PSI - Issue 47

Andrea Zanichelli et al. / Procedia Structural Integrity 47 (2023) 37–42 Zanichelli et al. / Structural Integrity Procedia 00 (2023) 000–000

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3.2. Fracture testing Both PM and GOM specimens are tested to determine fracture toughness, according to the Modified Two Parameter Model (Carpinteri et al. (2017); Vantadori et al. (2021), (2022), (2023)) and RILEM Recommendations (RILEM Technical Committee, 50-FMC (1985); RILEM Technical Committee, 89-FMT (1990)). The specimens, whose sizes are equal to 60 30 300 mm × × , contain a notch with a depth equal to 20 mm in the lower part of the middle cross-section, and are subjected to three-point bending (span equal to 240 mm ). Such tests are performed under Crack Mouth Opening Displacement (CMOD) control with a rate of 0.15 mm h . 3.3. Microstructural analysis The X-ray diffraction is performed on both PM and GOM powders by using a Bruker D2 PHASER diffractometer, whereas a Scanning Electron Microscope JEOL 6400, equipped with an Oxford EDS, is used for SEM observations. 4. Results The mean value of the flexural strength, computed for both PM and GOM specimens, is reported in Fig. 1 together with the corresponding standard deviation. It can be observed that only a small increase of the mean flexural strength (equal to about 4% ) is achieved for the GOM specimens with respect to that for the PM ones.

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1.0 FLEXURAL STRENGTH [MPa] PM

GOM

SPECIMENS TYPE

Fig. 1. Mean value and standard deviation of the flexural strength, for both the PM and GOM specimens.

The mean value of the compressive strength, computed for both PM and GOM specimens, is reported in Fig. 2 together with the corresponding standard deviation. It can be observed that only a small increase of the compressive strength (equal to about 3% ) is achieved for the GOM specimens with respect to that for the PM ones.