Some Characteristics of Hot-Extruded Powder Metal Billets

Abstract

Many alloys are difficult to manipulate by the hot-working of a cast ingot because the cast structure contains segregated areas of hard, brittle phases. The breakdown of such a cast structure into a uniform distribution of phases involves a lengthy and careful thermal working cycle. It is suggested this problem might be overcome and superior structures obtained by the consolidation of atomized prealloyed powders; such powders are necessarily free of macro-segregation. Hot extrusion of a compacted billet is confirmed as a valid technique. This paper describes experiments undertaken to assess the feasibility of the process. Initially, simple metals and alloys were investigated with a view to determining the extrusion parameters and the general quality of the extruded product. Later, more difficult materials were investigated. The properties of a number of materials extruded from powders are given. It is shown that a very fine and uniform distribution of phases can be obtained by this method, which in some cases gives superior properties.