最新刊期
卷 54 ， 期 3 ， 2024
- 摘要：A rotary arc narrow gap vertical welding equipment for 9% steel large-scale LNG storage tanks is proposed, aiming to solve the welding problems in the position of the vertical seam of LNG storage tanks. The new narrow gap TIG rotary arc welding process is adopted, in which the tungsten electrode is polished into a non-axisymmetric tip, and the tungsten electrode is rotated by motor control, so that the arc heats up both sides of the narrow-gap bevel periodically, which effectively solves the problem of fusion of the side walls. In order to cooperate with this process, a new type of narrow-gap TIG rotary arc welding torch is designed with wireless rotary conductivity, automatic wire feeding and dual path gas protection. At the same time, a set of automatic welding equipment suitable for the position of the vertical seam of LNG storage tanks is proposed, including a wall-mounted trolley and a welding trolley with vacuum adsorption. A full set of test equipment, including welding trolley, fully automatic wire feeder and welding power supply, was built in the laboratory to control the welding travel of the welding torch in the vertical seam position to prevent magnetization of 9%Ni steel, and at the same time to ensure the stability of the welding process. The welding test of 24 mm thick 9%Ni steel with a single layer and a single pass and the narrow gap bevel butt joint test verified that the new process can solve the problem of sidewall fusion in the narrow gap welding of thick plates. And due to the arc cycle rotation, the molten pool has a stirring effect, so that the weld surface shaping is also very smooth and beautiful. This study provides technical and equipment support for automatic and efficient welding of LNG tank vertical seam.关键词：narrow gap;rotating arc;Side wall fusion;9%Ni steel;vertical welding;automated welding
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发布时间：2024-03-27 - 摘要：The study aims to investigate the effects of carbide orientation on the wear resistance of high-chromium alloy coatings prepared under different cooling conditions. Using high-chromium alloy flux-cored welding wires, two groups of wear-resistant coatings with different carbide orientations were prepared on Q235 substrates, namely water-cooled sample A and naturally cooled sample B. The results of sliding friction and impact abrasive wear experiments were analyzed by comparing the microstructure and microhardness, to reveal the mechanism of the effects of carbide orientation on the tribological properties of wear-resistant alloys. The results show that the front microhardness of group A with a large amount of vertically oriented (Fe, Cr)7C3 primary carbides is 16.92% higher than that of group B, which is mainly composed of eutectic mixtures and clusters of (Fe, Cr)7C3 primary carbides. In the sliding friction experiment, group A exhibits less adhesive wear distribution and a large number of microcracks, with the friction coefficient gradually decreasing to 0.007%; while group B shows a large number of metal particle adhesions, with the friction coefficient showing an upward trend, and the wear rate of 0.015% is higher than that of group A. In the impact abrasive wear experiment, the surface topography of group A is mainly characterized by shallow furrows and brittle fractures, while that of group B is mainly characterized by a large number of long and shallow furrows and spalling pits caused by micro-cutting; by comparing the weight loss curves, the wear rate of group A is 0.75%, while that of group B is 0.42%, indicating that group B with a large amount of lateral carbide distribution exhibits better impact wear resistance.关键词：overlay;M7C3;carbide Orientation;impact wear
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发布时间：2024-03-27 - 摘要：The evolution of precipitated phase of Fe-Ni based austenite alloy after aging at 740 ℃ with aging time was investigated. The effect of aging treatment on corrosion resistance of the alloy was studied by electrochemical corrosion test and Mott-Schottky analysis. The results show that aging treatment at 740 ℃ can promote the precipitation of γ′ phase [Ni3(Al, Ti)] in the alloy. The density and size of γ′ precipitated phase increase with aging time. At the same time, aging treatment can increase the number of spot defects on the alloy surface, reduce the density of the alloy passivation film, and lead to the decrease of the pitting resistance of the alloy. Constant potential anodic polarization treatment can effectively reduce the number of point defects on the alloy surface and enhance the alloy’s resistance to pitting corrosion. The self-corrosion current density of the alloy before aging is -6.697 7 A/cm2, while after aging for 4 hours and 8 hours, it is -5.716 4 A/cm2 and -6.081 2 A/cm2, respectively, both higher than before aging. After electrochemical surface modification, the self-corrosion current density of the alloy before aging is -7.490 125 A/cm2, and after aging for 4 hours and 8 hours, it is -6.127 403 A/cm2 and -6.486 164 A/cm2, respectively, still lower than before aging.关键词：Fe-Ni based austenitic alloy;aging treatment;γ′ precipitated phase;pitting resistance;surface modified technique
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发布时间：2024-03-27 - 摘要：In this article, the COMSOL Multiphysics simulation software is used to simulate the generation of arcs in a circuit when excited by a high-frequency pulsed current. Under the excitation of high-frequency pulse current, the conditions of arc generation near the surface tip of two metal plates with a certain angle and rough surface are discussed, and the formation mechanism of the arc is analyzed combined with electromagnetics. The results show that in the electric pulse-assisted rolling process, in addition to Joule heating, there is also the phenomenon of arc heating, which can generate an arc and cause two aluminum plates to combine to form a welded joint when loaded with a current of 300 A and a frequency of 10 kHz. As the current increases, the arc temperature and potential difference increase accordingly. At a current of 800 A, the arc temperature is 4 210 K and the potential difference is 54.5 V. The conditions for arc formation have been met, but the resulting arc is not stable.When loaded at 800 A, an arc of over 4 000 K can be generated and a welded joint formed within the first pulse cycle, and the heat source equation for arc generation is fitted.关键词：electric pulse assisted rolling;arc thermal analysis;ultrasonic arc;high-frequency pulse current;rough surface
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发布时间：2024-03-27 - 摘要：CX stainless steel was prepared by selective laser melting(SLM), and the microstructure and room temperature tensile properties of as-built, solution treated, and solution-aging treated samples were investigated. The results show that the microstructure of as-built CX stainless steel is composed of 99.4% martensite and 0.6% austenite. After the solution treatment, the microstructure is composed of full martensite, accompanied by the precipitation of NiAl intermetallic compounds. Further aging treatment on the basis of solution treatment significantly increased the content of austenite, The solution-aging treatment significantly improve the strength of CX stainless steel, reaching 1 426 MPa, due to the second-phase strengthening effect of the NiAl phase, while the formation of reversed austenite also improved plasticity. Fracture morphology analysis show that the fracture mechanism of CX stainless steel under the three heat treatment conditions was ductile fracture.关键词：maraging stainless steel;selective laser melting;heat treatment;microstructure;tensile property
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发布时间：2024-03-27
Important Issuse
- 摘要：To compare the adaptability of different aluminum alloy wires to the arc additive manufacturing process, four typical aluminum alloy wires (ER1070, ER2A12, ER4043, and ER5356) were selected. Using the pulse MIG arc wire additive manufacturing method, thin-walled components were fabricated under the same heat input conditions. The differences in arc additive forming, microstructure, and mechanical properties of the four wires were studied through thermal analysis, surface waviness calculation, microstructure observation, hardness, and mechanical property testing. The results showed that ER5356 wire produced the least spatter during arc deposition, and the corresponding Al5356 thin-walled component had the best forming quality and the smallest surface waviness value. The microstructure of the four aluminum alloy thin-walled components was significantly different, with Al1070 having the coarsest structure and the most porosity defects; Al2A12 having fine equiaxed grains; Al4043 having developed Al-Si eutectic structure; and Al5356 having the densest matrix. Mechanical property testing showed that the tensile strength of the four aluminum alloy thin-walled components was higher in the X direction than in the Z direction, and the elongation difference between the X and Z directions of Al1070 and Al4043 was greater than that of Al2A12 and Al5356. Al1070 had the lowest average hardness and tensile strength, but the highest elongation; Al2A12 had the highest average hardness and tensile strength, but the elongation was less than 10%, and the microcracks in the structure limited the further improvement of its mechanical properties; Al5356 had slightly lower average tensile strength than Al2A12, with an average elongation of over 20%, showing good comprehensive mechanical properties. In summary, ER5356 wire is more suitable for arc additive manufacturing of aluminum alloy components, and Al5356 components have the best comprehensive performance.关键词：wire and arc additive manufacturing;aluminum alloy;forming quality;microstructure;mechanical property
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发布时间：2024-03-27 - 摘要：The wear-resistant surfacing layer was prepared by arc cladding Fe-Mo-V-C flux cored wire on Q235 steel substrate.The microstructure of the deposited metal was studied by optical microscope (OM) and scanning electron microscope. The phase of the deposited metal was calibrated by X-ray diffraction (XRD). The wear resistance of the deposited metal was analyzed by pin on disk wear test.The results show that when the content of C element increases, a large number of fine VC hard phases and mesh-like Mo-Fe-C compounds are formed in the deposited metal, which improves the wear resistance of the deposited metal; The VC hard phase formed first in the deposited metal plays the role of heterogeneous nucleation, grain refinement and pinning dislocation; Mo element exists in the deposited metal in the form of Mo-Fe-C white dendrite, which plays a role in refining the grain and enhancing the wear resistance of the matrix.关键词：arc deposition;molybdenum vanadium alloy;carbon content;VC hard phases
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发布时间：2024-03-27
Welding Material
- 摘要：The cyclone separator is a key component of circulating fluidized bed boiler. At present, the fillet weld of cyclone separator tube panel is welded by mechanical gantry welding or manual welding, which has problems such as poor weld quality, excessive welding spatter and poor welder working environment. This paper introduces a kind of robot welding equipment for cyclone separator tube panel, which can realize the intelligent control of the whole process of automatic positioning, automatic arc starting, automatic adjustment of welding gun posture and automatic welding of tube panel fillet weld. The hardware system, software system and auxiliary devices of the equipment are introduced, and the process flow of tube screen welding is designed. Welding process tests and applications were carried out using this equipment, and the results indicate stable operation, accurate laser positioning, good weld formation, minimal welding splatter, effective smoke and dust treatment, fillet sizes meeting standard requirements, and a welding speed of up to 800 mm/min or more. The comprehensive efficiency of welding has increased by over 40%. The intelligent welding equipment for cyclone separator tube screens has realized the automation of fillet welding, enhancing welding quality and efficiency, reducing labor intensity, and improving the working environment.关键词：cyclone separator;Robot welding;tube screen fillet weld;intelligent control
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发布时间：2024-03-27
Welding Equipment
- 摘要：Asymmetrically filled double-sided welding of 50 mm ZG/NM dissimilar steel composite used in the middle trough was carried out by oscillating arc narrow-gap GMAW. With the help of swing arc, the weld is well formed and the incomplete defect of side wall is well controlled. The microstructure and properties of joints at different positions along the plate thickness direction were studied. The results show that there are some differences in the microstructure of different layers due to different welding specifications. The tensile properties of the different filling layers are good and comparable to those of the filling metal. The bottom layer at the side of the deep U groove has the highest strength, and the strength of the single V-shaped layer is between the top and the bottom of the U-shaped filler metal. The hardness of the filler metal changes with the location, from the single U-side to the V-side, the hardness value decreases gradually. The hardness value of base metal is the highest and the hardness value of filling metal is the lowest in different filling layers.关键词：middle trough;dissimilar steel;narrow clearance groove;swing arc;heat input;ferrite
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发布时间：2024-03-27 - 摘要：Welding with flux sheet confined arc ultra-narrow gap welding A new ultra-narrow gap welding method using flux sheet to constrain arc with 4~6 mm I groove. The matching between welding process parameters will affect weld formation. We independently designed and produced a set of ultra-narrow gap welding device for confined arc with flux sheet, which improved the stability and automation of welding process. The weld shape at the arc quenching position and the melting morphology at the end of flux sheet were preserved by the method of instantaneous arc interruption. It was found that both welding voltage and flux belt feeding speed affected weld formation by changing the length of flux sheet on arc, and the length of flux sheet on arc can be expressed as the confined area of flux sheet on arc wall. The results show that when the confinement area of flux sheet on arc wall is moderate, the arc centralized heating area will move down to the bottom of the gap and the root of the side wall, and a good fusion of the root is obtained. When the confined area of flux sheet on arc wall is large, the constrained degree of arc is too strong, the arc heating area is concentrated at the bottom of the gap, the arc heat distributed at the root of the side wall is little, and there will be molten pool accumulation on the weld path. When the constraint area of the flux sheet on the arc wall is small, the constraint degree of the arc climbing along the side wall is weak, resulting in the heating area concentrated on both sides of the wall, and it is difficult to form an effective molten pool at the root of the groove, and finally form a hole weld. Finally, a series of process parameter matching tests were carried out to obtain the optimal process parameter matching range of the ultra-narrow gap welding confined by the flux sheet, and the optimal process parameters were used to carry out the ultra-narrow gap single-pass multi-layer welding tests.关键词：narrow gap welding;welding voltage;feeding speed;confined area of wall;weld forming
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发布时间：2024-03-27 - 摘要：10 mm thick N06022 nickel base alloy was welded by TIG + SMAW. The microstructure, microhardness, corrosion properties and tensile properties of the joint were analyzed and studied. The results show that the surface of the joint welded with TIG+SMAW is well formed, the whole weld is silver white, and the semi-elliptical fish scale is evenly distributed. There is an obvious dividing line between the base material and the weld zone structure, and there is no obvious heat-affected zone. The weld zone structure is equiaxed and dendrite. The hardness of the whole welded joint is distributed in an "M" shape, and the microhardness in the NZ region is more stable. Near 250 HV, the HAZ region is higher than the BM region, while the NZ region is lower. The microhardness of the joint from the HAZ region to the NZ region has little change. The average tensile strength of welded joint (799 MPa) is higher than that of base material (782 MPa), and the average tensile strength of welded joint is 2.56% higher than that of base material, which ensures the reliable operation of this kind of welded structure. The corrosion performance of the joint meets the technical requirements and standards of the equipment.关键词：N06022 nickel base alloy;TIG+SMAW welding;microstructure;mechanical property
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发布时间：2024-03-27 -
Welding Process Experiment of U-Rib Welds on Verrazano-Narrows Bridge in New York with Welding Robot
摘要：Orthotropic steel bridge deck is widely used in large-span modern steel bridges due to its lightweight and high bearing capacity, with the U-shaped rib welding technology being a key factor in the production of bridge panels. Taking the U-rib welding test on the Verrazano-Narrows Bridge in New York as an example, this paper introduces the welding process for U-rib and deck groove fillet welds. Unlike the traditional method requiring 4 weld passes, this study achieved a single pass for both sides of the U-rib groove fillet welds by adjusting the U-rib weld groove angle (54° for triangular shape and increased weld formation factor), root face size (2.5~3.0 mm), welding parameters, and using a welding robot with arc tracking system for welding. This process overcomes the technical issues of insufficient penetration, burn-through, cracks, and edge bite, and the welding efficiency is four times higher than the traditional method. The penetration depth reaches 80% of the U-rib thickness, with no weld leakage and good appearance quality. All samples passed the random sampling inspection by the owner, filling the technical gap in the field of U-rib welding at home and abroad. The focus of this study is the efficient and high-quality U-rib welding, with the innovation lying in the proposed single pass symmetric horizontal position welding process. The successful application of this process provides an important reference for steel bridge manufacturing at home and abroad.关键词：orthotropic steel bridge deck;U-shaped rib;groove weld;single pass symmetric welding;welding process optimization;Robot welding- 7
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发布时间：2024-03-27 - 摘要：The study aims to explore the impact of laser brazing process parameters on the quality of bump solder joints in high-density chip manufacturing. A three-dimensional transient thermal coupling numerical model was established using finite element methods, and the Gaussian volume heat source model and iSoldering software were utilized to simulate the temperature and stress fields of SnAgCu brazed convex points. The research investigated the variation rules of SnAgCu brazing solder joints under different powers of 10 W, 15 W, 20 W, and different spot radii of 0.09 mm, 0.3 mm, and 0.5 mm. The findings revealed that laser power and spot radius are the key parameters affecting solder joint quality. With some parameters remaining unchanged, an increase in laser power resulted in more complete brazing material melting, better wettability, but also greater equivalent stress. The increase in spot radius led to a decrease in solder joint temperature and equivalent stress. By comparing numerical simulations with actual brazed joints, the results showed that the best quality of SnAgCu convex point laser brazing solder joints was achieved when the laser power was 15 W, the spot radius was 0.09 mm, and the welding speed was 0.1 mm/s. The simulated convex point brazing solder joints matched the actual brazed results with an accuracy of 85%, verifying the accuracy and reliability of the simulation results. This study provides theoretical guidance for improving actual laser brazing processes and explores the impact of the thickness of intermetallic compounds formed between the brazing material and the solder pad on solder joint quality, offering a theoretical basis for enhancing solder joint connection strength.关键词：laser soldering;salient point;finite-element modeling;temperature field;stress field
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发布时间：2024-03-27 - 摘要：Orthogonal test on 5 mm thick A105 forged steel pipe fittings laser self-melting welding process parameters optimization, to determine the degree of influence of each process parameter on the response of the amount and the optimal welding process, the optimal process parameters under the organization of the welded joints and mechanical properties of the study. The results show that: under the conditions of laser power 2.0 kW, welding speed 7 mm/s, defocus -1 mm, shielding gas flow 20 L/min welding parameters, the welding effect is the best, and the high-speed and stable laser butt fusion welding of 5 mm thick A105 forged steel can be realized, and the welded joints are well shaped; the laser power has the greatest influence on the response quantities, and the depth of fusion and tensile strength increase with the increase of laser power; the weld zone (WZZ) and the weld area (WZZ) are the most affected by laser power, and the weld joint organization and mechanical properties are investigated. increase; the weld zone (WZ) grain size is smaller, the weld metal is mainly composed of lath martensite, and its hardness is higher than that of the base material (BM); the heat-affected zone (HAZ) is narrower, and there is a phenomenon of coarse and fine grain delamination; the hardness of the welded joints is not uniformly distributed, and there is a maximum hardness of 408.8 HV in the fusion zone (FZ) of the weld joints; and the strength of the weld joints is better than that of the base material.关键词：laser self-fusion welding;A105;orthogonal test;welding process optimization;microstructure;microhardness;mechanical properties
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发布时间：2024-03-27 - 摘要：The CR400BF EMU’s body end wall is assembled from closed cavity aluminum alloy extrusions with a significant amount of welding, which results in substantial welding distortion, making size control difficult and affecting vehicle assembly precision and appearance quality. This study investigates methods to control welding distortion in the CR400BF EMU body end walls. By combining welding simulation and actual production, an optimized set of welding distortion control methods for the end walls is proposed from three aspects: structural optimization, pre-welding counter-distortion, and welding process optimization.In terms of structural optimization, an enclosed type extrusion structure with posts is used instead of the traditional open type extrusion structure, which increases the stiffness of the end wall. For pre-welding counter-distortion, effective control of welding distortion is achieved by adjusting the contour curvature of the side bending beams and the assembly width of the external bending beams. Regarding welding process optimization, an alternating “longer then shorter, larger then smaller” front and back welding sequence is employed, and the spacing and number of segmented welds are adjusted to further reduce welding distortion. This ensures the critical dimensions of the end wall, thereby improving product quality and production efficiency.关键词：CR400BF;end wall;welding distortion;simulation;structural optimization;pre-welding counter-distortion;welding process optimization
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发布时间：2024-03-27 - 摘要：The quality of the safety end in nuclear power main equipment directly affects the safety of the entire system. And defects were generally repaired locally by manual welding, which was difficult to meet the requirements of the third-generation nuclear power technology. In the process of repairing the safe end in the nuclear power equipmen(HPR1000), the entire safe end was removed for the first time and successfully repaired through all-position boss cladding and narrow gap welding technology. Moreover, the buttering layer of different welding thermal cycle states in the remanufacturing process was studied, and the physical and chemical properties of the corresponding repair simulation parts were tested. The results showed that the mechanical properties of the repaired simulated parts were tested for tensile, impact, bending, and which fully met the requirements. Meanwhile, no related defects were found in non-destructive testing (PT and UT) of the welded simulated parts. Finally, the microstructure and grain size were tested and analyzed, the microstructure of weld was coincident and meliorative. The successful repair of the safety end further promotes the development of remanufacturing technology nuclear power equipment.关键词：HPR1000;nuclear power safety end remanufacturing;buttering layer;overall repair;mechanical properties
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发布时间：2024-03-27 - 摘要：Aiming at the defects such as indentation, deformation and distortion caused by improper control of electrode pressure in spot welding of high-strength biphase steel of door wing plate, the influence of electrode pressure on spot welding quality was analyzed. ANSYS numerical simulation software is used to compare and analyze the equivalent pressure changes of the plate under different electrode pressures. The analysis results show that compared with the electrode pressure of 4000N, the equivalent pressure of the solder joint fluctuates less and the plastic deformation is relatively small when the electrode pressure is 3000N. For the spot welding of the door wing plate, the reasonable spot welding electrode pressure is determined to be 3300N, and the phased control curve is designed. The FANUC spot welding control system is used to monitor and compensate the electrode pressure in real time, and the fluctuation of the electrode pressure is effectively controlled. In addition, the pressure of the electrode can be adjusted in real time according to factors such as plate shape change and electrode wear with the use of the pressure equalization macro.The experimental results show that the electrode pressure fluctuation is controlled within ±5%, the indentation depth on the surface of the solder joint is reduced by about 20%, and the quality of the solder joint is obviously improved after using the equal-pressure balance control.关键词：robot resistance spot welding;servo gun;electrode pressure;numerical simulation;equalizing balance
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发布时间：2024-03-27 - 摘要：This paper systematically discusses the forming process of S32750 super duplex stainless steel pressure vessel heads. Through the analysis of the chemical composition, microstructure, mechanical properties, and corrosion resistance of S32750 super duplex stainless steel, it is determined that the material has high strength, good weldability, and corrosion resistance. Based on the material properties and relevant standards, a two-step forming process is formulated, including cold stamping pre-forming and hot stamping final forming. Key control points of the forming process include raw material inspection, marking and blanking, edge preparation, cold and hot stamping forming, and heat treatment for recovery of material properties. After forming, the shape and size, thickness, hardness, and ferrite content of the head are inspected to verify the effectiveness of the forming process. Tensile, impact, and intergranular corrosion tests on the head blank material show that the mechanical properties and corrosion resistance of the head have been well restored. The effectiveness of the S32750 super duplex stainless steel head forming process is summarized, providing experience for the manufacture of duplex stainless steel pressure vessels.关键词：S32750 super duplex stainless steel;pressure vessel head;hot forming;solution treatment for recovery;mechanical properties;corrosion resistance
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发布时间：2024-03-27 - 摘要：The resistance spot welding of DH980-GI steel sheet of body-in-white was taken as the research object. By means of optimization design of welding parameters and analysis of joint strength, hardness and liquid metal embrittlement (LME), the influence of welding current and other parameters on the performance of resistance spot welding joint of steel sheet was studied. In the meantime, the brittleness sensitivity of spot welding liquid metal of the was also analyzed. The experimental results show that under the conditions of 4.5 kN electrode pressure and 380 ms welding time, the microhardness values of the fusion zone of the joints with different currents are similar, all within the range of 470~510 HV, and the fusion zone diameters meet the standard requirements. The LME test results show that no LME cracks were observed in the current range of 6.8~10.5 kA, while A-type LME cracks appeared in the current range of 11~14.5 kA. The mechanical properties test results show that when the welding current is 6.8 kA, the shear strength of the joint is 901~911 MPa, and when the welding current is 8.1 kA, it is 738~783 MPa. The shear force is above 21 kN, which meets the standard requirements.关键词：body-in-white;DH980;resistance spot welding;welding parameter;liquid metal embrittleness
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发布时间：2024-03-27 - 摘要：In this paper, 0.5 mm TA1 industrial pure titanium was selected as the research object, and the welding tests were carried out at different laser powers and different welding speeds. After welding, the effects of different welding speeds on the macrostructure, microstructure, mechanical properties, hardness and corrosion resistance of TA1 weld were analyzed. The results show that with the increase of welding speed, the width of weld decreases gradually and the forming quality of weld surface improves. In the weld structure, the coarse α phase decreases gradually, the needle α phase increases gradually, and the grain is refined. The tensile strength of the joint gradually increases and tends to the strength of the base metal, and the corrosion resistance is getting better and better. With the increase of welding power, the weld width gradually increases, the coarse α phase in the weld structure gradually increases, the tensile strength gradually decreases, and the corrosion resistance becomes worse.关键词：industrial pure titanium;laser welding;welding parameter;microstructure
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发布时间：2024-03-27 - 摘要：The aim of this study is to explore the influencing factors of deflection changes during the welding process of aluminum alloy A-type urban rail vehicle bodies with integral side wall structures, as well as the variation rules of deflection. Using 5 sets of test vehicles, adjust the distribution position of welding fixture support in the body assembly group, prefabricate the deflection of single components on the side wall, and prefabricate the deflection value of the body assembly, and observe the changes in the deflection of the body after welding. The results show that when the support is distributed at the center of the doorway, the deflection rebound after welding reaches 13 mm; When the support is distributed on both sides of the doorway, the rebound amount decreases to 11mm. After prefabricating the single component of the side wall with a deflection of 15mm, the deflection rebound after welding further decreased to 4.5mm. In addition, when the total prefabricated deflection values are 19 mm and 16.5 mm respectively, the post weld deflection values are 15.3mm and 13mm, and the rebound amount remains within the range of 3.5-4.5 mm.Research has shown that the distribution position of welding fixture support in the overall composition of the vehicle body and the deflection prefabrication of single components on the side wall are key factors affecting the post welding deflection of the vehicle body. By prefabricating the deflection of single components on the side wall, the amount of deflection rebound after welding can be effectively reduced. In addition, while ensuring the theoretical deflection requirements of the design, using smaller deflection prefabrication is more advantageous for the size of the vehicle body.关键词：deflection prefabrication;tooling support;deflection rebound;side wall;vehicle body assembly
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发布时间：2024-03-27 - 摘要：Welding between ASME SA312 TP347H austenitic stainless steel pipes and ASTM SA335 P5 ferritic heat-resistant steel pipes presents challenges such as metal dilution, carbon migration, and residual stress. Considering the impact of dilution, two welding materials, ER309 and ERNiCr-3, were selected to create six welding procedure specifications based on whether post-weld heat treatment (PWHT) was applied and whether a cladding layer was welded. These specifications were tested through welding experiments, mechanical property tests, and metallographic examination to analyze the performance of welded joints under different procedures. The results show that the appearance inspection and RT results meet the relevant standards. The tensile strength of all specimens exceeds the standard requirement of 415 MPa, with a maximum reaching 505 MPa, and the elongation after fracture is above 25%, fulfilling the standard requirements. Impact test results also meet the standard requirements, with the average impact absorbed energy of the TP347H side heat-affected zone ranging from 54.0 to 70.5 J. The hardness near the P5 side base metal heat-affected zone of the welded joint without PWHT exceeds the standard in the direct welding method, while the hardness values of welded joints with PWHT meet the standard requirements. Carbon diffusion is more pronounced in welded joints with PWHT, while the least carbon diffusion occurs in welded joints that use ERNiCr-3 welding wire for cladding and undergo post-weld heat treatment. Based on the comprehensive results, the welding joint performance is optimal with the ERNiCr-3 cladding layer and post-weld heat treatment process, meeting the standard requirements without the need for PWHT, making it more suitable for on-site welding.关键词：TP347H;P5;dissimilar steel welding;post-weld heat treatment;post-heating treatment;overlay cladding layer
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发布时间：2024-03-27 - 摘要：Aiming at the wear and failure requirements of a certain type of gas turbine power turbine rotor blade, a crack-free K438 joint was prepared by TIG welding, and the microstructure and mechanical properties of the K438 joint were analyzed. The results show that the joints are beautifully formed and have no defects such as cracks. The γ-based solid solution in the surfacing area is dispersed with Cr-rich M23C6 and M6C white phases such as columnar, granular and dendritic phases. Furthermore, the bonding line hardness is as high as 452 HV0.5, the hardness of the surfacing area is about 278 HV0.5. In addition, the average tensile strength of the joint is 403.3 MPa, and it is fractured in the surfacing area in the mode of brittle and ductile fracture.关键词：K438 alloy;nickel based welding wire;TIG;microstructure
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发布时间：2024-03-27
Welding Technology
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