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Showing papers on "Arc welding published in 2000"


Journal ArticleDOI
TL;DR: In this paper, high vacuum electron beam welding (EBW-HV), CO2 laser beam welding and gas tungsten arc welding (TIG), as well as optical microscope (OM) observation and microhardness measuring of 0.5 mm thick sheets of commercial purity titanium (C.P. Ti) have been studied via EBW, HV, LBW and TIG.
Abstract: Microstructures, properties and technical parameters of welding specimen of 0.5 mm thick sheets of commercial purity titanium (C.P. Ti) have been studied via high vacuum electron beam welding (EBW-HV), CO2 laser beam welding (LBW) and gas tungsten arc welding (TIG), as well as optical microscope (OM) observation and microhardness measuring. The results indicate that the EBW is more suitable for C.P. Ti sheets welding, and the welding seam without defects can be obtained. The tensile strength and microhardness of joints are corresponding to matrix structure. The full-penetration butt welds are obtained by TIG, but they have many defects such as wide weld-seam, big deformation and coarse grains. The LBW has many advantages such as the narrowest weld-seam, the least deformation and the finest grains. The fine grains are good for properties of weld seam, but the LBW should be studied again for the reasons of unstable welding technologies and strict condition.

224 citations


Journal ArticleDOI
TL;DR: In this paper, the authors evaluated the use of activated flux TIG (ATIG) welding for the austenitic stainless steels with fluxes of only one major component and found that even the very simple flux that was used can greatly increase the penetration of the weld bead.

205 citations


Journal ArticleDOI
TL;DR: The most dominant mechanism for increased penetration is considered to be arc constriction rather than a change in the surface tension of the molten pool as mentioned in this paper, which is the most common mechanism used in tungsten inert gas welding.
Abstract: Mechanisms by which active fluxes increase the penetration of conventional tungsten inert gas (TIG) welds (so called A-TIG welds) are reviewed. The most dominant mechanism for increased penetration is considered to be arc constriction rather than a change in the surface tension of the molten pool. An experimental programme of work was carried out using A-TIG flux in combination with a number of welding processes. The plasma process was investigated as it gives greater penetration than conventional TIG welding by increasing current density. The CO2 laser and electron beam processes which do not rely on a current carrying arc as the heat source for welding were also investigated. Macrosections taken from the welds made by these processes showed that the A-TIG flux was only effective when the weld pool was produced by an arc or plasma. Where there was no arc or plasma present, the flux had little effect.

183 citations


Patent
24 Nov 2000
TL;DR: In this article, the voltage and current conditions of the welding arc are instantly transferred within the visual range of the helmet wearing operator by the use of lights, illuminated bar graphs, light projections, illuminated see-through displays, or the like, located in proximity to the helmet viewing window.
Abstract: Apparatus for monitoring manual arc welding procedures for providing to the welder real-time monitoring of the welding characteristics to achieve optimum welds. The voltage and current conditions of the welding arc are instantly transferred within the visual range of the helmet wearing operator by the use of lights, illuminated bar graphs, light projections, illuminated see-through displays, or the like, located in proximity to the helmet viewing window wherein, through such monitoring, the operator is constantly aware of the arc conditions during welding.

141 citations


Journal ArticleDOI
TL;DR: In this paper, the use of fuzzy logic in the Taguchi method to optimise the submerged arc welding process with multiple performance characteristics is reported, including arc current, arc voltage, welding speed, electrode protrusion, and preheat temperature.
Abstract: The use of fuzzy logic in the Taguchi method to optimise the submerged arc welding process with multiple performance characteristics is reported in this paper. An orthogonal array, the signal-to-noise ratio, multiresponse performance index, and analysis of variance are employed to study the performance characteristics in the submerged arc welding process. The process parameters, namely arc current, arc voltage, welding speed, electrode protrusion, and preheat temperature are optimised with considerations of the performance characteristics, including deposition rate and dilution. Experimental results are provided to confirm the effectiveness of this approach.

118 citations


Patent
15 Jun 2000
TL;DR: In this paper, information pertaining to characteristics of metal welding electrode wire and which characteristics are useful in connection with adjusting welding parameters in an arc welding process and selecting between operating modes in a welding system are encoded on welding wire and/or on other memory components such as bar code labels and tags, RFID cards, IC cards, and Touch Memory buttons.
Abstract: Information pertaining to characteristics of metal welding electrode wire and which characteristics are useful in connection with adjusting welding parameters in an arc welding process and/or selecting between operating modes in a welding system are encoded on welding wire and/or on other memory components such as bar code labels and tags, RFID cards and tags, IC cards, and Touch Memory buttons, and the memory device is scanned prior to and/or at the point of use of the welding wire for enabling tracking of product distribution, manual and/or automatic selection of an operating mode for the welding system, manual and/or automatic adjustment of welding parameters in a given operating mode, consumables inventory, and the like.

96 citations


Patent
16 Mar 2000
TL;DR: An electric arc welding apparatus for depositing molten metal from an advancing welding wire into a weld puddle in an open root between two juxtapositioned plates where the root extends in a welding path and is formed by converging walls terminating in generally parallel walls spaced to define a gap as discussed by the authors.
Abstract: An electric arc welding apparatus for depositing molten metal from an advancing welding wire into a weld puddle in an open root between two juxtapositioned plates where the root extends in a welding path and is formed by converging walls terminating in generally parallel walls spaced to define a gap, which apparatus comprises a contact holder with a wire outlet, a switching power supply directing welding current to the wire as the wire passes from the outlet toward the open root, with the advancing wire defining an electrode stick out between the contact holder and the weld puddle, a circuit for sensing the length of the stick out, and control means for adjusting the welding current as a function of the sensed stick out length.

90 citations


Journal ArticleDOI
TL;DR: In this paper, the effect of hydrogen in argon as a shielding gas in arc welding of austenitic stainless steel was investigated and it was shown that hydrogen addition to argon changes the static characteristic of the welding arc.

84 citations


Journal ArticleDOI
TL;DR: In this article, gas tungsten-arc welded 18Ni (250-grade) maraging steel was used with two different filler wires: one matching the base material in composition and the other with higher cobalt but lower molybdenum and titanium contents.
Abstract: Sheet material specimens from 18Ni (250-grade) maraging steel were gas tungsten-arc welded using two different filler wires: one matching the base material in composition and the other with higher cobalt but lower molybdenum and titanium contents. Welding was carried out both in constant-current and pulsed modes. Post-weld aging was performed at three different temperatures, viz., 425, 480 and 520°C. Metallographic characterization revealed pronounced segregation, presumably of Ti and Mo, along interdendritic and intercellular boundaries in the weld metal produced with filler of matching composition. This led, during subsequent aging, to austenite reversion at temperatures much lower than in wrought (unwelded) material. Segregation and austenite reversion were not noticed when Ti and Mo contents were reduced in the filler wire, except at the highest aging temperature used. The use of pulsed welding resulted in some grain refinement, but the effect was not considerable.

81 citations


Journal ArticleDOI
TL;DR: An analytical solution for the temperature-rise distribution in arc welding of short workpieces is developed based on the classical Jaeger's moving heat-source theory to predict the transient thermal response as mentioned in this paper.
Abstract: An analytical solution for the temperature-rise distribution in arc welding of short workpieces is developed based on the classical Jaeger’s moving heat-source theory to predict the transient thermal response. It, thus, complements the pioneering work of Rosenthal and his colleagues (and others who extended that work), which addresses quasi-stationary moving heat-source problems. The arc beam is considered as a moving plane (disc) heat source with a pseudo-Gaussian distribution of heat intensity, based on the work of Goldak et al. It is a general solution (both transient and quasi-steady state) in that it can determine the temperature-rise distribution in and around the arc beam heat source, as well as the width and depth of the melt pool (MP) and the heat-affected zone (HAZ) in welding short lengths, where quasi-stationary conditions may not have been established. A comparative study is made of the analytical approach of the transient analysis presented here with the finite-element modeling of arc welding by Tekriwal and Mazumder. The analytical model developed can determine the time required for reaching quasi-steady state and solve the equation for the temperature distribution, be it transient or quasi-steady state. It can also calculate the temperature on the surface as well as with respect to the depth at all points, including those very close to the heat source. While some agreement was found between the results of the analytical work and those of the finite-element method (FEM) model, there were differences identified due to differences in the methods of approach, the selection of the boundary conditions, the need to consider image heat sources, and the effect of variable thermal properties with temperature. The analysis presented here is exact, and the solution can be obtained quickly and in an inexpensive way compared to the FEM. The analysis also facilitates optimization of process parameters for good welding practice.

74 citations


Journal ArticleDOI
TL;DR: In this paper, the microstructure, crack sensitivity, and porosity of double-sided arc welding (DSAW) weldments were studied systematically, and it was found that the shape and size of porosity is related to solidification substructure.
Abstract: Due to its popularity and high crack sensitivity, 6061 aluminum alloy was selected as a test material for the newly developed double-sided arc welding (DSAW) process. The microstructure, crack sensitivity, and porosity of DSAW weldments, were studied systematically. The percentage of fine equiaxed grains in the fully penetrated welds is greatly increased. Residual stresses are reduced. Porosity in the welds is reduced and individual pores are smaller. It was also found that the shape and size of porosity is related to solidification substructure. In particular, a weld metal zone with equiaxed grains tends to form small and dispersed porosity, whereas elongated porosity tends to occur in columnar grains.

Patent
15 Jun 2000
TL;DR: In this article, an electric arc welding apparatus comprising at least a first consumable electrode and a second consumable electrodes movable in unison along a welding path between the edges of two adjacent, mutually grounded plates, including a first power supply for passing a first welding current at a first low frequency between the first electrode and the two plates, and an output switching network operated at a given low frequency from the two terminals across one of the electrodes and the plates, is presented.
Abstract: An electric arc welding apparatus comprising at least a first consumable electrode and a second consumable electrode movable in unison along a welding path between the edges of two adjacent, mutually grounded plates, a first power supply for passing a first welding current at a first low frequency between the first electrode and the two plates, a second power supply for passing a second welding current at a second low frequency between the second electrode and the two plates, where each of the power supplies includes a three phase voltage input operated at line frequency, a rectifier to convert the input voltage to a DC voltage link and a high frequency switching type inverter converting the DC voltage link to a high frequency AC current, an output rectifier circuit to provide a positive voltage terminal and a negative voltage terminal, and an output switching network operated at a given low frequency for directing a pulsating welding current at the given low frequency from the two terminals across one of the electrodes and the plates, and a circuit for independently adjusting the given low frequency so the value of the first low frequency of the first power supply is different from the second low frequency of the second power supply.


Journal ArticleDOI
TL;DR: It was found that the error rate predicted by the artificial neural network was smaller than that predicted byThe multiple regression analysis, in terms of the width and depth of the back-bead.

Journal Article
TL;DR: In this paper, the melting efficiency of a finite element model (FEM) simulation through the energy input rate Q is compared with numerical and measured values reported by Christensen, Krutz and Goldak using both Gaussian and ellipsoidal power density distribution functions.
Abstract: The easiest ways to simulate welding processes are with the decoupled heat equation of Navier-Stokes or magnetohydrodynamic (MHD) equations. To decouple the heat equation, functions of energy input rate Q, heat flux per unit area (or volume) per unit time q and effective thermal conductivity Keff that generate a temperature field by the heat equation must be considered. More precisely, the traditional heat source models (Gaussian and ellipsoidal) and Keff functions must be used cautiously because of the critical responsibility to represent the magnetohydrodynamics of the arc and the fluid mechanics of the weld pool. When thermal efficiency is introduced in the decoupled heat equation, both the complex and nonintuitive physics of the arc and dilution (through melting efficiency) are incorporated in the heat transfer analysis. This paper allows the melting efficiency to be related to the process variables in a finite element model (FEM) simulation through the energy input rate Q. Transient thermal histories and sizes of fusion and heataffected zones are compared with numerical and measured values reported by Christensen, Krutz and Goldak using both Gaussian and ellipsoidal power density distribution functions. The FEM code COSMOS, produced by Structural Research and Analysis Corp., was used for all the simulations described in the following sections.

Patent
28 Sep 2000
TL;DR: In this paper, a machine tool or die that is fabricated from thermally spray-formed steel is easily repaired by cleaning, roughing and covering the surface to be repaired by a cold-spray layer of metal and then forming a weldment by conventional electric welding processes.
Abstract: A machine tool or die that is fabricated from thermally spray-formed steel is easily repaired by cleaning, roughing and covering the surface to be repaired by a cold-spray layer of metal and then forming a weldment by conventional electric welding processes. The repaired surface is then finished by conventional machining, grinding and polishing and then the tool is put back into service.


Journal ArticleDOI
TL;DR: Rats exposed to the welding fume for 4 h did not show any significant respiratory system toxicity, and particle adsorption took place principally in the lower respiratory tracts, including bronchioles,Alveolar ducts, alveolar sacs, and alveoli.


Patent
27 Sep 2000
TL;DR: An electric arc welder comprising a plurality of power supplies connected to a single welding station with a D.C. input for passing an arc welding current across an electrode and workpiece is described in this paper.
Abstract: An electric arc welder comprising a plurality of power supplies connected to a single welding station with a D.C. input for passing an arc welding current across an electrode and workpiece, each of the power supplies including a switching type inverter with an output D.C. current determined by a signal applied to the input of the power supply, a circuit connecting the output D.C. currents in parallel at the input of the welding station, a feedback circuit including a sensor for creating a current signal representing the arc current, a command signal source, and a circuit for creating a master current signal based upon the sensed current signal and the command signal, and a circuit for applying said master current signal to the input of the plurality of power supplies whereby the D.C. current to the D.C. input of the welding station is equally shared by the power supplies.

Patent
17 Mar 2000
TL;DR: In this article, a welding method capable of increasing or decreasing a welding wire feeding speed during welding is presented, where, after short-circuiting is detected, the welding wire feed speed is decreased, and, after a transfer to arcing by being freed from short circuiting, the wire feed rate is increased.
Abstract: A welding method capable of increasing or decreasing a welding wire feeding speed during welding, wherein, after short-circuiting is detected, a welding wire feeding speed is decreased, and, after a transfer to arcing by being freed from short-circuiting is detected, a welding wire feeding speed is increased.

Journal Article
TL;DR: In this article, an arc light sensor has been developed to deect argon atom spectral lines in gas tungsten arc welding, and the relationship between the argon lines and the welding parameters has been derived from the theoretical model.
Abstract: Sensing plays a key role in automating and controlling welding processes. In recent decades, arc light sensing has been studied for arc length control, joint tracking and droplet trans- fer detection in arc welding. However, the current technology relies on experi- mental data and lacks theoretical foun- dation. To improve measurement accu- racy, this work addresses the theoretical foundation for arc light sensing. A theo- retical model has been developed to cor- relate arc light radiation to welding pa- rameters. Distributions of different radiant sources in the arc column are studied. It is found that the distributions of the ions of the shielding gas and the vapors of the base metal and tungsten are not even, while that of the shielding gas atoms is. This suggests the spectral lines associated with the shielding gas atoms can be used to improve the accu- racy of arc light sensing. Hence, an arc light sensor has been developed to de- tect argon atom spectral lines in gas tungsten arc welding. The relationship between the argon lines and the welding parameters has been derived from the theoretical model. Joint tracking exam- ples showed the effectiveness of the de- veloped method in improving accuracy.

Journal ArticleDOI
J I Lee1, S Rhee1
01 Jun 2000
TL;DR: In this article, a prediction regression equation of the welding process parameters in order to obtain the desired geometry of the back-bead in butt welding, a form of gird welding, is presented.
Abstract: The purpose of this study is to find a prediction regression equation of the welding process parameters in order to obtain the desired geometry of the back-bead in butt welding, a form of g...

Patent
02 May 2000
TL;DR: In this article, an arc welding machine is described for providing a continuous feed electrode to a weld site, which includes a line frequency transformer having a primary winding, a first secondary winding, and a second secondary winding (e.g., an extension winding, separate winding, etc.).
Abstract: An arc welding machine is disclosed for providing a continuous feed electrode to a weld site. The arc welding machine includes a line frequency transformer having a primary winding, a first secondary winding, and a second secondary winding (e.g., an extension winding, a separate winding, etc.). The first secondary winding provides a welding power having a first voltage at a welding power output terminal. The second secondary winding provides a second welding power having a second higher voltage at an input terminal of a switch, the switch being controlled to provide a pulsed power at the welding power output terminal. According to one feature, the arc welding machine produces a pulsed power having a fixed pulse width and a fixed frequency, the fixed pulse width and fixed frequency being substantially free of operator adjustment.

Patent
06 Nov 2000
TL;DR: In this article, the second base current is passed by comparing the welding voltage v and arc holding voltage Vc to reduce the spatter at the arc regenerating time at the short circuit term.
Abstract: PURPOSE: To reduce spatters at the arc regenerating time by passing the second base current during the short circuit term of the body to be welded and wire, then by cutting the second base current and by returning to a pulse current or the first current. CONSTITUTION: A integrating circuit 141, comparators 151, 152 and signal reversing element 161, analog switching element 193 are arranged in the equipment circuits. The welding voltage detected by a voltage detector is inputted into the comparator 151 and the arc maintaining voltage Vc is inputted into the comparator 151 from an arc maintaining voltage setting part 22 as well. When a short circuit is caused between the wire and the body to be welded during the welding, the welding voltage v is reduced and becomes a short circuit voltage. In this case, the second base current IB 2 having higher value than that of the first base current IB 1 is passed by comparing the welding voltage v and arc holding voltage Vc. At the short circuit releasing time, the second base current IB 2 is cut and returned to the original. With this method, the spatter at the arc regenerating time is reduced. COPYRIGHT: (C)1986,JPO&Japio

Journal ArticleDOI
TL;DR: In this article, a new mathematical description of a heat-source has been formed to represent the common in-service welding process, i.e. vertical-up and vertical-down manual metal arc (MMA) welding with hydrogen controlled electrodes.

Journal ArticleDOI
TL;DR: In this paper, four mathematical models for calculation of melting rate in arc fusion welding with a wire in coil form are presented. But the results obtained show that they are very accurate, simple and applicable to practice.

Journal ArticleDOI
TL;DR: Experimental results presented include characterization of plant uncertainty and of the effect in control performance of various available knobs, in particular in the presence of plates with variable geometry.
Abstract: This application paper addresses the use of adaptive predictive control on arc welding trailing centerline temperature control. For tackling the high level of uncertainty in the process the multivariable multipredictive adaptive regulator (MUSMAR) adaptive algorithm, relying on separate estimation of predictive models is used. Experimental results presented include characterization of plant uncertainty and of the effect in control performance of various available knobs, in particular in the presence of plates with variable geometry.

Journal ArticleDOI
TL;DR: In this paper, the performance of the pulsed-current gas metal arc welding (GMAW) process for vertical-up weld deposition of steel has been found to be superior over the use of the short-circuiting arc GMAW process with respect to the tensile, impact, and fatigue properties of the weld joint.
Abstract: The performance of the pulsed-current gas metal arc welding (GMAW) process for vertical-up weld deposition of steel has been found to be superior over the use of the short-circuiting arc GMAW process with respect to the tensile, impact, and fatigue properties of the weld joint. The microstructure, weld geometry, and mechanical properties of a pulsed-current weld joint are largely governed by the pulse parameters, and correlate well to the factor φ, defined as a summarized influence of pulse parameters such as peak current, base current, pulse-off time, and pulse frequency. The increase of φ has been found favorable to refine the microstructure and enhance the tensile strength, Cv toughness, and fatigue life of a weld joint. The fatigue life of a short-circuiting arc weld joint has been found to be markedly reduced due to the presence of an undercut at the weld toe and incomplete side-wall fusion of the base material.

Patent
Reinhard Fried1, Josef Artelsmair1
17 Nov 2000
TL;DR: In this paper, the adhesive layer consists of individual weld or anchor points produced by a weld process, especially a light arc welding process involving melting a preferably continuous welding wire so that the point is of a preferred ball- or mushroom-like shape.
Abstract: The method involves applying an adhesive layer (3) to a surface (9) of a metal base (2) to which a preferred non-metallic material (5) is to be applied. The adhesive layer consists of individual weld or anchor points (4) produced by a weld process, especially a light arc welding process involving melting a preferably continuous welding wire so that the point is of a preferred ball- or mushroom-like shape. Independent claims are also included for the following: a compound structure of metallic and non-metallic materials.