Squeeze casting of aluminium alloys for higher formability in cold forging

Abstract

This research project investigated the process conditions of using squeeze casting process to produce aluminium alloy preforms or billets for subsequent cold forging process. The comparative effects of heat treatments, their microstructures and mechanical properties were evaluated. Through these studies and experiments, the main emphasis is on the study of commercial material Al 6061, Al 2014 and Al 356 alloys. The formability of the alloys was carried out using forward and backward extrusion test at 50% area reduction at room temperature (cold extrusion). It was found that when wrought aluminium 6061, 2014 and 356 alloys were squeeze cast to form the preforms, the preform microstructures revealed very fine microstructures that are feasible to be cold extruded. In addition, after thermal annealing treatment of 6061 squeeze cast preforms, the samples showed a similar value of work hardening exponent value of 0˙20 as compared to the wrought aluminium alloy 6061, with a workhardening exponent value of 0˙21 obtained from the static compression test. Wrought aluminium alloys generally cost twice the amount as compared with casting ingots. The microstructures of the squeeze cast 6061 alloy showed no visible cracks or inclusions after the deformation by extrusion. The results of the studies showed that Al 6061 preforms via squeeze cast technique may be cold extruded or formed, which provide an alternative means for the production of billets for the cold extrusion or forging process.