Session: 03-03-01: Annual Congress-Wide Symposium on Additive Manufacturing I

Paper Number: 166886

Defect Mapping and Process Optimization of Lpbf Ss316l via X-Ray Computed Tomography 

Stainless Steel 316L (SS316L) is a widely used material due to its excellent corrosion resistance and high-temperature application, making it essential for energy, aerospace, biomedical, and industrial purposes. Laser Powder Bed Fusion (LPBF) has emerged as a key additive manufacturing (AM) technique for producing SS316L components. Currently, significant research is going on to improve the mechanical properties and optimize the microstructures of LPBF-fabricated SS316L compared to their traditionally fabricated counterparts. While extensive research has been conducted on LPBF-processed SS316L, most studies focus on a narrow range of process parameters that yield the highest part densities, typically following recommendations from printer manufacturers. However, this limited exploration of process conditions restricts a more basic understanding of the material’s behavior under varied manufacturing settings.

Process parameters in LPBF, particularly laser power and scan velocity, play a crucial role in determining both build rate and energy density, ultimately affecting the material’s microstructure, porosity, and mechanical performance. Optimizing these parameters is critical for applications that require a balance between production efficiency and part quality. For instance, some industrial applications may prioritize higher build rates to reduce production time while maintaining an acceptable density level. Additionally, not all applications require the highest possible density, as maximizing density can lead to increased costs and longer processing times without significant benefits for certain use cases.

To bridge this knowledge gap, we conducted a systematic analysis of LPBF-processed SS316L samples across a broad range of power and velocity settings to assess density variations and develop a comprehensive defect distribution map. A total of 24 samples were fabricated using a TruPrint 3000 printer, with variations in laser power and scan speed designed to cover a wide spectrum of processing conditions. Hatch spacing and layer thickness were kept constant, and neither up-skin nor down-skin strategies were employed. After fabrication, each sample was segmented into quarters and analyzed using X-ray computed tomography (XCT) to characterize internal porosity and defect structures. XCT provides a high-resolution, non-destructive method for evaluating the volumetric distribution of defects, allowing for a detailed correlation between process parameters and defect formation.

The defect distribution map generated from this study serves as a valuable resource for understanding the trade-offs between process efficiency, part density, and defect formation. By expanding the explored parameter space beyond traditional high-density processing windows, this work contributes to the broader scientific understanding of LPBF-processed SS316L and provides practical insights for optimizing production strategies in additive manufacturing.

Presenting Author: Nadia Kouraytem Utah State University

Presenting Author Biography: I am an assistant professor at the Department of Mechanical and Aerospace Engineering at Utah State University and director of the "Mechanical Evaluation and Testing of Additively Layered 3D Structures Lab"- METAL 3D Structures Lab. My main area of research is on evaluating the process-structure-property relationships in metal additive manufacturing, colloquially known as 3D printing, using advanced experimental techniques.

Authors:

Ryan Higdon Utah State University
Tasrif Ul Anwar Utah State University
Nadia Kouraytem Utah State University