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

Abstract

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.