Influência do efeito da temperatura de preaquecimento, do tipo de corrente e do gás de proteção na soldagem de chapas finas de aço inoxidável duplex uns s31803

Abstract

The necessity of materials that combine high corrosion resistance and good mechanical properties make the duplex stainless steel UNS S31803 widely used in corrosion environments, such as petrochemical industry, marine and others. Their weldability necessary for mounting and repairing equipment, still have many technological difficulties, such as precipitation of deleterious phases and alteration of ferrite/austenite balance. It becomes more complex when is difficult to control the heat flux. This work has the purpose to evaluate samples of duplex stainless steel UNS S31803 of thinness, subjected to GTAW weld process without filler metal with preheating in order to enable better control of the fusion zone. Experiments were conducted varying current (convectional and pulsed) and temperature of the preheating stage. Test of double loop electrochemical potentiodynamic reactivation was also performed in order to study the corrosion resistance in this region. The balance of ferrite/austenite was accounted and the microstructural characterization was evaluated by optical microscopy and scanning electron microscopy (MEV). It was concluded that changing the types of current, the shielding gas and the temperature of preheating influenced the microstructural balance and corrosion resistant.