2026 Annual International Solid Freeform Fabrication Symposium (SFF Symp 2026): In-Situ Monitoring and Parameter Optimization
Program Organizers: David Leigh, University of Texas at Austin
Wednesday 8:00 AM
August 5, 2026
Room: Guadalupe
Location: AT&T Center
8:00 AM
Observation of Balling Defect Formation Mechanism in Laser Melting Using Synchroton X-Ray Radiography: Tharun Reddy1; Zane Taylor1; Debomita Basu2; Rajib Halder2; Samuel Clark3; Kamel Fezzaa3; Benjamin Gould3; Tao Sun4; Bryan Webler2; Anthony Rollett2; Leora Dresselhaus-Marais1; 1Stanford University; 2Carnegie Mellon University; 3Argonne National Laboratory,; 4Northwestern University
The productivity of metal additive manufacturing technologies strongly depends on laser power and scan velocity. However, high-power and high-scan velocity (high-PV) conditions often lead to balling defects, where material accumulates non-uniformly along melt tracks. These elevated regions and melt track discontinuities degrade part quality and can cause build failures. To investigate the origin of balling, we employed synchrotron high-speed X-ray radiography to directly observe its formation during laser melting of stainless steel. We find that vapor depression morphology and solidification velocity govern the periodicity and size of these defects. Our results reveal distinct melt pool dynamics at high-PV conditions that differ significantly from previously studied regimes. These quantitative insights into an underexplored region of the PV space will inform strategies to mitigate balling and support scalability efforts.
8:20 AM
Wetting Characteristics of Molten Titanium Particles Under Substrate Preheating in LPBF: Sato Yuji1; Norio Yoshida1; Yorihiro Yamashita2; Takahisa Shobu3; Masahiro Tsukamoto1; 1University of Osaka; 2University of Fukui; 3Japan Atomic Energy Agency
Titanium exhibits poor wettability during LPBF owing to its high surface tension, leading to unstable melt behavior such as balling and spatter generation. In this study, the wetting characteristics of molten titanium were investigated by in-situ synchrotron X-ray imaging using a single Ti particle under vacuum conditions. The substrate temperature was varied from 25 °C to 500 °C. As a result, the contact angle decreased significantly from 148° to 32° with increasing temperature, demonstrating a remarkable improvement in wettability. Enhanced wetting promoted stable spreading of the molten particle and improved interfacial contact with the substrate. These findings indicate that substrate temperature strongly governs the wetting characteristics of molten titanium and contributes to stabilization of the LPBF process.
8:40 AM
In Situ Synchrotron Radiography of Bubble Dynamics in Tungsten During Laser Powder Bed Fusion: Cesar Diaz-Caraveo1; Zane Taylor1; Tharun Reddy1; Yunhui Chen2; Paul Wallace1; Alexander Rack2; Steven Van Petegem3; Leora Dresselhaus-Marais1; 1Stanford University; 2European Synchrotron Radiation Facility; 3Paul Scherrer Institute
Laser powder bed fusion processing of tungsten presents an important opportunity for net-shape parts in extreme temperature environments like nuclear fusion. However, tungsten LPBF suffers from multiple cracking mechanisms, and it is greatly affected by impurity concentrations. Formation of nanopores has been reported extensively in the literature, but much is unknown about its dynamics. Here, we report our in-situ X-ray synchrotron radiography of bubble dynamics in single-track experiments. We observe bubbles coming mainly from the surface and vapor depression vicinity regions without the presence of a keyhole. Ex-situ characterization through XCT provides the final size and positions of the bubbles, and bubble cross-sectioning provides clues into their formation mechanisms as oxide precipitates are observed in their solidified walls. Our study demonstrates the first in-situ bubble dynamics observation in tungsten, a phenomenon with great relevance for the performance of LPBF tungsten-processed parts and their future applications.
9:00 AM
Processing-Structure-Property Relationship of Aheadd CP1 Aluminum Alloy Manufactured Via LPBF: Edgar Reyes1; 1UTEP
Laser powder bed fusion of high-performance aluminum alloys requires precise control of the printing process parameters to achieve consistent density, microstructure, and functional performance. This study investigates Constellium Aheadd CP1 aluminum alloy produced using different parameter sets such as laser power, scan speed, hatch spacing, and volumetric energy density. Initial characterization focuses on correlating processing conditions with density, Vickers microhardness, chemical uniformity, thermal conductivity, and microstructural features observed on sectioned build specimens. This initial characterization relates the printing process parameters in terms of composition, internal defects, melt pool morphology, porosity-related scatter, and process-dependent property response on the manufactured samples. These results provide a foundation for physically informed processing-structure-property relationships and future machine learning models for CP1 additive manufacturing optimization.
9:20 AM
Melt Pool Behavior, Microstructure and Mechanical Properties of Modulated Laser Powder Bed Fusion Processed Ti6Al4V: Sivaji Karna1; Sun Can2; Venkata Satya Surya Amaranth Karra1; Lang Yuan2; Hector Siller1; 1University Of North Texas; 2University of South Carolina
In powder bed fusion-laser beam/metal (PBF-LB/M) processing, microstructure control is critical for tailoring mechanical properties and improving component performance. This study investigates the effect of scan speed on melt pool formation under continuous-wave (CW) and laser-modulated processing conditions. At lower scan speeds, CW processing resulted in keyhole-mode melt pool behavior. By adjusting laser modulation parameters, particularly frequency, duty cycle, effective heat input was controlled, enabling transition from keyhole to conduction-mode melting. Cubic samples with high density (>99.9%) were obtained with optimized process parameters. Electron backscatter diffraction analysis revealed that laser modulation reduced the columnar prior β grain width compared with CW laser processing and promoted preferential α variant formation. Tensile testing was performed on horizontally oriented specimens, and results were correlated with the microstructure. Overall, this study demonstrates that laser modulation provides an effective strategy for controlling the microstructure of PBF-LB/M printed Ti6Al4V without altering alloy chemistry.
9:40 AM Break
10:00 AM
Additive Manufacturing of Titanium-Zirconium-Molybdenum Alloy Using Electron Beam Powder Bed Fusion: Shadman Tahsin Nabil1; Kurtis Watanabe1; Cesar Terrazas1; Bryant Kaines2; Nicholas Barta2; Michael Brand2; James Carney1; Francisco Medina1; 1University of Texas at El Paso; 2Los Alamos National Laboratory
Titanium-Zirconium-Molybdenum (TZM) is a high-performance refractory molybdenum alloy frequently used in aerospace, including rocket nozzles, high-temperature structural components, and radiation shielding. This material has excellent creep resistance and superior strength at elevated temperatures. Despite its favorable properties, fabricating TZM with conventional manufacturing methods remains challenging due to its inherent brittleness and limited room-temperature workability. This research focuses on developing process parameters for TZM in Electron Beam Powder Bed Fusion (EB-PBF) using Design of Experiments (DOE). EB-PBF is well-suited for refractory materials as parts can be built at elevated temperatures through preheating, enabling hot-working conditions. A systematic DOE was employed to optimize key process parameters. Relative density was measured using Archimedes' principle, helium pycnometry, and optical microscopy to validate fabrication quality. Results demonstrate the viability of EB-PBF for high-performance TZM alloy fabrication and establish a foundation for process optimization.
10:20 AM
Additive Manufacturing of NdFeB magnet via DED: Challenges, Optimization and Performance: Puskar Pathak1; Kripa Adhikari1; Daniel Schulze1; Venkat Selvamanickam1; 1University of Houston, Advanced Manufacturing Institute
Among the wide range of materials processed using additive manufacturing (AM), there remains strong interest in rare-earth magnetic materials, particularly NdFeB magnets. Conventional fabrication methods such as sintering and pressing dominate production but offer limited design flexibility and require multiple post-processing steps. This study investigates the printability of NdFeB magnets using laser engineered net shaping (LENS), a directed energy deposition (DED) technique. A comprehensive design of experiments was conducted to evaluate process parameters and fabricate bulk components. Internal defects, including cracks and porosity, were characterized using micro-computed tomography (CT) and correlated with processing conditions. Although near-net-shape fabrication was achieved, the as-built parts exhibited poor magnetic performance due to limited formation of the hard-magnetic Nd2Fe14B phase. To address this, flash annealing was applied to as-fabricated parts, improving the magnetic properties. A mechanistic relationship between processing, microstructure, and magnetic performance was established, highlighting the challenges and opportunities of processing NdFeB with AM.
10:40 AM
Sheet-Based Additive Manufacturing of Titanium Alloys Using Laser Pulse Integration of Sheets (LAPIS): Jonathan Singham1; Changquan Lai1; 1Nanyang Technological University
Ti-6Al-4V (Ti64) is widely used in aerospace and biomedical applications due to its high specific strength, corrosion resistance, and biocompatibility. Additive manufacturing (AM) is particularly attractive for Ti64 fabrication because it enables the production of complex geometries, lightweight structures, and customised implants while reducing material waste associated with subtractive processing. However, conventional AM processes are powder-based, imposing limitations related to cost, safety, and stringent environmental control. This work explores the fabrication of Ti alloys via a new sheet-based AM approach, Laser Pulse Integration of Sheets (LAPIS). LAPIS replaces powder feedstock with metal sheets and enables the exploration of Ti alloy AM processing under both ambient and controlled atmospheres.The role of processing atmosphere is investigated by comparing builds produced under ambient and argon conditions, including the effect of oxygen and defect formation. The feasibility of varying the processing atmosphere during printing to introduce spatially controlled microstructural heterogeneity is explored.
11:00 AM
Influence of Porosity on Impact Toughness of Stainless Steel 316L Fabricated via Laser Powder Bed Fusion for Nuclear Applications: Rebecca Herrera1; Lizbeth Licerio1; Ben Hroblak2; Justin Miner2; Sneha Prabha Narra2; James Carney1; Francisco Medina1; 1W.M. Keck Center for 3D Innovation; 2Mechanical Engineering Department, Carnegie Mellon University
Limited impact toughness data has hindered the adoption of Laser Powder Bed Fusion (PBF-LB/M) Stainless Steel 316L components within nuclear regulatory frameworks, where toughness is critical for irradiation performance. This study investigates the process-structure-property relationships of impact toughness in PBF-LB/M fabricated Stainless Steel 316L, focusing on the impact of the process parameters on the as-built microstructure and subsequent heat treatments on impact toughness. An experiment was conducted varying the scanning velocity to generate differences in porosity and microstructure. Additionally, three distinct heat treatments were conducted to isolate the impact of microstructure from porosity: (i) a treatment that balances between residual stress relief and retention of the as-built microstructure, (ii) a treatment designed to promote precipitation of σ, χ, and carbide phases, and (iii) a treatment intended to dissolve secondary phases. Impact toughness was evaluated using Charpy V-notch testing to quantify the effects of processing and heat treatment on material performance.