Session: Research Posters

Paper Number: 120279

120279 - Effect of Particle Size Distribution on Voids in Metal Additive Manufacturing 

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 particularly useful 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 quality, reliability, and efficiency of the process. Some of the 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 mechanical properties, surface finish, and functionality of the final part. Also, SLM can cause high residual stresses in the final part due to the rapid heating and cooling resulting in 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 critical factor that can significantly affect the outcome of the Selective Laser Melting (SLM) process. The size of the powder particles can influence the packing density, surface area, melting temperature, and thermal conductivity of the metal powder bed, which in turn can affect the microstructure and mechanical properties of the final part.

Studies have shown that a narrow and uniform particle size distribution can result in a more homogeneous microstructure with fewer defects, higher density, and improved mechanical properties. Moreover, the particle size distribution can affect the laser energy 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 paper simulates and investigates the sintering process of the metal powder bed using a layer-by-layer heating and cooling approach. Using the LAMMPS (Large-scale Atomic/Molecular Massively Parallel Simulator) open-source code, a Molecular Dynamics (MD) model is created to examine the sintering mechanism of metal powders (with random size distribution). The effect of various factors such as particle size distribution, heating and cooling rates, and structural changes within the powder bed are studied. Additionally, the simulations model, analyze and visualize the formation of voids and keyhole defects that may arise during the fusion process. The results provide insights and the mechanisms of porosity and crack development in Metal Additive Manufacturing parts. Complete details and discussions will be presented in the technical paper.

Presenting Author: Nikhil Ingle NC A&T State University

Presenting Author Biography: Nikhil Ingle is the Ph.D. 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 modeling, and Computational Fluid Dynamics.

Authors:

Nikhil Ingle NC A&T State University
Ram Mohan NC A&T State University