Session: 02-01-01: 7th Annual Conference-Wide Symposium on Additive Manufacturing: Metals I

Paper Number: 96912

96912 - A Physics-Based Model of Laser Powder Bed Fusion of NiTi Shape Memory Alloy: Laser Single Track and Melt Pool Dimension Prediction 

NiTi shape memory alloys (SMAs) are currently the most researched SMA material in Additive Manufacturing(AM). The SMA material’s two key features are Shape Memory Effect(SME) and superelasticity(SE). After being heated, the shape-memory effect restores the material to its primary shape, while superelasticity refers to material recovery from a substantial degree of inelastic deformation​​​​​​. NiTi Shape memory alloys are increasingly being employed in a variety of applications, with continuous research into practical processing methods.

The laser powder bed fusion(LPBF) manufacturing method is exhibiting increasing attention to fabricating SMA materials due to the high flexibility of controllable process parameters. Physics-based modeling is a more cost- and time-effective approach for optimizing LPBF process parameters. This technique is crucial in the early stages of LPBF optimization since it aids in a better understanding of the problem by considering the physical processes involved. The major phenomena included in the LPBF approach are heat transfer, fluid dynamics, vaporization, solidification, volume change, and phase transition. Finite element method (FEM) approaches are deployed to offer an intelligent fabrication path and minimize the high time and cost expenses of experimentations.  In this work, a thermal model is developed to predict the melt pool size and shape during NiTi's LPBF. Macroscale physics framework via COMSOL Multiphysics is used to build a thermal model for NiTi LPBF processing. To this end, a single-track scanning of laser over the NiTi substrate with Gaussian power density has been modeled.

The thermal/melt pool modeling of a single laser pass on NiTi substrate is employed. The model is calibrated for the thermal parameters such as the conductive and convective coefficient and emissivity coefficients. The calibration is performed through the comparison of experimental temperature measurements via optical microscopy and in-situ thermal imaging and the numerical modeling results.

A 3D transient modeling of additive manufacturing focused on a single laser pass treatment on NiTi plate using COMSOL software is built up. The model considers the heat transfer through conduction, convection, and radiation and the mobile heat source with the Gaussian distribution. The model is calibrated by setting the thermal conductivity, emissivity, and convective coefficients for the NiTi plate.

A good agreement is observed between the 3D transient model and experimental thermal profiles. This model can open the opportunities for easier exploration of different process parameters for NiTi additive manufacturing, which in turn can offer a better perception of final material properties dependent on the initial process parameters.

Presenting Author: Hossein Abedi University of Toledo

Presenting Author Biography: Hossein Abedi is a Ph.D. student at the Mechanical, Industrial, Manufacturing Engineering Department at the University of Toledo.

Authors:

Hossein Abedi University of Toledo
Reza Javan University of Toledo
Mohammad Reza Nematollahi University of Toledo
Keyvan Safaei University of Toledo
Anwar Al-Gamal University of Toledo
Mohammad Elahinia University of Toledo
Ala Qattawi The University of Toledo