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

Abstract

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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

“…No subsurface pore was found around initiation site D and no crack was observed to propagate to this area from other pores. Thus, hard inclusions may have acted as initiation sites at or around site D as hard inclusions are indeed observed to act as crack initiation site due to strain localizations in previous study by using 3D in-situ analysis 21,22 .…”

“…A previous study in the laboratory 21,22 shows that the strain localizations around large pores are responsible for crack initiation. In addition to large pores, hard inclusions may have also acted as individual crack initiation site in the studied material, such as 2 nd crack initiation site for Specimen 1 (Fig.…”

“…The material used in this study was extracted from an A319 (7.85 wt.% Si, 0.30 wt.% Fe, 3.05 wt.% Cu, 0.19 wt.% Mn, 0.28 wt.% Mg) prototype cylinder head, which was manufactured using LFC process, from the most critical area, i.e. the fire deck 22 (Fig. 1a).…”

“…Pores are assumed to be the most probable crack initiation sites in HCF 12,14,17,24,25 and in LCF as demonstrated in a previous study in the laboratory 21,22 .They were thus characterized in the bulk of specimens using Lab-CT to identify possible crack initiation areas, i.e. ROI.…”

“…This analysis is made even more difficult in LCF as failure often results from multicracking rather than from a single crack 18 . Recently, 3D in-situ analysis with X-ray Computed Tomography (X-ray CT) has been used to study the damage mechanisms of A319 alloy in LCF by the authors 21,22 . It allows following crack initiation and propagation in the bulk of the studied material and highlights the influence of the strain localizations due to the pores on crack initiation.…”