One-side Welding Research Articles

Microstructure and mechanical properties of T-joints in mid-thick Q345 steel plates welded using deep penetration tungsten inert gas welding

The deep penetration tungsten inert gas welding process was first used to realize efficient manufacturing of T-joints. The macroscopic morphology, microstructure, microhardness, and mechanical properties of T-joints were investigated. The welding parameters are a welding current of 465 A, a welding speed of 4 mm/s, and the distance between the tungsten electrode tip and the web plate and flange plate is 2 mm. The one-side welding both sides formation of T-joint was realized under these welding parameters. The Widmanstätten austenite in the web plate's overheated zone hinders the crack’s propagation. The failure crack in the flange plate first propagates in the brittle fusion zone and then propagates in the weld metal. The fracture mode of DP-TIG joints of Q345 steel is mainly brittle fracture. The maximum tensile strength of the joint welded using DP-TIG is 302.15 MPa.

Mechanical properties of one-sided welding for the low-temperature steel using a high-current MAG welding

Mechanical properties of one-sided welding for the low-temperature steel using a high-current MAG welding

THE INFLUENCE OF WELDING TYPE ON THE STRENGTH CHARACTERISTICS OF CONNECTIONS OF REINFORCING BARS WITH A METAL PLATE

Introduction. In reinforced concrete structures, the ends of reinforcing bars are anchored in the concrete by launching the reinforcement beyond the considered section for the length of the force transfer zone from the reinforcement to the concrete as well as by using anchoring devices. If the required design length of the reinforcement cannot be ensured, special measures to anchor the reinforcement bars are applied [1, p. 5.36]. One of these measures is to install special anchoring devices in the form of plates at the ends of the longitudinal bars. When anchoring devices in the form of plates, special attention is paid to the welding type of the plate with the bar, which should prevent the bar from being pulled out when longitudinal forces from external load are applied. Materials and methodology. The material to be investigated was reinforcing bars of class A500C with diameters of 25 and 32 mm, connected at the ends to metal plates by means of contact welding. Holes with a diameter equal to the diameter of the reinforcement were drilled in the metal plates. The bars were inserted into the holes flush with the surface of the plates and welded to the plates by one and double sided welding. A total of two bars were used per welded joint. The strength of welded connection of reinforcing bars with plates was determined on the tensile testing machine HMS-100 by applying maximum tensile force to reinforcing bars. The fracture pattern of each reinforcing bar to plate joint was noted. The results of the experiment. As a result of the experiment, it was found that the destruction of the connection between the two reinforcing bars of 25 mm and 32 mm diameter and the metal plate during one-sided welding occurred by destroying the welding connection and pulling the bars out of the plate. When the bars were joined on both sides, there was no pulling out of the plate. In this case, one 25-mm-diameter bar joint is out of service due to bar breakage in the area of contact with the weld and the other is due to the exhaustion of its physical yield strength. The destruction of the 32mm diameter bars and metal plate joint in the two-sided welding process was due to the rupture of one bar in the area of its contact with the weld and the cracking of the other bar's contact with the weld. Conclusions. As a result of the experiment, it was found that the strength values of the welded connection between reinforcing bars 25 mm and 32 mm in diameter and a metal plate at bilateral welding were 1,33−1,36 times higher than those at one-sided welding.

Analysis of Fatigue Crack Propagation Behavior of Structures with One-Sided Welding in Fillet Welded Joint for Load-Carrying Type

Analysis of Fatigue Crack Propagation Behavior of Structures with One-Sided Welding in Fillet Welded Joint for Load-Carrying Type

Influence of the technological scheme of friction welding with mixing on the structure and properties of aluminum alloy joints

It is shown that the use of various schemes of friction welding with mixing allows to obtain defect-free compounds. At the same time, the joint strength coefficient for the aluminum alloy 1565CHM decreases when switching from a one-sided STP to a STP with a bobbin tool from 0.97—0.99 to 0.90—0.95. For the dispersed-hardened composite material 1565CHM + 20% SiC, the joint strength coefficient is practically independent of the applied technological scheme and is at the level of 0.76—0.83. The average grain size in the seam core of the welded plates of the alloy 1565CHM by one-sided friction welding with mixing is 4.9 ± 1.8 microns. With double-sided STP of 1565CHM alloy plates, the average size in the seam core increases insignificantly to 6.3 ± 1.6 microns. In the case of STP with a bobbin tool, the largest grains in the metal of the seam core with a value of 11.5 ± 1.4 microns are observed.

Reliability improvement of steel storage tanks for phosphoric acid

The paper describes the one-sided welding method for steel structures based on the rational choice of the inverse angle of butt-welded elements of Belgian steel for the manufacture of tank bottom elements of intended for phosphoric acid storage in a construction site. It is shown that the most expedient method for ensuring the design geometry of the tank with a minimum stress of 1.4507 of the material structure, is the bottom sheets preset for welding at a reverse angle of 12 degrees.The proposed method improves the tank reliability for storing aggressive products, its trouble-free and technical safety during the operation. The need is shown for studying the replacement of imported steel by Russian steel to manufacture tanks from alternative nonmetallic materials.

Joint Penetration Monitoring in Low-Frequency Pulsed GTA Root Pass Welding of Medium-Thick Steel Plates

Welder-dependent manufacturing is no longer suitable for the modern production of a high-performance nuclear pressure container. The high-quality root pass welding of medium-thick steel plates is the main challenge to obtain a sturdy reactor vessel, especially to generate one-sided welding with back-formation bead without a backing. Herein, low frequency and large duty-cycle pulsed gas tungsten arc welding (GTAW) was employed to weld the medium-thick steel plates with a 5-mm root face and 2-mm root opening. The arc characteristic and weld pool dynamic behavior in the proposed GTA root pass welding was investigated by a high-speed camera, and a deflection phenomenon of arc tail flame was first found. The correlations of the characteristic parameters of the arc tail flame, including the deflected angle and length, with the weld joint penetration and welding speed were also analyzed in detail. The results showed a negative correlation to the welding speed and a positive correlation with the weld joint penetration. A sound weld bead was formed at a range from 15 deg and 20 mm to 19 deg and 27mm. Based on the above relationship, a new method using these two characteristic parameters was proposed to identify the weld joint penetration in the root pass welding, and its fundamentals were completely demonstrated by the dynamic change of the keyhole. Its feasibility was also demonstrated by the experiment combined with the weld pool dynamic-dependent theoretical analysis.

Closed-loop control of medium-thickness plate arc welding based on weld-face vision sensing

In one-side welding with full penetration, the use of backing strips helps support molten weld metals, but increases manufacturing cycle time and cost. The backing-free welding technology is under investigation for medium-thickness structural components in the aerospace industry. Its crucial challenge is ensuring complete joint penetration and maintaining a suitable and stable backside bead width. This paper presents an innovative method of controlling weld formation based on weld-face vision sensing in arc welding. A standard laser triangulation setup is used to obtain images of weld pool, and a new weld-face feature ‘depression degree of the weld pool’ is proposed. An image processing procedure is developed to extract the depression degree of the weld pool from images in real-time. The depression degree of the weld pool is found to correlate closely with the backside bead width, and is a better indicator of the backside bead width than the weld pool width, with a higher consistency and a smaller time lag. Employing the depression degree as a feedback signal, a backside bead width control method is developed and implemented. Welding experiments on 6-mm-thick aluminum alloy 2219 plates show that the presented method is remarkably effective in achieving full penetration and keeping backside bead width constant.

Development of FEA-ANN-Integrated Approach for Process Optimization of Coaxial One-Side Resistance Spot Welding of Al5052 and CFRP

Abstract Coaxial one-side resistance spot welding (COS-RSW) is a newly developed process for joining metals and composites. In the present study, Al5052 and carbon-fiber-reinforced plastic (CFRP) lap joints were fabricated via COS-RSW. The welding process was modeled numerically using an in-house finite element code called JWRIAN. Single-lap shear tests were performed to evaluate the joining strength. The molten zone diameter was defined and measured experimentally to verify the numerical model. An artificial neural network (ANN) was established based on multitask learning, and its training data set was prepared via finite element analysis (FEA). The well-trained ANN was employed to generate a process window for the COS-RSW. Results demonstrated that the FEA could accurately reproduce the COS-RSW process, which served as an efficient tool for generating a process data set without performing experiments. The ANN performed multitask learning well and predicted the welding output effectively. Furthermore, Tmavg, an index representing the average value of the maximum temperature in the molten interface of CFRP, was adopted to evaluate the contribution of the integral interface temperature field to the bonding strength qualitatively. An optimal Tmavg value, which was close to the CFRP decomposition temperature of 340 °C, was obtained, and it exhibited an excellent correlation with higher bonding strengths. The process window provided welding parameters directly to yield the desired results.

Electromagnetic nature of arc pressure

ABSTRACT The electromagnetic nature of the arc pressure, which is the result of the pinch effect, i.e. compression under the action of its own magnetic field, is confirmed. The pinch effect and compression are greater at the electrode; therefore, powerful plasma flows appear, directed from the electrode to the workpiece, and the pressure of the welding arc is created, which is determined by the current and the contraction coefficient. When welding with a composite electrode the arc pressure is asymmetric with a maximum in the rear part of the active spot, the active spot size increases, the pinch effect decreases. As a result the speed of plasma flows and arc pressure decrease, which ensures high-quality formation of a reverse bead at one-sided high-speed welding on a flux cushion. A process of one-sided high-speed welding by using a composite electrode is developed. This process provides a fourfold decrease in the speed of plasma flows and arc pressure in comparison with a wire electrode, high-quality formation of seams on a flux cushion with fine-grained glassy flux and an increase in the impact strength of welded joints by 2–2.5 times.

Forming characteristics and mechanism of double-sided heat source synergic vertical welding on an aluminum alloy

Top-quality aluminum alloy weld beads, exploiting the double-sided heat source synergic welding (DSHSSW) process, were obtained with medium heat input, no arc spacing, no root gap, and upward vertical direction. The energy utilization was reduced with the augmented arc spacing because of the attendant increased heat dissipation. Compared with one-side welding (OSW), the fusion area and melting efficiency of DSHSSW were enormously raised, indicating the enhancement of melting performance and energy utilization, and superior joints could be fabricated using DSHSSW under the identical heat input. Additionally, the DSHSSW arc was constricted and thus improved the energy density in contrast to OSW. As the weld penetration deepened during DSHSSW, the heat conduction space was diminished, and the heat accumulation effect was generated. The arc contraction and heat accumulation effect mutually lead to the increased penetrating ability during DSHSSW.

One-sided high-speed welding of pipes for gas and oil pipelines by a composite elec-trode

One-sided high-speed welding of pipes for gas and oil pipelines by a composite elec-trode

Welding current magnetic field regulation at high-speed one-sided welding of the pipes for gas and oil pipelines

One-sided high-speed pipe welding for gas and oil pipelines is an energy and material saving process, the use of which is restricted by the magnetic blow and the violation of the external and internal welds formation. Therefore, the development of the one-sided high-speed pipe welding for gas and oil pipelines process, which ensures the magnetic blow prevention, stability, improving the welded joints quality and toughness, is an important scientific and technical problem. According to the magnetism quantum theory, any system with the help of radiation or another method always comes to the lowest or principal state, with an eigen value of energy equal to E0. It has been established that the magnetic blow is the result of the minimum energy law, according to which the arc deviates to the side of a lower magnetic field until the break, as a result of which the process stability and the welds formation quality are violated. When welding pipes for gas and oil pipelines, the magnetic blow increases significantly due to of the magnetic field lines concentration in the ferromagnetic pipe with high magnetic permeability, which results in increased magnetic blow and the violation of both the process stability and the welds formation. To prevent the magnetic blow, welding pipes with two-sided current supply and regulating the welding current magnetic field process by passing current in front and behind the arc has been developed, which ensures the arc equilibrium, reducing the magnetic field energy to zero, stability and improving of the welded joints quality. Оne-sided high-speed welding pipes for gas and oil pipelines method with two-sided current supply and the welding current magnetic field regulation by transmitting current behind and in front of the arc in a ratio I1/I2 = 1,7-1,9, that ensures the magnetic blow prevention, arc balance, process stability, fine-grained microstructure, the welded joints quality and impact strength improving has been developed

Prediction of Fusion Hole Perforation Based on Arc Characteristics of Front Image in Backing Welding.

In one-side welding with back-formation, the weld is penetrated after the fusion hole is perforated. Therefore, judging whether the fusion hole is perforated is very important to realize autocontrol of penetration in one-side welding with back-formation process. Previous researches mainly focused on the morphological characteristics of the molten pool and fusion hole to judge the weld penetration state. Sometimes it is difficult to obtain the morphological characteristics of the molten pool, keyhole and fusion hole and image processing is complex. In this paper, a visual detection system of fusion holes based on visual sensing is constructed to obtain the real-time fusion hole images in backing welding. It is found that the arc characteristics in the front images contain abundant information about the perforation of fusion hole. An image processing program is developed based on MATLAB software, and the arc characteristic parameters in front images are obtained. Taking the arc characteristic parameters as the input, obtaining the penalty function and the kernel function parameters through the cross validation and grid search method, a prediction model of fusion hole perforation based on the support vector machine is put forward. The accuracy for prediction samples is 88%. By analyzing the misidentified samples, it is found that some of the newly perforated images are predicted as nonperforated ones, which has little influence on the penetration control of the weld.

Regulation of the welding current magnetic field during electric arc welding of pipes

ABSTRACT Mathematical models of magnetic field induction at welding plates and pipes are obtained. The influence of the product shape on induction is established by experiment-calculated way. Magnetic blast during pipe welding increases by more than 10 times due to the concentration of magnetic field lines in a ferromagnetic pipe with high magnetic permeability, the increase in induction by π (3.14) times, the electromagnetic force, acting on an arc and magnetic pressure. A method of one-sided high-speed welding of pipes is developed. In such a case, by passing a current opposite to the welding current inside a ferromagnetic pipe, the magnetic blast is prevented, the process stability is enhanced, upward electromagnetic force and magnetic pressure are created that keep the liquid metal from flowing out of the bath. It ensures the formation of quality seams on a flux cushion and an increase in the impact strength of welded joints by 2–2.5 times.

Construction plate enforced by metamaterial elements

This research proposes new metal structural elements based on metamaterials as a replacement of conventional enforcement bars, which reduce metal consumption and increase stiffness and strength. Modern manufacturing machines based on lasers has a capability of fast one-side welding. This type of machines are standard now, what makes this procedure fast and cheap. Another aspect of the nowadays usage of metamaterials for construction works is the possibility to model them with all small details. Ten or twenty years ago modelling of numerous small elements covered by concreate was too expensive, even for one slab not to mention the whole building or a bridge. This work demonstrates one variant of metal reinforcement of concreate plate based on pyramid type elements. This type of pyramid reinforcements was inspired by the analysis of topology optimization of maximum stiffness of structure in case of bending. It was shown numerically, that under condition of three point bending such kind of plate has up to two times higher strength capabilities then conventional plate with equivalent metal consumption.

Visualizing the influence of process parameters on fusion hole behavior in tungsten inert gas welding of thin plates with reserved gaps

In one-side welding with back-formation with a reserved gap, the weld quality largely depends on the stability of the fusion hole. Therefore, the influence of welding process parameters on fusion hole behavior must be analyzed to realize the quality control for this type of welding. In this study, a low-cost dual camera visual sensing system is designed to conduct real-time synchronous monitoring of backside and topside fusion hole behavior and obtain clear images of the backside and topside of a fusion hole. A series of wire-filling tungsten inert gas welding tests with a reserved gap for 3 mm thick 304 stainless-steel test pieces were performed. According to the fusion hole behavior, the welding process was divided into three stages: blind fusion hole stage, fusion hole growth stage and stable fusion hole stage. Moreover, the influence law of the main process parameters (i.e. welding current, welding speed and reserved gap) on fusion hole behavior was explored. The results lay a solid foundation for fusion hole control and optimization in one-side welding with back-formation with a reserved gap.

Behavior of the Fusion Hole in Tungsten Inert Gas Thin-Plate Welding

One-side welding with back formation technique is widely used in pressure vessels and the pressure piping industry. Welders provide high importance to the role of the fusion hole in this type of welding. Therefore, the formation and instability of the fusion hole should be studied to realize the welding automation of the one-side welding with back formation process. A visual sensing system is established to capture the image of the fusion hole, and the behavior of the fusion hole is investigated. Results show that the typical process of the fusion hole includes formation, growth, and macroquasisteady state. The welding parameter scoop to obtain the stable fusion hole is narrow. After deviating from the appropriate parameter scoop, the fusion hole will enter unstable states, thereby resulting in the “fusion hole effect” failure of the welding process. Depending on the change in the shape of the fusion hole, instability types of the fusion hole can be divided into longitudinal, lateral, and gradual shrinking instability. Different instability types correspond to different changing laws of fusion hole morphology. The instability characteristics of the fusion hole can provide effective early warning information before the “fusion hole effect” failure.

One-Sided Resistance Spot Welding of Plastic-Metal Hybrid Joints - Characterization of the Joining Zone

Polymer-metal-hybrid components show a high potential regarding to lightweight applications. In particular, due to their fundamental differences in chemical and physical properties, new approaches must be developed for common industrial joining processes. In this study a new approach in order to characterize the joining zone formation for thermal direct joining based on resistance spot welding is reported. The feasibility of joining in half-section set-up using a coaxial electrode arrangement was investigated. The impact of the welding parameters on the joining zone formation was investigated. The parameters influencing the melting layer formation were pointed out.

Analysis evaluation study on the fatigue crack propagation behavior of the structures with one-sided welding of the fillet welded joint for load carrying type.

Analysis evaluation study on the fatigue crack propagation behavior of the structures with one-sided welding of the fillet welded joint for load carrying type.