Efeito da energia de soldagem na resistência à corrosão do metal de solda no revestimento de aço inoxidável Duplex

Abstract

Duplex Stainless Steel present in its microstructure ferrite and austenite phases the balance of these phases in the same value (50%) provides to these materials an excellent corrosion resistance combined with good mechanical properties. However, studies with multipass welding have been rather superficial, indicating a motivation to work achievements in the area. This work has as objective to analyze the influence of the heat input, changing the welding current or speed on the corrosion resistance, in the coatings. Steel plates ASTM A516 Gr. 60 (150x100x13 mm) welded with coated electrode AWS E2209-17 of 4,0 mm to deposition of weld overlay in two layers, with overlap between 30 to 50%. Multipass welding had been realized with three levels (15, 20 e 24 kJ/cm), varying welding current and speed. Cyclic polarization test were carried out to evaluate the corrosion resistance of the welds. Three electrode-cell with a platinum plate as counter electrode and a Ag/AgCl electrode as a reference electrode had been carried. Samples were taken with cuts in longitudinal direction to evaluate the first and last weld bead of the second layer. According to electrochemical tests one can say that the conditions C4P and C4U (15kJcm) presented greater pitting corrosion resistance and the conditions C5P and C3P (24kJcm) presented poorer pitting corrosion resistance.