Final Report: Research Area 10: Synthesis and Processing of Materials: Enhancing Deformation Processing Capability of Structural HCP Metals
Technical Report,05 Dec 2011,04 Dec 2014
Purdue University West Lafayette United States
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A study has been made of the interactive effects of large-strain deformation and deformation paths on microstructure and texture in structural hexagonal close packed metals, with magnesium as the model material system. Two methods are used to impose controlled deformation - large strain extrusion machining LSEM and wedge sliding. Controlled deformation paths accessed by LSEM have enables creation of Mg AZ31B sheet with novel shear textures, i.e., with basal planes tilted to the sheet surface, and fineultrafine grained microstructures. The development of the shear texture has been correlated with the deformation field measured using particle image velocimetry PIV. The shear texture, in combination with a fine grain size, has been shown result in enhanced combinations of strength and formability for LSEM sheet, compared to conventional rolled sheet. Furthermore, continuous sheet forms can be created in a single deformation step by LSEM by exploiting the adiabatic confinement of shear deformation intrinsic to the process, thereby minimizing the need for external heating. Under wedge sliding deformation, a new fluid-like flow and plastic instability has been discovered. This has also been identified as a key mechanism for particle formation and delamination wear in sliding, besides providing insights into how vortex-like lows develop and their relation to microstructure characteristics in ductile metals.
- Metallurgy and Metallography