J. Phys. IV France 125 (2005) 217-219
DOI: 10.1051/jp4:2005125051

H₂SO₄ corrosion of API5L-X52 pipeline steel: Thermal diffusivity and microstructure

G. Peña-Rodríguez^{1, 2}, C. Angeles-Chávez³, O. Flores-Macías³, E. Marín⁴, R.A. Muñoz Hernández¹ and A. Calderón<sup>1

1</sup>  CICATA-IPN, Legaria 694 Colonia Irrigación, 11500 Mexico, DF, Mexico
²  Depto. de Física, U. Francisco de Paula Santander. A.A. 1055, Cúcuta, Colombia
³  Instituto Mexicano del Petróleo, Eje central L.Cardenas 152, 07730 Mexico, DF, Mexico
⁴  F. de Física, U. de la Habana, San Lazaro y L. Vedado 10400, La Habana, Cuba

Abstract
The effect of corrosion by H₂SO₄ on the values of room temperature thermal diffusivity () and the microstructure of API5L-X52 pipeline steel are studied. The samples were exposed for 3, 6, 9, 12 and 15 days in a corrosive solution in an atmosphere with relative humidity of 57.16% in average and at temperature of 23.6 °C. The values were measured by the photoacoustic technique in a heat transmission configuration. Our results show a decrease with the corrosion time (t), with a behavior described by an exponentially decreasing curve. Microestructural study on the samples revealed the appearance of irregular surfaces with corroded grain frontiers, porosity and fractures of micrometer size as a consequence of corrosion, as well as a presence of phases mainly composed by tetra hydrated iron and manganese sulphates. The decreasing evolution of vs t show the activity-passivity behavior in the corrosion process.

© EDP Sciences 2005