Microstructural mechanism for the anomalous tensile behavior of aluminum-killed steel prestrained in plane strain tension

Abstract Aluminum-killed steel subjected to a tensile deformation following a prestrain in plane strain tension exhibits increases in yield strength, an earlier onset of strain localization and less work hardening than it would exhibit had it been subjected to an equivalent uniaxial prestrain. The effects are generally larger if the tensile axis is orthogonal to the prestrain axis. To understand the substructural origin of such anomalous behavior, transmission electron microscopy of the steel was performed after each step of processing. It has been found that, when the tensile axis is orthogonal to the prestrain axis, the dislocation cell structure of the prestrain becomes unstable and “dissolves”, whereas it is stable and reinforced if the tensile axis is parallel to the prestrain axis. These differences in substructure and the concepts of cell wall “polarization” and “memory” have been used to account for the anomalous tensile behavior of the prestrained material.