WORKABILITY IN FORGING OF POWDER-METALLURGY COMPACTS

The power metallurgy (PM) technique is now applied widely to many indu stries and materials. To obtain more reliable PM products, many second ary processes are applied to PM preforms. The problem of deformation a nd fracture of PM preforms still needs a considerable amount of invest igation. In this work, the effect of the relative density on the formi ng limit of PM compacts in upsetting is investigated. A workability fa ctor describing the effect of the mean stress and the effective stress - which latter is a function of the relative compact density - is pre sented. The effect of the relative density is discussed using two theo ries for PM characterization in deformation and fracture.