In design of components for aircraft industry with special emphasize on lifetime it is necessary to take into account four essential influence factors:

- load spectrum (amplitude, frequency) - design (shape) - material - manufacturing process

The determining factors for component design are the local stress which can be influenced by an adequate design and the fatigue strength of the material, which can be affected by a suitable selection of the material and the manufacturing process. In general the load spectrum of a component is entirely defined by service conditions and cannot be modified. Mainly in manufacturing of forged components both parameters material and thermo-mechanical processing play a decisive role. Forging processes applying different strain rates lead to different microstructural characteristics of the material. Furthermore, the mechanical properties of the forged component, e.g. fatigue strength, depend markedly on microstructural features like grain size and its distribution. In this work the microstructure and the fatigue properties of Inconel 718 forged on three different aggregates (hydraulic press, hammer and screw press) is investigated. The results are consequently compared to those obtained from Inconel 718 VAR material. For both raw material as well as forgings a standard heat treatment is carried out. Tensile- and –rotating bending tests with smooth specimens at R=-1 are performed at room temperature. The microstructure is investigated in a light microscope. Based on fatigue test results an empirical law is formulated to describe the fatigue strength of forged components. This law is used to derive a simulation model which allows a determination of the fatigue strength and life time already in the state of design. Such an early assessment of life time by simulation methods will yield a significant reduction of development cycle time and cost.