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In a forged condition, 71 8 superalloy is commonly used to manufacture some aircraft engine turbine parts severely loaded in service. The mechanical behavior of these parts depends on both thenno-mechanical conditions during flights and microstructural characteristics of the alloy.As the microstructure is controlled by forging process, numerical models are developed to predict relevant microstructural data such as grain characteristics which are related to the processing parameters. Based on experimental studies, simulation tools allow to optimize a process range insuring its stability and the part quality in accordance with the required specifications.Subsequently, these models will allow to describe the mechanical resistance of the forged part correlated with the flight thermo-mechanical data. For example, an empirical law was established to link grain size, temperature, strain range and low cycle fatigue (LCF) resistance. It has been introduced into a lifing software and validated by comparing experimentation and simulation. Thus, forging simulation models are implemented to take into account the grocess variability during the procedure which enable to get time, cost and quality savings.

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Abstract. In order to reduce costs and increase the operating temperatures in aero-turboengines and space propulsion systems, net-shape or near net-shape production processes have been developed for static parts through HIPing (Hot Isostatic Pressing) of nickel base superalloys prealloyed powders. The presented results hereafter are related to the manufacturing processes and the mechanical properties (tensile, creep and LCF) characterisation. The effects of net shape surfaces and of surface conditioning have been investigated too. Examples of actual parts (CFM56 turbine casing and Vulcain rocket engine gas generator) illustrate the presentation. This study has confirmed the interest of this production route and future potential for development.