Chemistry-based Solidification Model

FLOW-3D CAST v5.1 solidification model

FLOW-3D CAST v5.1’s new, state-of-the art, chemistry-based solidification model advances the industry into the next frontier of casting simulation – giving users the ability to predict the strength and integrity of cast parts while reducing scrap and still meeting product safety and performance requirements.

Solidification model capabilities

The new solidification model computes the solidification path and material properties, including latent heat, thermal conductivity, heat capacity, density, viscosity, etc. from the evolution of temperature and chemistry considering nucleation, segregation, and cooling conditions.

The solidification model predicts the microstructure evolution based on composition and cooling conditions, such as secondary dendrite arm sapcing (SDAS) and grain size. It also predicts macro-segregation due to diffusion and advection. The empirical relationships between the mechanical properties and microstructure are based on experimental measurements. With unique and powerful microstructure and mechanical property prediction capabilities, the new solidification model lays the foundation for other models, such as dimensionless Niyama criterion for microporosity prediction.

The solidification microstructure and porosity defects are the main factors affecting the mechanical properties of a casting. In turn, the local microstructure is determined by the chemical composition of the alloy, solidification rate, and chemical non-homogeneities due to segregation of the alloying elements. Using the new solidification model, process designers can determine the effect of various process parameters and alloy compositions on the mechanical properties to optimize the performance of their castings to produce the highest quality, safest products possible.

Solidification of A356

Solidification of A206

MICROSTRUCTURE OUTPUT

  • Secondary dendrite arm spacing (SDAS)
  • Grain size

MECHANICAL PROPERTY OUTPUT

  • Ultimate tensile strength (UTS)
  • Elongation
  • Quality index
  • Yield strength for heat treated properties

DEFECT INDICATORS

  • Dimensionless Niyama criterion
  • Microporosity

Full and simplified chemistry-based solidification models

The solidification model includes both full and simplified models, which gives users greater control over their simulation workflow. The full model takes chemical composition and phase change into account as the melt solidifies, while the simplified model offers faster runtimes and does not require as much memory as the full model. A restart simulation based on the full model can start from a simplified model and vice versa. This provides complete flexibility for using the appropriate model for different types of simulations as well as different stages of the simulation.

We recommend that users employ the simplified model as much as possible, due to its obvious advantages of using less resources. We recommend that users employ the full model for cases where macro-segregation is significant. For thermal die cycling simulations, the simplified model is enforced by the software since a full analysis is not needed in these modeling scenarios.

For some thin-walled castings, macro-segregation based on diffusion and advection is not significant. In these castings, the solidification path is almost the same throughout and it is not necessary to track the composition and phase evolution during solidification for each individual computational cell. For these types of scenarios, we recommend that the user employs the simplified solidification model to reach their solution faster.

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