Pan American Materials Congress: Materials for Transportation and Lightweighting: Structure-Property Relationships II
Sponsored by: Third Pan American Materials Congress Organizing Committee
Program Organizers: Mary Wells, University of Waterloo; Rafael Colás, Universidad Autónoma de Nuevo León; Fernand Marquis, San Diego State University; Ramalinga Viswanathan Mangalaraja, University of Concepcion; Marta Lopez, University of Concepcion; Elvi Dalgaard, Pratt & Whitney Canada; Patricia Zambrano, Universidad Autonoma de Nuevo Leon

Tuesday 3:40 PM
February 28, 2017
Room: Mission Hills
Location: Marriott Marquis Hotel

Session Chair: Ramalinga Viswanathan Mangalaraja, University of Concepcion

3:40 PM  Cancelled
Cyclic Deformation Characteristics of AM30 Mg Alloy Extrusion along Two Orthogonal Directions: Ali A. Roostaei1; Hamid Jahed1; 1University of Waterloo
    Anisotropic cyclic behavior of AM30 Mg alloy extrusion is investigated by performing fully-reversed strain-controlled tension-compression tests at various strain amplitude levels along extrusion (ED) and transverse (TD) directions. Based on the results, the specimens cut along ED exhibit more extensive occurrence of twinning/detwinning during cyclic deformation, which results in higher degree of asymmetry of hysteresis loops. In addition, the stress response of ED specimens is higher than that of TD specimens. Texture measurements are employed to confirm the larger extent of twinning upon straining in ED. Final fracture surface morphologies are also studied and related to twinning and slip deformation mechanisms in ED and TD specimens, respectively.

4:00 PM  
Understanding of Twin-twin Junctions in Connection with the Local Stresses in HCP Magnesium: M. Arul Kumar1; Irene J Beyerlein1; Carlos Tome1; 1Los Alamos National Laboratory
    HCP magnesium alloys are very attractive candidate materials for lightweight transportation due to their low density and high specific strength. Understanding of the deformation behavior of these metals can enhance their formability and so their applicability. HCP-Mg accommodates deformation by slip and twinning and leads to slip-slip, slip-twin and twin-twin interactions inside grains. Among all three types, twin-twin interactions are not as well understood and not accounted for in current modeling tools. In this work, we employ a full-field Fast-Fourier-Transform(FFT) model to understand twin-twin interactions and their connection with local stresses. We find using FFT based local stress calculations that: i)twin-twin junction formation creates a large deviation of the twin boundary from the coherent twin plane; ii)formation and strengthening of these junctions is a self promoting process; iii)the presence of twin-twin junctions leads to local twin thickening; and iv)the presence of twin-twin junctions may suppress detwinning upon load reversal.

4:20 PM  
Effect of Forging on Microstructure, Texture and Compression Behaviour of Extruded AZ31B: Dwayne Toscano1; Sugrib Shaha1; Hamid Jahed1; Mary Wells1; Bruce Williams2; Jonathan McKinley2; 1University of Waterloo; 2CanmetMATERIALS
    Forging is a common method employed in the fabrication of automotive components. In this study, extruded AZ31B magnesium alloy was semi-close die forged at a temperature of 500 °C with a rate of 0.4 mm/s followed by microstructure analysis and uniaxial compression testing. Microstructural study indicated a refined grain structure in the forged samples compared to the bi-modal grain structure in the as-extruded sample. Also, the forged samples exhibited strong to weak texture depending on the location in the forged component. The obtained compression results showed a remarkable improvement of fracture strain of 16.8% in the forged samples compared to the extruded samples (9.1%), while an ultimate compressive strength of 236.7MPa and 287.6MPa was observed along the radial direction of the forged and as-extruded samples, respectively. It is attributed that the modification of microstructure and texture decreases the twinning and increases the slipping activity resulting the improvement of ductility.

4:40 PM  
Effects of Hypoeutectic Sc Additions to Al-4.5 wt% Cu under Different Cooling Rates: Abdoul-Aziz Bogno1; Jonas Valloton1; Hani Henein1; Mark Gallerneault2; Dieter Herlach3; 1University of Alberta; 2ALCERECO INC.; 3DLR,Institute of Materials Physics in Space
    Lightweight materials are the best response to improving performance and efficiency of sport and transportation industrial products. Aluminum is one of the most attractive lightweight materials due to its low density and a high strength to weight ratio achievable through cold working and/or heat treatment. Age hardenable Al-Cu alloys are one of the strongest aluminium alloys available. Sc, though very expensive, is renowned for yielding the highest strength increase per atomic percent of any alloying addition in Al through grain refinement of hyper-eutectic Sc compositions and precipitation hardening. This paper studies the solidification of Al-4.5wt%Cu with minor Sc additions (hypo-eutectic compositions) over a wide range of cooling rates. The objective is to determine the minimum Sc addition for a maximum strengthening effect while reducing typical processing steps. Based on the microstructures and mechanical properties analyses, a cost and time effective processing route is proposed for the 2000 series aluminum alloys.

5:00 PM  
Microstructure and Hardness of Subzero Quenched and Heat Treated Ti-6Al-4V Alloy: Abdelrahman Abbas1; Andrew Seif1; Iman El Mahallawi2; Waleed Khalefa2; 1British University in Egypt; 2Cairo University
    Titanium is one of the most important materials nowadays with promising lightweight demanding applications. However, despite its high strength-to-weight ratio, high temperature stability and high corrosion resistance, it has relatively low hardness. It is shown in this work that enhanced hardness values could be obtained for Ti-6Al-4V Alloy after heat treatment consisting of subzero quenching in a medium made up of dry ice and alcohol, followed by an aging treatment. The proposed heat treatment resulted an increase of 25% in the hardness of the alloy, compared to 5% reported in literature.