Godefroid, Leonardo BarbosaCândido, Luiz CláudioToffolo, Rodrigo Vicente BayãoBarbosa, Luiz Henrique Soares2015-05-222015-05-222014CODEFROID, L. B. et al. Microstructure and mechanical properties of two API steels for iron ore pipelines. Materials Research, São Carlos, v. 17, p. 114-120, 2014. Disponível em: <http://www.scielo.br/pdf/mr/2014nahead/aop_matres_223713.pdf>. Acesso em: 09 abr. 2015.1516-1439http://www.repositorio.ufop.br/handle/123456789/5467This research compares the mechanical behavior of two API steels (X60 and X70) used in the longest pipeline in the world for the conveyance of iron ore. Tensile tests, Charpy impact tests, CTOD tests and fatigue crack growth tests are performed at ambient temperature. Metallographic examination showed a banded microstructure consisting of polygonal ferrite and pearlite in both steels, with smaller grain size and the presence of a small quantity of bainite in the X70 steel. All the mechanical tests revealed a ductile behavior for the two steels. The X70 steel is preferable for the pipeline project, due its better mechanical resistance, with no significant loss of fracture toughness and fatigue resistance. Its performance could be even better, if an appropriate combination of thermomechanical processing parameters were able to produce a microstructure with minor amount of pearlite, where acicular ferrite/bainite are present.en-USAPI steelsFracture toughnessFatigue crack growthArtigo publicado em periodicoAutorização concedida ao Repositório Institucional da UFOP pela Materials Research em 25/10/2013 com as seguintes condições: disponível sob Licença Creative Commons que permite copiar, distribuir e transmitir o trabalho desde que sejam citados o autor e o licenciante. Não permite o uso para fins comerciais nem a adaptação.http://dx.doi.org/10.1590/S1516-14392014005000068