Arc welding

About: Arc welding is a research topic. Over the lifetime, 25393 publications have been published within this topic receiving 168182 citations.

Mechanism and Microstructure of Oxide Fluxes for Gas Tungsten Arc Welding of Magnesium Alloy

Abstract: Five single oxide fluxes—MgO, CaO, TiO2, MnO2, and Cr2O3—were used to investigate the effect of active flux on the depth/width ratio in AZ31B magnesium alloy. The microstructure and mechanical property of the tungsten inert gas (TIG) welding seam were studied. The oxygen content in the weld seam and the arc images during the TIG welding process were analyzed. A series of emission spectroscopy of weld arc for TIG welding for magnesium with and without flux were developed. The results showed that for the five single oxide fluxes, all can increase the weld penetration effectively and grain size in the weld seam of alternating current tungsten inert gas (ACTIG) welding of the Mg alloy. The oxygen content of the welds made without flux is not very different from those produced with oxide fluxes not considering trapped oxide. However, welds that have the best penetration have a relatively higher oxygen content among those produced with flux. It was found that the arc images with the oxide fluxes were only the enlarged form of the arc images without flux; the arc constriction was not observed. The detection of arc spectroscopy showed that the metal elements in the oxides exist as the neutral atom or the first cation in the weld arc. This finding would influence the arc properties. When TIG simulation was carried out on a plate with flux applied only on one side, the arc image video showed an asymmetric arc, which deviated toward the flux free side. The thermal stability, the dissociation energy, and the electrical conductivity of oxide should be considered when studying the mechanism for increased TIG flux weld penetration.

Wear and corrosion resistance of PTA weld surfaced Ni and Co based alloy layers

Abstract: Microstructural development in the hardfacing alloys NiCrBSi and Stellite 6 resulting from the commercially available ‘open arc’ and ‘spray and fuse’ coating techniques was compared with that resulting from the plasma transferred arc (PTA) weld surfacing process. Denser eutectic structures were observed in the case of PTA weld surfaced layers of Stellite 6 in comparison with the open arc weld surfacing process. The shapes of both carbides and borides in the 16C alloy (NiCrBSi type) coated by PTA processing were observed to have coarse morphology, while the spray and fuse layers showed needlelike morphology with finer distribution. The possible thermal history during each coating process is discussed. Based on microstructural observation, the hardness, wear resistance, and corrosion behaviours are reported. As expected, the alloy properties are directly related to the microstructural constituents.

Influence of metal vapour on arc temperatures in gas-metal arc welding: convection versus radiation

Abstract: The presence of metal vapour in gas–metal arc welding has been shown to have two strong effects on the arc plasma: a decrease in temperature throughout the arc, and the formation of a local temperature minimum near the arc axis. These effects have been attributed, on the basis of different computational models, to either the increased radiative emission associated with the presence of metal vapour in the arc plasma, or the influence of the metal vapour influx on convective flow in the arc. This question is investigated using a three-dimensional computational model in which the production and the transport of metal vapour are taken into account self-consistently. Parameters relevant to welding of thin sheets of aluminum are examined. For these conditions, it is found that the first effect (the decrease in temperature throughout the arc) is due to both the increased radiative emission and the influence of the metal vapour influx on flow. The second effect (the local temperature minimum, which in this case occurs just below the wire electrode) is a consequence of the influence of aluminum vapour produced from the wire electrode on flow in the arc. By examining published results and the energy balance in the plasma, it is shown that for welding of steel with higher arc currents, the increased radiative emission can lead to a local temperature minimum at a greater distance from the wire electrode.

Testing of work environments for electromagnetic interference.

Abstract: A challenge for pacemaker therapists is whether a patient working in an environment with the potential for electromagnetic interference (EMI) can return to their work after a pacemaker has been implanted. Common practice has been to prohibit pacemaker patients from using electric welding machines. Twelve work environments and a new method for monitoring the pacemaker rhythm in the presence of EMI were tested. The new method uses a special memory called the event record found in several Siemens Pacesetter pacemaker models. Surface ECGs with a marking system, intracardiac electrograms, and a digital monitor were used to verify the results with event records. The results from several sources of EMI are reported. Twenty-one in vivo and in vitro tests were performed in the work environments of 12 patients. Event records were useful and accurate both in vivo and in vitro. Electric arc welding machines up to 225 A did not affect these pacemakers. Arc welding machines using 1,000 A or more inhibited the in vitro test system within 1 or 2 meters of the weld or power generator. Electric welding machines with high frequency voltage superimposed on the welding current affected the pacemaker when it was within 2 meters of the power unit and 1 meter of the weld. Very large industrial degaussing coils affected pacemakers within 2 meters. The test method using event records was found to be an effective addition to monitoring the pacemaker. These results are specific for the pacemaker models tested. Such testing allows the physician to make a knowledgeable decision regarding return to work for the pacemaker patient in a high EMI environment.