Yield-Point Phenomena of Ti-20V-4Al-1Sn at 1073 K and Its Constitutive Modelling

Abstract

The deformation behaviour of β titanium alloy Ti-20V-4Al-1Sn sheet at 1073 K was investigated by performing uniaxial tension experiments. The stress-strain curves show a sharp yield point and the subsequent abrupt yield drop followed by the strain softening. From the EBSD analysis, a crystallographic misorientation was found in grains even at an early stage of yielding, even though the dynamic recovery had not yet taken place. To describe such a characteristic stress-strain response, a viscoplastic constitutive model is proposed that is built on the premise that the yield point phenomena are associated with the rapid dislocation multiplication at an early stage of yielding.