共查询到20条相似文献,搜索用时 31 毫秒
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To improve the welding efficiency of conventional arc welding, triple-electrode fillet welding was proposed and developed. Stability of triple-electrode fillet welding process is the assurance for ideal joint. The evaluation model for arc fluctuations of triple-electrode fillet welding was established based on the characteristic parameters and their variation coefficients. This model indicated that variation coefficients could reflect arc voltage flnctuations of welding process, and its analysis result was consistent with the actual welding process. 相似文献
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Prediction of welding residual stress in multipass narrow gap welded pipes with large thickness 下载免费PDF全文
The objective of this study is to investigate the influence of post weld heat treatment (PWHT) on the distribution of residual stress in welded pipes with large thickness. The detailed pass-by-pass finite element simulation was developed to study the residual stress in narrow gap multipass welding of pipes with a wall thickness of 150 mm and 89 weld beads. The effect of PWHT on welding residual stress was also investigated by means of numerical analysis. The simulated results show that the hoop stress is tensile stress in the weld region and compressive stress in the parent metal areas adjacent to weld seam. After heat treatment, the residual stresses decrease substantially, and the simulated residual stress is validated by the experimental one. The distribution of the through-wall axial residual stress along the weld center line is a self-equilibrating type. 相似文献
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Development of Ag-Cu-Zn-Sn brazing filler metals with a 10 weight-% reduction of silver and same liquidus temperature 下载免费PDF全文
With BrazeTec BlueBraze the manufacturers in HVACR industry have an alternative filler metal with 10 weight-% less silver but same brazing temperatures. The performance of these new alloys has been evaluated in several tests. The evaluation included wetting investigations, metallographic examinations, joint strength at different temperatures and pulsation and corrosion resistance. The results of these tests will be presented in this paper. 相似文献
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采用有限元数值模拟方法研究了冷却过程在Al Al2 O3 异种材料结构件钎缝处导致的剪切应力分布。计算结果表明 :最大剪切应力位于钎缝圆角处和靠近钎缝圆角的Al2 O3 陶瓷 /Cu镀层金属界面处 ,同时中间层合金的热膨胀系数与Al的热膨胀系数相匹配时 ,可以最大限度减小剪切应力 相似文献
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Effect of Zr-Ti combined deoxidation on impact toughness of coarse-grained heat-affected zone with high heat input welding 下载免费PDF全文
In this study, the effects of Zr-Ti combined deoxidation and AI deoxidation on the impact toughness of coarse- grained heat-affected zone in high-strength low-alloy steels were investigated. More fine oxides were formed in the Zr-Ti-killed steel than in Al-killed steel. It was also found that more acicular ferrite grains were formed in the coarse-grained heat-affected zone in the Zr-Ti-killed steel than in Al-killed steel. The impact toughness of coarse-grained heat-affected zone of Zr-Ti-kiUed steel was higher than that of Al-killed steel. The good impact toughness was attributable to the pinning effect of fine oxides and the formation of acicular ferrite grains on fine oxides. 相似文献
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TIG welding-brazing process with high frequency induction hot wire technology was presented to create joints between 5A06 aluminum alloy and SUS32! stainless steel using ER1100 filler wire with different temperature. The joints were evaluated by mechanical test and microstructural analyses. The welding procedure using hot fiUer wire (400 ℃ ) significantly increases strength stability by 71% and average value of tensile strength by 30. 8 % of the joints, compared with cold wire. The research of microstructures in interfaces and welded seams reveals that using 400 ℃ hot filler wire can decrease the thickness of intermetallic compounds ( IMCs ) from 6 to 3.5 txm approximately, which is the main reason of mechanical property improvement. 相似文献
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Cockcrofi-Latham fracture criterion was applied to predict the fracture of high strength steels. A Marciniak-type biaxial stretching test of the four classes of high strength steels was carried out to measure the material damage limit of Cockcrofi-Latham fracture criterion. Furthermore, in order to improve the simulation accuracy, the local anisotropic parameters depending on the plastic strain (strain dependent model of anisotropy ) were measured by digital image correlation method and incorporated into Hill' s anisotropic yield condition by authors. To confirm the validity of Cockcrofi-Latham fracture criterion, the uniaxial tensile tests based on JIS No. 5 tensile specimen were performed. The force-displacement history and fracture happening strokes were predicted with high accuracy. Then, Cockcrofi-Latham fracture criterion was applied to predict the failure of four types of spot welded joints. To simulate the local bending and warping deformations around the heataffected zone, the discrete Kirchhoff triangle element was adapted. FEM results for four classes of high strength steels and four types of spot welded joints had a good correlation with experimental ones. 相似文献
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Welding deformation control of medium-thickness structures made by advanced high strength steel 下载免费PDF全文
In order to investigate the residual angular deformation in fillet welding of T-joint of HG785 high strength steel with a medium thickness plate, both detailed thermo-mechanical finite element simulation and conventional gas metal arc welding experiment were carried out in the present study. In-process deformation control method using backheating method to reduce the residual deformation was discussed. 相似文献
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All-position welding is an important technology in energy sources, chemical, shipbuilding and other industries. When welding current is larger than 200 A, the molten metal tends to flow down due to the force of gravity. In order to "push" the molten metal into the weld, a new kind of U-frame excitation model, which could produce electromagnetic force to balance the gravity of the molten pool, was designed. The related parameters of the excitation model were simulated by Maxwell 3D, and the relationships between the parameters and the magnetic induction intensity were analyzed. Finally, the electromagnetic force in the molten pool was calculated, and the appropriate parameters of the U-frame excitation model were determined. The results of the simulation verify the feasibility of the all-position welding excitation model. 相似文献
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Effect of variable polarity frequency on 2A14-T6 aluminum alloy welds using HPVP-GTAW process 下载免费PDF全文
Hybrid ultrahigh frequency pulse variable polarity gas tungsten arc welding (HPVP-GTAW) for 2A14-T6 high strength aluminum alloy was carried out and the effects of variable polarity frequency with constant pulse current frequency 40 kHz on weld bead geometry, microstrueture and microhardness were analyzed. Experimental results indicate that, compared to that of the conventional VP-GTAW process, the weld depth and ratio of weld depth to width are improved significantly by the variable polarity frequency in the HPVP-GTAW process, which the ratio of weld depth to width is improved by 36% at equal variable polarity frequency of 100 Hz, and improved by 55% with that of 200 Hz. Weld microstructure and microhardness distribution are changed obviously with the increase of variable polarity frequency. In the conventional VP-GTA W process, the grains in weld central zone are coarser, and the microhardness in weld central zone and fusion zone is about 95 HV and the lowest 82 HV, respectively. The microhardness is enhanced to a certain extent both in the weld central zone and fusion zone with the variation of variable polarity frequency in the HPVP-GTAW process due to the refinement and uniformity of weld microstructure. With the variable polarity frequency of 600 Hz, the microhardness in weld central zone and fusion zone reaches nearly 110 HV and 97 HV, respectively. 相似文献
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Split Hopkinson pressure bar test system was used to investigate the plastic deformation behavior and dynamic response character of a-type Ti–5Al–2.5Sn ELI and near a-type Ti–8Al–1Mo–1V titanium alloy when subjected to dynamic loading. In the present work, stress–strain curves at strain rate from 1.5 9 103to 5.0 9 103s-1were analyzed, and optical microscope(OM) was used to reveal adiabatic shearing behavior of recovered samples. Results show that both the two alloys manifest significant strain hardening effects. Critical damage strain rate of the two alloys is about 4.3 9 103s-1, under which the impact absorbs energy of Ti–5Al–2.5Sn ELI and Ti–8Al–1Mo–1V are 560 and 470 MJ m-3, respectively. Both of them fracture along the maximum shearing strength orientation, an angle of 45° to the compression axis. No adiabatic shear band(ASB) is found in Ti–5Al–2.5Sn ELI alloy, whereas several ASBs with different widths exist without regular direction in Ti–8Al–1Mo–1V alloy. 相似文献
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D.A. Chinakhov 《中国焊接》2014,23(3):26-30
Gas dynamic control in welding with consumable electrode in conditions of two-jet gas shielding and its impact on the processes in the welding area and properties of the welded joints from high strength alloyed steel 30HGSA is considered in the paper. The results of a comparative experimental study of controlling the properties of welded joints by changing the gas dynamics of the active shielding gas are given. The impact force of a shielding gas jet on the drop of the electrode metal is 12 times higher in conditions of two-jet gas shielding than in those of single jet shielding. It is found that gas dynamics of the active shielding gas jet determines the formation of the welded joints, their chemical properties and the properties of the welded joints from high strength alloyed steels. The consumable electrode welding method with two-jet gas shielding provides controlled dynamics in the welding area and allows controlling the transfer of the electrode metal, chemical composition of the weld, stabilizing the welding process, it ensures higher mechanical properties of the welded joints. 相似文献
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In order to reduce sulphur ( S ) and phosphorus ( P ) impurities in deposited metal, a small amount of rare earth (RE) lanthanum ( La) and yttrium (Y) were added into the coating ofE4303 electrode, a low carbon steel electrode. The microstructures of deposited metal were analyzed with metalloscope, and then the content of S and P was examined by energy dispenive X-ray spectrometer ( EDXS ), and by wavelength dispersive X-ray fluorescence (XRF) spectrometer for further examination. The results show that the proper addition of La and Y can be beneficial to the desulfurization and dephosphorization of the deposited metal. Certainly, difference in the addition amount of La and Y could lead to various desulfurization and dephosphorization efficiency, in which the former is more obvious than the latter. With the proper amount of La attd Y, there is finer microstructure in deposited metal, and mechanical properties are improved as well. The S content in deposited metal with added La and Y decreases by 44. 44 wt. % , while the P content 6. 67 wt. %, compared with that in deposited metal without La and II. 相似文献
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Microstructure and mechanical properties of laser welded joints of pure copper and 304 stainless steels 下载免费PDF全文
A continuous wave diode laser with an output power of 2.8 kW was used to join pure copper and 304 stainless steel with a thickness of 1 mm. The focused laser beam with a diameter of O. 8 mm was irradiated on the copper side of the butt joints. In process of laser welding, effects of processing primary parameters on tensile strength of the joints were investigated. The interfacial characterizations of the joints were investigated by metallographic microscope, scanning electron microscope (SEM) and energy dispersive X-ray spectroscope (EDS). The results showed that the element diffusion and solution occur and metallurgical bonding was achieved between pure copper and 304 stainless steel. The maximum tensile strength of the joints was 209 MPa when the laser power of welding was 2. 4 kW and welding speed was 12 mm/s. 相似文献
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An error back propagation (BP) neural network prediction model was established for the shunt current compensation in series resistance spot welding. The input variables for the neural network consist of the resistivity of the material, the thickness of workpiece and the spot spacing, and the shunt rate is outputted. A simplified calculation for the shunt rate was presented based on the feature of the constant-current resistance spot welding and the variation of the resistance in resistance spot welding process, and then the data generated by simplified calculation were used to train and adjust the neural network model. The neural network model proposed was used to predict the shunt rate in the spot welding of 20# mlid steel (in Chinese classification) (in 2. 0 mm thickness) and 10# mild steel (in 1.5 mm and 1.0 mm thickness). The maximum relative prediction errors are, respectively, 2. 83%, 1.77% and 3.67%. Shunt current compensation experiments were peoCormed based on the neural network prediction model proposed to check the diameter difference of nuggets. Experimental results show that maximum nugget diameter deviation is less than 4% for both 10# and 20# mlid steels with spot spacing of 30 mm and 50 mm. 相似文献