Vertical Welding Research Articles

Simplified Formula for Nominal Force at Critical Welds in the Lower Chord Node of a Novel Bracket-Crane Truss Structure

In the realm of practical engineering, engineers commonly employ rod system models for modeling and analysis, which consequently precludes them from calculating the nominal forces exerted on welds at intricate nodes. This paper addresses the design challenges of the innovative bracket-crane truss structure by proposing a simplified nominal force calculation formula for critical welds of the integrated node. This study commences with the establishment of the frame model and ABAQUS multiscale models, utilizing engineering project drawings and data, followed by a verification of the similarities between the two simulation methods. This similarity of outcomes provides a foundation for directly using the computational results from the frame model in future calculations of the forces at the weld locations. From a mechanical standpoint, this paper derives nominal force calculation formulas for horizontal and vertical welds at critical locations for three node types. Additionally, a formula for calculating nominal shear forces in vertical welds at the end plate of support nodes is introduced. The applicability of these derived formulas is subsequently validated, ensuring their efficacy in accurately capturing relevant forces at critical locations. The presented nominal force calculation formula serves as a valuable tool for optimizing the design and guaranteeing the structural integrity of the integrated node within this distinctive engineering context.

Enhancing all-position weldability and weld quality via an innovative laser-GMAW hybrid welding technique with copper liner

The change in welding position results in varied effects of gravity on the weld pool behavior. Conventional welding methods face difficulties when adjusting to welding in different positions. To address these challenges, a novel all-position welding technology, laser-GMAW hybrid welding with copper liner (CL), was introduced. CL serves a dual purpose. First, from flat to vertical welding, it supports the weld pool across various positions, thereby preventing root sagging or burn-through defects at the root of the weld in this range. Second, it facilitates accelerated weld pool solidification and inhibits its downward movement during vertical to overhead welding positions, forming the back continuous reinforcement. To quantitatively analyze the impact of CL on the temperature field during welding, finite element software was employed in this study. Moreover, the study also explored the effects of the size of the forming groove, welding current, and laser power on the weld appearance during overhead welding. As a result, with constant welding parameters, ideal welds with continuous back reinforcement were successfully achieved at five representative positions within the 0–180° range.

Eccentric compressive behavior of T-shaped welded multi-partition composite members

Six T-shaped welded multi-partition composite members were tested under eccentric compression loading by considering the influence of eccentricity and eccentric angle. The test results showed that no weld tearing occurred when the specimen was damaged, indicating that the two vertical welds could ensure the overall working performance of the specimen. The specimens exhibited the smallest bearing capacity when failing along the asymmetric axis, which was the most dangerous situation. The parametric analysis is conducted by a verified finite element model considering the influence of the slenderness ratio, section height-to-width ratio, section depth-to-width ratio, concrete and steel grade, steel ratio, and eccentric angle. If concrete contributes a larger proportion to the bearing capacity, the interaction curve of axial force and bending moment tends to protrude. Conversely, the interaction curve of axial force and bending moment gradually shrinks as the slenderness ratio increases. Based on this observation, a calculation method of T-shaped welded multi-partition composite members under eccentric compressive loading along the asymmetric axis is proposed by considering the effect of the slenderness ratio. Formulas for bearing capacity under biaxial eccentric compression are proposed based on the results of the parametric analysis.

Mechanisms of Gravitational Influence on Weld Pool Behavior and Weld Bead Performance in Variable Polarity Plasma Arc Welding across Different Welding Position.

This article comprehensively explores the cross-scale effects of gravity on macroscopic flow formation and weld bead formation in variable polarity plasma arc welding. Gravity-induced changes in welding direction were achieved through welding at different spatial positions. The properties of the weld bead were investigated at various spatial locations. Additionally, an elemental tracing technique was employed to study the internal flow behavior of molten metal. In the flat welding position, there is an observable trend of increasing grain size in the welded bead, accompanied by a significant expansion of the coarse grain zone. Consequently, the properties of the weld bead in the flat position are inferior to those achieved in the vertical welding position. This phenomenon can be attributed to the accumulation of molten metal at the exit side of the keyhole, resulting in temperature accumulation. Research indicates that the internal flow within the weld pool plays a critical role in causing this phenomenon. The study's findings reveal the presence of two distinct vortex flow patterns within the weld pool: one aligned with the welding direction and the other directed towards the interior of the weld pool. Particularly noteworthy is the substantial expansion of the flow channel area in the flat welding position, which significantly amplifies the impact of internal flow. This enhanced flow intensity inevitably leads to the increased buildup of molten metal at the keyhole exit side. These studies lay the groundwork for achieving high-quality and controllable spatial-position welding.

Monitoring for fatigue crack geometry in orthotropic steel bridge decks by application of reflected Lamb waves

Orthotropic steel bridge decks (OSDs) have been widely used as a crucial load-bearing structures in long-span bridges,. However, the weld connections in OSDs are susceptible to fatigue crack initiation due to the high stress cycle caused by vehicle loads. Reflected Lamb waves have potential in the monitoring of crack geometry, and different sensor arrangements are employed for different crack types in OSDs. Three full-scale specimens were fabricated and tested with the recommended sensor arrangements to continuously monitor two types of cracks in tests. Finite element models were also established and verified by the experimental results. Parametric studies were conducted to investigate the effects of sensor arrangements, crack lengths and angles on monitoring results. A wavelet transform algorithm was applied to analyze reflected waves and extract standardized wave features, based on which the crack geometry was evaluated. The experimental results reveal that the standardized wave features from the reflected Lamb waves change significantly with the increase of fatigue life, indicating that the features are sensitive to fatigue crack growth. The simulation results reveal that the standardized wave features effected by crack geometry are positively correlated with projected crack lengths perpendicular to the direction of wave propagation. The optimal arrangements of wave sensors for crack monitoring at deck-to-rib connections are to place excitation and reception sensors at 200 mm and 60 mm from the welds at crack initiation plates, respectively; while for cracks at rib-to-floorbeam connections, excitation and reception sensors are located at 200 mm and 50 mm distant from the horizontal welds at cut-out, respectively, and all sensors are 50 mm distant from vertical welds.

Significantly improved weldability in laser welding of additively manufactured haynes 230 superalloys by tailoring microstructure

Owing to restrictions on forming dimensions, laser powder bed fusion (LPBF) components will continue to require laser welding in the future. The post-weld thermal cracking of LPBF-Haynes 230 superalloys has become a key issue hindering their assembly in service. In this study, it was found that both the continuous TCP phase and M5Si3 silicides near the crack have a large interface strain with the matrix. Replacing the C and Si atoms with B atoms at the crack reduces the melting point of the carbides and silicides at the grain boundaries (GBs), thereby inducing solidification cracking under the residual tensile stress in the weld waist. The weldability of the alloy is influenced by the grain characteristics of the base metal (BM). Compared to parallel welds, vertical welds are inherited from the BM and exhibit smaller grains. Moreover, by reducing the heat treatment (HT) time and temperature, the grain size and grain misorientation of the BM are reduced and inherited into the weld. The GB area of the weld increases by 37% and the GB energy decreases by 7.3%, increasing the resistance to crack extension. In addition, the decreased HT temperature inhibits the carbide growth at the GBs, thereby reducing the interface strain between the matrix and carbides in the heat-affected zone and correspondingly its cracking sensitivity. This study provides theoretical guidance for improving the laser weldability of LPBF superalloys and will help accelerate the successful application of LPBF superalloy assemblies in engines.

Numerical Simulation of Welding Temperature Field, Stress Field, and Strain Field of Fillet Joint in Different Welding Sequence

For welding temperature field, stress field, and strain field in fillet joints, using the double ellipsoid heat source, the ABAQUS software platform is used to simulate and analyze the welding process of fillet joints with four different application sequences. By setting up observation points, the study analyzed the distribution of the temperature field, stress field, and strain field of the simulated welding process for these four application cases. The results show that in the vertical weld direction, the welding sequence has a large effect on the transverse residual stress; the use of isotropic welding, butt weld first and then welded fillet weld program, the maximum total deformation and angular deformation produced are the smallest.

Fault Prognosis System on Face-Mask Body Machine with Adabelief-Backpropagation Neural Network

Ultrasonic welding workload on vertical roller welding components on face-mask body machine in making masks has a highvibration of up to 20kHz. This high vibration causes the locking bolt to loosen the serrations, thus causing a greater failure of function, such as wear and tear on the teeth. If this function fails, it will cause downtime and high costs in the waiting process for the cleat component to be remanufactured. The damage prognosis system based on the condition of this machine implements a Classification of types of damage along with recommendations for maintenance activities that need to be carried out on the Face-Mask Body Machine. Classification of the type of damage to this system using There is a Belief-Backpropagation Neural Network (BPNN), a method for looking for weight settings on a neural network based on the error rate obtained in the previous iteration. This method is optimized using AdaBelief, which can adapt the step size based on the "confidence" of the previous gradient to get Convergence rates and generalization abilities better so that these types of problems can be known from the vibration signal of the machine which previously the signal was parsed using wavelet packet decomposition into frequency bands to obtain component data with low or high frequency. From the results of system performance testing, the modeling accuracy is 98.4%, so this system can be declared good and feasible to use in slack detection of vertical roller welding cleat fixing bolts.

Applying Statistical Models to Optimize the Weld Bead Geometry in the Vertical Oscillation Arc Narrow Gap All-Position GMAW

Vertical oscillation arc welding for narrow gap gas metal arc welding (NG-GMAW) has a relatively simple structure, and it is widely used in all-position pipeline field welding. However, it has some shortcomings, such as incomplete fusion defects on the sidewall and interlayer. Aiming at resolving these shortcomings, a mathematical model is proposed to obtain appropriate welding parameters in different positions. In this model, the response surface methodology (RSM) based on the central composite design (CCD) was developed to study the interactions between welding parameters and the weld bead geometry. Then the analysis of variance (ANOVA) was used to evaluate the accuracy and significance of the proposed model. Finally, experiments were carried out in flat, vertical, and overhead positions to obtain the optimal parameters. The macroscopic metallography of the transversal section of the weld bead under the optimizing welding parameters showed that the weld beads were free of defects in the sidewall and interlayers.

Application of laser welding to STS301L side structure of railway vehicles(I) - vertical incidence welding conditions for laser beam based on multiple regression analysis

Application of laser welding to STS301L side structure of railway vehicles(I) - vertical incidence welding conditions for laser beam based on multiple regression analysis

Effects of Oscillation Width on Arc Characteristics and Droplet Transfer in Vertical Oscillation Arc Narrow-Gap P-GMAW of X80 Steel

In fields, such as oil and gas pipelines and nuclear power, narrow-gap welding has often been used for the connection of thick and medium-thick plates. During the welding process, a lack of fusion was prone to occur due to groove size limitations, seriously affecting the service safety of large structures. The vertical oscillation arc pulsed gas metal arc welding (P-GMAW) method was adopted for narrow-gap welding in this study. The influence of the oscillation width on arc morphology, droplet transfer behavior and weld formation during narrow-gap welding was studied. Oscillation widths from 0 to 4 mm were used to weld narrow-gap grooves with a bottom width of 6 mm. The results show that, in non-oscillation arc welding, the arc always presented a bell cover shape, and the droplet transfer was in the form of one droplet per pulse, while the sidewall penetration of the weld was relatively small, making it prone to a lack of fusion. With an increase in the oscillation width, the arc gradually shifted to the sidewall. The droplet transfer mode was a mixed transfer of large and small droplets, and the sidewall penetration continued to increase, which was conducive to the fusion of the sidewall. However, when the oscillation width was wider than 3 mm, it led to the phenomenon of the arc climbing to the sidewall, and the weld was prone to porosity, undercutting and other welding defects. The oscillation width has a major impact on the stability of the welding process in vertical oscillation arc narrow-gap welding.

Transient Strain Monitoring of Weldments Using Distributed Fiber Optic System

The primary objective of this study was to evaluate the capability of a distributed fiber optic sensor to capture in situ dynamic transient strain formation during and post-weldment on the surface of a steel plate. The study involved a vertical manual weld of a bead on a plate on a 300 mm × 300 mm × 6.35 mm A36 steel plate (European equivalent S235J2; Chinese equivalent Q235B) clamped at the corners. A fiber optic distributed sensor was used to measure the surface total and thermal strains on the welded side of the plate adjacent to the weld path. Experimental results show a complex behavior of strain changes during the welding process and the residual strain formation post-welding. This study aims to document the use of distributed fiber optic sensing techniques in welding applications. Validations of the experimental data were performed using VrWeld, a commercial software framework for computational weld mechanics, and an iPhone FLIR One Pro. thermographic camera. The experimental results demonstrated that although distributed fiber optic sensing based on Rayleigh backscattering is an appropriate and useful technique for total strain measurements, the manufacturing and the materials used for the thermal sensors are critical in obtaining optimal results. Finally, this study highlights the challenges encountered in synchronizing large experimental data sets captured with different instruments with computational welding mechanic (CWM) models.

Behavior of double skin composite core wall subject to biaxial cyclic loads

This study performed a biaxial cyclic test on scaled double skin composite (DSC) core wall. The core wall consisted of two C-shaped DSC shear walls and steel coupling beams (SCBs) connecting the walls. In particular, seismic behavior of the core wall subject to reversed biaxial cyclic load was investigated. The failure mode of the core wall mainly included its local buckling of steel faceplate, fracture of vertical butt welds, fracture of side plate, and concrete crushing at the corners of walls. The lateral shear resistance in its two directions was mutually coupled. Once loaded in one direction, lateral shear resistance in other direction compromised. Due to energy dissipation of SCBs in their Y-direction, hysteresis loop for Y-directional loading was fuller than that for X-directional loading, and equivalent damping ratio of X-direction was 31.91% greater than that of Y-direction at ultimate point. Their initial stiffness in X-direction without SCBs configuration was the highest, and ductility coefficient of X- and Y-directions was relatively close, within 4.63–5.47%. The strain distribution curves along DSC shear wall bottoms of core wall before its peak resistance showed plane section assumption was valid under biaxial lateral load. In particular, DSC core wall high-rise buildings were promoted in this study.

A Comparison of Vertical Electro-Gas Welding and Submerged arc Welding Methods on the Corrosion Behaviors of Crude Oil Storage Tank Steel in Simulated Seawater

A Comparison of Vertical Electro-Gas Welding and Submerged arc Welding Methods on the Corrosion Behaviors of Crude Oil Storage Tank Steel in Simulated Seawater

Effect of Rotational Speed on Hardness Value and Area of Vertical Bar-Plate Rotary Friction Weld Joint

This study aims to determine the effect of rotational speed on the weld joint area and the hardness value of vertical bar-plate friction welding on dissimilar materials. Several testing methods were carried out, namely liquid penetrant, macro-observations, micro-observations and hardness test to investigation the welding results. The results of the liquid penetrant test have no effect on the welding specimens. Based on macro-observations was revealed a large enough cavity at a speed of 2.484 rpm with a cavity length of 4.76 mm, then getting smaller at a speed of 2.613 rpm with a cavity length of 2.63 mm. Then, at a speed of 4.335 rpm, no cavities were found. The micro-observation was a change in the microstructure, where in the weld metal area produces fine grains that affect the hardness value. The hardness value increases as it approaches the weld area. The highest hardness value at a speed of 4.335 rpm with a hardness value of 148.10 VHN, while the lowest hardness at a rotational speed of 2.484 rpm has a hardness value of 140.44 VHN.

Cyclic tests on steel truss-embedded steel plate-concrete composite walls

This paper performed five cyclic tests to investigate seismic performances of novel steel truss-embedded steel plate-concrete composite wall (STSCW) specimens with different prepared parameters. The studied key parameters included the cross-section size of chord member, truss-to-wall ratio, and steel–concrete interface without studs. The STSCWs experienced progressive failures of steel faceplate buckling, vertical weld fracture in the bottom corner, concrete crushing, and steel faceplate tensile fracture. Moreover, the failure modes of embedded steel truss consisted of flange necking or fracture under tension and local buckling under compression. The effects of these key parameters on seismic behaviors of STSCWs were analyzed and discussed. They showed that increasing the truss-to-wall ratio and cross-section size of the chord member improved the lateral shear resistance and deformation capacity of STSCWs. Welding studs to the flange had a negligible effect on the lateral shear resistance but reduced the deformation capacity of STSCWs. Moreover, welding studs to the flange improved the deformation compatibility between the wall and steel truss. A theoretical model was developed and validated, indicating that the predicted lateral resistances agreed well with test results.

Research on Automatic Welding Technology of Vertical Fillet Weld

In this paper, the key automatic welding technology of one-time forming the opposite fillet weld is deeply studied. With the help of the gas electric vertical welding technology and its innovation, it was successfully applied to the test and exploration of the one-time forming technology of automatic welding and equipment of the vertical fillet weld. Major breakthroughs have been made in tackling the key automatic welding technologies of one-time forming vertical fillet welds, filling the gap in this technology in the welding field and accumulating valuable experience for further research and progress of this technology.

Analysis of the Toughness of the Vertical Position GMAW Welding on Steel ST 42 with Electrode Spiral Movement Pattern

This study aims to determine the toughness value of vertical position GMAW welding on ST 42 steel with a spiral electrode motion pattern. This study consisted of ST 42 steel, cut to the standard ASTM E23 specimen as many as 20 samples. The toughness value of the GMAW welding results in a vertical position, describes the strength and toughness of the material in making ST 42 steel joints. The results of the ST 42 steel impact test with spiral; the average value of impact toughness was 135.375 Joule with an impact value of 0.2461 (J/mm²), while without treatment the average impact toughness was 183.975 Joule with an impact value of 0.3345 (J/mm²). Thus, it can be concluded that the impact toughness of ST 42 steel with a spiral electrode movement pattern is smaller than the impact toughness without welding joint treatment means that the toughness of ST 42 steel without a connection is stronger than using a welded joint with a spiral electrode motion pattern.

Effect of Residual Stress on Hydrogen Diffusion in Thick Butt-Welded High-Strength Steel Plates

Thick high-strength steel plates are increasingly being used for ship structures. Moreover, hydrogen enters the process of manufacturing and service, and large residual tensile stress occurs near the weld. Such stress can facilitate the diffusion and accumulation of hydrogen in the material, leading to hydrogen embrittlement fracture of the shell. Therefore, residual-stress-induced diffusion and accumulation of hydrogen in the stress concentration region of thick butt-welded high-strength steel plate structures need to be studied. In this study, manual metal arc welding was realized by numerical simulation of residual stress in a thick butt-welded high-strength steel plate model using the thermoelastic–plastic theory and a double ellipsoidal heat source model. To analyze residual stress, a set of numerical simulation methods was obtained through comparative analysis of the test results of relevant literature. Residual and hydrostatic stress distributions were determined based on these methods. Then, hydrogen diffusion parameters in each region of the model were obtained through experimental tests. Finally, the results of the residual stress field were used as the predefined field of hydrogen diffusion to conduct a numerical simulation analysis. The distribution of hydrogen diffusion under the influence of residual stress was obtained based on the theory of stress-induced hydrogen diffusion. The weak area of the welding joint was found to be near the weld toe, which exhibited high hydrostatic stress and hydrogen concentration. Further, the maximum hydrogen concentration value of the vertical weld path was approximately 6.1 ppm, and the maximum value of the path parallel to the weld centerline and 31 mm away from the weld centerline was approximately 6.22 ppm. Finally, the hydrostatic tensile stress in the vertical weld path was maximized (~345 MPa), degrading the material properties and causing hydrogen-related cracking. Hence, a reliable method for the analysis of hydrogen diffusion according to residual stress in thick high-strength steel plates was obtained. This work could provide a research basis for controlling and eliminating the adverse effects of hydrogen on the mechanical properties of ship structures and ensuring the safe service of marine equipment.

Improvement of inhomogeneity of microstructure and mechanical properties for 316 stainless steel laser-MIG hybrid welded joint assisted by alternating magnetic field

An alternating magnetic field was employed to improve inhomogeneity of microstructure and mechanical properties of laser-MIG hybrid welded 316 stainless steel joints. More uniform distribution of elements and ferrite phase, and austenite crystallographic characteristics in upper arc zone and lower laser zone of weld were obtained by alternating magnetic field, due to mixing of molten metal in whole weld. Longer solidification time of molten pool and more nucleation sites of austenite grain were obtained by stirring effect of magnetic field, leading to reduction of ferrite content and refinement of austenite grain. The hardness in vertical weld was more homogeneous and difference of tensile strength in both zones was reduced from 74 MPa to 10 MPa by magnetic field, due to microstructural homogeneity.