Showing papers on "Electric resistance welding published in 2018"
TL;DR: In this paper, the requirements of FSW and its process capability has been highlighted for joining of similar/dissimilar polymeric materials for future prospective, where the FSW is one of the most acceptable welding techniques for production of structural/industrial components.
Abstract: Polymer composites have certain advantages over metals in terms of mechanical as well as metallurgical properties. These can be joined with similar as well as dissimilar polymer composites (subject to certain conditions like glass transition temperature, rheological properties etc.). In last 20-25 years number of techniques and concepts has been developed to offer the possibility of joining of polymeric materials which have similar or dissimilar characteristics. In present scenario mechanical fastening and adhesive bonding is replaced by applying welding concepts like: laser transmission welding, friction stir welding (FSW), ultrasonic welding, hot fusion resistance welding etc. The FSW is one of the most acceptable welding techniques for production of structural/industrial components. In this present work, requirements of FSW and its process capability has been highlighted for joining of similar/dissimilar polymeric materials for future prospective.
105 citations
TL;DR: In this article, the influence of controllable arc bubble on the process stability and microstructural evolution of welded joint under different welding conditions were investigated, including onshore welding, conventional underwater wet welding (UWW), and mechanical constraint assisted UWW (MC-UWW).
48 citations
TL;DR: In this article, the root humping is studied by reviewing previous studies and findings and also by sample examination and process observation by high speed imaging, and a map of methods to optimise weld root topology is presented.
43 citations
TL;DR: In this article, the influence of flow rate and direction on metal transfer mode and molten pool shape in underwater wet flux-cored arc welding (FCAW) process were studied.
42 citations
TL;DR: In this article, a microstructural analysis of friction stir welded AA7075-T6 blanks with high welding speeds up to 3 millimeters per minute was presented.
Abstract: Friction stir welding (FSW) is a cost-effective and high-quality joining process for aluminum alloys (especially heat-treatable alloys) that is historically operated at lower joining speeds (up to hundreds of millimeters per minute). In this study, we present a microstructural analysis of friction stir welded AA7075-T6 blanks with high welding speeds up to 3 M/min. Textures, microstructures, mechanical properties, and weld quality are analyzed using TEM, EBSD, metallographic imaging, and Vickers hardness. The higher welding speed results in narrower, stronger heat-affected zones (HAZs) and also higher hardness in the nugget zones. The material flow direction in the nugget zone is found to be leaning towards the welding direction as the welding speed increases. Results are coupled with welding parameters and thermal history to aid in the understanding of the complex material flow and texture gradients within the welds in an effort to optimize welding parameters for high-speed processing.
38 citations
TL;DR: Friction stir scribe technology, a derivative of friction stir welding, was applied for the dissimilar lap welding of an aluminium alloy and galvanised mild steel sheets as discussed by the authors, and the results showed that the process was more efficient than traditional friction-stir welding.
Abstract: Friction stir scribe technology, a derivative of friction stir welding, was applied for the dissimilar lap welding of an aluminium alloy and galvanised mild steel sheets. During the process, the ro...
38 citations
TL;DR: In this article, the authors present a study on welding aluminium to steel by resistance spot welding, where the steel surface was covered by cold spraying with the layer of aluminium, nickel and nickel-aluminium.
Abstract: Studies on bonding of aluminium alloys to steels are popular because these are structural materials widely used in a variety of industries. However, joining these dissimilar materials is difficult mainly because of the formation of brittle intermetallic compounds. This paper presents a study on welding aluminium to steel by resistance spot welding. Before the welding, steel surface was covered by cold spraying with the layer of aluminium, nickel and nickel–aluminium. This way, instead of the welding of dissimilar materials, the welding of aluminium to aluminium (or nickel) layer pre-deposited on the steel sample was performed. The feasibility of using interlayers for improving the welding of dissimilar materials was tested using SEM, EDX and XRD. Mechanical properties of welds were investigated by microhardness and shear strength tests. The results showed that the coating allowed to decrease hardness in the welding zone and to increase the shear strength of the weld.
37 citations
TL;DR: In this article, an optimized laser beam process was taken to investigate the porosity content and the surface smoothing by applying an electromagnetic field, and the produced weld seams were analyzed in cross-section views, by x-ray imaging and by computer tomography (CT).
37 citations
TL;DR: In this article, a hybrid method was introduced called bending mode ultrasonic-assisted friction stir welding (BM-UAFSW) and its effect under various vibration amplitudes was investigated on the longitudinal residual stress in a cross-section area of 3mm and thickness of 5mm AA6061-T6 plates using contour method.
Abstract: Residual stress can affect the properties and performance of materials. Since it is an important factor in all welding processes, either fusion welding or friction stir welding, thus, novel complementary methods should be integrated with friction stir welding for reduction of residual stress. In this work, a hybrid method was introduced called bending mode ultrasonic-assisted friction stir welding (BM-UAFSW) and its effect under various vibration amplitudes was investigated on the longitudinal residual stress in a cross-section area of 3 mm and thickness of 5 mm AA6061-T6 plates using contour method. The findings indicated that BM-UAFSW can decrease the maximum longitudinal residual stress by up to 24% in relation with the conventional FSW. In addition, the reaction forces along tool axis and macrostructure observation were provided to illustrate the effect of high-frequency bending mode ultrasonic vibrations on the welding force and welding quality. All the results suggest that BM-UAFSW with amplitude of 2 and 3 μm provides the best outcome for the welding of 3 and 5 mm thick joints, respectively.
36 citations
TL;DR: In this article, a bead-on-plate configuration was used to join ferritic-martensitic dual-phase steels without large dimensional distortions, and the optimal welding condition was a nominal laser power of 2.0kW and a welding speed of 150mm/s.
36 citations
TL;DR: In this paper, the authors presented a new thermomechanical model of friction stir welding which is capable of simulating the three major steps of FSW process, i.e., plunge, dwell, and travel stages.
Abstract: This paper presents a new thermomechanical model of friction stir welding which is capable of simulating the three major steps of friction stir welding (FSW) process, i.e., plunge, dwell, and travel stages. A rate-dependent Johnson–Cook constitutive model is chosen to capture elasto-plastic work deformations during FSW. Two different weld schedules (i.e., plunge rate, rotational speed, and weld speed) are validated by comparing simulated temperature profiles with experimental results. Based on this model, the influences of various welding parameters on temperatures and energy generation during the welding process are investigated. Numerical results show that maximum temperature in FSW process increases with the decrease in plunge rate, and the frictional energy increases almost linearly with respect to time for different rotational speeds. Furthermore, low rotational speeds cause inadequate temperature distribution due to low frictional and plastic dissipation energy which eventually results in weld defects. When both the weld speed and rotational speed are increased, the contribution of plastic dissipation energy increases significantly and improved weld quality can be expected.
TL;DR: In this article, a series resistance spot welding was used to join SUS304 and carbon-fibre-reinforced polyamide and modified polypropylene, but not to polyphenylene sulphide.
Abstract: Dissimilar materials joining of SUS304 and carbon-fibre-reinforced plastics consisting of short fibres and thermoplastics was performed. The materials were joined by series resistance spot welding. The electrodes were pressed on the metal plate of the lap joint of metal/carbon-fibre-reinforced plastics. The SUS304 plate was heated by resistance heating, causing the thermoplastic near the interface to melt slightly because of heat conduction. SUS304 could be joined directly to carbon-fibre-reinforced polyamide and modified polypropylene, but not to polyphenylene sulphide. The joining area increased with an increase in the welding current and welding time, so did the tensile shear fracture load. Furthermore, the silane coupling agent treatment of SUS304 was highly effective in increasing the joining strength.
TL;DR: In this article, the effect of temperature exposure on the strength of resistance welded joints is analyzed, and the results showed that the lap shear strength decreased with increasing temperature, except for the region between 50°C and 90°C where it remained constant.
Abstract: In this work, the effect of temperature exposure on the strength of resistance welded joints is analysed. Glass fibre reinforced polyphenylene sulphide (GF/PPS) adherends were joined using the resistance welding technique, using a stainless steel mesh as the heating element. Single lap shear tests were performed at temperatures ranging between −50 °C and 150 °C to evaluate the strength of the welded joints. The results showed that the lap shear strength decreased with increasing temperature, except for the region between 50 °C and 90 °C where it remained constant. Fractography analysis revealed that the main failure mechanism was glass fibre/matrix debonding and the connection between the mesh and the matrix was not the weakest link at the interface of the joint at any temperatures under study. The fibre/matrix interfacial strength and the stress distribution at the joint overlap were identified as the main factors influencing the behaviour of lap shear strength with temperature.
TL;DR: In this paper, an optimization experiment was performed using a factorial design to evaluate the effect of process parameters on the weld temperature, surface and internal quality and mechanical properties of self-reacting friction stir welded aluminum alloy 6061-T6 butt joints.
Abstract: Self-reacting friction stir welding (SR-FSW), also called bobbin-tool friction stir welding (BT-FSW), is a solid state welding process similar to friction stir welding (FSW) except that the tool has two opposing shoulders instead of the shoulder and a backing plate found in FSW. The tool configuration results in greater heat input and a symmetrical weld macrostructure. A significant amount of information has been published in the literature concerning traditional FSW while little has been published about SR-FSW. An optimization experiment was performed using a factorial design to evaluate the effect of process parameters on the weld temperature, surface and internal quality, and mechanical properties of self-reacting friction stir welded aluminum alloy 6061-T6 butt joints. The parameters evaluated were tool rotational speed, traverse speed, and tool plunge force. A correlation between weld temperature, defect formation (specifically galling and void formation), and mechanical properties was found. Optimum parameters were determined for the welding of 8-mm-thick 6061-T6 plate.
TL;DR: In this article, the authors investigated the resistance spot welding (RSW) parameters for an uncoated mild steel sample and two hot-dip galvanized steel samples with different zinc layer thicknesses.
TL;DR: In this article, the effects of welding parameters on microstructures and mechanical properties of the weld are investigated, including grain size and porosity ratio in the disk laser welds firstly decrease, then increase with the increase of the heat input.
TL;DR: In this article, the authors investigated the effect of tool offset in the joining of dissimilar materials by friction stir welding (FSW) process and found that tool offset is one of the most significant parameters in joining dissimilar material by FSW.
Abstract: Tool offset is one the most significant parameters in joining of dissimilar materials by friction stir welding (FSW) process. An investigation is carried out on the effect of tool offset toward the...
TL;DR: In this paper, numerical thermal fields and residual stresses induced by single-pass weld overlay and girth welding in lined pipe using Tungsten Inert Gas (TIG) welding are investigated.
Abstract: This paper investigates numerical thermal fields and residual stresses induced by single-pass weld overlay (lap-weld) and girth welding (butt-weld) in lined pipe using Tungsten Inert Gas (TIG) welding. A distributed power density of the moving heat source based on Goldak’s ellipsoid heat flux distribution is used in a Finite Element (FE) simulation of the lined pipe welding process. In addition, radiation and convection have been incorporated in heat transfer coefficient user-subroutines for the FE code ABAQUS. The 3-D FE model approach has been validated using previous experimental results published for butt-welds of similar sections of carbon-manganese C-Mn steel pipe lined with stainless steel. The FE model has been developed to determine the thermal isotherms and residual stress distributions from weld overlay and girth welding. The use of an inner layer known as a liner has a considerable influence on the thermal history and residual stress distributions. Furthermore, the influence of the weld overlay has been examined thermally and mechanically as it is a key factor that can affect the quality of lined pipe welding.
TL;DR: In this article, the influence of welding heat input on the morphology, interface bonding, mechanical properties and fracture modes of welded joints was systematically analyzed, and it was shown that laser-gas tungsten arc welding with filling wire can be used to combine high-performance joints and Mg/steel dissimilar metals during butt assembly.
TL;DR: In this paper, a metal transfer control method based on pulsed wire feed technology is adopted to ameliorate the underwater flux-cored arc wet welding quality, and the stability of the welding process is improved with appropriate pulse parameters.
Abstract: A metal transfer control method based on pulsed wire feed technology is adopted to ameliorate the underwater flux-cored arc wet welding quality. The stability of the welding process is improved with appropriate pulse parameters. The influences of pulse parameters on the metal transfer process are clarified using an X-ray transmission method. Pulse frequency has more of an effect on weld appearance and welding stability than pulse duty factor. Thirty to forty hertz is an appropriate frequency bound for a stable metal transfer process. The repelled metal transfer percentage decreases with increasing droplet growth speed. The inertia force shortens the metal transfer period and prompts droplet transfer into the pool. When the pulse frequency is less than 40 Hz, the base speed time is long enough for the inertia force to act on the droplet. But if the pulse frequency is below 20 Hz, the peak wire feed speed will be sustained for a long time, and the short-circuit frequency increases from 1 to 2.5 Hz; as a result, the welding stability and the welding appearance deteriorate. For the wire employed in this study, better welding stability is obtained at 30 Hz, while the pulse duty factor is 2.
TL;DR: In this article, a stationary shoulder made of Teflon was used to weld thin plates of polypropylene and polyethylene together in the lap-joint configuration without external heating.
Abstract: There has been a significant increase in the use of polymeric materials in various areas of industry and engineering, which were previously dominated by metallic components. Recently, the possibility of implementing friction stir welding (FSW) technology for welding polymer-polymer and polymer-metal has come under investigation. Polymeric materials behave differently from metallic ones, and there is still a limited number of research works in the literature concerning this specific topic. In this study, a stationary shoulder made of Teflon was used to weld thin plates of polypropylene and polyethylene together in the lap-joint configuration without external heating. Using a stationary shoulder, the probe generates all the frictional heat and stirs the nearly molten material under an axial force. This article is focused on parameter optimisation for friction stir welded lap joints of dissimilar polymers using a new tool concept. It was concluded that the tool design has the most effective role regarding the lap-shear strength of joints. Welds fabricated with the optimised welding parameters present good surface quality and strength. Moreover, for welding polymeric materials with this method, the main defects have been found on the retreating side of the welds. This behaviour can be explained by insufficient heat generation on the retreating side as well as poor thermal conductivity of polymeric materials.
TL;DR: Refill friction stir spot welding (RFSSW) technology was used to weld 2mm-thick 2198-T8 aluminum alloy in this paper, where the effect of the tool rotating speeds on microstructure and mechanical properties of the RFSSW joint was mainly discussed.
Abstract: Refill friction stir spot welding (RFSSW) technology was used to weld 2 mm-thick 2198-T8 aluminum alloy in this work As one of the most significant factors affecting the joint mechanical properties, effect of the tool rotating speeds on microstructure and mechanical properties of the RFSSW joint was mainly discussed Results showed that keyhole could be successfully refilled after the RFSSW process Due to the complicated movement of the tool components, different material flow behaviors could be obtained at the pin affected zone and sleeve affected zone, leading to different microstructures at the two regions By undergoing through different heat cycle during welding, the secondary phase particles (Al2Cu) showed different morphologies and sizes at different regions The lap shear failure load of the joint firstly increased and then decreased with increasing in the rotating speed The maximum failure load of 9298 N was obtained when using 1600 rpm All the joints showed lap-shear fracture mode
TL;DR: In this paper, three different approaches for improving the hot cracking susceptibility of AA2198 laser beam welded without any filler material are presented, including pre-heating of the weld samples to elevated temperatures, preloading of weld samples perpendicular to the welding direction, or an optimization of the laser-beam welding parameters.
Abstract: AA2198 is a relatively new light-weight and high-performance Al-Cu-Li alloy considered for aviation and space applications. However, Al-Cu-Li alloys generally exhibit severe weldability problems for all fusion-welding techniques, such as laser-beam welding. In particular, porosity formation and hot cracking are observed for the laser-beam welding of these alloys. A common remedy for hot cracking is the use of an appropriate filler wire with a high Si content. In the present study, three different approaches for improving the hot cracking susceptibility of AA2198 laser beam welded without any filler material are presented. For this purpose, pre-heating of the weld samples to elevated temperatures, pre-loading of the weld samples perpendicular to the welding direction, or an optimization of the laser-beam welding parameters were conducted. The autogenously welded samples were assessed with regard to the resulting total crack length and their mechanical properties. It was demonstrated that all of the presented approaches led to a reduction of hot cracking. However, the largest effect was observed for the use of low levels of laser power and welding velocity. The mechanical properties of the optimised autogenously welded samples are only marginally inferior as for the samples laser welded with the Al-Si filler wire AA4047.
TL;DR: In this paper, a tungsten inert gas (TIG) and metal inert gases (MIG) hybrid welded joint of type 304 austenitic stainless steel was characterized with incomplete penetration, full penetration and excess penetration of weld.
Abstract: Stainless steel is a family of Fe-based alloys having excellent resistance to corrosion and as such has been used imperatively for kitchen utensils, transportation, building constructions and much more. This paper presents the work conducted on the material characterizations of a tungsten inert gas (TIG)–metal inert gas (MIG) hybrid welded joint of type 304 austenitic stainless steel. The welding processes were conducted in three phases. The phases of welding employed are MIG welding using a current of 170A, TIG welding using a current of 190A, and a hybrid TIG–MIG welding with currents of 190/170A, respectively. The MIG, TIG, and hybrid TIG–MIG weldments were characterized with incomplete penetration, full penetration and excess penetration of weld. Intergranular austenite was created toward transition and heat affected zones. The thickness of the delta ferrite (δ-Fe) formed in the microstructures of the TIG weld is more than the thickness emerged in the microstructures of MIG and hybrid TIG–MIG welds. A TIG–MIG hybrid weld of specimen welded at the currents of 190/170A has the highest ultimate tensile strength value and percentage elongation of 397.72MPa and 35.7%. The TIG–MIG hybrid welding can be recommended for high-tech industrial applications such as nuclear, aircraft, food processing, and automobile industry.
TL;DR: Magnetic pulse welding (MPW) has recently been increasingly investigated for specific dissimilar material joining applications since this is a solid state clean process, with good energy efficiency as mentioned in this paper, and it can be used for a variety of materials joining applications.
Abstract: Magnetic pulse welding (MPW) has recently been increasingly investigated for specific dissimilar material joining applications since this is a solid state clean process, with good energy efficiency...
01 Feb 2018
TL;DR: In this article, a two-dimensional coupled electro-thermo-mechanical finite element model is employed to predict the residual stresses in aluminum alloy 6061-T6.
Abstract: The main purpose of this study is to investigate the effect of sheet thickness on nugget size and residual stresses in resistance spot welding. A two-dimensional coupled electro-thermo-mechanical finite element model is employed to predict the residual stresses in aluminum alloy 6061-T6. The simulation results are compared with the results obtained from the experimental nugget size and the residual stresses are measured by the X-ray diffraction method. The results indicate that the highest tensile residual stress occurs at the center of the nugget and diminish along the nugget radius. The residual stresses increase on increasing the electrical current and reducing the welding time. By increasing the sheet thickness, the affordable range of welding current and welding cycle increase. It also leads to the enlargement of the nugget, which consequently results in the increase of the residual stresses.
TL;DR: In this article, the friction stir welds were submitted to tensile tests indicating an improvement of strength in welded joints, and they were obtained for UNS S32101 and S32205 duplex, S32750 and S32760 superduplex stainless steels.
Abstract: Duplex stainless steels are successful in a variety of applications such as the food industry, petrochemicals and plants for desalination of seawater, where high corrosion resistance and high mechanical strength are required. However, the beneficial microstructure may change during fusion welding steps, and it can compromise the performance of these materials. Friction stir welding is a solid-state process avoiding typical problems concerning solidification such as solidification cracks, liquation and segregation of alloying elements. Superduplex stainless steels can avoid unbalanced proportions of ferrite and austenite, formation of secondary deleterious phases and grain growth of ferrite in the heat-affected zone. Consolidated friction stir welded joints with full penetration 6 mm thick were obtained for UNS S32101 and S32205 duplex and S32750 and S32760 superduplex stainless steels. The friction stir welds were submitted to tensile tests indicating an improvement of strength in welded joints, s...
TL;DR: The pulsed gas tungsten arc welding with hot wire was used to clad Inconel 625 on the surface of X65 steel as discussed by the authors, and the influences of welding current in horizontal welding position on the dilution, in furt...
Abstract: The pulsed gas tungsten arc welding with hot wire was used to clad Inconel 625 on the surface of X65 steel. The influences of welding current in horizontal welding position on the dilution, in furt...
Patent•
06 Mar 2018
TL;DR: In this paper, a three-dimensional detection device and method for scanning the appearance of a welding seam in high-frequency resistance welding based on linear structured light was proposed, which has the advantages of high precision, safety, reliability, real-time detection and the like, improves the efficiency of welding seam quality detection and can achieve automatic detection for the welding seams quality.
Abstract: The invention provides a three-dimensional detection device and method for scanning the appearance of a welding seam in high-frequency resistance welding based on linear structured light. The three-dimensional detection device comprises a linear structured light sensor, a linear displacement transmission system and a computer, wherein the linear structured light sensor comprises a laser, an industrial camera and a fixed panel; and the linear displacement transmission system comprises a base, a stepping motor and a stepping motor controller. A welded object is placed on the base of the transmission system, scanning is performed by adopting the linear structured light, the industrial camera shoots a laser stripe image of the welding seam, the laser stripe image is processed through a software system to obtain three-dimensional point cloud data of the welding seam, appearance characteristics such as the width and the height of the welding seam are acquired through analysis, and thus judgment can be performed on the quality of the welding seam. The three-dimensional detection device has the advantages of high precision, safety, reliability, real-time detection and the like, improves the efficiency of welding seam quality detection and can achieve automatic detection for the welding seam quality.
TL;DR: In this article, the pitting corrosion of ventilation grilles operated in swimming pool environments was confirmed based on the macroscopic and microscopic examinations, and the mechanism of the corrosion was confirmed.
Abstract: This work focuses on the pitting corrosion of ventilation grilles operated in swimming pool environments. The ventilation grille was made by resistance welding of stainless steel rods. Based on the macroscopic and microscopic examinations, the mechanism of the pitting corrosion was confirmed. Chemical composition microanalysis of sediments as well as base metal using scanning electron microscopy and energy-dispersive spectroscopy (SEM-EDS) method was carried out. The weldments did not meet the operating conditions of the swimming pool environment. The wear due to the pitting corrosion was identified in heat affected zones of stainless steel weldment and was more severe than the corrosion of base metal. The low quality finish of the joints and influence of the welding process on the weld metal microstructure lead to accelerated deposition of corrosion effecting elements such as chlorine.