Evaluation of the low cycle fatigue failure properties for GTAW weldments of Alloy 617 at 950 °C

This study deals with the high temperature low cycle fatigue failure properties of Alloy 617 base metal and weldments at 950 °C. Comparative study on a wide range of strain controls and its microstructural heterogeneity within base metal and weldments during high temperature fatigue is discussed. Due to the fact that the weldment structures have a degradation impact on the specimens' fatigue lifetime against the base metal. Results are provided for some baseline data about the prediction of the Alloy 617 and its joint service lifetime. The high temperature low cycle fatigue properties of the Alloy 617 and its joint are presented and comparison of other existing literatures are given. Statistical analysis through the strain-life and strain-energy density as a suitable fatigue parameter for characterizing the Alloy 617 base metal and weldments is described. Metallographic studies are presented for understanding the initiation and propagation of fatigue cracks, including effects of sequential brittle oxide layer formation.