Geometry-Dependent Solidification Regimes in Metal Additive Manufacturing

Abstract

Recent modeling and experimental work in additive manufacturing has suggested cross-sectional geometry may play a significant role in the local development of the solidification structure through its influence on the heat source path. This effect has been rationalized as the transi-tion from a quasistatic point heat source regime to a regime dominated by the quasistatic motion of an equiva-lent line source. This work provides a simple analytical framework for determining the conditions under which a system transitions between these regimes. A transient semianalytical heat transfer model is used to examine a wide range of process conditions and material properties. A simple analytical expression is derived and shown to accu-rately predict the transition between solidification regimes over these conditions. The functional form of this expres-sion is then used to help understand the importance of various material properties, process parameters, and geometric factors on the characteristics of the solidification con-ditions. This approach may be used as a simple guideline for optimizing process conditions in response to variations in cross-sectional geometry to produce more consistent microstructural distributions in additively manufactured components.