Computational assessment of the microstructure-dependent thermomechanical behaviour of AlSi12CuNiMg-T7 - methods and microstructure-based finite element analyses

In this paper, the influence of the microstructure of a cast aluminium alloy used for pistons in combustion engines on the local and global deformation behavior is investigated by means of microstructure-based cell models and the finite element method. Therefore, a representative microstructure is digitized using nano computer tomography. In the digitized and segmented data, the aluminium matrix, silicon particles, pores and two intermetallic phases are distinguished. Microstructure-based cell models are created and linear-elastic, thermal and viscoplastic material properties are assigned for the finite element simulation in ABAQUS/Standard. The elastic, macroscopic nearly isotropic material behavior is shown for 64 different microstructure-based cell models with 200 × 200 × 200 elements with microstructure-dependent material properties at room temperature. A microstructure cell is subjected to a thermal cycle with zero macroscopic loading in order to examine the influence of the thermal mismatch between the individual microstructure phases on the resulting stresses and strains on the micro level. High stresses at interfaces of silicon particles and the aluminium matrix occur in the linear-elastic simulation, whereas an elastic-viscoplastic material behavior of the aluminium matrix leads to a overall stress relief in the microstructure cell.