In order to investigate the fracture mechanism in fatigue of Ni-base superalloy at elevated temperatures, rotating bending fatigue tests were carried out for Inconel 718 at 500°C and 600°C up to 10<SUP>8</SUP> cycles. At both temperatures, fracture occurred from a subsurface of the specimen in long life region, though the origin of fracture was the specimen surface in short life region. Consequently, <I>S</I>-<I>N</I> curves showed a two-step shape in elevated temperature tests. Although a surface crack was observed similar to the result at room temperature even in long life region at elevated temperatures, the surface crack stopped propagating. In this case, interganular cracks were observed at an origin of subsurface fracture. The subsurface damage was initiated at the early stage of fatigue life.
|Translated title of the contribution||Fracture Mechanism in Fatigue of Ni-Base Superalloy Inconel 718 at Elevated Temperatures|
|Number of pages||8|
|Journal||Nihon Kikai Gakkai Ronbunshu, A Hen/Transactions of the Japan Society of Mechanical Engineers, Part A|
|Publication status||Published - 2005|