EFFECT OF INTITIAL GRAIN SIZE ON EQUAL CHANNEL ANGULAR PRESSING

During last decade, Equal Channel Angular Pressing [ECAP] has emerged as a widely known procedure for the fabrication of ultra fine-grained metals and alloys. ECAP imposes large plastic strains on billets via a pure shear strain state. Intense plastic strain is introduced into materials without changing the cross sectional area of deformed billets in this technique. The interaction of shear plane with texture and crystal structure plays a primary role in grain refinement. The present work involves in study of initial microstructure on ECAP. Three different samples were prepared through sand casting, chilled casting and normal casting (using metallic mould). These samples were subjected to repeated pressings with a rotation of 1800 in each pass. Representative samples are taken after every two passes from the deformed samples to examine the grain size & shape effects on deformation and the corresponding hardness values are also reported for successive samples.