Some aspects on cold forging of aluminium–alumina powder metallurgy composite under triaxial stress state condition

Abstract

An experimental investigation on the cold forging of aluminium–3.5% alumina powder metallurgy composite under triaxial stress state condition has been studied in the present work. Sintered aluminium–alumina composite with three different height to diameter ratios, namely, 0.35, 0.56 and 0.72 with three different initial preform relative densities, namely, 0.72, 0.80 and 0.88 were prepared, sintered, furnace cooled and cold upset forged. A new expression for the determination of the radius of curvature of the barrel radius has been proposed based on the dimensional output and density measurement. This calculated barrel radius has been compared with the experimentally measured barrel radius. Various stress ratio parameters, namely, ( σ θ / σ z ), ( σ m/ σ z ), ( σ eff/ σ z ) and ( σ m/ σ eff) were determined using dimensional output and density measurement and their behaviour against the measured relative density and the measured barrel radius has been systematically analyzed. A straight-line relationship was observed for the measured and the calculated radius of curvature of barrel and an exponential relationship was found between the stress ratio parameters and the relative density.