In-situ microscopic analysis of ferritic ductile iron during tensile loading: Relation between matrix heterogeneities and damage mechanisms

FERNANDINO, DIEGO O.; BOERI, ROBERTO E.

FATIGUE & FRACTURE OF ENGINEERING MATERIALS & STRUCTURES (PRINT)

WILEY-BLACKWELL PUBLISHING, INC

Año: 2019 vol. 42 p. 2220 - 2231

8756-758X

An in‐situ microscopic analysis of the damage mechanisms of ferritic ductileiron under uniaxial tensile testing is carried out in this work. The experimentalmethodology combines specialized metallography techniques, in‐situ opticalmicroscopy observation during loading, and digital image correlation analysisto obtain the strain values at the microscopic level. The results show that thecrack initiation is preferentially located at matrix‐nodule interface and ferriticgrain boundaries. The propagation of multiple cracks across the internodularligaments that later coalesce into a single dominant crack is responsible forthe final fracture. Noticeably, despite the heterogeneous nature of the Last‐to‐Freeze zones, the cracks propagate avoiding these microsegregated areas.The results provide new insights for the better understanding of the influenceof ferritic ductile iron heterogeneities on the fracture process for quasistaticuniaxial loading.