13th International Conference on Fracture June 16–21, 2013, Beijing, China surfaces and the geometrical defect located in the fracture-to-burnish transition zone can be seen. The initial porosities can be seen in the bulk of the specimen in black. These voids are aligned along the martensite alignments (interfaces ferrite-martensite) [1]. Coalescence sheets can be seen in figure 5e-f where needle voids growing from the cut-edge, i.e. fracture zone surface, coalesce with the internal needle voids corresponding to the decohesion of ferrite-martensite interfaces. These needle voids then coalesce with the burnish zone though narrow areas known as void sheets. (a) (b) (c) (d) (e) (f) Figure 5: L-T views of 3D volumes of the steel sheet plane of reconstructed laminography data of damage evolution from a cut-edge at CMODs. (a) The scanned zone (b) material at delivery state (700x350x504 µm3); (c) CMOD = 1 mm, (700x350x294 µm3); (d) CMOD = 2 mm, (700x350x294 µm3); (e) CMOD = 3 mm, (700x350x294 µm3); (f) CMOD = 4 mm, (700x300x260 µm3). Figure 6 shows the shape of needle voids grown from the fracture zone surface and in the bulk. These needle voids consist with the decohesion of ferrite-martensite interfaces (i.e. the flow lines) characterized in Ref [1]. -6-
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