COMPARISON BETWEEN LINEAR AND NON-LINEAR FRACTURE MECHANICS ANALYSIS OF EXPERIMENTAL DATA FOR THE DUCTILE SUPERALLOY HAYNES 230

Vith increasing use of renewable energy sources, an industrial us turbine is often a competitive solution to balance the power 'rid. However, life robustness approaches for gas turbine corn9nents operating under increasingly cyclic conditions, is a chalmging task. Ductile superalloys, as Haynes 230, are often used n stationary gas turbine hot parts such as combustors. The main cad for such components is due to non -homogeneous thermal xpansion within or between parts. As the material is ductile Jere is considerable redistribution of stresses and strains due to nelastic deformations during the crack initiation phase. There ore, the subsequent crack growth occurs through a material with :gnificant residual stresses and strains. In this work, fatigue ack propagation experiments, including the initiation phase, ave been performed on a single edge notched specimen under train controlled conditions. The test results are compared to -acture mechanics analyses using the linear AK and the non near AJ approaches, and an attempt to quantify the difference 2 terms of a life prediction is made. For the tested notched gemetry, material and strain ranges, the difference in the results using AKeff or ATeff are larger than the scatter seen when fitting the model to the experimental data. The largest differences can be found for short crack lengths, when the cyclic plastic work is the largest. The AJ approach clearly shows better agreement with the experimental results in this regime.