PSI - Issue 60

Md Rakim et al. / Procedia Structural Integrity 60 (2024) 136–148 Md Rakim et al. / Structural Integrity Procedia 00 (2023) 000 – 000

142

7

1E-8

1E-7

1E-8

1E-9

1E-9

da/dN (m/cycle)

da/dN (m/cycle)

Material: Alloy 617M Weld 27 °C and 5000 hour Ageing Time

Material: Alloy 617M Weld 710 °C and 1000 hour Ageing Time

1E-10

1E-10

10

11

12

13

14

7

8

9

10 11 12 13 14

D K (MPa.m 0.5 )

D K ( MPa.m 0.5 )

Fig.4: ⁄ vs. curves in log-log scale at 27 °C and 5000 hours ageing condition for weld material.

Fig.5: ⁄ vs. curves in log-log scale at 710 °C and 1000 hours ageing condition for weld material.

Table 2. (MPa.m 0.5 ) values at different temperatures and ageing time for base material. Temperature (°C) Ageing Time (hours) 0 1000 5000

20000 6.591 6.249 5.127 4.786

27

8.317 7.762 7.698

7.93 7.08

7.61 6.16 5.62 5.33

650 710 750

6.606

7.17

5.86

Table 3. (MPa.m 0.5 ) values at different temperatures and ageing time for weld material. Temperature (°C) Ageing Time (hours) 0 1000 2000

5000 9.58 6.606

27

9.44 7.97 7.41

10.315

9.67 7.04

650 710 750

7.62 7.09 5.75

6.309 5.888

6.15

6.606 5.63 Figures 6 to 9 shows variation of value of base and weld metals in terms of temperature and ageing time. As a general trend, value has been decreasing with increasing temperature for a given ageing time. Similarly, for a given test temperature, the value has been decreasing with increasing ageing time. The same kind of trend has also been observed for welded metal. Nevertheless, the reduction in value has been faster for welded metal than the base metal as shown in Figs. 7 and 9, due to the presence of residual stress at elevated temperatures.