Application of Synchrotron Radiation-Computed Tomography In-Situ Observations and Digital Volume Correlation to Study Low-Cycle Fatigue Damage Micromechanisms in Lost Foam Casting A319 Alloy

The synchrotron radiation-computed tomography (SR-CT) and digital volume correlation (DVC) methods were used to investigate the damage micromechanisms of lost foam casting (LFC) A319 alloy in low-cycle fatigue (LCF). LCF tests with SR-CT in-situ observations allow visualizing the damage evolution process in the bulk. DVC measures the mechanical fields and, thus, allows establishing the relations between crack initiation and propagation, mechanical fields, and microstructure. Cracks initiate at and propagate along hard inclusions due to strain localizations. The damage process, i.e., crack initiation and propagation, can be considered as a series of failure events of hard inclusions under strain localizations. The pores' size, shape, location, and number were observed to have an influence on crack initiation, while the interconnected hard inclusion networks guarantee the continuous failure events of hard inclusions and, thus, provide crack propagation paths.