Executive Summary : | Fatigue failure is a major cause of failure in mechanical components, often resulting from the nucleation and growth of surface or subsurface cracks. Cracks often nucleate near matrix and inclusion interfaces and propagate, depending on the local microstructure, mechanical loads, and component geometry. Two situations can arise when determining crack propagation analysis: detecting cracks during periodic inspection or determining the cycle a component can withstand without complete rupture. The role of microstructural features on crack propagation is crucial for determining service life. Gas turbines, widely used in the aerospace and power industry, are made of nickel-based superalloys, with critical zones such as blade disk attachment area and key slots. These disks can contain micropores and carbide particles, and grain size can significantly affect crack growth rate. This study investigates the influence of grain size, carbides, and porosity on fatigue crack growth using crystal plasticity finite element modelling. The stress intensity factor of the propagating crack is estimated using crystal plasticity and elastoplastic fracture mechanics within the finite element framework. The propagation path is determined using cohesive zone modelling and compared with the analytical approach. The proposed methodology helps understand crack propagation behavior at the microlevel, improving life predictions and developing an effective strategy to increase the service life of gas turbine disks. |