Rotary Forging of Sintered Iron Based Composites

Abstract

Sintered iron based composites, consisting of a matrix of high speed steel, stainless steel, unalloyed iron powders, and dispersed Si₃N₄ particles, are being developed to meet the needs of arduous wear conditions at both ambient and elevated temperatures. Use as valve seats in heavy duty diesel engines is envisaged. A route for producing such composites, including mixing of powders, pressing, presintering, and rotary forging, is described. It is shown that up to 3 wt-% (7 vol.-%) of Si₃N₄ particles can be incorporated successfully in alloyed iron based matrixes, and that relative densities up to 95·8% can be reached by rotary forging from sintered preforms of initial density 78–80%. The effects of different additives, processes, and rotary forging parameters on final rotary forged densities were studied to optimise the production routes for different compositions. PM/0544