An Automated Fully-Computational Framework to Construct Printability Maps for Additively Manufactured Metal Alloys

TL;DR

This paper introduces a fully computational framework that constructs printability maps for metal alloys in additive manufacturing, reducing reliance on costly experiments and enabling high-throughput alloy process optimization.

Contribution

The work presents a novel integrated computational approach combining CALPHAD, reduced-order, and thermal models to predict defect-prone regions in additive manufacturing alloys.

Findings

Validated printability maps against experimental data for five alloys.

Extended framework to NiTi alloys with different compositions.

Demonstrated use of maps to guide defect-free additive manufacturing.

Abstract

In additive manufacturing, the optimal processing conditions need to be determined to fabricate porosity-free parts. For this purpose, the design space for an arbitrary alloy needs to be scoped and analyzed to identify the areas of defects for different laser power-scan speed combinations and can be visualized using a printability map. Constructing printability maps is typically a costly process due to the involvement of experiments, which restricts their application in high-throughput product design. To reduce the cost and effort of constructing printability maps, a fully computational framework is introduced in this work. The framework combines CALPHAD models and a reduced-order model to predict material properties. THen, an analytical thermal model, known as the Eagar-Tsai model, utilizes some of these materials' properties to calculate the melt pool geometry during the AM processes. In the end, printability maps are constructed using material properties, melt pool dimensions, and commonly used criteria for lack of fusion, balling, and keyholing defects. To validate the framework and its general application to laser powder-bed fusion alloys, five common additive manufacturing alloys are analyzed. Furthermore, NiTi-based alloys at three different compositions are evaluated to show the further extension of the framework to alloy systems at different compositions. The defect regions in these printability maps are validated with corresponding experimental observations to compare and benchmark the defect criteria and find the optimal criterion set with the maximum accuracy for each unique material composition. Furthermore, printability maps for NiTi that are obtained from our framework are used in conjunction with process maps resulting from a multi-model framework to guide the fabrication of defect-free additive manufactured parts with tailorable properties and performance.