Solidification cracking is one of the most prevalent defects occurs in casting, welding, and additive manufacturing processes. One of the required parameters that is challenging to specify in the analysis of solidification cracking by most of the common criteria is the bridging liquid fraction (fl,brid), which refers to the liquid fraction below which solidification cracking susceptibility (SCS) reduces. A model was developed based on the interfacial energies and solidification microstructure size to calculate fl,brid across different alloy compositions and, in turn, accurately predict the solidification cracking behavior. The higher sensitivity of grain boundaries to cracking compared to dendritic boundaries inside the grain can be easily shown with the model. The model also accurately predicts the composition with the highest cracking susceptibility (CSCSmax) in various binary aluminium alloy systems. Furthermore, based on this model, changes in CSCSmax under different processing conditions (i.e., thermal gradient and solidification rate) were accurately predicted by accounting for changes in microstructure size and possible back diffusion occurrence. The model was verified with independent experimental reports and original laser welding experiments.

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