PSI - Issue 23

Libor Nohal et al. / Procedia Structural Integrity 23 (2019) 227–232 Author name / Structural Integrity Procedia 00 (2019) 000 – 000

231

5

macrocracks

phase3

phase1

phase2

isolated / oriented cavities

microcracks

Fig. 4. Histogram of AE hits during the entire creep test (period hits = 600 sec).

Then, AEE begin to localize near the lower waveguide of channel B in the zone of the maximum tensile stress (AREA1 in Fig. 6). Amplitudes of AE events in this region have higher values than in the rest of events. For more accurate AE signal, it is convenient to focus only on AEE from AREA1 and search other connections in creep process. In order to find a connection between creep damage and AE response, a detailed metallographic evaluation of the damaged specimen was performed, including fractographic documentation of both fracture surfaces. However, this section is not included in this article and will be published in another paper.

cumulative AE hit energy

Fig. 5. AE hits energy distribution of D18 specimen during the entire creep test.