Residual Microstress Development in Two-Phase Materials due to Tensile Deformation

Abstract

Residual stress development in steels having spherical cementite particles were investigated with a function of plastic strain and a volume fraction of cementite phase. Residual microstresses in both the matrix and the cementite phase were measured by means of X-ray diffraction. The results were compared with analytical prediction by the method of micromechanics and a finite element method.
Compressive residual stress was observed in the matrix phase after tensile deformation, whereas tensile one in the cementite phase. Each residual microstress increased linearly with plastic strain up to about 1×10^-2 for the specimen having a fine particle distribution. The increasing rate of residual microstress in the specimens depended on the volume fraction of the second-phase particles in agreement with theoretical prediction. The FEM calculation revealed inhomogeneous deformation in the matrix phase. This may be one of the reason why the increasing rate of residual microstress decreases with plastic elongation.