Deformation Induced Microstructural Modification: Session V: Deformation of Alloys II and Composites
Sponsored by: TMS Materials Processing and Manufacturing Division, TMS: Shaping and Forming Committee
Program Organizers: Arun Devaraj, Pacific Northwest National Laboratory; Suveen Mathaudhu, Colorado School of Mines; Kester Clarke, Los Alamos National Laboratory; Bharat Gwalani, North Carolina State Universtiy; Daniel Coughlin, United States Steel Corp
Wednesday 8:30 AM
March 17, 2021
Room: RM 38
Location: TMS2021 Virtual
Session Chair: Kester Clarke, Colorado School of Mines
8:30 AM
Grain Refinement and Bimodal Distribution of Precipitates in Al 6xxx and 7xxx Alloys during ShAPE (Shear Assisted Processing and Extrusion): Xiaolong Ma1; Rajib Kalsar1; Jens Darsell1; Miao Song1; Nicole Overman1; Keerti Kappagantula1; Vineet Joshi1; 1Pacific Northwest National Laboratory
Precipitation of fine intermetallic particles along with grain refinement is a crucial strengthening mechanism for alloys. The control of the particle size and distribution thus plays a key role in thermo-mechanical processing. ShAPE( Shear-assisted Processing and extrusion) is a recently developed appealing technique where rotational shear is superimposed to linear extrusion along with a self-generation of heat. However, how this unique condition affects the precipitation process of alloys still needs to be understood. In this study, we investigate the microstructures of two Al alloys (6061 and 7075) after the extrusion. We show that a bimodal distribution of precipitates is generated universally in both alloys. Particles as large as a few micrometers are often seen along grain boundaries, while small precipitates with less than ~100 nm are primarily dispersed in grain interiors. The results offer critical insight into how to tune the extrusion parameters to enhance the mechanical property of extrudates.
8:50 AM
Influence of Shear Rolling on Microstructure and Properties of Low-density Steels: Dean Pierce1; Tomas Scuseria1; Kelcey Garza1; Amrinder Gill1; Jerry Arnold1; Amy Clarke1; Kester Clarke1; Ercan Cakmak1; Artem Trofimov1; Hsin Wang1; Govindarajan Muralidharan1; Tom Muth1; 1Oak Ridge National Laboratory
Medium Mn low-density steels containing 5-10 wt.% Al exhibit interesting combinations of strength and reduced density for structural components. However, the hot rolled microstructures of these steels often contain large grains of δ-ferrite distributed in bands along the rolling direction and cube type textures, which can degrade strength and ductility. Some of these deleterious microstructural features may also remain after subsequent cold rolling and annealing. In this work, low-density steels were processed by asymmetric shear rolling to modify the microstructure through shear deformation, introduction of relatively high defect densities, grain refinement, and texture modification. The influence of asymmetric shear rolling on microstructural development and mechanical properties of low-density steels will be discussed.
9:10 AM
Investigation of Path Dependent Microstructural Evolution in Cu-Nb System Processed via Friction Consolidation: Mageshwari Komarasamy1; Xiao Li1; Scott Whalen1; Xiaolong Ma1; Nathan Canfield1; Matthew Olszta1; Tamas Varga1; Glenn Grant1; Suveen Mathaudhu2; 1Pacific Northwest National Laboratory; 2University of California, Riverside and Pacific Northwest National Laboratory
Understanding microstructural evolution in an advanced manufacturing process is crucial to paving the way towards science-aided manufacturing technology. In the current investigation, microstructural development in immiscible Cu-xNb (x=4, 10, and 50wt. %) alloys processed via friction consolidation of elemental powders was carried out. Friction consolidation is a solid phase processing technique that imparts severe strain into the deforming volume at elevated temperature. Two distinct processing conditions were chosen to understand the effect of thermomechanical pathways on the final microstructure. The microstructure was characterized using scanning electron microscopy, scanning transmission electron microscopy, and X-ray diffraction techniques. Significant differences in microstructural evolution between the two paths with respect to Cu grain structure and Nb particle size were noted. Furthermore, a brief discussion on mixing mechanism is presented based on deformation, thermodynamic and kinetic factors.
9:30 AM
Low Temperature Superplasticity in Al 5083 Produced by Accumulative Roll Bonding: Brady McBride1; Kester Clarke1; Amy Clakre1; 1Colorado School of Mines
Accumulative roll bonding is a novel severe plastic deformation technique used to produce ultrafine-grained material through repeated stacking and roll bonding. This process has provided pathways for low temperature superplasticity in certain aluminum alloys, such as Al 5083. Superplasticity in general is dependent on temperature and strain rate. These parameters become increasingly important with submicron-sized grains, as grain growth must be avoided to realize low temperature superplasticity by means of grain boundary sliding. This work explores the relationship between preheating, deformation temperature, strain rate, and the primary deformation mechanisms responsible for superplasticity during uniaxial tensile testing of Al 5083 produced by accumulative roll bonding.
9:50 AM
Tailoring the Mechanical Performance in Novel Zn-Ag-Mg Alloy Processed by Cold Plastic Deformation Processes: Maria Watroba1; Wiktor Bednarczyk1; Jakub Kawałko1; Terence G. Langdon2; Piotr Bała1; 1AGH University of Science and Technology; 2University of Southampton
Zinc and its alloys with potential applications as short-term implants have attracted recently great attention in the developing branch of biomaterials. However, brittleness and low mechanical strength limit their use for load-bearing applications. Zn also suffers other mechanical aspects related to recrystallization at strain rate sensitivity at room temperature. To address these issues a novel Zn-3Ag-0.5Mg alloy was fabricated using three processing paths: hot extrusion (HE), HE followed by cold rolling (CR), and high-pressure torsion (HPT). The extensive mechanical testing and SEM-EBSD microstructural characterization showed that coarse-grained samples after HE exhibited high strength with brittleness due to dislocation interaction with dispersed precipitates and, to some extent, with twinning activation. Significant grain refinement and processing at room temperature gave an increase in elongation in CR and HPT samples. Ductile CR samples and favorable rolling deformation texture gave mechanical properties meeting the requirements for biodegradable implants, and a reasonable strain rate sensitivity.
10:10 AM
The Unusual Effect of HPT Processing on Microstructure and Mechanical Properties in Zn-alloys: Wiktor Bednarczyk1; Maria Wątroba1; Jakub Kawałko1; Piotr Bała1; Terence G. Langdon2; 1AGH University of Science and Technology in Krakow; 2University of Southampton
High pressure torsion (HPT) processing in most cases produces an ultrafine-grained microstructure characterized by high angle grain boundaries and texture resulting from the characteristic deformation mechanism for the particular alloy group. Deviations from expected texture are rarely observed in single phase alloys. In this work pure zinc and low-alloyed Zn-Ag and Zn-Cu alloys were processed by HPT for 1/2 – 10 turns. Based on microstructural investigations three different deformation behaviors were identified. Pure Zn presents grain refinement up to 2 turns, and on further deformation grain growth was observed with crystallographic texture consistent with activation of 2nd order pyramidal slip system. After 5 turns the Zn-Cu alloy presents typical basal fiber texture with misorientation angle of all grain boundaries < 30°, while the Zn-Ag alloy presents previously not observed abnormal grain growth with 0001 direction parallel to the tangential direction and 11-20 direction perpendicular to the shearing plane.
10:30 AM
Mg-Fe Bonded Interface Using FaST: Hrishikesh Das1; Tianhao Wang1; Piyush Upadhyay1; Bharat Gwalani1; Xiaolong Ma1; Dalong Zhang1; 1Pacific Northwest National Laboratory
A few solid-state methods that employ high shear and shear rate at the interface have recently demonstrated viable bonds between “immiscible” pairs of Mg and Fe systems with and without the need for alloying elements. What might be the joining mechanisms responsible for bonding? We report on interface characteristics of bonded Mg-Fe interfaces made using Friction stir assisted scribe technique (FaST) to answer this question. The interface region consists of highly refined nano scale grains, Al and O segregation and intercalated regions. We will discuss latest results from micro and nano scale interface characterization including TEM and APT results for alloy and pure metal combinations and present joining mechanisms hypotheses and associated challenges in interpreting results.
10:50 AM
Harnessing Thermomechanical Processing to Influence Texture in ARB Cu/Nb Composites: Justin Cheng1; Sven Vogel2; Cody Miller2; Ryan Mier2; Carl Osborn2; John Carpenter2; Madhavan Radhakrishnan3; Osman Anderoglu3; Nathan Mara1; 1University of Minnesota Twin Cities; 2Los Alamos National Laboratory; 3University of New Mexico
ARB Cu/Nb nanolaminates have been studied extensively to link bulk processing parameters to changes in interface structure, microstructure, and extreme condition performance in layered heterophase composites. ARB Cu/Nb is known to have high strength, thermal stability, and radiation damage resistance enabled by interface structures that are strong dislocation traps and good point defect sinks. Past work on this topic has linked certain processing pathways to preferred crystallographic textures and to specific interfacial characters; annealing can sharpen existing textures in ARB composites, and changes in rolling direction can access transient textures. We present texture data taken from samples that have been annealed and subsequently subjected to different strain pathways to assess the degree to which we can sharpen and evolve textures in ARB composites. The current work will be discussed in terms of crystallographic stability under strain path changes, as well as the link between processing and material microstructure.
11:10 AM
Evolution of Mechanical Properties and Microstructure in Accumulative Roll Bonded FCC/BCC Metallic Composites: Thomas Nizolek1; Daniel Coughlin1; Cody Miller1; Nan Li1; Rodney McCabe1; John Carpenter1; 1Los Alamos National Laboratory
Accumulative roll bonding (ARB) is a severe plastic deformation technique used to synthesize metallic laminates with layer thicknesses ranging from the millimeter scale to the sub-micron scale. Here we use ARB to create metallic composites consisting of alternating layers of BCC iron and an FCC metal (either Cu, Ag, or Al). Depending on the processing route and the constituent phase flow stress mismatch, the composite material produced contains either 1) continuous iron and FCC metal layers or 2) fragments of iron layers in an FCC metal matrix as a result of necking and shear localization. We use nano-indentation to obtain phase resolved mechanical properties and bulk mechanical testing to measure the effect of layer morphology on the composite mechanical properties. The influence of grain size, layer continuity, and constituent phase flow stress mismatch on deformation during both processing and subsequent mechanical testing will be discussed.
11:30 AM
Analysis of Al 6061 and Mild Steel Joints from Rotary Friction Welding: Nikhil Gotawala1; Amber Shrivastava1; 1Indian Institute of Technology Bombay
This work focuses on the microstructure evolution upon rotary friction welding of Al 6061 to mild steel and resulting joint strength. Material deforms plastically during rotary friction welding, however, temperatures are low enough to prevent melting, which limits intermetallic compound formation. Displacement controlled rotary friction welding of circular workpieces is performed with combinations of three friction times (48 sec, 24 sec and 16 sec) and two rotation speeds (1200 rpm and 1400 rpm). Significant grain refinement is observed at the centre on Al 6061 side, which indicates dynamic recrystallization. However, only recovery is observed at the mild steel side, which is attributed to low temperatures. The maximum joint strength of 136 MPa is achieved. The fractured surfaces from tensile tests reveal sticking of Al 6061 on mild steel at the centre region. The fractured surfaces suggest ductile fracture in the centre region and brittle fracture close to the periphery.