CHARACTERIZATION OF WARM ROLLED Al-Si GRAPHITE SPRAY FORMED COMPOSITES

Abstract

Spray Forming (SF) is an advanced materials processing technology and relatively new metallurgical process that deposits atomized droplets of molten metal onto a substrate into a near net shape. Aluminum (Al)-Silicon (Si) alloy with addition of graphite provides for high strength to weight ratio, low cost and enhanced material properties and performance. Processing of these alloys is difficult by means of conventional casting process since coarse primary silicon phase precipitates in the material and causes reduction of mechanical properties and workability. In the present investigation, Al-Si-Gr composite is produced by spray forming and then warm rolling was done to refine the microstructure of spray formed Al-Si-Gr composite. The aim of the current research work is to study Al-Si-Gr composite and examine the changes produced in microstructure and mechanical properties of the material after warm rolling. In this study spray forming technique was used to synthesize Al-Si-Gr composites for cylinder liner application. Silicon (Si) and graphite (Gr) particles are uniformly distributed in Al-matrix, which do not get distributed uniformly by conventional casting processes. Disc shape spray form casting was made of Al-20Si-4Gr composite and then its microstructures were studied. In addition to that, spray formed Al-Si-Gr composites were subjected to warm rolling. It was introduced to eliminate the porosity present in the spray formed composite. Warm Rolling resulted in complete homogenization and elimination of casting defects especially porosity. Mechanical properties like hardness, tensile strength and wear resistance were sharply improved after Warm Rolling