Microstructural evolution and mechanical properties of ultrafine grained AA2024 processed by accumulative roll bonding

• Published in: International journal of advanced manufacturing technology 2017-10, Vol.93 (1-4), p.681-689
• Main Authors: Khatami, Ramin, Fattah-alhosseini, Arash, Mazaheri, Yousef, Keshavarz, Mohsen K., Haghshenas, Meysam
• Format: Article
• Language: English
• Subjects: Aluminum base alloys; Ambient temperature; CAE) and Design; Computer-Aided Engineering (CAD; Diffraction patterns; Dimpling; Dislocation density; Ductile fracture; Elongation; Engineering; Fracture surfaces; Grain refinement; Grain size; Heat treating; Industrial and Production Engineering; Mechanical Engineering; Mechanical properties; Media Management; Microstructure; Original Article; Roll bonding; Room temperature; Scanning electron microscopy; Tensile strength; Tensile tests; Ultrafines
• ISSN: 0268-3768; 1433-3015
• DOI: 10.1007/s00170-017-0547-z

In this paper, ambient temperature (room temperature) accumulative roll bonding (ARB) is performed on Al2024 aluminum alloys to assess grain refining phenomenon. The microstructural evaluations show reduction in the grain size from about 25 μm to about 350 nm by a factor of ∼70 upon six cycles of ARB; X-ray diffraction patterns were used to assess the increase in the dislocation density. The yield and tensile strength of the ultrafine grained Al2024 after the sixth cycle, 465 and 492 MPa, were about 650 and 186% higher than that of the as-received sample, 62 and 172 MPa, respectively. Investigating the fractured surfaces of the tensile test specimens by scanning electron microscopy showed that ARB process alters the mode of fracture substantially; fracture surface of annealed sample consists of deep equiaxed dimples which is an indication of ductile fracture. However, this changes in the ARBed specimens to shear ductile rupture with shallow and small elongated dimples.