Machinability of Short Potassium Titanate Fiber Reinforced AC4A Aluminum Alloy Composite

Aluminum alloy composites reinforced with short potassium titanate fibers were fabricated by squeeze casting, and the effect of the fiber reinforcement on the machinability of the alloy under various cutting conditions were investigated. The fibers were randomly arranged in the alloy matrix, and no agglomeration of the fibers or porosity was observed. Although the cutting force of the AC4A alloy decreased as the cutting speed increased, that of the composites little changed even though the cutting speed increased. When the cutting speed was 50 m/min, the cutting force of the AC4A alloy significantly decreased due to the fiber reinforcement. When the cutting speed was 100 and 150 m/min, the cutting force of the composites was equivalent to or less than that of the AC4A alloy. The variation in the fiber volume fraction only slightly affected the cutting force values of the composites. The roughness of the machined surface of the AC4A alloy increased as the feed rate increased, and decreased as the cutting speed increased. The fiber reinforcement diminished the variation in the roughness due to the feed rate and Cutting speed. When the feed rate was high, the roughness of the composite having a high fiber volume fraction was almost equivalent to the theoretical roughness. This indicates that the fiber reinforcement suppresses the formation of the built-up edge. The machined surface and chip forms indicated that the fibers in the composite facilitated the shear deformation of the chips because the fibers were easily sheared by the cutting. These results lead to the conclusion that the machinability of the composite is superior to that of the AC4A alloy. [doi: 10.2320/matertrans.MER2008180]