Topic
Shielding gas
About: Shielding gas is a research topic. Over the lifetime, 6697 publications have been published within this topic receiving 58668 citations.
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01 Jan 1989
TL;DR: In this article, the authors reported the changes in droplet-transfer mode and rate during gas metal arc welding as the voltage is varied at a series of current levels, and the droplet transfer rate was found to be maximum (approximately 100 s_1) for the voltage/current combi-nation that are normally suggested by the electrode manufacturers and are converse optimum in the judgment of experienced welders.
Abstract: This study reports the changes in droplet-trans fer mode and rate during gas metal arc welding as the voltage is varied at a series of current levels. The droplet-transfer rate was found to be maximum (approximately 100 s_1) for the voltage/current combi nations that are normally suggested by the electrode manufacturers and are con sidered optimum in the judgment of experienced welders. At voltages above or below the TV-wide optimum range, the transfer rate decreased by about 10 s_1 per V in the vicinity of the optimum condition. Furthermore, statistical analysis of the arc current and voltage data showed that during operation outside the optimum range, the welding arc was unstable and the current output was very irregular with varying cycle time between each droplet transfer. At the maximum droplet-transfer rate, the droplet-transfer cycle time was very consistent and revealed a narrow rate range, which correlated with the high stability and lower spatter at these optimum operating conditions. The possibility of using the concept of maximum droplet-transfer rate range with minimum rate fluctuation and corresponding arc current-voltage signals as a means of short-circuiting welding process control and automation is being considered. At voltages below the optimum range, high-speed video recording confirmed that the short- circuiting transfer was very unstable and the arc reignited explosively. Above the optimum voltage, the arc became longer and the droplets became visibly larger, with mixed globular and short-circuiting transfer. The droplets, however, were no longer directed uniformly to the weld pool, resulting in increased spatter. arc (FCA), submerged arc (SA) and gas tungsten arc (GTA) welding. With the exception of GTA welding, all these pro cesses require a consumable electrode, which has the dual function of carrying the current that heats the weld pool and providing filler metal to complete the weld joint. This dual function has long been a topic of research. Spraragen and Lengyel (Ref. 1) reviewed the basic princi ples of an electric arc and summarized the development of the field of welding arc physics. In particular, they concluded that in the area of liquid metal transfer from the electrode to the weld pool, the electromagnetic pinch force, gravity, shielding gas drag force and surface ten sion are the major forces that act on the electrode tip. Using high-speed cinemat ographic techniques, Muller, Greene, and Rothschild (Ref. 2) found that large spher ical liquid-metal droplets in a GMA arc decreased in size with increasing current. As the electrode feed rate was continu ously increased, however, a sudden decrease in droplet size occurred at what was termed the transition current. In addition, they determined that with inert gas shielding, the droplet composition remained constant during the metal trans fer. Lesnewich (Refs. 3-5) investigated the physics of arc welding using SMA and CMA welding. Particularly, he studied the effects of welding process parameters such as current, voltage, electrode polar-
41 citations
TL;DR: Cap active flux tungsten inert gas (CA-TIG) welding using atmospheric oxygen was proposed to increase the penetration depth of a weld by using a simple nozzle cap with an air inlet as mentioned in this paper.
40 citations
Patent•
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15 Nov 2004
TL;DR: In this paper, a welding process for non-stainless steel workpieces using GTAW equipment and hydrogen containing shield gas on a first root pass is improved by using a shield gas delivery system comprising hoses or conduits made of elastomeric material having a moisture permeability coefficient of less that 275, preferably less than 100.
Abstract: A welding process for non-stainless steel workpieces (12) using GTAW equipment (20) and hydrogen containing shield gas on a first root pass is improved by using a shield gas delivery system comprising hoses or conduits (30) made of elastomeric material having a moisture permeability coefficient of less that 275, preferably less than 100, and using a tungsten electrode (22) composition comprising at least tungsten and lanthanum oxide, and preferably tungsten, lanthanum oxide, yttrium oxide and zirconium oxide Preventing moisture permeation through the elastomeric hoses (30) delivering hydrogen containing shield gas eliminates expulsion of fused weld metal during second pass filler welding over the root pass weld Electrode life is enhanced using the tungsten compounds
40 citations
TL;DR: In this article, a simulation activity was carried out in order to evaluate the relationship among chamber height, flow rates and inlet angle inclinations in a simple parallelepipedal geometry for the isolation chamber, whose width and depth were fixed, while the height was set as a variable.
40 citations
Patent•
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27 Nov 1981
TL;DR: In this article, the authors proposed to fill perforated holes thoroughly with molten metal and to prevent the formation of blowholes by subjecting iron and steel materials to be welded to laser welding by using shielding gases consisting of inert gases such as argon and helium mixed with suitable amts. of active gases according to the kinds of said materials.
Abstract: PURPOSE:To fill perforated holes thoroughly with molten metal and to prevent the formation of blowholes by subjecting iron and steel materials to be welded to laser welding by using shielding gases consisting of inert gases mixed with suitable amts. of active gases according to the kinds of said materials. CONSTITUTION:Iron and steel materials to be welded are subjected to laser welding by using shielding gases consisting of inert gases such as argon and helium mixed with suitable amts. of active gases such as oxygen, nitrogen and carbon dioxide according to the kinds of said materials. For example, if the materials to be welded are carbon steel, low alloy steel, high tensile steel, martensitic stainless steel and ferritic stainless steel, the shielding gases consisting of the compsns. of TableIare used. If the materials to be used are austenitic stainless steel, the shielding gases consisting of the compsns. of Table II are used. Thus the formation of babbles in molten metal is prevented in welding.
40 citations