12th International Conference on Magnesium Alloys and their Applications (Mg 2021): Forming II
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 III
Location: Virtual
Session Chair: Bong Sun You, Korea Institute of Materials Science
Influence of As-cast Microstructure on Forging Behaviour of Magnesium Alloy AZ80: Jared Uramowski1; Paresh Prakash1; Erfan Azqadan1; Ali Roostaei1; 1University of Waterloo
The limitations of the internal combustion engine have driven alternate means of improving efficiency, such as using lightweight magnesium alloys for structural components. To meet structural strength and fatigue requirements the mechanical properties must be improved through forging, made difficult due to the crystal structure of magnesium. Research has shown that the mechanical properties of forged magnesium rely on the grain size, grain orientation, and internal defects of the as-cast starting material. This research focuses on the influence of the as-cast structure on the forging response and microstructure evolution of the AZ80 magnesium alloy. Flow stress is measured for samples cast with high and low cooling rates, and samples that were homogenized prior to deformation. The grain structure is analyzed at incremental strains during deformation for each starting material state. This knowledge will help to determine the optimal cast material structure that will enable structural components upon forging.
Effect of Caliber Rolling on Microstructure and Mechanical Properties of Wrought Mg-Bi Based Alloy: Hui Yu1; 1Hebei University of Technology
In this study, a Mg-1.32Bi-0.72Ca (BX11) alloy having bimodal grain structure was successfully fabricated by a new processing route of combining extrusion and 3 pass caliber rolling. This novel processing (E-CRed) demonstrates a necklace-like grain structure with ultrafine grains formed around the microscale deformed grains, which is remarkably different from the uniform microstructure of the as-extruded alloy. In addition, the E-CRed BX11 alloy exhibits strong basal texture which is mainly original from the large deformed grains. Furthermore, the E-CRed BX11 alloy represents excellent comprehensive mechanical properties, with an ultra-high yield strength of 351 MPa and a good elongation to failure of 13.2%. The significant strength improvement can be mainly attributed to the grain refinement and much stronger basal texture compared with the as-extruded sample.
Evolution of Texture and Microstructure in Mg-Zn-Ca Sheet Alloys during Thermomechanical Processing: Tracy Berman1; John Allison1; 1University of Michigan
The improved formability of advanced Mg sheet alloys has been attributed in part to their off-basal textures with a relatively low texture intensity. We have investigated the thermomechanical processing variables that produce these desirable textures in a systematic study of Mg-Zn-Ca alloys subjected to plane strain compression (PSC) using a Gleeble Thermomechanical Simulator. The PSC thermomechanical processing (TMP) route used consists of multiple compressive “hits” intended to simulate a multi-pass rolling process. This work utilizes microscopy and electron backscatter diffraction to track the evolution in microstructure and crystallographic texture that occurs during TMP at multiple stages in the processing path. We have demonstrated that the thermal soaks between passes and static recrystallization during the final annealing treatment play a particularly important role in determining the final texture. The effect of alloying and changes in processing conditions on the final texture are also important and will be discussed.
Cyclic Deformation Mechanisms and Fatigue Life Prediction of AZ31 Mg Alloy: Abbas Jamali1; Meijuan Zhang2; Anxin Ma2; Javier Llorca1; 1IMDEA Materials Institute & Technical University of Madrid; 2IMDEA Materials Institute
The low cycle fatigue behavior under fully-reversed cyclic deformation was determined in different orientations in an extruded AZ31 Mg alloy for different cyclic strain amplitudes. The shape of the cyclic stress-strain curves depended on the orientation due to the strong texture of the alloy and to the development of twinning under certain combinations of load and orientation. The mechanical response of the material under cyclic deformation was simulated by means of computational homogenization of a representative volume element of the microstructure of the alloy, The behavior of the Mg crystals followed a phenomenological crystal plasticity model which included all the different slip systems of Mg (basal, prismatic and pyramidal) as well as twinning and detwinning. The simulation results (in terms of the cyclic stress-strain curve and fraction of twinned material) were used to understand the cyclic deformation mechanisms and to predict the fatigue life from fatigue indicator parameters.
Texture Selection under the Influence of Solutes and Precipitates in Ternary Magnesium Rare Earth Alloys: Fatim-Zahra Mouhib1; Fengyang Sheng2; Talal Al Samman1; Sandra Korte-Kerzel1; 1Institute of Physical Metallurgy and Materials Physics, RWTH Aachen; 2RWTH Aachen University
Magnesium-rare earth alloys have gained increasing academic and industrial attention due to very attractive properties. In particular, enhanced cold ductility caused by a softened deformation texture has triggered great research efforts to understand microstructure evolution under the influence of solutes. However, the underlying mechanisms responsible for the formation of unique textures with a basal pole spread in the transverse direction and the interaction of multiple solute species (e.g. Zn & RE) is yet to be clarified. This work retraces the formation of a pronounced TD-split texture observed in Mg-1%Zn-1%RE (RE= Er, Dy, Gd) considering synergetic effects of multiple solutes and precipitates. From the results, texture selection seems to originate from selective growth during recrystallization, depending on solute concentration and species, as well as precipitates. Understanding the interplay of these factors is key for a microstructure-informed alloy design.