| Volume 1. This section describes a detailed experimental and statistical analysis carried out to determine the risks and benefits of implementing a damage tolerance based lifing procedure for the General Electric J85-CAN40 engine. This is a 'post-facto' investigation, using components of this engine retired by the Canadian Forces and the data available regarding these used parts. The emphasis is on the 5th stage compressor disc, which is one of the most crack-prone components of this engine.;A number of procedures have been demonstrated by which the "safe line" and the "safe inspection interval" for this component can be calculated reliably. The possibility of improving the existing lifing procedure through a damage tolerance approach, and the limitations of the damage tolerance approach are discussed on the basis of experimental observations and information available from field experience.;Also described in this volume are the results of a study carried out to determine the feasibility of rejuvenating retired J85-CAN40 turbine wheels by a re-heat treatment procedure.;Volume 2. In this volume, a study has been made to microstructure-environment interactions during elevated temperature (650(DEGREES)C) crack growth in Inconel 718, which is used as a turbine disc material for the J85-CAN15 and F-404 engines. Static and cyclic loading conditions (R = 0.05, f = 0.1 Hz) have been studied using a tapered double cantilever beam (constant-K) fracture mechanics speciment. Four microstructures with a wide range of grain sizes, precipitate particle sizes and grain boundary morphologies were studied. It has been attempted to relate observed differences in crack growth behaviour to possible differences in the micromechanisms of deformation and fracture. Particularly, it has been emphasized that the sensitivity of this alloy to environmental embrittlement is enhanced by a fine grain size and a hyperfine (gamma)'' distribution. Heat treatments which lead to a serrated grain boundary morphology have been shown to improve crack growth resistance.;The feasibility of applying a damage tolerance based lifing technique to Inconel 718 turbine components has been discussed. |
