Pressed and sintered AISI 4140 PM low alloy steel from gas atomised powders

Abstract

In conventional PM of low alloy steels various alloying routes are used (fully prealloyed powders, diffusion alloying, elemental powders), but always using powders that allow uniaxial pressing, i.e. acceptable compressibility and flow. Fully prealloyed gas atomised powders (including carbon content) have never been an option because their small size. These powders need to be granulated before being uniaxially pressed and the binder used in the granulating process must be eliminated in the first steps of the sintering cycle. Such a processing route is proposed and initial results presented. A potential advantage of the process is that a low particle size can activate the sintering performance, bringing energy and cost savings over the full process cycle.