Post Deformation at Room and Cryogenic Temperature Cooling Media on Severely Deformed 1050-Aluminum

• Published in: Metals and materials international Vol. 24; no. 2; pp. 401 - 414
• Main Authors: Khorrami, M. Sarkari, Kazeminezhad, M.
• Format: Journal Article
• Language: English
• Published: Seoul The Korean Institute of Metals and Materials 01.03.2018; Springer Nature B.V; 대한금속·재료학회
• Subjects: Aluminum; Annealing; Characterization and Evaluation of Materials; Chemistry and Materials Science; Cooling; Cryogenic cooling; Cryogenic temperature; Deformation; Electron backscatter diffraction; Elongation; Engineering Thermodynamics; Friction stir processing; Grain boundaries; Grain orientation; Grain size; Grain size distribution; Grain structure; Heat and Mass Transfer; Indentation; Machines; Magnetic Materials; Magnetism; Manufacturing; Materials Science; Mechanical properties; Metallic Materials; Microstructure; Misalignment; Plastic deformation; Processes; Recrystallization; Solid Mechanics; Tensile tests; Ultimate tensile strength; Yield stress; 재료공학; Cooling media; Mechanical properties; Severe plastic deformation; Electron backscattered diffraction; Microstructure; Post deformation
• ISSN: 1598-9623; 2005-4149
• DOI: 10.1007/s12540-018-0037-3

The annealed 1050-aluminum sheets were initially subjected to the severe plastic deformation through two passes of constrained groove pressing (CGP) process. The obtained specimens were post-deformed by friction stir processing at room and cryogenic temperature cooling media. The microstructure evolutions during mentioned processes in terms of grain structure, misorientation distribution, and grain orientation spread (GOS) were characterized using electron backscattered diffraction. The annealed sample contained a large number of “recrystallized” grains and relatively large fraction (78%) of high-angle grain boundaries (HAGBs). When CGP process was applied on the annealed specimen, the elongated grains with interior substructure were developed, which was responsible for the formation of 80% low-angle grain boundaries. The GOS map of the severely deformed specimen manifested the formation of 43% “distorted” and 51% “substructured” grains. The post deformation of severely deformed aluminum at room temperature led to the increase in the fraction of HAGBs from 20 to 60%. Also, it gave rise to the formation of “recrystallized” grains with the average size of 13 μm, which were coarser than the grains predicted by Zener–Hollomon parameter. This was attributed to the occurrence of appreciable grain growth during post deformation. In the case of post deformation at cryogenic temperature cooling medium, the grain size was decreased, which was in well agreement with the predicted grain size. The cumulative distribution of misorientation was the same for both processing routes. Mechanical properties characterizations in terms of nano-indentation and tensile tests revealed that the post deformation process led to the reduction in hardness, yield stress, and ultimate tensile strength of the severely deformed aluminum.