Deformation-induced Microstructural Evolution during Solid Phase Processing: Experimental and Computational Studies: Deformation Induced Microstructural Evolution V
Sponsored by: TMS Materials Processing and Manufacturing Division, TMS: Shaping and Forming Committee
Program Organizers: Arun Devaraj, Pacific Northwest National Laboratory; Pascal Bellon, University of Illinois at Urbana-Champaign; Suhas Eswarappa Prameela, Massachusetts Institute of Technology (MIT); Mostafa Hassani, Cornell University
Thursday 8:30 AM
March 23, 2023
Room: 29C
Location: SDCC
Session Chair: Tingkun Liu, Pacific Northwest National Laboratory
8:30 AM Invited
Physical Metallurgy of Mechanochemical Ignition Processes in High Pressure Oxygen Environments: Zachary Cordero1; 1Massachusetts Institute of Technology
A key life-limiting component in next-generation reusable staged combustion rocket engines is the turbopump that pressurizes the propellants. The turbine entry temperature and O2 partial pressure in such devices are typically 350 to 750K and 300 to 600 bar, respectively; these O2 partial pressures are so high that they can cause conventional engineering alloys to ignite and burn uncontrollably. There are two main ignition mechanisms in the oxygen-rich turbine: frictional ignition due to rubbing of rotating components and particle impact ignition when small foreign objects entrained in the flow impact a solid surface. Both mechanisms have caused launch failures in expendable engines and delayed the development of reusable rocket engines. This talk will summarize our efforts to elucidate the physics underlying mechanochemical ignition phenomena by reproducing these processes in the laboratory.
9:00 AM
Characterization of Phase and Mechanical Developments of Martensitic α' Phase in Ti-6Al-4V Under Laser Processing via In-Situ Synchrotron X-ray Diffraction: Seunghee Oh1; Joseph Aroh1; Andrew Chuang2; Nicholas Lamprinakos1; Robert Suter1; Anthony Rollett1; 1Carnegie Mellon University; 2Argonne National Laboratory
Ti-6Al-4V (Ti64), one of the extensively studied alloys for additive manufacturing, is an α+β titanium alloy involving solid-state phase transformations. Under fast cooling conditions, i.e., laser processing, the high-temperature phase, β, is known to undergo a martensitic transformation. The reaction determines the microstructural and mechanical behaviors, which influence the material properties of the printed parts. In this study, an in-situ synchrotron X-ray diffraction with high temporal and spatial resolution is utilized to observe the rapid phase and mechanical development under laser processing. With the fully martensitic Ti64 prepared from as-printed parts, multiple in situ measurements are conducted to study how the phase configuration developed at different locations in the melt pool. The changes in the azimuthal distribution of lattice parameters imply anisotropic behavior of the deformation during laser processing. The spatial mapping analysis around the melt pool illustrates how phase evolution affects the macro-strain evolution.
9:20 AM
Local Modification of Microstructure and Mechanical Properties in 7000 Series Al Alloys Achieved by Friction Stir Processing: Tanvi Ajantiwalay1; Julian Escobar1; Jia Liu1; Matthew Olszta1; Nasim Wahaz1; Hrishikesh Das1; Mert Efe1; Piyush Upadhyay1; Arun Devaraj1; 1Pacific Northwest National Laboratory
Friction-stir processing (FSP) was used to modify the microstructure of three 7000 series Al alloys (7085, 7075 and 7055). The microstructural refinement achieved by FSP, including dissolution of nanoscale precipitates, grain refinement and matrix compositional changes were characterized by using multi-modal microstructural characterization approach with scanning and transmission electron microscopy and atom probe tomography. The unique microstructural changes brought about by the FSP were then correlated to the local changes in the mechanical properties. The local mechanical properties of the base alloy (BM) and stir zone (SZ) were investigated using an in situ PI89 Picoindenter implemented in a plasma focused ion beam/scanning electron microscope. Nanoindentation and micropillar compression show a reduced hardness and yield strength but higher strains are accommodated in the SZ for all three alloys. Such advanced characterization studies will help create a baseline for the microstructure and properties of FSP’ed 7000 series alloys.
9:40 AM
On The Plastic Deformation Path and Concurrent Microstructure Evolution During Additive Friction Stir Deposition-Based Solid-State Metal Additive Manufacturing: Hang Yu1; 1Virginia Polytechnic Institute and State University
Additive friction stir deposition is an emerging solid-state additive process that potentially addresses the quality control issues in beam-based metal additive manufacturing via high-temperature, rapid plastic deformation, which typically results in fully-dense material with equiaxed, fine grains in the as-printed state. Here, we explore the underlying deformation insights by integrating tracer-based experiment with process modeling. Using Al-Cu/Al-Mg-Si as the tracer/base material system, we employ X-ray computed tomography to unravel the plastic deformation path of the center and edge voxels in the feed material. The millimeter-scale cylindrical tracers are found to experience extrusion and torsion, followed by shear-induced thinning, ultimately forming micro-ribbons piling up along the deposition track. Microstructure mapping throughout the deformation path indicates significant grain refinement during initial material feeding via geometric dynamic recrystallization. Additional insights on the strain rate, total strain, flow stress, and Zener-Hollomon parameter at each deposition step are revealed through experiment-validated computational fluid dynamics modeling.
10:00 AM Break
10:15 AM
Strengthening of Pre-treated Aluminum During Ultrasonic Additive Manufacturing: Michael Pagan1; Ningxiner Zhao2; Leon Headings2; Marcelo Dapino2; Sriram Vijayan2; Joerg Jinschek3; Steve Zinkle1; Suresh Babu1; 1University of Tennessee; 2The Ohio State University; 3Technical University of Denmark
Severe plastic deformation occurs during ultrasonic additive manufacturing (UAM) to create solid-state bonding. This allows for UAM to bond foils of dissimilar or difficult to weld materials, and create unique structures for nuclear, defense, and aerospace applications. UAM technology development is complementary to an improved understanding of how the metallurgical interface develops. Additionally, UAM builds typically suffer from reduced yield strength in the transverse direction after foil bonding relative to bulk material prior to bonding. In this study, we pretreated an aluminum alloy to grow 2nd phase precipitates, then bonded the materials using UAM. Through multi-length scale characterization techniques, we demonstrated that the total build structure can increase in yield strength as well as individual foil-foil interfaces. This is due to dynamic recrystallization, dynamic recovery, adiabatic heating, precipitate dissolution, and enhanced elemental diffusion through deformation-induced defects, such as vacancies.
10:35 AM
The Relative Rates of Dynamic and Static Grain Growth in an Interstitial-Free Steel: Thomas Bennett1; Eric Taleff1; 1University of Texas at Austin
Grain growth is faster in specimens plastically deformed at elevated temperature than in specimens of the same material statically annealed under equivalent conditions, without deformation. These two cases of grain growth are termed dynamic grain growth (DGG) and static grain growth (SGG), respectively. The reasons for accelerated grain growth under DGG are investigated through experiments using a titanium-added interstitial-free (Ti-IF) steel sheet material. To induce DGG, specimens were deformed at 850 °C in tension under constant true-strain rates to true strains up to 0.23. SGG experiments were conducted at the same temperature. Electron backscatter diffraction (EBSD) data are used to examine the microstructures produced under both static and dynamic conditions. Grain size distributions and the subgrain structures evolved during DGG are characterized. Evidence is presented supporting the case for subgrain structures contributing to the faster grain growth observed under dynamic conditions.
10:55 AM
ARB Processing of Bulk Fe-Al and Ti-Al Nano-metallic Laminates: Thomas Nizolek1; Rodney McCabe1; Yifan Zhang1; Daniel Savage1; Cody Miller1; Carl Osborn1; Sean Raybon1; John Carpenter1; Laurent Capolungo1; 1Los Alamos National Laboratory
Accumulative roll bonding (ARB) is often touted as an ‘industrially relevant’ processing method for creating bi-phase nanolamellar composites. Yet stable co-deformation and refinement of lamellar structures has proven challenging for all but a few primarily immiscible material systems (Cu-Nb, Fe-Ag, etc.). The ability to produce technologically useful, engineering-scale nanolaminates using metals relevant to the automotive and aerospace industries (e.g. Fe-Al or Ti-Al) has remained elusive due to the propensity of these systems to either 1) neck and fragment during large-strain deformation or 2) react to form unwanted brittle intermetallic phases during processing. Here we demonstrate that ARB can be used to synthesize nanolamellar Fe-Al and Ti-Al composites without significant intermetallic formation or loss of layer continuity if both constituent mechanical properties and processing conditions are carefully controlled. These nanolaminates display remarkable flow stability during processing and possess exceptional mechanical properties (flow stresses >2 GPa at layer thicknesses of 25 nanometers).
11:15 AM Cancelled
Nano-structure, Mechanical Properties and Thermal Transport Properties of Nano-crystalline Eurofer97: Felix Hofmann1; Kay Song1; Gregory Strangward-Pryce1; 1University of Oxford
Severe plastic deformation allows the controlled nano-structuring of materials. This is attractive for materials exposed to intense irradiation environments, as interfaces can act as efficient sinks for irradiation damage, thus limiting irradiation-induced structural evolution. Here we report our recent work using high pressure torsion (HPT) to manufacture nano-grained Eurofer97, one of the main candidate materials for structural components in future fusion reactors. Using X-ray diffraction, we study the evolution of materials structure with the imposed deformation. This is combined with nano-indentation to determine mechanical properties and their link to the microstructure. Surprisingly thermal transport properties, measured by transient grating spectroscopy, also evolve considerably. By studying both as-manufactured and subsequently ion-implanted material we assess the stability of properties in the presence of irradiation damage. These results are contrasted with irradiation-induced property evolution in large, grained specimens of the same material.