最新刊期
期 12 ， 2023
- 摘要：In this study, the pressureless-sintered SiC and SiC-based powder (SiC-Al2O3-Y2O3) were used as the substrate and interlayer, respectively, for joining of SiC ceramics by spark plasmas sintering. The microstructure and strength of SiC joints were investigated by means of metalloscope, scanning electron microscopy, energy spectroscopy, electron backscatter diffraction and shear test. The microstructural characterization indicated that the SiC joint exhibited a high-quality interface bonding with uniform thickness in the interlayer. The main phase compositions of the joint were β-SiC and Y-Al-Si-O-C. The fine β-SiC grains in the interlayer exhibited a random orientation. No significant β→α phase transition occurred at the joint due to the fast process of diffusion bonding by spark plasma sintering. Meanwhile, no significant stress concentration was observed at the interface because of the near-homogeneous SiC joint formed. The initial room temperature shear strength of the SiC joint was 219.9 MPa, which increased to 320.8 MPa after heat treatment in air at 800 ºC for 2 h. Further increasing the heat treatment temperature to 1300 ºC, the joint strength increased to 389.1 MPa. The joint fracture occurred mainly at the substrate with a river-like pattern, as a representative of brittle fracture. The increase of joint strength may be attributed to the interaction of Y-Al-Si-O-C and SiO2 produced during the heat treatment process, healing the defects presented in the SiC substrate such as microcracks.关键词：silicon carbide;diffusion bonding by spark plasma sintering;microstructure;shear strength
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发布时间：2024-01-24 - 摘要：The nuclear power reactor pressure vessel (RPV) is one of the core equipments in a nuclear power plant (NPP), and its safety and reliability are vital to the operation of the plant. The fabrication of RPV involves the dissimilar metal welding of low-alloy steel to austenitic stainless steel. This paper discusses the problems of organizational inhomogeneity, elemental diffusion, and stress corrosion cracking that exist in this welding. From the selection and optimization of welding filler materials, as well as the possible application of welding methods, post-weld heat treatment, process control, and other directions to discuss possible solutions to welding problems and development directions. To provide a reference for future research to improve the quality and reliability of such joints, thus ensuring the safe operation of NPPs.关键词：reactor pressure vessel;dissimilar metals welding;joint quality;research status
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发布时间：2024-01-24 - 摘要：Based on the thori-based molten salt reactor nuclear energy vessel manufacturing project, the welding process of pure nickel N02201 and N10003 Hasloy alloys was studied by using TIG. Nondestructive testing, mechanical property testing and macroscopic metallographic testing were used to verify the mechanical properties and microstructure of welded joints. At the same time, the quality control measures of pure nickel N10003 and Hastelloy N10003 welding are discussed. An ideal welding process suitable for the welding of pure nickel and Hastelloy alloy was developed. The result shows that: During welding, welding heat input and interlayer temperature should be strictly controlled. Excessive increase of welding current cannot effectively improve the fluidity of liquid metal, on the contrary, it will increase the probability of hot cracks in the weld. Attenuating current should be used to avoid arc pit crack. The microstructure of welded joint is composed of austenite and a small amount of ferrite, The weld center grain grows dendritically from the fusion zone to the weld center, A small number of carbides precipitated in the fusion zone on N02201 side, and the boundary of the fusion line on N10003 side was obvious. no defects appeared in joints; All the properties meet the relevant standards.关键词：pure nickel;hastelloy alloy;welding process;quality control
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发布时间：2024-01-24 - 摘要：Mechanical properties and microstructure of SA517 Gr.B welded joint by Submerged Arc Welding (SAW) were analyzed and investigated.The analysis results show that adopting F76A2-EG-M4 welding consumbles, matching proper welding procedure parameters,combined with process treasures of preheat before welding and heating after welding etc., the mechanical properties of welded joint exhibite excellent; the lowest microhardness is located in heated affected zone(HAZ), it indicates HAZ appears apparent softening phenomenon under the function of welding thermal cycle, which made harden quenching tendency of welded joint isn't obvious; Impact fracture feature of weld and HAZ is shearing fracture mainly, and fracture morphology has a large number of dimples, shear section ratio is 90% and 80% respectively; the main microstructure of weld is fine acicular fettite, and microstructure of HAZ is dominated by tempered sorbite, a larger number of carbide precipitated in HAZ, which results in the decrease of impact properties.关键词：SA517 Gr.B;welded joint;SAW;mechanical properties;microstructure
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发布时间：2024-01-24 - 摘要：China Nuclear Power Engineering Co., Ltd. led the research and development of a set of ACFM technology including probe, system equipment, methods and processes for the volume detection of thin-wall(≤3.5 mm) stainless steel welds in a national key engineering project.In this paper, a simulation test with different types, sizes and positions of defects was designed. ACFM and RT blind test were carried out respectively, and the test results were compared and analyzed. The verification test results show that the developed ACFM detection system and process are stable and effective, and can realize the rapid and effective detection of excessive defects in thin-wall stainless steel welds. For the super-standard defects in simulated test blocks, ACFM technology has no lower detection capability than RT. ACFM technology is sensitive to weld surface state, proper grinding does not affect the detection of defects.The research and application of high sensitivity ACFM detection provides a new idea for the detection of internal defects in welds of thin-walled non-ferromagnetic materials.关键词：alternating current field measurement;simulation verification;thin-walled austenitic stainless steel welds
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发布时间：2024-01-24 - 摘要：In order to reduce noise interference and improve detection accuracy, a wavelet soft threshold denoising method based on particle swarm optimization (PSO) for electrical signals of underwater welding was presented. Through wavelet decomposition of the signals, the signal-to-noise ratio was selected as the evaluation index, and the optimal threshold value was searched for the global iteratively to complete the signal denoising. The denoising experiments for the simulated and the measured electrical signals of underwater welding process were carried out. It is proved that the signal-to-noise ratio was improved, the root mean square error was reduced, and the detailed information of the signals can be effectively preserved after denoising by this algorithm. It is suitable for the extraction of electrical signals features of underwater welding, laying the foundation for the online monitoring of underwater welding.关键词：underwater welding;particle swarm optimization algorithm;wavelet soft threshold;electrical signal denoising
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发布时间：2024-01-24
Important Issuse
- 摘要：Aiming at the problem that BAg40CuZnCdNi, a cadmium-containing brazing filler metal used for brazing the rotor end ring and conducting bar of a certain locomotive motor, needs to be replaced by non-cadmium-containing brazing filler metal due to its inclusion in the list of prohibited substances. Cadmium free brazing filler metal BAg55ZnCuSn and SAXONIA Braze Tec h Paste-Type-FH10 were used to compare with the original cadmium containing brazing filler metal and flux QJ102. The chemical composition of the verification brazing filler metal was analyzed by chemical analysis method, the melting range of brazing filler metal was analyzed by DSC melting temperature tester (temperature rise curve method), and the flux spread and wettability of brazing filler metal were analyzed by high temperature wetting furnace. The optimal combination of cadmium-free brazing filler metal and brazing flux was determined for the process model verification of the motor rotor. The test results of the rotor model show that the brazing joint of the end ring and the conducting bar break in the heat affected zone of the conducting bar, and the mechanical properties are qualified. BAg55ZnCuSn and SAXONIA Braze Tec h Paste-Type-FH10 can be used to replace the cadmium-free brazing filler metal of the rotor of the locomotive motor.关键词：traction motor;brazing;brazing solder & flux analysis;process verification
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发布时间：2024-01-24 - 摘要：In response to the performance requirements of reducing resistance and consumption, reducing adhesion and detachment, and improving wear resistance and durability of rotary tiller blades, a method for preparing diamond-coated wear-resistant coatings is proposed. The method is compared with arc-sprayed wear-resistant welding wire coatings and plasma-sprayed WC coatings. The results show that the diamond-coated wear-resistant coating has a uniform distribution of diamonds and good bonding with the solder, fully exerting the role of the load-bearing phase. It has significantly better wear resistance than the arc-sprayed and plasma-sprayed coatings, with a weight loss of only 0.056 2 g. Field tests also show that the diamond-coated rotary tiller can sustainably cultivate an area of over 2 500 acres, which is 4.12 times and 3.13 times longer than the lifespan of the arc-sprayed and plasma-sprayed rotary tillers, respectively. Furthermore, the torque during rotary tillage is 584.66 N·m, which is 79.1% and 89.9% of the torque of the arc-sprayed and plasma-sprayed rotary tillers, respectively. The soil adhesion rate is 0.8%, which is 53.3% and 70.2% of the soil adhesion rate of the arc-sprayed and plasma-sprayed rotary tillers, respectively, demonstrating outstanding resistance reduction and anti-adhesion performance.关键词：rotary tiller blade;brazing coating;diamond;wear resistance;drag reduction;adhesion reduction
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发布时间：2024-01-24 - 摘要：Taking stainless steel resistance spot welding as an example, the influence of Cr-Zr-Cu electrode, Be-Cu electrode, W-Cu electrode on nugget offset of non-equal thickness plate resistance spot welding was analyzed. By making electrodes with the same shape, Cr-Zr-Cu electrode was used on the side of thick plate, and Cr-Zr-Cu, Be-Cu, W-Cu electrode was used on the side of thin plate. Under the premise of consistent welding parameters, nugget size and thickness and morphology was analyzed. The analysis results show that the phenomenon of nugget shift is obviously improved by using Cr-Zr-Cu electrode on the thick plate side and W-Cu electrode on the thin plate side.关键词：rail vehicle;resistance spot welding;nugget detection;electrode materials
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发布时间：2024-01-24
Welding Material
- 摘要：Defects such as deformation, porosity, cracks, incomplete penetration, etc. are easy to occur in the welding of aluminum plate on the ceiling of LNG storage tank.Especially the fillet weld between the thirteenth ring stiffener and the ceiling bottom plate. According to the design structure of the aluminum ceiling of 220 000 m3 LNG storage tank, the key points of quality control in the welding process of the aluminum ceiling are elaborated in detail: using argon gas shielded metal arc welding, the gas should be supplied in advance when starting and closing the arc, and continue to supply gas after closing the arc to prevent the molten metal from oxidation and avoid repeated arc starting at the same time; When the welding current is 160~170 A and the welding speed is 38~40 cm/min.When the wire filling speed is 38~40 cm/min and the shielding gas flow rate is 20~25 L/min, the weld of aluminum ceiling is well formed. At least two passes shall be welded at the overlapping position, and the sectional withdrawal welding or symmetrical welding method shall be adopted, and the load bearing on both sides of the pass shall be appropriately increased to achieve the purpose of controlling welding deformation. The quality control measures of aluminum ceiling welding are optimized from the aspects of "man, machine, material, method and environment".关键词：LNG storage tanks;aluminum ceiling;welding defects;welding quality
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发布时间：2024-01-24 - 摘要：This paper mainly introduces the special-shaped variable-section multi-cavity column components of Xianyang Airport Project. The steel column integral column structure of this project is mainly composed of octagon to double-supported pentagon, of which octagon and pentagon are the core supporting components of the whole, and its welding quality, assembly sequence and processing dimension accuracy are particularly important. This study analyzes the key and difficult points of octagon to pentagon fabrication from the perspective of fabrication, including the fabrication of the edge bevel of the special-shaped steel column, the fabrication process of the bending and twisting plate, the assembly process sequence of the rainwater pipe, the assembly and welding process sequence of the components, etc., to ensure the operability and structural reliability of the octagon to pentagon component fabrication. It provides certain reference value for the subsequent similar processing technology.关键词：Manufacturing accuracy;Bending and twisting forming;welding deformation;Rainwater pipe protection
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发布时间：2024-01-24 - 摘要：In this paper,welding procerure test of 6082 aluminum alloy medium plate butt joint were done using high-frequency pulse MIG welding and conventional pulse MIG welding processes with a 1 mm gap, plate thickness 8 mm, and a groove angle of 50° and 60° respectively; The macroscopic morphology of welded joints(welding appearance)and the residual stress at welding toe after welding were studied. The experimental results showed that welding appearance were better for two welding processes, compared with conventional pulse MIG welding process,high-frequency pulse MIG welding process possessed deeper penetration,wider fusion width,lower porosity sensitivity and welding residual stress. Compared with conventional pulse MIG welding process,when groove angle was 50°,at the same welding heat imput(10.7 kJ/cm),root fusion width increased about 20% by high-frequency pulse MIG welding process,about 16% when 60° groove angle.Transverse residual stress(σy) at welding toe decreased about 18.5% when groove angle was 60° by high-frequency pulse MIG welding process,about 8.5% for longitudinal residual stress(σx).When groove angle was 50°,transverse residual stress(σy) at welding toe decreased about 18% ,7% for longitudinal residual stress(σx) by high-frequency pulse MIG welding process.Decreased from 60° to 50° for groove angle ,residual stress at welding toe decreased about 6% by high-frequency pulse MIG welding.关键词：6082-T6 aluminum alloy medium plate;High frequency pulse MIG deep penetration welding;butt welding procedure;welding residual stress
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发布时间：2024-01-24 - 摘要：The effect of hybrid welding parameters on welding bead geometric dimensions has always been the focus of laser-arc hybrid welding research, so it’s inevitable to measure the dimensions of welding bead. The paper presents a new measuring system of welding bead sectional dimensions in polar coordinate system. First we can get the outline of the welding bead shape with the SOBEL edge detection algorithm . Secondly locate the center point of welding bead and make it as the original point of the polar coordinate system. Calculate the coordinates of pixels in the welding bead shape outline every other 15 degrees . According to the coordinates gainedand plotting scale, we can calculate the sectional geometric dimensions of welding bead. Comparing the dimensions measured in this paper with those measured manually, we can conclude that the measuring error can be under 3%. The research shows that the measuring methods presented in this paper can dramatically improve the efficiency to measure the dimensions and can also solve the problem that the dimensions of welding bead can notbe measured in polar coordinate system with traditional method. In conclusion this automatic measuring system has a profound meaning to the hybrid welding research.关键词：laser-arc hybrid welding;wld coss sction;SOBEL edge detection algorithm;the sectional outline of welding bead;coordinates of pixels
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发布时间：2024-01-24 - 摘要：As one of automotive lightweight materials, aluminum alloy is increasingly used in automotive parts, Friction Stir Welding (FSW) as a new type of green solid phase connection technology is favored by the industry. This article summarizes the research status of friction stir welding of aluminum alloy, which is mainly divided into traditional friction stir welding and assisted friction stir welding. The traditional friction stir welding is stated from pin shape、n/v、plunge depth and filling material. Heat energy(current、arc、laser) and ultrasonic Assisted elaborate the assisted friction stir welding.关键词：aluminum alloy;automotive lightweight;friction stir welding;mechanical property
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发布时间：2024-01-24 - 摘要：In the paper, as the object, 15 mm thick 2219 Aluminum alloy are welded by TIG with helium and argon protecting respectively, and the effect of different processes on the structure and performance of the joints are analyzed. The results show that: compared with joints welded with argon protected, the joints welded with helium protected have a larger hardness in the over-aging zone, due to the larger single-time heat input in the bottom layer. The α grains in the weld area grow, and the θ-phase increase, which increases the hardness and tensile strength of the joint, but the elongation decreases significantly. Appropriate welding speed and current can refine the crystal grains and inhibit the precipitation of the second term at the joint, thereby improving the mechanical properties of the joint.关键词：shielding gases;2219 aluminum alloy;TIG welding;microstructure;mechanical properties
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发布时间：2024-01-24 - 摘要：In this paper, ultrasonic impact treatment (UIT) technology was used to strengthen the surface of 12Cr1MoV steel welded joints in service. The changes in surface morphology, microstructure, and microhardness under different treatment parameters were analyzed. The evolution behavior of the deformed layer on the surface of the sample was compared and analyzed using transmission electron microscopy (TEM) and electron backscatter diffraction (EBSD) techniques. The results show that ultrasonic impact treatment can improve the geometric morphology of the weld toe area of 12Cr1MoV steel welded joints in service, and increase the geometric transition radius and hardness value at the weld toe. Compared to the as-received sample, when using UIT1 and UIT2 parameters, the transition radius at the weld toe increased by 108.2% and 116.4%, respectively. Correspondingly, the average hardness at the weld toe increased by 32.3% and 34.9%(within a depth of 0.1mm from the surface). In addition, it has been confirmed through experiments that ultrasonic impact treatment can introduce a gradient nanocrystalline structure layer on the surface of the welded joint of 12Cr1MoV steel in service, and the nanocrystallization of the grains is mainly achieved through dislocation slip.关键词：ultrasonic impact treatment;12Cr1MoV steel;microstructure;nanocrystal;dislocation slip
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发布时间：2024-01-24 - 摘要：On the basis of the mature automatic welding construction technology in the plain section, and in view of the characteristics of the mountainous long-distance pipeline construction, such as complex terrain, many ramps, and a large amount of elbows, this paper puts forward two research directions of automatic welding construction technology suitable for mountainous long-distance pipeline. One is to develop the process of flexible internal welding+external welding machine covering, and the other is the process of argon arc automatic root welding+external welding machine covering. At the same time, the requirements for the optimal manufacturing of equipment, pipes and hot bends are put forward.关键词：long distance pipeline in mountainous areas;automatic welding;construction technology;hot bend
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发布时间：2024-01-24 - 摘要：This paper introduces the characteristics and application difficulties of aluminum alloy spot welding process. In order to reduce the manufacturing cost of aluminum alloy spot welding, this paper designs a new method to improve the welding points after each grinding by using the compressed honeycomb mold to make the electrode surface form a specific shape, and using the compressed electrode to carry out aluminum alloy spot welding. The research results show that for the 2 mm+2 mm 6 series aluminum alloy plates, by using the electrode cap with an arc size of R100 mm on the front section, with appropriate process parameters (welding current 42.5 kA, welding pressure 6.8 kN, welding time 100 ms, and pressing pressure 7 kN), when the depth of the pressing die pit is 0.5 mm, the width between the dies is 0.4 mm, and the width of the bulge is 0.2 mm, at least 128 spot welding points can be obtained after grinding, And with the increase of the number of welding points, the strength of welding points shows an upward trend. This research provides a reference and optimization direction for the development of aluminum alloy spot welding technology in the manufacturing industry.关键词：aluminum alloy;resistance spot welding;electrode erosion;honeycomb mould;weld nugget
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发布时间：2024-01-24 - 摘要：The comprehensive quality control strategy of multi-pass welding process for automobile shock absorbers with double suspender rings with metal dust cover was studied. It mainly includes the welding of piston rod and ring, the welding of dust cover, the welding of dust cover, the welding of bottom cover and oil cylinder, and the welding between the bottom cover and ring. The study in this paper effectively solves the problem of piston rod damage during convex welding of piston rod and hanging ring, the problem of dust cover burning in the welding of carbon dioxide gas protection welding, the problem of spot welding of dust cover, the poor sealing and unqualified strength of bottom cover and oil storage cylinder, and the abnormal welding of bottom cover and hanging ring. The solution of the above quality problems plays a very important role in effectively protecting the surface quality of the piston rod in the manufacturing process and preventing the turning of the shock absorber (i.e. the suspension ring falls off), oil leakage and abnormal sound. The application results also further verify the effectiveness and feasibility of the proposed comprehensive quality control strategy for welding process.关键词：automobile shock absorber;piston rod;sling ring;bottom cover;welding quality
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发布时间：2024-01-24 - 摘要：This paper introduces the types of typical structural members in nuclear power engineering, puts forward the basic concept and content of single factor analysis method, analyzes the influencing factors affecting the welding and inspection of equipment, pipelines, valves and other components, focusing on the analysis of the root causes of welding defects and quality problems, The root causes of typical defects are analyzed from the formation mechanism of typical defects, the corresponding treatment process is formulated, and the specific treatment measures are put forward. The application of single factor analysis can effectively simplify the process, focus on the key problems, improve the analysis effect, and put forward the treatment process to solve various quality problems, so as to standardize the treatment process.关键词：nuclear power engineering;equipment pipeline;single factor analysis method;welding quality problem
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发布时间：2024-01-24
Welding Technology
- 摘要：The skill level of the welder directly determines the quality of welding products, and evaluation of the skill and operation level of the welder is usually carried out through the welder qualification examination. At present, the international welder examination standards or guidelines have different considerations for different product types and structural characteristics. At the same time, the specific contents of the standards or guidelines are different in combination with the characteristics of products or systems. Through the analysis of the international typical and widely used welder examination standards or guidelines, we can understand the differences between different welder examination standards or guidelines and their respective application scope, reasonably select welder examination standards and items, establish a complete welder training and assessment system, enhance the quality of welding products and improve the personal quality of welders, and finally ensure safe production and achieve the best economy.关键词：welder examination;standards and guidelines;classification and summary;training assessment
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发布时间：2024-01-24 - 摘要：This paper discusses how to effectively integrate ideological and political education in the vehicle engineering major of application-oriented undergraduate colleges in order to train engineering and technical talents with technical strength and social responsibility. This paper analyzes the importance of curriculum ideological and political construction, studies the educational challenges faced, and puts forward the path and suggestions. Through continuous improvement of educational methods and resource support, we can better realize the organic combination of ideological and political education and professional education, cultivate engineering and technical talents with both virtue and ability, and contribute more outstanding talents to the sustainable development of the country and society.关键词：Curriculum ideological and political;Application-oriented undergraduate colleges;Major in vehicle engineering;Engineering technical personnel
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发布时间：2024-01-24
Welding Education
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