PSI - Issue 60

Md Rakim et al. / Procedia Structural Integrity 60 (2024) 298–310 Md Rakim et al. / Structural Integrity Procedia 00 (2023) 000 – 000

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Fig. 15: Comparison of J IC with different temperatures at as-received conditions for base, weld and forged materials.

Fig. 16: Comparison of J IC with different temperatures at 5000 hours ageing condition for base, weld and forged materials.

Within the experimental framework scattering, there has been significant difference in fracture toughness ( J IC ) value that is observed in all forms of alloy 617M i.e., base, weld and forged materials. From Figs. 15 and 16, it has been observed that for weld material fracture toughness value is least compared to other forms of alloy 617M. The reason behind this explanation has been the fact that yield along with ultimate strength for this material shows much more compared to other materials along with comparably lower ultimate strength to yield strength ratio. For that reason, weld material shows reduced plastic deformation compared to base and forged metal. So, from Figs. 15 and 16, it has been explained that weld material shows a lower fracture toughness ( J IC ) at both as-received and 5000 hours aged conditions. From the comparison studies, it has been also observed that for weld materials at a temperature of 750 °C the J IC value abruptly decreases for as-received as well as 5000 hours aged condition. This finding explains weld material resembles more temperature sensitivity than other forms of alloy 617M. From these two curves, it has been observed that out of these three-alloy forged alloy fracture toughness value is much higher for as-received as well as for 5000 hours aged conditions. In accordance with experimental output and analysis, the below conclusions are stated regarding variation in fracture toughness at 27 °C, 650 °C, 710 °C and 750 °C with ageing time durations up to 20000 hours for the three forms of the alloy 617M namely base, weld and forged material samples within elastic-plastic fracture mechanics framework: 1. Through observations, it has been revealed that alloy 617M follows a gradually decreasing trend of elastic plastic fracture toughness ( J IC ) when the temperature is increased. However, results show that J IC decreases with an increase in temperature beyond a particular range of temperature. 5. Conclusion