Effect of particle morphology and size on roll compaction of Ti-based powders

Titanium and blended titanium alloy powders with varying particle morphologies and particle sizes were investigated for their rolling behaviours. The rolling behaviour was evaluated by measuring the density and thickness of strips produced by varying the roll gap size. The study was carried out to determine if the CSIR-Ti powder produced using the newly developed CSIR process could be successfully used in direct powder rolling and compare its rolling ability to that of potentially competing powders that are already commercially available. Three commercially available powders of different morphologies were investigated together with the new CSIR-Ti powder. Powder compressibility, flowability, particle morphology and particle size were determined. Direct powder rolling was carried out using a 55 mm roll diameter rolling mill by varying the roll gap size. Densities and thicknesses of the rolled strips were measured for every roll gap size used. Results indicate that the rolling behaviour varies with changes in morphology. Spongy and angular shaped powders were successfully rolled to dense strips with no visible defects. Spongy powders achieved higher densities than angular powders. The strip thicknesses decreased as the densities increased for all powders. Spherical powders produced strips that disintegrated as they emerged at the exit zone. Alloying Ti with Al-V master alloy powder significantly altered the rolling behaviour of the Ti powders. (C) 2014 Elsevier B.V. All rights reserved.