PSI - Issue 60

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

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Md Rakim et al. / Structural Integrity Procedia 00 (2023) 000 – 000

precipitation and inter- metallic γ' -phase particles happen inside the grain that remains stable. For this reason, material hardness does not change considerably. For weld samples, at 27 °C, the values have been nearly constant for all aged durations. Through tensile experiments, material strength increases significantly at room temperature from as-received to ageing conditions. For the as-received condition, the yield strength value is 310 MPa, whereas for 1000 hours of ageing condition, yield strength increases significantly to 480 MPa. After increasing the ageing time, further yield strength also increases. Hence, when ageing time increases at 27 °C, the ∆K TH value does not decrease, it has been almost constant. But at higher temperature domain (650-750 °C) along with all aged conditions, there has been a gradual decrease in the value of . The reason is the microstructural disintegration effect on the mechanical properties after prolonged ageing conditions and the reduction in fracture energy is attributed to the coarsening and precipitation redistribution. Also, the value of shows a small scatter at particular aged conditions at elevated temperature (650-750 °C) domain but that value is much lower in comparison with 27 °C as the yield strength of the material decreases due to thermal activation resulting in higher dislocation movement.

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Alloy 617M Base Alloy 617M Weld

Alloy 617M Base Alloy 617M Weld

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6 D KTH ( MPam 0.5 ) 8

7 D KTH ( MPam 0.5 ) 8

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Temperature (ºC)

Temperature (ºC) Fig.10: Comparison of with temperature for base and weld material at as-received condition

Fig.11: Comparison of with temperature for base and weld material at 5000 hours aged condition

Through experimental investigation, for both the forms of alloy 617M i.e., base and weld materials, the value of shows a significant difference at room temperature conditions. The observation suggests that for weld material, the value is much higher compared to the base material for as-received as well as for 5000 hours aged durations which are shown in Figs. 10 and 11 respectively. The reason behind this explanation is the fact that the yield strength and ultimate strength for weld is much more than the base material. The comparison analysis shows that for weld materials at a temperature of 710 °C or more, the value slightly decreases for as-received conditions than the base metal. From the curves, it has also been observed that with an increase in temperature, the slope of decreases more in the case of weld material compared to the base material.