Plate Welding Research Articles

High-cycle rotating-bending fatigue performance of S690QL welded joints

In recent decades, high-strength steels have become increasingly popular in the construction industry. Materials like S690QL steel are mainly characterised by their enhanced mechanical properties, including high yield and tensile strength. As a result, this leads to improved performance, durability, and safety of steel components, making such materials commonly used in several offshore applications due to their exceptional strength and cost-efficiency. Within the offshore industry, the most critical connections are usually the welded joints, thus rising significant concerns regarding the characterisation of the material in the area close and affected by the welding process. Furthermore, this material is highly prone to the appearance of cold cracks. To address these issues, rotating-bending fatigue tests were successfully conducted on S690QL steel to evaluate and compare the fatigue life within different regions of the investigated welded joints, specifically the weld material, heat-affected zone and base material. Increasing thickness of the weld plates was found to have a negative impact on the fatigue resistance, which aligns with the lower static strength for the thicker case. Also, variations in fatigue strength across the thickness were observed. The heat-affected zone exhibited a heterogeneous microstructure, leading to increased fatigue variability during testing, but the fatigue resistance observed aligns with the findings in the literature for comparable steel grades. Detailed experimental results are presented, particularly regarding this heat-affected zone, where the majority of fatigue failures occur, which provide bases for the development of new normative material-scale SN curves.

Analysis of Electric Current on Aluminum Plate Welding Using MMA (Manual Metal Arc) Method

Many industries depend on welding, which joins materials with heat. This research focuses on Manual Metal Arc (MMA) welding aluminum plates due to its adaptability for thin materials and compatibility with aluminum's unique properties. The study investigates how electric current affects aluminum plate MMA welding, improving welding methods. The study examined the effect of electric current on aluminum plates using the MMA method using a qualitative descriptive research design. Sorong Merchant Marine Polytechnic's workshop laboratory conducted the research from February to May 2023 using AWS E 6013 welding electrodes and ASTM A36 plates. Data was collected through observation, documentation, and literature review, then analyzed using data reduction principles. Results show that electric current variation significantly affects welding characteristics. Increased amperage penetrates deeper, but excessive current can melt and weaken joints. Amperage, weld rate, joint quality, and penetration depth must be balanced. The study emphasizes precise welding control, improving welding efficacy. The complex relationship between critical parameters emphasizes the need for careful equilibrium and the importance of following welding guidelines and parameters in the Welding Procedure Specification. As inadequate or excessive current can affect weld quality, this research improves MMA aluminum plate welding results.

Experimental and theoretical study on seismic behavior of a new UHPFRC sandwich wall and wall-wall joint

A new type of precast ultra-high performance concrete (UHPFRC) sandwich wall is proposed in this study. The proposed UHPFRC sandwich wall is composed of the UHPFRC layers, extruded polystyrene foam (XPS) board layer, and short UHPFRC columns connecting the UHPFRC layers. Compared with the traditional reinforced concrete wall, the UHPFRC sandwich wall possesses lower self-weight, less reinforcement, and higher strength. In addition, two types of wall-wall vertical joint connection methods, flexible cable connection and embedded steel plate welding connection, are proposed. The pseudo-static tests on five UHPFRC sandwich wall specimens were conducted to study the effects of UHPFRC layer thickness, reinforcement ratio, and width of edge solid area on the seismic behavior of the wall. Then, the seismic performance of different connection methods was studied by pseudo-static tests on two T-shaped UHPFRC sandwich wall-wall joint specimens. Test results demonstrate that the unreinforced UHPFRC sandwich wall, with 20–30 mm UHPFRC thickness and 150 mm edge solid area, showed excellent cracking resistance and seismic behavior. The cracking loads are more than 50% of the peak loads, and the bottom shear capacity to self-weight ratios are generally more than 35. The seismic behavior of the wall-wall joints connected by the flexible cable and embedded steel plate welding are both reliable. Finally, formulas for cracking and peak load of the UHPFRC sandwich wall are proposed and the fiber model is developed for analysis of the wall-wall joint, which is verified by the test results to be accurate and reasonable.

Fatigue behavior of SMA490BW welded components considering AHT with traction structural stress

Quantitative characterization on fatigue properties of SMA490BW welded components with annealing heat treatment is very significant for steel structure service. In this work, the relief of residual stress during welding and the subsequent annealing heat treatment process of plate and tube-to-plate components is simulated using the finite element method with the Norton-Bailey creep model. Traction structural stress is used to evaluate the fatigue life of SMA490BW plates and tube-to-plate components under two annealing heat treatment processes by considering residual stress. It is found that the residual stress distribution state of welded components keeps the same tendency by annealing heat treatment, while the peak value of longitudinal and transverse residual stress is decreased significantly due to the increase of equivalent creep strain with the width of the welded plate exceeding 6 times the thickness. The fatigue data for two annealing heat treatment processes and welding of plate and tube-to-plate components are within a 95% confidence interval of the ASME Master SN curve. The influence of load range on fatigue life is more significant than that of welding residual stress. By quantifying the residual stress in the load ratio correction, the standard deviation of fatigue data for different full-scale components more convergent.

Ultrasonic spot welding of open-cell Cu foam and Al plate: A study on the quality of joints

As a type of novel material, open-cell copper (Cu) foam has been widely applied in electrode production of batteries, due to its functional and structural properties. The use of ultrasonic welding technique to join Cu foam and aluminium (Al) plate has been proven to be feasible, but quality evaluation of the joints remains a blank to be filled in. In this study, orthogonal test design is used to investigate the effects of welding pressure, welding amplitude, welding energy and the interaction among the three parameters on the shear-tensile strength of ultrasonically welded joints of Cu foam/Al plate, and it is influenced by the three parameters in the following order: welding pressure > welding energy > welding amplitude. Based on the results of the orthogonal test, a Cu foam/Al plate ultrasonic welding joint evaluation system is established, based on which, qualitative and quantitative analysis on the quality of the joints classified the joints into three grades. The optimal parameter combination of the welding joint of Cu foam/Al plate is obtained as follows: 0.5 MPa, 65 %, 130 J, under which the porous structure of the joint is complete while its tensile strength is equal to or even better than the base material.

Research on intelligent perception and decision system for special welding mechanical arm of float plate in crude oil storage tank

Abstract In the rapid development of the petrochemical industry in the context of the increasing number of large tanks, large tanks in the production and installation process encountered the first problem the pontoon plate welding deformation and weld seam is too large and other defects, through the construction of the ship plate welding special robotic arm of the intelligent perception and decision-making system to solve such defects. Summarize the Structure of crude oil storage tanks and welding process characteristics based on the ultrasonic distance measurement in the distance sensor to obtain the characteristic data set, combined with the distinct data and computer programming language to build the intelligent perception and decision-making system of the unique robotic arm for ship plate welding. They set the relevant parameter values based on simulation experiments on the welding of a particular robot arm perception and decision-making system for the application of example analysis. Compared to the traditional LSTM algorithm, the YOLO-v5 network-driven weld target detection algorithm has a 5.5% higher accuracy and a 9.1% higher success rate in time robustness evaluation. In addition, the welding decision model based on the DDPG algorithm possesses excellent computational accuracy, and the average error of each parameter in the welding decision of the ship plate is controlled within 5%. This study greatly improves the welding quality of the pontoon plate of crude oil storage tanks and provides solid technical support for the successful completion of the project.

Thermal modeling of friction stir welding of thick high-density polyethylene plates

The process temperatures in the friction stir welding of thick polymer plates play a significant role in the joint's quality since the process is characterized by mixed solid and viscous flow states. The heat generation mechanism in each state is fundamentally different, with heat being generated by friction in the solid-state and by viscous shear flow in the viscous state. In this study, the heat generation and dissipation in the friction stir welding of 14 mm thick high-density polyethylene plates were studied numerically through solving the direct heat conduction problem. Two models of heat generation were used in the numerical solution and the effect of the pin rotational speed on the process temperatures was investigated. It was shown that the utilization of a mixed heat generation model consisting of both the solid state and the viscous shear flow considerably improves the numerical model predictions. The temperature predictions were validated through welding experiments and showed a temperature difference of 3 %. Furthermore, it was found that the welding process stabilizes at rotational speeds higher than 800 rpm, where no considerable change occurs in the volume of the viscous flow region and the welding power requirement. The numerical results based on the combined solid-viscous heat model were in good agreement with the experimental thermal histories.

Welding of 20 mm thick EH40 steel by means of a single-pass hybrid laser-arc welding technique

In the naval applications, as well as for infrastructure and construction sectors, welding of thick steel plates (>15 mm) has become of crucial importance. Nowadays, the common techniques involve several passes of traditional Gas Metal Arc Welding (GMAW) to fill a gap with a precise geometry. These techniques are, inevitably, time consuming due to the necessity of multiple passes, material consuming because of the volume of the gap which needs to be filled, and complicated due to the precise preparation of the joints. To overcome these drawbacks, we propose here a Hybrid Laser-Arc Welding (HLAW) technique in a configuration which allowed us to achieve a sound weld of two plates, 20 mm thick, of naval steel EH40 in a single pass. The goal has been obtained with a 15 kW fiber laser and a welding speed of 1500 mm/min. The most important result of this research is that the welds have been performed in a simple butt configuration, with straight edges of the plates and without any chamfer or additional preparation. Moreover, the length of the weld seam, 1 meter, guarantees the stability and the solidity of the process, its scalability over longer plates, and thus, an easy implementation on an industrial machine for massive production.

Single pass laser vacuum welding of thick steel plates using electromagnetic support

The increasing demand for renewable energy produced by offshore wind turbines goes along with an increased demand in the production of offshore wind turbine foundations, so called “monopiles”, which are made by joining thick metal sheets. The industrial standard of multi-layer submerged arc welding (SAW) for joining of thick metal sheets is the current bottleneck in the production of monopiles. A possible increase in productivity by the implementation of high-power laser welding in a newly developed mobile vacuum chamber (MoVac) and an electromagnetic root support is the subject of this study. Single run butt welds are performed in flat position on S355 mild steel of thicknesses up to 80 mm using a disc laser system with 1030 nm wavelength and a maximum output of 60 kW. The laser optic is fixed on the MoVac-System which is held and manipulated by an articulated robot.

Application of synchronized tandem welding to high-hardness armor steel

Several studies have been conducted to improve combat vehicle capabilities, such as the bulletproof performance of armor and fuel efficiency through weight reduction. Titanium alloys and ceramic materials are expensive and difficult to process; therefore, they can be applied only in specific locations. In addition, arc welding, which is relatively inexpensive compared with other welding processes, is widely used in industrial fields; however, because welding is often performed in multiple passes to join one part, the productivity is reduced. Therefore, in this study, mechanical properties were investigated according to production time and heat input by applying tandem pulse gas metal arc welding (GMAW) to increase productivity. The experimental data were obtained by varying the wire feeding speed. In addition, the current–voltage waveforms were measured, and the volume shift was analyzed by comparison with images captured using a high-speed camera. To analyze the mechanical properties of the tandem weld for the welding of high-hardness armor plates, the appearance (top bead and back bead), cross-section, hardness, tensile test, impact test, and spatter generation of the welded part were analyzed. The results show that all Tank-automotive and Armaments Command (TACOM) standards for the base material were met when the tandem wire feeding speed was 11 + 11 m/min, and the single-pass process increased production speed by a factor of more than 10. Tandem pulse GMAW is shown to be a viable option for improving productivity and maintaining high-quality welds for high-hardness materials.

Research on Tensile Test of Dissimilar Steel Body Solder Joints

With 22 mnb5 St16 and ordinary steel as the research object, under the conditions of medium frequency spot welding connection plate welding, solder joint for the electric logging under shear load test, determination of solder joints, solder joint and away from the solder joint around the base of strain, according to measurement data analysis of solder joints and the deformation regularity of parent metal. The test results show that the strain in the spot welding joint distribution is uneven, the center of the welding strain is small, large deformation mainly exist in the heat affected zone, near the solder heat affected zone is the main area prone to give in. Away from the solder joint area of the parent metal, the influence of solder joint is small, mainly tensile strain, and strain as the load increases, solder joint strain is negative, the center is linear, and basic antisymmetric location of strain values different test points.

Advanced Strengthening of Steel Structures: Investigating GFRP Reinforcement for Floor Beams with Trapezoidal Web Openings

Enhancing existing steel structures becomes imperative upon alterations in usage or geometric configurations, such as introducing web openings in floor beams to accommodate various services. The utilization of welded steel plate and conventional strengthening methods often presents challenges, which may be mitigated through the adoption of composite materials like Fiber Reinforced Polymers (FRP). However, research on the application of FRP to steel beams with web openings remains limited, predominantly focusing on beams with rectangular openings of modest dimensions. This study delves into the application of Glass Fiber Reinforced Polymers (GFRP) to strengthen reinforced steel floor beams featuring trapezoidal openings. Leveraging a rigorously validated numerical model derived from previously published findings by a contributing researcher, the investigation showcases that the proposed GFRP reinforcement scheme exhibits performance comparable to conventional steel plate welding techniques, while preserving the inherent strength of the original solid beams.

Study on the Comparison of Electron Beam Welding and Hybrid Laser-Arc Welding of Thick High-Manganese Steel Plate for Cryogenic Applications

Environmental protection policies have led to a focus on clean energy from Liquefied Natural Gas (LNG) and thus, its demand is increasing. Several studies for the development of cryogenic materials and fabrication technologies for storage and delivery of LNG are presented worldwide. Recently, International Maritime Organization (IMO) acknowledged that high-manganese steel was one such cryogenic material for application in LNG storage. Thus, high-manganese steel is expected to be increasingly used in the cryogenic storage industry because of its excellent material properties such as low-temperature toughness and tensile strength. A variety of researches on the welding technologies are available, including arc welding, laser welding and hybrid laser-arc welding. However, electron beam welding (EBW) has not been widely studied. In this work, EBW was investigated for the thick high-manganese steel plate and its mechanical properties were evaluated and compared with the characteristics of hybrid laser-arc welding. Our study indicates that EBW exhibits better mechanical properties than the hybrid laser-arc welding and it can be an effective potential candidate technology for welding of thick high-manganese steel plate with application in cryogenic storage tank.

A Study on Bead on Plate (BOP) Test for Laser Welding Application of Stainless Steel to Liquified Hydrogen Tank (PART I: STS 304)

Liquified hydrogen is considered a new energy resource to replace conventional fossil fuels due to environmental regulations by the IMO. When building tank for the storage and transportation of liquified hydrogen, materials need to withstand temperatures of -253°C, which is even lower than that of LNG (-163°C). These materials mainly include austenitic stainless steel and high-manganese steel, especially STS 304 steel mainly used to build liquified hydrogen tank. When building the tanks, both the base material and welding zone need to have excellent strength in cryogenic condition, however, manual arc welding has several issues due to prolonged exposure of the base material to high temperatures. Laser welding, which has some benefits like short period of exposure time and decrease of thermal affected zone, is used many industries. In this study, to determine the laser butt welding condition for STS 304 steel, laser bead on plate welding was conducted. After the BOP test, cross-section observation was conducted to analyze the penetration characteristics. After observation, four bead parameters were measured, and these tendency result of laser welding for STS 304 steel can be used as conditions laser butt welding of STS 304 steel.

Nonlinear mechanical behavior and stress amplification effect correction of thin plate welded structure considering initial deformation

With the continuous development of light weight of ships, thin plate welded structures are widely used in superstructure of large hull structures and high-speed boats. However, the thin-plate welded structure has a special nonlinear mechanical behavior because of its small stiffness, more complicated welding deformation. The nonlinear mechanical behavior of thin plate welded structure is mainly caused by large slenderness ratio and complex initial buckling deformation, which can be characterized and quantified by defining global deformation angle αG and local deformation angle αL. Because of the welding angle deformation and welding dislocation, there is obvious stress amplification effect at the welding corner, but the traditional stress amplification correction formula is only suitable for thick plate welding structure. Aiming at the nonlinear mechanical behavior and secondary bending moment effect of thin plate welded structure, an analytical model of thin plate welded structure with initial deformation is established by combining theoretical derivation and numerical method. The results show that the additional bending moment effect caused by local welding deformation angle cannot be ignored. Finally, combined with a series of fatigue tests, the additional bending moment caused by bending deformation and angular deformation of typical welded joints is analyzed, and the notch stress field and fatigue strength correction of thin plate welded structures with initial defects are realized.

Validation of a Theoretical Model for Laser Welding Thermal Field by Multi-Physics Numerical Simulation

Theoretical models based on solutions of the conduction heat transfer equation have been widely proposed to calculate the thermal fields generated during laser welding, revealing simplification benefits and limitations in the accuracy of the results. In previous papers, the authors have introduced a parameterized analytical model based on the configuration of a virtual system of multiple mobile heat sources that simulates the effects of an actual keyhole welding mode by setting the system parameters so as to fit the calculated contours of the fusion zone in the weld cross-section of the experimental one. Even though a basic validation was already carried out by experimental detection, in order to further strengthen the model validity, this article deals with an extensive comparison between the results obtained by a multi-physics numerical simulation, performed by a commercial CFD software, and a theoretical one. The two different approaches were applied to the laser beam welding of butt-positioned AISI 304L steel plates. The investigation was focused on the effects of the keyhole on the main morphological features of the melt pool and fusion zone, and on the thermal fields obtained by the two models. The intrinsic differences between the two approaches, and how they are reflected in the corresponding results, were discussed. Satisfactory results were obtained by comparing the thermal fields, with a substantial convergence of the results, so as to validate the analytical model, assess the accuracy of its results, and define its application limits.

Evaluation of the Ultrasonic Flaw Detector Inspection on Single Vee Butt Welded of Carbon Steel Plate Using Three Different Couplant

Carbon steel plate with single vee butt welded was inspected with an ultrasonic flaw detector (UTFD) using an angle probe. Various types of couplants have been used to study their effects on ultrasonic transmission. The acoustic impedance of the couplant affects the transmission of ultrasonic waves. As a result, welding flaws were found on the root and central area of the butt weld plate. The results also show that honey has the smallest percentage difference (234.42) in terms of size accuracy compared to water (362.89) and baby oil (370.04) in identifying and measuring defect size. However, there are other factors to be considered when performing an UTFD testing. In summary, UTFD is the only method of NDT that can detect and measure all subsurface defects in the weld area, and honey gave the best results for the couplant used.

Economic Feasibility Analysis According to Seam Location of Ship Pieces

The structure of a ship is completed by processing various steel plates and welding these plates. This butt welding of plates is defined as a seam in shipyards, and this study seeks to find a way to decrease costs by reducing the utilization of steel through effective seam arrangement. Seams were defined and classified according to purpose, and examples of “pieces” and “main plates” where seam creation had an economical saving effect were selected. For “pieces,” the change in the weight of steel utilized depending on the presence or absence of a seam was calculated, and the resulting change in cost increase was presented. In the case of the “main plate,” the quantity of seams does not change, but an example of cost variation due to the appropriate placement of seams is presented. Hence, a large difference was found in the costs of “pieces” depending on seam location. Thus, it was advantageous to create additional seams. For the “main plate,” it was found that narrow-width and wide-width materials incur more costs. This study demonstrates that creating seams is economically advantageous but may not be preferred owing to the increased workload from a production perspective.

Penetration State Identification of Aluminum Alloy Cold Metal Transfer Based on Arc Sound Signals Using Multi-Spectrogram Fusion Inception Convolutional Neural Network

The CMT welding process has been widely used for aluminum alloy welding. The weld’s penetration state is essential for evaluating the welding quality. Arc sound signals contain a wealth of information related to the penetration state of the weld. This paper studies the correlation between the frequency domain features of arc sound signals and the weld penetration state, as well as the correlation between Mel spectrograms, Gammatone spectrograms and Bark spectrograms and the weld penetration state. Arc sound features fused with multilingual spectrograms are constructed as inputs to a custom Inception CNN model that is optimized based on GoogleNet for CMT weld penetration state recognition. The experimental results show that the accuracy of the method proposed in this paper for identifying the fusion state of CMT welds in aluminum alloy plates is 97.7%, which is higher than the identification accuracy of a single spectrogram as the input. The recognition accuracy of the customized Inception CNN is improved by 0.93% over the recognition accuracy of GoogleNet. The customized Inception CNN also has high recognition results compared to AlexNet and ResNet.

Influence of Initial Structural Dimensions of Plates on Welding Distortion

Aiming at the complex full-field deformation problem that easily occurs when welding plates, this paper adopts the elastic–plastic finite element method with heat-force coupling to study the deformation law of plates in different initial states. First, a rectangular plate finite element model with an initial radius and Gaussian heat source model was established to obtain the welding temperature field and deformation field of the plate; then, the method based on digital image correlation technology was used to detect the full-field dynamic deformation of the plate to verify the accuracy of the finite element model; finally, the influence of the initial structural dimensions of the plate on the weld deformation was investigated. The study shows the following: the thermoelastic–plastic finite element model proposed in this paper has high accuracy in both static and dynamic deformation; plates with the same curvature, and different lengths and widths of the initial structure of the plate welding deformation are saddle-shaped, and the edge effect of the welding of the plate is evident, independent of the length of the plate; and the maximum out-of-face deformation of the welding of the plate is linearly related to the length and the closer the aspect ratio of the plate is to 1, the smaller the out-of-face deformation is.