Effect of multiple impacts on high velocity pressed iron powder

High velocity compaction (HVC) process is a promising method for preparing high density powder metallurgy (PM) components with cost-effective. In the paper water atomized pure iron powder with 0.5 wt.% zinc stearate added was compacted by HYP35-7 High Velocity Compaction Machine. A computer controlled universal testing machine was used to measure the bending strength of samples. The effect of multiple impacts on the green density, the bending strength and the stress wave was discussed. The results show that at the identical total impact energy the green density and the bending strength of compacts pressed by double impact are the highest, whilst that of compacts prepared by triple impact is the lowest. In addition, the response time of stress wave is shortened gradually with increasing compacting numbers. Furthermore, the duration of stress wave of the second impact of double impact is the longest, but no obvious difference between that of single impact and the third impact of triple impact can be brought out. The comprehensive effect of the pressure and the duration results in the green density and the green strength increasing.