Influence of prolonged thermal exposure on intergranular fatigue crack growth behavior in alloy 718 at 650 °C

Alloy 718 is a precipitation hardening nickel base superalloy which was developed to provide high creep resistance and high stress rupture at elevated temperatures. The intent of this work is to examine the relationship between microstructural changes during prolonged thermal exposure and the fatigue crack growth performance of alloy 718 in laboratory air environment. The practical significance of this study implies that components made of alloy 718 used in high-temperature service conditions for prolonged periods may gain an intrinsic resistance to intergranular crack propagation due to microstructural changes taking place during the aging time