Showing papers on "Gas metal arc welding published in 2009"
TL;DR: In this article, the effect of welding processes such as GTAW, GMAW, and FSW on mechanical properties of AA6061 aluminium alloy was investigated, and it was found that FSW joints of AA 6061 aluminum alloy showed superior mechanical properties compared with GTAW and GMAw joints, and this was mainly due to the formation of very fine, equiaxed microstructure in the weld zone.
Abstract: The present investigation is aimed at to study the effect of welding processes such as GTAW, GMAW and FSW on mechanical properties of AA6061 aluminium alloy. The preferred welding processes of these alloys are frequently gas tungsten arc welding (GTAW) and gas metal arc welding (GMAW) due to their comparatively easier applicability and better economy. In this alloy, the weld fusion zones typically exhibit coarse columnar grains because of the prevailing thermal conditions during weld metal solidification. This often causes inferior weld mechanical properties and poor resistance to hot cracking. Friction stir welding (FSW) is a solid phase welding technique developed primarily for welding metals and alloys that heretofore had been difficult to weld using more traditional fusion techniques. Rolled plates of 6 mm thickness have been used as the base material for preparing single pass butt welded joints. The filler metal used for joining the plates is AA4043 (Al-5Si (wt%)) grade aluminium alloy. In the present work, tensile properties, micro hardness, microstructure and fracture surface morphology of the GMAW, GTAW and FSW joints have been evaluated, and the results are compared. From this investigation, it is found that FSW joints of AA6061 aluminium alloy showed superior mechanical properties compared with GTAW and GMAW joints, and this is mainly due to the formation of very fine, equiaxed microstructure in the weld zone.
271 citations
TL;DR: In this article, the wave control characteristics and its droplet transfer process were analyzed by sensing and image method, and the results show that it can realize no-spatter welding and low heat input during welding process.
197 citations
15 Jan 2009-Materials Science and Engineering A-structural Materials Properties Microstructure and Processing
TL;DR: In this article, a modified metal inert gas welding process based on short-circuiting the transfer process, characterised by low heat input and no-spatter welding, was used to join aluminium to zinc-coated steel.
Abstract: Cold metal transfer (CMT) is a modified metal inert gas welding process based on short-circuiting the transfer process, characterised by low heat input and no-spatter welding. The arc characteristics and its droplet transfer process have been studied by high-speed video photography. The process was used to join aluminium to zinc-coated steel. The results shows that no-spatter welding and low heat input during the welding process can be realized by CMT, and a dissimilar metal joint with good performance can be obtained by the CMT process.
192 citations
TL;DR: In this article, the influence of thermophysical properties on the parameters of tungsten-inert-gas (TIG) welding arcs, particularly those that affect the weld pool, is investigated using a two-dimensional model in which the arc, anode and cathode are included self-consistently.
Abstract: The methods used to model thermal plasmas, including treatments of diffusion in arcs in gas mixtures, are reviewed. The influence of thermophysical properties on the parameters of tungsten–inert-gas (TIG) welding arcs, particularly those that affect the weld pool, is investigated using a two-dimensional model in which the arc, anode and cathode are included self-consistently. The effect of changing each of six thermophysical properties on the characteristics of an argon TIG arc is assessed. The influence of the product of specific heat and mass density is found to be particularly important in determining the arc constriction. By examining the influence of the different properties on the heat flux density, current density and shear stress at the anode, it is concluded that the weld pool depth can be increased by using shielding gases with high specific heat, thermal conductivity and viscosity. The effect of metal vapour on the arc and weld pool properties is assessed. The most important effect of the metal vapour is found to be the increased electrical conductivity at low temperatures, which leads to lower heat flux density and current density at the weld pool, implying a shallower weld pool.
160 citations
TL;DR: In this paper, the penetration depth reached 18 mm at the maximum at 5 mm s−1, and porosity was generated at any fibre laser spot diameter at any fiber laser beam diameter.
Abstract: The objectives of this research are to investigate penetration characteristics, to clarify welding phenomena and to develop high quality welding procedures in bead on plate welding of type 304 austenitic stainless steel plates with a 10 kW fibre laser beam. The penetration depth reached 18 mm at the maximum at 5 mm s−1. At 50 mm s−1 or lower welding speeds, however, porosity was generated at any fibre laser spot diameter. On the other hand, at 100 mm s−1 or higher welding speeds, underfilling and humping weld beads were formed under the conventionally and tightly focused conditions respectively. The generation of spatters was influenced mainly by a strong shear force of a laser induced plume and was greatly reduced by controlling direction of the plume blowing out of a keyhole inlet. The humping formation was dependent upon several dynamic or static factors, such as melt volume above the surface, strong melt flow to the rear molten pool on the top surface, solidification rate and narrow molten poo...
156 citations
TL;DR: In this paper, the relation between energy density and welding pressure in welding certain types of aluminum alloys was clarified, and the welding energy is effectively used in the ultrasonic welding of a flexible, narrow material with a narrow pressurization area.
122 citations
TL;DR: In this article, the influence of adding helium, hydrogen and nitrogen to the argon shielding gas is investigated and it is found that adding any of the gases increases the heat flow to and the current density at the anode.
Abstract: Tungsten?inert-gas welding arcs are modelled using a two-dimensional axisymmetric computational code. Both electrodes (the tungsten cathode and the metal anode workpiece) and the arc plasma are included self-consistently in the computational domain. The influence of adding helium, hydrogen and nitrogen to the argon shielding gas is investigated. It is found that addition of any of the gases increases the heat flow to and the current density at the anode. The shear stress and the arc pressure at the anode surface are increased by adding hydrogen or nitrogen or up to about 50?mol% helium, but decrease when more helium is added. It is predicted that the effect of adding any of the gases is to increase the depth of the weld pool, in agreement with the experimental evidence. The results are explained by referring to the thermodynamic and transport properties of the gas mixtures.
114 citations
TL;DR: An integrated comprehensive 3D model has been developed to study the transport phenomena in gas metal arc welding (GMAW), including the arc plasma, droplet generation, transfer and impingement onto the weld pool, and weld pool dynamics as discussed by the authors.
106 citations
TL;DR: In this paper, the authors compare welds made by submerged arc welding (SAW) with DC gas metal arc welding, pulsed gas metal arcs welding, Fronius cold metal transfer (CMT), autogenous laser and laser hybrid welding on butt welds in 4 mm thick DH36 ship plate.
Abstract: Residual stress and distortion continue to be important issues in shipbuilding and are still subject to large amounts of research. This paper demonstrates how the type of welding process influences the amount of distortion. Many shipyards currently use submerged arc welding (SAW) as their welding process of choice. In this manuscript, the authors compare welds made by SAW with DC gas metal arc welding, pulsed gas metal arc welding, Fronius cold metal transfer (CMT), autogenous laser and laser hybrid welding on butt welds in 4 mm thick DH36 ship plate. Laser and laser hybrid welding were found to produce the lowest distortion. Nevertheless, a considerable improvement can be achieved with the pulsed gas metal arc welding and CMT processes. The paper seeks to understand the relationship between heat input, fusion area, measured distortion and the residual stress predicted from a simple numerical model, and the residual stresses validated with experimental data.
103 citations
TL;DR: In this article, the effect of welding parameters on the hybrid weldability was investigated concerning the bead shape, hardness, tensile properties and microstructures of welded joints compared with those of a fiber laser welded joint.
94 citations
TL;DR: In this article, the process characteristics of active flux tungsten inert gas welding and keyhole mode GTAW, two recent developments to GTAW are considered, as is keyholemode plasma arc welding, which is capable of greater penetration and faster processing speeds than conventional GTAW.
Abstract: Titanium alloys used in aerospace structures require joints of high integrity to meet the design requirements. Gas tungsten arc welding (GTAW), laser beam welding (LBW) and electron beam welding (EBW) are all processes capable of creating fusion welded joints. Gas tungsten arc welding offers the potential to achieve welds of equal quality to EBW or LBW at much lower capital costs; however, the application of GTAW involves gaining an understanding of the complex process characteristics. This paper reviews the process characteristics for GTAW titanium alloys and compares these characteristics with EBW and LBW titanium alloys. The characteristics of active flux tungsten inert gas welding and keyhole mode GTAW, two recent developments to GTAW, are considered, as is keyhole mode plasma arc welding. These variants are capable of greater penetration and, in some cases, faster processing speeds than conventional GTAW. Finally, the current knowledge of weld microstructural development in cast and wrought α...
TL;DR: In this article, a U-TIG-assisted tungsten inert gas welding method was developed for AISI 304 stainless steel with 5 mm thickness and the results show that the penetration depth is increased up to 300% for weld made with U-tIG welding compared with conventional TIG welding.
Abstract: Ultrasonic assisted tungsten inert gas (U-TIG) welding method was developed. Both U-TIG and conventional TIG welding of AISI 304 stainless steel with 5 mm thickness were experimentally studied in this paper. The results show that the penetration depth is increased up to 300% for weld made with U-TIG welding compared with conventional TIG welding. Ultrasonic energy enhances arc push force, causes a continual high frequency oscillation in the arc plasma and increases welding penetration. These effects are thought to be responsible for enhancing the welding efficiency and improving the appearance of stainless steel weld joints.
TL;DR: In this paper, the effects of laser power, welding speed, focal position, shielding gas and zinc vaporization on welding quality of high-strength galvanized steel sheets are investigated.
TL;DR: In this article, an electromagnetic impact welding (EIFW) technique was used to lap weld Mg and Al alloys using an X-ray diffraction analysis and showed no intermetallic phases and suggested that this electromagnetic technique is a solid state welding process.
Abstract: Magnesium (Mg) and aluminium (Al) alloys have been lap welded using an electromagnetic impact welding technique. Metallographic examination of the welds has revealed sound and defect free interfaces. Complete metal continuity has been observed with a characteristic wavy interface. X-ray diffraction analysis has shown no intermetallic phases and suggested that this electromagnetic technique is a solid state welding process. All the shear strength samples welded with discharge energy of 6·7 kJ failed away from weld either in the plastically deformed zone or in the base metal. Optimum discharge energy has been determined as 6·7 kJ based on the shear strength results of the welds.
TL;DR: In this paper, mathematical models that correlate welding process parameters to weld bead geometry are developed with experimental investigation, and five process parameters, viz., wire feed rate, plate thickness, pulse frequency, pulse current magnitude, and travel speed, are selected to develop the models using multiple regression analysis.
Abstract: Pulsed gas metal arc welding is one of the most widely used processes in the industry. It offers spray metal transfer at low average currents, high metal deposition rate, versatility, less distortion, and the ability to be used in automated robotic welding systems. The weld bead plays an important role in determining the mechanical properties of the weld. Its geometric parameters, viz., width, reinforcement height, and penetration, are decided according to the welding process parameters, such as wire feed rate, welding speed, pulse current magnitude, frequency (cycle time), etc. Therefore, to produce good weld bead geometry, it is important to set the proper welding process parameters. In the present paper, mathematical models that correlate welding process parameters to weld bead geometry are developed with experimental investigation. Taguchi methods are applied to plan the experiments. Five process parameters, viz., wire feed rate, plate thickness, pulse frequency, pulse current magnitude, and travel speed, are selected to develop the models using multiple regression analysis. The models developed were checked for their adequacy. Results of confirmation experiments show that the models can predict the bead geometry with reasonable accuracy.
TL;DR: In this paper, an investigation on microstructure, weld bead geometry, dilution and mechanical properties of butt and overlap weld joints of thin aluminium sheets 1 mm of 6082 Al alloy produced by using AC P-GMA welding was carried out.
TL;DR: In this article, the effect of pulse parameters has been studied by considering their hypothetically proposed summarized influence defined by a dimensionless factor ϕ ǫ = [( I b / I p ) ft b ], mean current and arc voltage and correlation between welding parameters and arc characteristics have been established.
TL;DR: In this paper, the authors evaluated the feasibility of laser welding structural transition joints to overcome manufacturing limitations of traditional TIG/MIG welding by imposing severe thermal cycles on the material.
TL;DR: In this article, the effect of welding parameters on the distribution of wire feeding elements has been investigated during CO2 laser and pulsed gas metal arc hybrid welding process, and the results indicate that the fluid flow towards the inside of keyhole, namely inward flow, improves the homogeneity of weld metal.
Abstract: The effect of welding parameters on the distribution of wire feeding elements has been investigated during CO2 laser and pulsed gas metal arc hybrid welding process. The molten metal flow on the pool surface and inside of the samples was observed by a high speed video camera and an in situ X-ray transmission imaging system respectively. The results indicate that the fluid flow towards the inside of keyhole, namely inward flow, improves the homogeneity of weld metal. The distribution of alloying elements is more homogeneous in leading laser compared with leading arc, since both of the drag force of the plasma jet and momentum of droplet promote the inward flow in leading laser. Almost homogeneous distribution of alloying elements can be attained if the oxygen content in the shielding gas is more than 2%, since the Marangoni flow direction changes from outward to inward with increasing the oxygen content.
TL;DR: In this article, an attempt has been made to determine the best welding process to hardface boiler grade steels based on quantitative factors (by measuring percentage of dilution) and qualitative factors (using the analytic hierarchy process [AHP]).
Abstract: Weld hardfacing techniques are employed mainly to extend or improve the service life of engineering components either by rebuilding or by fabricating in such a way as to produce a composite wall section to combat wear, erosion, corrosion, etc. In this paper, an attempt has been made to determine the best welding process to hardface boiler grade steels based on quantitative factors (by measuring percentage of dilution) and qualitative factors (using the analytic hierarchy process [AHP]). Five different welding processes including shielded metal arc welding (SMAW), gas metal arc welding (GMAW), gas tungsten arc welding (GTAW), submerged arc welding (SAW), and plasma transferred arc welding (PTAW) have been compared. Based on the quantitative and qualitative factors, the PTAW process is found to be the best method to hardface boiler grade steels.
TL;DR: In this article, a mathematical model was established to simulate the weld pool development and dynamic process in stationary laser-metal inert gas (MIG) hybrid welding, where surface tension and buoyancy were considered to calculate liquid metal flow pattern.
Abstract: A mathematical model was established to simulate the weld pool development and dynamic process in stationary laser–metal inert gas (MIG) hybrid welding. Surface tension and buoyancy were considered to calculate liquid metal flow pattern; moreover, typical phenomena of MIG welding such as filler droplets impinging weld pool, electromagnetic force in the weld pool, and typical phenomena of laser beam welding such as recoil pressure, inverse Bremsstrahlung absorption, and Fresnel absorption were all considered in the model. The laser beam and arc couple effect was introduced into this model by the plasma width during hybrid welding. Transient weld pool shape and complicated liquid metal velocity distribution from two kinds of weld pool to a unified weld pool were calculated. Furthermore, the simulated weld bead geometries were in good agreement with experimental measurement.
TL;DR: In this paper, a rapid solidification of amorphous and metallic glass thin foils was attempted by employing underwater shock wave assembly. And the conditions of the explosive welding were numerically analyzed and discussed based on the earlier welding limits.
TL;DR: In this paper, the effects of various welding conditions on penetration and defect formation were investigated, and the authors clarified their welding phenomena and developed the procedure of defect formation in order to develop the defect formation procedure.
Abstract: The objectives of this research are to investigate the effects of various welding conditions on penetration and defect formation, to clarify their welding phenomena and to develop the procedure of ...
TL;DR: In this article, the effect of welding processes such as shielded metal arc welding, gas metal arc and gas tungsten arc welding on tensile and impact properties of the ferritic stainless steel conforming to AISI 409M grade is studied.
Abstract: The effect of welding processes such as shielded metal arc welding, gas metal arc welding and gas tungsten arc welding on tensile and impact properties of the ferritic stainless steel conforming to AISI 409M grade is studied. Rolled plates of 4 mm thickness were used as the base material for preparing single pass butt welded joints. Tensile and impact properties, microhardness, microstructure and fracture surface morphology of the welded joints have been evaluated and the results are compared. From this investigation, it is found that gas tungsten arc welded joints of ferritic stainless steel have superior tensile and impact properties compared with shielded metal arc and gas metal arc welded joints and this is mainly due to the presence of finer grains in fusion zone and heat affected zone.
TL;DR: In this article, the effects of wire/flux combination on the chemical composition, tensile strength, and impact toughness of the weld metal were investigated and interpreted in terms of element transfer between the slag and the welding metal, i.e., Δ quantity.
Abstract: Submerged arc welding was performed using metal-cored wires and fluxes with different compositions. The effects of wire/flux combination on the chemical composition, tensile strength, and impact toughness of the weld metal were investigated and interpreted in terms of element transfer between the slag and the weld metal, i.e., Δ quantity. Both carbon and manganese show negative Δ quantity in most combinations, indicating the transfer of the elements from the weld metal to the slag during welding. The amount of transfer, however, is different depending on the flux composition. More basic fluxes yield less negative Δ C and Δ Mn through the reduction of oxygen content in the weld metal and presumably higher Mn activity in the slag, respectively. The transfer of silicon, however, is influenced by Al2O3, TiO2 and ZrO2 contents in the flux. Δ Si becomes less negative and reaches a positive value of 0.044 as the oxides contents increase. This is because Al, Ti, and Zr could replace Si in the SiO2 network, leaving more Si free to transfer from the slag to the weld metal. Accordingly, the Pcm index of weld metals calculated from chemical compositions varies from 0.153 to 0.196 depending on the wire/flux combination, and it almost has a linear relationship with the tensile strength of the weld metal.
TL;DR: In this article, the effect of laser beam on arc plasma was investigated, and the influence of laser power on the welding quality was investigated and it was found that the threshold value for laser power which can improve welding quality is 50-70 W in hybrid welding.
Abstract: The previous work indicated that there were interactions between laser beam and arc plasma in low-power laser/arc hybrid welding. In order to study the interactions, the spectra of plasmas in tungsten inert gas (TIG) welding and hybrid laser/TIG welding of magnesium alloy are acquired, and the differences between them are analyzed. In hybrid welding, the intensities of emission spectra of Mg I and Mg II are much stronger than in TIG welding, while those of Ar I and Ar II are a little weaker than in TIG welding. The temporal characterizations of the sensitive lines of Ar I, Ar II, Mg I, and Mg II are studied to investigate the effect of laser beam on arc plasma. In addition, the influence of laser power on the welding quality is investigated, and it is found that the threshold value of laser power which can improve the welding quality is 50-70 W in hybrid welding. Finally, the electron temperature and electron density of welding plasma are estimated, and the interaction between laser and arc is discussed.
TL;DR: In this article, the influence of variation in the shielding gas composition on the weld properties of the steel ST 37-2 was investigated and it was found that the absorbed energy in the Charpy impact test first increases then remains constant with increase of the amount of carbon dioxide in the shield gas composition.
TL;DR: In this article, a new technology that alternately supplies the different kinds of shielding gases in weld zone has been developed to increase the welding quality and reduce the energy consumption and emission rate of fume.
Journal Article•
TL;DR: In this article, the authors used the Ti-6AI-4V (4.5 g/cm~3 ) to test the performance of GTA-6.5.
TL;DR: In this article, shielded metal arc welding electrodes were produced for making boride coatings and low-carbon steel plates were surfaced with single-pass bead on-plate welds, and the effects of the boron content in the electrode shield on the microstructure and hardness of the coatings were investigated.
Abstract: In the present study, shielded metal arc welding electrodes were produced for making boride coatings and low-carbon steel plates were surfaced with single-pass bead on-plate welds. The effects of the boron content in the electrode shield on the microstructure and hardness of the coatings were investigated. After deposition, microstructural analyses including metallographic examination, wavelength-dispersive X-ray (WDX), X-ray and microhardness measurements of the coatings were evaluated. From the results, it was seen that different boron contents formed primary and eutectic Fe2B, and consequently had an effect on the hardness of the coating. As the amount of boron which was transferred from the electrode shield to the coating increased, the microstructure of the coating changed from the eutectic structure (α-Fe + F2B) to primary Fe2B with the eutectic of Fe2B plus martensite, and the hardness increased. The present study has therefore shown that the shielded metal arc welding electrodes produced here for the first time can be used effectively and economically to produce boride coatings on SAE 1020 steel.