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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20 Aug 1991TL;DR: In this article, an inert gas nitrogen mixture is used as a shielding gas to prevent weld hot cracking in superalloys containing zirconium and/or boron, and test data show excellent results were obtained when gas tungsten arc welding HAYNES 214 alloy which normally contains borons and zirconsium and a minimal content of titanium.
Abstract: An inert gas nitrogen mixture is used as a shielding gas to prevent weld hot cracking in superalloys containing zirconium and/or boron. The gas mixture preferably contains argon and about 2 to 8% by volume nitrogen. Test data show excellent results are obtained when gas tungsten arc welding HAYNES 214 alloy which normally contains boron and zirconium and a minimal content of titanium.
30 citations
TL;DR: In this paper, the surface tension over the weld pool, real-time monitoring data, and measured characteristics from the fusion zone region were discussed using a simple model for the TIG welding of magnesium.
Abstract: Active fluxes that are deposited on the TIG torch path before alloy melting can significantly increase weld penetrations. Several mechanisms (arc constriction, surface-tension-driven flow) for the active-TIG or A-TIG welding process have been postulated. The A-TIG welding of magnesium is discussed here using a simple model for the surface tension over the weld pool, real-time monitoring data, and measured characteristics from the fusion zone region. The chlorides selected for this investigation incorporated simple-metal elements from different group numbers (LiiaCl, CaiiaCl2, CdiibC12, PbivbCl2 and CeCl3) so that correlations between their chemistry and their effects during A-TIG welding could be established. Video recordings showed that chlorides intensified the visible light emission from the arc and affected its profile. Measurements during arc welding at a constant current demonstrated that all chlorides increased the arc voltage (thus the heat input) and the arc temperature. A-TIG weld cross sections revealed that chlorides increased fusion zone dimensions, as could be expected from greater heat inputs. While calculations suggested that surface tension might have altered weld pool circulation, specially designed experiments with low-energy-density laser beams were inconclusive. Among all tested chlorides, cadmium chloride was the most effective during A-TIG welding due to the high first ionization potential of cadmium, which correlated to several observations such as: low chloride melting, boiling, and dissociation temperatures, high welding voltage, augmented arc temperature, increased fusion zone penetration, and greater depth-to-width ratio.
30 citations
21 Jan 2009-Metallurgical and Materials Transactions B-process Metallurgy and Materials Processing Science
TL;DR: In this article, the use of an Nd:YAG laser for thin-plate AZ91 magnesium alloy welding was optimized, and the welding cross section geometries were determined by optical microscopy analysis.
Abstract: Magnesium alloys have attracted the interest of the modern manufacturing industry owing to their higher strength-to-weight ratios and heat conductivity than other alloys. Laser welding will be an important joining technique for magnesium alloys with their increasing applications in aerospace, aircraft, automotive, electronics, and other industries. The Nd:YAG laser beam has the reputation to be a rapid, precise, and easy process for welding of magnesium alloys. In this study, the use of an Nd:YAG laser for thin-plate AZ91 magnesium alloy welding was optimized. The welding cross section geometries were determined by optical microscopy analysis. Some important laser processing parameters (laser power, welding speed, and shielding gas flow) and their effects on the welding quality are discussed.
30 citations
TL;DR: In this article, the effects of shielding gas on the microstructure and localized corrosion of tube-to-tube sheet welds of SR-50A super austenitic stainless steel for seawater cooled condense were investigated in highly concentrated chloride environments.
30 citations
TL;DR: In this paper, the characteristics of laser micro-welding of thin stainless steel sheets by using a single-mode CW fiber laser with high-speed scanning system were experimentally investigated, and it was clarified that the welding bead width and depth increased with increasing the scanning velocity under a constant energy density condition and high efficient welding was expected by using high speed laser scanning with Galvano scanner.
Abstract: Problem statement: The miniaturization of components plays an important role for manufacturing in electrical and electronic industries. The joining technology of thin metal sheets has been strongly required. Laser welding with micro-beam and high-speed scanning is a promising solution in micro-welding, because it has high-potential advantages in welding heat sensitive components with precise control of heat input and minimal thermal distortion. Approach: In this study, the characteristics of laser micro-welding of thin stainless steel sheets by using a single-mode CW fiber laser with high-speed scanning system were experimentally investigated. Results: It was clarified that the welding bead width and depth increased with increasing the scanning velocity under a constant energy density condition and high efficient welding was expected by using high-speed laser scanning with Galvano scanner. The utilization of shielding gas was very effective to obtain smooth fusion bead and the combination of micro beam spot and high-speed laser scanning made it possible to obtain good overlap welding of ultra-thin stainless steel sheets. Conclusion: A faster and high quality welding could be achieved by using a single-mode fiber laser with micro-beam and high-speed scanning.
30 citations