Estudo comparativo de resistência à corrosão entre ligas metálicas ferrosas e não ferrosas

Abstract

Corrosion is a phenomenon that is closely linked to the integrity of the metal and its alloys. This occurs in many ways, one of the main is localized corrosion in the form of pits, object of analysis in this study, that aims to establish a comparison between the cyclic polarization curves of some ferrous and non-ferrous alloys, tested in 0,6M NaCl solution, showing aggressivity the solution exerts on each of the alloys. The materials analyzed in this study were the stainless steel AISI 304, AISI 444, super duplex ASTM A890 / A890 M Grade 6A, carbon steel AISI 1030, commercially pure aluminum, electrolytic copper and zircaloy-4 alloy. Initially the corrosion potentials were measured (Ec) from each alloy through the open circuit potential monitoring. The cyclic potentiodynamic polarization tests on each alloy were conducted, comparing the surface appearance before and after the test by optical micrographs, enabling that differences were observed between each material for resistance to pitting corrosion. It was observed that some alloys do not exhibit passivation such as the case of commercially pure aluminum, and others showed passive regions and well defined hysteresis, being evident that, among the examined alloys, super duplex stainless steel ASTM A890 / A890 M Grade 6A presented best results against the harsh effects of Cl- ions present in the solution, being less susceptible to pitting corrosion.