An analytical approach for necking and fracture of hard layer during accumulative roll bonding (ARB) of metallic multilayer

The critical strain for the onset of necking and fracture in the hard layer during accumulative roll bonding (ARB) of metallic multilayer was predicted using the analytical models. The critical strain for necking was determined by utilizing an instability criterion and the critical strain for fracture was predicted based on the Cockcroft and Latham criterion using the tensile fracture strain. The stress state was derived in the hard layer at the exit of the roll-gap after n ARB cycles. The models predicted that the critical strain for necking and fracture increased with increasing the thickness ratio, strength coefficient ratio and the work-hardening exponent of the hard phase while it decreased with increasing the work-hardening exponent of the soft phase. The results of the model were verified by the data extracted from the literature. In addition, ARB experiments were performed on Al/Cu and Al/Ni multilayer in order to validate the analytical model and to investigate the microstructure evolution. (C) 2015 Elsevier Ltd. All rights reserved.