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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TL;DR: In this article, a number of specimens have been prepared and welded in a weld simulator, with a gas tungsten arc welding procedure and heat inputs ranging from 1.3 to 7.5MJ/m.
25 citations
TL;DR: In this article, the effect of nitrogen oxide addition to the shielding gas composition on the amount of welding fumes and gaseous emissions produced during welding was analyzed, using the standard procedures contained in EN ISO 15011-2.
Abstract: New environmental, health and safety legislation, both in the EU and in the USA, is driving the need for the study of new welding processes, and the selection of the operational procedures that will reduce fume emissions and will promote a healthier, safer and more productive work environment. Actually, there are a significant number of publications related with gas metal arc welding hazards. However, for the new gas metal arc welding hazards variants, especially cold metal transfer, there is no data available concerning fumes and gases emissions. This paper attempts to point out ways of reducing the harmful effects of gas metal arc welding processes using different filler materials, different shielding gases, different operational welding procedures and three welding processes: gas metal arc welding process and two variants, pulsed gas metal arc welding and cold metal transfer. The effect of nitrogen oxide addition to the shielding gas composition on the amount of welding fumes and gaseous emissions produced during welding is also analysed. The amount of fume and gases generated during welding was measured over a range of current intensity and arc voltages, using the standard procedures contained in EN ISO 15011-2 [1]. The data presented give a summary of the different gas metal arc welding variants and their relations to fume generation rates and gases emitted. The results obtained give indications on measures to be taken in order to reduce fume and gas emissions. In general, the minimisation of fume formation rate can be achieved by using lower energy gas metal arc welding variants, gas shielding with low CO2 and O2 contents and “green” wires.
25 citations
Patent•
24 Dec 2004
TL;DR: In this paper, the oxide film on a weld interface is removed so as to enable firm welding while suppressing generation of intermetallic compounds in a welding step, and the metal material with a galvanized layer is overlapped between both metal materials.
Abstract: PROBLEM TO BE SOLVED: To provide a different metals-welding method, in which an oxide film on a weld interface is removed so as to enable firm welding while suppressing generation of intermetallic compounds in a welding step. SOLUTION: When a steel material 1 and an aluminum alloy material 2 which are different kinds of metal are welded, the steel material 1 with a galvanized layer 1z deposited thereon as a third metal different from the above metals is overlapped between both metal materials 1, 2, so as to weld while generating a eutectic molten metal 3 of Al and Zn in a welding interface. COPYRIGHT: (C)2006,JPO&NCIPI
24 citations
TL;DR: In this article, experimental and numerical methods for visualization and quantification of process gas flows in arc welding and gives examples for their technical applications are presented. But, it is very difficult to realize this during arc welding processes; a poor access is predominant due to the covered areas inside the welding torch and temperatures of up to 20 000 K cause the strong radiation of the arc and electromagnetic fields.
Abstract: GMA welding is one of the most frequently applied welding techniques in industry. Particularly the joining of aluminium, high alloyed steels or titanium requires a cover of shielding gas in order to provide a low PPM concentration of oxygen. The result of the welding process depends essentially on the chemical and thermophysical properties of the process gas used. Consequently, it is necessary to be able to describe and to analyse its flow with respect to various influencing variables. However, it is very difficult to realize this during arc welding processes; a poor access is predominant due to the covered areas inside the welding torch and temperatures of up to 20 000 K cause the strong radiation of the arc and electromagnetic fields. This paper deals with experimental and numerical methods for visualization and quantification of process gas flows in arc welding and gives examples for their technical applications. Unlike previous work, the described methods consider the arc as a dynamic element which determinates the gas flow. Advanced Particle Image Velocimetry (PIV) and Schlieren measurement were used for characterization of the flow field in the direct vicinity of the arc in GTA and GMA welding. Furthermore, a numerical model including magneto-hydrodynamics and turbulence models was used for a detailed visualization of the flow in the free jet and in the hidden interior of the torch. It is based on a commercial CFD code which allows to model complex 3-D geometries of torch and workpiece design. Mixing effects and turbulence model were validated by oxygen measurements in the gas shield.
24 citations