Slip in a stress gradient: Multiple slip and cross slip in an alpha brass single crystal oriented for easy glide

Abstract

Trapezohedron shaped specimens of α-brass, single crystals, oriented for single slip, were compressed in order to examine slip behavior in a stress gradient. Two dimensional finite element method calculations were carried out to determine expected elastic stress distributions. These calculations indicated that, at a given height above the base of the trapezohedron, the resolved shear stress for a particular slip system passed through a maximum along the specimen width. Also the height of the maximum varied with the slip system. From the resolved shear stresses and the observation that no slip occurred below a resolved shear stress of 7 MN/m 2, it was anticipated that only five slip systems would operate. Six slip systems were found to act, and it was inferred that the additional stress required to operate the sixth slip system was created by the simultaneous functioning of two of the slip systems. Cross slip occurred when the calculated resolved shear stress on the cross slip system was equal to the resolved shear stress on the primary slip system, an observation which suggested that cross slip occurred, when a critical resolved shear stress was reached. The complex stresses which developed in the trapezohedron suggest that the interaction of anisotropy and grain shape has a significant effect on the complex stresses developed within grains of polycrystalline metals.