three first-grade index of weld bead size, bead color and bead straightness, and corresponding second-grade and third-grade evaluation index are also established. The weight determination focuses on forming stability, and the priority relationship matrix is established. The priority relationship matrix is transformed into a fuzzy consistent matrix with additive consistency, and the weight vectors of each index are calculated. Relying on the TS fuzzy and according to the scope of the bottom layer sampling model, the membership function is determined, and the sampled data is calculated layer by layer, and finally a comprehensive quantitative evaluation is realized. The model is tested and verified by design tests, and the evaluation results are tested for the validity of the maximum membership principle. The result shows that the bead forming quality of the four manufacturers is ranked 2#, 3#, 1#, 4# in descending order of "excellent + good".关键词：fuzzy analytic hierarchy process;stainless steel welding wire;quantitative evaluation;forming quality
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发布时间：2022-08-12 - 摘要：The welded joints of domestic ER 5356 and ER 5087 aluminum alloy wires were carried out with salt spray corrosion test for 0~1 000 hours, the test periods were 100 h, 250 h, 500 h, 750 h and 1 000 h. The mass method and standard number were used for assessment, and the microstructures of weld, heat affected zone (HAZ) and parent material of these two kinds of welded joints after the neutral salt spray corrosion test were observed by the scanning electron microscope (SEM). The results show that when the corrosion time is short, the weight loss rate rises sharply. When the corrosion time is 100 h, the weight loss rate reaches its maximum. As the corrosion time continues to extend, the weight loss rate gradually reduces. When the corrosion time is over 750 h, the weight loss rate tends to stabilize. The average weight loss rates of domestic ER 5356 and ER 5087 aluminum alloy wires are 0.005 1~0.018 6 g/m2h and 0.005 0~0.010 3 g/ m2h respectively, both corrosion surfaces reache 9.5 grade or above. The microstructures of the weld, HAZ and base material of these two kinds of welded joints change little.关键词：ER 5356 aluminum alloy welding wire;ER 5087 aluminum alloy welding wire;salt spray corrosion;microstructure
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发布时间：2022-08-12
Welding Material
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