Coupling of X-ray CT and surface in-situ analysis combined with DIC
method to study low cycle fatigue damage micromechanisms in lost foam
casting A319 alloy
Abstract
An experimental protocol has been set up in order to study the Low Cycle
Fatigue (LCF) damage micromechanisms in a Lost Foam Casting (LFC) A319
alloy at room temperature. The microstructure of the studied material
was characterized by using X-ray Computed Tomography (X-ray CT) prior to
the LCF tests performed with surface in-situ observations, which allow
crack initiation and propagation being tracked in real-time. The
mechanical fields measured by Digital Image Correlation (DIC) method
allowed establishing the relations between strain localizations, damage
evolutions and microstructure while a developed etching method, which
gives a natural texture to the surface, makes DIC feasible to an
acceptable resolution without masking the microstructure. The results
showed that crack initiation is ascribed to strain localizations induced
by large pore and/or the propagation of a previously nucleated crack.
Cracks propagate along hard inclusions but the orientation of hard
inclusions has also an influence on crack path.