Abstract
Direct powder rolling (DPR) is an unconventional powder metallurgy
technique for fabricating flat mill products. It offers significant cost reduction by using
low processing temperatures and reduced fabrication steps compared to ingot
metallurgy. Roll compaction is the first stage in the DPR process, hence proper selection
of roll compaction parameters is vital for achieving high density defect free (no visible
cracks, alligatoring or centre split) green compacts. Unsuitable roll compaction
parameters can result in fragile low green density strips which could be difficult to
handle during subsequent processing or high green density strips with defects. The focus
of this study was therefore, to determine the range of roll compaction parameters
required in producing high density, defect free strips. The Ti-6Al-4V strips studied were
produced by mixing 150 μm titanium hydride de-hydride powder with a 45 μm 60Al40V
master alloy. The powder mix was roll compacted at varying roll gaps and rolling
speeds. The compacted strips were evaluated by measuring the green strip density and
thickness. It was concluded that for the Ti-6Al-4V powder studied in this work, the
preferred roll compaction parameters for achieving high density, defect-free green strips
are 0.3 mm to 0.5 mm roll gap with roll speeds from 3 rpm to 10 rpm.