Integrated Modelling and Simulation of the Additive Manufacturing and Heat Treatment Process Chain

Abstract

Additive manufacturing of metal parts is widely used for different alloys and different types of application. During building of the parts, local heating of the powder generates a small melt pool with high thermal gradients followed by rapid solidification. Already solidified material is re-melted and affected by heating when layers are added. The thermal history of the moving heat source and the layer building of the part have a high influence on the formed microstructure, the risk of porosities and evolution of cracks. High stresses and permanent deformations develop during the building process, which lead to large deformations when e.g. the base plate is removed. Heat treatment of the parts is often used to reduce the stress level and to minimize the deformations. This paper presents an integrated modelling and simulation approach, where results from the additive manufacturing process are used as initial conditions for the subsequent heat treatment process. An integrated simulation approach has been developed and implemented as a dedicated solution to simulate the sequence of the additive manufacturing process and subsequent heat treatment steps. To get reasonable calculation times multiscale methods have been tested to perform virtual experiments, where the influence of different scanning strategies have been evaluated to optimize temperature distributions and the influence on mechanical performance. A unified creep model is used to describe the mechanical behavior of the material to ensure a consistent description through the large temperature interval and the different levels of time and strain rates.