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.

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

This paper presents extensive investigations about the influence of He-additions to argon TIG-arc properties. Results of diagnostic methods, numerical simulations and welding trials are combined to improve the comprehension about the mode of action of gas mixtures. Additionally, selected results of the investigation with H2- and N2-additions are summarized. The investigations show that all gas additions cause an increase of the heat input into the workpiece. However, the stagnation pressure depends on the gas composition: He-additions result in a decrease of the stagnation pressure which depends on the arc length, whereas H2-and N2-additions increase the pressure. By a systematic choice of the gas mixture the weld depth and also the maximum feed speed can be influenced.

Numerical and Experimental Studies of the Influence of Process Gases in Tig Welding

An inert gas for TIG-welding of metals has a constituent of 1.5 to 2.0 vol.% of hydrogen, and 2.0 to 5.0 vol.% of helium, and argon residual. An independent claim is given for a gas mixture as inert gas for the welding procedure.

Shielding gas for TIG-welding of metals

Die Erfindung betrifft ein Schutzgas zum WIG-Schweisen von Metallen mit einem Wasserstoffanteil von 1,5% bis zu 2%, einem Heliumanteil von 2% bis zu 5%, Rest Argon. Mit dem erfindungsgemasen Schutzgasgemisch werden sowohl beim manuellen als auch mechanisierten Schweisen wesentliche anwendungstechnische Vorteile erzielt. Das Fliesverhalten wird verbessert, die Tendenz zu Nahtfehlern wird reduziert. Das Einbrandverhalten wird bei gleichem Strom deutlich verbessert und der Beizaufwand deutlich vermindert. Das Ergebnis beim Schweisen insbesondere von hochlegierten Stahlen wird wesentlich verbessert.

P. Ortega

Papers

Helium : a lightweight gas but a heavyweight performer