Influence of welding speed on geometric and microstructural characteristics of submerged arc welding tandem arc joints

Abstract

Industry interest in submerged arc welding processes has been growing due to its high productivity rates, which can be further increased through tandem arc techniques. This study evaluates the effect of welding speed on geometric and microstructural characteristics of weldments produced by two wires SAW-T, with two opposite beads each. For this purpose, three structural steel welding joints were manufactured, each using a different welding speed. The weldments' microstructure, bead geometry and hardness distribution were analyzed. Bead geometry suffered negative effect from higher speeds. The welded zones formed consisted mainly of assorted ferrite morphologies, with more acicular ferrite in joints welded under higher welding speeds. Bainite islands were present intragranularly in the heat affected zones, among ferrite microconstituents. Hardness values were slightly raised under higher welding speeds and do not suggest crack susceptibility. None of the weldments produced contained any martensite microconstituents. The highest welding speeds resulted in lack of fusion defects in the weldments, suggesting insufficient heat input and penetration. The joint welded using 1200 mm/min speed showed good geometry and refined microstructure, indicating that this condition is promising as a way to manufacture sturdy steel weldments under high productivity rates.