Session: 17-15-01: Society-Wide Micro/Nano Poster Forum

Paper Number: 99652

99652 - Prediction of Porosity and Its Mechanisms in Metal Additive Manufacturing 

Selective Laser Melting (SLM) or sometimes called direct metal laser sintering (DMLS), is an up-and-coming additive manufacturing technique that uses a laser as the power source and is specially developed for 3D Printing metal alloys. In the SLM process, a high-​power-density laser is used to melt and fuse metallic particles. The laser aims at points in space defined by a three-dimensional (3D) model, binding the material together through the sintering process to create a solid structure. The advancement in Selective Laser Melting is significant since it can create custom property parts, reduce material usage and design freedom, and quickly manufacture complex components. All these factors make it a promising technology for manufacturing complex components and technology of the future.   

The high energy density of laser generates various unwanted structural defects such as keyholes and porosity, which results in crack formation & distortion, and subsequent reduction in mechanical strength of the components. The process-induced variations have been a long-standing problem in the additive manufacturing (AM) industry. Many studies have been done to optimize the Laser parameters, but the proper understanding of the mechanism of crack formation due to keyholes and porosity is still limited.

The present work in broad aims to understand the SLM process and study its process parameter that affects the final part’s mechanical properties. To attain this we simulate the relevant physical configurations of the SLM process and identify process parameters and the effect of metal powder variation. A representative model based on Molecular Dynamics (MD) is developed to explore the sintering mechanism of metal powders. Open-source code LAMMPS (Large-scale Atomic/Molecular Massively Parallel Simulator) has been used to develop a working model to emulate a powder bed consisting of metal particles. The melting phenomenon is simulated by first defining the regions of melt due to laser heating. Then heating layer by layer of the metal particle bed, which is cooled subsequently. In addition to simulating the metal powder bed melting and particle fusion, the particle size distribution and geometry effects, structural variations in the powder bed are visualized, and voids/keyholes defect formation is captured.

Preliminary results were shown to capture void formations during the cooling of melt zones and the development of grain structure was also captured. The results from this study will be able to better predict the onset mechanism of porosity and crack formation in Metal 3D printed parts. Hence by understanding this phenomenon, better quality Metal 3D Printed parts can be manufactured.

Presenting Author: Nikhil Ingle NC A&T State University

Presenting Author Biography: Nikhil Ingle is a Graduate Research Assistant at the Joint School of Nanoscience and Nanoengineering in Greensboro, NC. His research interest focuses on Computational Nanoengineering. Using MD simulations he is trying to capture the physics of Metal additive manufacturing so that better quality parts can be manufactured using 3D printing devoid of defects.

Authors:

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