The HAZ transformations in the welding of duplex steels

Abstract

The increasing use of duplex steels in plant and welded constructions has resulted in the formulation of quality criteria for such steels and the joints welded in them. These cover the areas of macro–and microstructures, mechanical properties, and resistance to corrosion. The criteria rely, primarily, on the value of the ratio of the ferrite to austenite, the existence of carbides on grain boundaries, and on the precipitations of intermetallic phases in both the weld and the heat affected zone. To meet these criteria, it is necessary to properly control the sequence of the phase changes, and of the precipitation processes which are decisively affected by the character of the welding cycle of the steel.