Deformation-induced Microstructural Evolution during Solid Phase Processing: Experimental and Computational Studies: Deformation Induced Microstructural Evolution I
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
Tuesday 8:00 AM
March 21, 2023
Room: 29C
Location: SDCC
Session Chair: Arun Devaraj, Pacific Northwest National Laboratory
8:00 AM Introductory Comments
8:05 AM Invited
Crystal Rotation Kinematics and the Activation of Different Twinning Systems due to Tribological Loading: Christian Greiner1; 1KIT
Already in 1950, Bowden and Tabor pointed out that in metallic tribological contacts the majority of the dissipated energy is spend to change the contacting materials’ microstructures. This - in part - explains why most metals show a highly dynamic subsurface microstructure under the shear load imposed by a sliding contact. One key process involved therein is the reorientation of the crystal lattice. Model experiments performed with high-purity copper bicrystals shed light on the early stage, fundamental mechanisms of tribologically induced lattice rotation kinematics. Electron backscatter diffraction (EBSD) performed directly on the wear track reveals a crystal rotation process around the transverse direction, irrespective of sliding direction, grain orientation and normal load. By making use of CoCrFeMnNi single crystals, we could identify that depending on the friction coefficient, different deformation mechanisms like dislocated mediated plasticity and twinning are being activated.
8:35 AM
Shear Deformation of Fe-Mn Alloys by High-speed Rotational Diamond Anvil Cell (HS-RDAC): Tingkun Liu1; Julian D Escobar Atehortua1; Changyong Park1; Arun Devaraj1; 1Pacific Northwest National Laboratory
Under high shear strain condition, e.g., solid phase processing (SPP) that enhances diffusivity due to excess defect density and deformation induced heating, the Cottrell atmospheres (local solute environments near dislocation) in alloys could be significantly more complex than those resulting from simpler annealing. We studied the microstructural evolution of Fe-Mn alloys caused by SPP within high-speed rotational diamond anvil cell (HS-RDAC) with in-situ synchrotron X-ray diffraction. The XRD results showed changes in the phase equilibrium as well as the dynamic defect density. We also studied the deformed alloys recovered from HS-RDAC with advanced electron microscopy and atomic probe tomography (APT), which revealed changes in the Cottrell atmospheres and the grain boundary segregation due to the shear deformation. This work provides a pathway toward direct experimental understanding of the influence of strain rate and temperature on shear deformation and its effects on the Cottrell atmospheres and the grain boundary dynamics.
8:55 AM
Robotic Blacksmithing: Towards the Autonomous Control of Geometry and Microstructure Via Iterative, Open-Die Forming: Michael Groeber1; Steve Niezgoda1; Glenn Daehn1; Tobias Mahan1; 1The Ohio State University
The use of advanced incremental forming has been validated by blacksmiths and parts can be made that are much larger than a given available press. Systems with large robots and modestly-sized presses can develop these large forgings and in a fraction of the current time as dies do not need to be designed or built. Beyond these practical advantages, the goal of this work is to produce components where location-specific material properties/performance metrics are met in addition to the geometry requirements. We will present an initial robotic system - both its cyber and physical components. We will also highlight initial results in achieving required component geometries with desired microstructural characteristics. We will also present the details of the control algorithms developed for the system to operate in a semi-autonomous manner.
9:15 AM Break
9:30 AM Invited
Chemistry and Phase Formation at Lattice Defects: Equilibrium Cases and Kinetics: Dierk Raabe1; 1Max-Planck Institute
We present and discuss a variety of chemo-structural phenomena caused by the interplay between an alloy’s chemical composition and its lattice defects. Observations are documented by using correlative atom probe tomography, electron microscopy and theory.The features discussed include such diverse phenomena as solute chemical decoration, partitioning and phase transformations at dislocations; dislocation-character-specific chemical decoration; and low-dimensional spinodal decomposition within interfaces. It is shown that some of these phenomena have a structural and kinetic background while others are thermodynamic in origin and can be explained by stable low-dimensional phase states at defects.
10:00 AM
Continuous Metal Processing of Ultrafine-grained Copper Sheets through Cold Angular Rolling Process: Isshu Lee1; Jae-Kyung Han1; Yun-Hsuan Wu1; Lukas Daut1; Brain Bay1; Melissa Santala1; Roberto Figueiredo2; Megumi Kawasaki1; 1Oregon State University; 2Universidade Federal de Minas Gerais
Cold angular rolling process (CARP) is a new severe plastic deformation (SPD) technique, which can refine microstructure and greatly increase their strength of sheet metals without any length limitations at room temperature and fast processing speed. CARP features a combination of cold rolling and equal-channel angular process (ECAP). Thus, CARP allows of multiple passes similar to the general ECAP operation, so that a desired microstructure and mechanical properties can be achieved in the processed metallic sheets. The current study demonstrates successful copper sheet processing at ~278K at 5 mm/sec. Structural evolution and mechanical property changes of the processed Cu sheets are examined by X-ray diffraction analysis, and optical microscopy, Vickers microhardness measurements, and tensile testing coupled with the digital image correlation method. Moreover, the finite element method was utilized for evaluating the experimental results and capabilities of CARP.
10:20 AM
Development of Solid-state Processing of Electrical Steels for Cost-efficient Electric Motors: Shivakant Shukla1; Hrishikesh Das1; Piyush Upadhyay1; 1Pacific Northwest National Laboratory
Higher Si (up to 6.5 wt%) contenting electrical steels possess favorable electrical and magnetic properties for the core of the induction motor rotors in electric vehicles. However, Si facilitates the formation of secondary ordered phases, making the alloy brittle and susceptible to cracking during the fabrication process, thus limiting mass production. This work examines the feasibility of friction stir processing (FSP) as a solid-state processing tool to improve the mechanical properties of the high Si-containing electrical steel while maintaining the desired magnetic and electrical response. FSP can modify the alloy microstructure without changing the composition. A variety of processing parameters like temperature, rotational speed, traverse speed, etc. are used to obtain samples at various conditions. Our study shows that processing temperature has a considerable effect on grain size. We also explore the effect of FSP parameters and subsequent microstructure on the mechanical, electrical, and magnetic properties.
10:40 AM
Studies on Defect- and Chemical Diffusion Driven Rapid Consolidation of New Ni Alloys: Yannick Naunheim1; Christopher A Schuh1; 1Massachusetts Institute of Technology
Additive manufacturing is an emerging pathway to produce metallic materials, usually by processing a well-established, commercial alloy via a powder-based approach. In this talk, we aim to invert this classical design approach: we selectively tailor and adjust the chemical composition of the alloy powder to make it suitable for rapid low-temperature solid-state consolidation. Acceleration of the consolidation process is based on two mechanisms: Nanocrystallinity achieved by high energy ball-milling can accelerate diffusion at low temperatures, while in some cases phase evolution through diffusional demixing and remixing of a second solute-rich phase can encourage the formation and growth of interparticle necks upon heating. The effect of individual alloying elements on the process thermodynamics are predicted using computational thermodynamics, which in turn provides a basis for an alloy design process. Example results on sintered microstructures are presented and discussed for the case of nickel-rich alloys.
11:00 AM
Ultrafine-grained Bonding Interface of 316L Stainless Sheets Processed by Ultrasonic Spot Welding: Jheyu Lin1; Hue-En Chu1; 1National Taipei University of Technology
In this study, ultrasonic spot welding was utilized to investigate the feasibility of joining hard stainless steel sheets. From microstructural characterization using scanning electron microscopy (SEM) and electron backscattered diffraction (EBSD), it is found that after 0.5 s welding time, an ultrafine-grained microstructure with a grain size distribution less than 500 nm was produced at the bonding interface. Such microstructure could be attributed to dynamic recrystallization, which originated from frictional heat and severe plastic deformation during USW, accompanied by deformation-induced martensite transformation near the bonding interface. As welding time increased, the bonding interface evolved to an even distribution of larger recrystallized grains with sufficient strength. In the future, we will further characterize such nano-grained microstructure using transmission electron microscopy and transmission Kikuchi diffraction techniques