Heat and fluid flow in additive manufacturing-Part I: Modeling of powder bed fusion

Structure and properties of components made by the powder bed fusion (PBF) additive manufacturing (AM) are often optimized by trial and error. This procedure is expensive, time consuming and does not provide any assurance of optimizing product quality. A recourse is to build, test and utilize a numerical model of the process that can estimate the most important metallurgical variables from the processing conditions and alloy properties. Here we develop and test a three-dimensional, transient, heat transfer and fluid flow model to calculate temperature and velocity fields, build shape and size, cooling rates and the solidification parameters during PBF process. This model considers temperature dependent properties of the powder bed considering powder and shielding gas properties, packing efficiency and powder size. A rapid numerical solution algorithm is developed and tested to calculate the metallurgical variables for large components fabricated with multiple layers and hatches rapidly. Part I of this article describes the model, solution methodology, powder bed properties, and model validation. The applications of the model for four commonly used alloys are presented in part II.