Grain size prediction of alloy 718 billet forged by radial forging machine using numerical and physical simulation

Abstract

Fine grains are required for Alloy 718 to obtain its high strength. Since grain size is strongly affected by forging conditions, many trial forgings are generally needed. On the other hand, grain size predictions by several simulations have been tried to reduce trial forgings. The purpose of this study is to predict grain size of Alloy 718 by combining a numerical simulation and a physical simulation. Firstly the transitions of temperature and strain of the forged material during hot forging were calculated by the 3-dimensional FEM. Secondly multi-stage plane strain compression tests using small test pieces were carried out by means of the Gleeble system according to the temperature and strain programs obtained by the numerical simulation, then the grain size was observed. These simulations were applied for predicting and refining the grain size of Alloy 718 billet forged by hydraulic 4-ram radial forging machine.