Abstract：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.
2017, 
