Effect of microstructure features on the mechanical properties of spheroidized steel by crystal plasticity method.

Finite element method based on crystal plasticity becomes a powerful tool in investigating mechanical properties of ferritic steel and dual phase steel. In this work, a three-dimensional, microstructure-based representative volume element method is employed for simulating the mechanical properties of the alloy steel 42CrMo4, a typical spheroidized ferrite–cementite steel. A computer program has been developed to generate automatic models considering microstructural features such as grain size, volume fraction, distribution of particles, ferrite texture and carbide bands in ferrite–cementite steel. The spheroidized cementite is generally without plastic deformation under the normal tensile test even at the fracture moment. Crystal plasticity constitutive law is employed to model the ferrite grains employing Huang’s code in Abaqus software. Material hardening parameters are determined and calibrated by comparing simulated tensile tests with experimental stress-strain curves. To study the influence of microstructure features and the capability of this method to predict the material mechanical behavior, several 3D samples including different microstructural features are modeled. The results show that when the proportion of cementite in the steel increases, the strength of the steel increases accordingly. Although in this study a random texture is assigned to crystalline aggregates, the code is capable of working with any texture data. Also, effects of ferrite grain size and carbide band which leads to the microstructure inhomogeneity and stress concentration are studied.