Geometry-Dependent Solidification Regimes in Metal Additive Manufacturing

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 transition from a quasistatic point heat source regime to a regime dominated by the quasistatic motion of an equivalent line source. This work provides a simple analytical framework for determining the conditions under wtiich 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 accurately 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 conditions. 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 additrvety manufactured components.