最新刊期
期 10 ， 2022
- 摘要：In order to expand the application of laser-MIG hybrid welding in the manufacturing of aluminum alloy car body profiles for high-speed train, laser-MIG hybrid welding experiments were carried out to weld typical joint structure of traditional 3 mm thick A6N01S-T5 aluminum alloy for high speed train in this work. The welding parameters were optimized, structure and property of joints were analyzed. The adaptability of the laser-MIG hybrid welding was also studied. The experimental results show that the weld is well formed and no porosity defects with the optimal welding parameters. The microstructure in the weld center is dendritic as cast structure, and near the bond line is columnar crystal structure. The bond zone is narrow, but the grain is slightly coarse in the heat-affected zone. The hardness of weld metal zone is lower than that of the base metal zone, and the minimum hardness is located in the heat-affected zone near the bond line. The average tensile strength of the joints with the optimal welding parameters is 204.6 MPa, reaching 83.5% of the base metal. The tensile sample fractures near the bond line and the fracture morphology showes typical plastic fracture characteristics. And the joint has good bending performance. The optimal welding parameters has good commonality when the assembled gap less than 1.0 mm, the weld formation and joint tensile strength are fine. The weld formation and joint tensile strength are still good with the optimized welding parameters when the assembled gap increases to 1.5 mm. The research results prove that the laser-MIG hybrid welding has good feasibility and adaptability in typical joints of aluminum alloy carbody for high speed train.关键词：aluminum alloy;laser-MIG hybrid welding;weld formation;porosity defects;microstructure properties
- 223
- |
- 37
- |
- 0
发布时间：2022-10-24 - 摘要：MIG welding is a primary joining process for car body structure of aluminum alloy involved in the electric cars, but there are some problems such as joint softening and great tendency to form pores in the weld, which brings severe challenges to the quality control of aluminum alloy car body structure welding. Acting as an external excitation, mechanical vibration was introduced into the MIG welding process of aluminum alloy to improve the quality of welded joint. The microstructure of the welded joint was observed by optical microscope and scanning electron microscope. The grain sizes of weld and heat affected zone were determined by electron backscatter diffractometer. The number of pores in the weld was detected by X-ray detector. The microhardness of joints was tested by a Vickers-type microhardness tester. The tensile test at room temperature was carried out on electronic universal testing machine to study the effect of vibration frequency on weld appearance, pore distribution, microstructure and mechanical properties. The results show that mechanical vibration can effectively refine the grains of the weld, reduce the number of pores in the weld, increase the penetration, and improve the strength and hardness of the joint. In addition, as the vibration frequency increases, the grain size of the weld and the number of pores in the weld gradually decrease, the penetration, tensile strength and hardness of the joint continuously increase.关键词：mechanical vibration;aluminum alloy;MIG welding;microstructure;pore
- 107
- |
- 16
- |
- 0
发布时间：2022-10-24 - 摘要：In order to study the law of welding seam formation and the process of defect formation during the composite penetration welding of ten thousand watts fiber laser-arc, the test takes 20 mm thick Q235 low carbon steel as the research object, adopts the flat welding method, and studies the forming characteristics of the front and back of the weld under the conditions of different laser power, welding speed and welding current. The flow changes of the backside molten pool, the formation of welding nodulations and spatter were observed and analyzed by high-speed camera. The results show that it is difficult to get a good weld shape by the change of laser power, welding speed or welding current alone, and the weld is prone to front sag, back weld tumor and spatter. The formation of welding tumor and a large number of spatter on the back side is an important reason for the front sag of the weld. The unstable laser penetration leads to the large fluctuation of the metal vapor recoil force on the molten metal liquid, which is one of the important reasons for the formation of welding tumor and spatter on the back side.关键词：ten thousand watts;Fiber laser-arc composite welding;one-side welding with back formation;defects
- 95
- |
- 21
- |
- 0
发布时间：2022-10-24 - 摘要：Aiming at the technical problems of short service life and frequent replacement of the rotary blades, the research on the wear-resistance strengthening process of the rotary blades was carried out. The 35%WC coating was prepared on 65Mn steel by plasma cladding and induction brazing respectively. The results show that compared with the plasma cladding 35%WC coating, the wear resistance of the induction brazing 35%WC coating is improved by 1.5 times, the distribution of hard particles is more uniform, and the burning loss is less. On the basis of the above research, the wear-resistance of the diamond coating developed by induction brazing is more than 5 times higher than that of 35%WC coating, and the brazing time of the induction brazed diamond coating of the rotary blades is further optimized. When the brazing time is 25 s, the coating has good formability, and the deformation of the rotary blade body is small. Field tests have verified that its service life is more than 4 times higher than that of the original rotary blades. The induction brazing diamond technology has been popularized and applied to agricultural machinery tools such as plow tips and crushing knives. Its service life is generally increased by more than 3 times, and is applied to overflow parts of construction machinery such as the middle slot of scraper conveyor and spiral conveyor, it can significantly reduce wear and energy consumption.关键词：induction brazing;plasma cladding;wear-resistant strengthen;rotary blades;diamond coating
- 64
- |
- 12
- |
- 0
发布时间：2022-10-24 - 摘要：Aiming at the transformation and transformation of thermal power boiler units, JW309HN flux-cored welding wire with high temperature resistance is developed, mainly by adjusting the Cr、Ni、C and N contents in the deposited metal of the flux-cored welding wire, and designing the optimal alloy composition and ferrite content to solve the problem of ferrite. After the austenitic stainless steel is heated or stayed in the range of 500~800 ℃, the σ brittle phase is precipitated in the deposited metal, which leads to the reduction of its toughness and plasticity. The four kinds of flux cored wires were welded by CO2 gas shielded welding. The chemical composition, tensile strength, impact toughness, metallographic structure and X-ray diffraction of the deposited metal are tested and analyzed. The test results show that the 2# (3#) JW309HN flux-cored wire is controlled to have a ferrite content of about 6.0 FN, with good welding processability and the weld metal contains a certain amount of ferrite to avoid welding cracks; and the deposited metal has good mechanical properties under the heat treatment of 750 ℃×1.5 h，which meets the relevant technical requirements.关键词：PWHT;high temperature resistant stainless steel flux cored wire;σ brittle phase;ferrite content;thermal power unit
- 76
- |
- 13
- |
- 0
发布时间：2022-10-24 - 摘要：To verify the feasibility of laser additive repair technology in the application of high-speed rolling stock axle damage repair, this paper carried out experiments on the relevant laser repair process on the axle substrate, focusing on the influence of laser power and scanning speed on the melt quality, designing different parameter combinations to improve the melt layer morphology during the melting process, and obtaining melt specimens with good surface forming condition respectively. By analyzing and studying the macroscopic cladding morphology, macroscopic metallographic analysis, microhardness, metallographic organization, etc., and the better process parameters were selected, and further mechanical properties such as tensile properties, impact properties, stress corrosion, and fatigue tests were performed on the clad specimens. The result show that, when the optimized process parameters are used to laser cladding IN625 nickel base powder on EA4T, the tensile properties of the cladding specimen are better than the standard requirements of the base material, impact properties better than the impact properties of the base material, and fatigue life comparable to that of the base material, meeting the requirements of the axle service performance, which can be used for the subsequent repair of EA4T axles of high-speed rolling stock.关键词：laser additive repair;EA4T axle;microstructure;mechanical property
- 97
- |
- 11
- |
- 0
发布时间：2022-10-24 - 摘要：Because of its excellent high temperature wear resistance and oxidation resistance, Stellite alloy is widely used in the nuclear pumps, valves, steam turbine, and other products, but it is the strategic resources, expensive, and easily activate into intense radiation elements. Use the independent development of Ni3Al surfacing welding wire, and compare welding manufacturability and performance with the commonly used Stellite6 powder. Especially for the two commonly used heat treatment regimes of 650 ℃×4 h and 870 ℃×4 h, the microstructure and property changes of the two kinds of surfacing layer were studied. It is found that both Ni3Al wire and Stellite6 powder have good welding performance when surfacing on 304 austenitic stainless steel. The hardness of Ni3Al surfacing layer is higher than that of Stellite 6 alloy. With the increase of heat treatment temperature from 650 ℃ to 870 ℃, the hardness of Ni3Al surfacing layer decreased, while that of Stellite6 surfacing layer increased. After heat treatment at 870 ℃×4h, the hardness of Ni3Al surfacing layer was still 68 HV2 higher than that of Stellite 6 surfacing layer which has a good reference value for the subsequent engineering application of the material.关键词：wear resistance surfacing;Ni3Al surfacing layer;Stellite6 surfacing layer;instead of Co-based materials
- 57
- |
- 13
- |
- 0
发布时间：2022-10-24 - 摘要：On account of the defects such as welding deformation, unqualified penetration and large porosity tendency in aluminum alloy battery trays welding, the 2.5 mm thickness 6061 aluminum alloy plate is taken as the research object. Based on the CMT Mix process from Fronius, the effects of shielding gas, Arclength correction and dynamic correction on the inner pore, penetration and weld width were studied. The results showe that the CMT Mix combines the characteristics of CMT short-circuit transfer and pulse transfer, the weld surface is well formed, the penetration is qualified, and the welding process has less spatter, the inner pores are well controlled, the welded joint is corresponding to the criterion of T/CWAN 0027—2022 battery tray weld manufacturing. Compared with pure Ar shielding gas, the protection effect of Ar+30%He is better, the pore number and size are more significantly reduced. When the Arclength correction is negative, the penetration of the weld increases, while the number and size of the pores inside the weld significantly reduce; when the dynamic correction is negative, the penetration and the size of the pores inside the weld obviously increase. Compared to the Arclength correction,the dynamic correction has a more obvious effect on the penetration than that of Arclength correction.关键词：CMT Mix;arclength correction;dynamic correction;porosity tendency;battery tray
- 94
- |
- 23
- |
- 0
发布时间：2022-10-24 - 摘要：The surface nano-treatment of 7075-T651 aluminum alloy was realized by surface mechanical rolling treatment (SMRT) method. Electron backscatter diffraction (EBSD) results show that a 500 μm thick gradient nano-layer is formed on the surface of SMRT sample, the thickness of the surface nano-crystal layer is about 50 μm and the average grain size is about 200 nm. The thickness of the subsurface deformation grain layer is about 450 μm, and the average grain size is about 2 µm. The base metal shows typical rolling grain characteristics, and the average grain size is about 5 µm. The tensile test results show that the tensile strength, yield strength and elongation of the original 7075-T651 aluminum alloy are 545 MPa, 506 MPa and 17.3% respectively. After SMRT, the tensile strength, yield strength and elongation are 620 MPa, 536 MPa and 13.4% respectively. The strength of the sample significantly improves, and the toughness does not significantly decrease. Gradient nanostructures are introduced into the surface layer of the material by SMRT. This special structure has excellent matching of strength and plasticity, which is the main reason for the improvement of mechanical properties.关键词：7075 aluminum alloy;gradient nanostructure;surface mechanical rolling treatment;surface nano-treatment
- 55
- |
- 6
- |
- 0
发布时间：2022-10-24 - 摘要：The metallographic, tensile, bending, hardness and fatigue properties of the high-speed rail connection plate welded joint of friction stir welding and fusion welding were compared and studied.The results show that both welding methods are qualified in metallography;The tensile strength of the joint of friction stir welding is 275.67 MPa and is about 4.5% higher than that of fusion welding, which is 263.8MPa; The bending property of friction stir welding joint is all qualified at 180°, and the crack occurs in the specimen of fusion welding head bending at about 110° due to the existence of pores;The hardness distribution of friction stir welding joint is similar to W shape, the microhardness value of the nugget zone of the central layer is about 79~104 HV, and the softening phenomenon occurs at -18~-6 mm and 6~18 mm, and the lowest hardness is 69 HV;The microhardness value of the weld zone on the central layer of the fusion welding joint is about 92~97 HV, the softening phenomenon occurs at about 3~9 mm, and the lowest hardness is 71 HV;The median fatigue limit of friction stir welding joint is 137 MPa and is about 17% higher than that of fusion welding, which is 117 MPa.关键词：6082-T6 aluminum alloy;friction stir welding;fusion welding;microhardness;fatigue performance
- 61
- |
- 33
- |
- 0
发布时间：2022-10-24 - 摘要：To reduce the ratio of weight to volume and realize the lightweight, the welding technology under the “Double carbon”target has put forward higher application requirements.In this paper, the application of high efficiency deep penetration Argon arc welding technology in strain-strengthened vessel is studied, the changes of strength, fracture morphology, plasticity, toughness, microstructure, grain size and slag inclusion of the welded joint of domestic austenitic stainless steel S30408 welded by K-TIG process under 0% pre-stretched, welding seam specimen made from the product welding test plate after pre-stretched by stress control method and the specimen made from the strain-strengthened vessels were analyzed and compared. The results show that welding joint quality is stable, the weld appearance is beautiful, and the production efficiency is greatly improved. The properties of the samples under different conditions of A,B and C all meet the standard requirements. After strain strengthening, the yield strength increases significantly, which stimulates the plasticity reserve, effectively improves the ratio of yield to strength, and brings into full play the bearing capacity of the material to a greater extent, thus increasing the practical allowable stress of the material, it can be used in the manufacture of low temperature pressure vessel.关键词：K-TIG;strain-strengthening;S30408 austenitic stainless steel;pressure vessel;lightweight
- 66
- |
- 14
- |
- 0
发布时间：2022-10-24 - 摘要：There is no anti-slip brackets in the construction design of the VVER-1000 main coolant piping. Taking into account the nuclear safety of LBB, according to the requirements of NNSA, the nuclear safety level of the main pipeline has been increased from the originally designed Class B equipment to the Class A equipment management.Based on the regulations and the welding procedure qualification (WPQ) instruction (ППА) which were provided by Russian, an additional impact toughness requirement was added in the inspection items. The primary WPQ was failed because of part of impact values was too low in WPQ with 5G1T welding position.The article is focus on welding parameters,test values, welding materials, heat input etc. influence factors in WPQ with horizontal fixed position of pearlite heat-resistant steel, enhance of research through theory aspect.The relevant influencing factors were analyzed and demonstrated, and finally passed the process qualification test and verification, and the welding process qualification task was successfully completed. The actual application in the main coolant piping of the 3 and 4 units of a nuclear power plant has achieved good results. It has reference and promotion value for subsequent welding of the main coolant piping of similar type of nuclear power units and other similar pearlite piping with grand diameter and wall thickness.关键词：main coolant piping;procedure qualification;Pearlitic heat-resistant steel;welding heat input;impact toughness
- 77
- |
- 29
- |
- 0
发布时间：2022-10-24 - 摘要：N08810 alloy is the main base material for polycrystalline equipment, and the matching welding material E2133Mn covered electrode is developed in this paper. The welding metal is tested by room temperature tensile test, 600 ℃ high temperature tensile test and G28-A corrosion test. It is proved that the welding metal has excellent mechanical properties and corrosion resistance. In order to verify the matching of E2133Mn electrode and base metal and meet the actual engineering needs, this electrode is used for butt welding of N08810 steel, and the properties of welded joints are tested. The welded joint passed the X-ray flaw detection and bending test, the test shows that the welded joint has no welding defects and good toughness. All the welded joints of E2133Mn fracture in the base metal in tensile test, there is no obvious difference in the strength of each position of double V groove. The tensile strength of as-welded reaches 560 MPa, and after stabilization treatment, the tensile strength increases to 620 MPa. Although the tensile strength at high temperature has obviously decreased, it is superior to the base metal and also meets the design requirements. The test results show that the developed E2133Mn electrode has excellent matching with N08810 steel, and its tensile strengths of the weld and heat affected zone at room temperature and high temperature are better than those of the base metal. The performance of the welded joint fully meets the actual engineering requirements, which provides a theoretical reference for polysilicon equipment manufacturing.关键词：photovoltaic industry;polysilicon;cold hydrogenation reactor;tensile strength at high temperature;E2133Mn electrode
- 68
- |
- 12
- |
- 0
发布时间：2022-10-24 - 摘要：Tip dressing quality control is a problem that plagues automated body-in-white production lines. Tip dressing in automatic mode, and if the status is not good and cannot be found in time, it will often cause batch quality issues. In this paper, the resistance data before and after tip dressing is obtained through the communication between server, web terminal and welding controller. Statistically classify the resistance data on web terminal, and set the tolerance for the resistance independently before and after each welding gun tip dressing. Effectively monitor problems such as poor grinding, dirty tip, and tip overheating during the welding process. Find problems through digital method, and investigate and solve problems on site, which greatly reduces the occurrence of batch welding quality problems. It is successful application that combine the digitalized control of the welding process and on-site problem solving.关键词：spot welding;tip dressing digitalizing;welding quality;big data
- 60
- |
- 12
- |
- 0
发布时间：2022-10-24 - 摘要：The local cracking of individual sealing fillet welds between stainless steel pressure tube and stainless steel sealing sleeves is analyzed and researched. The cracks are found in the blowing purge test after the installation of the RH finishing reheater in an ultra supercritical power plant boiler unit. A series of scientific experiments, including chemical analysis, mechanical properties, metallographic structure, SEM fracture analysis are carried out to confirm that the crack starts at the irregular toe of the fillet weld and extends from the outer wall to the inner wall after painting. Therefore, it is concluded that the reason for this kind of crack may be that the uneven forming part of the toe of the fillet weld occasionally and instantaneously bears excessive external load to damage, which is consistent with the results of on-site appearance inspection, and the corresponding improvement measures are formulated to effectively ensure the quality, performance and safety of products, and provide reference for the subsequent manufacture of similar products.关键词：ultra supercritical power plant boiler unit;pressure tube;sealing sleeve;fillet;crack
- 84
- |
- 15
- |
- 0
发布时间：2022-10-24 - 摘要：The influence of the main process parameters on the bulging region of high-strength steel in narrow gap laser welding with filler wire was studied. By measuring the width Wmax of the weld bulging region and its distance d from the weld surface under different process conditions, the relationship between the main welding parameters and the bulging region size was established. The research results show that the ratio of the energy absorbed by the welding wire to the base metal is the main factor affecting the width and position of the bulging region. Reducing the laser power, increasing the welding speed and wire feeding can reduce the bulging region. The process range of different bulging angles β<30° and >60° is further proposed, and reducing the bulging angle β is an effective method to obtain solidification-free crack-free welds under the condition of large aspect ratio.关键词：narrow gap laser welding;high-strength steel;solidification cracking;bulging region
- 65
- |
- 16
- |
- 0
发布时间：2022-10-24 - 摘要：By using the specially developed multi-station friction welding equipment for embedded parts, the orthogonal test, welding procedure qualification, batch test and simulation test were respectively used to carry out a series of process research for embedded parts of typical specifications of nuclear power reinforcement steel. The results show that the upset dimension is an important variable affecting the tensile strength of the friction welding joint of embedded steel bars. The factors influencing the upset dimension are secondary friction pressure, secondary friction pressure, secondary friction time and rotational speed in descending order. The qualified friction welding parameters are obtained for five typical steel bars of
- 76
- |
- 8
- |
- 0
发布时间：2022-10-24
Important Issuse
- Postal code：610051
- Tel：028-83289008
- Technical support is provided by Beijing Founder electronics co., LTD 蜀ICP备07004068号-2
公网安备11010802024621 - It is recommended to read the content of this site in Chrome&IE9+. Please switch to extreme mode in browser 360.
- Cookies We use cookies to help provide and enhance our service and tailor content. By continuing, you agree to the use of cookies.
0