Effect of Microstructure and Hydrogen Pores on the Mechanical Behavior of an Al7%Si0.3%Mg Alloy Studied by a Combined Phase‐Field and Micromechanical Approach

A combination of the phase‐field method for the simulation of the microstructure evolution during solidification with subsequent finite element simulation of fracture appearance in the final solidification structure is proposed for the prediction of the mechanical behavior of AlSi based casting alloys, including the effect of solidification porosity caused by hydrogen. Metallographic investigations and computer tomographic observations of the as cast microstructure of an Al7%Si0.3%Mg alloy together with the data obtained from mechanical tensile testing are used to compare and validate the simulation results to demonstrate the capabilities as well as current limitations in micromechanical modeling of void containing materials. In micromechanical simulations with the element elimination technique (EET) it is shown that porosity influences the crack path as well as crack propagation by connecting the pores. In the eutectic microstructure without porosity, failure starts to develop in silicon lamellae and proceeds in the ductile matrix. However, in the presence of pores fracture also initiates in silicon, and in the later stages of loading, porosity affects the path of the crack and results in additional crack nucleation, and thus, these pores also influence crack propagation in the matrix.