Finite Element Simulation of the Distribution of Micro-Stress and Strain of Multiphase Steel

Abstract

By using the finite element method (FEM), the stress-strain curves of multiphase steels was simulated based on the stress-strain curves of single-phase ferrite, bainite, and martensite steels; then the measured result was compared with the simulated one. Effective factors such as the different distribution of microstructure, the volume fraction of hard phase and the yield stress ratio between single-phase hard phase steel with single-phase ferrite steel in multiphase steel are discussed in this work. The results show that the simulated result closely fits the measured one, which proves that this FEM built in this work is correct. The coarser the microstructure, the higher the drag effects of bulk structure, and the larger deformation degree of ferrite phase. With the increase of bainite and martensite volume fraction, the maximum stress rise gradually and the maximum strain decreases gradually. Meanwhile, the effects of volume fraction of hard phase on the stress-strain curve of multiphase steels are larger than that of yield stress ratio between single-phase hard phase steels and single phase ferrite steel.