Microstructure and mechanical properties of two Api steels for iron ore pipelines

Materials Research

Leonardo Barbosa Godefroid¹  Luiz Cláudio Cândido¹  Rodrigo Vicente Bayão Toffolo¹  Luiz Henrique Soares Barbosa¹ 

[1] ,Universidade Federal de Ouro Preto Rede Temática em Engenharia de Materiais Ouro Preto MG ,Brasil

关键词: API steels;    fracture toughness;    fatigue crack growth;   

DOI  :  10.1590/S1516-14392014005000068

来源: SciELO

【 摘 要 】

This 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.

【 授权许可】

CC BY   
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