This present paper is an experimental study aiming to optimize the welding process parameters and ageing parameters to improvise the outcome of ultimate tensile strength and hardness on welded joint interface of dissimilar materials. In order to evaluate these parameters suitable heat treatment parameters like solutionizing and Artificial ageing methods are considered with different elevated temperature - time conditioning with suitable welding parameters like current, voltage, welding speed, Inert gas, to observe the change in behavior before and after heat treatments of welded joints and to find the optimized and best suited variables to manufacture a sound welded joint an statistical approach like Taguchi methodology is employed. It is found that by means of an appropriate selection of age hardening parameters, it is possible to achieve a better understanding of joining of TIG welded AA 6061 and AA 5154 aluminium alloy.