Issue 36

I. Camagic et alii, Frattura ed Integrità Strutturale, 36 (2016) 1-7; DOI: 10.3221/IGF-ESIS.36.01 6 da/dN, m/cycle 0 100 200 300 400 500 600 0 -10 10 -9 10 -8 10 -7 10 -6 Temperature, 0 C ▫  new PM ◦  exploited PM Figure 6 : Fatigue crack growth rate, da/dN, vs. temperature for specimens with notches in PM. da/dN, m/cycle 0 100 200 300 400 500 600 10 -10 10 -9 10 -8 10 -7 10 -6 Temperature, 0 C Figure 7 : Fatigue crack growth rate, da/dN, vs. temperature for specimens with notches in WM. da/dN, m/cycle 0 100 200 300 400 500 600 10 -10 10 -9 10 -8 10 -7 10 -6 Temperature, 0 C ▫  new HAZ ◦  exploited HAZ Figure 8 : Fatigue crack growth rate, da/dN, vs. temperature for specimens with notches in HAZ. D ISCUSSION alues obtained for PM fatigue threshold,  K th , are in the range 5.8 MPa  m (20  C) to 5.1 MPa  m (540  C), Tab. 5. Additional reduction for 10-15% is recorded due to exploition period 10-15%, since values for fatigue threshold,  K th , are in that case in the range 5.2 MPa  m (20  C) to 4.7 MPa  m (540  C), Tab. 6. Similar effects are noticed in HAZ, where values of fatigue threshold,  K th , obtained for new material, are in the range 5.5 MPa  m (20  C) to 4.8 MPa  m (540  C), i.e. from 4.6 MPa  m (20  C) to 4.2 MPa  m (540  C) for exploited material, Tabs. 8 and 9. V