Using a mesh-reconstruction technology of welding-plane

the porthole die extrusion process of an hollow profile was successfully simulated based on software DEFORM-3D. The metal flow behaviors

velocity distribution regularities were revealed. Combining with the effective stress and strain on the profile

the distribution of grain size on the profile and its causes were discussed. The result shows the stress and strain distribution of the extrusion profile has certain corresponding relation with the grain size distribution

in other words

finer grain size at the corner area and inner part of the hollow profile result from the concentration of the stress and strain during the extruding.