Enegide, Fergus Uche,;Achebo J, and Osaremwinda, J.O, Nigeria
Controlling the temperature distribution in a weldment is critical; the thermal properties resulting from the temperature distribution have a great influence on the weld quality, especially during weld cooling and solidification process. Cooling time is a function of heat input, excessive heat input causes prolonged cooling time giving rooms to micro structural changes which can greatly affect HAZ, Mechanical properties etc. Therefore, minimizing the cooling time helps minimize the detrimental micro structural changes that may result from the process.
This study is aimed at optimizing and predicting cooling time of a welded structure. Response Surface Methodology (RSM) was the expert software used. Twenty sets of experiments were carried out, adopting the central composite experimental design. Tungsten inert gas welding equipment was used to produce the welded joints; Argon gas was supplied to the weld to shield it from atmospheric interference. Mild steel plates of 60x40x10mm were cut and used as specimen for the work. The k-type thermocouple was used to determine the ambient, solidus and liquidus temperatures
At the end of the research, the model produced a numerical optimal solution of: current 120.00 Amp, voltage of 23.79 volt and a gas flow rate of 15.71 L/min resulting in a welded material having a cooling time of 17.524 sec. This solution was selected by design expert as the optimal solution with a desirability value of 97.90%.