Avaliação de fluxos para soldagem SAW twin arc em altas velocidades de juntas em ângulo para fabricação de vigas metálicas

Abstract

The industrial demand for steel structures requires techniques and processes with a high level of mechanization due to tight lead times, consistent quality levels and the increasing shortage of skilled workers in the Brazilian market. The continuous application of more productive manufacturing processes depends on efficient joining techniques, such as submerged arc welding (SAW). This method has become widely used in longitudinal welds for making structural components, such as truss structures, piles and steel beams. Three important variables determine the behavior of mechanical properties, size and metallurgical changes of joints welded by SAW: the wire, the flux and the welding parameters. Consumable manufacturers offer a variety of combinations between welding wire and flux, defined based on their physical and chemical characteristics, as well as their contribution to the mechanical properties of the joint. The present study compares four welding fluxes using Twin Arc welding at high speeds in T joints for fabricating ASTM A36 structural steel beams. The tests examined the behavior of the fluxes using qualitative factors, such as the linearity of the weld bead obtained, slag detachability, presence of secondary slag and surface discontinuities such as undercut, porosity and hammering of the weld bead; and dimensional factors, such as the angular weld sections and weld legs, through macrographic analysis of optimized weld beads for the four fluxes at each welding speed. The work also proposes a cost-benefit analysis of national and imported consumables for internal market.