The effect of impact compaction on surface quality of powder discs

Powder compaction by impact where high strain-rates occurs in the powder is attending an increasing interest. Impact compaction or high velocity compaction (HVC) is a production technique with capacity to significantly improve the mechanical properties of powder metallurgy (PM) parts. The HVC experiments were performed using a laboratory machine with a hydraulically driven hammer. This machine has maximum impact energy of 4 kJ. The powder materials used for the investigation were pre-alloyed water atomized iron based powders. Profile measurements of HVC and conventionally compacted (CC) 25 mm circular discs have been performed with a Wyko NT1100 using vertical scanning interferometry (VSI). For comparable densities the HVC discs have a significantly flatter and smoother upper surface (impact face) compared to CC discs