PLASTIC BEHAVIOR OF COPPER SHEETS SUBJECTED TO A DOUBLE STRAIN-PATH CHANGE

Three sequences of three strain paths have been carried out on a polyc rystalline copper sheet: tension-rolling-tension with the rolling dire ction normal to the tensile axes; rolling-rolling-tension, the first a nd the second rollings being performed parallel and normal to the tens ile axis, respectively; and rolling-rolling-tension, the first and the second rollings being performed normal and parallel to the tensile ax is, respectively. In order to achieve a better understanding of the me chanical behaviour of the copper sheet under complex strain paths, the effects of double strain-path change on the subsequent reloading yiel d stress and residual uniform strain have been investigated. It is fou nd that the mechanical behaviour after reloading depends mainly on the orientation relationship between the previous and subsequent paths an d less on the order in which they have been performed. A ''hard'' orie ntation relationship between two strain paths, consecutive or not, str ongly imposes the effects of the prestrain path on the subsequent beha viour.