Showing papers on "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: Hybrid welding as mentioned in this paper combines the combination of a laser and an electrical arc to overcome problems commonly encountered during either laser or arc welding such as cracking, brittle phase formation and porosity.
Abstract: Hybrid welding, using the combination of a laser and an electrical arc, is designed to overcome problems commonly encountered during either laser or arc welding such as cracking, brittle phase formation and porosity. When placed in close contact with each other, the two heat sources interact in such a way as to produce a single high intensity energy source. This synergistic interaction of the two heat sources has been shown to alleviate problems commonly encountered in each individual welding process. Hybrid welding allows increased gap tolerances, as compared to laser welding, while retaining the high weld speed and penetration necessary for the efficient welding of thicker workpieces. A number of simultaneously occurring physical processes have been identified as contributing to these unique properties obtained during hybrid welding. However, the physical understanding of these interactions is still evolving. This review critically analyses the recent advances in the fundamental understa...
193 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
Patent•
20 Aug 2009
TL;DR: In this article, a real-time virtual reality welding system including a programmable processor-based subsystem, a spatial tracker operatively connected to the PLC, at least one mock welding tool capable of being spatially tracked by the spatial tracker, and at least a display device operating on the programmable PLC.
Abstract: A real-time virtual reality welding system including a programmable processor- based subsystem, a spatial tracker operatively connected to the programmable processor- based subsystem, at least one mock welding tool capable of being spatially tracked by the spatial tracker, and at least one display device operatively connected to the programmable processor-based subsystem. The system is capable of simulating, in virtual reality space, a weld puddle having real-time molten metal fluidity and heat dissipation characteristics. The system is further capable of displaying the simulated weld puddle on the display device in real-time.
126 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: 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
Book•
01 Jan 2009
TL;DR: In this paper, the authors present a comprehensive numerical simulation of laser materials processing, including keyhole welding, keyhole cutting, and femtosecond laser Pulse Interactions with metals.
Abstract: Mathematics in Laser Processing.- Simulation of Laser Cutting.- Keyhole Welding: The Solid and Liquid Phases.- Laser Keyhole Welding: The Vapour Phase.- Basic Concepts of Laser Drilling.- Arc Welding and Hybrid Laser-Arc Welding.- Metallurgy of Welding and Hardening.- Laser Cladding.- Laser Forming.- Femtosecond Laser Pulse Interactions with Metals.- Comprehensive Numerical Simulation of Laser Materials Processing.
96 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...
93 citations
01 Jan 2009
TL;DR: In this paper, the authors describe the characteristics of hybrid laser-arc welding processes and the properties of joints produced by the hybrid laser arc welding process, as well as the quality control and assessing weld quality.
Abstract: Part 1 Characteristics of hybrid laser-arc welding: Advantages and disadvantages of arc and laser welding Fundamentals of hybrid laser-arc welding Heat sources of hybrid laser-arc welding processes Effect of shielding gas on hybrid laser-arc welding Properties of joints produced by hybrid laser-arc welding Quality control and assessing weld quality in hybrid laser-arc welding. Part 2 Applications of hybrid laser-arc welding: Hybrid welding of magnesium alloys Shipbuilding applications of hybrid laser-arc welding Industrial robotic application of laser-GMAW and laser-Tandem hybrid welding Hybrid laser-arc welding of aluminium Hybrid laser-arc welding of dissimilar metals. Part 3 Hybrid laser-arc welding of steel: Hybrid laser-arc welding of steel.
TL;DR: In this paper, the use of high power lasers for hardfacing (laser cladding) has attracted a great attention in the last decade as an alternative to other more standard methods (arc welding, oxy-fuel gas welding, thermal spraying).
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 paper, the application of response surface methodology was highlighted to predict and optimize the percentage of dilution of iron-based hardfaced surface produced by the PTA (plasma transferred arc welding) process.
Abstract: The application of response surface methodology was highlighted to predict and optimize the percentage of dilution of iron-based hardfaced surface produced by the PTA (plasma transferred arc welding) process. The experiments were conducted based on five-factor five-level central composite rotatable design with full replication technique and a mathematical model was developed using response surface methodology. Furthermore, the response surface methodology was also used to optimize the process parameters that yielded the lowest percentage of dilution.
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: Based on the configuration feature of keyhole PAW welds, a combined heat source model is proposed for the numerical analysis of temperature fields in keyhole plasma arc welding process as mentioned in this paper, which accounts for the keyhole effect indirectly and the volumetric distribution characteristics of plasma heat intensity along the direction of the workpiece thickness.
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 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.
12 Feb 2009
TL;DR: In this paper, the effects of laser powers and their densities on the weld penetration and the formation of sound welds were investigated in welding of Type 304 austenitic stainless steel, A5052 aluminum alloy or high strength steel plates with four laser beams of about 0.12 to 1 mm in focused spot diameter, and their welding phenomena were observed with high-speed video cameras and X-ray transmission real-time imaging system.
Abstract: Fiber lasers have been receiving considerable attention because of their advantages of high power, high beam quality and
high efficiency, and are expected as one of the desirable heat sources for high-speed and deep-penetration welding. In
our researches, therefore, the effects of laser powers and their densities on the weld penetration and the formation of
sound welds were investigated in welding of Type 304 austenitic stainless steel, A5052 aluminum alloy or high strength
steel plates with four laser beams of about 0.12 to 1 mm in focused spot diameter, and their welding phenomena were
observed with high-speed video cameras and X-ray transmission real-time imaging system. It was found that the laser
power density exerted a remarkable effect on the increase in weld penetration at higher welding speeds, but on the other
hand at low welding speeds deeper-penetration welds could be produced at higher power. Laser-induced plume behavior
and its effect on weld penetration, and the mechanisms of spattering, underfilling, porosity and humping were elucidated,
sound welds without welding defects could be produced under the improved welding conditions. In addition, importance
of the development of focusing optics and the removal of a plume during remote welding will be emphasized in terms of
the stable production of constant deep-penetration welds and the reduction in welding defects in high power laser
welding.
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 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 paper, the effects of welding method, peak temperature, and cooling rate on the susceptibility to intergranular corrosion of alloy 690 weldments were investigated, and the experimental results reveal that the laser beam welding process with cooling rate of around 212.6°C/s can be produced with much less mass loss and a lower value of maximum reactivation current density/maximum anodic current density than with the gas tungsten arc welding process, where cooling rate is at around 17−20.6
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.
TL;DR: In this paper, tests conducted in the IIS Special Welding Process laboratory with the collaboration of Arroweld Italia pertaining to two technological subjects of considerable interest, such as "cladding" with high corrosion resistance alloys and thin layer brazing, both using continuous wire welding methods with gas shielding, in an entirely particular version known as "cold metal transfer" (CMT®).
Abstract: As is well known in the field of welding technology, the heat input in a joining process is a defining factor of the results that can be obtained in numerous aspects directly affecting metallurgical phenomena, technological properties and the integrity of the welded joint, as well as deformations and residual stresses. Furthermore, a different heat input can be decisive on process productivity and economy. This article concerns tests conducted in the IIS Special Welding Process laboratory with the collaboration of Arroweld Italia pertaining to two technological subjects of considerable interest, such as ‘cladding’ with high corrosion resistance alloys and thin layer brazing, both using continuous wire welding methods with gas shielding, in an entirely particular version known as ‘Cold Metal Transfer – CMT®’. In the case of ‘cladding’, the most critical aspects of anticorrosion overlay, such as penetration into the substrate and level of dilution, which frequently compromise the intrinsic corrosion resista...
TL;DR: In this paper, the effect of TiO2 additions in fluxes on the mechanical properties and microstructure of the weld metal formed during Submerged Arc Welding (SAW) of ASTM A-36 steel plates was studied.
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.
TL;DR: In this paper, the spectral analysis is performed in two stages: dimensionality reduction is accomplished using a feature selection algorithm and, after that, an artificial neural network carries out the spectral identification task.
Abstract: The validity of a processing technique, based on feature selection and artificial neural networks, when applied to arc-welding on-line quality monitoring is analyzed. An optical fiber embedded within the welding torch captures the plasma radiation, which is delivered to a CCD spectrometer. In the proposed solution the spectral analysis is performed in two stages: dimensionality reduction is accomplished using a feature selection algorithm and, after that, an artificial neural network carries out the spectral identification task. The validity of the technique has been successfully demonstrated by means of several experimental welding tests.
TL;DR: The use of high-strength aluminum alloys is increasing in shipbuilding industry, particularly for the design and construction of war ships, littoral surface craft and combat ships, and fast passenger ships.
TL;DR: In this article, the authors investigated the use of laser cladding technology to deposit a high quality and erosion resistant protection shield on the leading edge of low pressure (LP) turbine blades.
Abstract: Reliable and efficient power generation is a major global issue due to both political and environmental concerns. Nevertheless, many critical components, particularly the blades of the low pressure (LP) side of power generating steam turbines, are subject to failure due to severe erosion at the leading edges. Since taking machines offline for maintenance and removal of damaged blade for repair is extremely expensive, increasing the service life of these critical components offers significant economic and political benefits. Conventional techniques to increase service life include brazing of an erosion shield at the leading edge of the turbine blade, open arc hardfacing, and cladding with erosion resistant materials using gas tungsten, manual metal or plasma transferred arc welding. The authors have been investigating since 2001 the use of laser cladding technology to deposit a high quality and erosion resistant protection shield on the leading edge of LP blades. The project has demonstrated the fe...