Elastoplastic modeling of materials supporting multiphase deformations

Stress–strain curves with peak stress, sudden dropping and the Maxwell stress plateau were widely observed in experiments on strips composed of materials supporting multiphase deformations. The peak-drop-plateau-type curves told us how phase transformations had occurred in the materials, but could not be used to explain why phase transformations could occur in the materials. An effective method to draw out a mechanical property curve of the material from its peak-drop-plateau-type curve is suggested in the present paper. It is shown that, through proper choices of the lower yield stress, a stress–strain curve with strain-softening behavior can be obtained, and can be applied to predict the multiphase deformations observed in experiments. As an illustration, a mechanical property curve of fine grained steel is obtained from its peak-drop-plateau-type curve, and is used to analyze kinking of strips, the Maxwell stress, the inclination angle of the Lüders band, kink angle of the strip, and both stress and strain in the Lüders band are predicted analytically. The predicted results are in reasonable agreement with the experimental measurements.