12th International Conference on Magnesium Alloys and their Applications (Mg 2021): Deformation & Mechanical Behaviors I
Program Organizers: Alan Luo, Ohio State University; Mihriban Pekguleryuz, McGill University; Sean Agnew, University of Virginia; John Allison, University of Michigan; Karl Kainer; Eric Nyberg, Kaiser Aluminum Trentwood; Warren Poole, University of British Columbia; Kumar Sadayappan, CanmetMATERIALS; Bruce Williams, Canmetmaterials Natural Resources Canada; Stephen Yue, Mcgill University
Wednesday 10:50 AM
June 16, 2021
Room: Contributed II
Location: Virtual
Session Chair: Dietmar Letzig, Magic-Magnesium Innovation Centre
A Micromechanics-based Modeling of Twin Evolution in Hexagonal Closed Packed Metals: Yubraj Paudel1; Christopher Barrett1; Haitham El Kadiri1; 1Mississippi State University
Twin nucleation is an important phenomenon leading to anisotropy and damage in magnesium AZ31 alloy. The strain path anisotropy in magnesium AZ31 alloy results from profuse nucleation of {10-12} twinning under c-axis tension (tension twinning) or d-axis compression (extension twinning) while damage induces from various interactions between twins and other grain defects. This work demonstrates that micromechanical work field calculations can have great potential to guide laws for crystal plasticity to predict twin patterning. The study shows a minimum energy path of twinning evolution through twin nucleation, propagation, and growth. The investigated twinning behaviors include twin propagation to the neutral axis, nucleation of a second twin at a certain distance from the first one, and twin growth with the microstructure finally evolving to a favorable twinning pattern to accommodate the total bending strain. The twinning mechanisms observed from this analysis compare well with the experimental results.
Influence of the Manufacturing Process on the Formability at Room Temperature of Magnesium Flat Products: Maria Nienaber1; Jan Bohlen1; Karl Ulrich Kainer2; Dietmar Letzig1; 1Helmholtz-Zentrum Geesthacht; 2Wrocław University of Science and Technology
The development of flat products made of Mg-alloys with excellent formability at room temperature is of interest. Besides rolling, extrusion also offers the possibility of producing flat products. During extrusion, it is possible to produce a finished flat product in only one processing step by a high degree of deformation, which also results in different texture and microstructure development compared to the rolling of sheets. However, compared to the rolling process, the band width during extrusion is very limited due to the process layout. In this work, conventional rolled sheets as well as extruded flat bands of different alloy compositions will be investigated and compared. The influence on the texture and microstructure development as well as on the strain rate dependent mechanical properties and the forming behaviour will be shown and discussed. It can be shown that the manufacturing process has an important and alloy dependent influence on the formability.
The Influence of Recrystallization on the Temperature Dependence of Twinning in Magnesium Alloys: Abhijit Brahme1; Kaan Inal1; Rak Mishra1; Amir Farzadfar2; Etienne Martin3; 1University of Waterloo; 2Corning Incorporated; 3École Polytechnique
The nucleation of twin formation, an important mechanism in the deformation of magnesium alloys, is still an active topic of discussion. The twin formation is generally tied to the amount of shear stress resolved on the twin system. This work sheds light on the formation of twins by studying the deformation in 3 different Mg alloys. The alloys are deformed at 350C. The flow curves show the signature of dynamic recrystallization in all the alloys. The resultant microstructures are studied optically and using electron backscatter diffraction maps. The results clearly show the formation of dynamic recrystallized (DRX) grains are primarily located inside the twins. The volume fraction of DRX and twins is calculated using ASTM E562-02 standard from the optical micrographs. The volume fraction of DRX and twins thus calculated shows inverse correlation. Thus, indicating that the increase in the DRX leads to decrease in the amount of twinning by reduction in the conditions conducive for twin formation.
Characterization of Twinning and Dislocation Slip in Magnesium Single-crystals by High Spatio-temporal Resolution: Kristián Máthis1; Petr Harcuba1; Dávid Ugi2; Michal Knapek1; Péter Ispánovity2; István Groma2; 1Charles University; 2Eötvös Loránd University
A combination of in-situ scanning electron microcopy (SEM), acoustic emission (AE) technique and high-speed camera recording has been employed for study the mechanical behavior of Mg single crystals. The combination of these techniques enables to study the active deformation processes with exceptional spatiotemporal resolution. The kinetics of the twinning and dislocation slip is discussed in detail and compared with molecular dynamics and finite element method simulations. The causality of deformation mechanisms is revealed by statistical analysis of AE data.
Effect of Yttrium and Cerium on the Pyramidal Slip in Magnesium Single Crystals: Shinji Ando1; Masashi Sakamoto1; Tomohiro Hanada1; Masayuki Tsushida1; Hiromoto KItahara1; 1Kumamoto University
Tensile tests of Mg-Y and Mg-Ce single crystals at various temperature were carried out to investigate alloying effects on activity of pyramidal <c+a> slips. Both alloy single crystals were yielded by activation of {11-22}<11-23> second order pyramidal slips at low alloy concentration. In Mg-Y alloy, {10-11}<11-23> first order pyramidal slip appeared at high yttrium contents and the CRSS of the pyramidal slip increased. The CRSS of second order pyramidal in Mg-Ce was lower than that of pure magnesium. Effect of yttrium and cerium on the CRSS of pyramidal slips was discussed based on dislocation mechanism of pyramidal slip.