Joint Resistance Research Articles

Effect of Alternating Magnetic Field on the Organization and Corrosion Resistance of 2205 Duplex Stainless Steel Narrow-Gap Laser-MIG Hybrid Weld Head

In this study, an alternating magnetic field is applied in the narrow-gap laser-MIG hybrid welding of 2205 duplex stainless steel with a thickness of 25 mm to achieve the purpose of balancing the ration of the two phases, refining the grains and improving the corrosion resistance. With the help of OM, EBSD, TEM, and other microstructural analysis methods, the organization evolution of a 2205 duplex stainless steel narrow-gap laser arc hybrid weld under the effect of alternating magnetic field is revealed. The corrosion resistance of the welded joints is investigated by electrochemical tests. The results show that the use of a 40 mT applied alternating magnetic field can not only effectively inhibit the generation of porosity and unfused defects in the weld, but also that the addition of an alternating magnetic field improves the ratio of austenite to ferrite in the weld, and the ratio of the two phases is increased from 0.657 without a magnetic field to 0.850. The weld grain preferential orientation is affected by the magnetic field, and the weld austenite grains are shifted from the Goss texture to the Copper texture. Under the electromagnetic stirring effect of the applied magnetic field, the average austenite grain size decreased from 4.15 μm to 3.82 μm, and the average ferrite grain size decreased from 4.99 μm to 4.08 μm. In addition, the effect of the alternating magnetic field increases the density of twins in the organization. Electrochemical test results show that the addition of an alternating magnetic field increases the corrosion potential by 75.2 mV and the pitting potential by 134.5 mV, which indicates that the corrosion resistance of the cover-welded specimens is improved by the effect of an alternating magnetic field. The improvement in corrosion resistance mainly depends on the austenite grain refinement and the increase in the austenite content.

Weld size and resistance in rectangular hollow section T-joints

When chord face failure occurs, one of the factors, which influence the resistance of the square hollow sections joint is the brace-to-chord width ratio of the joint. This includes the size of the weld connecting the two members. The influence of weld type and weld size on the behaviour of rectangular and square hollow section joints was studied at the Czech Technical University in Prague.This paper describes an experimental and numerical investigation of square hollow section joints. The welded T-joints were loaded by axial compression. Three different types of welds were investigated - butt welds, fillet welds and a combination of these types. Experimental results for the T-joint together with material characteristics are provided. The paper presents a validation of the numerical model to experimental data. The research-oriented model with shell elements, prepared in RFEM finite element software, represents well the behaviour of square and rectangular hollow section joints. A parametric study with a broader range of sections was performed using the design-oriented shell elements model. Based on the results of the experimental and numerical investigations a modification of the analytical equations used in current prEN1993-1-8:2021 is proposed.

Early effectiveness of arthroscopic repair of supraspinatus tendon tears with douple-pulley suture-bridge

To investigate the early effectiveness of arthroscopic repair of supraspinatus tendon tears with douple-pulley suture-bridge. The clinical data of 38 patients with supraspinatus tendon tears who met the selection criteria between September 2020 and July 2022 were retrospectively analyzed, and all of them were treated with arthroscopic double-pulley suture-bridge technique. There were 15 males and 23 females, aged from 43 to 77 years, with an average of 61.5 years. There were 15 cases of left shoulder and 23 cases of right shoulder. Seven cases had a history of trauma, and the other 31 cases had no obvious inducement. The main clinical symptoms of the patient were pain in lifting the shoulder joint and hug resistance test (+). The time from onset of symptoms to admission ranged from 6 to 19 months, with an average of 10.3 months. Flexion, abduction, and external rotation of the shoulder were recorded before operation and at 3 and 12 months after operation. Pain and function of the shoulder were evaluated by visual analogue scale (VAS) score, University of California Los Angeles (UCLA) shoulder score, and American Society of Shoulder and Elbow Surgeons (ASES) score before operation and at 12 months after operation. Tendon healing, tendon continuity, and tension were evaluated by MRI at 3-6 months after operation, and patient's satisfaction was evaluated at last follow-up. All the incisions healed by first intention, and there was no complication such as incision infection or nerve injury. All patients were followed up 12-34 months, with an average of 23.3 months. VAS score, UCLA shoulder score, and ASES score at 12 months after operation were significantly better than those before operation ( P<0.05). The external rotation range of shoulder joint significantly improved at 3 and 12 months after operation ( P<0.05), and it further improved at 12 months after operation when compared with 3 months after operation ( P<0.05). There was no significant difference in the range of flexion and abduction at 3 months after operation when compared with those before operation ( P>0.05), but the range of flexion and abduction at 12 months after operation significantly improved when compared with those before operation and at 3 months after operation ( P<0.05). MRI reexamination was performed in 28 patients at 3-6 months after operation. Among them, 25 patients had intact supraspinatus tendon structure, good tension, and tendon healing, and 3 patients had type 1 retear. The remaining 10 patients refused to undergo MRI reexamination because of the satisfactory effectiveness. At last follow-up, 29 patients (76.3%) were very satisfied with the results, 6 (15.7%) were satisfied, and 3 (7.8%) were not satisfied. Arthroscopic double-pulley suture-bridge technique can achieve the effect of suture bridge operation, reduce the cost of operation and the risk of type 2 retear, and the early effectiveness is satisfactory, but the shoulder joint movement is limited within 3 months after operation.

Influence of nitrogen content on the pit formation and pit propagation in the welded joints of X5CrNi18‐10 stainless steel

AbstractThe influence of welding current and nitrogen content in argon shielding gas on the resistance of the welded joint (weld metal and heat‐affected zone [HAZ]) of the stainless steel X5CrNi18‐10 to the formation and growth of pits was investigated. Also, the susceptibility of the welded joint to intergranular corrosion was examined. Pitting corrosion resistance indicators were determined based on anodic potentiodynamic polarization measurements in NaCl + Na2SO4 solution, while susceptibility to intergranular corrosion was determined by the potentiokinetic method with a double loop (DL EPR). SEM/EDS was used to analyze the microstructure. It has been shown that higher nitrogen content in shielding gas leads to an increase in the resistance of welded joints (weld metal and HAZ) to the pit formation. However, an improvement in the resistance to the pit formation leads to a decline in the resistance of the welded joint to pit growth. An explanation of this phenomenon is proposed. Also, it was shown that the increase of the welding current increases the susceptibility of the welded joint to intergranular corrosion, while the higher nitrogen content has no effect.

Performance characteristics of REBCO coated conductor joints fabricated by flux-free hybrid welding

Recently, the joining of rare-earth barium copper oxide coated conductor (CC) tapes using ultrasonic welding (UW) has demonstrated outstanding potential in the in-line fabrication of longer tapes required for superconducting device applications. The UW method can produce CC joints by applying ultrasonic vibration in less than one second, and hybrid welding (HW) has been adopted to improve further the joint resistance (R j) and electromechanical properties of the UW CC joints. However, conventional methods for preparing the HW and soldered CC joints involve applying solder flux to remove the oxide film, which can cause corrosion to the surface of the CC tapes and affect the joint’s lifespan during device operation. Therefore, this study aims to fabricate a robust HW CC joint of pre-solder insertion without solder flux and compare its joint strength and electromechanical properties with the traditional cases with the solder flux. While similar R j can be obtained from both cases of HW CC joints, the flux-free HW CC joint has slightly higher joint strength and superior adhesive characteristics than those with flux. The difference in fracture mechanisms after lap-shear and T-peel tests between flux-free HW and with flux was extensively discussed. Additionally, the study investigates the correlation between a decrease in R j with longer joint length in differently stabilized and processed CC tapes for flux-free HW. Overall, this study demonstrated that the flux-free HW method could efficiently produce robust CC joints with a lesser risk of corrosion and enhanced joint characteristics.

A comparative study of microstructure and corrosion resistance in DP980 steel joints under different laser welding method

Three different laser welding methods were used to welding 2 mm DP980 steel butt joint, which were laser welding, laser-TIG hybrid welding and laser powder feeding (CoCrNi) welding respectively. An observational analysis was carried out in terms of microstructure, mechanical properties and corrosion resistance. It was discovered that a central microstructure of laser welding and laser-TIG hybrid welding the weld was dominated by slatted martensite. The laser powder feeding welding has resulted in a remarkable reduction of cylindrical crystals and an increased number of isometric crystals in weld center due to the addition of CoCrNi powder. Microstructure was further refined in incomplete phase transition zone by three different laser welding methods. The tempered martensite was also formed in the tempering zone, which softened the joint. The hardness values decreased considerably and tensile samples were also fractured at this location. Comparison with corrosion resistance of their joints through polarization curves and impedance spectra shows that laser powder feeding joint > laser joint > laser-TIG hybrid joint. The corrosion resistance of laser and laser-TIG hybrid joints in the base metal (BM) > heat affected zone (HAZ) > weld zone (WZ) is shown based on scanning vibrating electrode technique (SVET) localized area testing data at different time intervals. The laser powder feeding welding enhances the density of passivation film by reacting Cr to form Cr2O3, thereby improving corrosion resistance of entire joint.

Angular dependence of resistance and critical current of a Bi-2223 superconducting joint

Low resistance and high critical current are prerequisites for superconducting joints used in persistent-mode magnets. Herein, we use a joint resistance evaluation system, previously developed by us, to systematically evaluate the angular dependence of resistance and critical current of a Bi-2223 superconducting joint in a closed-loop sample. The current decay is measured by rotating the sample incrementally. The time dependence of the loop current is evaluated at 4 K, 0.15–0.28 T, and magnetic field angles ranging from 90° to 0, wherein 90° corresponds to the direction parallel to the tape surface. The results suggest that the resistance and critical current of the joint depend on the angle of the magnetic field. The evaluated critical current increases as the angle increases. The angular dependence of resistance can be divided into three regions: low-resistance, transition, and high-resistance regions. The low-resistance region exists at high angles close to 90°. In this region, the decay of the loop current is small, and the persistent current continues to flow. Furthermore, the joint resistance is less than 1.4 × 10−13 Ω. In the transition region, the joint resistance significantly increases by three orders of magnitude with sample rotation. This significant increase is attributed to an increase in the perpendicular component of the magnetic field, which decreases the critical current of the joint. At lower angles, the joint resistance remains high, ranging from 10−11 to 10−10 Ω. A significant decay in the loop current is observed in the high-resistance region. Based on these findings, we conclude that the design of a persistent-mode magnet must consider not only the magnitude but also the direction of the magnetic field applied to superconducting joints.

Performance Evaluation of Underwater (UW) Welding System with Friction Stir Welding (FSW) Method on 316L Stainless Steel Exposed to Sea Water

Friction Stir Welding (FSW) is a solid-state welding technique that can produce high-quality joints without defects that commonly occur in liquid welding. However, FSW has limitations in underwater applications due to the friction between the tool and the material that causes a decrease in heat efficiency and shear force. To overcome this problem, this study proposes an underwater welding (UW) system with the FSW method on 316L stainless steel exposed to seawater. This UW-FSW system uses a high-speed rotating tool surrounded by an inert gas shroud to prevent direct contact between the tool and seawater. The aim of this study is to evaluate the performance of this UW-FSW system in terms of mechanical properties, microstructure, and corrosion resistance of 316L stainless steel joints. The results of this study show that the UW-FSW system can produce joints with better tensile strength, hardness, and corrosion resistance than conventional FSW. This is due to the rapid cooling, reduction of oxidation, and formation of a thicker passive layer on the joint surface. This study provides a contribution to the development of environmentally friendly and efficient underwater welding technology.

CHARACTERIZATION OF CORROSION BEHAVIOR OF INCONEL 617 WELDED JOINTS USING CMT-GMAW MULTI-CONTROL WELDING

This work addressed the effect of CMT-GMAW multi-control welding of Inconel 617 alloy with different wire feed rates (8.9, 9.4, and 9.9 m/min) on the microstructure, hardness, and electrochemical properties. The weld joints are composed of columnar dendritic structure with cellular crystals. Electron backscattered diffraction (EBSD) study showed equiaxed dendrite at the center of weld metal with growth direction perpendicular to the fusion boundary. The weldments showed diffraction peaks at 43.53[Formula: see text], 50.12[Formula: see text], and 74.82[Formula: see text], and these peaks mainly represent gamma ([Formula: see text]) and gamma prime ([Formula: see text]) phases along with the carbide peaks of Ti (C, N), M[Formula: see text]C6 and M6C. The Base metal (BM) had a lower hardness (232 ± 10 HV[Formula: see text]) and lower corrosion rate (0.212 mpy) than the weld joints. The increase in wire feed rate (WFR) results in the decrease of microhardness (267 ± 5 − 251 ± 6 HV[Formula: see text]) and increase in corrosion rate (1.833-28.140 mpy). The base metal exhibited higher potential ([Formula: see text]) and lower current density ([Formula: see text]) than the weld joints. As wire feed rate (WFR) increases, heat input increases; solidification time increases, grain boundaries coarsen, resulting in a lower grain boundary (GB) density, and hence increased carbide precipitation and segregation in weld zone leading to higher stable anodic current density, which caused corrosion resistance to deteriorating. The BM was more corrosion resistant than the weld joints. The metallurgical and physical changes caused by the welding process affect the corrosion resistance of the weld joints. This leads to the weld metal corroding faster than the base metal.

Common modelling assumptions affect the joint moments measured during passive joint mobilizations

Joint resistance to passive mobilization has already been estimated in-vivo in several studies by measuring the applied forces and moments while manipulating the joint. Nevertheless, in most of the studies, simplified modelling approaches are used to calculate this joint resistance. The impact of these simplifications is still unknown. We propose a protocol that enables a reference 3D inverse dynamics approach to be implemented and compared to common simplified approaches. Eight typically developed children and eight children with cerebral palsy were recruited and underwent a passive testing protocol, while applied forces and moments were measured through a 3D handheld dynamometer, simultaneously to its 3D kinematics and the 3D kinematics of the different segments. Then, passive joint resistance was estimated using the reference 3D inverse dynamics approach and according to 5 simplified approaches found in the literature, i.e. ignoring either the dynamometer kinematics, the measured moments alone or together with the measured tangential forces, the gravity and the inertia of the different segments, or the distal segments kinematics. These simplifications lead to non-negligible differences with respect to the reference 3D inverse dynamics, from 3 to 32% for the ankle, 4 to 34% for the knee and 1 to 58% for the hip depending of the different simplifications. Finally, we recommend a complete 3D kinematics and dynamics modelling to estimate the joint resistance to passive mobilization.

Ultimate strength and fatigue of stiffened welded tubular joints in floating energy production structures

Monotonic and cyclic loading experiments are performed on 1/6-scale stiffened steel joints representing the welded connection between the tubular braces and the vertical cylinders of a prototype offshore floating structure for combined wind-wave energy production. The structural behavior of the welded joints is investigated to determine their ultimate strength under monotonic loading and their fatigue life. The brace-to-cylinder welded connection is full penetration and semi-automatic, whereas the stiffeners are welded to the inner surface of the cylinder with fillet welds. High-frequency mechanical impact post-weld treatment is applied to five specimens. Experimental observations indicate two critical locations for fatigue crack initiation: the crown of the brace-to-cylinder weld and the fillet weld of the central stiffener. These locations are also verified by finite element simulations and fractographic examination of failed specimens. Post-weld treatment improves the fatigue resistance of the welded joints in the high-cycle fatigue domain but has negligible influence on the low-cycle fatigue response of the connection and its monotonic ultimate strength. Finally, one fatigue-cracked specimen is tested under monotonic loading exhibiting structural performance similar to the intact specimens.

A versatile 4K insert for characterization of the superconducting joints.

A multi-coil superconducting magnet is the heart of any modern Magnetic Resonance Imaging (MRI) scanner. The superconducting magnet in MRI produces a highly homogeneous field (±5 ppm) and stable field (<0.1 ppm/h) in its imaging volume. The temporal field stability depends on the electrical resistance of the inter-coil joints and the electrical resistance of the joint between the coil and the superconducting switch. To establish the joint technology, a 4K test rig is required for testing the sample joints. This paper briefly discusses the details of the versatile 4K insert recently developed at IUAC for the characterization of the superconducting joints using the field-decay measurement technique. It can measure the joint resistance up to ∼10-15 Ω in a straight or spiral joint configuration with lengths up to 150mm. The maximum current that can be induced on the test coil is more than 600A for the field-decay measurement. The behavior of the joint resistance can also be studied in the presence of a 1.5T background field. We have characterized many superconducting joints using this versatile 4K insert. The joints between two different conductors can also be studied using this 4K insert. The lowest joint resistance measured is 8 × 10-15 Ω at zero field. The joint resistance is also measured in the presence of the background field.

Characterization of the ankle dynamic joint stiffness as a function of gait speed for overground and treadmill walking.

The ankle dynamic joint stiffness (DJS), defined as the slope of the joint angle-moment plot, measures the resistance of the ankle joint to movement when the foot is in contact with the ground. DJS helps to stabilize the ankle joint, and its characterization helps to identify gait pathology and assist foot prosthesis design. This study analyzes the available gait dynamics data to obtain ankle DJS parameters for population groups according to age, gender, and gait speed for overground and treadmill walking. This study classified the groups into five walking speeds normalized using the Froude number. Herein, 12 ankle DJS parameters were determined. These include four linear segments: controlled plantar flexion (CP), early response phase (ERP), large response phase (LRP), and descending phase (DP), their corresponding turning points, the net mechanical work, the absorbed work, and the loop direction. Ankle dynamics data for 92 individuals was collected from two gait data repositories. The analysis reveals a notable disparity in stiffness values between overground and treadmill gait. Specifically, the CP stiffness is significantly higher for overground gait. In contrast, the DP stiffness displays an opposing pattern, with higher values observed during treadmill walking. A negative stiffness for LRP was found at fast speeds for all groups. The sorted data, analysis tools, and findings of this study are meant to help practitioners design prosthetic and rehabilitation devices based on age, gender, and walking environment at different gait speeds.

Numerical simulation study on shear resistance of anchorage joints considering tensile–shear fracture criterion of 2G-NPR bolt

2G-NPR bolt (the 2nd generation Negative Poisson’s Ratio bolt) is a new type of bolt with high strength, high toughness and no yield platform. It has significant effects on improving the shear strength of jointed rock mass and controlling the stability of surrounding rock. To achieve an accurate simulation of bolted joint shear tests, we have studied a numerical simulation method that takes into account the 2G-NPR bolt's tensile–shear fracture criterion. Firstly, the indoor experimental study on the tensile–shear mechanical properties of 2G-NPR bolt is carried out to explore its mechanical properties under different tensile–shear angles, and the fracture criterion of 2G-NPR bolt considering the tensile–shear angle is established. Then, a three-dimensional numerical simulation method considering the tensile–shear mechanical constitutive and fracture criterion of 2G-NPR bolt, the elastoplastic mechanical behavior of surrounding rock and the damage and deterioration of grouting body is proposed. The feasibility and accuracy of the method are verified by comparing with the indoor shear test results of 2G-NPR bolt anchorage joints. Finally, based on the numerical simulation results, the deformation and stress of the bolt, the distribution of the plastic zone of the rock mass, the stress distribution and the damage of the grouting body are analyzed in detail. The research results can provide a good reference value for the practical engineering application and shear mechanical performance analysis of 2G-NPR bolt.

Hydrogen embrittlement in dissimilar welded joints interfaces – Influence of manufacturing parameters and evaluation of methodologies

The resistance of dissimilar joints to hydrogen was assessed using fracture toughness in an aggressive environment and slow strain rate tests. Six weld joint conditions were evaluated. To determine the distribution of microconstituents and elements along the interfaces, techniques such as optical and scanning electron microscopy, tomography, and nano hardness were employed. The results demonstrated that the susceptibility to hydrogen embrittlement is directly linked to the fraction of discontinuous regions present along the dissimilar interface. Additionally, a critical evaluation of the methodology concerning the positioning of stress concentration at the dissimilar interface was carried out, and alternative approaches were presented.

Precipitation Behavior and Corrosion Properties of Stirred Zone in FSWed AA5083 Al-Mg Alloy after Sensitization

This paper investigated the Mg-rich phase precipitation behavior and the corrosion performance throughout the thickness direction within the stirred zone (SZ) of friction stir welded (FSW) AA5083 alloy after 175 °C/100 h sensitization. For the as-welded SZ, the recrystallized grain size gradually decreased from the top surface (5.5 μm) to the bottom (3.7 μm). The top and bottom of the SZ maintained relatively high levels of deformed grains and accumulated strain induced by either shoulder pressing or pin stirring. After 175 °C/100 h sensitization, 100 nm thick β′-Al3Mg2 precipitates were present along the grain boundaries (GBs) in the SZ. The bottom of the SZ exhibited more continuous precipitates along GBs due to the fine grain size and the large fraction of high-angle grain boundaries (0.724%). Although the as-welded SZ exhibited excellent corrosion resistance, it became extremely vulnerable to intergranular cracking (IGC) and stress corrosion cracking (SCC) after sensitization. The large SCC susceptibility indices of the SZ samples ranged from 66.9% to 73.1%. These findings suggest that sensitization can strongly deteriorate the corrosion resistance of the Al-Mg FSW joint, which is of critical importance for the safety and reliability of marine applications.

Experimental investigation on seismic behavior of the precast shear wall systems with different connection methods under the coupling action of axial tension and cyclic horizontal load

The grouting sleeve connection and lapped steel bars connection are widely used for the connection, while they often require skilled workers, concealed work, and high installation accuracy, and can be expensive and cause significant damage to horizontal construction joints under earthquakes or extreme winds. To address these issues, based on the lap-spliced connection, the angle steel connectors were installed on the precast shear walls and foundation beams to improve the shear resistance and connection performance of horizontal construction joints and reduce construction issues. In practice, shear walls in high-rise structures may experience the coupling action of axial tension and cyclic horizontal load under strong earthquakes or extreme winds, resulting in an unfavorable state of tension bending or tension shear coupling stress for the shear wall systems. As the height-width ratio of these structures increases, there is a significantly increased possibility of shear wall structures experiencing tension bending or tension shear. In this study, five shear walls with different connection methods were manufactured and tested under the coupling action of axial tension and cyclic horizontal load. And the results suggested that the shear resistance of precast concrete shear walls at the horizontal construction joint significantly influenced their seismic performance and concrete damage when subjected to axial tension and cyclic horizontal loads. The precast shear wall system that utilized lapped steel bars and angle steel connectors for connections exhibited the best seismic performance. Additionally, the continuous horizontal construction joint formed by integral prefabrication (containing the edge components) slightly reduced the seismic behavior of the novel precast shear wall system utilizing lapped steel bars and angle steel connectors. The new precast shear wall system utilizing angle steel connectors has the potential to be an effective means of providing seismic resistance in high-rise structures that are subjected to the coupling action of axial tension and cyclic horizontal load.

Double-flush riveting by punching and compression

This paper presents a new double-flush riveting process to fabricate flat lap joints that can be easily integrated in progressive or transfer multistage tool systems. The process is based on a punching-compression sequence and the design methodology combines experimentation and finite element modeling followed by destructive peel testing. Special emphasis is placed on the identification and selection of punch-to-die clearances to produce tapered cut surfaces that are appropriate for subsequent compression of the solid rivets into double-flush riveted lap joints. Results confirm that rivet materials with lower mechanical resistance than the sheet materials allow fabricating double-flush riveted lap joints with flat surfaces on both sides in which the mechanical interlocking in the undercut area is obtained by plastic deformation of the rivets instead of the sheets. The utilization of aluminum sheets and copper rivets allows extending the process scope of application from structural to energy distribution parts in which the electrical resistance of joints is a critical design parameter.

Flexural resistance of 3D cut welded joints between SHS columns and through I‐beams

AbstractSteel structures can be designed according to different framing methods depending on the location of Moment‐Resisting‐Frames (MRFs). In Europe and the United States, one‐way MRFs are widely exploited due to their ability to clearly identify the seismic and gravity frames and limit the use of expensive joints only in MRFs. Furthermore, this is the most appropriate solution if double‐tee columns are adopted since they can provide high strength and stiffness only in the plane orthogonal to their strong axis. Instead, two‐way MRFs are commonly used in Japan; this solution creates 3D seismic structures and requires the selection of columns able to provide enough strength and stiffness along both their axes. This is the reason why tubular columns are usually used in Japan. Nevertheless, the main drawback of this practice is the need to manufacture complex beam‐to‐column connections.In this framework, the recent introduction of 3D Laser Cutting Technology (3D‐LCT) in Civil Engineering provides a way to reduce this complexity. It allows manufacturing quickly 3D cutting shapes with high precision, optimising the welding quantity and costs. Moreover, all the operations are programmed and fully realised by the machine, avoiding any intervention of operators, eliminating human errors, increasing the quality level and saving time. An example of this simplification is given by connections between Square‐Hollow‐Section columns and passing‐through double‐tee beams. Nevertheless, the novelty of this solution represents a limit to its application in practice because no design equations are currently included in common standards.To fill this knowledge gap, this paper investigates the flexural behaviour of SHS columns to passing‐through double‐tee beam connections according to the component method approach. In particular, the study has been carried out through numerical and analytical activities devoted to providing design formulations.

Influence of heat input on the mechanical characteristics, corrosion and microstructure of ASTM A36 steel welded by GTAW technique

The Gas Tungsten Arc Welding process weld for the 4 mm thickness of the ASTM A36 steel plate with varied heat input parameters of 0.608 kJ/mm, 0.900 kJ/mm and 1.466 kJ/mm, respectively. The effect of different heat inputs on microstructure, corrosion, and mechanical characteristics of developed weld joints are examined by three zones: heat-affected zone, welded zone, and base metal zone. The optical microscopic results of weld joints illustrate that fine grain structure leads to enhance welding strength. It is revealed that the increased heat input parameter on the weld joint shows a decreased tensile strength and hardness of the weld joint. The corrosion resistance of the weld joint is evaluated by Potentio-dynamic polarization. It facilitates that the corrosion rate of the weld joint is decreased with increasing heat input, which results indicate the best and worst corrosion micrograph of the polygonal ferrite and ferrite plus polygonal ferrite. However, the weld joint prepared with 0.900 kJ/mm heat input found maximum corrosion resistance.