718 superalloy forging simulation: A way to improve process and material potentialities

Abstract

In a forged condition, 718 superalloy is commonly used to manufacture some aircraft engine turbine parts severely loaded in service. The mechanical behavior of these parts depends on both thermo-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 process variability during the procedure which enable to get time, cost and quality savings.