Modelling and simulation of A-segregates in steel castings using a thermal criterion function: Part I - Background and validation

The present paper is the first out of two papers in which thermal criteria for modelling and
optimising, i.e. minimising, the formation of A segregates are investigated. One specific thermal
criterion has been incorporated into a transient three-dimensional thermal fluid model inside a
commercial simulation software package. It is then used for predicting A segregates inside a
large steel casting, i.e. a forging ram. In part I, experimental data obtained from a foundry serve to
validate the given criterion and to evaluate the critical value for A segregate initiation for one alloy
composition on the forging ram. In part II, the criterion forms the basis of shape optimisation of the
original casting layout for the ram. More specifically, unknown optimal shapes and sizes of the top
riser and chills are sought by means of autonomous optimisation to establish a better solidification
pattern, which would eliminate the likelihood of centreline porosity and A segregates.