ASSESSMENT OF LIFETIME CALCULATION OF FORGED IN718 AEROSPACE COMPONENTS BASED ON A MULIT-PARAMETRIC MICROSTRUCTURAL EVALUATION

摘要

The goal of linking a fatigue life approach with different forging parameters enforces the consideration of the main process dependent influence factors, e.g. effective strain, effective strain rate, grain size etc. In case of forged parts, the thermo-mechanical process allows a specific adjustment of microstructural features like grain size or fraction of precipitates, etc. Linking the specimen lifetime results to these microstructural features, a new design parameter for forged parts has been achieved. This forecasting parameter can be used in the preliminary design stage to optimize forgings with regard to lifetime. For this reason it is possible to get minimized weight and maximized lifetime in the final part and therefore optimize the total life cycle costs. The main objective of the research was the development of a method to predetermine the lifetime of forged alloy 718 aircraft parts.