Effect of Initial Microstructure on Properties of Cryorolled Al 5052 Alloy Subjected to Different Annealing Treatment Te
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Effect of Initial Microstructure on Properties of Cryorolled Al 5052 Alloy Subjected to Different Annealing Treatment Temperatures N.M. Anas, B.K. Dhindaw, H. Zuhailawati, T.K. Abdullah, and A.S. Anasyida (Submitted January 16, 2018; in revised form August 11, 2018) Al 5052 alloy sheets were subjected to different pre-annealing temperatures (150, 200, 250, 300, and 350 °C) prior to cryorolling. The process resulted in Al 5052 alloys with different initial microstructures. The preannealed alloy sheets were compared with a cryorolled sample not subjected to pre-annealing. The thicknesses of the alloy samples after cryorolling was reduced by 30%. The pre-annealed cryorolled samples exhibited low crystallite size, and high lattice strain. Among them, the cryorolled sample preannealed at 300 °C had the lowest crystallite size, and the highest lattice strain. Changes in initial microstructure of this sample resulted in a significant improvement in its hardness (88 Hv), tensile strength (333 MPa), and corrosion resistance. The sample had the highest corrosion resistance among the cryorolled samples. Keywords
Al 5052 alloy, annealing, corrosion, cryorolling, strength
1. Introduction The development of ultrafine grains (UFGs; 100–1000 nm) of aluminum alloys for structural application is gaining considerable attention because they exhibit high strength at ambient temperatures without degrading their toughness. Severe plastic deformation (SPD) methods are successful in producing UFG in bulk form. Equal channel angular pressing (Ref 1-3), accumulative roll bonding (Ref 4), and high-pressure torsion (Ref 5) are some of the well-known SPD techniques that produce bulk UFG materials. The shapes of these materials do not change during the SPD processes. Cryorolling is one of the novel routes used to produce UFG structures in bulk materials. In this method, a material is subjected to rolling at cryogenic temperature, which leads to the suppression of dynamic recovery; therefore, the grain refinement resulting from cryorolling is far superior to other SPD techniques (Ref 6). It has been reported that high strength and ductility were achieved simultaneously for cryorolled Cu with bimodal microstructure (Ref 7). The combination of cryorolling and low temperature annealing was able to produce multimodal grain structure composed of coarse grains, ultrafine grains, and nanoscale grains. In another study, the formation of multimodal grains in hexagonal closed pack (HCP) structure of Zr was attributed to the high density of dislocations stored in the metal during N.M. Anas, H. Zuhailawati, T.K. Abdullah, and A.S. Anasyida, Structural Niche Area, School of Materials and Mineral Resources Engineering, Universiti Sains Malaysia, Engineering Campus, 14300 Nibong Tebal, Pulau Pinang, Malaysia; B.K. Dhindaw, School of Minerals Metallurgical and Materials Engineering, IIT Bhubaneswar, Bhubaneswar 751007, India. Contact e-mail: [email protected].
Journal of Materials Engineering and Performance
cryorolling process
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