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Showing papers on "Arc welding published in 2019"


Journal ArticleDOI
TL;DR: It is shown that AA7075 can be safely arc welded without hot cracks by introducing nanoparticle-enabled phase control during welding by adding nanoparticles to a weld filler rod.
Abstract: Lightweight materials are of paramount importance to reduce energy consumption and emissions in today's society. For materials to qualify for widespread use in lightweight structural assembly, they must be weldable or joinable, which has been a long-standing issue for high strength aluminum alloys, such as 7075 (AA7075) due to their hot crack susceptibility during fusion welding. Here, we show that AA7075 can be safely arc welded without hot cracks by introducing nanoparticle-enabled phase control during welding. Joints welded with an AA7075 filler rod containing TiC nanoparticles not only exhibit fine globular grains and a modified secondary phase, both which intrinsically eliminate the materials hot crack susceptibility, but moreover show exceptional tensile strength in both as-welded and post-weld heat-treated conditions. This rather simple twist to the filler material of a fusion weld could be generally applied to a wide range of hot crack susceptible materials.

176 citations


Journal ArticleDOI
TL;DR: Wang et al. as discussed by the authors proposed a deep learning-based on-line defect detection for aluminum alloy in robotic arc welding using convolutional neural networks (CNN) and weld images.

139 citations


Journal ArticleDOI
24 May 2019
TL;DR: In this paper, the effects of the welding process on buildup accuracy and material properties during wire arc additive manufacturing of aluminum structures were analyzed in terms of surface finishing, hardness, and residual stress.
Abstract: An increasing demand for flexibility and product integration, combined with reduced product development cycles, leads to continuous development of new manufacturing technologies such as additive manufacturing. Wire and arc additive manufacturing (WAAM) provides promising technology for the near net-shape production of large structures with complex geometry, using cost efficient production resources such as arc welding technology and wire materials. Compared to powder-based additive manufacturing processes, WAAM offers high deposition rates as well as enhanced material utilization. Because of the layer-by-layer built up approach, process conditions such as energy input, arc characteristics, and material composition result in a different processability during the additive manufacturing process. This experimental study aims to describe the effects of the welding process on buildup accuracy and material properties during wire arc additive manufacturing of aluminum structures. Following a process development using pulse cold metal transfer (CMT-P), linear wall samples were manufactured with variations of the filler metal. The samples were analyzed in terms of surface finishing, hardness, and residual stress. Furthermore, mechanical properties were determined in different building directions.

82 citations


Journal ArticleDOI
Runquan Xiao1, Yanling Xu1, Zhen Hou1, Chen Chao1, Shanben Chen1 
TL;DR: An adaptive feature extraction algorithm based on laser vision sensor that has good adaptability for multiple typical welding seams and can maintain satisfying robustness and precision even under complex working conditions is proposed.
Abstract: Intelligent robotic welding is an indispensable part of modern welding manufacturing, and vision-based seam tracking is one of the key technologies to realize intelligent welding. However, the adaptability and robustness of most image processing algorithms are deficient during welding practice. To address this problem, an adaptive feature extraction algorithm based on laser vision sensor is proposed. According to laser stripe images, typical welding seams are classified into continuous and discontinuous welding seams. A Faster R-CNN model is trained to identify welding seam type and locate laser stripe ROI automatically. Before welding, initial welding point is determined through point cloud processing to realize welding guidance. During seam tracking process, the seam edges are achieved by a two-step extraction algorithm, and the laser stripe is detected by Steger algorithm. Based on the characteristics of two kinds of welding seams, the corresponding seam center extraction algorithms are designed. And a prior model is proposed to ensure the stability of the algorithms. Test results prove that the algorithm has good adaptability for multiple typical welding seams and can maintain satisfying robustness and precision even under complex working conditions.

70 citations


Journal ArticleDOI
TL;DR: In this paper, a Ni-based superalloy wire, i.e., Inconel 625, is melted and deposited additively through a cold metal transfer (CMT)-based WAAM process.
Abstract: Wire + arc additive manufacturing (WAAM) is a versatile, low-cost, energy-efficient technology used in metal additive manufacturing. This WAAM process uses arc welding to melt a wire and form a three-dimensional (3D) object using a layer-by-layer stacking mechanism. In the present study, a Ni-based superalloy wire, i.e., Inconel 625, is melted and deposited additively through a cold metal transfer (CMT)-based WAAM process. The deposited specimens were heat-treated at 980 °C (the recommended temperature for stress-relief annealing) for 30, 60, and 120 min and then water quenched to investigate the effect of heat treatment on microstructure and phase transformation and to identify the optimum heat treatment condition. Microstructural results show that the heat treatment, in general, eliminates the brittle Laves phases regardless of the time without changing the grain morphology. However, an increment in the amount of the delta phase is observed with the longer heat treatment periods. Additionally, the size of MC (metal carbide) of Nb is also observed to increase with heat treatment time. This study provides an in-depth understanding of the correlation between heat treatment time and microstructure in additively manufactured Inconel 625, which can facilitate determining the optimum heat treatment condition in a later study.

62 citations


Journal ArticleDOI
TL;DR: From the soft computing modeling results, it has been observed that the HPSOSA improved the process performance and has revealed the global optimal solution within minimum interval of time.
Abstract: Recently, the pulsed current tungsten arc welding process (PC-TAW) has cemented their potential in various sorts of industrial application such as automobile, aerospace, and structural joining. However, the involvement of multiple process parameters in PC-GTAW process usually makes the process cumbersome to understand; and thereby, it is difficult to develop the mathematical model. Here, in this scientific work, the major efforts have been made to optimize multiple parameters for selected output responses through the use of evolutionary computational approaches. For this purpose, the particle swarm optimization (PSO), simulated annealing (SA) algorithm, and hybrid PSO-SA (HPSOSA) techniques have been employed and compared in terms of the quality responses for input parameters. From the soft computing modeling results, it has been observed that the HPSOSA improved the process performance and has revealed the global optimal solution within minimum interval of time. The developed models were statistically significant at 95% confidence interval. The experimental and mathematical outcomes for the welded specimens are duly supported with microscopic analyses.

53 citations


Journal ArticleDOI
Lei Yang1, En Li1, Long Teng1, Junfeng Fan1, Zize Liang1 
TL;DR: Faced with the low efficiency of the line-structured light and the poor robustness of passive vision, the seam extraction based on a point cloud processing algorithm is proposed which could well adapt to the weld seams with different types and different groove sizes.
Abstract: With the rapid development of computer vision and industrial technology, the requirements of the intelligent welding robots are increasing in the real industrial production. The traditional teaching-playback mode and the off-line programming mode cannot meet the automation demand and self-adaptive ability of welding robots. In order to improve the efficiency of welding robots, this paper proposes a novel 3-D path extraction method of weld seams based on a stereo-structured light sensor. Faced with the low efficiency of the line-structured light and the poor robustness of passive vision, the seam extraction based on a point cloud processing algorithm is proposed which could well adapt to the weld seams with different types and different groove sizes. Meanwhile, the position information and pose information of weld seam are established to serve 3-D path teaching of a welding robot. The experimental results show that the maximum path extraction error of V-type butt joint is less than 0.7 mm. The proposed scheme could well serve for the 3-D path teaching task before welding.

52 citations


Journal ArticleDOI
TL;DR: In this article, 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.

51 citations


Journal ArticleDOI
TL;DR: In this article, the effect of joint shape geometry on properties of Hadfield steels welded via Shield Metal Arc Welding (SMAW) was studied, including fracture toughness, tensile strength, hardness and corrosion behavior.
Abstract: Effect of joint shape geometry on properties of Hadfield steels welded via Shield Metal Arc Welding (SMAW) was studied. Fracture toughness, tensile strength, hardness and corrosion behavior were ex...

45 citations


Journal ArticleDOI
TL;DR: In this paper, welding of P92 steel and 304H austenitic stainless steel (304H ASS) plates was performed using activated flux-gas tungsten arc welding (activated flu...
Abstract: In the present study, welding of P92 steel and 304H austenitic stainless steel (304H ASS) plates (thickness: 8 mm) was performed using activated flux-gas tungsten arc welding (activated flu...

43 citations


Journal ArticleDOI
TL;DR: In this paper, a 3D print device equipped with a cold metal transfer welding source was used to simulate the formation of 3D microstructures of aluminium deposits. And the effects of the travel speed and layer superposition on the transfer mechanisms as well as on the geometrical characteristics of the deposits were discussed for both sets of parameters.
Abstract: 4043 aluminium deposits were elaborated using a 3D print device equipped with a Cold Metal Transfer welding source. Two sets of process parameters leading to different average powers were compared in order to establish the relations between the powers and energies produced and the geometrical characteristics of the deposits. The effects of the travel speed and layer superposition on the transfer mechanisms as well as on the geometrical characteristics of the deposits were discussed for both sets of parameters. Finally, the formed microstructures were analysed and the porosity defects were quantified and discussed with regard to the heat input characteristics and the solidification conditions.

Journal ArticleDOI
TL;DR: Wang et al. as mentioned in this paper proposed an on-line defect detection method for aluminum alloy in robotic arc welding based on random forest and arc spectrum, which can achieve better performance in identifying three typical defects, including incomplete penetration, burn-through and porosity.

Journal ArticleDOI
16 Nov 2019
TL;DR: In this article, the effect of cooling time on the critical HAZ areas of single and multipass welded joints was analyzed in a Gleeble 3500 physical simulator and thermal cycles were determined according to the Rykalin 3D model.
Abstract: When the weldability of high strength steels is analyzed, it is the softening in the heat-affected zone (HAZ) that is mostly investigated, and the reduction of toughness properties is generally less considered. The outstanding toughness properties of quenched and tempered high strength steels cannot be adequately preserved during the welding due to the unfavorable microstructural changes in the HAZ. Relevant technological variants (t8/5 = 2.5–100 s) for arc welding technologies were applied during the HAZ simulation of S960QL steel (EN 10025-6) in a Gleeble 3500 physical simulator, and the effect of cooling time on the critical HAZ areas of single and multipass welded joints was analyzed. Thermal cycles were determined according to the Rykalin 3D model. The properties of the selected coarse-grained (CGHAZ), intercritical (ICHAZ) and intercritically reheated coarse-grained (ICCGHAZ) zones were investigated by scanning electron microscope, macro and micro hardness tests and instrumented Charpy V-notch pendulum impact tests. The examined HAZ subzones indicated higher sensitivity to the welding heat input compared to conventional structural steels. Due to the observed brittle behavior of all subzones in the whole t8/5 range, the possible lowest welding heat input should be applied in order to minimize the volume of HAZ that does not put fulfillment of the allowed maximal (450 HV10) hardness at risk and does not lead to the formation of cold cracks.

Journal ArticleDOI
14 Aug 2019
TL;DR: In this article, the authors evaluated the environmental behavior of low carbon steel (ER70S-6) produced by a relatively inexpensive additive manufacturing (AM) process using wire feed arc welding.
Abstract: Current additive manufacturing (AM) processes are mainly focused on powder bed technologies, such as electron beam melting (EBM) and selective laser melting (SLM). However, the main disadvantages of such techniques are related to the high cost of metal powder, the degree of energy consumption, and the sizes of the components, that are limited by the size of the printing cell. The aim of the present study was to evaluate the environmental behavior of low carbon steel (ER70S-6) produced by a relatively inexpensive AM process using wire feed arc welding. The mechanical properties were examined by tension testing and hardness measurements, while microstructure was assessed by scanning electron microscopy and X-ray diffraction analysis. General corrosion performance was evaluated by salt spray testing, immersion testing, potentiodynamic polarization analysis, and electrochemical impedance spectroscopy. Stress corrosion performance was characterized in terms of slow strain rate testing (SSRT). All corrosion tests were carried out in 3.5% NaCl solution at room temperature. The results indicated that the general corrosion resistance of wire arc additive manufacturing (WAAM) samples were quite similar to those of the counterpart ST-37 steel and the stress corrosion resistance of both alloys was adequate. Altogether, it was clearly evident that the WAAM process did not encounter any deterioration in corrosion performance compared to its conventional wrought alloy counterpart.

Journal ArticleDOI
10 Jun 2019
TL;DR: In this article, the microstructure, hardness, and tensile strength of a wire and arc additive manufacturing (WAAM) part were studied for the on-demand production of heavily loaded aerospace components.
Abstract: Wire and arc additive manufacturing (WAAM) is a 3D metal printing technique based on the arc welding process. WAAM is considered to be suitable to produce large-scale metallic components by combining high deposition rate and low cost. WAAM uses conventional welding consumable wires as feedstock. In some applications of steel components, one-off spare parts need to be made on demand from steel grades that do not exist as commercial welding wire. In this research, a specifically produced medium carbon steel (Grade XC-45), metal-cored wire, equivalent to a composition of XC-45 forged material, was deposited with WAAM to produce a thin wall. The specific composition was chosen because it is of particular interest for the on-demand production of heavily loaded aerospace components. The microstructure, hardness, and tensile strength of the deposited part were studied. Fractography studies were conducted on the tested specimens. Due to the multiple thermal cycles during the building process, local variations in microstructural features were evident. Nevertheless, the hardness of the part was relatively uniform from the top to the bottom of the construct. The mean yield/ultimate tensile strength was 620 MPa/817 MPa in the horizontal (deposition) direction and 580 MPa/615 MPa in the vertical (build) direction, respectively. The elongation in both directions showed a significant difference, i.e., 6.4% in the horizontal direction and 11% in the vertical direction. Finally, from the dimple-like structures observed in the fractography study, a ductile fracture mode was determined. Furthermore, a comparison of mechanical properties between WAAM and traditionally processed XC-45, such as casting, forging, and cold rolling was conducted. The results show a more uniform hardness distribution and higher tensile strength of the WAAM deposit using the designed metal-cored wires.

Journal ArticleDOI
TL;DR: In this paper, the fusion zone microstructure and mechanical properties of UNS S32750 joints obtained from gas tungsten arc (GTA), GMA and flux cored arc (FCA) welding processes were investigated.

Journal ArticleDOI
05 Jun 2019
TL;DR: In this paper, the effect of constant and pulse arc TIG welding processes, the development of thermal fields and residual stresses in dissimilar weldments of SS 316 and Monel 400 are investigated.
Abstract: Welding residual stresses can predominantly damage the reliability and performance of the welded structures. In this experimental study the effect of constant and pulse arc TIG welding processes, the development of thermal fields and residual stresses in dissimilar weldments of SS 316 and Monel 400 are investigated. During the welding process, the temperature distribution over the surface of the weldments has been captured using Infra-Red Thermography. The developed residual stresses have been measured experimentally by using the x-ray diffraction technique. The nature of residual stresses in constant and pulse arc weldments have been observed and compared. The experimental results of constant current weldments are validated against finite element analysis using ANSYS software. Transient thermal analysis is performed to determine heat dissipation during the welding process in different modes such as conduction, convection and radiation. Also, the elemental birth and death techniques are considered for the effect of filler wire owing simulation. From the results, the experimental and numerical analysis of constant arc welding process show good agreement to each other in temperature fields and residual stresses.

Journal ArticleDOI
Guoliang Qin1, Zhiyong Ao1, Yong Chen1, Cunsheng Zhang1, Peihao Geng1 
TL;DR: In this paper, an Al alloy plate was successfully lap-joined to galvanized steel plate by pulsed metal inert gas (MIG) arc welding with Al-Si filler wire.

Journal ArticleDOI
TL;DR: In this paper, a comparative study of the Stellite 21 hardfacing on H13 steel produced by cold metal transfer (CMT) process and conventional plasma transferred arc welding (PTAW) process was carried out.
Abstract: A comparative study of the Stellite 21 hardfacing on H13 steel produced by cold metal transfer (CMT) process and conventional plasma transferred arc welding (PTAW) process was carried out The lower heat input of the CMT process resulted in finer microstructure and lesser dilution in the Stellite 21 coating than the PTAW process The volumetric dilution values showed much scatter across the thickness of the PTAW coating than CMT The effect of lower dilution and finer structure of the CMT coating resulted in a marginal increase in the microhardness The room temperature (RT) and high temperature (600 °C) wear performance of the coatings were studied using a ball-on-disc tribometer using alumina ball The wear tracks were analyzed using an optical profilometer and the volume loss was calculated The CMT deposited coating showed better wear performance than PTAW coating X-ray diffraction (studies of the room temperature wear tracks showed the transformation of γ-fcc phase in the as-deposited coating to e-hcp phase after the wear The volume percentage of the e-hcp was observed higher for CMT deposited coating than the PTAW coatings, which can be attributed to lower dilution and finer microstructure of the former


Journal ArticleDOI
TL;DR: In this article, the authors present a critical review of the thermal and structural modeling of the arc welding process, showing that high temperature in the welding zone leads to high structural degradation.
Abstract: This paper presents a state-of-the-art critical review of the thermal and structural modelling of the arc welding process. During the welding process, high temperature in the welding zone leads to ...

Journal ArticleDOI
TL;DR: In this paper, the synergy effect between laser and arc enables laser-arc hybrid welding to acquire obvious advantages of efficiency and quality in welding aluminum alloys, but the influence of physical essence of the synergy effects on welding process were not clear.
Abstract: Researchers generally believe that synergy effect between laser and arc enables laser-arc hybrid welding to acquire obvious advantages of efficiency and quality in welding aluminum alloys. However, influences of physical essence of the synergy effect on welding process were not clear. In this study, basic principle of the synergy effect and its influences on welding process were obtained by spectral analysis of hybrid plasma plume and high-speed photographic analysis of welding process. First, the principle of the synergy effect is that laser interacts with arc to render electron energy level to transition. This process emits more photons, which enhance the heat input to the weld materials. The synergy effect is quantified by spectral intensity. It increases with the laser power, and decreases with the arc current and laser-arc distance. It is proportional to the cross section of weld, especially the upper, and beneficial to improve the welding energy utilization. Secondly, the amount of spatter in laser-arc hybrid welding is significantly less than that of arc welding. The bigger weld pool, the downward melt flow, and the reduced droplet transfer force generated by the synergy effect make the transferring droplets more easily absorbed by the weld pool, which stabilizes the transfer process and reduces the generation of spatter. The research results are beneficial for understanding hybrid welding mechanism and optimizing the welding process.

Journal ArticleDOI
18 Jan 2019
TL;DR: In this article, the most representative investigation regarding the use of this technology to join large thickness flat panels of naval steel is presented. And the industrial need of performing one single pass procedure to assure high quality welds of high thickness is suggested as one of the key aspects for future investigations.
Abstract: Plates joining is one of the first stage at large vessels manufacturing line, process conditioning the whole shipbuilding production. Laser Arc Hybrid Welding (LAHW) process is nowadays providing promising results for large thickness naval steel, being primarily used for welding plates with thicknesses between 6 to 15 mm, reaching up to 51 mm. In addition to this high penetration ability, LAHW allows increasing the production rates. Therefore, this technology is proposed as an alternative to conventional welding processes in shipbuilding, as it integrates the advantages of laser and arc welding, providing high process stability, high welding speed and penetration, narrow weld beads with a low heat input and good metallurgical properties. The present review reports the most representative investigation regarding the use of this technology to join large thickness flat panels of naval steel. It includes a summary of the most influential process variables, equipment characteristics, material properties, naval regulations, as well as microstructural characterisation and mechanical properties of joints. This review is thought to help readers from different backgrounds, covering from non-expert on welding or on naval sector, to industrial LAHW applicators and researchers. The industrial need of performing one single pass procedure to assure high quality welds of high thickness is suggested as one of the key aspects for future investigations.

Journal ArticleDOI
TL;DR: In this paper, a modified arc welding process is proposed to establish a cross arc process where two wires are charged by a second power supply and are fed into the main arc (gas tungsten arc (GTA) or plasma arc (PA)) which heats the workpiece.

Journal ArticleDOI
TL;DR: A universal and applicable method to predict bonding quality in narrow-gap laser beam filler wire welding of D406A ultra-high strength steel was presented in this paper, where defect-free joint could be achieved under the predicted optimal welding condition.

Journal ArticleDOI
TL;DR: In this paper, a filler wire was added into the molten pool during the deposition process to regulate the chemical composition of the deposited metal, and intermediate layers, with controlled chemical compositions, were inserted between the materials boundary.
Abstract: Wire and arc-based additive manufacturing (AM) is an additive manufacturing technique applying arc welding technology, where the metal melted by the arc discharge is accumulated and deposited. High-performance products with an excellent mechanical or chemical properties can be obtained using more than two materials through wire and arc-based AM. However, thermal stress and residual stress can form around the interface between two materials. Therefore, the objective of this study is to control the chemical composition of the deposited metal so that it changes gradually near the interface. Intermediate layers, with controlled chemical compositions, were inserted between the materials boundary. To regulate the chemical composition of the deposited metal, a filler wire was added into the molten pool during the deposition process. Results revealed that the chemical composition changed gradually near the interface using the proposed method.

Journal ArticleDOI
TL;DR: In this article, the authors adopted gas tungsten arc welding and pulsed current arc welding technique to suppress the segregation of carbide phases using ERNiCrCoMo-1 filler wire.

Journal ArticleDOI
TL;DR: In this paper, the authors investigated the key technologies for on-line inner porosity detection for aluminum-magnesium (Al-Mg) alloy in pulsed gas tungsten arc welding (GTAW) using arc optical spectroscopy and post-micro-characterization.

Journal ArticleDOI
TL;DR: In this paper, the influence of compound magnetic field on the arc and droplet movement was studied using a pair of high-speed color cameras, and an improved vision-based sensing system was employed to capture 2D image of tracer particle movement on weld pool.

Journal ArticleDOI
TL;DR: In this article, the surface tension mechanism at the interface of melting metal and argon was studied, and the results indicated that pulsed arc pressure created large depressions at the same current level.