MODELING THE ONSET AND EVOLUTION OF HYDROGEN PORES DURING SOLIDIFICATION

摘要

A quantitative prediction of the amount of gas microporosity in alloy castings is performed with a continuum model of dendritic solidification. The distribution of the number and size of pores is calculated from a set of conservation equations that solves the transport phenomena during solidification at the macro-scale and the hydrogen diffusion into the pores at the micro-scale. A technique based on a pseudo alloy solute which is transported by the melt is used to determine the potential sites of pore growth, subject to considerations of mechanical and thermodynamic equilibrium. Two critical model parameters are the initial concentration of the pseudo solute and the initial size at which pores start to grow. The dependence of the model prediction on these parameters is analyzed for aluminum A356 plate castings and the results are compared with published experimental data.