Brittle fracture-based experimental methodology for microstructure analysis

Abstract

Metallographic techniques are crucial tools for establishing the connection between observed mechanical behaviour of metals and the underlying mechanisms in their microstructures. In this work, we propose a methodology that minimizes deformation and/or modification of the microstructure during specimen preparation, and provides a 3D representation of the deformed micromorphology. This methodology involves opening up fractured (tensile test) specimens under the ductile-to-brittle transition temperature of metals to yield two parts in a brittle manner. The occurrence of brittle fracture is validated by analyzing the detailed, unaltered microstructure from SEM characterization and surface profilometry mapping of sets of two parts. It is found that this technique yields additional valuable information regarding the size and morphology of deformed grains or nucleation mechanisms of ductile damage. Experiments with a number of different steels show that the methodology can be applied to sheet of different formability.