Consolidation of Nitrogen Gas Atomized Aluminum Powder by Sheath Rolling

Abstract

Nitrogen gas atomized aluminum powder was consolidated by a powder-in sheath rolling method. Aluminum powder was filled in aluminum tube of 12 mm in outer diameter and 10 mm in inner diameter. The sealed tube containing powder was rolled to the thickness of 6 mm at ambient temperature for compaction and then consolidated by the combination of cold rolling and subsequent hot rolling at various temperatures ranging from 360 to 560°C. Rolling schedule is determined as to obtain flat bar with the thickness of 3 mm. The relative density of consolidated powder compact was more than 0.96. The mechanical property of powder compact was affected by rolling schedule and temperature. The strength of powder compact was comparable to that of bulk material. When cold reduction or hot reduction was large, the elongation of powder compact became large. However, elongation decreased with the combination of moderate cold and hot rolling. The interparticle bonding necessary for consolidation was accomplished during heating after cold rolling when large cold reduction is adopted. On the other hand, bonding is accomplished during and/or after hot rolling in large hot reduction. This method is promising for fabricating composite materials on the powder metallurgy route.