Mechanical properties of duplex steel welded joints in large-size constructions

Abstract

Thick panels measuring 9.5, 14.5, and 18.5 mm made of UNS S31803 duplex steel were tested for welding with the use of powder wire. The target task consisted in determination of the impact of the welding process with an increased root gap on the mechanical properties of joints, as compared with the properties achieved by welding with a 6-mm threshold distance in compliance with the provisions set out in the DNV regulations. The results demonstrated that the root gap tolerance could be extended; furthermore, they proved that wide-clearance welding – production of welded joints through double cordon welding with a single operator in the vertical position (PF) – is possible without the need to apply border hardening in the case of duplex steel, provided that the weld groove geometry has a root gap within 6–10 mm, from the point of view of compliance of welded joints with requirements concerning mechanical properties.