Rotating bending fatigue tests were carried out for Inconel 718 at room temperature to investigate the growth characteristics of a small crack. It was found that : (1) The crack initiated at the grain boundary and then propagated as a transgranular crack. (2) When the stress level was higher than the fatigue limit, the fatigue life was mainly controlled by the growth life of a crack smaller than 1mm. (3) The fatigue limit was a limiting stress for the crack propagation. (4) At low stress levels (σ<SUB>a</SUB>/σ<SUB>0.2</SUB><0.5, σ<SUB>a</SUB> : stress amplitude, σ<SUB>0.2</SUB> : 0.2% proof stress), the crack growth rate was determined by the stress intensity factor range ΔK ; and at high stress levels (σ<SUB>a</SUB>/σ<SUB>0.2</SUB>>0.6), it was determined by the small crack growth law.
|Translated title of the contribution||Characteristics of Small Crack Growth in a Nickel-Base Superalloy|
|Number of pages||5|
|Journal||Nihon Kikai Gakkai Ronbunshu, A Hen/Transactions of the Japan Society of Mechanical Engineers, Part A|
|Publication status||Published - Jul 25 1997|