純鉄粉末のシース・温間孔型ロール法による固化成形

抄録

Metal powders produced by mechanical milling show the specific microstructures and properties. With these merits preserved, the powders should be combined into a large size compact. Saito et al. and Kimura et al. have succeeded in consolidating the iron powders into 12.5 mm thick sheets by sheath rolling at a relatively low temperature of 973K. Based upon their success, we have attempted to apply caliber rolling for consolidating the powders into a large bar (φ11 × 1 000 mm). The sheath can was filled with pure iron powders, sealed in vacuum, and then rolled. When the rolling temperature was 973K, rolling reduction of more than 80 % was enough to make sound compacts of >10 mm diameter with fine microstructure and relative density larger than 99.6 %. When the rolling reduction was 90 %, the consolidation was accomplished in a wide range of rolling temperature between 1 273K and 823K. At 823K and 873K, the sound consolidation could be realized without recrystallization. The tensile properties were better than those of the HIP treated compact. Hence, the solid-state joining is confirmed to occur much easier in the present method than in the HIP method.