# Three-dimensional non-isothermal phase-field modeling of microstructure evolution during selective laser sintering

## TL;DR

This paper introduces a comprehensive 3D non-isothermal phase-field model for simulating microstructure evolution during selective laser sintering, capturing complex phenomena like melting, pore formation, and grain migration, validated through stainless steel 316L experiments.

## Contribution

It presents a novel thermodynamically consistent non-isothermal phase-field model with efficient grain tracking for SLS, enabling detailed microstructure prediction and analysis.

## Key findings

- Identified effects of laser power and scanning speed on microstructure.
- Validated porosity evolution follows first-order kinetics.
- Linked densification to specific energy input during SLS.

## Abstract

Predicting the microstructure during selective laser sintering (SLS) is of great interests, which can compliment the current time and cost expensive trial-and-error principle with an efficient computational design tool. However, it still remains a great challenge to simulate the microstructure evolution during SLS due to the complex underlying physical phenomena. In this work, we present a three-dimensional finite element phase-field simulation of the SLS single scan, and revealed the process-microstructure relation. We use a thermodynamically consistent non-isothermal phase-field model including various physics (i.e. partial melting, pore structure evolution, diffusion, grain boundary migration, and coupled heat transfer), and interaction of powder bed and laser power absorption. The initial powder bed is generated by the discrete element method. Moreover, we present in the manuscript a novel algorithm analogy to minimum coloring problem and managed to simulate a system of 200 grains with grain tracking using as low as 8 non-conserved order parameters. The developed model is shown to capture interesting phenomena which are not accessible to the conventional isothermal model. Specifically, applying the model to SLS of the stainless steel 316L powder, we identify the influences of laser power and scanning speed on microstructural indicators, including the porosity, surface morphology, temperature profile, grain geometry, and densification. We further validate the first-order kinetics during the porosity evolution, and demonstrate the applicability of the developed model in predicting the linkage of densification factor to the specific energy input during SLS.