May 13 - 16, 2008
Gaylord Palms
Orlando, Florida USA

Extrusion/Die Theoretical

060 TH 
Wednesday, May 14 - 10:30am

Influence of Geometric Dynamic Recrystallization in the Dead Metal Zone on Peripheral Coarse Grain Defect Formation in Indirect Extrusion

Alexander Bandar -- Scientific Forming Technologies Corporation USA;
William Van Geertruyden -- EMV Technologies LLC, USA;
Wojciech Misiolek -- Institute for Metal Forming, Lehigh University, USA

Metallurgical analysis of partially indirectly extruded 6061-alloy billets reveals fine, equiaxed, high-angle boundary grains in the dead-metal zone (DMZ) developing into peripheral coarse grain defect. Finite Element Modeling (FEM) indicates significant deformation in the DMZ. A mesoscale model is presented, particularly 3-D grain geometry, low-to-high-angle boundary ratios, and grain shape change effects during deformation. Experiments, FEM simulations, and EBSD analyses are reviewed.