Powder Bed Fusion

The Additive Manufacturing Module is an Add-on Module in Thermo-Calc that is primarily designed for modeling the powder bed fusion process in Additive Manufacturing. 

The Additive Manufacturing Module allows users to calculate any alloy. This was done by giving special focus to having a unified treatment of alloy dependent material properties and process parameters when solving the multiphysics problem of a moving heat source that melts and solidifies metal powder. The multiphysics simulation involves thermal conduction, fluid flow, evaporation-, radiation- and convective- heat loss. 

The alloy dependent physical properties such as specific heat, density, thermal conductivity, viscosity, and surface tension of liquid are all calculated from evaporation temperature down to room temperature using the extended SCHEIL calculator and are automatically transferred for use in the Additive Manufacturing Module. By simulating materials properties in the software, users are able to make calculations for any alloy. 

The module has 3 calculation types: Steady-State, Transient, and Transient with heat-source from Steady-State. Steady-State solves the stationary problem for the melt pool given the Process Parameters*. Transient and Transient with heat-source from Steady-State solves the time dependent problem for a single or multi-layer process for given Process Parameters*.

*Process Parameters that Can Be Changed for the Simulation

Scanning speed, layer thickness, scanning pattern, hatch spacing, powder fill time, heat source (including power, absorptivity and heat distribution), chamber pressure and base plate temperature

Evaluation of the following is possible depending on calculation type:

The Additive Manufacturing Module offers several ways to visualize results, including Printability Maps, also known as Process Maps. Printability maps allow users to plot the likelihood of three possible defects that occur during additive manufacturing – keyholing, lack of fusion, and balling.

These defects occur based on the speed and power used during the AM process, so printability maps allow you to reduce the risks of these defects by showing the speed and power settings that are optimal (the white area in the image below), allowing you to calibrate your system to avoid these issues.

The AM Module offers several calculation types, including a Batch Calculation that allows users to input power and scan speed data from a file, such as a spreadsheet. This calculation type also allows users to include experimental melt pool dimensions, if they have them, so that they can compare experimental results to calculated results. This is done using a plot type called a Parity Plot, as shown in the image below.

The Additive Manufacturing Module makes it easy to set up simulations related to the powder bed fusion process for additive manufacturing by offering an intuitive workflow and templates for setting up the simulations. The software also allows users to save their alloys directly in the calculator, so you can easily access them later, saving time and ensuring consistency in your work. The software ships with several common alloys used in additive manufacturing so users can begin making simulations immediately. 

The Additive Manufacturing Module allows users to predict the microstructure of an alloy by seamlessly coupling with both the Diffusion Module (DICTRA) and Precipitation Module (TC-PRISMA). In this coupling, the probe data generated from an AM calculation can be used as input for diffusion and precipitation calculations.

Additionally, thermal gradient and solidification rates generated in the AM Module can be overlaid over Columnar to Equiaxed Transition (CET) plots generated in the General Model Library, allowing users to evaluate if the solidified microstructure corresponds to columnar or equiaxed, given the solidification conditions in the melt pool. This is all done within the Thermo-Calc platform without the need for importing or exporting data. Relevant add-on licenses are required for the Diffusion Module (DICTRA) and the Precipitation Module (TC-PRISMA). 

Most of the functionality in the Additive Manufacturing Module is also available in TC-Python, our Python-based API. This API allows users to easily perform simulations over a large range or process parameters and to produce printability maps for when defects like lack-of-fusion, keyholing, and balling will occur.

The actual integration needs to be programmed by the customer using Python.

Results from the Additive Manufacturing Module can be exported in the Exodus file format, which is a common file format used with finite element analysis programs. Once exported, the files can be retrieved and used to further process and analyze simulation results in an external software. 

For compatibility with the Additive Manufacturing Module, a database needs the following properties added in addition to the thermodynamics: surface tension for liquid, viscosity for liquid, thermal conductivity, molar volume, and a complete gas description.

The Additive Manufacturing Module is currently available with the following databases, starting with the version listed below: