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Deformation behavior of severely deformed al and related mechanisms through warm tensile test

Charkhesht, V ; Sharif University of Technology | 2017

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  1. Type of Document: Article
  2. DOI: 10.1007/s11665-017-2504-2
  3. Publisher: Springer New York LLC , 2017
  4. Abstract:
  5. Flow stress and ductility behaviors of the annealed and severely deformed Al were investigated at warm deformation temperatures. Constrained groove pressing (CGP) method as a severe plastic deformation process was used. The tensile test was carried out at the temperature range of the 298-573 K and strain rate range of 0.001-0.1 s−1 to present the elevated temperature deformation behavior utilizing hyperbolic sine constitutive equation. The flow stress of the CGPed sample is increased with the number of CGP passes and decreased with temperature. Dynamic recovery and strain softening are found as main restoration mechanisms. Flow stress amounts are not remarkably affected by the strain rate. Values of the elongation are decreased with the number of CGP passes. Values of the calculated strain rate sensitivity are utilized to justify the elongation behavior. Shear bands created by CGP remarkably decrease the fracture elongation values. Temperature interval of 298-473 K cannot remarkably affect the flow stress and ductility. The interval of 473-573 K is chosen as critical temperature interval in which the values of flow stress and elongation are remarkably decreased and increased, respectively. Increasing the temperature up to 573 K causes recrystallization in shear bands. Scanning electron microscope was used to study fracture surface which can truly predict the elongation behavior. With increasing the temperature, the shear decohesion area is gradually replaced with fully dimpled structures. Finally, hot deformation activation energy for CGPed samples was calculated about 85 kJ/mol which is close to the grain boundary diffusion activation energy in pure Al. © 2017, ASM International
  6. Keywords:
  7. Ductility ; Flow stress ; Fracture surface ; Severe plastic deformation ; Activation energy ; Aluminum ; Aluminum sheet ; Chemical activation ; Ductility ; Elongation ; Fracture ; Grain boundaries ; Plastic deformation ; Plastic flow ; Scanning electron microscopy ; Shear bands ; Tensile strength ; Tensile testing ; Constrained groove pressing ; Elevated temperature deformation ; Fracture surfaces ; Hot deformation activation energies ; Hyperbolic sine constitutive equations ; Severe plastic deformation process ; Severe plastic deformations ; Warm deformation ; Strain rate
  8. Source: Journal of Materials Engineering and Performance ; Volume 26, Issue 3 , 2017 , Pages 1311-1324 ; 10599495 (ISSN)
  9. URL: https://link.springer.com/article/10.1007/s11665-017-2504-2