Double-sided Arc Welding Research Articles

Online welding status monitoring method of T-joint double-sided double arc welding based on multi-source information fusion

In modern manufacturing, double-sided double arc (DSDA) welding brings advantages in properties and efficiency for T-shaped joints. However, the double-side forming makes it difficult to detect the imperfections and ensure weld joint quality, which few studies have covered. Most existing methods deal with single-arc welding with limited sensing sources. To fill the gap, an online welding status monitoring method for DSDA welding is proposed based on the fusion of welding current, arc voltage, arc sound, and weld pool images. In pre-processing, the automatic weld pool region of interest (ROI) detection method based on the lightweight YOLO-L model and the waveform denoising algorithm are designed. In feature engineering, waveform signals are analyzed in both the time and frequency domain. A weld pool feature extractor based on a convolutional neural network (CNN) is proposed with good effectiveness and interpretability. The output feature combination is refined by Fisher-based selection and evaluation. In model building, an ensemble learning model based on three high-fit basic learners is proposed, with an accuracy of 98.538 %. The proposed model shows significant advantages over the single basic classifier and other ensemble methods. Experiments verify high precision and robustness, laying a foundation for accurate real-time monitoring of DSDA welding production.

Experimental and Numerical Investigation of the Thermal and Force Regulation Mechanism of Bypass Coupling Double-Sided Arc Welding Based on 6061 Aluminum Alloy

In this study, 6061 aluminum alloy was proposed for welding using bypass coupling double-sided arc welding (BCO-DASW) to further improve its welding quality and efficiency. To gain insight into the thermal and force regulation mechanism of the BCO-DASW of 6061 aluminum alloy, the dynamic effects of the high-temperature plasma inside the arc with various parameters were fully compared and investigated through the combined method of the physical experiment and the numerical simulation. The thermal flow field of the hybrid arc was analyzed numerically. Furthermore, its working adaptability and mechanical behaviors were studied experimentally. The results show that a single penetration of the 6 mm sheets can be achieved without visible defects when the center offset of the arcs is within 3 mm on both sides of the base metal during BCO-DASW. Through the thermal analysis, it was found that, compared with the MIG process, the introduction of the bypass arc lead to a temperature decrease at the bottom of the hybrid arc due to energy redistribution. Furthermore, through the kinetic analysis, it was found that not only could the level of arc pressure be reduced, but also the action range of the arc pressure could be regulated up to 4.6 mm. The thermal force regulation mechanism worked together to enhance the stability of the molten pool and achieves good joint strength during the BCO-DASW of 6061 aluminum alloy. This research not only has great significance in further improving the welding quality and efficiency of aluminum alloy, but also deeper understanding of the energy regulation mechanism during aluminum alloy welding.

Investigation of angular deformation control for T-joint rib using multi-point constraint method

The circular rib is a crucial component of large pressure vessels, and its cross-section is primarily a T-joint structure. The double-sided arc welding (DSAW) process is an advanced technology for T-joint connection. However, during the T-joint welding process, harmful deformation still occurs in the form of angular deformation, including web and flange angular deformation. This paper proposes an innovative multi-point array constraint method to control the angular deformation of the rib based on the DSAW process for circular ribs. The welding deformation of the T-joint rib under multi-point constraints is studied using both numerical and experimental methods. The results of the numerical and experimental are consistent, with a relative error of no more than 12%. The multi-point constraint method is found to control angular deformation effectively, with the maximum angular deformation of the web not exceeding 1.77 mm and that of the flange not exceeding 0.45 mm after welding and releasing the constraint. The deformation control is significantly better than that of the rigid jig. Moreover, the coupling deformation of the web and flange caused by double-sided heat source and multi-point constraint forms an overall bending deformation. The deformation trend of each welding process is the same, with the main deformation occurring in the stage of releasing the constraint.

Mechanical performance and weldability of HARDOX 450/AISI 430 grade joined by TIG double-sided arc welding

Abstract AISI 430 and HARDOX 450 grades were combined using tungsten inert gas double-sided welding process. Microstructural changes were evaluated with scanning electron microscope, energy dispersive spectrometry, electron back scatter diffraction, elemental mapping, X-ray diffraction analysis. Mechanical diffenrences of welded alloys were determined by tensile, notch impact and microhardness tests. Failure surfaces of tensile samples were examined by SEM. The maximum tensile strength was 513.59 MPa and the impact energy was 77 J at welding speed of 0.01 m min−1 at current of 475 A. The lowest hardness was determined in HAZ due to excessive grain size. Failure exhibited brittle fracture and cleavage planes.

Microstructure and mechanical properties of AISI 304/DUROSTAT 500 steel double-sided TIG welds

Abstract In this study, AISI 304 stainless steel and DUROSTAT 500 steel are combined using TIG double-sided arc welding. Microstructural differences of welded joints were researched by using a scanning electron microscope (SEM), an optical microscope, and electron backscattered diffraction. Mechanical properties of welded joints were investigated by microhardness, notch impact, and tensile tests. In addition, fracture surface morphology was evaluated using a SEM. The current power had a major impress on bead and hourglass shape. Maximum tensile resistance (677 MPa) was achieved at a welding time of 0.21 (m·min−1) at 460 (A) current, and the impact energy (116 J) was obtained. The weld metal consisted 41 wt% cementite, 25 wt% chromium carbide, 20 wt% martensite, and 14 wt% tetrataenite phases. With the increase in the current voltage, both bead and penetration sizes increased.

Prediction of double-sided arc welding deformation based on dynamic heat distribution model and TEP-FE approach

Prediction of double-sided arc welding deformation based on dynamic heat distribution model and TEP-FE approach

Study of features in weld root formation under double-sided synchronized arc welding of vertical joints of steel tanks

It is shown that increase in the welding productivity of vertical joints of storage tanks for oil and oil products can be achieved due to the double-sided synchronized formation of the X-shaped groove. To minimize various disturbances, including variation of gap size and root face dimension, computer engineering analysis is performed, which showed that the formation of root pass during welding with the movement of the electrode down (vertical down) with increased dimension of the root face leads to lack of penetration, but during groove filling with the movement of the electrodes up (vertical up) deep penetration is achieved given the considerable root face dimension. It is defined that during welding of 30 mm thickness plates with root face dimension range from 6 to 8 mm, it is necessary to ensure the root gap dimension range from 1.5 to 3 mm along the entire length of the seam. In this case, the remaining unfilled cross-sectional area of the groove is small, which makes it possible to fill it in during single pass under two-arc double-sided welding. There is area of double-sided synchronized welding modes in which the occurrence probability of typical defects during the formation of the weld root is minimal.

Double-sided arc welding with multiple electrodes of vertical joints of steel tanks

The increase of the welding productivity is still of immediate interest, which in turn requires the development and implementation of more high-performance welding methods that ensure a consistently high quality of welded joints. One of the ways to further increase the productivity of arc welding processes in the construction of tanks is the industrial use of automatic double-sided arc welding with multiple electrodes in separate weld pools. To establish the relationship between the parameters of the welding mode, energy characteristics, as well as the distance between the torches and their angle of inclination relative to the groove, a physical and mathematical model of the production of the welding joint when four arcs participate in pairs from both sides of the joint has been developed. Thus, computer modeling showed that during weld formation with the movement of the electrode down (vertical down), the possibility of supplying each pair of arcs with pulsed current should be taken into account. During groove filling with the movement of the electrodes up (vertical up), their lateral oscillations and delays at the edges should be carried out according to an aperiodic law in order to minimize the effects of ‘magnetic blow’.

Influence of heat input on the intermetallic compound characteristics and fracture mechanisms of titanium-stainless steel MIG-TIG double-sided arc welding joints

The influence of the heat input on the intermetallic compound (IMC) characteristics and the fracture mechanisms of titanium-stainless steel MIG-TIG double-sided arc welding (DSAW) joints using Cu–Si welding wire were studied. The results show that the MIG-TIG DSAW method can effectively control the microstructural characteristics by the heat input regulation. The Ti side interfaces were composed of IMC layers, mainly of Ti–Cu phases, and the thickness of the layers increased with increasing heat input. At the low heat input, the joints fractured at the 304SS side interface, which was embrittled by the straight IMC layer with the brittle TiFeSi and λ, Ti(Fe1-xSix)2 (0-x-0.375) phases. With increasing heat input, the melting of the 304SS reduced the interface brittleness by dispersing the brittle λ phase by softer Fe (s,s) and Cu (s,s) phases. At the high heat input, with the melted zone separated from the base metal, the remain-curved 304SS side interface improved the tensile resistance by increasing the load-bearing area. The fracture occurred at the Ti side interface, which embrittled by the thick IMC layers with a thickness greater than 130 μm. With the increase of the heat input, the joints showed an increase in tensile strength at the 304SS side interface but a decrease at the Ti side interface. The optimal tensile strength of 320 MPa was thus obtained in the joint under intermediate heat input, with a fracture position mixed with the Ti side interface and 304SS side interface.

MIG-TIG double-sided arc welding of copper-stainless steel using different filler metals

Copper-stainless steel joints are achieved with sound double-sided appearances using Cu-based, Cu-Ni-based and Fe-based filler metals. The weld zone in the Cu-based filled joint consists of a uniform structure with the Cu solid solution (s,s) phase. The mixture of immiscible Cu and Fe causes weld segregation to appear in the other two joints. The weld zones with mixed phases in the Cu-Ni-based and Fe-based filled joints show higher impact toughness than the weld zone in the Cu-based filled joint. The maximum tensile strength is obtained from the Cu-based filled joint, which can reach up to 80 % of copper tensile strength. The decreased dislocation density and grain-coarsening under the annealing effect softens the heat-affected zone (HAZ) on the copper side of all three joints, making them a fracture zone during tensile tests. All the joints fracture with a ductile mode, and the plastic deformation concentrates on the softened copper side. The Cu-based filled joint exhibits the highest plastic deformation, which is primarily caused by the large deformation of the weld zone and the large deformation of the Cu base metal caused by the high plasticity of the weld that alleviates the stress concentration.

Ways to improve welding operations in construction of oil product storage tanks

It is shown that in order to further increase the welding rate in the construction of oil product storage tanks, fi rst of all it is necessary to develop and implement high-performance methods for double-sided arc welding of vertical joints. It is noted that the most useful technique to increase the welding rate and the quality of vertical joints on the side walls of the tanks is to replace single-arc automatic welding with multi-arc welding in gas-shielded or gas mixtures. Whereby the method exhibiting the most promise for is the double-sided synchronous welding. In this case, two arcs on the both sides of the workpiece are involved in the weld formation. It is determined that for the formation of technical requirements for the welding process and needed welding equipment, and for their implementation in multi-arc welding of vertical joints, it is necessary to conduct comprehensive study of multiparameter relationship between the double-electrode welding modes and the quality of the welded joints in the construction of oil product storage tanks based on physical and mathematical modeling.

Microstructures and mechanical properties of copper-stainless steel butt-welded joints by MIG-TIG double-sided arc welding

Dissimilar copper/stainless steel metal joints with excellent double-sided forming can be obtained by MIG-TIG double-sided arc welding without grooving and preheating. The joints with welding-brazing and fusion welding modes based on the different joining mechanisms in the SS/weld interface can be found. The brazing stainless steel/weld interface shows a flat morphology, while the fusion SS/weld interface consists of a melted unmixed zone (MUZ) and shows a scraggy morphology. A joint free of cracks and pores can be obtained using the welding-brazing mode, which is attributed to the low heat input during welding and the homogeneous composition in the weld zone. Tensile tests show that fracture occurs at the heat-affected zone (HAZ) at the copper side in all joints, and the optimal tensile strength reaches 229 MPa. All joints exhibit lower tensile strength and larger elongation than the Cu base metal due to softening in the HAZ on the copper side. As the amount of the softening mainly depends on the heat input, the welding-brazing joint with low heat input shows high resistance to softening.

Interfacial microstructure evolution and mechanical properties of TC4 alloy/304 stainless steel joints with different joining modes

TC4 alloy(Ti)/304 stainless steel (SS) plates were butt joined using MIG-TIG double-sided arc welding(DSAW) with copper filler metal. Different joining modes, i.e., brazing mode, welding-brazing mode (Ti welding-SS brazing, SS welding-Ti brazing) and fusion welding mode, were achieved by regulating the welding parameters. The interfacial microstructures and mechanical properties of the joints were investigated. The results show that the interfacial microstructures and mechanical properties are strongly affected by the joining mode.For the joints with brazing mode and Ti welding-SS brazing mode, a straight Intermetallic compound(IMC) layer of Fe-Cu-Si and Ti-Fe-Cu-Si phases was respectively formed at the SS side brazing interface, resulting in the fracture at lower stress; the Ti side brazing and fusion interfaces both mainly consisted of Ti-Cu IMC layer. The joints with SS welding-Ti brazing mode and fusion welding mode led to the curved melted zone containing two phases of Fe(s,s) and Cu(s,s) at the SS side fusion interface. The tensile resistance of the interface was significantly enhanced attributed to the curved morphology and the suppression of the brittle IMCs. The fractures occurred at the Ti side interface, and the tensile strength was determined by the thickness of the reaction layer consisted of the Ti-Cu and Ti-Cu-Fe IMCs. Therefore, the SS welding-Ti brazing joint with a thinner reaction layer shows the maximum tensile strength, which is up to 319 MPa.

Butt brazing of titanium alloys/stainless steel plates by MIG-TIG double-sided arc welding process with copper filler metal

Butt brazing of titanium alloys with stainless steel by MIG-TIG double-sided arc welding (DSAW) process with copper filler metal has been performed. The microstructures and mechanical properties of the joint were investigated. The results show that a butt brazing joint with sound double-sided appearance was achieved. With low heat input of brazing mode and rapid cooling rate of arc welding process, the joint is free of brittle Ti-Fe intermetallic compounds (IMCs). The phase compositions in the joint are TC4/Ti2Cu+TiCu/TiCu+Ti5Si3/Cu+(Ti5Si3+Cu+βTiCu4)/Fe5Si3+(Cu)+FeSi/Fe(s,s)/304ss orderly from Ti6Al4V to 304ss. The average tensile strength of the butt joint reaches 278MPa. Compared with the fusion welding joint, the tensile strength of the arc-brazing joint is significantly increased because of the elimination of Ti-Fe IMCs.

Microstructure and mechanical properties of simulated unaltered coarse grained heat affected zones of 10CrNi3MoV steel by double-sided double arc welding

This paper aims to reveal the influence of different welding conditions on unaltered coarse grained heat affected zones (UACGHAZs) of backing passes by double-sided double gas tungsten arc welding (DSGTAW) of 10CrNi3MoV steel. UACGHAZs were also compared with coarse grained heat affected zones (GGHAZs) of single gas tungsten arc welding (SGTAW). At lower heat input (21.7kJ/cm for each run without preheating), CGHAZ mainly consisted of lath martensite (LM) while UACGHAZs composed of LM and small amount of lath bainite (LB). At higher heat input (33.2kJ/cm for each run with 150°C preheating), the microstructures of CGHAZ were LM and LB. In UACGHAZs, the microstructures would transform from LB+LM+granular bainite (GB) to LB+GB as arc distance (d) decreased. The toughness of UACGHAZs was related to martensite/bainite packet sizes instead of prior austenite grain sizes. At higher heat input, the formation of granular bainite deteriorated the toughness of UACGHAZs and negated the positive effect of LB on toughness. DSGTAW can significantly improve the toughness of coarse grained zones when lower heat input is adopted.

In situ observation and electron backscattered diffraction analysis of granular bainite in simulated heat-affected zone of high-strength low-alloy steel

ABSTRACTIn this study, the formation of granular bainite (GB) which may form in the heat-affected zone of double-sided double arc welding joint was in situ observed. The crystallographic characteristics of GB were also compared with those of microstructure mainly comprising lath bainite (LB). The results show that bainite packets exist at the initial stage of GB transformation and can be distinguished by the distribution of retained austenite and martensite–austenite constituents. The bainite blocks of GB are larger than those of LB which makes both the length and fraction of high-angle grain boundaries in GB less than those of LB which partly lead to the brittleness of granular bainite.

Thermal cycles and its effect on HAZ microstructure and mechanical properties of 10CrNi3MoV steel in double-sided double arc welding

Thermal cycles of heat-affected zones (HAZs) in double-sided double arc welding (DSDAW) were measured in this study. The microstructure and impact toughness of specimens imposing typical thermal cycles of coarse-grained heat-affected zone (CGHAZ) were analysed by using thermal simulation. The results show that the two arcs influenced each other even during the deposition of the fourth layer in each side. Both of the two arcs could reduce the cooling rate of HAZs. Besides, the heating of the rear arc may make HAZ sustain in bainite transformation interval for a long time and lead to the formation of granular bainite which could deteriorate welding joint. To obtain good toughness of joint by DSDAW, the arc distance during filling pass depositing should be properly enlarged to eliminate granular baintie under the premise that the trough temperature (T t) is higher than 200 °C.

Joint Characteristics and Corrosion Properties of Bypass-Current Double-Sided Arc-Welded Aluminum 6061 Alloy with Al–Si Filler Metal

Sheets of aluminum 6061 alloy were welded using bypass-current double-sided arc welding with Al–Si filler wire to investigate the effect of Al–Si intermetallic compounds on the microstructure, microhardness and corrosion behavior of weld joint. Experimental results indicated that the Al4.5FeSi phase in the topside of the weld joint was finer than that in the backside and newly formed phase of Al0.5Fe3Si0.5 was observed in the backside. The formation of reinforcing phases of Al–Fe–Si in the weld improved the microhardness of the weld by about 18%. The corrosion resistance of the weld zone was greater than that of the base metal, while the corrosion current displayed opposite, and the corrosion resistance of the weld region was better than that of the base metal.

Study on MIG-TIG double-sided arc welding-brazing of aluminum and stainless steel

MIG-TIG double-sided arc welding (DSAW)-brazing process was firstly conducted to join aluminum alloy and stainless steel using Al-Si filler metal and Nocolok flux. The joints were made at different welding parameters. The formation and microstructure of the weld interface were investigated. The bonding quality of the joints was examined by standard tensile tests. Based on the results, a sound welding-brazing joint with excellent front and back formation was formed. Compared with conventional welding, the welding heat input of T/M-GSAW was smaller and more uniform along the joint thickness. The thickness of the intermetallic compound layer, equal under the same welding condition, was thinner and altered with the welding heat input. The tensile strength of most joints reached 80MPa and fracture occurred in the HAZ of aluminum.

Microstructure and Low Temperature Toughness of Weld Joints Prepared by Double-sided Submerged Arc Welding for Low Carbon Bainite Steel

The low carbon bainite steel was welded by double-sided submerged arc welding and the microstructure and low temperature toughness of the joints was studied by optical microscope and PSW750 instrumented impact testing machine. The results show that the microstructure of the weld seam consisted of acicular ferrite and granular bainite, however the HAZ shows a microstructure consisted of bainite ferrite and granular bainite. The hardness at HAZ near the weld bond is the highest and then decreases gradually approaching to the hardness of base metal. In comparison to the matrix the weld seam and HAZ show a lower toughness with a ductile brittle transition temperature at-20℃and-60℃ respectively, which may be ascribed to the occurrence of solidification segregation, highly concentrated dislocations and formation of carbon nitrides of alloying elements such as Ti and Mo at grain boundaries etc.in the weld joints during rapid cooling after welding.