Arc welding

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

In-depth study of the mechanical properties for Fe3Al based iron aluminide fabricated using the wire-arc additive manufacturing process

Abstract: An innovative wire-arc additive manufacturing (WAAM) process is used to fabricate iron aluminide alloy in-situ, through separate feeding of pure Fe and Al wires into a molten pool that is generated by the gas tungsten arc welding (GTAW) process. This paper investigates the morphologies, chemical compositions and mechanical properties of the as-fabricated 30 at% Al iron aluminide wall components, and how these properties vary at different locations within the buildup wall. The tensile properties are also measured in different loading orientations; as epitaxial growth of large columnar grains is observed in the microstructures. Fe 3 Al is the only phase detected in the middle buildup section of the wall structure, which constitutes the majority of the deposited material. The bottom section of the structure contains a dilution affected region where some acicular Fe 3 AlC 0.5 precipitates can be observed, induced by carbon from the steel substrate that was used for fabrication. The microhardness and chemical composition indicate relatively homogeneous material properties throughout the buildup wall. However, the tensile properties are very different in the longitudinal direction and normal directions, due to epitaxial growth of large columnar grains. In general, the results have demonstrated that the WAAM process is capable of producing full density in-situ-alloyed iron aluminide components with tensile properties that are comparable to powder metallurgy methods.

Measurement and prediction of energy transfer efficiency in laser beam welding

Abstract: The absorption of laser energy by the workpiece during laserbeam welding (LBW) has been studied through direct measurements of heat input obtained with a Seebeck envelope calorimeter. The experiment compared workpiece materials with contrasting thermal properties (304 stainless steel, 1018 steel, tin), and varied the laser power, travel speed, and focus spot size in order to determine their effects on two figures of merit : the energy transfer efficiency and the melting efficiency. An uncertainty analysis of the experimental measurements and calculated parameters has been included. The energy transfer efficiency during laser beam welding was found to increase with beam intensity from 0.20 to 0.90 and to stabilize at a high value at intensities greater than 30 kW/cm. No correlation with energy transfer efficiency was found for either the fusion zone depth-to-width ratio or the travel speed. Measured melting efficiencies for laser welding were found to be no higher than the theoretical maximum value of 0.48 which can be obtained with conventional arc welding processes. However, improved melting efficiency over conventional processes was obtained due to the shapes of laser welds that create two-dimensional heat flow in nominally three-dimensional heat flow applications. A mathematical model for laser welding has been developed using dimensionless parameters that relate the size of a laser weld to the net heat absorbed by the workpiece. Through application of this model, the energy transfer efficiency for continuous wave laser welding processes can be calculated after measurements of weld cross-sectional area have been made. Use of this model is expected to assist in optimization of laser welding for any type of material when it is used to select processing regimes that maximize melting efficiency and energy transfer efficiency.

Electrode and flux for arc welding stainless steel

Abstract: A flux for use in arc welding of a stainless steel workpiece with a consumable metal electrode having a precentage of chromium, which welding flux comprises a silica containing system for forming a slag on the surface of the deposited chromium-bearing alloy weld metal and a bismuth containing slag releasing agent selected from the class consisting of elemental bismuth, bismuth fluoride, bismuth sulfide, bismuth titanate, bismuth oxy carbonate, bismuth oxy-chloride and mixtures thereof. Also, there is provided an electrode employing this flux.