ANALYSIS OF HARDNESS VARIAIONS IN ALUMINIUM ALLOYS AFTER FRICTION STIR WELDING/FRICTION STIR PROCESSING

Abstract

Joining and processing of some aluminium alloys is a difficult work due to oxide layer on the surface. With introduction of friction stir welding (FSW) technology it has become quite feasible for joining difficult-to-weld Al-alloys. It has been implemented by many industries for manufacturing of several products. Friction stir processing (FSP) is relatively a new process used for microstructural modification. It is derived from FSW. It is an effective technique for grain refinement. The refinement enhances mechanical properties and fulfils the application requirements. Aluminium alloys are categorized into two types that are heat treatable or precipitate hardened alloys and non-heat treatable or non-precipitate hardened alloys. The first category consists of alloy from 2000, 6000, 7000 and 8000 series. The later contains alloy from 1000, 3000 and 5000 series. In this report significance of friction stir welding/friction stir processing in aluminium alloys is addressed. Emphasise has been given to find out the dependence of hardness on various parameters and heat treatment conditions after FSW/FSP in various series of aluminium alloys. The parameters observed are welding parameters like rotational speed, traverse speed, tilt angle, velocity Index. Apart from this the similarities in hardness after FSP/FSW among the two categories of aluminium alloys is explained.