Finite element analysis using dynamic material model to design process variables of radial forging

In order to obtain a refined and uniform microstructure in the final billet, the radial forging process needs to be optimized and controlled with various process parameters such as temperature of ingot and die, die size, ram speed, upset ratio, etc. Grain size control is one of the most effective ways for the control of mechanical properties. The change in grain size is significantly related with strain, strain rate and temperature of forged part. To understand material properties and to analyze stability and instability area of forged workpiece, hot compression test of Ti-6Al-4V was carried out within the strain-rate range 10(-2) to 10 s(-1), and the temperature range 800 to 1100 degrees C. And dynamic material map of Ti-6Al-4V was tabulated. In this study, a three-dimensional rigid-plastic finite element method(FEM) was used to analyze the radial forging process, focusing on the effects of feed rate and rotation angle for appropriate forging pass schedule. And the simulation result was confirmed with dynamic material model of Ti-6Al-4V. The optimal combination of feed rate and rotation angle has been determined by quantifying the radius profile in the longitudinal direction, roundness of the product and uniform strain distribution.