Geometric Model of the Weld Bead in DC and Square AC Submerged Arc Welding of 2.25 Cr-1 Mo Heat Resistant Steel

Abstract

Weld bead shape is an important feature in arc welding that governs the mechanical behavior of the joint. The weld bead is significantly influenced by the type of power source used like alternating current (AC) or direct current (DC) as they affect the extent of heat generated at the electrode and workpiece. The present study identifies a way to represent the weld bead shape through composite geometrical functions. A case of bead geometry produced using DC and AC power source in submerged arc welding of 2.25 Cr-1 Mo is presented. The direct current electrode negative (DCEN) and direct current electrode positive (DCEP) polarities in DC power source and square waveform in the AC power source are used to deposit beads using constant welding conditions (like current and speed). The macrographs of the welded sample show different geometrical approximations for weld shape in DCEP, DCEN, and AC square waveform welds. Among the different polarity, the bead shape of an AC square waveform is distinct as compared to DC polarities and shows the ability to customize deposition and penetration by changing the frequency and the electrode negative ratio.