Abstract

QUIROZ, Rosdely; ROSALES, Adalberto  and  BARON, Evaristo. Efecto de la perlita en aceros bandeados sobre la resistencia a la corrosión por co₂. Rev. LatinAm. Metal. Mater. [online]. 2009, vol.29, n.2, pp.84-92. ISSN 0255-6952.

The effect of the microstructure on CO₂ corrosion resistance of two API 5L B X/42 ferritic-pearlitic steel was investigated. Weight lost and Linear Polarization Resistance tests were carried out in NaCl 3,5 wt% solution saturated with CO₂, at pH 3,5 and 45 ± 1oC. Samples were evaluated by means of optical and scanning electron microscopy coupled to EDS, for chemical analysis. The distance between pearlite bands and the separation of carbide lamellae within the pearlite colonies were found to be the principal microestructural difference. These features had a significant effect on the CO₂ corrosion process. Initially, FeCO₃ deposits were located at pearlite colonies, on both materials. On the other hand, the distance between pearlite bands and the interlamellar spacing within the pearlite colonies affected the dissolution of the ferrite phase between bands. When pearlite bands and Fe₃C lamellas were closer to each other, they became more defined and efficient cathodic regions. This produced a greater dissolution rate of the ferrite bands in this steel and, as a consequence, an increase in the overall corrosion rate of the steel.

Keywords : CO₂ Corrosion; Ferrite - Pearlite banded steel; Cementite.