Optimal die profile design for uniform microstructure in hot extruded product

The objective of this study is to design the optimal die profile that can y ield more uniform microstructure of a hot extruded product. The microstruct ure evolution, such as dynamic and static recrystallization, and grain grow th, is investigated by using the program combined with Yada and Senuma's em pirical equations and rigid-thermoviscoplastic FEM. The die profile of hot extrusion is represented by a Bezier-curve to generate all the possible die profiles for a given extrusion ratio and initial radius of the billet, In order to obtain the optimal die profile which contributes to uniform micros tructure of the product, the FPS (Flexible Polyhedron Search) method is app lied to this study. To show the validity and effectiveness of the result of this study, an experiment of hot extrusion is performed, and the result of simulation is in good agreement with that of the experiment. (C) 2000 Publ ished by Elsevier Science Ltd. All rights reserved.