Modelling extrusion of 2618 aluminium alloy and 2618-10percent Al_2O_3 and 261 8-20percent Al_2O_3 composites

摘要

The metal matrix composites 2618-10percentAl_2O_3 and 2618-20percent Al_2O_3 have been subjected tohot torsion tests for temperatures T from 300 to 500 deg C andstrain rates #epsilon# radical from 0.1 to 5 s(-1) The flowstresses decrease with increasing temperature and decreasingstrain rate and the composites have greater strength than thematrix alloy. The strength of the extruded 2618-10percentAl_2O_3 is higher than that of the as cast 2618-20percentAl_2O_3. A constitutive analysis has been carried out with thesinh Arrhenius equation for the composites and the alloy. Plotsof log a versus log (sinh #alpha# #sigma#_p) and log(sinh#alpha# #sigma#_p) versus 1/T are approximately linear overthe range of conditions tested. To improve the deformationprocessing, which is required for many discontinuouslyreinforced metal matrix composites, the extrusion of the threematerials has been modelled using the finite element softwareDeform and the constitutive laws determined above. Ofparticular significance are the dependences of peak load andmaximum temperature on billet temperature and ram speed foran extrusion ratio of 31.