Monitoring of Welding Process Parameters in Gas Tungsten Arc Welding of Carbon Steel Weldments

Results of present study show the possibilities to monitor and control the automatic gas tungsten arc welding process using additional filler rod, and investigate the evolution of microstructure and the mechanical characteristics of carbon steel weldments joint under the different welding parameters: welding current, arc voltage, and travel speed. Three types of weldments were produced and tested: buildup welds, U-grooved samples, and butt welds. Penetration and depth of heat affected zone in all types of welds are influenced especially by the welding current. Dendrite structure formed after welding gives a good indication of the thermodynamic processes during liquid metal solidification, welds are free from defects. The welded joints showed that crystal orientation and shape in the weld zone depend on thermodynamic processes during solidification and welding mode. The frequency and size of the successive droplets of the molten metal from the filler rod has been registered by piezoelectric sensor and due to the collected data the welding parameters and herewith the geometry and structure of heat affected zone and weld bead have been controlled.