Shielding gas

About: Shielding gas is a research topic. Over the lifetime, 6697 publications have been published within this topic receiving 58668 citations.

Effects of shielding gas composition on arc behaviors and weld formation in narrow gap tandem GMAW

Abstract: In narrow gap gas metal arc welding (GMAW), it is useful to understand the arc behaviors to ensure the weld quality. Arc behaviors are strongly affected by the shielding gas composition. In this study, a three-component shielding gas mixture was used in tandem narrow gap pulsed GMAW, and the effect of its composition on arc behaviors and weld formation were investigated. The shielding gas included argon, carbon dioxide, and helium. The arc behaviors and electrical characteristics were recorded by a high-speed camera and an electrical signal acquisition system. The results show that the arc behaviors in different shielding gas are different. The arc expands and the arc length decreases with the increase of CO2 content or helium content. The arc is the widest when the shielding gas is 80%Ar10%CO210%He. The weld shape was observed, and it was found that the weld width increases first and then decreases with increasing of the CO2 content. When the helium content is below 15%, the weld width increases as the helium content increases, but when the helium is 15%, the weld width drops due to the decrease of arc length. When the helium content is above 15%, the weld width continues to increase as the helium content increases. The largest weld width can be obtained in 80%Ar10%CO210%He.

Metal cored electrode for open root pass welding

Abstract: A method and apparatus of forming a root bead in a gap between spaced ends of at least one workpiece. The gap includes an open root. A metal cored electrode having a metal sheath and core materials is used to for the root bead in the open root. The core materials include little or no slag forming agent. The metal cored electrode is advanced at a given wire feed rate toward the open root to weld the ends together by at least partially filling the open root in a first weld pass. A welding current having a controlled waveform is used. The waveform includes a succession of welding cycles each having a short circuit portion and a metal the metal cored electrode and to cause the metal cored electrode to melt and transfer to the ends in the open root to form a root bead. The formed root bead has little or no slag on the upper surface of the root bead. A shielding gas is used to at least partially protect the molten metal in the open root from the atmosphere.

Grey-based taguchi method for optimization of bead geometry in laser bead-on-plate welding

Abstract: This study focused on the bead on plate welding of super austenitic stainless steel sheets using laser welding. Taguchi Technique is applied to plan and conduct the experiments. The output variables such as Bead Width (BW), Depth of Penetration (DP) and Aspect Ratio (AR) were measured from the bead on plate weld. These output variables were determined according to beam power, travel speed and focal position. The bead on plate welding was performed on two different shielding gases like argon and helium. The shielding gas affects the weld bead characteristics such as shape, penetrationwelding efficiency etc. It is appropriate to apply Taguchi’s technique to a complex system like welding process. Therefore, this study is made to determine the near optimal welding process parameters (beam power, travel speed and focal position) using grey relational analysis by simultaneously considering multiple output parameters (bead width, depth of penetration and aspect ratio). Taguchi experimental design for determining welding parameters was successful. The gray relational grade helped to quantify the integrated performance of bead on plate welding of laser beam welding process. Confirmation experiment has been conducted to validate the optimized parameters. The predicted and initial parameters have the better aspect ratio. The optimal welding conditions were identified in order to increase the productivity and minimize the total operating cost. The process input parameters effect was determined under the optimal welding combinations.

Effect of shield gas composition on surface tension of steel droplets in a gas-metal-arc welding arc

Abstract: A technique for in-situ measurement of the surface tension of molten steel droplets in a gas-metal-arc welding plasma is described. Surface tension measurements obtained using this method are reported for ER 70S-6 wire, with varying shielding gas compositions, and compared with previously reported results. The in-situ technique is found to produce results consisten with values found in the literature, while incorporating the effects of alloy composition and arc atmosphere.

An investigation on the effects of gases in GTA welding of a wrought AZ80 magnesium alloy

Abstract: Magnesium alloy components are frequently gas tungsten arc welded despite magnesium's high thermal diffusivity. Gases such as argon, helium, -and nitrogen - enriched or not with hydrogen - have been investigated to determine if melting, and in particular weld penetration, can be increased. Images of the arcs, voltage readings, dimensions, defects, and microstructure of weld fusion zones have been examined. Due to a greater first ionization potential, helium increased the constant-current voltage and created more melting than argon. With diatomic gases such as nitrogen and hydrogen, voltage and weld dimensions were even further increased. However, hydrogen caused porosity, and nitrogen interacted with magnesium by leaving a nitride deposit at weld surfaces. While consequences of alloying with nitrogen were probably not disadvantageous, hydrogen pores were of greater concern. Both welding parameters and hydrogen concentration in the arc atmosphere were important in controlling porosity. The two-dimensional heat-flow conditions of fully penetrating welds were capable of eliminating porosity and could make welding with hydrogen additions a possibility to consider.