Investigation on the distribution and role of intermetallic aggregates in influencing the mechanical strength of the friction stir welded dissimilar mg al alloy joints

Abstract

In aerospace and automotive sectors, the reduction of weight of the components and parts are of major solicitude to enhance the fuel related economy and to curtail the emission of gases. Alloys of magnesium (Mg) possessing nearly 2/3rd the density of the alloys of aluminium (Al), was proven to be an effective and promising material for several industrial scenarios in boosting fuel savings, especially in the sectors of aerospace and automotive. For many decades, several alloys of Al have been employed extensively in a majority of industrial sectors owing to their modest volume of density, superior strength, appreciable intransigence against corrosion, easy degree of workability and formability, etc. At the same time, as one of the exceptionally lightweight metal, alloys of Mg inherits several unique features including an easy degree of recyclability, appreciable degree of hot formability, enhanced degree of castability, superior damping-related properties, etc. Joining together the alloys of Mg and Al during the fabrication of a single hybrid structural component will lead to the enhancement of several properties and will also contribute to a reasonable amount of weight savings of the fabricated component. To join together alloys of Al and Mg, several attempts were made using a wide variety of traditional and fusion- based welding processes including electron beam welding, laser welding, tungsten inert gas welding, induction welding, etc. However, welding of Mg-Al alloys employing these conventional joining processes is a quite complex task and attainment of joints is hindered due to obscure joint pool, larger solubility of hydrogen, higher level of oxidation, etc. In addition to this, the attained joints were found to possess severe flaws including cracks induced by liquation and porosity generated due to the entrapment of hydrogen in the interior portion of the joint in the interim of solidification newline