Influência do aporte térmico sobre a morfologia da austenita e na quantidade das fases em chapas soldadas de aço inoxidável duplex SAF2205

Abstract

The duplex stainless steels have a microstructure wherein the composition of ferrite and austenite volume fraction is near 50%. These are used in the manufacture of various components and products, mainly for applications in the oil industry. In these applications often welding processes are used. To mitigate this process changes due to the material properties a suitable choice of the welding parameters is needed. In this context, the aim of this study was to evaluate the effect of heat input on the morphology of the austenite and the amount of the phases, and identify which welding condition provides a balance of volume fractions of ferrite and austenite. The materials analyzed are stainless steel duplex sheet SAF2205, welded by GMAW welding process, the ESAB, varying the heat input in 0.5, 1.0 and 1.5 kJ / mm. After welding, the sheets were cut, prepared for metallographic examination of the morphology formed and austenite phases for quantification. The results showed the presence of alotriomórfica austenite grain boundaries, the austenite Widmanstätten and intragranular austenite. It was found that the heat input less altered the balance of ferrite and austenite phases was 1.5 kJ / mm, concluding that one should use it when the goal is to keep the volume ratio of the phases in duplex steel SAF2205.