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Showing papers on "Electric resistance welding published in 2007"


Journal ArticleDOI
TL;DR: In this paper, a high carbon steel joint was successfully friction stir welded without any pre- or post-heat treatment, and it was proved that friction stir welding enables us to properly control the cooling rate and peak temperature, which was impossible using traditional welding.

252 citations


Journal ArticleDOI
TL;DR: In this article, the effects of various welding parameters on welding penetration in Erdemir 6842 steel having 2.5mm thickness welded by robotic gas metal arc welding were investigated.

182 citations


Journal ArticleDOI
TL;DR: In this article, the influence of pulsed current TIG welding parameters on tensile properties of AA 6061 aluminium alloy weldments was investigated. And the results showed that pulsed currents can improve the mechanical properties of the welds compared to those of continuous current welds.

165 citations


Journal ArticleDOI
TL;DR: In this article, a simple numerical model for predicting the heat generation in friction stir welding (FSW) from the material hot deformation and thermal properties, the process parameters, and the tool and plate dimensions is presented.
Abstract: This paper describes a simple numerical model for predicting the heat generation in friction stir welding (FSW) from the material hot deformation and thermal properties, the process parameters, and the tool and plate dimensions. The model idealises the deformation zone as a two-dimensional axisymmetric problem, but allowance is made for the effect of translation by averaging the three-dimensional temperature distribution around the tool in the real weld. The model successfully predicts the weld temperature field and has been applied with minimal recalibration to aerospace aluminium alloys 2024, 7449 and 6013, which span a wide range of strength. The conditions under the tool are presented as novel maps of flow stress against temperature and strain rate, giving insight into the relationship between material properties and optimum welding conditions. This highlights the need in FSW for experimental high strain rate tests close to the solidus temperature. The model is used to illustrate the optimisat...

150 citations


Journal ArticleDOI
TL;DR: In this article, the effects of laser power, power density and welding speed on the formation of sound welds were investigated with four laser beams of 130, 200, 360 and 560 mm in spot diameter, and their welding phenomena were clarified with high speed video cameras and an x-ray transmission real-time imaging system.
Abstract: The fibre laser has been receiving great attention due to its advantages of high efficiency, high power and high beam quality, and is expected to be one of the most desirable heat sources for high-speed and deep-penetration welding. In this study, therefore, in bead-on-plate welding of Type 304 stainless steel plates with 6 kW fibre laser, the effects of laser power, power density and welding speed on the formation of sound welds were investigated with four laser beams of 130, 200, 360 and 560 µm in spot diameter, and their welding phenomena were clarified with high-speed video cameras and an x-ray transmission real-time imaging system. The weld beads showed a keyhole type of penetration at any diameter, and the maximum penetration of 11 mm in depth was obtained at 130 µm spot diameter and 0.6 m min−1 welding speed. It was found that the laser power density exerted a remarkable effect on the increase in weld penetration at higher welding speeds, and sound partially penetrated welds without welding defects such as porosity, underfilling or humping could be produced at wide process windows of welding speeds between 4.5 and 10 m min−1 with fibre laser beams of 360 µm or 560 µm in spot diameter. The high-speed video observation pictures and the x-ray images of the welding phenomena at 6 m min−1 welding speed and 360 µm spot diameter show that a sound weld bead was formed owing to a long molten pool suppressing and accommodating spattering and a stable keyhole generating no bubbles from the tip, respectively.

147 citations


Journal ArticleDOI
TL;DR: In this article, a two-pass double side welding technique was developed, and a joint thickness of 21mm was decided so that a partial penetration weld can be attempted with lesser beam power.

134 citations


Journal ArticleDOI
TL;DR: In this article, a comparative study of RSW and FSSW on spot welding AHSS has been conducted and the results show a correlation found among microstructure, failure loads, energy requirements and bonded area for both spot welding processes.
Abstract: Efforts to reduce vehicle weight and improve crash performance have resulted in increased application of advanced high strength steels (AHSS) and a recent focus on the weldability of these alloys. Resistance spot welding (RSW) is the primary sheet metal welding process in the manufacture of automotive assemblies. Friction stir spot welding (FSSW) was invented as a novel method to spot welding sheet metal and has proven to be a potential candidate for spot welding AHSS. A comparative study of RSW and FSSW on spot welding AHSS has been completed. The objective of this work is to compare the microstructure and mechanical properties of Zn coated DP600 AHSS (1 . 2 mm thick) spot welds conducted using both processes. This was accomplished by examining the metallurgical cross-sections and local hardnesses of various spot weld regions. High speed data acquisition was also used to monitor process parameters and attain energy outputs for each process. Results show a correlation found among microstructure, failure loads, energy requirements and bonded area for both spot welding processes.

133 citations


Journal ArticleDOI
TL;DR: In this paper, the stability condition of a hybrid laser CO 2 -GMAW welding process was investigated by analyzing the influence of several process parameters, such as the filler metal transfer mode on the stability of the whole process.

102 citations


Journal ArticleDOI
TL;DR: In this article, the minimum net energy input for proper operative and metallurgical weldabilities is studied using two different welding modes: the melt-in or conduction mode and the keyhole mode.

98 citations


Journal ArticleDOI
TL;DR: In this paper, a commercial pure (CP) titanium sheets (ASTM Grade 2) were welded by resistance spot welding at different welding parameters and under different welding environments, and the welded joints were subjected to tensile-shearing tests in order to determine the strength of welded zones.

98 citations


Journal ArticleDOI
TL;DR: In this paper, the development of mathematical equations using a three factor 5-level factorial technique to predict the geometry of weld bead in butt joint of austenitic stainless steel 304 sheet of 2.5 mm thickness is presented.
Abstract: Laser beam welding (LBW) is a field of growing importance in industry with respect to traditional welding methodologies due to lower dimension and shape distortion of components and greater processing velocity. Because of its high weld strength to weld size ratio, reliability and minimal heat affected zone, laser welding has become important for varied industrial applications. With increased use of laser welding in continuous mode, there will be increased dependence on the use of equations to predict the dimensions of the weld bead. In this paper, the development of mathematical equations using a three factor 5- level factorial technique to predict the geometry of weld bead in butt joint of austenitic stainless steel 304 sheet of 2.5 mm thickness are presented. The models developed have been checked for their significance by using F-test and t-test. The direct and interaction effect of the process variables on bead geometry are presented in graphical form for quick analysis.

Journal ArticleDOI
Salim Aslanlar1, A. Ogur1, Ugur Ozsarac1, Erdinç Ilhan1, Z. Demir1 
TL;DR: In this article, the effect of welding current on the quality of weld joint and obviously on tensile shear and tensile-peel strengths of galvanized chromate steel sheets having 1.2mm thickness in electrical resistance spot welding was investigated.

Journal ArticleDOI
TL;DR: In this article, the applicability of friction stir welding on polypropylene sheets has been studied and the joint strength has been analyzed in terms of rotation and translation speed, and it has been demonstrated that in addition to the judicious selection of welding parameters the proper construction of the welding tool is also very important.
Abstract: The applicability of friction stir welding has been studied on polypropylene sheets. The joint strength has been analysed in terms of rotation and translation speed. It has been demonstrated that in addition to the judicious selection of welding parameters the proper construction of the welding tool is also very important. The crystallinity of the seam and its neighbourhood has been analysed by DSC, the structure of the seam border region has been analysed by optical and by scanning electron microscopy. It was found, that the seam has undergone embrittlement, as a result of non-satisfactory homogenization. Having analysed the flow circumstances during welding on seams produced by proper tool geometries it has been demonstrated that homogenization and, consequently the joint strength can be substantially improved.

Journal ArticleDOI
TL;DR: In this article, the authors have attempted to model the temperature distribution for various joint designs of thermoplastics as practised by industry and simulation is done in ANSYS.

Journal ArticleDOI
TL;DR: In this article, a new method to eliminate the interfering radiation during laser-TIG hybrid welding of magnesium alloys and to obtain the distribution of temperature field accurately was proposed, and the results showed that the interferences caused by radiant specular reflection of arc light, ceramic nozzle, electrode and laser nozzle were transferred out of welding seam while the IR thermography system was placed perpendicularly to welding seam.
Abstract: Infrared (IR) temperature measurement, as a convenient, non-contact method for making temperature field measurements, has been widely used in the fields of welding, but the problem of interference from radiant reflection is a complicating factor in applying IR temperature sensing to welding. The object of this research is to make a deep understand about the formation of interference, explore a new method to eliminate the interfering radiation during laser-TIG hybrid welding of magnesium alloys and to obtain the distribution of temperature field accurately. The experimental results showed that the interferences caused by radiant specular reflection of arc light, ceramic nozzle, electrode and laser nozzle were transferred out of welding seam while the IR thermography system was placed perpendicularly to welding seam. And the welding temperature distribution captured by IR termography system which had been calibrated by thermocouple was reliable by using this method in hybrid laser-TIG welding process of AZ31B magnesium alloy.

Journal ArticleDOI
TL;DR: In this article, the effect of pulsed current and post weld aging treatment on tensile properties of argon arc welded AA7075 aluminium alloy has been revealed, where four different welding techniques have been used to fabricate the joints and they are: (i) continuous current GTAW (CCGTAW), (ii) pulsed currents GTAW, (iii) continuous currents GMAW (CGMAW), and (iv) pulses current GMAWS (PCGMAWS) processes.
Abstract: This paper reveals the effect of pulsed current and post weld aging treatment on tensile properties of argon arc welded AA7075 aluminium alloy. This alloy has gathered wide acceptance in the fabrication of light weight structures requiring high strength-to-weight ratio, such as transportable bridge girders, military vehicles, road tankers and railway transport systems. The preferred welding processes of high strength aluminium alloy are frequently gas tungsten arc welding (GTAW) process and gas metal arc welding (GMAW) process due to their comparatively easier applicability and better economy. Weld fusion zones typically exhibit coarse columnar grains because of the prevailing thermal conditions during weld metal solidification. This often results inferior weld mechanical properties and poor resistance to hot cracking. In this investigation, an attempt has been made to refine the fusion zone grains by applying pulsed current welding technique. Four different welding techniques have been used to fabricate the joints and they are: (i) continuous current GTAW (CCGTAW), (ii) pulsed current GTAW (PCGTAW), (iii) continuous current GMAW (CCGMAW) and (iv) pulsed current GMAW (PCGMAW) processes. As welded joint strength is much lower than the base metal strength and hence, a simple aging treatment has been given to improve the tensile strength of the joints. Current pulsing leads to relatively finer and more equi-axed grain structure in GTA and GMA welds. In contrast, conventional continuous current welding resulted in predominantly columnar grain structures. Post weld aging treatment is accompanied by an increase in tensile strength and tensile ductility.

Journal ArticleDOI
TL;DR: In this article, the authors investigated the potential of mechanical tensioning to reduce the magnitude of residual stresses in welds and to eliminate buckling distortion in both friction stir (FSW) and arc welds.
Abstract: This paper investigates the potential of mechanical tensioning (MT) to reduce the magnitude of residual stresses in welds and to eliminate buckling distortion. Both friction stir (FSW) and arc welds have been produced from the aluminium alloy AA2024, with different levels of tensile stress applied along the weld line either during or after welding. The resulting welds have been characterised in terms of out of plane distortion, residual stresses and microstructure. Buckling distortion was eliminated by stretching plates to between 35 and 70% of the yield stress of the material during welding. For each set of welding parameters investigated, an optimum tensioning stress has been identified, which eliminates the tensile residual stress peak across the weld zone, along with distortion. This optimum tensioning stress increases in line with the heat input of the welding process. When MT stresses are increased beyond this optimum value, then distortion arises once more and a band of compressive stress i...

Journal ArticleDOI
TL;DR: In this article, a three-dimensional numerical heat transfer and fluid flow model is developed to capture the effects of the tilt angle of the fillet joint and the welding positions, i.e., V, L, and other configurations on the temperature profiles, velocity fields, welding pool shape, weld pool free surface profile, thermal cycles, and cooling rates during GMA welding in spray mode.
Abstract: Gas-metal-arc (GMA) fillet welding is one of the most commonly used welding processes in the industry. This welding process is characterized by the complex joint geometry, a deformable weld pool surface, and the addition of hot metal droplets. In this work, a three-dimensional numerical heat-transfer and fluid-flow model is developed to capture the effects of the tilt angle of the fillet joint and the welding positions, i.e., V, L, and other configurations on the temperature profiles, velocity fields, weld pool shape, weld pool free surface profile, thermal cycles, and cooling rates during GMA welding in spray mode. The governing equations of conservation of mass, momentum, and energy are solved using a boundary fitted curvilinear coordinate system. The weld pool free surface deformation is calculated by minimizing the total surface energy. A dimensional analysis is performed to understand the importance of heat transfer by conduction and convection and the role of various driving forces on convection in the liquid weld pool. The computed shape and size of the fusion zone, finger penetration characteristic of the GMA welds, and the solidified free surface profile are in fair agreement with the corresponding experimental results. The calculated cooling rates are also in good agreement with independent experimental data. The results reported here indicate a significant promise for understanding the effect of joint orientations and welding positions on weld pool shape, size, and the cooling rates based on fundamental principles of transport phenomena.

Journal ArticleDOI
TL;DR: In this paper, a wide study on the hybrid CO2 LASER-MIG welding and investigates the influence of the shielding gas both on the stability of the process and on the dimensional characteristics of the weld bead.

Journal ArticleDOI
TL;DR: In this paper, genetic algorithm-based computational models have been developed to determine the optimum/near optimum process parameters to achieve the target weld-bead geometry in 304LN and 316LN stainless steel welds produced by A-TIG welding.
Abstract: The weld-bead geometry in 304LN and 316LN stainless steels produced by A-TIG welding plays an important role in determining the mechanical properties of the weld and its quality. Its shape parameters such as bead width, depth of penetration, and reinforcement height are decided according to the A-TIG welding process parameters such as current, voltage, torch speed, and arc gap. Identification of a suitable combination of A-TIG process parameters to produce the desired weld-bead geometry required many experiments, and the experimental optimization of the A-TIG process was indeed time consuming and costly. Therefore it becomes necessary to develop a methodology for optimizing the A-TIG process parameters to achieve the target weld-bead geometry. In the present work, genetic algorithm (GA)-based computational models have been developed to determine the optimum/near optimum process parameters to achieve the target weld-bead geometry in 304LN and 316LN stainless steel welds produced by A-TIG welding.

Journal ArticleDOI
TL;DR: In this paper, an experimental investigation of resistance welding of APC-2/AS4 PEEK/carbon fiber composite using a stainless steel mesh heating element is presented, where a special specimen geometry, the skin/stringer configuration, was used to represent a typical reinforced aerospace structural joint.
Abstract: An experimental investigation of resistance welding of APC-2/AS4 PEEK/carbon fibre composite using a stainless steel mesh heating element is presented. A special specimen geometry, the skin/stringer configuration, was used to represent a typical reinforced aerospace structural joint. The specimens consisted of a flange, representing a stringer or frame, welded onto a skin laminate. The effects of the welding parameters such as the input power level and clamping distance on the weld quality and performance were investigated. The welding parameters were optimised using short beam shear tests, ultrasonic C-scan inspection and optical microscopy. The mechanical performance of the resistance-welded skin/stringer configuration was investigated using three- and four-point bending tests and the failure mechanisms were characterised by optical and scanning electron microscopy. Two methods were used to reduce the stress concentration at the flange tip. The first method was to machine a 20° taper angle at the edge of the flange and the second one was to create a resin fillet at the flange tip. No mechanical performance improvement was obtained with the resin fillet method but the taper angle method showed 25% mechanical performance improvement when the taper angles were machined after the welding operation.

Journal ArticleDOI
TL;DR: In this article, the influence of the primary welding parameters affecting the heat input such as; peak current on the morphology, microhardness, and tensile shear load bearing capacity of dissimilar welds between AISI 316L austenitic stainless steel and DIN EN 10130-99 (7114 grade) interstitial free steel has been investigated.

Journal ArticleDOI
TL;DR: In this article, an experimental study on the laser welding of MMCs using both a CO 2 and a diode laser source is presented, where the CO 2 welding is performed in keyhole conditions (deep penetration), whereas the diode source performs conduction welding.
Abstract: Metal matrix composites are well known materials that present several positive features, mainly in terms of mechanical strength to weight ratio. On the other side, MMC's are extremely difficult to machine (in particular by chip removal processes) and this difficulty has limited a wider diffusion. Welding, together with other joining technologies, could be a solution to limit the chip removal processes in the production of a MMC part, but this is not a problem-free process. This paper presents an experimental study on the laser welding of MMCs using both a CO 2 and a diode laser source. The CO 2 welding is performed in keyhole conditions (deep penetration), whereas the diode laser performs a conduction welding. Results show that the CO 2 welding is greatly affected by the formation of Al 4 C 3 , that compromises the toughness of the bead. The content of Al 4 C 3 can be reduced by acting on the process parameters, but cannot be completely eliminated. Instead, diode laser welding generates a sound bead, with negligible Al 4 C 3 formation and of superior quality. Considering also the other positive features of this kind of sources (high efficiency and radiation wavelength, that is, highly absorbed by MMCs), diode laser welding seems to be highly recommendable for MMCs laser welding.

Journal ArticleDOI
TL;DR: In this article, the performance of the extruded profile in subsequent manufacturing processes such as bending or forming is limited by the strength of the weakest weld, and the results were compared with unwelded profiles.

Patent
21 Feb 2007
TL;DR: In this article, a joint product between a steel product and an aluminum material, which can realize spot welding with high bonding strength, and a spot welding method for the joint product was provided.
Abstract: This invention provides a joint product between a steel product and an aluminum material, which can realize spot welding with high bonding strength, and a spot welding method for the joint product. In one embodiment, a steel product (1) having a sheet thickness t1 of 0.3 to 3.0 mm is joined to an aluminum material (2) having a sheet thickness t2 of 0.5 to 4.0 mm by spot welding to form a joint product between the steel product and the aluminum material. The joint product is characterized in that the nugget area in the joint is 20 × t20.5 to 100 × t20.5 mm2, the area of a part where the thickness of an interface reaction layer is 0.5 to 3 µm, is not less than 10 × t20.5 mm2, and the difference in thickness of the interface reaction layer between the joint center and a point distant from the joint center by a distance of one-fourth of the joint diameter DC is not more than 5 μm. The above constitution can provide a high-bonding strength joint product, between dissimilar materials, which can be formed without newly using other materials such as clad materials and without newly adding a separate step using an existing spot welding apparatus at low cost, and a spot welding method.

Journal ArticleDOI
TL;DR: In this paper, a hollow axis motor driven high speed rotation arc system for narrow gap welding (NGW) was developed and some welding experiments were carried out to investigate the characteristics of welding wire melting and weld formation for this new process.
Abstract: The present paper develops a hollow axis motor driven high speed rotation arc system for narrow gap welding (NGW), and introduces the features of this system. Some welding experiments were then carried out to investigate the characteristics of welding wire melting and weld formation for this new process. Experimental results show that the melting rate of wire increases and the residual melting ball diameter of wire tip decreases respectively with an increase in rotation speed, and this melting rate is higher in pulsed welding and NGW respectively than in dc and flat plate welding. Furthermore, the arc rotation can obviously improve the penetration into NGW groove sidewalls and bead shape, and thus the system has been used to weld practical NGW joints successfully.

Journal ArticleDOI
TL;DR: In this paper, a new approach for the laser transmission welding developed for the packaging of disposable polymeric microfluidic-biochips is presented, which combines the characteristics of the polymer contour welding and quasi-simultaneous welding and allows the achievement of contamination-free, high quality weld seams as narrow as 100μm with a high dynamic.

Journal ArticleDOI
TL;DR: In this article, a semicoupled thermomechanical finite element model containing both thermal load and mechanical load was established to simulate the development of welding stresses during FSW process; an autoadapting heat source model was employed in the thermal analysis; the fixture was also included in the mechanical analysis model.
Abstract: As a solid state joining technique, friction stir welding (FSW) can produce high strength, low distortion joints efficiently. Compared to fusion welding, residual stresses in FSW joints are expected to be low due to a relatively low heat input. However, apart from the heat input, the force from the tool also plays an important role in the development of welding stresses. In the present paper, a semicoupled thermomechanical finite element model containing both thermal load and mechanical load was established to simulate the development of welding stresses during FSW process; an autoadapting heat source model was employed in the thermal analysis; the fixture was also included in the mechanical analysis model. The simulation results showed that due to the effect of the tool force, the longitudinal residual tensile stresses became smaller and were asymmetrically distributed at different sides of the weld centre; the peak of the tensile residual stresses at the retreating side was lower than that at th...

Patent
18 Dec 2007
TL;DR: In this paper, an aluminum alloy brazing sheet for heat exchangers has a core, a sacrificial material formed on one side of the core, and a filler metal formed on the other side of core.
Abstract: An aluminum alloy brazing sheet for heat exchangers has a core, a sacrificial material formed on one side of the core, and a brazing filler metal formed on the other side of core. The core is made of an aluminum alloy containing predetermined amounts of Si, Cu, and Mn, the balance being Al and unavoidable impurities. The sacrificial material is made of an aluminum alloy containing predetermined amounts of Si, Zn, and Mg with the balance of Al and unavoidable impurities. The brazing filler metal is made of an aluminum alloy. The aluminum alloy brazing sheet for heat exchangers has a work hardening exponent n of not less than 0.05. The aluminum alloy brazing sheet for heat exchangers has excellent strength and corrosion resistance even when it is formed into a thin material and also has excellent high frequency weldability and weld cracking resistance during electric resistance welding (high frequency welding properties).

Journal ArticleDOI
TL;DR: In this paper, different welding techniques were used to evaluate the mechanical performance of weldments of HY-80 steel, and the effects of welding methods on weld metal microstructure and mechanical properties including weld metal tensile strength and Charpy V-notch impact toughness over the temperature range −20 to 20°C were investigated.