Investigation on metallurgical and mechanical characteristics of gas tungsten arc welded al 6063 aluminium alloy using multi optimization techniques

Abstract

Aluminium is the third, most common, element found as 8 % by weight in the earth s crust. Considering materials engineering today, aluminium and its alloys are crucial for use in materials engineering. Its properties of excellent corrosion resistance, high strength and ease of fabrication combined with excellent combination of ductility and toughness renders it suitable for a wide range of industrial applications. It is most suited to a wide range of applications not only in aerospace industry but also in automobile industry, owing to its superior strength to weight ratio. Aluminium alloys of the AA 6xxx group have magnesium and silicon as the major alloying elements. The most common alloys in this group are 6061, 6063 and 6082. Aluminium alloy 6063 is a precipitation hardening alloy. It has a density of 2700Kg/m³ and the major constituents of the elements are 0.8% Mg, 0.7% Si, 0.34% Fe, 0.15% Cu and other elements like Cr, Mn and Ti in small quantities. This alloy exhibits good welding properties, while the presence of Magnesium and Silicon, in aluminium, form Magnesium Silicide (MgSi2) which provide A6063 with better strength via heat treatability. But, during fusion welding, the rate of heat generation (heat input) results in serious welding consequences such as solidification cracking, hot cracking, porosity, low strength in HAZ, vaporization of volatile elements, etc. Therefore, better selection of suitable welding process parameters a great care should be taken in order to achieve high quality welded joints. Among various welding processes, it was found that TIG welding was mostly used for joining of aluminium and its alloys. This was due to the reason that a pinpoint control of heat input generated by the TIG process resulting in narrow HAZ as compared to other arc welding processes. Therefore, for the present study of the effect of process parameters on mechanical, micro-structural and corrosion properties of welded joints, a tungsten inert gas welding process was used for butt jointing of a 6 mm thick A