Multiphysical simulation of hot cracking in Laser-Based Powder Bed Fusion

Abstract

This study extends an existing comprehensive computational framework to gain insight on hot cracking in the simulation of laser-based additive manufacturing via powder bed fusion. A novel approach to predict hot crack susceptibility based on vapor cavitation, building on a conceptual model akin to the Rappaz-Drezet-Gremaud criterion is introduced. Unlike conventional practices involving ex-situ evaluation of a criterion, the proposed model emerges implicitly from the underlying multiphysical modeling framework. The model exhibits sensitivity to variations in both material attributes (e.g., alloy composition) and processing conditions (e.g., laser beam shape or scanning strategy). Furthermore, non-equilibrium solidification is incorporated in the underlying Mass-of-Fluid framework, and a model for multi-layer printing is introduced to extend the length and time scale, enabling the derivation of detailed thermal histories on near-part-scale level. Consequently, the framework proves pivotal in optimizing process parameters, transcending the limitations inherent in conventional single melt track computational experiments.