The dies were examined optically and the dimensions of
the profile accurately measured. Then they were tested with
penetrate liquids in order to reveal eventual fine cracks
abutting on the surface. The hardness of the used dies
was measured using a Vickers tester. After this preliminary
examination, the dies were cut along their length in order
to examine the internal area of the profile. Metallographic
samples were cut out for studying the microstructure withan optical and electron (SEM) microscope equipped with
an EDS microanalysis system. The microhardness of the
material was measured with a Vickers microhardness tester
and the macrohardness with a Rockwell tester. Unused
material was also examined in the same manner in order
to assess the microstructural changes occurring during
extrusion.