Session: 17-01-01: Research Posters

Paper Number: 148931

148931 - Multi-Scale Modeling of Particle Size Distribution in Metal Additive Manufacturing - Effect on Structure and Porosity 

Selective Laser Melting (SLM) is an additive manufacturing process that uses a high-power-density laser to selectively melt and fuse metallic particles layer by layer based on a 3D model. This process enables the production of complex and customized parts with reduced material waste and lead time. SLM is beneficial for applications that require parts with intricate geometries, lightweight structures, and excellent mechanical properties.

Selective Laser Melting (SLM) has several challenges that can affect the process's quality, reliability, and efficiency. Some common problems in SLM include defects such as pores, cracks, keyholes, and inhomogeneities due to several factors, such as laser power, scanning speed, powder quality, and process parameters. These defects can significantly affect the final part's mechanical properties, surface finish, and functionality. Also, SLM can cause high residual stresses in the final part due to the rapid heating and cooling rates and the localized melting and solidification process. These stresses can cause warping, distortion, and cracking in the part, reducing its dimensional accuracy and stability.

The particle size distribution is a pivotal factor that can profoundly influence the outcome of the Selective Laser Melting (SLM) process. The size of the powder particles plays a crucial role in determining the packing density, surface area, melting temperature, and thermal conductivity of the metal powder bed. These factors, in turn, can significantly impact the final part's microstructure and mechanical properties, underscoring the importance of the particle size distribution in SLM.

Studies have shown that a narrow and uniform particle size distribution can produce a more homogeneous microstructure with fewer defects, higher density, and improved mechanical properties. Moreover, the particle size distribution can affect the laser absorption and energy transfer during the melting process. Therefore, optimizing the particle size distribution is critical to achieving high-quality SLM parts with desired properties. This can be done by selecting the appropriate powder size range, sieving or classifying the powder, and controlling the powder morphology and chemistry.

The present work employs advanced simulation techniques to investigate the sintering process of the metal powder bed using LAMMPS and ANSYS. The simulation model not only studies the effect of various factors, such as particle size distribution, heating and cooling rates, and structural changes within the powder bed, but also provides a visual representation of the formation of voids and keyhole defects that may arise during the fusion process. The results of this comprehensive analysis offer valuable insights into the structural changes and porosity development mechanisms in Metal Additive Manufacturing parts, enriching our understanding of the SLM process.

Presenting Author: Nikhil Ingle North Carolina Agricultural and Technical State University

Presenting Author Biography: Nikhil Ingle is PhD candidate at The Joint School of Nano-science and Nano-engineering affiliated to the North Carolina Agricultural and Technical State University. His research areas include Metal additive manufacturing, Molecular Dynamics Simulations, Nano-materials modelling and Computational Fluid Dynamics.

Authors:

Nikhil Ingle North Carolina Agricultural and Technical State University
Rauf Shah North Carolina Agricultural and Technical State University
Ram Mohan North Carolina Agricultural and Technical State University