Specimen geometry and its effect on flow curve in torsion testing – A review

Abstract

The metal forming processes plays an important role in aerospace, automobile and other industries for the manufacturing of complex shapes. In the metal forming processes, the components are subjected to plastic deformation, for which the material's plastic zone in a stress-strain relationship curve is of primary interest, as it provides considerable insight about the behaviour of material during forming. In the plastic zone, the material behaviour is defined by the flow curve. The flow curve is an effective representation of stress-strain behaviour of a material during plastic deformation. In determining the flow curve, Torsion test is used in determining strains where the strains of higher ranges (i.e., greater than 1) are achieved when compared to the uniaxial tension or compression test due to their limitations of necking and barreling respectively. Even though the torsion test is being used from long time, the specimens and its geometries are not well standardized. Many investigators used various types of specimen and geometry in torsion testing. The present work aims at consolidating the various types of specimen and its geometry used in torsion testing and to review its effect on the flow curve.