Strain function analysis method for void closure in the forging process of the large-sized steel ingot

A mathematical methodology for analyzing void closure in the forging process of steel ingot with a large size was proposed from the view of strain function. A numerical simulation of the forging process was established to describe the distribution field of compressive strain within deformed steel ingot. Then the analytic function of compressive strain distribution was given by mathematical fitting on the basis of Gaussian function (including the models without and with void). And finally the quantitative relationship between void closure and compressive strain, namely mathematical expressions of the criterion for central and non-central void closure, was presented by derivation and calculation of this function. The criterion for central and non-central void closure was verified by finite element simulation for a typical steel ingot. This new methodology gives an acute prediction in terms of elimination of void defects, where the deviation is less than 7%.