Enhanced materials performance of Al/Ti/Al laminate sheets subjected to cryogenic roll bonding
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eng Lu, Kiet Tieu, Huijun Li, Ajit Godbole, and Xiong Liu School of Mechanical, Materials & Mechatronics Engineering, University of Wollongong, Wollongong, NSW 2500, Australia
Charlie Kong Electron Microscope Unit, University of New South Wales, Sydney, NSW 2052, Australia (Received 20 May 2017; accepted 14 August 2017)
Laminate sheets attract increasing attention from researchers and engineers. In this paper, Al/Ti/Al laminate sheets were fabricated by using cryogenic roll bonding for first time. The edge defects, mechanical properties, and interface bonding of laminate sheets by cryogenic roll bonding technique were compared with these by room-temperature roll bonding technique. Results show that there are some edge cracks in laminate sheets by room-temperature roll bonding while they do not appear when subjected to cryogenic roll bonding. The ultimate tensile stress of laminate sheets by cryogenic roll bonding increases up to 36.7% compared to that by room-temperature roll bonding. When laminate sheets are rolled to 0.125 mm from 2.025 mm, the interfaces between Al and Ti layers are bonded well for both cryogenic roll bonding and room-temperature roll bonding. Finally, we discussed the improvement in edge quality and mechanical properties and the mechanism of interface bonding of Al/Ti/Al laminate sheets during cryogenic roll bonding.
I. INTRODUCTION
In recent years, ‘sandwich’ laminate sheets have attracted a great deal of attention due to their excellent properties1–4 which make them ideally suited for diverse functions such as ballistic protection, heat exchange, blast mitigation, and vibration damping.5,6 Roll-bonding techniques have been successfully applied to fabricate multi-component materials with tailored properties by reinforcement or grading, such as Al/Ti,7–12 Cu/Ti,13,14 Al/Mg,15,16 Al/Cu,17,18 and Al/steel.19,20 For laminate sheets, rolling temperature generally affects the interface bonding quality and mechanical properties of the product.21–23 It has been observed that to obtain good interface bonding quality, it is better to raise the deformation temperature.24 For ferrous metals, rolling at a high temperature (.1273 K) is required to achieve good interface bonding.23,24 Interfaces of nonferrous metals can be bonded well under moderately
Contributing Editor: Yang-T. Cheng a) Address all correspondence to this author. e-mail: [email protected] or [email protected] DOI: 10.1557/jmr.2017.355
high-temperature rolling (;473 K).25,26 The bonding strength of metals at room-temperature roll bonding (;293 K) is related to the reduction ratio.27 It is seen that when the reduction ratio is larger than 70%, the metals can bond well.28,29 Compared to symmetric roll bonding, the bonding quality between layers can also be improved by asymmetric roll bonding.30,31 However, there are no reports on the fabrication of laminate sheets by cryogenic roll bonding technique. Cryorolling (,173 K), in which the samples are generally cooled by liquid nitrogen, has been considered as a severe plastic deformation
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