Analysis of Microstructural Changes in Enhancement of Surface Properties in Sheet Forming of Al alloys via Friction Stir Processing

Abstract

Weight reduction is one of the major objectives in engineering design and manufacturing, especially in automotive and aircraft industries. Aluminium (Al) alloys provide the solution for weight reduction in various structural applications. Forfurther enhancement ofsurface properties of these alloys, their surface composites are fabricated which exhibit high strength - weight ratio, better corrosion resistance, improved mechanical & wear properties as compared to base alloys. In this work, an attempt has been made to enhance the processed-layerhardness of AA 6063 sheets by synthesizing AA 6063/SiC surface composites using friction stir processing (FSP). Single pass FSP was performed on AA 6063 sheets using tool rotational speedat three levels of 900, 1120and 1400 rpm respectively.Traverse speed was maintained at a constant level of 40 millimetres/minute and tool tilt angle was kept at 2˚. Optical microscopy was employed for observing microstructureof fabricated composites. Uniform distribution of SiC particles in the metal matrix was achieved.The Combination of 1120 rpm, 40 mm/min and 2˚ gave most homogeneous distribution and highest microhardness of 87 Hv. No interfacial reaction was observed between the aluminium matrix and SiC particles.