Fracture resistance of flash welded and laser welded butt joints in a microalloyed HSLA steel

Abstract

High-strength, low-alloy (HSLA) steels are widely used in the automotive and oil industries due to their good mechanical properties and weldability. The selection of the welding process depends on several factors, including the quality of the weld bead and the production capacity. The knowledge of the mechanical performance of the welded joint is essential to ensure structural reliability. In the present work, butt joints were produced from 5 mm thick plates of a microalloyed HSLA steel by flash welding and by laser welding processes, the latter using two different heat input conditions. The microsctructure and hardness of the weld beads were evaluated. The fracture toughness of the welded joints was assessed by means of CTOD tests. The higher heat input laser welded joint presented critical CTOD comparable to that of the flash welded joint, whereas the lower heat input martensitic-bainitic laser welded joint tended to a brittle behavior.