Additive Manufacturing: Beyond on the Beam IV: Characterization
Sponsored by: TMS Materials Processing and Manufacturing Division, TMS: Powder Materials Committee, TMS: Additive Manufacturing Committee
Program Organizers: James Paramore, Texas A&M University; Daniel Lewis, Texas A&M University; Kyle Tsaknopoulos, Worcester Polytechnic Institute; Paul Prichard, Kennametal Inc.
Monday 8:30 AM
March 20, 2023
Room: 24A
Location: SDCC
Session Chair: James Paramore, United States Army Research Laboratory; Daniel Lewis, Texas A&M University; Paul Prichard, Kennametal Inc.
8:30 AM Invited
Shape and Microstructural Characterization of Commercially Pure Titanium Feedstock Powders for Cold Spray Additive Manufacturing: Newell Moser1; Nicholas Derimow1; Edward Garboczi1; Ozan Ozdemir2; Sinan Muftu2; Carlos Pfeiff2; Shawn Moylan1; 1National Institute of Standards and Technology; 2Northeastern University
As additive manufacturing (AM) technologies continue to develop towards more sustainable and energy efficient methodologies, there is a need for reducing the overall carbon footprint of the entire supply chain, specifically with feedstock powders. Typically, atomized powder undergoes several extraction and remelting steps before its end use in AM applications. However, there is an opportunity to utilize powders directly after the Hunter extractive metallurgical process to reduce energy costs. This work will discuss the characterization of commercially pure (Grade 2) titanium sponge particles directly after the Hunter process for the eventual use in cold spray AM (CSAM). CSAM has several advantages: low thermal impact on the substrate, no melting of the feedstock material, and compressive residual stresses within the final part. In this study, powder characterization includes shape, porosity, and microstructure measurements using a combination of techniques involving micro X-ray computed tomography and scanning electron microscopy.
8:50 AM
Capturing the Thermo-mechanical History of Additive Friction Stir Deposited Al6061 Using a Three-dimensional CFD Based Numerical Model: Nikhil Gotawala1; Hang Yu1; 1Virginia Tech
Additive friction stir deposition is a solid-state additive manufacturing process where the deposited material's microstructure is very similar to wrought material. The microstructure evolution during the process depends on their themo-mechanical history. So, this work aims to analyze the effect of thermo-mechanical history on the microstructure evolution of additive friction stir deposited Al6061. A three-dimensional CFD based numerical is developed to capture the thermo-mechanical history during the process. The numerical model consists of the conservation of momentum, mass, and energy. Here, additive friction stir deposition of Al6061 is carried out at 300 rpm tool rotational speed and 2 mm/s tool velocity. An EBSD scan was performed on the deposited material to analyze the microstructure evolution. The experimental results suggest homogenous microstructure evolution in the deposition region, which also matches with consistent thermo-mechanical history.
9:10 AM
Additive Friction Stir Deposition of IN625-316L Bimetal: Shreyash Patil1; Sameehan Joshi1; Mani Krishna Karri1; Madhavan Radhakrishnan1; Shashank Sharma1; Narendra Dahotre1; 1University of North Texas, Denton
IN625 possesses high strength and oxidation resistance, due to which it is preferred in aerospace and nuclear applications. Additive friction stir deposition of IN625 was carried out on SS316 substrate. Conventionally produced IN625 bar stock was used a feed material for deposition at 600rpm rotational velocity, 1.27mm/s liner tool velocity, and 0.27mm/s feed rate. The layer thickness of 0.5mm and deposit length of 50mm to deposit 4 layers. The deposited material was then examined by optical microscope, X-ray diffraction, scanning electron microscopy, electron back scattered diffraction and nanoindentation tests. The SEM and EBSD observations showed significant grain refinement of the deposit compared feedstock. Moreover, the interface showed significant extent of in-grain misorientation. The nanoindentation tests showed slight improvement in the hardness of 4.81GPa and reduced modulus of 218.65GPa, while the substrate measured hardness of 3.72GPa and modulus of 204.18GPa.
9:30 AM
Evolution of Precipitate Structure in AA7050 Produced by Additive Friction Stir Deposition: Jacob Strain1; Rekha Rao1; Zachary Tew1; Ismael Hidalgo1; Paul Allison2; Brian Jordon2; Luke Brewer1; 1University of Alabama; 2Baylor University
This presentation will highlight nanoscale precipitate evolution caused by additive friction stir deposition (AFSD). The AFSD process is rapidly developing for large-scale, solid-state additive manufacturing. While the material does not melt during AFSD, the material generally experiences temperatures in excess of 70% of the melting point. These elevated temperatures, combined with severe plastic deformation, evolve the nature of the eta and eta prime strengthening precipitates in the AA7050 material. We are applying electron microscopy and atom probe tomography (APT) to AA7050 produced by AFSD. In as-deposited material, a bimodal distribution of precipitate sizes is generated, with a significantly larger size than in in the wrought feedstock material (AA7050-T7451). STEM-HAADF imaging combined with electron diffraction shows the prevalence of the eta phase on grain boundaries after deposition. Further electron diffraction and APT measurements will allow for the differentiation between the eta and eta prime distributions in the feedstock and as-deposited material.
9:50 AM
Friction Stir Additive Manufacturing of Al-5083: David Garcia1; Tianhao Wang1; Sarvesha Rajashekara2; Richard Eberheim3; Arvind Agarwal2; Tanaji Paul2; Kenneth Ross1; 1Pacific Northwest National Laboratory; 2Florida International University; 3Solvus Global
Friction stir additive manufacturing (FSAM) is a direct progression from traditional friction stir lap welding to a hybrid additive-subtractive sheet lamination technique. Compared to traditional friction stir welding, the process-structure-property relationship in FSAM becomes obfuscated as the in-plane raster pattern and repeated thermal cycling from subsequent layer addition can lead to complex thermal gradients within the work piece. This work addresses these challenges in component-scale manufacturing by implementing robust temperature and forging force control algorithms and studying the effect of subsequent in-plane and out-of-plane material build up on the mechanical properties of Al-5083. Depending on the total heat input during processing the resultant yield strength can be varied by up to 12% and control of the tool overlap sees an increase in hardness of up to 18% from the base material. These results reflect the potential for local microstructure control through FSAM.
10:10 AM Break
10:25 AM
Effect of Additive Friction Stir Deposition Tool Geometry on Material Mixing and Microstructure Gradient of Al Alloys: Mackenzie Perry1; Hang Yu2; Greg Hahn3; 1NSWCCD; 2Virginia Tech; 3Virginia Polytechnic Institute and State University
Developing an understanding of the effect of tool geometry on material mixing and microstructure evolution during Additive Friction Stir Deposition (AFSD) is important for full implementation of the technology. In this work, we used three tools with different features on the bottom surface to print 2XXX series aluminum alloy feedstock onto 6XXX series aluminum alloy substrates. X-ray computed tomography is used to visualize the shape of the deposited material layer and the interface between dissimilar aluminum alloys. Depending on the tool (flat, two protrusions, or four protrusions), the shape of the deposited material interface is tunable from flat all the way to highly asymmetric and wavy for the same parameters. Electron backscatter diffraction is used to understand the microstructure progression. The microstructure of the deposited material was relatively uniform and fully recrystallized. The substrate material showed variable amounts of recrystallization that is location dependent..
10:45 AM
Physical Trends Unraveled by Integrated In Situ Monitoring in Additive Friction Stir Deposition-Enabled Repair: Kendall Knight1; Hang Yu1; 1Virginia Polytechnic Institute and State University
Additive friction stir deposition, or AFSD for short, is an emerging solid-state additive process that can provide wrought-like characteristics in high strength 7xxx Al. Ongoing research from Virginia Tech has shown that through-holes in AA7050 plates can be repaired with the post-repair fatigue life better than the bushing approach, nearly meeting undamaged fatigue life standards. To better understand how the AFSD repair process is governed by the repair strategy and repair geometry, a test matrix involving various repair dimensions and strategies has been conducted with the process physics comprehensively investigated via an integrated in situ monitoring platform. Clear physical trends are unraveled for the AFSD process fundamentals with important thermal and mechanical insights. With the temperature scaling patterns and printer feedback patterns revealed and correlated to the repair behavior, this work lays the foundation for understanding process physics linkages and component-level effects from AFSD repairs.
11:05 AM Cancelled
A Novel Solid-stir Continuous Extrusion of an AlMgSc Alloy: Aishani Sharma1; Abhijeet Dhal1; Anurag Gumaste1; Supreeth Gaddam1; Rajiv Mishra1; 1University of North Texas
Friction stir-derived solid-state processes leverage the synergistic effect of frictional heating and shear deformation to provide localized microstructural modification and control for the improvement of mechanical properties. In this view, a novel processing route - solid stir extrusion (SSE) has been evaluated to extrude Al alloys. The thermomechanical conditions accomplished via this technique make it a unique processing route for microstructural engineering and mechanical property enhancement. The tool rotation and tool geometry attributes provide a continuous shearing mechanism and a unique flow pattern engendering localized compositional heterogeneity and influencing the material properties. In this research, SSE has been performed on an AlMgSc alloy, and an attempt has been made to study the variation of properties with a spatial resolution of multiple length scales via nanoindentation and other mechanical testing techniques.
11:25 AM
Quantification of Defects in Binder-jet Printed Steel Parts Using Confocal Imaging and Machine Learning: Pooja Maurya1; P Pistorius1; 1Carnegie Mellon University
Defects like porosity and oxide inclusions greatly influence the quality of binder-jet printed (BJP) parts. Sintering reduces porosity, improving the integrity of BJP parts. Confocal laser scanning microscope (CLSM) assisted real time imaging, with a dew point generator (for controlling sintering atmosphere) greatly helps in understanding evolution of such defects during sintering. In the present work, an in-situ CLSM has been used to image the surface topography of 316L BJP coupons during sintering at 1380℃. Systematic experiments indicated that de-binding at 470℃ is complete within 90 minutes (under argon). The effect of critical parameters like sintering time and dew point / frost point (in an Argon-5%H2 atmosphere) on the evolution of porosity and oxide inclusions has been analyzed. Machine learning is used to process the in-situ CSLM images for quantifying porosity by correlating with ground truth (from optical microscopy).
11:45 AM
A High-throughput Process for Mechanical Characterization of Ceramic Materials Produced by Direct Ink Writing: Raphael Thiraux1; Lorenzo Valdevit1; Alexander Dupuy1; 1University of California Irvine
Technical ceramics have exceptional high-temperature mechanical properties, but their brittleness makes the fabrication of complex shapes challenging. Additive manufacturing techniques, such as Direct Ink Writing (DIW), enable the manufacture of parts with complex shapes, as well as architected materials characterized by geometrical features with controlled defect populations. However, expanding DIW methods to new systems is non-trivial due to changes in powder rheology and suitable printing parameters. Here, we develop a method to screen the mechanical behavior of new ceramic systems using DIW and investigate the effects of different defects produced during manufacturing on the mechanical behavior. First, we synthesize variants of an alumina-based ceramic system. Then, we manufacture single tracks of those systems using DIW and perform characterization and mechanical testing. Finally, we incrementally scale up to arrays of lines to track the evolution of defects in complex builds and investigate the role of these defects on their mechanical behavior.
12:05 PM
Characterization of an Additively-manufacturable Ammonium Perchlorate Composite Rocket Propellant: Dylan Purcell1; Michael Hargather1; Chelsey Hargather1; 1New Mexico Institute of Mining and Technology
Ammonium perchlorate composite rocket propellant (APCP) is a commonly used solid propellant in commercial and defense applications. Current solid rocket motors are manufactured through a propellant casting process, which has high associated costs and imposes limitations on the internal structure and composition of the motor. In the present work, an APCP propellant designed for additive manufacture is characterized in terms of viscosity and yield stress of the non-Newtonian uncured material, as well as the final product’s layer-bonding behavior and combustion performance. Spindle and extrusion-based viscometry methods are used to examine the uncured material, while microscopy and tensile testing are employed for the analysis of the cured structure. Combustion behavior is quantified using a strand-burning apparatus. Properties of the final product are compared to tabulated structural and combustion ranges for APCP, and the applications for the material are discussed.