CHARACTERIZATION OF COLD FORGED SPRAY FORMED Al-Si ALLOYS

Abstract

The microstructural characteristics, porosity, hardness and wear behaviour have been investigated for cold forged spray formed Al-6Si alloy. The Comparison of these characteristics has been done among the without forged sample and uniaxially cold forged samples with 25%, 50% and 75% thickness reduction. The microstructure of spray formed Al-6Si alloy showed the equiaxed grain morphology for the a-Al phase and uniformly dispersed eutectic Si phase at the inter particle boundaries. Uniaxial cold forging decreased the porosity level thereby increasing the hardness and refining the microstructure with elongation of grains normal to the direction of forging. Dry sliding wear tests were performed on pin on disc machine with 1-5 kg loads for without forged and forged samples. The samples with 75% thickness reduction showed good wear resistance than that of without forged, 25% and 50% thickness reduced samples. The wear behaviour is discussed in the light of micrcostructural evolution during cold forging. The worn surfaces were characterized by SEM-EDS and the debris collected during wear test was characterized by XRD.