Issue 43

N. Montinaro et alii, Frattura ed Integrità Strutturale, 43 (2018) 231-240; DOI: 10.3221/IGF-ESIS.43.18 234 The samples Two reference samples in Inconel 600 have been used with artificial flaws. Laser drilling was used to create holes in the samples, with different diameters ( ϕ ) and depths ( d ) below the surface. The two samples geometries are shown in Fig. 3. Sample 1 is a plate with holes below the thickness on faces A and B (see Fig. 3a), drilled at different distances from the edge; sample 2 has a raised portion, representing the first deposited layer above the substrate, where holes were drilled (see Fig. 3b). After laser drilling, dimensions and depths of the holes were measured. It is observed that the laser drilling implemented in this work determines a variation in diameter along the hole drilling depth (see Tab. 3 for an indication of initial and final diameters of the drilled hole defects). Flaw sizes are also reported in Tab. 3. Figure 3 : The two geometries of Inconel 600 samples: sample 1 with 4 through holes (a) and sample 2 with 3 holes, among which one superficial and one blind (b) . Thermocamera Brand FLIR Model X6540sc Sensor Focal Plane array, InSb Resolution (h×v) 640×512 pixels Spectral response 1.5-5 μm Lens (hfov × vfov) MW 25 mm F/2.0 (21.74°×17.46°) Thermal Resolution (NETD) 20 mK Table 2 : Specification of the IR camera. Defect/sample ϕ Diameter back/front side (Mean) [µm] d Depth[mm] 1/1 700/250 (470) 1.3 Sample 1 2/1 660/190 (420) 0.6 3/1 800/490 (640) 0.88 4/1 440/850 (640) 0.9 1/2 (490) 0 Sample 2 2/2 blind/360 0.1 3/2 70/330 (200) 0.3 Table 3 : Dimensions and depths of laser drilling holes. (a) (b)