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.11: Variation of J IC with ageing time at different temperature conditions for weld material

Fig.12: Variation of J IC with temperature at different ageing times for weld material

Fig. 13: Variation of J IC with ageing time at different temperature conditions for forged material

Fig. 14: Variation of J IC with temperature in different ageing times for forged material

Through experimental investigations, it has also been observed that under ideal conditions for higher temperature regions, the J-R curve shows dissimilarity compared to room temperature. For high-temperature region, there has been a stable tearing as indicated in the load-LLD curve. Moreover, stable tearing happens at higher values of J -integral as the crack growth mechanism is resisted by blunting. This has also been evidenced from specimens through visual observation after experimental tests as they contain a very large stretch zone. From tensile test data, it has been identified that at temperature ranges from 580 to 800 °C, dynamic strain ageing comes into play in this alloy that acts as the driving potential for strain hardening. Formation of dynamic strain ageing (DSA) promotes an increased strength in material but with a decrease in elongation as the interaction between solute atoms with the dislocation movement happens at the time of plastic deformation [V. Shankar et al. (2017)]. The present investigation has been carried out for temperature ranges at 650 °C, 710 °C and 750 °C, DSA can be expected to cause considerable material hardening that contributes to the reduction of fracture toughness ( J IC ) which happened to be true.