PSI - Issue 22

L. Sena et al. / Procedia Structural Integrity 22 (2019) 171–180 179 Lígia T. Silva, Bruno Mendes, Carlos Oliveira, Cristi Reis, Paula Silv ; José Silva / Fi s International Symposium on Risk and Safety of Complex Structures and Components (2019), Porto, Portugal

(a) (b) Fig. 7. SEM images of the surface of the Gray Cast Iron samples after immersion in 3% phosphoric acid, over a period of 21,600s. (a) 323.15K; (b) 373.15K.

(a) (b) Fig. 8. SEM images of Gray Cast Iron samples surface after 3% phosphoric acid immersion test, over a period of 43,200 s. (a) 323.15 K; (b) 373.15 K. 4. Conclusion The present work indicated that FC-250 Cast Iron, when submitted to immersion tests in H 3 PO 4 , has its structure compromised. This phenomenon was identified by the fact that the surface corrosion is of the intergranular type, which causes loss of mechanical properties and can be called corrosion on fracturing stress. The higher percentage of acid results in higher mass losses, the temperature reacts analogously and in longer times the loss is sustained. Solution concentration, temperature and duration are all important factors in corrosion studies. When analyzing a relevant number of bibliographies in metallic materials under similar conditions, no relevant variations were observed from the obtained results.